JP6791381B2 - Electric power steering device - Google Patents

Description

The present invention has a steering angle control mode (automatic steering control mode such as parking assistance) and an assist control mode (manual steering control mode) in steering control of a vehicle, and drives a motor according to a motor current command value. Regarding the electric power steering device that applies assist force to the steering system of the vehicle, in particular, the switching from the steering angle control mode to the assist control mode and the switching from the assist control mode to the steering angle control mode are gradually changed by the gradual change gain. At the same time, even in the rudder angle control mode, the manual input is judged without any erroneous judgment, the assist control mode is smoothly and surely shifted, and the unintended fluctuation of the steering wheel with respect to the motor current command value is suppressed. It relates to a high-performance electric power steering device that reduces discomfort to the driver.

An electric power steering device (EPS) that applies steering assist force (assist force) to the steering mechanism of a vehicle by the rotational force of the motor is a steering shaft that transmits the driving force of the motor via a speed reducer by a transmission mechanism such as a gear or a belt. Alternatively, a steering assist force is applied to the rack shaft. In such a conventional electric power steering device, feedback control of the motor current is performed in order to accurately generate the torque of the steering assist force. The feedback control adjusts the motor applied voltage so that the difference between the steering assist command value (current command value) and the motor current detection value becomes small, and the adjustment of the motor applied voltage is generally PWM (pulse width). Modulation) Control duty is adjusted.

The general configuration of the electric power steering device will be described with reference to FIG. 1. The column shaft (steering shaft, handle shaft) 2 of the handle (steering wheel) 1 has a reduction gear 3, universal joints 4a and 4b, and a pinion rack mechanism 5. , The tie rods 6a and 6b, and further connected to the steering wheels 8L and 8R via the hub units 7a and 7b. Further, the column shaft 2 is provided with a steering angle sensor 14 for detecting the steering angle θr of the steering wheel 1 and a torque sensor 10 for detecting the steering torque Th, and the motor 20 assisting the steering force of the steering wheel 1 is a reduction gear. It is connected to the column shaft 2 via 3. Electric power is supplied from the battery 13 to the control unit (ECU) 30 that controls the electric power steering device, and the ignition key signal IG is input via the ignition key 11. The control unit 30 calculates the current command value for assist control based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the motor 20 is controlled by the control command value Vref. Although the rudder angle θr is detected from the rudder angle sensor 14, it can also be obtained from a rotation sensor such as a resolver connected to the motor 20.

A CAN (Controller Area Network) 40 for exchanging various information on the vehicle is connected to the control unit 30, and the vehicle speed Vs can be received from the CAN 40. Further, a non-CAN 41 that transmits / receives communications other than CAN 40, analog / digital signals, radio waves, and the like can also be connected to the control unit 30.

The control unit 30 is mainly composed of a CPU (Central Processing Unit) (including an MPU (Micro Processor Unit) and an MCU (Micro Controller Unit)), and shows general functions executed by a program inside the CPU. It becomes as shown in FIG.

Explaining the function and operation of the control unit 30 with reference to FIG. 2, the steering torque Th detected by the torque sensor 10 and the vehicle speed Vs detected by the vehicle speed sensor 12 (or from CAN) set the current command value Iref1. It is input to the current command value calculation unit 31 to be calculated. The current command value calculation unit 31 calculates the current command value Iref1, which is the control target value of the current supplied to the motor 20, by using the assist map or the like based on the input steering torque Th and vehicle speed Vs. The current command value Iref1 is input to the current limiting unit 33 via the adding unit 32A, and the current command value Iref3 whose maximum current is limited by the overheat protection condition is input to the subtracting unit 32B and is fed back to the motor current value Im. The deviation Iref4 (= Iref3-Im) is calculated, and the deviation Iref4 is input to the PI control unit 35 for improving the characteristics of the steering operation. The voltage control command value Vref whose characteristics have been improved by the PI control unit 35 is input to the PWM control unit 36, and the motor 20 is PWM-driven via the inverter 37 as the drive unit. The current value Im of the motor 20 is detected by the motor current detector 38 and fed back to the subtraction unit 32B.

Further, a rotation sensor 21 such as a resolver is connected to the motor 20, and the actual steering angle θs is detected. The compensation signal CM from the compensation unit 34 is added to the addition unit 32A, and the system system is compensated by adding the compensation signal CM to improve the astringency, the inertial characteristics, and the like. The compensation unit 34 adds the self-aligning torque (SAT) 343 and the inertia 342 by the addition unit 344, further adds the convergence 341 to the addition result by the addition unit 345, and adds the addition result of the addition unit 345 to the compensation signal CM. It is said.

In recent years, vehicles having a steering angle control mode (parking assistance, etc.) and an assist control mode, and having a switching function between these control modes have appeared in such an electric power steering device, and when automatic steering is realized. , The steering angle control and the assist control are independently possessed, and the configuration in which these outputs are switched is common. Position speed control, which has excellent performance in terms of responsiveness and disturbance suppression, is used for steering angle control. Position control is composed of P (proportional) control, and speed control is composed of PI (proportional integration) control. ..

A general electric power steering device having a control function of a steering angle control mode and an assist control mode and having a function of switching a steering control mode will be described with reference to FIG. 3. The motor 150 is for detecting the motor rotation angle θs. A rotation sensor 151 such as a resolver is connected, and the motor 150 is driven and controlled via the vehicle side ECU 130 and the EPS side ECU 140. The vehicle-side ECU 130 has a switching command unit 131 that outputs a switching command SW of a steering angle control mode or an assist control mode based on a button, a switch, or the like indicating the driver's intention, and a signal such as a camera (image) or a laser radar. It is provided with a steering angle command value generation unit 132 that generates a steering angle command value θref that becomes a target steering angle θt based on the above. Further, the actual steering angle θr detected by the steering angle sensor 14 provided on the column shaft (steering shaft, steering wheel shaft) is input to the steering angle control unit 200 in the EPS side ECU 140 via the ECU 130.

The switching command unit 131 transmits a signal for identifying entering the steering angle control mode, for example, a signal indicating the driver's intention by a button or switch provided around the dashboard or steering wheel, or a vehicle state signal by a parking mode provided in the shift. Based on this, the switching command SW is output, and the switching command SW is input to the switching unit 142 in the EPS side ECU 140. Further, the steering angle command value generation unit 132 generates a steering angle command value θref by a known method based on data of a camera (image), a laser radar, etc., and uses the generated steering angle command value θref as a target steering angle θt. Is input to the steering angle control unit 200 in the EPS side ECU 140.

The EPS side ECU 140 is based on the assist control unit 141 that outputs the assist control command value Itref calculated based on the steering torque Th and the vehicle speed Vs, and the steering torque Th, the target steering angle θt, the actual steering angle θr, and the motor angular speed ωr. The steering angle control unit 200 that calculates and outputs the steering angle control command value Imref for steering angle control, and the switching unit 142 that switches between the assist control command value Itref and the steering angle control command value Imref by the switching command SW. The motor speed is obtained based on the current control / drive unit 143 that drives and controls the motor 150 based on the motor current command value Iref (= Itref or Imref) from the unit 142, and the motor rotation angle θs from the rotation sensor 151, and the motor. It is provided with a motor angular speed calculation unit 144 that calculates an actual steering angle speed (motor angular speed) ωr using the speed and the gear ratio. The motor angular velocity calculation unit 144 includes a low-pass filter (LPF) for cutting high-frequency noise after the calculation corresponding to the differentiation.

As shown in FIG. 4, the steering angle control unit 200 has a position control unit 210 that outputs a steering angular velocity command value ωc so that the actual steering angle θr follows the target steering angle θt, and the steering angular velocity command value ωc. It is composed of a speed control unit 220 that outputs a steering angle control command value Imref so as to follow ωr. Further, the switching unit 142 has an assist control mode (manual steering control) by the assist control unit 141 and a steering angle control mode (steering angle control mode) by the steering angle control unit 200 based on the switching command SW from the switching command unit 131 of the vehicle side ECU 130. (Position / speed control mode) is switched, and the assist control command value Itref is output in the assist control, and the rudder angle control command value Imref is output in the rudder angle control.

In an electric power steering device equipped with such a function, if the steering mode is suddenly switched by a switch or the like, the motor current command value Iref suddenly fluctuates and the steering wheel behavior becomes unnatural, which makes the driver feel uncomfortable. give.

Japanese Patent No. 391279 Japanese Patent No. 3845188 Japanese Unexamined Patent Publication No. 2004-17881 Japanese Unexamined Patent Publication No. 2012-11862 Japanese Unexamined Patent Publication No. 2004-35199

Therefore, a method of suppressing sudden fluctuations in the motor current command value is used by multiplying the steering angle control command value and the assist control command value by a gradual change gain and gradually switching the steering mode. However, in this method, the steering angle control command value is limited by the gradual gain and output to the motor current command value during switching, so the output is limited by the current command value with respect to the steering angle control command value. It gets smaller. Due to this limitation, the actual steering angular velocity of the motor becomes slower than the steering angular velocity command value, so that a deviation occurs between the steering angular velocity command value and the actual steering angular velocity, and the integrated value of I control in the speed control accumulates. Therefore, a larger steering angle control command value is output from the speed control. As a result, in a state where the gradual change gain gradually increases, the limitation due to the gradual change gain is relaxed, so that the steering angle control command value becomes an excessive value as the gradual change gain increases, and the steering wheel has a steering angular velocity. It responds excessively to the command value, giving the driver a sense of discomfort.

For example, Japanese Patent No. 391279 (Patent Document 1) proposes a method of controlling the steering angular velocity so as to gradually increase at the start of steering angle control to reduce discomfort to the driver due to sudden changes in the steering wheel at the start. .. However, in the method of Patent Document 1, when the gradual change starts, the value continues to increase until the upper limit is reached, so that there is a problem that the integrated value of the I control is excessively accumulated.

Further, in the conventional device, the driver operates the steering wheel during the steering angle control mode, and when it is determined that the steering torque exceeds a predetermined value set in advance, the steering angle control is stopped. However, if the judgment is made only by comparing the output of the torque sensor with a predetermined value, the steering wheel of the handle is controlled by the noise of the torque sensor, when the tire steps on a pebble, or when the steering angle is controlled by the motor. Due to the inertial torque, the output of the torque sensor may temporarily exceed a predetermined value, and there is a problem that the steering angle control is stopped each time. If the predetermined value is set higher to avoid such inconvenience, not only the steering angle control mode and the assist control mode interfere with each other to give the driver a sense of discomfort, but also the driver handles the steering wheel during steering angle control. There is a possibility that the steering angle control will not be stopped immediately even if you operate.

As an automatic steering device that solves such a problem, for example, Japanese Patent No. 3845188 (Patent Document 2) has been proposed. The device disclosed in Patent Document 2 detects a movement locus setting means for storing or calculating the movement locus of the vehicle to a target position, an actuator (motor) for steering the wheels, and a steering torque applied to the steering wheel by the driver. The drive of the actuator is controlled based on the steering torque detecting means (torque sensor) and the moving locus set by the moving locus setting means, and the steering torque of a predetermined value or more set in advance is detected for a predetermined time or more. In the automatic steering device of the vehicle provided with the actuator control means for stopping the control of the actuator based on the movement locus when the torque is increased, a plurality of predetermined values are set and the predetermined time is changed according to each predetermined value. It has become.

However, in the device disclosed in Patent Document 2, the steering angle control is stopped after a predetermined time corresponding to the steering torque of the driver has elapsed. There is a problem that it is complicated to set a plurality of types of predetermined values and change the predetermined time corresponding to each predetermined value, and the calculation load is large.

Further, Patent Document 3 shows that the scope of application of the conventional automatic steering technique is expanded to a low speed range, and operability, safety and comfort related to steering operation during driving are ensured, and an angle control method is used. It is disclosed that the steering torque threshold value is switched to the torque control method by the steering torque threshold value determining means after the steering is stopped according to the above. However, the switching condition in Patent Document 3 is when the value of the steering torque τ exceeds the constant τ0 (steering torque determination threshold) only N + 1 times in a row, the absolute value of the steering torque is taken, and the absolute value is the torque threshold. There is no mention or suggestion of superiority when comparing the points to be judged and the integrated value of the absolute value with the integrated threshold value.

Further, Patent Document 4 is an obstacle avoidance support device that determines that the assist steering force of the own vehicle is released when it is detected that the steering force of the driver exceeds the steering force that opposes the assist steering force. There is, Patent Document 4 discloses that the integrated value of the steering torque is calculated after the steering torque exceeds a predetermined reference threshold value. However, Patent Document 4 is an integral of the steering torque of the portion exceeding the reference threshold value, and does not relate to the absolute value of the steering torque. Further, Patent Document 5 relates to an automatic steering device that prevents the steering wheel from suddenly becoming lighter at the moment when the control state of the motor that steers the wheels is switched, and has two threshold values for a change in steering torque. Is set. However, the integral of Patent Document 5 relates to the vehicle speed and the yaw rate, and is different from the integral of the steering torque, and the second threshold value needs to be set in the dead zone region.

The present invention has been made in view of the above circumstances, and an object of the present invention is to gradually change the gain for switching from the steering angle control mode to the assist control mode and switching from the assist control mode to the steering angle control mode. In addition to gradually changing by using, by using the integration of the absolute value and the entire signal, the manual input is judged even in the steering angle control mode so that the assist control mode can be smoothly transitioned to the motor current command value. The purpose of the present invention is to provide a high-performance electric power steering device that suppresses unintended fluctuations in the steering wheel and reduces discomfort to the driver.

The present invention has a function of switching between the assist control mode and the rudder angle control mode by a switching command, and the first assist control command value calculated by the assist control unit and the first rudder calculated by the rudder angle control unit. Regarding an electric power steering device that generates a motor current command value with an angle control command value and drives a motor according to the motor current command value to assist and control the steering system of a vehicle, the above object of the present invention is steering torque and the above. Based on the switching command, the speed command gradual change gain and speed control gradual change gain used in the position speed control of the rudder angle control, and the rudder angle control output gradual change gain and the assist control output gradual change gain used when switching the control mode A switching determination / gradual change gain generation unit is provided, and the steering angle control unit inputs a steering angle command value as a target steering angle, and a steering angle speed command value based on the angle deviation between the target steering angle and the actual steering angle. The position control unit that outputs the rudder angle, the rudder angle speed command value is gradually changed according to the speed command gradual change gain, and the upper and lower limit values are limited and output. The rudder angle speed control unit that processes the target rudder angle speed to be processed based on the actual rudder angle speed and the speed gradual change gain, and the speed control current value output from the rudder angle speed control unit with the rudder angle control output gradual change gain. It is composed of a first gradually changing output unit that gradually changes and outputs a second steering angle control command value, and the first assist control command value output from the assist control unit is gradually changed to the assist control output. The motor current is provided with a second gradual change output unit that gradually changes with a gain and outputs a second assist control command value, and is based on the second rudder angle control command value and the second assist control command value. The switching determination / gradual change gain generation unit has a manual input determination unit that generates a command value, and the manual input determination unit has an LPF that filters the steering torque and an absolute value of the steering torque that has passed through the LPF. To the torque threshold, a torque value comparison unit that outputs as an output signal, an integration calculation unit that integrates the entire output signal and outputs the integrated output value, and the integrated output value from the integration calculation unit. It is achieved by being composed of a switching determination unit that outputs a steering torque determination signal by comparing with and the integration threshold.

According to the electric power steering device of the present invention, the steering angle control command value is gradually changed by the steering angle control output gradual change gain, the assist control command value is gradually changed by the assist control output gradual change gain, and the steering in the steering angle control. The angular speed command value and the rudder angle control current value are gradually changed by the speed command gradual change gain and the speed control gradual change gain, respectively, and the vibration damping signal that has undergone steering wheel vibration suppression processing is added to the steering angle control command value, so it is smooth. Mode switching is possible, unintended fluctuations in the steering wheel with respect to the motor current command value can be suppressed, and discomfort to the driver can be reduced.

Further, since the switching judgment / gradual gain generation unit that makes a manual input judgment based on the absolute value of the steering torque and generates the gradual change gain is provided, the integrated value of the integral control in the speed control is excessively accumulated. Without this, it is possible to suppress unintended fluctuations in the handle with respect to the motor current command value.

It is a block diagram which shows the outline of the electric power steering apparatus. It is a block diagram which shows the structural example of the control system of the electric power steering apparatus. It is a block diagram which shows an example of the electric power steering apparatus which has the switching function of the assist control mode and the steering angle control mode. It is a block diagram which shows the structural example of the rudder angle control part. It is a block block diagram which shows an example of the Embodiment of this invention. It is a block diagram which shows the structural example of the switching determination / gradual change gain generation part. It is a block diagram which shows the structural example of the manual input determination part. It is a block diagram which shows the structural example of the rudder angle control part, the preprocessing part and the switching part. It is a block diagram which shows the structural example of the rate limiter. It is a diagram which shows typically the operation example of the rate limiter. It is a block diagram which shows the detailed configuration example of a rudder angle control part. It is a characteristic figure which shows typically the characteristic example of the limiter in a rudder angle control part. It is a block diagram which shows the structural example of the steering wheel vibration damping part. It is a flowchart which shows the operation example of the switching determination / gradual change gain generation part. It is a time chart which shows typically the operation example of the gradual change gain used in this invention. It is a flowchart which shows the operation example of the manual input determination part. It is a time chart which shows typically the operation example of the manual input determination part. It is a flowchart which shows the operation example of the rudder angle control part. It is a block diagram which shows the other structural example of the preprocessing part. It is a block diagram which shows the other structural example of a position control part. It is a flowchart which shows the operation example by another structure of a preprocessing part and a position control part. It is a flowchart which shows the example of the whole operation of this invention. It is a flowchart which shows the detailed operation example of this invention. It is a time chart which shows the operation example of this invention schematically. It is a time chart which shows the operation example of this invention schematically. It is a time chart which schematically explains a problem in the case of making a manual input judgment only by an absolute value and a threshold value. It is a time chart which schematically explains the problem in the case of making a manual input judgment by integrating without using an absolute value. It is a time chart which schematically explains the effect when the absolute value and the threshold value are compared, and the effect when the manual input judgment is made by integration. It is a time chart which schematically explains the effect when the absolute value and the threshold value are compared, and the effect at the time of making a manual input judgment by integration. It is a figure which shows the example of the input waveform used for the verification of the LPF effect in a manual input determination part by simulation. It is a waveform diagram which shows the effect example (detection waveform) of LPF in a manual input determination part by simulation. It is a waveform diagram which shows the effect example (integral value) of LPF in a manual input determination part by simulation. It is a diagram which schematically explains the problem when the limiter is not used. It is a diagram which schematically explains the effect when the limiter is used.

In the present invention, the steering angle control command value is gradually changed by the steering angle control output gradual change gain, the assist control command value is gradually changed by the assist control output gradual change gain, and the steering angular velocity from the position control unit in the steering angle control unit. The command value is gradually changed by the speed command slow change gain, and the upper and lower limits of the rudder angular velocity command value after the slow change are input to the rudder angular velocity control unit by limiting the target steering angular velocity with a limiter according to the speed command slow change gain. .. The rudder angular velocity control unit further performs control calculations based on the target steering angular velocity and the actual rudder angular velocity, and gradually changes with the speed control gradual change gain to output the speed control current value, and the vibration suppression signal from the handle vibration suppression unit. Is added to the speed control current value to output the steering angle control command value.

Further, in the present invention, a switching determination / gradual gain generation unit for inputting the steering torque and the switching command is provided, and the switching determination / gradual gain generation unit is based on the steering torque and the switching command to obtain the speed command gradual gain and speed. The control gradual change gain, the rudder angle control output gradual change gain, and the assist control output gradual change gain are generated. The speed command gradual change gain and the speed control gradual change gain are used for position speed control in the steering angle control unit, and the steering angle control output gradual change gain and the assist control output gradual change gain are used when switching the control mode. In the generation of each of these gradual gains, a manual input determination unit that determines manual input based on the steering torque is used, and the manual input determination unit obtains the absolute value of the steering torque via the LPF and is not related to the steering direction. Integrate the entire absolute value, compare the absolute value with the torque threshold, start the integration calculation of the entire absolute value when the absolute value is equal to or greater than the torque threshold, compare the integrated value with the integration threshold, and compare the torque. The judgment signal is obtained. As a result, when the steering wheel steering is started during the steering angle control mode, it is possible to reliably and smoothly shift to the assist control mode without being affected by the disturbance torque (noise).

Further, in the present invention, the front stage (or inside the steering angle control unit) of the steering angle control unit is provided with a preprocessing unit that performs limit processing and rate limit processing on the steering angle command value and eliminates steering wheel vibration. Since the position and speed are controlled for the pre-processed target steering angle, it does not give a sense of discomfort even to sudden steering. Further, in the embodiment in which the steering wheel vibration removing unit and the feedforward (FF) filter are provided in the position control unit in the steering angle control unit, the steering angle control command value in which the steering wheel vibration (around 10 Hz) is suppressed can be generated.

The steering angle control command value from the steering angle control unit is gradually changed by multiplying the steering angle control output gradual change gain, and the assist control output gradual change gain is applied to the assist control command value from the assist control unit. The rudder angle control output gradual change gain and the assist control output gradual change gain are set to the opposite increase / decrease characteristics by multiplying by. That is, the steering angle control output gradual change gain and the assist control output gradual change gain are each ratio (the steering angle control output gradual change gain is 0.0 (0%) to 1.0 (100%) when the control mode is switched. The total value of the assist control output gradual change gain of 1.0 (100%) to 0.0 (%) is 1.0 in principle, that is, 100%, and the opposite relationship increases or decreases (linear or It has a characteristic of being non-linear). When the mode is switched, the steering angle control output gradual change gain and the assist control output gradual change gain increase or decrease in the opposite relationship, but in the steering angle control mode, the total value of both is 1.0 (100%). It does not have to be.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 5 shows a configuration example of the present invention corresponding to FIG. 3, and in the present invention, a steering torque Th and a switching command SW are newly input to make a switching determination, and for speed gradual change in steering angle control. Switching determination / gradual change gain generator 400 that outputs and manages the gradual change gain SG (SG1, SG2) and the gradual change gain SWG (SWG1, SWG2) for control mode switching gradual change, and the rudder in the vehicle side ECU 130. A pre-processing unit 500 that processes the steering angle command value θref from the angle command value generating unit 132 and outputs the target steering angle θt is provided. The gradual change gain SG (SG1, SG2) for speed gradual change is input to the steering angle control unit 200, and the gradual change gain SWG (SWG1, SWG2) for mode switching gradual change is input to the switching unit 142.

The switching determination / gradual change gain generation unit 400 has a configuration as shown in FIG. 6, for example, a manual input determination unit 410 that inputs steering torque Th and outputs a torque determination signal TD described later, and steering torque Th and torque determination. The speed command gradual change gain SG1 and the speed control gradual change gain SG2 are generated and output based on the signal TD and the switching command SW, and the gradual change gain generator 430, and the steering angle control based on the torque determination signal TD and the switching command SW. It is composed of an output gradual change gain SWG1 and a gradual change gain switching generation unit 420 that calculates and outputs an assist control output gradual change gain SWG2. The switching command SW indicates switching from the steering angle control mode to the assist control mode, or switching from the assist control mode to the steering angle control mode, and the torque determination signal TD indicates when the steering wheel is steered during the steering angle control mode. Instructs to switch to the assist control mode.

The manual input determination unit 410 has a configuration as shown in FIG. 7, and has an LPF (low pass filter) 411 for removing disturbance torque (noise) of the steering torque Th and an absolute steering torque Th output from the LPF 411. The absolute value unit 412 for obtaining the value | The | and the torque value comparison unit 413 for outputting the output signal Ct or the past value initialization signal Pi by comparing the absolute value | The | of the steering torque The with a predetermined torque threshold Tth. , The limiter 414 that limits the upper and lower limits of the output signal Ct so that an excessive signal is not input, the integration calculation unit 415 that integrates the entire integration input value Cta from the limiter 414, and the integration calculation unit 415. It is composed of a switching determination unit 416 that outputs a steering torque determination signal TD by comparing the integrated integrated output value Iout with a predetermined integration threshold Sth. The integral calculation unit 415 may be a pure integral or a pseudo-integral composed of a first-order LPF. The integration calculation unit 415 performs an integration calculation of the entire integration input value Cta from the limiter 414, that is, the integration input value Cta (= Cta-0) from the value 0 in chronological order, and the integration output from the integration calculation unit 415. By comparing the output value Iout with the integration threshold Sth, it is less likely to be affected by the disturbance torque.

When the tire collides with a curb or stone, the steering torque Th temporarily exceeds the predetermined value due to the inertial torque of the handle, or the steering torque Th is less than the predetermined value, the automatic steering control is switched. The LPF 411 that removes the disturbance torque (noise) of the steering torque Th is provided in order to prevent it from becoming loose or difficult to switch. The LPF411 may be primary or secondary or higher, and may be an IIR (Infinite Impulse Response) type or FIR (Finite Impulse Response) type filter that removes disturbance torque (noise) and may be mountable. The effect of LPF411 will be described later with specific examples.

The torque value comparison unit 413 compares the absolute value | The | of the steering torque The with the torque threshold value Tth, and when the absolute value | The | When the integration operation of the integration input value Cta is started and the integration is continued and the absolute value | The | becomes smaller than the torque threshold value Tth, the integration calculation unit 415 receives the past value initialization signal from the torque value comparison unit 413. The integrated value is initialized to 0 by Pi. That is, the torque value comparison unit 413 performs the following operations. Since the comparison is made using the absolute value | The | of the steering torque The, the determination can be made only by the size without considering the steering direction of the steering wheel.
(Number 1)
When | The | ≧ Tth, the output signal Ct = | The |
When | Th | <Tth, output signal Ct = 0, past value initialization signal Pi output

When the past value initialization signal Pi is output from the torque value comparison unit 413, the past value holding unit (Z ^-1 ) in the integration calculation unit 415 is initialized to 0. Further, the switching determination unit 416 compares the integrated output value Iout from the integral calculation unit 415 with the integral threshold value Sth, and when the integrated output value Iout is equal to or higher than the integral threshold value Sth, the switching condition is satisfied and the steering angle control mode is assisted. The control mode is switched, and when the integrated output value Iout is smaller than the integration threshold value Sth, the switching condition is not satisfied and the steering angle control mode is continued. That is, the switching determination unit 416 performs the following operations.
(Number 2)
When Iout ≥ Sth, the steering torque judgment signal TD that satisfies the switching condition
When Iout <Sth, the steering torque judgment signal TD for which the switching condition is not satisfied

The steering torque determination signal TD from the manual input determination unit 410 is input to the gradual change gain generation unit 430 together with the steering torque Th and the switching command SW, and the gradual change gain generation unit 430 receives the speed command gradual change gain SG1 and the speed control gradual change. Generate gain SG2. The speed command gradual change gain SG1 is mainly used to realize smooth switching when switching from assist control to rudder angle control, and is used with respect to the rudder angular velocity command value ωc output from the position control unit (210). Used for gradual change and setting upper and lower limits. Further, the speed control gradual change gain SG2 has an integration-related signal (for example, an integral-related signal) in the steering angular velocity control unit (220) in order to mitigate the influence of accumulation of the integrated value in the steering angular velocity control unit (220) at the time of switching. It is multiplied by the integrated output value (Iout) and used to achieve smooth switching.

Further, the steering torque determination signal TD is input to the gradual change gain switching generation unit 420 together with the switching command SW, and the gradual change gain switching generation unit 420 generates the steering angle control output gradual change gain SWG1 and the assist control output gradual change gain SWG2. , The steering angle control output gradual change gain SWG1 and the assist control output gradual change gain SWG2 are input to the switching unit 142. The steering angle control output gradual change gain SWG1 is gradually changed by being multiplied by the steering angle control command value (current command value) Imref output from the limiter 203 of the steering angle control unit 200, and the switching operation of assist control and steering angle control is performed. It is used to smoothly perform the above and to realize a sense of discomfort to the driver, safety, etc. The assist control output gradual change gain SWG2 is multiplied by the assist control command value (current command value) Itref output from the assist control unit 141 and gradually changed to facilitate the switching operation between the steering angle control and the assist control. It is used to realize steering intervention by the driver during autonomous driving.

On the other hand, a configuration example of the steering angle control unit 200, the switching unit 142, and the preprocessing unit 500 is shown in FIG. 8, in which the preprocessing unit 500 has a steering angle command value for automatic operation from the steering angle command value generating unit 132. With respect to θref, the limiter 510 that limits the upper and lower limit values to prevent abnormal values and excessive values due to communication errors and the like from being input to the steering angle control unit 200, and the steering angle command value θref1 from the limiter 510. In order to prevent the rudder angle control current command value as the rudder angle control output from suddenly fluctuating due to a sudden change, the rudder angle command value θref1 is included in the rate limiter 520 that performs rate limit processing and the rudder angle command value θref2 after the rate limit. It is composed of a handle vibration removing unit 530 for reducing the steering wheel vibration frequency component.

The rate limiter 520 also leads to improvement in safety for the driver, such as being caught in the steering wheel due to sudden steering behavior. Further, when switching from the assist control mode to the steering angle control mode, the past value of the rate limiter is initialized to the actual steering angle θr. As a result, the target steering angle θt output from the steering wheel vibration removing unit 530 at the time of switching and the actual steering angle θr are substantially the same, so that sudden changes in the steering angle control current command value are suppressed, and as a result, the steering wheel is suddenly changed. Fluctuations can be prevented.

The rate limiter 520 has a configuration as shown in FIG. 9, for example, the steering angle command value θref1 is additionally input to the subtraction unit 520-1, and the steering angle command value θt1 which is the subtraction result from the past value is set by the change amount. The change amount θt2 is set in the part 520-2. The change setting unit 520-2 sets the difference θt1 between the past value from the holding unit (Z ^-1 ) 520-4 and the input (θref1), and sets the change θt2 and the past value in the addition unit 520-3. The addition result is output as a new steering angle command value θref2. The change amount setting unit 520-2 is for preventing the change amount from exceeding the set upper limit and lower limit, and its characteristic is to obtain the difference from the input (rudder angle command value) θref1 for each calculation cycle T. If it is outside the range of the upper limit and the lower limit of the change amount setting unit 520-2, the output θref2 is changed stepwise as shown in FIG. 10 by repeatedly adding the difference to the past value, and finally. The output θref2 is matched with the steering angle command value θref1. If the difference from the input (rudder angle command value) θref1 is within the upper and lower limits of the change setting unit 520-2, the change θt2 = difference θt1 is output and added to the past value. As a result, the output θref2 and the input (rudder angle command value) θref1 match. As a result, even if the steering angle command value θreft changes suddenly, the suddenly changing steering angle command value θref2 can be smoothly changed to prevent a sudden current change, and the driver's anxiety about automatic driving. It plays a function of reducing the feeling.

The steering wheel vibration removing unit 530 in the subsequent stage of the rate limiter 520 reduces the vibration frequency component included in the steering torque Th by a low-pass filter (LPF), a notch filter, or phase delay compensation. From the steering wheel vibration removing unit 530, the target steering angle θt preprocessed as described above is output.

The target steering angle θt from the preprocessing unit 500 is additionally input to the subtracting unit 210-1 in the position control unit 210 of the steering angle control unit 200 whose detailed configuration is shown in FIG. The actual rudder angle θr is subtracted and input to the subtraction unit 210-1, and the target rudder angle θt and the angular deviation θe of the actual rudder angle θr are obtained by the subtraction unit 210-1, and the angular deviation θe is the proportional unit 210-2. Is proportionally processed (gain Kpp), and the rudder angular velocity command value ωc is output from the position control unit 210. The steering angular velocity command value ωc is input to the multiplication unit 201, is gradually changed by the speed command gradual change gain SG1 in the multiplication unit 201, and the gradually changed steering angular velocity command value ωca is set according to the speed command gradual change gain SG1. Is input to the limiter 202 to limit. As shown in FIG. 12, for example, the limiter 202 limits the positive and negative upper and lower limit values according to the speed command gradual change gain SG1. That is, as the speed command gradual change gain SG1 becomes smaller, the limit value of the limiter 202 is also limited to be smaller, and as the speed command gradual change gain SG1 becomes larger, the limit value of the limiter 202 is also greatly limited. The operation of the limiter 202 will be described later with an example.

The target steering angular velocity ωcb whose upper and lower limits are limited by the limiter 202 is input to the steering angular velocity control unit 220 together with the actual steering angular velocity ωr and the speed control gradual change gain SG2. As shown in detail in FIG. 11, the steering angular velocity control unit 220 integrates the subtracting unit 221 that subtracts the actual steering angular velocity ωr from the target steering angular velocity ωcb and the speed deviation Df that is the subtraction result of the subtracting unit 221 (Kvi / s). ), The proportional part 225 that compensates by proportionally processing (Kvp) the actual steering angular velocity ωr, and the proportional result of the steering angle control current value Ir1 to the proportional part 225, which is the integration result of the integrating part 222. The subtraction unit 223 that subtracts the steering angular velocity control current value Ir2 and the speed control current value Imref0 that is the subtraction result of the subtraction unit 223 are gradually changed by the speed control gradual change gain SG2, and the speed control current value Imref1 is output. It is composed of a part 224. The speed control current value Imref1 from the multiplication unit 224 is input to the addition unit 204, is added to the vibration damping signal (current value) Thd from the handle vibration damping unit 440, and is a steering angle control command which is the addition result. The upper and lower limit values of the value Imref2 are limited by the limiter 203 for preventing overoutput, and the steering angle control command value Imref is output.

The steering wheel vibration damping unit 440 is provided to suppress the steering torque Th based on the torsion bar of the column shaft to further improve the vibration damping effect of the steering wheel vibration during automatic steering. The configuration of the steering wheel vibration damping unit 440 is, for example, FIG. 13, which is composed of a gain unit 441 that gains (Kv) the steering torque Th and a phase compensation unit 442 that phase-compensates the steering torque Kv · Th from the gain unit 441. ing. The phase compensation unit 442 is composed of, for example, a first-order filter, and the vibration damping signal Thd is output in the direction of eliminating the twist of the torsion bar. In addition to the primary filter, it can be applied as long as it has a damping effect on the steering wheel.

As shown in FIG. 8, the switching unit 142 adds a multiplication unit 142-1 for multiplying the steering angle control command value Imref by the steering angle control output gradual change gain SWG1, and an assist control output gradual change gain SWG2 for the assist control command value Itref. Addition unit 142 that outputs the motor current command value Iref by adding the multiplication unit 142-2 to be multiplied, the steering angle control command value Imrefg from the multiplication unit 142-1, and the assist control command value Itrefg from the multiplication unit 142-2. It is composed of -3.

In such a configuration, first, an operation example of the switching determination / gradual gain generation unit 400 will be described with reference to the flowchart of FIG.

First, it is determined from the switching command unit 131 whether or not the switching command SW is input (step S1), and if the switching command SW is not input, the steering wheel is steered (left and right) by the driver in the steering angle control mode. Then, the steering torque Th is input to the manual input determination unit 410 (step S2), and the manual input determination unit 410 performs the manual input determination as described above in Equation 2 and later (step S10), and the result of the determination is If the torque determination signal TD for switching the control mode is not output (step S20), the switching determination / gradual change gain generator 400 determines the speed command gradual change gain SG1, the speed control gradual change gain SG2, and the rudder angle control output gradual change. The gain SWG1 and the assist control output gradual change gain SWG2 are generated and transitioned to the value of the rudder angle control mode (step S21), and the speed command gradual change gain SG1 and the speed control gradual change gain SG2 are input to the rudder angle control unit 200. (Step S22), the rudder angle control output gradual change gain SWG1 and the assist control output gradual change gain SWG2 are input to the switching unit 142 (step S25). As a result, the rudder angle control by the rudder angle control unit 200 is continued.

Further, when the switching command SW is input in step S1 or when the steering torque determination signal TD determines that the control mode is switched in step S20, the switching determination / gradual change gain generation unit 400 determines the speed command gradual. The variable gain SG1 and the speed control gradual gain SG2, the steering angle control output gradual gain SWG1 and the assist control output gradual gain SWG2 are generated and transitioned to the value of the assist control mode (step S24), and the speed command gradual gain SG1 The speed control gradual change gain SG2 is input to the steering angle control unit 200 (step S22), and the steering angle control output gradual change gain SWG1 and the assist control output gradual change gain SWG2 are input to the switching unit 142 (step S25). As a result, the assist control by the assist control unit 141 is performed.

Here, regarding each gradual change gain used in the present invention, about each gradual change gain after detection of manual input by the driver during the automatic driving state (a state in which both steering angle control and assist control are intervened). An embodiment of shifting to the assist control mode will be described with reference to FIG. FIG. 15 (A) shows the gradual change operation of the steering angle control output gradual change gain SWG1, the speed command gradual change gain SG1, and the speed control gradual change gain SG2, and FIG. 15 (B) shows the accelerating control output gradual change gain SWG2. It shows the gradual change operation of. Manual input determination is completed at time t _10, shows a state of transition from the steering angle control mode to the assist control mode is a state in which the switches are shifted to time t ₁₁ is finished to assist control mode. After the manual input determination, the gradual gains SG1, SG2 and SWG1 gradually decrease from 100% and transition to 0% as shown in FIG. 15 (A). In the present embodiment, the frequency is changed linearly, but in order to facilitate the switching operation, the transition may be made with an S-shaped curve such as a clothoid curve, or a first-order LPF (cutoff frequency 2 [Hz]). The value passed through may be used as each gradual change gain. However, the gradual change gains SG1, SG2, and SWG1 do not have to be interlocked with the same characteristics, and the assist control output gradual change gains SWG2 may be included and have independent characteristics. Further, the assist control output gradual change gain SWG2 does not always have to be 0% in the automatic operation state, and may be a value larger than 0%, for example, 50% as shown in FIG. 15 (B). By setting the assist control output gradual change gain SWG2 as an adjustment element to, for example, 50%, it is possible to suppress the feeling of being caught during steering intervention in the steering angle control mode. After the manual input determination, the transition from 50% to 100%.

Next, an operation example of the manual input determination unit 410 shown in FIG. 7 (step S10 in FIG. 14) will be described with reference to the flowchart of FIG.

When the steering torque Th is input (step S10-1), the disturbance torque (noise) is removed by the LPF411 (step S10-2), and the absolute value part 412 is the absolute value of the steering torque Tha from the LPF411 | The | (Step S10-3). The torque threshold value Tth is input to the torque value comparison unit 413 in advance, and the torque value comparison unit 413 determines whether or not the absolute value | The | is equal to or higher than the torque threshold value Tth (step S10-4), and the absolute value is determined. When | The | is equal to or more than the torque threshold value Tth, the output signal Ct is input to the integration calculation unit 415 as an absolute value | The |, and the integration operation is performed by the integration calculation unit 415 (step S10-5). When the absolute value | The | is smaller than the torque threshold value Tth, the output signal Ct is set to 0 so as not to integrate, and the past value initialization signal Pi is output to initialize the integration calculation unit 415. Set to 0 (step S10-6). Initialization is performed by resetting the past value holding unit (Z ^-1 ) in the integral calculation unit 415 to 0.

The integrated output value Iout from the integral calculation unit 415 is input to the switching determination unit 416, and the switching determination unit 416 determines whether or not the integrated output value Iout is equal to or higher than the integration threshold value Sth (step S10-7). When the integrated output value Iout is equal to or greater than the integrated threshold Sth, the switching condition of Equation 2 is satisfied (step S10-8), and the gradually changing gains SG1, SG2, SWG1, and SWG2 are updated by the steering torque determination signal TD (step S10-8). Step S10-9), the steering angle control mode is switched to the assist control mode (step S10-10). Further, when the integrated output value Iout is smaller than the integrated threshold value Sth, the switching condition of Equation 2 is not satisfied, and the control mode is not switched (step S10-11).

Figure 17 shows the context of the integration operation of an example of a temporal change with respect to the torque threshold value Tth of the disturbance torque steering torque Th removed (noise) (Tha) in LPF411, from the start to the time point _{t 1} is the steering torque Th Is smaller than the torque threshold Tth, so no integration is performed. From the time point t ₁ to the time point t ₂ , since the steering torque Th is equal to or higher than the torque threshold value Tth, the entire input signal is integrated, but since the total integrated value is smaller than the integration threshold value Sth, the switching condition is not satisfied. It has become. The integrated output value Iout corresponds to the area of the shaded area in FIG. 17, and is the total of the steering torque Th (absolute value). Then, from the time point t ₂ to the time point t ₃ , the steering torque Th is smaller than the torque threshold value Tth, so integration is not performed, and after the time point t _3, the steering torque Th is equal to or higher than the torque threshold value Tth, so integration is performed. Integrated value becomes a predetermined value (integration threshold Sth) above at time t _4, shows how the switching condition is satisfied. That is, although the area of the hatched portion in FIG. 17 has a integral value equivalent, the integral value at time t ₂ is switching condition smaller than the integral threshold value Sth is not satisfied, the integrated value at time t ₄ the integral threshold Sth or An example is shown in which the switching condition is satisfied.

Next, an operation example of the steering angle control unit 200 shown in FIGS. 8 and 11 will be described with reference to the flowchart of FIG. In this example, the steering angle command value θref is preprocessed by the preprocessing unit 500, and the preprocessed target steering angle θt is input to the steering angle control unit 200, but the preprocessing unit 500 is sent to the steering angle control unit 200. The configuration may include it.

The target steering angle θt, the actual steering angle θr, the actual steering angular velocity ωr, the steering torque Th, the speed command gradual change gain SG1 and the speed control gradual change gain SG2 are input (step S30), and the position is controlled by the position control unit 210 (step S30). Step S31). That is, the angle deviation θe between the target steering angle θt and the actual steering angle θr is obtained by the subtraction unit 211, and the angle deviation θe is proportionally processed by the proportional unit 212. The steering angular velocity command value ωc whose position is controlled by the position control unit 210 is gradually changed by the speed command gradual change gain SG1 in the multiplication unit 201 (step S32), and the gradually changed steering angular velocity command value ωca is a speed command in the limiter 202. Limit processing is performed according to the gradual change gain SG1 (step S33). The limit-processed target steering angular velocity ωcb is input to the subtracting section 221 in the steering angular velocity control unit 220, and the speed deviation Df from the actual steering angular velocity ωr is calculated (step S34). The velocity deviation Df is input to the integrating unit 222 and integrated (step S35), the actual steering angular velocity ωr is proportionally processed by the proportional unit 225 (step S36), and is proportionally processed from the integrated steering angle control current value Ir1. The steering angular control current value Ir2 is subtracted by the subtraction unit 223 (step S37), the speed control current value Imref0 obtained by the subtraction is input to the multiplication unit 224, and is gradually changed by the speed control gradual change gain SG2 (step). S40). The gradually changed speed control current value Imref1 is input to the addition unit 204.

Further, the steering torque Th is input to the handle vibration damping unit 440 and subjected to vibration damping processing (step S41), and the vibration damping signal Thd that has been vibration-damped is input to the addition unit 204 and added to the speed control current value Imref1. (Step S42). The added steering angle control command value Imref2 is limited to upper and lower limit values by the limiter 203 (step S43), and the steering angle control command value Imref2 is output (step S44).

The input order of the target rudder angle θt, the actual rudder angle θr, the actual rudder angular velocity ωr, the steering torque Th, the speed command gradual change gain SG1, and the speed control gradual change gain SG2 can be changed as appropriate.

In the above-described embodiment, the handle vibration removing unit 530 is provided in the pretreatment unit 500, but as shown in FIG. 19, the handle vibration removing unit 530 is removed as the pretreatment unit 500A, and the position control as shown in FIG. The configuration of the unit 200A may be used. That is, the pretreatment unit 500A is composed of a limiter 410 and a rate limiter 420, and the position control unit 200A includes a handle vibration removing unit 211, a subtracting unit 212, a feedforward (FF) filter 213, and a gain (Kpp) unit 214. It is composed of an addition unit 215 and an addition unit 215.

The target steering angle θt from the preprocessing unit 500A is input to the steering wheel vibration removing unit 211 and the FF filter 213 in the position control unit 210A. During automatic steering, when the rudder angle command is changing, a frequency (around 10 Hz) component that excites vibration due to the springiness of the torsion bar and the moment of inertia of the steering wheel is generated in the rudder angle command value θref. In order to reduce the steering wheel vibration frequency component included in the target steering angle θt, which is the steering angle command value after the preprocessing unit 500A (limiter 510, rate limiter 520) of the steering angle command value θref, the steering wheel vibration removing unit 211 It is provided. The handle vibration removing unit 211 reduces the vibration frequency component by LPF, a notch filter or phase delay compensation. The steering angle signal θt1 from the steering wheel vibration removing unit 211 is additionally input to the subtracting unit 212. Further, although the FF filter 213 is used to calculate the rudder angular velocity command value for improving the followability of the rudder angle control, a pseudo differential calculation and a gain unit may be combined and set in series. In this case, the LPF is placed after the differential operation in order to remove noise by the differential operation. Further, it may be based on a backward difference or an HPF (high-pass filter), and like the steering wheel vibration removing unit 211, a filter for reducing the frequency component (around 10 Hz) of the under vibration included in the target steering angle θt may be included. For example, a primary LPF (cutoff frequency 2 Hz), a notch filter (center frequency 10 Hz), a phase delay compensation filter, and the like are connected in series.

In such a configuration, an operation example of the preprocessing unit 500A and the position control unit 210A will be described with reference to the flowchart of FIG.

First, the steering angle command value θref is input (step S30-1), the preprocessing unit 500A is preprocessed by the limiter 510 and the rate limiter 520 (step S30-2), and the preprocessed target steering angle θt is output. (Step S30-3). The target steering angle θt is input to the steering wheel vibration removing unit 211 in the position control unit 210A, the steering wheel vibration frequency component of the target steering angle θt is removed by the steering wheel vibration removing unit 211 (step S31-1), and the steering wheel is handled by the subtracting unit 212. The angle deviation θe between the steering angle signal θt1 from the vibration removing unit 211 and the actual steering angle θt is obtained (step S31-2), and the angle deviation θe is proportionally processed (gain Kpp) by the proportional unit 214 (step S31-). 3). The proportionally processed angle deviation θeg is input to the addition unit 215. Further, the target rudder angle θt is input to the FF filter 213 and filtered (step S31-4), and the filtered angle signal θt2 is input to the addition unit 215 and added to the angle deviation θeg (step S31-5). , The added steering angular velocity command value ωc is output (step S31-6).

Although detailed operation examples of each part have been described above, the overall operation of the present invention will be described with reference to the configuration diagram of FIG. 5 and the flowchart of FIG. 22.

When the operation of the steering system is started, the assist control by the assist control unit 141 is executed (step S100), and the motor 150 is driven by the current control / drive unit 143 using the assist control command value Itref (step S101). The above operation is repeated until the switching command SW is output from the switching command unit 131 (step S102). The switching command SW is input to the switching determination / gradual gain generation unit 400 together with the steering torque Th.

When the steering angle control mode is set and the switching command SW is output from the switching command unit 131, the steering angle command value θref is input from the steering angle command value generation unit 132 to the preprocessing unit 500 (or 500A) (step S103). The target rudder angle θt preprocessed by the preprocessing unit 500 is input to the rudder angle control unit 200 (step S104), and the actual rudder angle θr from the rudder angle sensor 14 passes through the vehicle side ECU 130 to the rudder angle control unit 200. (Step S105), and the actual rudder angle speed ωr from the motor angle speed calculation unit 144 is input to the rudder angle control unit 200 (step S106). Further, the steering torque Th is input to the switching determination / gradual change gain generation unit 400 (step S107), and the switching determination / gradual change gain generation unit 400 uses the above-described method to perform the speed command gradual change gain SG1 and the speed control gradual change gain SG2. , The steering angle control output gradual change gain SWG1 and the assist control output gradual change gain SWG2 are generated (step S108), the speed command gradual change gain SG1 and the speed control gradual change gain SG2 are input to the steering angle control unit 200, and the steering angle is controlled. The control output gradual change gain SWG1 and the assist control output gradual change gain SWG2 are input to the switching unit 142. The steering angle control unit 200 generates a steering angle control command value Imref by the above-mentioned arithmetic processing (step S110), and the steering angle control command value Imref is input to the switching unit 142.

The assist control command value Itref from the assist control unit 141 and the rudder angle control command value Imref from the rudder angle control unit 200 are input to the switching unit 142, and the rudder angle control output gradually changing gain SWG1 and the assist control output. The gradual change gain SWG2 is input, and the gradual change is made in the above-mentioned relationship to switch from the assist control to the steering angle control (step S111). Then, the steering angle control is switched to, the steering angle control is performed (step S112), the manual input determination described above is performed (step S113), and the above operation is repeated until the integrated value reaches the integration threshold value Sth. (Step S114). When the integrated value reaches the integration threshold value Sth, the steering angle control is switched to the assist control by the gradual change by the steering angle control output gradual change gain SWG1 and the assist control output gradual change gain SWG2 (step S120).

A more detailed operation example of the above operation, particularly an operation example of the limiter 202 and the switching unit 142 will be described with reference to the flowchart of FIG. Here, the operations of the preprocessing unit 500 (or 500A) and the switching determination / gradual gain generation unit 400 are omitted because they overlap with the above description. In the example of FIG. 15, the assist control output gradual change gain SWG2 in the steering angle control state is described as 50%, but in FIG. 23, it is described as 0%.

First, the target rudder angle θt, the actual rudder angle θr, and the actual rudder angular velocity ωr are input (step S200), and then the speed command gradual change gain SG1, the speed control gradual change gain SG2, the steering angle control output gradual change gain SWG1, and the assist control output. The gradual gain SWG2 is input (step S201). The order of these inputs can be changed as appropriate. The position control unit 210 is position-controlled so as to follow the actual steering angle θr with the target steering angle θt, and the steering angular velocity command value ωc is output from the position control unit 210 (step S202). The steering angular velocity command value ωc is input to the multiplication unit 201, and the steering angular velocity command value ωca from the multiplication unit 201 is input to the limiter 202. The steering angular velocity command value ωca is input to the limiter 202, and the upper and lower limit values are limited by the limiter 202 as follows. That is, the speed command gradual change gain SG1 is input to the limiter 202, and the speed command gradual change gain SG1 is first added from the previous value (previous value at the first calculation = 0%) (step S203) (FIG. 24 described later). And when the velocity command gradual change gain SG1 is changed linearly with respect to the time series as shown in FIG. 25, the added value may be a constant value), and when the velocity command gradual change gain SG1 is 100% or more, it is 100%. (Steps S204, S205). It is determined whether or not the speed command gradual change gain SG1 is equal to or higher than the threshold value (step S206), and if the speed command gradual change gain SG1 is equal to or higher than the threshold value, the limiter limit value is added from the previous value (step S207). (When the speed command gradual change gain SG1 is linearly changed with respect to the time series as shown in FIGS. 24 and 25 described later, the added value may be a constant value.) Whether the limiter limit value is the limit value 2 or more. It is determined whether or not (step S208). When the limiter limit value is the limit value 2 or more, the limiter limit value is set to the limit value 2 (step S209).

After that, the multiplication unit 201 gradually changes with the speed command gradual change gain SG1 (step S210). The steering angular velocity command value ωca after the gradual change from the multiplication unit 201 is input to the limiter 202 to limit the upper and lower limit values (step S211). The target steering angular velocity ωcb from the limiter 202 is input to the steering angular velocity control unit 220 together with the actual steering angular velocity ωr, and speed control is performed to make the actual steering angular velocity ωr follow the target steering angular velocity ωcb.

The steering angle speed control unit 220 calculates the speed deviation Df, and also calculates the steering angle control current value Ir1 and the proportionally compensated steering angle control current value Ir2 as described above, and the speed control which is the deviation thereof. The current value Imref0 is calculated (step S212). The speed control current value Imref0 is gradually changed by the multiplication unit 224 by the speed control gradual change gain SG2, the gradually changed speed control current value Imref1 is output, and the speed control current value Imref1 is input to the addition unit 204 (step S213). ). Further, the vibration damping process based on the steering torque Th is performed, the vibration damping signal Thd after the vibration damping process is added to the speed control current value Imref1 by the addition unit 204, and the added steering angle control command value Imref2 is set by the limiter 203. Limit processing is performed, and the steering angle control command value Imref is output (step S214). The steering angle control command value Imref is gradually changed by the steering angle control output gradual change gain SWG1 in the multiplication unit 142-1 (step S215), and the gradually changed steering angle control command value Imrefg is input to the addition unit 142-3. ..

The assist control output gradual change gain SWG2 is input to the switching unit 142, and the assist control output gradual change gain SWG2 is subtracted from the previous value (previous value at the first calculation = 100%) (step S220), and the assist control output gradual change gain SWG2 is input. When the variable gain SWG2 is 0% or less, it is limited to 0% (steps S221 and S222). The assist control command value Itref is calculated, and the multiplication unit 142-2 gradually changes with the assist control output gradual change gain SWG2, and outputs the assist control command value Itrefg (step S223).

After that, the gradually changed assist control command value Itrefg is input to the addition unit 142-3, and is added to the steering angle control command value Imrefg to calculate the motor current command value Iref (step S224). The motor is driven by the motor current command value Iref. Then, the previous value of the steering angle control output gradual change gain SWG1 is updated to the steering angle control output gradual change gain SWG1, the previous value of the assist control output gradual change gain SWG2 is updated to the assist control output gradual change gain SWG2, and the speed is changed. The previous value of the commanded gradual change gain SG1 is updated to the speed command gradual change gain SG1, the previous value of the speed control gradual change gain SG2 is updated to the speed command gradual change gain SG2, and the previous value of the limiter limit value of the limiter 202 is changed. The limiter limit value is updated (step S225). Similarly, the previous values are updated for the speed command gradual change gain SG1 and the speed control gradual change gain SG2.

24 and 25 are time charts showing the relationship between the target steering angular velocity ωcc after the limiter 202, the steering angle control output gradual change gain SWG1, the assist control output gradual change gain SWG2, and the limiter 202 limit value 1 and limit value 2. is there. In the example of FIG. 15, the assist control output gradual change gain SWG2 in the steering angle control state is described as 50%, but in FIGS. 24 and 25, it is described as 0%. In the example of FIG. 24, the shift from the assist control to the steering angle control at the time point t0 is shown, and the steering angle control is completely performed at the time point t3. The limit value of the limiter 202 is from the limit value 1 to the limit value 2 (> limit value 1) between the time point t2 (set by the threshold value) slightly before the time point t3 when the steering angle is completely controlled and the time point t4 after the time point t3. ) Is gradually changing. The example of FIG. 25 also shows how the assist control is shifted to the steering angle control at the time point t10 and the steering angle control is completely performed at the time point t12. In this example, the limit value of the limiter 202 changes from the limit value 1 to the limit value 2 between the time point 12 when the steering angle is completely controlled and the time point t13 thereafter.

As shown at the time points t0 to t3 of FIGS. 24 (B) and 24 (C), and as shown at the time points t10 to t12 of FIGS. 25 (B) and (C), the steering angle control output gradually changing gain SWG1 and the assist The control output gradual change gain SWG2 increases or decreases in a relationship that the total value of the ratio is 1.0 (100%) in principle and vice versa. The increase / decrease waveform (characteristic) is arbitrary and may be linear or non-linear.

At the start of steering angle control (when switching from assist control), the speed command gradual change gain SG1 is multiplied by the steering angular velocity command value ωc of the output of the position control unit 210. This gradual change gain SG1 is synchronized with the gradual change gain SWG1 of the steering angle control output multiplied by the steering angle control command value Imref (it does not have to be completely synchronized). In addition, a limiter 202 having variable upper and lower limits is provided for the steering angular velocity command value ωca after multiplication of the speed command gradual change gain SG1. This limiter 202 can sequentially switch the limit value of the rudder angular velocity command value ωca, and this limit value is fixed at a small value when the gradual change gain SG1 is less than the set threshold value, and is gradually increased above the threshold value to obtain the rudder angular velocity command. The value ωca is limited and is input to the steering angular velocity control unit 220 as the target steering angular velocity ωcc. Further, the signal in the speed control unit 220 is multiplied by the speed control gradual change gain SG2 (which may be synchronized with SG1). As a result, the excessive accumulation of the integrated value in the steering angular velocity control unit 220 is suppressed, and the current command value as the steering angular velocity control output that causes a sense of discomfort to the driver is reduced. Further, after the gradual change is completed, the rudder angular velocity command value ωca is not limited by the speed command gradual change gain SG1 and the upper / lower limit variable limiter 202, and the signal in the rudder angular velocity control unit 220 is not limited by the speed control gradual change gain SG2. , Can be shifted to normal steering angle control. However, in the present embodiment, the speed control gradual change gain SG2 and the speed command gradual change gain SG1 are not displayed in FIGS. 24 and 25, and are matched with the steering angle control output gradual change gain SWG1. Further, in the first calculation at the time of switching to the steering angle control mode, the past value Z ^-1 of the rate limiter of the steering angle command value is overwritten with the detected actual steering angle. As a result, the target steering angle θt after the step of the steering wheel vibration removing unit 430 and the actual steering angle θr almost match at the time of switching, so that the generation of the steering angle control current command value is suppressed, and as a result, sudden fluctuation of the steering wheel is prevented. To do.

In the present invention, LPF411 (cutoff frequency 2 Hz in the primary filter) is used for the input unit of the manual input determination unit 410, and an absolute value unit 412 for obtaining the absolute value | The | of the steering torque Th is provided, and the steering torque Th The absolute value | The | is compared with the torque threshold Tth, and the integrated value is further compared with the integral threshold Sth, and the effects based on these factors will be described below.

FIG. 26 is schematically shown, and as shown in Patent Document 3, shows a problem when the manual input is determined only by the absolute value and the torque threshold value, and is transient while traveling on a rough road or the like. Due to the influence of a large road surface disturbance, a disturbance torque Td as shown in FIG. 26 (A) is generated around the column axis. Due to the influence of road surface disturbance (disturbance torque), the disturbance component gets on the steering torque (torsion bar torque), and as shown in Fig. 26 (B), if the torque threshold is exceeded even for a moment, the manual input is "Yes". There is a problem that it becomes a judgment. That is, it is a function that is easily affected by road surface disturbance and is easily erroneously determined.

Further, when the manual input is determined only by the torque threshold value and the integration threshold value as shown in Patent Document 4 without using the absolute value, the steering torque Th is positive or negative as shown in FIG. 27 (A). It is necessary to set the torque threshold value, and as shown in FIG. 27 (B), it is necessary to set the positive and negative integration threshold values with respect to the integrated output value Iout. As in the present invention, the absolute value | The | of the steering torque Th is obtained, the absolute value | The | is compared with the torque threshold Tth, and the integrated output value is further compared with the integral threshold Sth. As shown, even when the road surface disturbance occurs and the torque threshold value Tth is exceeded, the integrated output value Iout with respect to the torque does not reach the integrated threshold value Sth. That is, the present invention has an advantage that it is not easily affected by road surface disturbance and is unlikely to cause an erroneous determination.

FIG. 29 shows that the present invention is superior to the apparatus shown in Patent Document 4, and in the present invention, one torque threshold value Tth is set for the steering torque Th as shown in FIG. 29 (A). This is sufficient, and the branching process can be simplified as compared with the case where the absolute value is not converted. Further, since the input of the integration calculation unit 415 is an absolute value, even if the steering torque Th is negative (thin line), the integrated output value Iout is always 0 or more as shown in FIG. 29 (B), and the integration is performed. One integration threshold value Sth may be set for the output value Iout. There is an advantage that the branching process can be simplified as compared with the case where it is not converted to an absolute value. Since the absolute value conversion of the present invention is in the previous stage of the torque value comparison unit 413, the torque threshold value Tth and the integration threshold value Sth need to be one each.

As shown in FIG. 30 of the simulation, when the disturbance torque Td (torque conversion of the column shaft) is input to the steering torque Th when the steering angle command value is generated during the steering angle control, the torsion bar detection torque (steering). Torque Th) is shown by the thick line in FIG. 31 (simulation), and the steering torque Th after passing through LPF411 is attenuated in amplitude width as shown by the thin line in FIG. FIG. 31 also shows the torque threshold Tth used in the condition for executing the integration (integration) operation. Then, the result of integrating the signals corresponding to the presence / absence of LPF411 in FIG. 31 by the integration calculation unit 415 on the same time axis is shown in FIG. 29 of the simulation. The thin line in FIG. 32 is the integrated value of the steering torque Th (absolute value) without the LPF, and the thick line is the integrated value after the LPF (absolute value). In the integration calculation, the product of the calculation cycle 0.001 [s] and the steering torque Th (absolute value) is added to the previous value, and the integration threshold Sth is set to 3.5 [Nm]. The steering torque Th fluctuates due to the influence of the disturbance torque Td, and when the absolute value of the steering torque Th (Tha) falls below the torque threshold Tth, the integrated value is reset to 0 and a delay occurs before reaching the integrated threshold Sth. ing. As a result, the one with LPF411 inserted alleviates the influence of the disturbance torque Td, reaches the integration threshold value Sth earlier, and makes the manual input determination faster.

When the absolute value of the steering torque Th becomes an abnormal excessive value due to a temporary memory abnormality or the like, the integral input value Iout of the abnormal excessive value is integrated and the integrated output value Iout exceeds the integration threshold Sth. It may cause a false judgment. Therefore, in the present invention, by providing the limiter 414 before the integral input value Cta, even if the absolute value of the steering torque Th becomes an abnormally excessive value, the integral output value Iout does not exceed the integral threshold value Sth and is manually input. I try to prevent misjudgment. When there is no limiter, as shown in FIG. 33 schematically shown, when the absolute value | Tha | of the steering torque Th is smaller than the torque threshold value Tth, the integrated value is continuously reset to 0, so that the integrated output value Iout Is 0. As a matter of course, since the integral output value Iout is smaller than the integral threshold value Sth, it is determined that there is no manual input. However, when the absolute value | Th | of the steering torque Th becomes an abnormally excessive value as shown in FIG. 33 (A) due to a memory abnormality or the like, the torque threshold value Tth is exceeded and integrated with respect to the abnormally excessive value. Perform the calculation. Therefore, as shown in FIG. 33C, the integrated output value Iout exceeds the integration threshold value Sth, and the manual input “yes” is determined.

On the other hand, when there is a limiter, the torque threshold value is exceeded when the absolute value | The | of the steering torque Th | becomes an abnormally excessive value as shown in FIG. 34 schematically shown (FIG. 34 (A)). , Perform an integral operation on an abnormally excessive value. However, by limiting the integral input value Cta with the limiter 414 as shown in FIG. 34 (B), it is not necessary to perform the integral operation on the abnormally excessive value. Therefore, as shown in FIG. 34 (C), the integrated output value Iout does not become an excessive value, and it is possible to prevent erroneous determination of manual input.

Further, although the target is speed control in the above, it is also effective for a control method having a configuration in which inputs such as required rudder angles are accumulated and used for output such as current command values, and is effective for position control and speed control. If the above function is incorporated, other configurations can be changed as appropriate. Further, the actual steering angular velocity may be obtained from the motor speed and the reduction ratio, or may be obtained from the steering wheel steering angle sensor.

In the above description, the pre-processing unit and the steering angle control unit are separated, but the pre-processing unit may be included in the steering angle control unit. 10, FIG. 12, FIG. 15, FIG. 17, FIG. 24 to FIG. 29, FIG. 33, and FIG. 34 are all schematic views for easy understanding.

1 Handle (steering wheel)
2 Column shaft (steering shaft, steering wheel shaft)
10 Torque sensor 20, 150 Motor 30 Control unit (ECU)
31 Current command value calculation unit 130 Vehicle side ECU
140 EPS side ECU
141 Assist control unit 142 Switching unit 200 Steering angle control unit 202 Limiter 210, 210A Position control unit 220 Steering angular velocity control unit 400 Switching judgment / gradual change gain generation unit 410 Manual input judgment unit 420 Slow change gain switching generation unit 440 Handle vibration suppression Unit 500, 500A Pretreatment unit

Claims (5)

It has a function to switch between the assist control mode and the steering angle control mode by a switching command, and the first assist control command value calculated by the assist control unit and the first steering angle control command value calculated by the steering angle control unit. In an electric power steering device that generates a motor current command value and drives the motor according to the motor current command value to assist and control the steering system of the vehicle.
Based on the steering torque and the switching command, the speed command gradual change gain and the speed control gradual change gain used in the position speed control of the rudder angle control, and the steering angle control output gradual change gain and the assist control output gradual change used when switching the control mode. Equipped with a switching judgment / gradual gain generator that generates variable gain
The rudder angle control unit
A position control unit that inputs a rudder angle command value as a target rudder angle and outputs a rudder angle speed command value based on the angle deviation between the target rudder angle and the actual rudder angle, and the rudder angle speed command value is the speed command gradual change gain. A value determined based on a gradual change limiting unit that limits the upper and lower limit values and outputs a gradual change limiting unit, a target rudder angle speed output from the gradual change limiting unit, and an actual rudder angle speed. A rudder angle speed control unit that gradually changes according to the speed control gradual change gain and outputs a speed control current value, a handle vibration control unit that controls the steering torque, and a speed control unit that outputs the steering angle speed control unit. The addition unit that adds the vibration suppression signal output from the handle vibration suppression unit to the current value, and the added speed control current value output from the addition unit are gradually changed by the steering angle control output gradual change gain. The first gradual change output unit that outputs the second rudder angle control command value and the first assist control command value output from the assist control unit are gradually changed by the assist control output gradual change gain. It is equipped with a second gradual change output unit that outputs a second assist control command value.
The motor current command value is generated based on the second steering angle control command value and the second assist control command value.
The switching determination / gradual gain generation unit has a manual input determination unit.
The manual input determination unit compares the LPF that filters the steering torque with the absolute value of the steering torque that has passed through the LPF with the torque threshold value, and outputs the torque value comparison unit as an output signal, and the entire output signal. It is composed of an integration calculation unit that integrates and outputs the integration output value, and a switching determination unit that outputs a steering torque determination signal by comparing the integration output value from the integration calculation unit with the integration threshold.
The position control unit removes the handle vibration frequency component included in the target steering angle, the first steering angle signal from the handle vibration removing portion, and the first angle deviation of the actual steering angle. A subtraction unit for obtaining the first angle deviation, a proportional part for obtaining the second angle deviation by proportionally processing the first angle deviation, a feed forward (FF) filter for reducing the vibration component of the target rudder angle, and the second It includes an adder that adds the angle deviation and the second rudder angle signal from the FF filter and outputs the rudder angle speed command value.
An electric power steering device characterized by this. A pre-processing unit that converts the steering angle command value into the target steering angle is provided, and the pre-processing unit facilitates a limiter that limits the upper and lower limits of the steering angle command value and the output of the limiter. The electric power steering device according to claim 1, further comprising a rate limiter. The electric power steering device according to claim 1 or 2 , wherein the upper and lower limit values of the gradual change limiting unit are changed according to the speed command gradual change gain. The integrated output value starts integration when the steering torque converted to the absolute value reaches the torque threshold value in the steering angle control mode, and when the integrated output value reaches the integrated threshold value. The electric power steering device according to any one of claims 1 to 3 , wherein the steering angle control mode is switched to the assist control mode. The torque value comparison unit has a function of outputting a past value initialization signal that initializes the integration calculation unit when the steering angle control mode is in the steering angle control mode and the steering torque is smaller than the torque threshold value. The electric power steering device according to any one of claims 1 to 4 .

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