DE102014204097A1 - Methods, systems and apparatus for reducing steering wheel vibration in electric power steering systems - Google Patents

Abstract

Methods and systems are provided for suppressing steering wheel vibrations generated by periodic disturbances in a vehicle steering system. An exemplary method of reducing steering wheel vibrations caused by periodic disturbances comprises determining a gross torque attributable to the periodic disturbances in the steering system, determining a desired amount of suppression of the vibrations at the steering wheel, determining an offset torque based on the gross torque and the desired amount of suppression and generating of a motor control command signal in a manner influenced by the offset torque. The motor control command signal is provided to an electric motor coupled to the steering wheel and / or the vehicle tires, and the motor control command signal affects the torque applied by the motor to assist in steering the vehicle tires by the steering wheel in a manner that reflects the vibrations communicated to the steering wheel attenuates to the desired extent.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

TECHNICAL AREA

Embodiments of the present invention generally relate to electric power steering (EPS) systems and, more particularly, to techniques for reducing periodic steering wheel vibrations (SWVs) that occur in an EPS system.

BACKGROUND

Power Steering Systems (EPS) use an electric motor that can be coupled directly to either the steering box or the steering column to reduce the driver's effort in steering the vehicle. To explain in more detail: during operation of the vehicle, the driver will exert a force on the steering column (SW) in an effort to steer the vehicle. This results in a driver-induced torque applied to a shaft coupled to the SW. Torque sensors detect torque applied by the driver to the steering column and communicate this information to an electronic control unit. The electronic control unit generates a motor control signal that is supplied to the electric motor, causing it to generate an "engine assist torque" that is combined with the driver torque. This combined torque is then used to steer the "corners" of the vehicle. This allows varying the amount of support depending on driving conditions.

There are numerous types of unwanted vibrations, noises, pulsations, disturbances, and other forms of fluctuating vibration energy that can occur in a vehicle; these phenomena are collectively referred to hereafter and generally as "vibrations". Vibrations can have multiple sources, including external sources such as irregular road surfaces as well as internal sources.

When a vehicle is traveling at typical highway speeds (eg, 45-90 mph), the excitation of deviations at the corners of a vehicle may result in internally generated periodic torsional vibrations in the vehicle steering wheel. As used herein, the term "corner" refers to parts at the road-wheel positions of a vehicle from the tie rod to the outside. The parts that belong to a corner include a tire, wheel, disc brake, wishbone, steering knuckle, steering knuckle, bushings, etc. One example of an internal source of vibration is a non-centric, unbalanced, or otherwise unevenly rotating part. For example, when a tire, a wheel, a wheel hub, and / or a rotor is made in a non-concentric or unbalanced manner or mounted to the vehicle, the part will rotate with an unbalanced weight distribution. This can subsequently produce periodic or harmonic vibrations in the vehicle; d. that is, first order component vibrations around a first order frequency, as well as higher order or multiple order components around frequencies that are integer multiples of the first order frequency. A first order component of a periodic vibration is centered at the same frequency as the rotating object from which it originates and, in steering systems, usually has a greater amplitude or intensity than its higher order counterparts. For example, a wheel that rotates at fifteen revolutions per second (15 Hz) can produce periodic vibrations having a first order component at 15 Hz, a second order component at 30 Hz, a third order component at 45 Hz, and so on , The first order or 15 Hz component is usually more intense than the second and third order components. It should be understood that non-concentric rotating parts are only one possible source of periodic vibration in a vehicle, as there are many others.

Periodic vibrations caused by internal sources can propagate through the vehicle and can cause unwanted shaking or unwanted movement of certain vehicle components, which is noticeable to the driver. For example, periodic vibrations generated at the wheel sections or corners may mix and create a dynamic torque on a steering column component that causes the steering wheel to rotate cyclically with small amplitudes in both directions. When this type of operation occurs on a smooth or fine road surface, it is all the more apparent to the driver and is sometimes referred to as "fine road shaking" (SRS) or torque vibration. These vibrations can be felt by the driver of the vehicle and will hereafter be referred to as steering wheel vibrations (SWVs). The frequencies of SWVs are normally proportional to the speed and a first order harmonic of the tire's rotational frequency (eg, the rolling frequency of the tire). Dynamic amplitudes are small, close to the detection thresholds of 0.03 degrees or above.

A variety of techniques have been developed for reducing or mitigating periodic vibrations in the vehicle. These techniques include wheel balancing on the vehicle and separately using various types of Damping parts and attempts to produce by machining or other manufacturing more concentric and precise parts. In vehicles employing electronic power steering systems (EPSs), EPS control algorithms have been developed that allow SWV active suppression techniques to be implemented, but these methods may be more expensive and may or may not require new hardware and / or wiring effective for suppressing. These algorithms may also interfere with ordinary driving (ie, affect the perception of the steering performance as perceived by the driver) and / or make the system less stable (in a buoyant sense) by producing larger aperiodic SWVs on bumpy roads or by achieving vibrations caused by them limit cycle conditions.

Accordingly, it would be desirable to provide improved methods, systems, and devices for suppressing SWVs in an EPS system. It would be desirable if such methods, systems and devices do not require additional hardware or wiring such that they can be commonly used in many types of vehicles without requiring significant changes. Furthermore, other desirable features and features of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

SHORT VERSION

Embodiments of the present invention relate to methods, systems and apparatus for suppressing steering wheel vibrations (SWVs) occurring on the steering wheel of a vehicle having an electric power steering (EPS) system.

In one embodiment, an electric power steering system (EPS) is provided that may be implemented in a vehicle to reduce steering wheel vibrations (SWVs) notified to the vehicle steering wheel. The EPS system includes an electric motor configured to generate engine torque in response to a motor control signal, and a sensor that detects torque and generates a periodic electrical torque signal that includes torque sensed between the steering wheel and the transmission of the electric motor embodies.

In some embodiments, it may be desirable to control or otherwise adjust the extent (or degree) at which steering wheel vibrations attributable to periodic disturbances within a steering system are suppressed / damped. Accordingly, there is provided an exemplary method for reducing steering wheel vibration caused by periodic disturbances, which includes determining an estimated total torque attributable to the periodic disturbances in the steering system, setting a desired amount of damping of the vibrations, and setting an offset torque based on the total steering wheel torque and desired amount of damping. The offset torque is used to generate adjusted lateral and longitudinal torque components that are supplied to the respective extraction modules to generate extraction signals based thereon such that the generated gain and phase compensated motor drive control signal is affected by the offset torque. In this way, the offset torque affects the motor torque supplied by the electric motor used as a steering assist to dampen the vibrations imparted to the steering wheel to the desired extent.

In accordance with one or more embodiments, a vehicle includes a steering wheel coupled to one or more vehicle tires to facilitate steering of the one or more tires, an electric motor coupled to the one or more vehicle tires, and / or the steering wheel to generate an engine torque that assists in steering the one or more tires and a control module coupled to the electric motor. The control module determines a total torque attributable to the periodic disturbances in the vehicle, sets a desired amount of damping for the periodic disturbances in the steering wheel, determines an offset torque based on the total torque and the desired amount of damping, and generates a motor drive control signal in a manner by the offset torque is affected, wherein the motor drive control signal is applied to the electric motor to control the motor torque and to dampen the periodic disturbances communicated to the steering wheel to the desired extent.

In another embodiment, a method is provided for reducing steering wheel vibrations caused by periodic disturbances in a steering system corresponding to one or more vehicle tires, the steering system including the steering wheel to permit steering of the one or more tires, and an electric motor coupled to the steering wheel and / or the one or more tires to produce an engine torque that aids in steering the one or more tires. The Method comprises determining lateral and longitudinal components of a measured disturbance torque at an angular frequency corresponding to the one or more tires, determining a motor torque, and determining a total torque attributable to the periodic disturbances in the steering system based on the cancellation component and the lateral and Longitudinal components of the measured disturbance torque at the angular frequency. The method continues with setting a gain corresponding to a desired amount of damping of the vibrations and multiplying the total torque by the gain to obtain an offset torque. The method proceeds by transforming the offset torque into lateral and longitudinal offset torque components, generating a cross-extracted component corresponding to an amplitude envelope of a first difference between the transverse component of the measured disturbance torque at the angular frequency and the lateral offset torque component, and generating an extracted longitudinal component corresponding to an amplitude envelope of one second difference between the longitudinal component of the measured disturbance torque at the angular frequency and the longitudinal offset torque component. The motor drive control signal is generated based at least in part on the extracted lateral and longitudinal components, and the motor drive control signal affects the motor speed to dampen the vibrations imparted to the steering wheel to the desired extent.

DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be described below in conjunction with the following drawing figures, wherein like reference numerals denote like elements, and

1 shows a perspective view of an exemplary rack and pinion steering assist system (EPS) used in a vehicle;

2 Figure 10 is a block diagram of a steering system including a control loop for an EPS system of a vehicle according to some of the disclosed embodiments;

3 FIG. 10 is a block diagram illustrating an implementation of the SWV suppression control module of FIG 2 according to some of the disclosed embodiments;

4 FIG. 10 is a flowchart showing a method of reducing SWVs in a steering wheel according to some of the disclosed embodiments; FIG.

5 FIG. 10 is a block diagram showing one embodiment of a control module suitable for use as the suppression control module of FIG 2 according to one or more embodiments; and

6 FIG. 10 is a flowchart showing a procedure for dynamically reducing SWVs in a steering wheel to a desired extent according to one or more embodiments.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit its application and use. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

Before describing embodiments in detail that are in accordance with the present invention, it should be noted that the embodiments relate to methods, systems, and devices for suppressing or reducing steering wheel vibrations (SWVs) in a vehicle using an Electric Power Steering Assistance (EPS) system. The methods, systems, and devices described herein may be used to reduce the effects of periodic vibration in an electric power steering (EPS) system, particularly those that may result in fine road jarring (SRS), torque jitter, and / or other undesirable conditions. In accordance with an exemplary embodiment, a controller is provided that may generate appropriate engine control signals that, when applied to an EPS electric motor, will counteract vibrations in the EPS system to cancel out the periodic vibrations produced by one or more wheels or corners.

For discussion purposes, the EPS system may be artificially divided into a first portion located above the sensor and a second portion located below the sensor. Generally speaking, the first portion includes the vehicle steering wheel and the second portion includes the electric motor. As will be appreciated by those skilled in the art, in a rack and pinion EPS system, the sensor is disposed on a drive shaft of a steering gear and the first portion located above the sensor includes elements such as the steering wheel, steering column, intermediate steering shaft, subsequent clutches, etc., while below the sensor arranged elements such as the electric motor, a rack, a Rack housing, tie rods, corner damper, etc. contains. In contrast, in a steering column EPS system, the sensor is integrated in the steering column and disposed between the steering wheel and the teeth of the electric motor with the steering shaft. The first portion located above the sensor includes elements such as the steering wheel, while the second portion located below the sensor includes such elements as the electric motor, intermediate steering shaft, subsequent clutches, tie rods, corner dampers, and the like.

The vehicle contains an on-board local area network (LAN). The LAN communicates angular position information concerning the change in the angular position of a wheel (or wheels) over a time interval. For example, in one implementation, the angular position information may be burst information of the antilock braking system (ABS) that is regularly communicated through the onboard LAN. This ABS burst information is in the form of a number (N) of pulses over a time interval and may be used to determine that a tire has rotated through a certain angular movement within a time interval.

According to some of the disclosed embodiments, the EPS system includes an electronic control unit (ECU). A first module implemented in the ECU includes an estimation module that generates an estimated instantaneous angular velocity signal based on the angular position. The estimated instantaneous angular velocity signal corresponds to a particular angular frequency of the tire at the current time. The first module also includes an integrator module configured to generate an estimated angular position signal (corresponding to the tire) based on the estimated instantaneous angular velocity signal.

In accordance with the disclosed embodiments, the ECU generates a gain and phase compensated motor drive control signal at the determined angular frequency. The gain and phase compensated motor drive control signal is fed back to adjust the current of the electric motor and control the motor torque such that the selected periodic content of an electronic signal detected angular difference between a first angular displacement (θ _{above_sensor} ) of the first portion (above the sensor). and a second angular displacement (θ _{below_sensor} ) of the second portion (below the sensor) is reduced. The ECU uses the estimated angular velocity and the estimated angular position of the tire (along with other amplitude and phase adjustments described below) to ensure that the ECU is operating at the correct frequency to ensure that the periodically varying angular difference is reduced. In this way, the gain and phase compensated motor drive control signal causes the electric motor to adjust the motor torque to dynamically decrease periodic portion of the periodic electrical torque signal (at the determined angular frequency corresponding to a sensor sensed jamming signal) while dampening vibrations transmitted to the steering wheel.

In accordance with some of the disclosed embodiments, a second module implemented in the ECU includes a sinusoidal generator module, an overlay module, and an extraction module.

The sine curve generator module generates sinusoidal signals at the periodic frequency corresponding to the estimated angular velocity (eg, the estimated tire frequency) based on the estimated angular position signal. The sine carrier signals include: a sine function carrier signal at a periodic frequency corresponding to an expected periodic noise signal at the sensor and a cosine function carrier signal at the periodic frequency corresponding to the expected periodic noise signal at the sensor and 90 degrees out of phase with respect to the sine carrier signal. It will be noted that the periodic electrical torque signal has a frequency at the frequency of sine carrier signals, but the amplitude of the periodic electrical torque signal content and the phase shift between the periodic electrical torque signal and the sine carrier signals are unknown.

The overlay module mixes the sine carrier signals with the periodic electrical torque signal to produce a mixed sine signal corresponding to an extracted cross component of the amplitude of the periodic interference signal detected at the sensor module and a mixed cosine signal corresponding to an extracted longitudinal component of the amplitude of the periodic interference signal detected at the sensor module ,

Each of the extraction modules operates a proportional integral-derivative submodule (PID submodule) which processes the mixed sine signal and, correspondingly, the mixed cosine signal. Each PID submodule can apply proportional (P) gain, integral (I) gain, and derivative (D) gain to the mixed sine or cosine signal. The P, I, D gains can be set according to adjustment input parameters that depend on the particular system. The extraction modules may thus perform a proportionality scaling function, an integration scaling function and / or a differentiation scaling function (collectively referred to in the art as "Proportional Integral Derivative (PID) scaling functions) and, optionally, separate low pass filtering stages at the output of each gain block. The output of this extraction module is a weighted combined signal with scaled proportional, integral and derivative components. In other words, the first extraction module processes the mixed sine signal and the second extraction module processes the mixed cosine signal to generate signals including a first extraction signal including a weighted combined first mixed sine signal and a second extraction signal including a weighted combined first signal contains mixed cosine signal.

The optional low pass filtering that may be implemented may be used to extract a low frequency portion from the internal PID signals to produce filtered signals that may be added together to produce the combined extraction signals. In some embodiments, each of the extraction modules may also receive adaptation input parameters used to alter the characteristics of the extraction modules (eg, reducing response time to relatively fast transients based on velocity changes during longitudinal acceleration or vehicle deceleration and / or increasing response time during steering operations). Forced continuity in individual state changes (eg, from uncontrolled to controlled, or from not accelerating to accelerating, and vice versa) can be enforced as a state change of the integrator function and can be easily implemented using methods known to those skilled in the art.

For example, in one embodiment, the first extraction module includes a first proportional-integral-derivative (PID) sub-module, first filters, and a first adder. The first proportional-integral-derivative (PID) submodule receives adjustable input parameters and scales the mixed sine signal by applying respective gains from proportional, integral, and derivative gain blocks to produce a proportional scaled sine signal, an integral scaled sine signal, and a derivative scaled sine signal. In one embodiment, the respective gains may be varied based on fit input parameters. A first filter is provided for each of the signals, proportionally scaled sinusoidal, integral scaled sine, and derivative scaled sinewave. The first filters are configured to extract low frequency content from the proportional scaled sine signal, the integral scaled sine signal, and the derivative scaled sine signal to produce a filtered proportional scaled sine signal, a filtered integral scaled sine signal, and a filtered derivative scaled sine signal. The first adder sums the filtered proportional scaled sine signal, the filtered integral scaled sine signal, and the filtered derivative scaled sine signal to produce a first extracted signal that is a weighted combined version of the filtered proportional scaled sine signal, the filtered integral scaled sine signal, and the filtered derivative scaled sine signal.

The second extraction module includes similar adders, amplifier blocks, and filters and uses these components to generate a second extracted signal that is a weighted-combined version of the filtered proportional scaled cosine signal, the filtered integral scaled cosine signal, and the filtered derivative scaled cosine signal.

The multiplexer module then multiplexes the extracted sine signal and the extracted cosine signal to produce multiplexed extracted signals.

Before applying the EPS system, a transfer function is estimated that characterizes the dynamic relationship between the motor drive command to the electric motor and the periodic electrical torque signal output of the sensor. This estimated transfer function can be used to generate an inverse transfer function that is a discretized representation of the inverse of the estimated line transfer transfer function. This inverse transfer function can be used to generate a lookup table that generates a variety of entries. Each entry contains: (1) either a frequency or a value of instantaneous speed; (2) a carrier phase angle adjustment value corresponding to the frequency or value of the instantaneous angular velocity and the desired line balance, and (3) a gain adjustment value corresponding to the frequency or value of the instantaneous angular velocity. The carrier phase angle adjustment value is the sum of the angle of an inverse transfer function and the line balance at the frequency or value of the current angular velocity, and the gain adjustment value is the magnitude of the inverse transfer function at the frequency or value of the instantaneous angular velocity.

According to some of the disclosed embodiments, a third module implemented in the ECU includes Carrier phase angle adjustment and modulation module, a switch module and an amplifier module.

In one embodiment, the carrier phase angle adjustment and modulation module includes a first mixer module and a second mixer module. The first mixer module generates a phase matched sine function carrier signal by modifying the sine function carrier signal based on the carrier phase angle adjustment value and the line trim information at the value of the estimated instantaneous angular velocity. The first mixer module then amplitude modulates the phase-matched sine function carrier signal based on the extracted sine signal and the extracted cosine signal to produce a phase-matched, amplitude modulated sine carrier signal. For example, in one implementation, the first mixer module generates the phase-matched amplitude-modulated sine function carrier signal by calculating cos (u [4]) * u [2] - sin (u [4]) * u [3]) * u [1] u [1] is the sine function carrier signal, u [2] is the extracted sine signal, u [3] is the extracted cosine signal, and u [4] is the carrier phase angle adjustment value adjustment signal.

The second mixer module generates a phase matched cosine function carrier signal by modifying the cosine carrier signal based on the carrier phase angle adjustment value and the line trim information at the value of the estimated instantaneous angular velocity. The second mixer module then amplitude-modulates the phase-matched cosine function carrier signal based on the extracted sine signal and the extracted cosine signal to form a phase-matched, amplitude-modulated cosine carrier signal by calculating cos (u [4]) * u [3] + sin (u [4]) [2]) · u [5] where u [2] is the extracted sine signal, u [3] is the extracted cosine signal, u [4] is the carrier phase angle adjustment value adjustment signal, and u [5] is the cosine function carrier signal.

The switch module combines the first and second phase-matched amplitude-modulated carrier signals to produce a summed phase-matched amplitude modulated carrier signal, and the amplifier module applies gain to the summed phase-matched amplitude modulated carrier signal to produce the gain and phase compensated motor control command signal. The gain is based on the gain adjustment value (| TF (f) ^-1 |) corresponding to the value of the estimated instantaneous angular velocity.

1 shows a perspective view of an exemplary electric rack and pinion steering system (EPS) 10 used in a vehicle. This in 1 Rack and pinion system shown 10 is described in U.S. Patent Application Number 2009/0294206 entitled "Reducing the Effects of Vibration in an Electric Power Steering System (EPS)" filed on May 30, 2008, which is assigned to the assignee of the present invention and which is fully incorporated by reference is included here. For the sake of brevity, here is the description of 1 not be repeated again.

In a conventional EPS system, when the corners of the vehicle are rotated, this results in cornering controls that can cause vibrations in the SW of the vehicle. Controls at the corners of the vehicle are (partly) determined by the periodic rotation of the tire. If the electronic control unit (ECU) (not shown) knows the frequency of the tire and the instantaneous angular position of the tire, the ECU has information it needs to determine the periodic proportion of everything in the subsystem and can, for example, reduce the torque fluctuation ( ie, search and extract the frequency component present in the output signal from the torque sensor). Based on the position of the corners, it is possible to determine the corrections to the motor current necessary to counteract the activations. In particular, when the transfer function of the engine to the system, frequency of the tire and the current angular position of the tire are known by observing the one-corner drive, the drive can be counteracted by introducing a periodic signal from the motor to drive from the corner counteract.

This in 1 illustrated electric rack and pinion steering system (EPS) 10 contains wheel sensors 98 which are used to determine the wheel speed and / or the relative angular position of the wheel. These wheel sensors 98 are coupled to an electronic control unit (ECU) (not shown) via wire connections. If such wire connections exist, the ECU has direct access to signals proportional to the angular movement of the tire. The ECU may use these signals to determine the absolute angular position of the tire, and then convert the angular position of the tire into an angular velocity of the tire via differentiation. These signals may then be used to determine the frequency needed to cancel the periodic vibrations produced by one or more wheel assemblies or corners.

However, in most vehicles today, such wire connections to the EPS controller are not available and insertion The same would require considerable effort, because new sensors 98 and, or additional wires and, or additional electronics would be needed. Additionally, most, if not all, of the existing electrical control plugs have the space capacity to readily accept additional pins to accommodate the extra wires, so new pins would have to be added to the plugs to accommodate the new wire connections. In short, this deviates from the standard hardware and is expensive.

The disclosed embodiments eliminate the need for additional sensors 98 , Wiring and additional electronics as described above. A steering system 200 for an EPS system of a vehicle including an electronic control unit (ECU) ( 282 ) containing a SWV suppression control module will now be described with reference to FIGS 2 and, respectively, 3-4.

Before describing these embodiments, it will be noted that although the embodiments of the present invention are similar to any conventional rack and pinion EPS system similar to that of FIG 1 As will be apparent to those skilled in the art, it will be appreciated that the embodiments of the present invention may be applied to a conventional column EPS system. In other words, the disclosed embodiments have no particular dependency on the type of EPS system and are equally applicable to rack EPS systems as well as column EPS systems.

2 is a block diagram of a steering system 200 for an EPS system of a vehicle according to some of the disclosed embodiments. The SWV suppression control module 280 It is designed to reduce or "dampen" SWVs in the steering wheel of the vehicle.

The steering wheel resistance (SWI) (Z _SW (s)) 210 Acts on the dynamic loading or resistance in the steering wheel, which resists the combination of driver torque and steering column torque. The steering wheel resistance (SWI) (Z _SW (s)) 210 varies as a function of frequency, contained in the LaPlace variable s. The (SWI) (Z _SW (s)) 210 not only contributes to the sluggish resistance of the steering wheel, but also takes into account hand / arm load on the steering wheel as well as other effects of steering column bearings and conditions between sliding liners of the column. block 215 represents the angular displacement (θ _{above_sensor} ) of the steering wheel relative to its axis of rotation (ie, the steering wheel angle). During noticeable vibrations, the dynamic angular displacement (θ _{above_sensor} ) 215 be observed as parts of one degree.

The system 200 contains a path between block 250 and differentiation block differencing block 220 ,

There is a difference between the angular displacement (θ _{above_sensor} ) 215 the part of the EPS system located "above the torque sensor" and the angular position (θ _{below_sensor} ) 290 of the part of the EPS system located "below the torque sensor" and for linear-elastic material, which is typical for the torque sensor, it will be proportional to the torque transmitted by the sensor. There are many sensors for generating electrical, torque-responsive, signals that can be successfully used in the disclosed embodiments. For example, those based on angular offsets at adjacent attachment end points of a calibrated torque element determine relative rotations between the attachment endpoints, in response to torque, magnetostrictive transmission, those responsive to shearing strain. Sensors commonly used in EPS that produce a consistent relationship between torque and generated electrical signal can be used reliably and effectively in the disclosed embodiments. These, and others, will give non-zero dynamic differences in the relative angular displacement at the upper and lower closest sensor locations, in response to applied dynamic torque, and constant at relative misalignments as their torque increases. There is no intention to diminish its generality in the illustrations, which here maintain confidence in the difference in angular misalignments at locations "above the torque sensor" and "below the torque sensor". These particular mechanization and elaborations are merely intended to assist illustration and do not preclude any sensor suitable for electrical transmission of monotonic torque. Rack and pinion EPS systems such as the 1 As shown, elements disposed above the torque sensor may include the steering wheel (SW), steering column, I-spindle, and flexible couplings, etc., and elements disposed below the torque sensor may include the steering pinion, rack, EPS motor, tie rods, and corner damping , In contrast, in steering column EPS systems, parts of the steering column are moved down to below the torque sensor and the EPS motor is shifted to the steering column such that elements disposed below the torque sensor, for example can contain the EPS motor, I-spindle, flexible couplings, tie rods and corner damping. Regardless of whether it is a rack and pinion EPS system or a steering column EPS system, one common feature is that the EPS motor is below the torque sensor on both types of EPS systems.

For predictive considerations, when the driver turns the SW, this causes a mechanical torque to be applied to a rod that is coupled to the SW. This has a differential shift or an angular difference 222 between the angular position (θ _{below_sensor} ) 290 and the angular displacement (θ _{above_sensor} ) 215 result. The differentiation block 220 represents the angular difference between the angular position (θ _{below_sensor} ) 290 and the angular displacement (θ _{above_sensor} ) 215 and gives an angle difference signal 222 from. The angle difference signal 222 represents the angular difference between the angular position (θ _{below_sensor} ) 290 and the angular displacement (θ _{above_sensor} ) 215 represents.

The angle difference signal 222 is provided to (or communicates via) a mechanical path 230 , an electrical path 235 and the SWV suppression control module 280 , As will be described below, the SWV suppression control module implements 280 Control logic in 3 to a gain and phase compensated motor drive control signal 291 to generate an EPS motor in the electrical path 235 controls to reduce SWVs in the SW.

The mechanical path 230 represents the mechanical part of the EPS system, along the mechanical path from the torque sensor to the tie rods (everything outside the tie rods is a corner and is not part of the mechanical path 230 ). The mechanical path 230 transmits the driver's side and reactions to the opposite driven corner torques. In a rack and pinion EPS system, the driver torque is an action or reaction that is applied across the pillar and the steering gear. The steering gear is in contact with the rack and is therefore kinematically coupled to the translatory movement of the rack.

The electrical path 235 includes the torque sensor signal and the electric motor (not shown). The torque sensor signal represents the angular difference 222 as an input that controls the electric motor. In front-wheel drive behavior, the input indicates how much torque the driver exerts on the SW and may be proportional to the torque exerted by the driver on the SW. In response to this input, the electric motor rotates to a motor assist torque 236 to create. The engine assist torque 236 represents the additional torque generated by the EPS electric motor used to assist the driver in controlling the vehicle. In this way, and taking into account front-wheel drive characteristics, the electric motor (not shown) assists the driver in providing the torque required to steer the vehicle.

torques 232 . 236 are in the summing up block 240 summed up to accumulated torque 242 to generate that for block 250 provided. The accumulated torque 242 represents the combined torque that allows steering and responds to corner loading by the tie rods. Consequently, put the torque 232 and the engine assist force 236 an accumulated torque 242 ready to be used to overcome or respond to the corner loads of the vehicle. This torque 242 For example, in a rack and pinion EPS system, it is applied to the rack to effect the steering of the corners, while in a column EPS system, the torque is applied 242 is applied to the steering column (below the torque sensor) to effect the steering of the corners.

block 250 represents the resistance (Z _{CORNER (s)} ) of the left front corner and the right front corner as a function of the frequency. The resistance 250 is dynamic by nature and is based on the mass of the corner, the cornering resistance, the corner damping and the dynamic properties of the tire, among others.

The blocks 260 . 265 Excitations on the left front corner of the vehicle and, correspondingly, the right front corner of the vehicle, also referred to here as the left front corner excitation 260 and as the right front corner excitation 265 be designated. These excitements 260 . 265 can originate from a variety of sources, including, but not limited to, tire and / or wheel unevenness, any imbalance in any of the rotating parts of the corner, etc. The excitations 260 . 265 angular displacement (θ _{above_sensor} ) at the corresponding corners 215 which propagates to the steering wheel and which can be noticed as SWVs by the driver.

Feedback loop

Based on these inputs carries block 250 to the angular position (θ _{below_sensor} ) 290 the portion of the EPS system located below the torque sensor. For example, in a rack EPS system provides block 290 the angular position of the steering gear, while in a steering column EPS system block 290 represents the angular position of the steering column below the torque sensor, on the motor side of the EPS system.

When the excitement 260 . 265 from the left front tire and the right front tire, without any mechanism to suppress their effects, are fed to the corresponding corners, this angular displacement (θ _{above_sensor} ) 215 cause what can be noticed as SWVs by the driver. In order to reduce these SW vibrations generated on the SW, it is helpful to understand the relationship between the excitations applied to the corners 260 . 265 and to characterize the vibration effects occurring on SW.

control block 285 contains the electrical path 235 and the ECU 282 containing the SWV suppression control module 280 contains.

When the angle difference 222 as close as possible to zero, then the torque of the torque sensor will also go to zero, since the two are in linear relationship to each other, and if the torque of the torque sensor goes to zero, then the angular displacement (θ _{above_sensor} ) 215 go to zero.

As such, the SWV suppression control module generates 280 (more detailed in 3 shown) the gain and phase compensated motor drive control signal 291 to adjust the current supplied to the EPS motor by the angle difference 222 to reduce. Specifically, if the SWV suppression control module 280 is operated at a particular, interesting frequency, the gain and phase compensated motor drive control signal 291 the EPS motor via the electrical path 235 supplied so that the EPS motor is supplied with the correct current to create a condition that the angular displacement (θ _{above_sensor} ) 215 will reduce. In short, if completely successful and for illustrative _purposes only, it will require that the control logic functions must ensure that the magnitude of the angular position (θ _{below_sensor} ) 290 and the angular position (θ _{above_sensor} ) 215 are approximately the same, so their difference 222 is close to zero (eg, as close as possible to zero) to give approximately zero torque generated at the SW. As a result, SWVs can be suppressed / attenuated so that the operator of the vehicle experiences minimal or no vibration at the SW at the particular operating frequency of interest, regardless of the particular value of SWI (Z _SW (s)). 210 , It is noted that any low-frequency SW movements such. For example, those typical of steering maneuvers are nearly unaffected by the SWV suppression control module 280 while operating at normal highway speeds.

To make sure the difference 222 between the angular position (θ _{below_sensor} ) 290 and the angular position (θ _{above_sensor} ) 215 is reduced (so that SWVs can be reduced), the electrical path 235 and SWV suppression control module 280 be operated at the correct periodic frequency. Determining the correct frequency requires knowledge of the angular velocity and position of the tires over a period of time. As with respect to 3 may be described, the SWV suppression control module 280 can be used to determine the correct frequency even in the absence of wire connections to the front wheels to determine their angular velocity and position.

To further elaborate, ABS pulse train information accessible to the ECU via the in-vehicle LAN may be used to estimate the angular velocity and position of the tires over a period of time, and these estimates may then be used to determine the proper frequency , For example, in one implementation, ABS pulse train information is routinely communicated over the LAN indicating that a tire has been rotating for a certain amount of time over a certain angular movement. The ECU may use this information to calculate an estimated angular velocity of the tire and then integrate the estimated angular velocity of the tire to calculate an estimated angular position of the tire.

More specifically, block 270 is an incremental angular position encoder 275 for the right front tire (without absolute reference). The encoders 270 . 275 generate incremental angular position information 277C . 277D high resolution corresponding to the left front wheel and, correspondingly, the right front wheel. The incremental angular position information 277C . 277D high resolution contains pulses, typically the brake ECU 273 be communicated. The brake ECU 273 processes these signals and communicates relevant information incremental rotation angle 277A . 277B on the LAN 279 , generally at coarser intervals than those at 277C . 277D accessible and correspondingly coarser time spans, while the EPS control 282 accessible. In one embodiment, the angular position information 277A . 277B Pulse sequence information of the anti-lock brake system (ABS) (eg, wheel position measurements and timestamps). As will be described in more detail below, the FIG ECU 282 Angular position information 277A . 277B and uses these pulses to determine / estimate angular velocity and angular position of the tire. As will also be described below, the SWV suppression control module 280 Use the estimated angular velocity and estimated angular position of the tire (along with other amplitude and phase adjustments described below) to ensure that the SWV suppression control module 280 works on the right frequency to make sure that the SWV suppression control module 280 the angular difference 222 can reduce.

However, because the angular velocity and tire position, derived from intermittent information, are estimates, they do not represent the precise angular frequencies that are identical to those of the tires (ie, the estimates will occur at frequencies close to, but not identical to, the tire frequencies are).

As such, the SWV suppression control module 280 ( 3 ) requires that there be periodic content in an output signal 351 of a dynamic torque sensor at an angular frequency of interest and then detecting the gain and phase compensated motor drive control signal 291 created (at this periodic frequency), which is designed to reduce the periodic fluctuations. More particularly, the controller extracts information from ABS pulse trains provided via the vehicle LAN to generate current tire position and angular velocity estimates used to generate carrier signals, which are then processed to extract periodic variations in the torque sensor. The estimated tire frequency is also applied to a stored inverse engine drive-to-sensor torque transfer function that is a function of the tire frequency to generate phase and gain adjustments that may be applied to carrier signals along with the extracted periodic variations of the torque sensor generate gain and phase compensated motor drive control signal. The gain and phase compensated motor drive control signal 291 is returned to the electric motor to suppress the periodic content in the output signal of the torque sensor to suppress vibrations in the steering wheel of the vehicle.

3 is a block diagram illustrating an implementation of the SWV suppression control module 280 from 2 according to some of the disclosed embodiments. 4 is a flowchart that is a procedure 400 for attenuating (ie, reducing / suppressing) SWVs in a steering wheel according to some of the disclosed embodiments. For brevity, the procedure becomes 400 below with reference to 3 describe how to explain different steps of the procedure 400 convert to when in 3 illustrated control architecture applied. however, one of ordinary skill in the art will appreciate that the process 400 on control architectures other than the one in 3 illustrated SWV suppression control module 280 can be applied.

As stated above, the tire angle position information becomes 277A . 277B that has periodic frequency content, regularly over the LAN 279 of the vehicle to the SWV suppression control module 280 communicated. method 400 starts at step 410 where the SWV suppression control module 280 estimated angular velocities and estimated angular position shifts of the front wheels / corners from the angular position information communicated over a LAN 277A . 277B generated.

Regarding 3 can step 410 at the blocks 310 and 320 be implemented as follows. From the LAN 279 of the vehicle receives the estimation module 310 intermittent information regarding the change in the angular position of the tires over a certain time course (for example, a number (N) of pulses obtained over a period of time (T)) for each of the two front tires. The estimation module 310 uses these variables to calculate and estimate the instantaneous angular velocity of each tire and then calculates a weighted average of the instantaneous angular velocities by an estimated instantaneous angular velocity signal 311 to generate. The estimated instantaneous angular velocity signal 311 represents the estimated instantaneous angular velocity of a virtually rotating tire, also referred to herein as the "estimated tire frequency". A is the estimated tire frequency 311 is only estimated using intermittent data from the LAN, it can only be considered "close" to the current tire frequency.

First stage: carrier signal generation and superimposition

The estimated tire frequency signal 311 (or the estimated angular velocity signal 311 ) is then integrated (in the integrator module 320 ) to an estimated angular position signal 321 which corresponds to the estimated angular position of the virtual tire.

At the step 420 creates the SWV suppression control module 280 based on the estimated angular position signal 321 , two sinusoidally shaped carrier signals 331 . 336 at the estimated tire frequency 311 which is near the current tire frequency. In particular, a sine-function carrier signal 331 and a cosine function carrier signal 336 be at the estimated tire frequency 311 generated (ie, at the periodic frequency corresponding to the estimated angular velocity of the virtual tire). In other words, the carrier signals 331 . 336 serve as fundamental frequency oscillators at the angular frequency of the virtual tire. The step 420 can, with reference to the 3 , at the blocks 330 and 335 be implemented as follows.

The sine function generator module 330 receives the estimated angular position signal 321 and generates a sine-function carrier signal 331 at the periodic frequency, with the estimated angular velocity 311 corresponds to the virtual tire. Similarly, the cosine function generator module receives 335 the estimated angular position signal 321 and generates a cosine function carrier signal 336 at the periodic frequency, with the estimated angular velocity 311 corresponds to the virtual tire. The cosine function carrier signal 336 is opposite to the sine function carrier signal 331 90 degrees out of phase. The sine function carrier signal 331 and the cosine function carrier signal 336 are a set of coincident and 90 degree generators (ie, generally referred to as in-phase and out-of-phase wave generators at the frequency of the periodic noise signal).

The sensor 350 generates a periodic electrical torque signal 350a that is representative of or proportional to the periodic mechanical torque sensed by the torque sensor (ie, that represents torque occurring at the torque sensor). sensor 350 conducts the periodic electrical torque signal 350a to a bandpass filter 351 , while a filtered torque signal 352 generating. In one embodiment, the cutoff frequencies become 10 Hz for the high pass and 20 Hz for the low pass of this bandpass filter 351 established. The exact value of these frequencies will vary for each vehicle application, and the 10 Hz, 20 Hz corner frequencies are exemplary of a non-limiting embodiment. That of the sensor 350 originating periodic electrical torque signal 350a represents the measured dynamic steering wheel torque and can also be called "torque signal" here 350a be designated. The torque signal 350a has at the frequency of the carrier signals 331 . 336 periodic content; however, the amplitude is the periodic component of the torque signal 350a and the phase shift between the periodic electrical torque signal 350a and the carrier signals 331 . 336 unknown and must by subsequent actions of the SWV suppression module 280 be determined. In one implementation, the sensor receives 350 the mechanical in-line torque, captured between the steering wheel and the gearbox of the EPS motor. For a column EPS system, the sensor is 350 typically installed between the steering wheel and the transmission of the engine to the steering column (ie, integrated into the steering column). In a rack EPS system, the sensor is 350 typically installed on the input shaft to the steering gear (ie, integral with the steering gear mounted outside the passenger cabin).

At step 430 performs the SWV suppression module 280 a superposition function by individually mixing the carrier signals 331 . 336 with the filtered torque signal 352 through to mixed signals 341 . 346 to generate accordingly. With reference to 3 can the step 430 at the blocks 340 . 345 be implemented as follows.

The mixer module 340 mixes (ie, takes the product of) the sine function carrier signal 331 and the filtered torque signal 352 to a first mixed sinusoidal signal 341 to generate that of the mixed transverse component of the sensor module 350 observed signal corresponds.

Similarly, the mixer module mixes 345 (ie, the product of) decreases the cosine function carrier signal 331 and the filtered torque signal 352 to a second mixed cosine signal 346 to generate that of the mixed longitudinal component of the sensor module 350 observed signal corresponds.

At the step 440 extracted as SWV suppression module 280 the content of the mixed signals 341 . 346 , With reference to 3 can the step 440 at the blocks 348 . 355 . 368 and 388 be implemented as follows.

Before describing the operation of the extraction modules 348 . 355 Now, an explanation will be made of a vehicle forward acceleration gain modulator module 385 and a steering wheel adjustment gain modulator module 388 provided, which are used to determine the characteristics of the extraction modules 348 . 355 to change. The vehicle forward acceleration amplification modulator module 385 receives vehicle speed information over a bus, calculates vehicle acceleration, and generates a first compensation input (eg, controller gain and, optionally, filtering characteristics) of the first extraction module 348 and the second extraction module 355 to receive interfering signals follow, which are based on speed fluctuations during acceleration / deceleration of the vehicle. The steering wheel adjustment boost modulator module 388 receives steering wheel position signals and generates second compensation inputs (SWA, d (SWA) / dt) used to control the control characteristics of the first extraction module 348 and the second extraction module 355 change the recorded table entries during steering. Before the adjustments from the vehicle forward acceleration gain modulator module 385 and the steering wheel adjustment gain modulator module 388 be applied, the conditions by a hysteresis threshold / Persistenzschwellwertmodul 386 directed to ensure that the changing states of the extraction modules 348 . 355 not be exposed to jitter or irregular transitions over desired time intervals. "Jitter" or unwanted relatively frequent and abrupt transition reversals near a fresh threshold is overcome by introducing a hysteresis, as those skilled in the art know. Transitional switching can also be achieved with accompanying time delay, thereby indicating a delayed change from what was detected by the fresh threshold, here referred to as persistence; this time-delayed transition switching is also known to those who are from the subject. An example of an extreme change in control action of increased response time may include holding the value of the extractor output at the start of steering and maintaining that value until the steering ends. Those skilled in the art will understand the need to manage the duration of these "hold" operations, as long stoppage of control action may end in inability to track or follow the changes in periodic arousal. These varying excitations are generally related to the difference in rotational speeds of the two front tires and are understood when conditions dictate (eg, during simultaneous steering and accelerating, using spare tires, different tire sizes between the front tires, different tire wear conditions). These conditions can be detected in the normal pattern of amplitude modulation of the sensor and compensation torques, and short duration amplitude modulations must be accompanied by only a brief stoppage of processing action.

At the blocks 348 . 355 become the mixed signals 341 . 346 processed to extracted signals 362 . 364 to create. The mixed sine wave signal 341 and the mixed cosine signal 346 may include different frequency content in the filtered torque signal 352 available. Relatively prolonged processing of the mixed sinusoidal signal 341 and the mixed cosine signal 346 Helps to reject any frequency content present in these signals which is not attributable to the desired periodic torque sensed.

Each of the extractios modules 348 . 355 implements a proportional-integral-derivative submodule (PID submodule) operating on the mixed sine signal and, correspondingly, the mixed cosine signal along with optional low pass filtering. Each PID submodule contains three separate parameters (in 3 represented as triangles): the proportional value (P), which depends on the current instantaneous input, the integral value (I), which depends on the accumulation of past inputs, and the derivative value (D), which is the difference between the current instantaneous input and the depends on previous inputs. The proportional value (P) determines the response to the current instantaneous input, the integral value determines the response based on the sum of the most recent inputs, and the derivative value determines the response based on the rate at which the input has changed. The weighted sum of these three operations is used to adjust the drive. The PID parameters used in the calculation can be set according to input parameters that depend on the specific system. By setting the three constants in the PID submodule, the PID submodule can provide control activity designed for specific requirements. Some implementations may require using only one or two of the PID modes to provide the appropriate system control. This is accomplished by setting the gain of unwanted control outputs to zero. In the absence of the corresponding submodule activities, a PID submodule will be referred to as a PI, PD, P, or I submodule.

The first extraction module 348 receives the first mixed sine wave 341 , the first adaptation input from the vehicle x acceleration amplification modulator module 385 , the second adaptation inputs from the SWA amplification modulator module 388 and the state detection output of the threshold module 386 , Based on these inputs, the first extraction module processes 348 only the amplitude of the frequency content in the filtered torque signal 352 which is in phase with (and at its particular frequency) the sine function carrier signal 331 to an extracted sine wave signal 362 to generate / extract, which is predominantly a relatively longer term average of the first mixed sine signal 341 is. The processing includes multiplying the integral of the mixed sine signal 341 with a constant, the amplitude of the mixed sine signal 341 with a second constant, and the derivative of the mixed sine signal 341 with a third Constant. These constants may change depending on the inputs from the vehicle forward acceleration gain modulator module 385 and the steering wheel adjustment (SWA) gain modulator module 388 polled at times by the threshold module 386 , The extracted sinewave signal 362 represents the "strength" or amplitude of the filtered torque signal 352 which is in phase with the sine function generator module 330 , adapted to minimize interference with operational events.

In one embodiment, the first extraction module contains 348 a first proportional-integral-derivative (PID) submodule (represented by the three triangles). The first proportional-integral-derivative (PID) submodule receives customizable input parameters from modules 385 . 386 . 388 and scales the mixed sine signal 341 by applying respective gains of proportional, integral, and derivative gain blocks to produce a proportional-scaled sine signal, an integral-scaled sine signal, and a derivative-scaled sine signal. In one embodiment, the respective gains of the gain blocks may be based on the adaptation input parameters from the modules 385 . 386 . 388 be varied.

Similarly, the second extraction module receives 355 the second mixed cosine signal 355 , the first adaptation input from the vehicle x-acceleration module 385 , the second adjustment entries from the SWA module 388 and the state detection output of the threshold module 386 , The second extraction module 355 contains similar gain blocks as the first gain module 348 , and for the sake of brevity, these details become the second extraction module 355 not be repeated here. Based on the inputs processed by the second extraction module 355 only the amplitude of the frequency content of the filtered torque signal 352 which is in phase with (and at its particular frequency) the cosine function carrier signal 336 to the extracted cosine signal 364 of the second mixed cosine signal 346 to generate / extract, which is predominantly a relatively longer term average of the second mixed cosine signal 346 is. The processing includes multiplying the integral of the mixed cosine signal 346 with a constant, the amplitude of the mixed cosine signal 346 with a second constant, and the derivative of the mixed cosine signal 346 with a third constant. These constants may change depending on the inputs from the vehicle forward acceleration gain modulator module 385 and the steering wheel adjustment (SWA) gain modulator module 388 polled at times by the threshold module 386 , The extracted cosine signal 364 represents the "strength" or amplitude of the filtered torque signal 352 which is in phase with the cosine function generator module 335 , adapted to minimize interference with operational events.

In one embodiment, the first extraction module contains 348 optional filters (ie, a filter coupled to each triangular gain block of the PID submodule) and an adder coupled to each of the filters. The second extraction module 355 may also contain a similar adder and filter. In one embodiment, the processed signals may optionally be within the blocks 348 . 355 low-pass filtered to extract the low frequency content (ie, amplitudes or envelopes) of the processed signals produced by the P, I, D gain blocks.

For example, with regard to the first extraction module 348 , an optional filter is provided at the output of each gain block for the proportionally-scaled sine signal, the integral-scaled sine signal, and the derivative-scaled sine signal. The filters are configured to extract low frequency content from the proportional scaled sine signal, the integral scaled sine signal and the derivative scaled sine signal to generate a filtered proportional scaled sine signal, a filtered integral scaled sine signal and, correspondingly, a filtered derivative scaled sine signal. The adder sums the filtered proportional scaled sine signal, the filtered integral scaled sine signal, and the filtered derivative scaled sine signal to obtain a first extracted signal 362 which is a weighted-combined version of the filtered proportional scaled sine signal, the filtered integral scaled sine signal, and the filtered derivative scaled sine signal. Similarly, the second extraction module generates 355 a second extracted signal that is a weighted-combined version of the filtered proportional scaled cosine signal, the filtered integral scaled cosine signal, and the filtered derivative scaled cosine signal. For brevity, here are the details of the second extraction module 355 not be repeated.

The gain constants and filter properties used in the modules 348 . 355 used as well as those in the modules 351 . 382 are adjustable and may be different for each vehicle module and type and adjusted during vehicle development to maximize driver satisfaction. Not all filters in these modules need to be used. In fact, using too many filters can slow the system response too much and adversely affect the stability limit. Any changes that are reflected in the module 348 constants or filter properties should also be applied identically to module 355 be applied.

The multiplexer module 368 multiplexes the extracted sine signal 362 and the extracted cosine signal 364 to a multiplexed signal 369 to create. As will be described below, the multiplexed signal becomes 369 the mixer modules 370 . 375 provided.

Motor Drive to Sensor Torque Transfer Function and Inverse Motor Drive to Sensor Torque Transfer Function

Before performing procedures 400 a transfer function (TF (f)) (represented by block 450 ). The transfer function (TF (f)) represents the transfer function from the EPS motor to the sensor 350 and characterizes or quantifies the dynamic influence or effect of the motor drive command on the sensor torque. The transfer function (TF (f)) is a function of the estimated wheel frequency 311 , f, from the estimation module 310 provided. In other words, the estimated transfer function (TF (f)) defines how the command drive to the engine is that of the sensor 350 detected torque influences. The transfer function (TF (f)) is provided by exciting the system with known motor drive inputs at different frequencies and measuring the sensor torque outputs. The motor drive input and sensor torque output signals are then windowed and Fourier transformed. The transformation of the sensor torque output is then divided by the transformation of the motor drive input. The resulting frequency base complex function will predict the behavior of the sensor torque output on an input motor drive input. Those skilled in the art will recognize other potential methods, such as applying auto and cross spectral densities and their means over time, to estimates of transfer functions in the presence of spurious signals. The above explanation is merely a simplification of these methods for the purpose of explanation. In one implementation, the estimated transfer function (TF (f)) becomes one in the memory of the SWV suppression control module 280 stored look-up table (LUT). The transfer function (TF (f)) is specific to the particular crafting / modeling of the particular vehicle and may be modified / updated over its lifetime by adaptive learning.

Based on the estimated transfer function (TF (f)), an estimated inverse transfer function table (TF (f) ^-1 + line compensation (f)) 312 calculated in the blocks 370 . 375 . 390 from 3 is used as follows. table 312 FIG. 13 is a discretized representation of the line balance transfer function that may be used to determine which system input is necessary to give a desired system output.

Second stage: using estimated tire frequency, inverse motor drive-to-sensor torque transfer function, and carrier signals to generate a gain and phase compensated motor drive signal

Based on the estimated tire frequency 311 , f, generates table 312 a complex signal containing (1) a carrier phase angle adjustment value (angle (TF (f)) ^-1 + line balance (f)) 314 , the first mixer module 370 and the second mixer module 375 and (2) a gain adjustment value (| TF (f) ^-1 |) 316 , the reinforcing module 390 provided. In other words, the obtained inverse transfer function table (TF (f) ^-1 + line balance (f)) 312 is used to obtain values for estimating carrier phase angle adjustment value (angle (TF (f)) ^-1 + line balance (f)) 314 , applied to the first mixer module 370 and the second mixer module 375 , and (2) the gain adjustment value (| TF (f) ^-1 |) 316 , used in the reinforcement module 390 which are used to amplify and phase-compensated drive signal 291 in the reinforcement module 390 so that SWV reductions occur with adequate vibration stability limitation. The carrier phase angle adjustment value (angle (TF (f)) ^-1 + line balance (f)) 314 represents a carrier angle change to be applied at the selected frequency. The gain adjustment value (| TF (f) ^-1 |) 316 represents a gain to be applied (at the selected frequency) equal to the inverse or reciprocal of the TF gain at the periodic corner frequency.

At step 460 uses the suppression control module 280 a carrier phase angle adjustment value signal 314 showing the angle of the inverse TF (f) ^-1 and line balance information for improved stability limit (provided in block 312 ) to the phase of the carrier signals 331 . 336 to adapt and to generate phase-matched carrier signals. The phase-matched carrier signals are in 3 not shown as in blocks 370 . 375 generated internally. The phase-matched carrier signals (in 3 not shown) are then amplitude modulated by the amplitudes (or sheaths) which are combined via a combined output signal 369 be provided to phase-matched amplitude modulated carrier signals 371 . 376 accordingly. Regarding 3 can take steps 460 and 470 at the blocks 312 . 370 . 375 be implemented as follows.

A first mixer module 370 receives the sine function carrier signal 331 (from the sine function generator module 330 ), the carrier phase angle adjustment value signal 314 (at the selected frequency) and the multiplexed signal 369 , The first mixer module 370 modifies the sine function carrier signal 331 based on the carrier phase angle adjustment value signal 314 and the line trim information to produce a phase matched sine function carrier signal (not shown). The first mixer module 370 also receives the combined output signal 369 (the content of the extracted sine signal 362 and content of the extracted cosine signal 364 contains). The first mixer module 370 amplitude modulates the phase matched sine function carrier signal (not shown) based on the envelopes of the extracted signals 362 . 364 to a phase matched amplitude modulated sine carrier signal 371 which will interfere with an interfering signal due to drives 260 . 265 caused at the corners. In one implementation, the first mixer module transforms 370 its input signals by performing the following operation: (cos (u [4]) · u [2] - sin (u [4]) · u [3]) · u [1] Equation (1), where u [1] is the sine function carrier signal 331 is, u [2] the extracted sinusoidal signal 362 is, u [3] is the extracted cosine signal, and u [4] is the carrier phase angle adjustment value signal 314 is.

Similarly, the second mixer module receives 375 the cosine function carrier signal 336 (from the cosine function generator module 335 ), the carrier phase angle adjustment value signal 314 (at the selected frequency) and the multiplexed signal 369 , The second mixer module 375 modifies the cosine function carrier signal 336 based on the carrier phase angle adjustment value signal 314 and the line trim information to produce a phase matched cosine function carrier signal (not shown). The second mixer module 375 also receives the combined output signal 369 (the content of the extracted sine signal 362 and content of the extracted cosine signal 364 contains). The second mixer module 375 amplitude modulates the phase-matched cosine function carrier signal (not shown) based on the envelopes of the extracted signals 362 . 364 to a phase-matched amplitude modulated cosine carrier signal 376 which will interfere with an interfering signal due to drives 260 . 265 caused at the corners. In one implementation, the second mixer module transforms 375 its input signals by performing the following operation as shown in equation (2): (cos (u [4]) · u [3] - sin (u [4]) · u [2]) · u [5] Equation (2), where u [2] is the extracted sine signal 362 is, u [3] the extracted cosine signal 364 is, u [4] the carrier phase angle adjustment value signal 314 (at selected frequency) and u [5] is the cosine function carrier signal 336 is.

At step 480 combines the SWV suppression control module 280 the phase matched amplitude modulated carrier signals 371 . 376 , For example, as in 3 shown receives the summing module 380 the phase matched amplitude modulated carrier signals 371 . 376 and combine them to produce a summed phase-matched amplitude modulated carrier signal, which then becomes a bandpass filter module 382 is passed to a filtered summed phase-matched amplitude modulated carrier signal 383 to create. For example, the cutoff frequencies of the bandpass filter are 10 Hz for the high pass and 20 Hz for the low pass. The exact value of these frequencies will vary for each vehicle application. The filtered summed phase-matched amplitude modulated carrier signal 383 has the correct phase, so that when applied to the EPS motor, torque generated by the EPS motor acts on dynamic forces generated by the corners. As a result, the interfering signal on the sensor 350 in the torque signal 351 that through the sensor 350 is output, reduced / attenuated.

At the step 490 then becomes the filtered summed phase-matched amplitude modulated carrier signal 383 again amplitude modulated in accordance with the magnitude of the inverse TF, around the gain and phase compensated motor drive control signal 291 near the periodic frequency. For example, multiply as in 3 shown, the reinforcement module 390 the filtered summed phase adjusted amplitude modulated carrier signal 383 with the size of the estimated inverse transfer function (| TF (f) ^-1 |) of the table 312 to the gain and phase compensated motor drive control signal 291 (at the periodic frequency), which is fed back and applied to the electric motor (not shown). The reinforcement module 390 applies appropriate gain to the filtered summed phase-matched amplitude modulated carrier signal 383 (which is proportional to the inverse of the magnitude of the estimated inverse transfer function (| TF (f) ^-1 |)), so that the gain and phase compensated motor drive control signal 291 the interference signal on the torque sensor extinguished without causing the system to become unstable. The gain and phase compensated motor drive control signal 291 suppresses the in the output signal 351 watched by the sensor 350 generated periodic content, so that the angular difference is reduced and SWVs are attenuated at the SW (eg in the block 215 from 2 ). The gain and phase compensated motor drive control signal 291 affects the output signal 351 mechanically by causing the engine (and the torque it generates) to dynamically react to tie rod forces and those on the sensor 350 to reduce acting dynamic loads and so in the sensor 350 recorded periodic content. The process then jumps to step 410 back.

The SWV suppression may be implemented to suppress one or more harmonic periodic contents otherwise detected by the driver. The above is descriptive of a single harmonic, namely the first harmonic, but the procedure is equally on the 2nd, 3rd, 4th harmonics, among other harmonics. To effectively suppress other than the first harmonic, become the sine function generator module 330 and cosine function generator module 355 set to the harmonic frequency sought to be suppressed. For example, if the second harmonic frequency is sought, this results in 330 and 335 to operate at twice the frequency of the first harmonic; For example, if the third harmonic frequency is sought, this results in 330 and 335 to operate at three times the frequency of the first harmonic, and so on. Decisions on the harmonic to suppress can be made based on the vehicle speed, since the probability of spurious SWVs occurs when the excitation frequency coincides with a resonant frequency of the vehicle, such as that of the damping system, the steering system, among others. For example, the second harmonic may be annoying, especially at relatively low speeds, e.g. B. 35 mph, while the first harmonic be disturbing, especially at relatively higher speeds, z. 70 mph. The relationship between interfering harmonics and velocity stems from these dynamic resonance conditions, resulting in disproportionately larger SWV when the frequencies of excitation and resonance coincide. In cases where active harmonics are present and uncomfortable at the same time, the SWV suppression control module may 280 with minor changes for each harmonic of interest. If so desired, the blocks can 310 . 312 . 320 . 350 with corresponding signals 277A . 277B . 311 . 314 . 316 and 321 be shared with and shared with the multiple SWV suppression control modules. In this case, the gain and phase compensated motor drive control signals become 291 of the various suppression control modules and superimposed with the motor drive commands in a manner identical to that of the descriptions expressed in the foregoing description. Simultaneous operation of multiple harmonics suppression will not result in undesirable interference between the harmonic drive content at reasonable operating speeds, e.g. When operated at more than 30 mph due to relatively different frequencies of the respective harmonics of the SWV rejection frequencies and the relatively high "Q" notch filters resulting from the suppression. ("Q", or "quality factor" are, for example, in Shock and Vibration Handbook, 3rd Edition, Cyril M. Harris, page 2-15, McGraw-Hill Book Company, 1987 . ISBN 0-07-026801-0. ) Identification of targeted harmonic rejection frequencies, disturbing velocities, associated cutoff frequencies of the various filters are specific to individual vehicle makes and models in manufacturing facilities and are very similar to the methods used to tune the EPS for conventionally assisted implementation as well as other electronic and electrical control devices such as ABS, TCS and ESC. As such, they are well known to those skilled in the art.

It may also prove advantageous to turn off or block SRS compensation during operation of the vehicle at times when it appears unnecessary or dangerous, such as when the vehicle is in use. At speeds insufficient to produce otherwise detectable SWV while operating on bumps while expected uncompensated SWV below thresholds of attention, or during extreme speed changes of the tires operating at extreme values of longitudinal slips or combined longitudinal and lateral slipping become. These conditions are further exemplary only and do not exclude other conditions believed to be beneficial in suppressing compensation. In addition, exemplary suppressing or disabling compensation may be performed with the implementation of thresholds for vehicle speed, SWV, and aperiodic vibration amplitudes indicative of rough roads detected within the torque sensor or communicated via LAN from other intelligent ECUSs. Furthermore, in each of the cases listed above and in other, if desired, switching states between active and inactive SRS compensation can be performed by implementing hysteresis switching with or without persistence, thereby avoiding jitter. As a particular example, in the case of turning off SRS compensation based on vehicle speed, the SRS compensation may be turned off below 45 mph if off Speeds below 45 mph, and then shut down below 40 mph if slowing down speeds in excess of 40 mph. These conditional activations and deactivations may be beneficial when considering vibration stability limits, power consumption, and interactions of the SRS compensation actions with other driving behavior, either during other active control engagements (eg, anti-lock brake system control (ABS), traction control (TCS), electronic stability control (ESC), etc .) are relevant. The applications of switching, hysteresis, or others, either with or without persistence, are well known to those skilled in the art, and accordingly, can be implemented immediately.

Accordingly, methods, systems and devices for suppressing steering wheel vibrations (SWVs) have been described that occur within an electric power steering (EPS) system.

Periodic SRS can be damped by using a control system that adopts a SWV suppression control algorithm that runs in the electronic control unit (ECU) of an electronic steering assist (EPS) system of a vehicle. The disclosed SWV suppression techniques utilize existing hardware present in each vehicle with EPS system (eg, EPS motor, EPS torque sensors, wheel speed position sensors, and EPS controls) along with the SWV suppression control algorithm to suppress SWVs ,

The EPS controller uses existing intermittent LAN communications of ABS tone wheel pulse trains to approximate angular position of front corners and then uses this approximation to provide a reliable oscillation reference in the EPS controller. As a result, the need for additional wiring, hardware, or other parts can be eliminated, which can provide a significant competitive advantage unlike other SWV suppression techniques. The SWV suppression controller uses a blending function to extract periodic content in the steering wheel torque sensor signal and then amplitude modulates Co and quad generators with the extracted periodic amplitude. The extracted and modulated content is then applied to the motor torque drive so as to achieve high "Q" notching for expected periodic content. Because the SWV suppression techniques are software-based (and build on existing hardware), these techniques are virtually free. in addition, it has been observed in simulations that as the vehicle travels in the range of about 50 miles per hour to 90 miles per hour, the SWV suppression techniques can be implemented to substantially attenuate / reduce periodic SRS by about 80% at the steering wheel without interfering with frequency bands associated with steering and handling performance. As such, other vehicle performance characteristics and straight-ahead performance are not affected.

5 FIG. 10 illustrates another exemplary embodiment of a control module. FIG 500 suitable for use as the SWV suppression control module 280 in 2 , Various elements of the control module 500 are similar to the corresponding ones above in the context of 2 - 3 described elements and are, accordingly, here in context with 5 not described redundantly. control module 500 contains a damping compensation arrangement 502 which counteracts the SWV suppression, otherwise from the PID submodules of the shell extraction modules 248 . 355 would result. In this regard, in the steady state, the PID submodules can suppress almost all SWVs and depress the measured mixed disturbance torque signals at their inputs; however, in some situations, it may not be desirable to completely subvert the SWVs, or it may be desirable to dynamically adjust the proportion that dampens / suppresses the SWVs. For example, it may be desirable to reduce the proportion of the EPS motor (eg motor 90 ) to save energy, to improve the longevity and / or durability of the EPS motor, or otherwise allow SWVs to be communicated to the steering wheel based on real-time operating conditions learned by the vehicle.

The illustrated attenuation compensation arrangement 502 includes, without limitation, a first low pass filter arrangement 504 , a second low-pass filter arrangement 506 , a first size determination block 508 , a second size determination block 510 , a first summation block 512 , a customizable gain module 514 , an offset-dividing block 516 , a second summation block 518 and a third summation block 520 , The elements of the damping compensation arrangement 502 are suitably configured to offset torque signals 522 . 524 which are subtracted from or otherwise combined with the measured mixed disturbance torque signals 341 . 346 to reduce the proportion to the the control module 500 SWVs attenuates / suppresses based on the current size of the configurable gain provided by the customizable gain module 514 , In this regard, the customizable gain module is 514 , in exemplary embodiments, with a gain control module 540 coupled.

Gain control module 540 may receive inputs indicating various operating conditions for the steering system (eg, gross torque, total usage and possible total wear effects based on total usage, and the like) and / or the gain control module 540 It can receive inputs from different ECUs, such as a brake ECU (eg brake ECU 273 ), or another external control module. Based on the received inputs and the desired performance of the EPS system (allowable operation and damping accounting based on considerations such as operating conditions, power consumption, expected life and vibration suppression requirements of the system), the gain control module generates 540 a control signal 530 that can indicate a desired amount of gain, that of the adjustable gain module 514 which corresponds to the desired extent in which the SWVs are attenuated / suppressed. In this regard, the amount of attenuation / suppression of SWVs may change dynamically based on total usage of cancellation, amount of cancellation, vehicle speed or speed, current operating state of the vehicle, and / or vehicle subsystem (eg, whether or not the brakes are being applied), or other timely operating conditions experienced by the vehicle. In some embodiments, the control signal 530 through the table 312 are provided as a certain output offset gain value based on the estimated instantaneous angular velocity 311 one or more vehicle tires.

In exemplary embodiments, the value may be determined by the adjustable gain module 514 applied 0 to 1 offset gain, with 0 a through the adjustable gain module 514 representing applied gain, which leads to SWVs passing through the control module 500 maximally attenuated / suppressed (eg, substantially zero SWVs communicating with the steering wheel in steady state) and 1 through the tunable gain module 514 representing applied gain, which leads to SWVs passing through the control module 500 minimally damped / suppressed.

As above in connection with 2 - 4 described contains the filtered torque signal 352 the relatively higher frequency components of the torque sensor 350 detected total measured torque 350a which are likely to be attributable to periodic disturbances within the steering system. In exemplary embodiments, the low pass filter arrangement is 504 with the output of the mixer 340 coupled to the mixed cross component 341 the filtered torque signal 352 to receive, and the low-pass filter arrangement 504 lowpass filters the mixed cross component 341 to remove higher frequency components of the mixer components so as to achieve the amplitude of the quasi-envelope of the periodic lateral stall torque. Equivalently, the second low-pass filter arrangement is 506 with the output of the block 345 coupled to the mixed longitudinal component 346 lowpass filter. Consequently, the output of the low pass filter arrangement is 504 a low-pass filtered version of the mixed cross component (quad) 341 during the output of the second low pass filter arrangement 506 a low-pass filtered version of the mixed longitudinal component (co) 346 is. According to one or more embodiments, the cutoff frequency of the low-pass filter arrangement 504 . 506 realized low-pass filter is chosen so that it is less than the oscillator frequency of the mixed components 341 . 346 and in the range of about 0.1 Hz to about 2.0 Hz, and 0.3 Hz in one embodiment, so that the output of a corresponding low-pass filter arrangement 504 . 506 is substantially equal to the average value of the corresponding mixed component 341 . 346 ,

The low-pass filtered versions of the co- and quad components at the outputs of the low-pass filtering arrangements 504 . 506 become the inputs of the first sizing block 508 which computes or otherwise determines the amplitude of the complex coefficient (or vector) represented by the lowpass filtered versions of the co and quad components, for example by calculating the square root of the sum of the square of the lowpass filtered quad component and the square of the lowpass filtered co-component. Consequently, the output of the size determination block corresponds 508 the magnitude of the measured steering wheel torque at the angular frequency corresponding to the vehicle tires, which is attributable to periodic disturbances within the steering system at that angular frequency. For descriptive purposes, the output of the sizing block may be 508 (ie, the magnitude of the measured steering wheel torque at the angular frequency corresponding to the vehicle tire) may alternatively be referred to herein as the measured SWV torque envelope.

The inputs of the second sizing block 510 are with the outputs of the extraction modules 348 . 355 coupled to the extracted envelope signals 562 . 564 receive or otherwise obtain the second size detection block 510 the amplitude of the transversal and longitudinal extracted signals 562 . 564 calculated or otherwise determined complex coefficients (or vector). As above in connection with 2 - 4 described, the extracted signals correspond 562 . 564 in an appropriate combination, with the amplitude of the carrier of the motor torque applied by the EPS motor at the angular frequency corresponding to the tire counteracting the periodic disturbances within the steering system to attenuate SWVs, that is, the amplitude of the disturbance cancellation torque; created by the EPS engine, with the extracted envelope signals 562 . 564 correlated. Consequently, the output of the second sizing block represents 510 is the magnitude of the engine torque cancellation torque component applied by the EPS motor to cancel periodic steering wheel disturbances. For descriptive purposes, the output of the second sizing block may be 510 (ie, the magnitude of the engine torque cancellation torque component applied by the EPS motor) may alternatively be referred to herein as the SWV cancellation torque envelope.

As in 5 is the first summation block 512 with the outputs of the size detection blocks 508 . 510 coupled to the sum of the measured disturbance torque envelope at the angular frequency comprising the wheel tire from the first size determination block 508 and the cancellation torque envelope corresponding to the EPS motor of the second size determination block 510 attributable to be determined. In this regard, the sum of the measured steering wheel interference torque envelope and the cancellation torque envelope corresponds to an estimate of the gross (or total) disturbance torque envelope attributable to periodic disturbances within the steering system from the sensor 350 would be measured if cancellation torque was not applied by the EPS motor.

As described above, the gain module multiplies 514 the gross disturbance torque envelope at the output of the first summation block 512 with a gain factor corresponding to a desired extent by which the SWVs are to be damped / suppressed to calculate or otherwise determine the magnitude of offset torque, that of the measured disturbance torque envelope (eg, at the summation blocks 518 . 520 ) to ensure that the SWVs on the steering wheel (if the gain is not equal to 0) are not completely suppressed. The offset dividing block 516 transforms the offset torque into cross and longitudinal mixed signal components 522 . 524 that are in the same coordinate quadrant as the extracted envelope signals 562 . 564 are, so that the cross and longitudinal mixed signals 522 . 524 at least part of the signals 341 . 346 negate or otherwise extinguish. In this context, the transverse offset torque component signal becomes 522 from the measured lateral torque component signal 341 in the second summation block 518 subtracted and the longitudinal offset torque component signal 524 is from the longitudinal disturbance torque component signal 346 in the third summation block 520 deducted.

To the offset torque component signals 522 . 524 in the corresponding coordinate quadrant receives the offset-dividing block 516 a transformation angle (θ _T ) by computing or otherwise determining the two parameter coordinates of the arctangent (commonly called atan2 or arctan2) of the extracted envelope signals 562 . 564 , For example, the transformation angle can be determined by applying the equation θ _T = arctan 2 (y, x), where y is the value of the cross-extracted envelope component 562 represents and x the value of the longitudinally extracted envelope component 564 represents. The offset dividing block 516 uses the transformation angle to divide the offset torque to the appropriate coordinate quadrant. For example, the transverse offset torque component 522 is calculated by using the equation O _Q = (g × T _G ) sin (θ _T ) and the longitudinal offset torque component 524 can be calculated by using the equation O _C = (g × T _G ) cos (θ _T ) where T _{G is} the estimated gross disturbance torque envelope within the steering system determined in the first summation block 512 , and g is the gain factor applied by the adjustable gain module 514 , Then determines summation block 518 an adjusted cross-fault torque signal 526 as the difference between the mixed measured lateral torque signal 341 and the transverse offset torque signal 522 and summation block 520 determines an adjusted longitudinal noise torque signal 528 as the difference between the mixed measured longitudinal disturbance torque signal 346 and the longitudinal offset torque signal 524 ,

The adjusted transverse breakdown torque signal 526 and the adjusted longitudinal noise torque signal 528 become the corresponding envelope extraction modules 348 . 355 which, in turn, provides the corresponding extracted lateral and longitudinal envelope signals 562 . 564 based on the adjusted disturbance torque signals 526 . 528 (eg at step 440 ) in a similar manner as above in connection with the 3 - 4 with respect to the adjusted mixed signals 341 . 346 described. In this regard, the extracted cross-envelope signal corresponds 562 (alternatively, the extracted cross-envelope component) output by the Querhüllkurvenextraktionsmodul 348 the amplitude envelope of the adjusted cross-fault torque signal 526 and the extracted longitudinal envelope signal 564 (alternatively, the extracted longitudinal envelope component) output by the longitudinal envelope extraction module 355 , corresponds to the amplitude envelope of the adjusted longitudinal noise torque signal 528 , Thereafter, the extracted envelope signals 562 . 564 multiplexed (eg by multiplexer module 368 ) and used to generate a gain and phase compensated motor drive control signal in a manner similar to that described above (e.g., steps 460 . 470 . 480 . 490 ) to create. In this way, the offset torque affects that of the envelope extraction modules 348 . 355 generated envelope signals, which in turn affect the subsequently generated, applied to the electric motor gain and phase-compensated motor drive control signal. As a result, the EPS motor applies torque that controls the vibrations transmitted to the steering wheel in the desired, from the control signal 530 displayed extent attenuates.

6 shows an exemplary embodiment of a SWV damping method 600 suitable for dynamically adjusting or otherwise controlling the amount of SWV damping / suppression provided by an EPS motor (eg motor 90 ). In exemplary embodiments, the SWV damping method is used 600 through the SWV suppression control module 280 in the steering system 200 from 2 performed, wherein the suppression control module 280 as the control module 500 from 5 is realized. The various tasks performed together with the illustrated method may be performed by hardware, suitably configured analog circuits, software executed by process circuits, firmware executable through process circuits, or any combination thereof. For purposes of illustration, the following description may be read in conjunction with the 1 - 5 refer to mentioned elements. In practice, parts of the SWV damping process 600 through different elements of the system 200 be performed, such as z. B. the suppression control module 280 , the control module 500 , the damping compensation arrangement 502 and / or the gain control module 540 , It should be clear that useful embodiments of the SWV damping method 600 may contain any number of additional or alternative activities, the activities need not be performed in the order presented and / or the activities may be performed concurrently and / or the SWV cushioning process 600 may be incorporated into a more comprehensive approach or method with additional functionality not described in detail herein. In addition, one or more could be in the context of 6 shown or described activities in a meaningful embodiment of the SWV damping method 600 be omitted as long as the intended overall functionality is maintained.

The illustrated method 600 begins by determining the magnitude of the disturbance torque at the angular frequency corresponding to the vehicle tires that is provided by the EPS torque sensor 602 has been measured, determining the size of the quenching component of the EPS motor 604 applied torque and determining an estimate of the gross (or total) disturbance torque within the steering system, based on the measured disturbance torque and the extinguishing torque at 606 , In this regard, as described above, the sizing block determines 508 the damping compensation arrangement 502 the size of the noise component of the torque sensor 92 . 350 at the angular frequency of the vehicle tires measured torque by calculating the size of the low-pass filtered transverse and measured longitudinal noise signals 341 . 346 by mixing the bandpass filtered torque signal 352 were determined. The second sizing block 510 the damping compensation arrangement 502 determines the size of the erase torque component by calculating the size of the extracted envelope signals 562 . 564 which were used to provide an earlier gain and phase compensated motor drive control signal recently provided to the EPS motor 291 to generate, which counteracts periodic disturbances in the steering system. After that, the summation block is calculated 512 the damping compensation arrangement 502 or otherwise determines the estimate of the gross drag torque within the steering system by adding the magnitude of the measured disturbance torque from the output of the sizing block 508 to the size of the EPS motor quenching torque from the output of the sizing block 510 ,

In exemplary embodiments, the SWV damping method proceeds 600 by identifying or otherwise determining a desired amount by the SWV suppression control module 608 and then calculating or otherwise determining an offset torque based on the desired SWV suppression and the total disturbance torque within the steering system 610 , As described above, the gain control module 540 the amount by which the SWVs are to be damped / suppressed to identify or otherwise determine a value between 0 (maximum damping / suppression) and 1 (minimum damping / suppression) and a control signal 530 provide that the identified level Suppression of the reinforcement module 514 which, in turn, is indicated by the gain module 514 applied gain factor. Depending on the embodiment, the gain control module 540 dynamically determine the desired amount of suppression based on any number of factors (or any combination thereof) such as, for example, For example, the desired energy consumption of the EPS motor, the desired longevity and / or life of the EPS motor, user preferences and / or default settings, real-time operating conditions determined by the vehicle (eg, current vehicle speed and / or acceleration and / or momentary vehicle speed Braking state of the vehicle or the like). In one embodiment, the gain control module is 540 with the brake ECU 273 which provides an indication of the current state of the brake system (or brakes) mechanically coupled to the vehicle tires, wherein the gain control module 540 the desired amount of suppression determined or otherwise determined based on the by the brake ECU 273 displayed real-time braking state. As described above, the gain module calculates 514 the offset torque by multiplying the estimated gross steering torque within the steering system at the output of the summation block 512 with the control signal 530 corresponding amplification factor.

Still in terms of 6 drives the SWV damping method 600 after determining the offset torque configured to provide the desired amount of SWV suppression / damping on the steering wheel, continue to determine the adjusted disturbance torque based on the offset torque 612 and generating a gain and phase compensated motor drive control signal based on the adjusted disturbance torque 614 , As described above, the damping compensation arrangement determines 502 adjusted mixed disturbance torque signals 526 . 528 by converting the calculated offset torque into lateral and longitudinal components 522 . 524 in the same coordinate quadrant as the extracted envelope signals 562 . 564 and subtracting the lateral and longitudinal offset torque signals 522 . 524 from the mixed lateral and longitudinal signals 341 . 346 , Thereafter, a gain and phase compensated motor drive control signal is generated based on the adjusted mixed disturbance torque signals 526 . 528 by generating extracted envelope signals 562 . 564 (eg step 440 ), Multiplexing the extracted envelope signals 562 . 564 in a multiplexed signal 369 and generating the gain and phase compensated motor drive control signal using the multiplexed signal 369 (eg steps 460 . 470 . 480 . 490 ). As described above, the gain and phase compensated motor drive control signal causes the EPS motor to adjust the engine torque which, when steered, assists the vehicle tires in a manner that dynamically reduces or otherwise counteracts periodic torque content at the angular frequency that corresponds to the vehicle tire and thereby provides the vehicle torque Steering wheel communicated dampens vibrations. The through the SWV damping method 600 The defined loop may repeat itself continuously in the operation of the EPS system to dynamically adjust the extent to which SWVs are suppressed / attenuated based on real-time operating conditions and / or other criteria.

Those skilled in the art will appreciate that the various illustrative logical blocks, circuits, and algorithmic steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. Some of the embodiments and implementations are described above in terms of functional and / or logical block components (or modules) and various method steps. It should be understood, however, that such block components (or modules) may be implemented in any number of hardware, software, and / or firmware components configured to perform the specified functions. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design requirements imposed on the overall system. Skilled artisans may implement the described functionality in a variety of ways for each particular application, but such implementation decisions should not be interpreted as inducing any departure from the scope of the present invention. For example, one embodiment of a system or component may include various integrated circuit components, e.g. For example, use memory elements, digital signal processor elements, logic elements, look-up tables, or the like that perform a variety of functions under the control of one or more microprocessors or other controllers. Additionally, those skilled in the art will appreciate that embodiments described herein are merely exemplary implementations.

The various illustrative logic blocks, modules and circuits described herein in connection with the disclosed embodiments may be practiced or carried out with a general purpose processor, a digital signal processor (DSP), an application specific circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, suitable for performing the functions described herein. A general purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computer devices, e.g. A combination of DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. The word "exemplary" is used exclusively herein to mean "serving as an example or illustration." Any embodiment described herein as "exemplary" is not necessarily to be interpreted as preferred or advantageous over other embodiments.

Process or algorithm steps described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module performed by a processor, or in a combination of the two. A software module may be embodied in a RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, a removable disk, a CD-ROM, or any other form of storage media known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be integrated in the processor. The processor and the storage medium may be housed in an ASIC. The ASIC may be located in a user station. Alternatively, the processor and the storage medium may be housed as discrete components in a user station.

In this document, such related terms as the first and second, and the like, may be used solely to distinguish one entity or action from another entity or action, without necessarily necessarily or immediately implied or implied by such structure a sequence between such entities or actions. Numeric ordinal numbers such as "first," "second," "third," etc., merely refer to distinct individuals of a plurality and do not imply any order or sequence unless specifically defined by the claims. The order of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order corresponding to such a sequence unless specifically defined by the claim form. The method steps may be interchanged in any order without departing from the scope of the invention, as long as such replacement is not contrary to the claims and is not logically nonsensical.

Furthermore, depending on the context, such words used in describing a relationship between different elements, such as "connect" or "coupled", do not imply that a direct physical relationship must be made between these elements. For example, two elements may be physically, electronically, logically or otherwise interconnected via one or more additional elements.

While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that there are a tremendous number of variations. It should also be understood that the exemplary embodiment or exemplary embodiments are merely examples that are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a suitable plan to implement the exemplary embodiment or exemplary embodiments. It should be understood that various changes in the function and arrangement of elements may be made without departing from the scope of the invention as set forth in the appended claims and their legal equivalents. Accordingly, details of the exemplary embodiments or other limitations described above should not be read into the claims in the absence of a clear indication to the contrary.

OTHER EMBODIMENTS

• A method of reducing vibration in a steering wheel caused by periodic disturbances in a steering system including the steering wheel and an electric motor configured to apply engine torque that facilitates steering by the steering wheel, the method comprising: determining a Gross torque, attributable to periodic disturbances in the steering system; Determining a desired amount of suppression of vibrations in the steering wheel; Determining an offset torque based on the gross torque and the desired amount of suppression; and Generating a motor control command signal in a manner that is influenced by the offset torque, wherein the engine control command signal affects the engine torque.
• 2. The method of embodiment 1, wherein the steering system includes at least one tire coupled to the steering wheel, wherein determining the gross torque includes determining a sum of a measured torque component at an angular frequency corresponding to the at least one tire and an erasing torque applied by the electric motor.
• 3. The method of embodiment 2, wherein determining the sum comprises: Determining the measured torque component as a first magnitude of a first complex coefficient defined by lateral and longitudinal components of a filtered torque signal at the angular frequency, the filtered torque signal being obtained from a sensor configured to measure torque in the steering system; Determining the cancellation torque as a second quantity of a second transversely and longitudinally extracted signals used to generate an earlier motor control command signal applied to the electric motor, complex coefficients defined; and Adage the first size and the second size to get the sum.
• 4. The method of embodiment 3, further comprising low-pass filtering the lateral and longitudinal components of the filtered torque signal prior to determining the first quantity.
• 5. The method of embodiment 2, wherein determining the offset torque includes multiplying the sum by a gain factor that corresponds to the desired amount of suppression.
• 6. The method of embodiment 1, further comprising: Transforming offset torque into lateral and longitudinal offset torque components; Determining an adjusted lateral torque component based on a difference between a mixed lateral component of a torque measured at an angular frequency of the steering system and the transverse offset torque component; Determining an adjusted longitudinal disturbance torque component based on a difference between a mixed longitudinal component of the angular frequency measured torque and the longitudinal offset torque component; Generating an extracted cross-envelope component based on the adjusted cross-over torque component, the extracted cross-envelope component corresponding to an amplitude envelope of the adjusted cross-over torque component; and Generating an extracted longitudinal envelope component based on the adjusted longitudinal disturbance torque component, the extracted longitudinal envelope component corresponding to an amplitude envelope of the adjusted longitudinal northeast torque component, wherein generating the engine control command signal includes generating the engine control command signal based on the extracted lateral and longitudinal envelope components.
• 7. The method of embodiment 6, wherein transforming the offset torque into lateral and longitudinal offset torque components generates the lateral and longitudinal offset torque components in a same coordinate quadrant as previously extracted lateral and longitudinal components.
• 8. Method according to embodiment 6, in which: Generating the extracted lateral and longitudinal envelope components contains: Applying one or more proportional, integral, and derivative gains to the adjusted cross-fault torque component to produce one or more first processed signals; and Filtering and summing the one or more first processed signals to produce a first extracted signal that is a weighted-combined version of one or more filtered proportional-scaled cross signal, a filtered integral-scaled cross signal, and a filtered derivative-scaled cross signal; and Generating the extracted longitudinal envelope component includes: Applying one or more proportional, integral, and derivative gains to the adjusted longitudinal perturbation torque component to produce one or more second processed signals; and Filtering and summing the one or more second processed signals to produce a second extracted signal that is a weighted-combined version of one or more filtered proportional-scaled longitudinal signal, a filtered integral-scaled longitudinal signal, and a filtered derivative-scaled longitudinal signal.
• 9. The method of embodiment 1, further comprising determining the desired amount of suppression based on real-time operating conditions determined by the vehicle including the steering system.
• 10. A vehicle, comprising: a steering wheel coupled to one or more tires to steer the one or more tires; and an electric motor coupled to the one or more tires for engine torque generating the steering of the one or more tires; and a control module coupled to the electric motor and configured to: determine a gross torque attributable to periodic disturbances in the vehicle; to determine a desired amount of suppression of the periodic disturbances in the steering wheel; determine an offset torque based on the gross torque and the desired amount of suppression; and generate a motor control command signal in a manner that is influenced by the offset torque, wherein the motor control command signal is applied to the electric motor to control the electric motor and to attenuate the periodic disturbances communicated to the steering wheel.
• 11. The vehicle of embodiment 10, further comprising a sensor to obtain a measured steering torque, the control module coupled to the sensor and configured to calculate the gross torque as a sum of a component of the measured steering torque of the one or more tires Angular frequency and a cancellation component of the engine torque to determine.
• 12. The vehicle according to embodiment 11, wherein the control module includes: a bandpass filter for filtering the measured steering torque and obtaining a filtered torque signal; a pair of mixers coupled to the bandpass filter for mixing the filtered torque signal with sinusoidal carrier signals at the angular frequency to obtain mixed lateral and longitudinal components of the filtered torque signal at the angular frequency; and a sizing block coupled to the pair of mixers for determining the component of the measured steering torque at the angular frequency as a first quantity of a first complex coefficient defined by the mixed lateral and longitudinal components of the filtered torque signal.
• 13. The vehicle according to embodiment 12, wherein the control module further includes: an offset dividing block for transforming offset torque into lateral and longitudinal offset torque components; a first extraction module for generating an extracted cross-envelope component based on a first difference between the cross component of the filtered mixed torque signal and the cross-offset torque component, the extracted cross-envelope component corresponding to an amplitude envelope of the first difference; and a second extraction module to generate an extracted longitudinal envelope component based on a second difference between the longitudinal component of the filtered mixed torque signal and the longitudinal offset torque component, the extracted longitudinal envelope component corresponding to an amplitude envelope of the second difference.
• 14. The vehicle according to embodiment 13, wherein the control module further includes: a second sizing block coupled to the first and second extraction modules to determine the erase component as a second size of a second complex coefficient defined by the extracted lateral and longitudinal envelope components; and an adjustable gain module configured to multiply the sum of the component of the measured mixed steering force at the angular frequency and the cancellation component by a gain factor to obtain the offset torque.
• 15. The vehicle of embodiment 14, wherein the offset dividing block is coupled to the tunable gain module, the first extraction module, and the second extraction module, wherein the offset dividing block is configured to: determine a transformation angle corresponding to the extracted lateral and longitudinal envelope components; and transform the offset torque into lateral and longitudinal offset torque components and divide the offset torque according to the transformation angle.
• 16. The vehicle of embodiment 15, wherein the offset dividing block is configured to: determine the transformation angle as the two coordinate parameters Arcustangent of the extracted lateral and longitudinal envelope components; and to divide the offset torque according to the transformation angle using: Multiplying the offset torque by a cosine of the transformation angle to obtain the longitudinal torque component; and Multiplying the offset torque by a sine of the transformation angle to obtain the lateral torque component.
• 17. The vehicle of embodiment 10, further comprising an electronic brake control unit coupled to the control module, wherein the control module is configured to determine the desired amount of suppression based on a real-time braking condition indicated by the electronic brake control unit.
• 18. A method for reducing vibrations in a steering wheel, caused by periodic disturbances in a steering system corresponding to one or more tires of a vehicle, in which the steering system includes the steering wheel and an electric motor coupled to the steering wheel and the one or more tires to apply engine torque to assist steering the one or more tires through the steering wheel, the method comprising: determining Transverse and longitudinal components of a measured disturbance torque at an angular frequency corresponding to the one or more tires; Determining a gross torque attributable to the periodic disturbances in the steering system based on the cancellation component and the lateral and longitudinal components of the measured disturbance torque at the angular frequency; Determining a gain factor corresponding to a desired amount of vibration suppression; Multiplying the gross torque by the gain factor to obtain an offset torque; Transforming offset torque into lateral and longitudinal offset torque components; Generating an extracted cross-envelope component based on a first difference between the transverse component of the measured disturbance torque at the angular frequency and the cross-offset torque component, wherein the extracted cross-envelope component corresponds to an amplitude envelope of the first difference; Generating an extracted longitudinal envelope component based on a second difference between the longitudinal component of the measured disturbance torque at the angular frequency and the longitudinal offset torque component, wherein the extracted longitudinal envelope component corresponds to an amplitude envelope of the second difference; and generating an engine control command signal based at least in part on the extracted lateral and longitudinal envelope components, the engine command signal affecting engine torque to dampen the vibrations transmitted to the steering wheel to the desired extent.
• 19. The method of embodiment 18, further comprising: Low pass filtering the transverse and longitudinal components of the measured disturbance torque at the angular frequency; and Determining a first magnitude of a first complex coefficient defined by the low-pass filtered lateral and longitudinal components of the measured disturbance torque at the angular frequency, wherein determining the gross torque includes adding the first magnitude to the cancellation component.
• 20. The method of embodiment 19, wherein the cancellation component includes determining a second magnitude of a second complex coefficient defined by the extracted lateral and longitudinal envelope components.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Shock and Vibration Handbook, 3rd Edition, Cyril M. Harris, page 2-15, McGraw-Hill Book Company, 1987 [0095]
• ISBN 0-07-026801-0. [0095]

Claims (10)

A method of reducing vibration in a steering wheel caused by periodic disturbances in a steering system including the steering wheel and an electric motor configured to apply engine torque that facilitates steering by the steering wheel, the method comprising: Determining a gross torque attributable to the periodic disturbances in the steering system; Determining a desired amount of suppression of vibrations in the steering wheel; Determining an offset torque based on the gross torque and the desired amount of suppression; and Generating a motor control command signal in a manner that is influenced by the offset torque, wherein the engine control command signal affects engine torque. The method of any preceding claim, wherein the steering system includes at least one tire coupled to the steering wheel, wherein determining the gross torque includes determining a sum of a measured torque component at an angular frequency corresponding to the at least one tire and an erasing torque applied by the electric motor. Method according to one of the preceding claims, wherein determining the sum comprises: Determining the measured torque component as a first magnitude of a first complex coefficient defined by lateral and longitudinal components of a filtered torque signal at the angular frequency, the filtered torque signal being obtained from a sensor configured to measure torque in the steering system; Determining the cancellation torque as a second quantity of a second transversely and longitudinally extracted signals used to generate an earlier motor control command signal applied to the electric motor, complex coefficients defined; and Adage the first size and the second size to get the sum. The method of any one of the preceding claims, further comprising low-pass filtering the lateral and longitudinal components of the filtered torque signal prior to determining the first quantity. The method of any one of the preceding claims, wherein determining the offset torque includes multiplying the sum by a gain corresponding to the desired amount of rejection. Method according to one of the preceding claims, further comprising: Transforming offset torque into lateral and longitudinal offset torque components; Determining an adjusted lateral torque component based on a difference between a mixed lateral component of a torque measured at an angular frequency of the steering system and the transverse offset torque component; Determining an adjusted longitudinal disturbance torque component based on a difference between a mixed longitudinal component of the angular frequency measured torque and the longitudinal offset torque component; Generating an extracted cross-envelope component based on the adjusted cross-over torque component, the extracted cross-envelope component corresponding to an amplitude envelope of the adjusted cross-over torque component; and Generating an extracted longitudinal envelope component based on the adjusted longitudinal disturbance torque component, the extracted longitudinal envelope component corresponding to an amplitude envelope of the adjusted longitudinal northeast torque component, wherein generating the engine control command signal includes generating the engine control command signal based on the extracted lateral and longitudinal envelope components. A vehicle containing: a steering wheel coupled to one or more tires to steer the one or more tires; and an electric motor coupled to the one or more tires to produce an engine torque that assists in steering the one or more tires; and a control module coupled to the electric motor and configured to: to determine a gross torque, attributable to periodic disturbances in the vehicle; to determine a desired amount of suppression of the periodic disturbances in the steering wheel; determine an offset torque based on the gross torque and the desired amount of suppression; and generate a motor control command signal in a manner that is influenced by the offset torque, wherein the motor control command signal is applied to the electric motor to control the electric motor and to attenuate the periodic disturbances communicated to the steering wheel. A vehicle according to claim 7, further comprising a sensor to measure a measured To obtain steering torque, wherein the control module is coupled to the sensor and configured to determine the gross torque as a sum of a component of the measured steering torque of an angular frequency corresponding to the one or more tires and a cancellation component of the engine torque. A vehicle according to claim 7 or 8, wherein the control module includes: a bandpass filter for filtering the measured steering torque and obtaining a filtered torque signal; a pair of mixers coupled to the bandpass filter for mixing the filtered torque signal with sinusoidal carrier signals at the angular frequency to obtain mixed lateral and longitudinal components of the filtered torque signal at the angular frequency; and a sizing block coupled to the pair of mixers for determining the component of the measured steering torque at the angular frequency as a first quantity of a first complex coefficient defined by the mixed lateral and longitudinal components of the filtered torque signal. The vehicle of any one of claims 7 to 9, further comprising an electronic brake control unit coupled to the control module, the control module configured to determine the desired amount of suppression based on a real-time braking condition indicated by the electronic brake control unit.

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