JP2021147018A - Vehicle steering device - Google Patents

Abstract

To provide a vehicle steering device that can ensure redundancy for steering angle.SOLUTION: When outputting an actual steering angle θr, a vehicle steering device outputs the actual steering angle θr as a steering angle θh, and when not outputting the actual steering angle θr, outputs an estimate θe, which is estimated on the basis of a motor angle θm, as a steering angle θh.SELECTED DRAWING: Figure 17

Description

The present invention relates to a vehicle steering device.

The electric power steering device (EPS), which is one of the steering devices for vehicles, applies an assist force (steering assist force) to the steering system of the vehicle by the rotational force of the motor. EPS applies the driving force of the motor controlled by the electric power supplied from the inverter to the steering shaft or the rack shaft as an assisting force by a transmission mechanism including a reduction mechanism. For example, a configuration is disclosed in which a target value of steering torque is set according to a steering angle, and a motor is driven and controlled so that the steering torque detected by the steering torque sensor becomes the target value of steering torque (for example). Patent Document 1).

Further, as a steering device for a vehicle, a steering reaction force generator (FFA: Force Feedback Accuator, steering mechanism) in which the driver steers, and a tire steering device (RWA: Road Wheel Actuator, steering mechanism) for steering the vehicle are steered. There is a steering device for vehicles of the Steer By Wire (SBW) type in which the mechanism) is mechanically separated. In such an SBW type vehicle steering device, the steering mechanism and the steering mechanism are electrically connected via a control unit (ECU: Electronic Control Unit), and an electric signal is used between the steering mechanism and the steering mechanism. Is generally controlled.

International Publication No. 2018/084190

By the way, in a vehicle system, high redundancy is required to realize a fail-safe function such as continuation of operation and safe stop in the event of an abnormality in each part. In the configuration where the target value of the steering torque is set according to the steering angle, if the sensor that acquires the steering angle fails and the steering angle (pulse signal according to the steering angle) is not output normally, it is based on the steering angle. You lose control. Further, in the SBW type vehicle steering device having a configuration in which the steering mechanism and the steering mechanism are controlled by an electric signal, the behavior may not be in line with the driver's intention.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle steering device capable of ensuring redundancy with respect to a steering angle.

In order to achieve the above object, the vehicle steering device according to one aspect of the present invention is for a vehicle that assists and controls the steering system of the vehicle via a reduction mechanism by driving and controlling a motor that assists the steering force. The steering device is a torsion bar provided on the column shaft of the vehicle, a first angle sensor that detects the actual steering angle, a second angle sensor that detects the motor angle, and an actual steering angle sensor. When the steering angle is output, the actual steering angle is output as the steering angle, and when the actual steering angle is not output from the first angle sensor, the motor angle output from the second angle sensor is used. A steering angle processing unit that outputs an estimated value estimated based on the steering angle, a target steering torque generating unit that generates a target steering torque when assist controlling the steering system based on the steering angle, and the target steering torque. Twist that calculates the current command value of the motor so that the twist angle of the torsion bar determined based on the difference between the steering angle and the motor angle is the target twist angle. It includes an angle control unit.

According to the above configuration, even if the first angle sensor that detects the actual steering angle fails, the estimated value estimated using the motor angle detected by the second angle sensor that detects the motor angle is controlled as the steering angle. Can be continued.

As a desirable embodiment of the vehicle steering device, the steering angle processing unit outputs the final value of the actual steering angle when the actual steering angle is output from the first angle sensor, and is output from the second angle sensor. When the final value of the motor angle and the final value of the twist angle of the torsion bar are held and the actual steering angle is no longer output from the first angle sensor, the torsion bar is compared with the final value of the actual steering angle. Multiply the difference between the final value of the torsion angle and the torsion angle of the torsion bar, the relative angle between the final value of the motor angle and the motor angle output from the second angle sensor, and the gear ratio of the reduction mechanism. It is preferable to calculate the estimated value by adding the value converted to the relative angle of the steering angle.

This makes it possible to calculate the estimated value using the motor angle.

As a desirable embodiment of the steering device for a vehicle, the steering angle processing unit is composed of an estimated steering angle calculation unit that calculates the estimated value, an actual steering angle output from the first angle sensor, and the estimated steering angle calculation unit. It is preferable to provide a switching unit that switches the output estimated value and outputs the target steering torque generation unit.

Thereby, the calculation process of the estimated value and the switching process between the actual steering angle and the estimated value can be separated.

As a desirable embodiment of the vehicle steering device, the estimated steering angle calculation unit calculates the estimated value when the actual steering angle is not output from the first angle sensor, and the switching unit uses the first switching unit. When the actual steering angle is output from the angle sensor, the actual steering angle is output as the steering angle to the target steering torque generating unit, and when the actual steering angle is not output from the first angle sensor, the above It is preferable to output the estimated value as the steering angle to the target steering torque generating unit.

As a result, since the estimated value is calculated when the actual steering angle is not output, it is possible to reduce the processing when the actual steering angle is output.

According to the present invention, it is possible to provide a steering device for a vehicle that can secure redundancy with respect to a steering angle.

FIG. 1 is a diagram showing a first example of a configuration in which a vehicle steering device is applied to an electric power steering device (EPS). FIG. 2 is a schematic view showing a hardware configuration of a control unit that controls an electric power steering device. FIG. 3 is a structural diagram showing an installation example of the rudder angle sensor. FIG. 4 is a diagram showing an example of the internal block configuration of the control unit of the first example shown in FIG. FIG. 5 is a diagram for explaining a method of determining the steering direction. FIG. 6 is a flowchart showing an operation example of the control unit of the first example shown in FIG. FIG. 7 is a block diagram showing a configuration example of the target steering torque generation unit. FIG. 8 is a diagram showing a characteristic example of the basic map held by the basic map unit. FIG. 9 is a diagram showing a characteristic example of the damper gain map held by the damper gain map unit. FIG. 10 is a diagram showing a characteristic example of the hysteresis correction unit. FIG. 11 is a block diagram showing a configuration example of the twist angle control unit. FIG. 12 is a diagram showing a second example of a configuration in which a vehicle steering device is applied to an SBW system. FIG. 13 is a diagram showing an example of the internal block configuration of the control unit of the second example shown in FIG. FIG. 14 is a diagram showing a configuration example of a target steering angle generation unit. FIG. 15 is a diagram showing a configuration example of the steering angle control unit. FIG. 16 is a flowchart showing an operation example of the control unit of the second example shown in FIG. FIG. 17 is a flowchart showing an example of a processing flow in the steering angle processing unit according to the first embodiment. FIG. 18 is a block diagram showing a configuration example of the steering angle processing unit according to the second embodiment. FIG. 19 is a flowchart showing an example of the calculation processing flow of the estimated steering angle in the estimated steering angle calculation unit of the steering angle processing unit according to the second embodiment. FIG. 20 is a flowchart showing an example of a switching processing flow between the actual steering angle and the estimated steering angle in the switching unit of the steering angle processing unit according to the second embodiment.

Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In addition, the components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, that is, those in a so-called equal range. Further, the components disclosed in the following embodiments can be appropriately combined.

(Composition of electric power steering)
FIG. 1 is a diagram showing a first example of a configuration in which a vehicle steering device is applied to an electric power steering device (EPS). The electric power steering device (EPS), which is one of the steering devices for vehicles, has a column shaft (steering shaft, steering shaft) 2 of the steering wheel 1, a reduction mechanism 3, and a universal joint in the order in which the force given by the steering wheel is transmitted. It is connected to the steering wheels 8L and 8R via the 4a and 4b, the pinion rack mechanism 5, the tie rods 6a and 6b, and further via the hub units 7a and 7b. Further, the column shaft 2 having the torsion bar is provided with a torque sensor 10 for detecting the steering torque Ts of the steering wheel 1 and a steering angle sensor 14 for detecting the actual steering angle θr to assist the steering force of the steering wheel 1. The motor 20 is connected to the column shaft 2 via the reduction mechanism 3. Power is supplied from the battery 13 to the control unit (ECU) 30 that controls the electric power steering device, and an ignition key signal is input via the ignition key 11. The control unit 30 calculates the current command value of the assist (steering assistance) command based on the steering torque Ts 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 voltage control command value Vref. The angle sensor 15 detects the motor angle θm of the motor 20.

An in-vehicle network such as a CAN (Controller Area Network) 40 that exchanges various vehicle information is connected to the control unit 30. Further, a non-CAN 41 that transmits / receives communications other than the 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 (including an MCU, an MPU, etc.). FIG. 2 is a schematic view showing a hardware configuration of a control unit that controls an electric power steering device.

The control computer 1100 constituting the control unit 30 includes a CPU (Central Processing Unit) 1001, a ROM (Read Only Memory) 1002, a RAM (Random Access Memory) 1003, an EEPROM (Electrically Erasable Programmable ROM) 1004, and an interface (I / F). ) 1005, A / D (Analog / Digital) converter 1006, PWM (Pulse Width Modulation) controller 1007, etc., which are connected to the bus.

The CPU 1001 is a processing device that controls the electric power steering device by executing a computer program for controlling the electric power steering device (hereinafter referred to as a control program).

The ROM 1002 stores a control program for controlling the electric power steering device. Further, the RAM 1003 is used as a work memory for operating the control program. The EEPROM 1004 stores control data and the like input and output by the control program. The control data is used on the control computer program expanded in the RAM 1003 after the power is turned on to the control unit 30, and is overwritten on the EEPROM 1004 at a predetermined timing.

The ROM 1002, RAM 1003, EEPROM 1004, and the like are storage devices for storing information, and are storage devices (primary storage devices) that can be directly accessed by the CPU 1001.

The A / D converter 1006 inputs signals such as the steering torque Ts, the current detection value Im of the motor 20, and the actual steering angle θr, and converts them into digital signals.

Interface 1005 is connected to CAN 40. The interface 1005 is for receiving a vehicle speed V signal (vehicle speed pulse) from the vehicle speed sensor 12.

The PWM controller 1007 outputs PWM control signals for each phase of UVW based on the current command value for the motor 20.

FIG. 3 is a structural diagram showing an installation example of the rudder angle sensor.

The column shaft 2 is provided with a torsion bar 2A. The road surface reaction force Rr and the road surface information μ act on the steering wheels 8L and 8R. A steering angle sensor 14 is provided on the handle 1 side of the column shaft 2 with the torsion bar 2A sandwiched therein, and an angle sensor 15 is provided on the steering wheel side (reduction mechanism 3 side shown in FIG. 1) of the column shaft 2. The steering angle sensor 14 detects the actual steering angle θr, and the angle sensor 15 detects the motor angle θm of the motor 20. Here, the actual steering angle θr detected by the steering angle sensor 14 will be referred to as the steering wheel angle θ _1, and the motor angle θ m detected by the angle sensor 15 will be referred to as the column angle θ ₂ . In the present disclosure, the steering angle sensor 14 corresponds to the first angle sensor. Further, in the present disclosure, the angle sensor 15 corresponds to the second angle sensor.

_{When a so-called increment method for detecting a relative angle is used as a sensor for detecting the handle angle θ 1} and the column angle θ ₂ in the present disclosure, the angle corresponding to the number of rotations of the handle 1 with respect to the detected value of the sensor. To determine the handle angle θ ₁ and the column angle θ _2. When a so-called absolute type sensor that detects the absolute angle of the motor rotation angle is used as the sensor that detects the handle angle θ ₁ and the column angle θ _{2 , the sensor detection values are the handle angle θ 1} and the column angle θ. _Let it be 2.

The twist angle Δθ of the torsion bar is expressed by the following equation (1) from the deviations _{of the handle angle θ 1} and the column angle θ _2. Further, the torsion bar torque Tt is expressed by the following equation (2) using the torsion angle Δθ of the torsion bar expressed by the equation (1). Kt is the spring constant of the torsion bar 2A.

Δθ = θ ₂ −θ ₁ ... (1)

Tt = −Kt × Δθ ... (2)

The torsion bar torque Tt can also be detected using a torque sensor. Here, the torsion bar torque Tt is also treated as the steering torque Ts.

FIG. 4 is a diagram showing an example of the internal block configuration of the control unit of the first example shown in FIG.

The control unit 30 includes a target steering torque generation unit 200, a twist angle control unit 300, a steering direction determination unit 400, a conversion unit 500, a steering angle processing unit 600, and the like as an internal block configuration. The rudder angle processing unit 600 will be described later.

The steering wheel steering of the driver is assist-controlled by the motor 20 of the EPS steering system / vehicle system 100. The EPS steering system / vehicle system 100 includes an angle sensor 15 and the like in addition to the motor 20.

In the present disclosure, the target steering torque generation unit 200 generates a target steering torque Tref, which is a target value of the steering torque when the steering system of the vehicle is assisted and controlled. The conversion unit 500 converts the target steering torque Tref into the target twist angle Δθref. The twist angle control unit 300 generates a motor current command value Imc, which is a control target value of the current supplied to the motor 20.

The twist angle control unit 300 calculates the motor current command value Imc so that the twist angle Δθ becomes the target twist angle Δθref. The motor 20 is driven by the motor current command value Imcc.

The steering direction determination unit 400 determines whether the steering direction is right-turning or left-turning based on the motor angular velocity ωm of the motor 20, and outputs the determination result as steering state signals STs. The motor angular velocity ωm is calculated by differentiating the motor angle θm detected by the angle sensor 15. FIG. 5 is a diagram for explaining a method of determining the steering direction.

The steering state indicating whether the steering direction is right-turning or left-turning can be obtained from the relationship between the steering angle θh and the motor angular velocity ωm as shown in FIG. 5, for example. That is, when the motor angular velocity ωm is a positive value, it is determined as “right turn”, and when it is a negative value, it is determined as “left turn”. Instead of the motor angular velocity ωm, an angular velocity calculated by performing a speed calculation on the steering angle θh or the motor angle θm may be used.

The conversion unit 500 converts the target steering torque Tref generated by the target steering torque generation unit 200 into the target twist angle Δθref using the relationship of the above equation (2).

Next, a basic operation example in the control unit will be described. FIG. 6 is a flowchart showing an operation example of the control unit of the first example shown in FIG.

The steering direction determination unit 400 determines whether the steering direction is right-turning or left-turning based on the code of the motor angular velocity ωm output from the EPS steering system / vehicle system 100, and uses the determination result as the steering state signal STs for target steering. Output to the torque generator 200.

The target steering torque generation unit 200 generates a target steering torque Tref at least based on the vehicle speed Vs, the steering state signal STs, and the steering angle θh (step S10).

The conversion unit 500 converts the target steering torque Tref generated by the target steering torque generation unit 200 into the target twist angle Δθref (step S20). The target twist angle Δθref is output to the twist angle control unit 300.

The twist angle control unit 300 calculates the motor current command value Imc based on the target twist angle Δθref, the steering angle θh, the twist angle Δθ, and the motor angular velocity ωm (step S30).

Then, current control is performed based on the motor current command value Imcc output from the twist angle control unit 300, and the motor 20 is driven (step S40).

FIG. 7 is a block diagram showing a configuration example of the target steering torque generation unit. As shown in FIG. 7, the target steering torque generation unit 200 includes a basic map unit 210, a multiplication unit 211, a code extraction unit 213, a differentiation unit 220, a damper gain map unit 230, a hysteresis correction unit 240, a multiplication unit 260, and addition. The parts 261,262 are provided. FIG. 8 is a diagram showing a characteristic example of the basic map held by the basic map unit. FIG. 9 is a diagram showing a characteristic example of the damper gain map held by the damper gain map unit.

The steering angle θh and the vehicle speed Vs are input to the basic map unit 210. The basic map unit 210 outputs a torque signal Tref_a0 with the vehicle speed Vs as a parameter, using the basic map shown in FIG. That is, the basic map unit 210 outputs the torque signal Tref_a0 according to the vehicle speed Vs.

As shown in FIG. 8, the torque signal Tref_a0 has a characteristic of increasing as the magnitude (absolute value) | θh | of the steering angle θh increases. Further, the torque signal Tref_a0 has a characteristic of increasing as the vehicle speed Vs increases. Although the map is configured by the magnitude | θh | of the steering angle θh in FIG. 8, the map may be configured according to the positive and negative steering angles θh. In this case, the value of the torque signal Tref_a0 can be a positive or negative value, and the code calculation described later becomes unnecessary. In the following description, a mode for outputting the torque signal Tref_a0, which is a positive value corresponding to the magnitude | θh | of the steering angle θh shown in FIG. 8, will be described.

Returning to FIG. 7, the code extraction unit 213 extracts the code of the steering angle θh. Specifically, for example, the value of the steering angle θh is divided by the absolute value of the steering angle θh. As a result, the code extraction unit 213 outputs "1" when the sign of the steering angle θh is "+", and outputs "-1" when the sign of the steering angle θh is "-". Specifically, the code extraction unit 213 generates, for example, a sign function (sign (θh)) of the steering angle θh.

The multiplication unit 211 multiplies the torque signal Tref_a0 output from the basic map unit 210 by "1" or "-1" output from the code extraction unit 213, and outputs the torque signal Tref_a to the addition unit 261. .. Specifically, the multiplication unit 211 multiplies the torque signal Tref_a0 output from the basic map unit 210 by the sign function (sign (θh)) of the steering angle θh generated by the code extraction unit 213, for example, to obtain the torque. It is output to the addition unit 261 as a signal Torf_a.

The steering angle θh is input to the differential unit 220. The differentiation unit 220 differentiates the steering angle θh to calculate the steering angular velocity ωh, which is the angular velocity information. The differential unit 220 outputs the calculated steering angular velocity ωh to the multiplication unit 260.

The vehicle speed Vs is input to the damper gain map unit 230. Damper gain map 230, using the damper gain map of vehicle speed sensitive type shown in FIG. 9, and outputs the damper gain D _G corresponding to the vehicle speed Vs.

As shown in FIG. 9, damper gain D _G has gradually increases as the vehicle speed Vs is high. Damper gain D _G may be a mode for varying according to the steering angle [theta] h.

Multiplying unit 260, with respect to the steering angular velocity ωh outputted from the differentiating unit 220, multiplies the damper gain _{D G} outputted from the damper gain map 230, and outputs the result to adding section 262 as a torque signal Tref_b.

The steering angle θh, the vehicle speed Vs, and the steering state signal STs, which are the determination results shown in FIG. 5, are input to the hysteresis correction unit 240. The hysteresis correction unit 240 calculates the torque signal Tref_c using the following equations (3) and (4) based on the steering angle θh and the steering state signal STs. In the following equations (3) and (4), x is the steering angle θh, y _R = Tref_c and y _L = Tref_c are torque signals (fourth torque signal) Tref_c. Further, the coefficient a is a value larger than 1, and the coefficient c is a value larger than 0. The coefficient Ahys indicates the output width of the hysteresis characteristic, and the coefficient c is a coefficient representing the roundness of the hysteresis characteristic.

y _R = Ahys {1-a- ^{c (x-b)} } ... (3)

y _L = -Ahys {1-a ^{c (x-b')} } ... (4)

When steering to the right, the torque signal (fourth torque signal) Tref_c (y _R ) is calculated using the above equation (3). At the time of left-turn steering, the torque signal (fourth torque signal) Tref_c (y _L ) is calculated using the above equation (4). When switching from right-turn steering to left-turn steering, or when switching from left-turn steering to right-turn steering, the final coordinates (x ₁ , y ₁ ) of the steering angle θh and the previous values of the torque signal Tref_c. Based on the value of, the coefficient b or b'shown in the following equation (5) or (6) is substituted for the above equations (3) and (4) after the steering is switched. As a result, continuity before and after steering switching is maintained.

b = x ₁ + (1 / c) log _a {1- (y ₁ / Ahys)} ... (5)

b'= x ₁ − (1 / c) log _a {1- (y ₁ / Ahys)} ... (6)

The above equations (5) and (6) can be derived by substituting _{x 1} for x and y _{1 for y R} and y _L in the above equations (3) and (4). ..

When, for example, the Napier number e is used as the coefficient a, the above equations (3), (4), (5), and (6) are the following equations (7), (8), and (9), respectively. ) And (10).

y _R = Ahys [1-exp {-c (x-b)}] ... (7)

y _L = -Ahys [{1-exp {c (x-b')}] ... (8)

b = x ₁ + (1 / c) log _e {1- (y ₁ / Ahys)} ... (9)

b'= x ₁ − (1 / c) log _e {1- (y ₁ / Ahys)} ... (10)

FIG. 10 is a diagram showing a characteristic example of the hysteresis correction unit. In the example shown in FIG. 10, in the above equations (9) and (10), Ahys = 1 [Nm] and c = 0.3 are set, starting from 0 [deg], and +50 [deg], -50. An example of the characteristics of the torque signal Tref_c with hysteresis correction when the steering of [deg] is performed is shown. As shown in FIG. 10, the torque signal Tref_c output from the hysteresis correction unit 240 has a hysteresis characteristic such as the origin of 0 → L1 (thin line) → L2 (broken line) → L3 (thick line).

Ahys, which is a coefficient representing the output width of the hysteresis characteristic, and c, which is a coefficient representing roundness, may be made variable according to one or both of the vehicle speed Vs and the steering angle θh.

Further, the rudder angular velocity ωh is obtained by a differential calculation with respect to the steering angle θh, but a low-pass filter (LPF) processing is appropriately performed in order to reduce the influence of high-frequency noise. Further, the differential operation and the LPF processing may be performed by the high-pass filter (HPF) and the gain. The motor angular velocity ωm may be used as the angular velocity information instead of the steering angular velocity ωh, and in this case, the differential unit 220 becomes unnecessary.

The torque signals Tref_a, Tref_b, and Tref_c obtained as described above are added by the addition units 261,262 and output as the target steering torque Tref.

In the twist angle control, the twist angle Δθ is controlled so as to follow the target twist angle Δθref calculated through the target steering torque generation unit 200 and the conversion unit 500 using the steering angle θh and the like. The motor angle θm of the motor 20 is detected by the angle sensor 15. Hereinafter, the twist angle control unit 300 (see FIG. 4) will be described with reference to FIG.

FIG. 11 is a block diagram showing a configuration example of the twist angle control unit. The twist angle control unit 300 calculates the motor current command value Imc based on the target twist angle Δθref, the twist angle Δθ, and the motor angular velocity ωm. The torsion angle control unit 300 includes a torsion angle feedback (FB) compensation unit 310, a torsion angular velocity calculation unit 320, a speed control unit 330, an output limiting unit 350, and a subtraction unit 361.

The target twist angle Δθref output from the conversion unit 500 is additionally input to the subtraction unit 361. The twist angle Δθ is subtracted and input to the subtraction unit 361 and input to the torsion angular velocity calculation unit 320.

The twist angle FB compensation unit 310 multiplies the compensation value CFB (transfer function) by the deviation Δθ0 of the target twist angle Δθref and the twist angle Δθ calculated by the subtraction unit 361, and the twist angle Δθ follows the target twist angle Δθref. The target torsional velocity ωref is output. The compensation value CFB may be a simple gain Kpp or a commonly used compensation value such as a PI-controlled compensation value.

The target torsional angular velocity ωref is input to the speed control unit 330. The twist angle FB compensation unit 310 and the speed control unit 330 make it possible to make the twist angle Δθ follow the target twist angle Δθref and realize a desired steering torque.

The torsion angular velocity calculation unit 320 performs differential calculation processing on the torsion angle Δθ to calculate the torsion angular velocity ωt. The torsion angular velocity ωt is output to the speed control unit 330. The torsion angular velocity calculation unit 320 may perform pseudo-differentiation by HPF and gain as a differential calculation. Further, the torsion angular velocity calculation unit 320 may calculate the torsion angular velocity ωt from another means or other than the torsion angle Δθ and output it to the speed control unit 330.

The speed control unit 330 calculates the motor current command value Imca so that the torsion angular velocity ωt follows the target torsional velocity ωref by IP control (proportional leading PI control).

The subtraction unit 333 calculates the difference (ωref−ωt) between the target torsional velocity ωref and the torsional angular velocity ωt. The integration unit 331 integrates the difference (ωref−ωt) between the target torsional velocity ωref and the torsional angular velocity ωt, and adds and inputs the integration result to the subtraction unit 334.

The torsion angular velocity ωt is also output to the proportional portion 332. The proportional unit 332 performs proportional processing with a gain Kvp on the torsion angular velocity ωt, and subtracts and inputs the proportional processing result to the subtraction unit 334. The subtraction result in the subtraction unit 334 is output as the motor current command value Imca. The speed control unit 330 is not an IP control, but a PI control, a P (proportional) control, a PID (proportional integral differential) control, a PI-D control (differential leading PID control), a model matching control, and a model norm. The motor current command value Imca may be calculated by a commonly used control method such as control.

The output limiting unit 350 has preset upper and lower limit values with respect to the motor current command value Imca. The output limiting unit 350 limits the upper and lower limits of the motor current command value Imca and outputs the motor current command value Imca.

The configuration of the twist angle control unit 300 shown in FIG. 11 is an example, and may be different from the configuration shown in FIG.

In the first example shown in FIG. 1, the vehicle steering device according to the first embodiment is applied to the column assist type EPS, but the system to which the vehicle steering device according to the first embodiment is applied is the column assist type EPS. It is applicable not only to the upstream assist type EPS represented by the above, but also to the so-called downstream type EPS represented by the dual pinion type EPS. Further, by performing feedback control based on the target twist angle, it can be applied to a steering bar (arbitrary spring constant) and a steering by wire (SBW) reaction force device having at least a sensor for detecting the twist angle. Hereinafter, an SBW system provided with a torsion bar to which the vehicle steering device according to the first embodiment can be applied will be described.

(SBW system)
FIG. 12 is a diagram showing a second example of a configuration in which a vehicle steering device is applied to an SBW system. The same components as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

The SBW system does not have an intermediate shaft that is mechanically coupled to the column shaft 2 at the universal joint 4a in the first example shown in FIG. 1, and consists of steering wheels 8L, 8R, etc. for operating the handle 1 by an electric signal. It is a system that conveys to the steering mechanism. As shown in FIG. 12, the SBW system includes a reaction force device 60 and a drive device 70, and a control unit (ECU) 50 controls both devices. The reaction force device 60 detects the steering angle θh by the steering angle sensor 14, and at the same time, transmits the motion state of the vehicle transmitted from the steering wheels 8L and 8R to the driver as a reaction force torque. The reaction force torque is generated by the reaction force motor 61. Although some SBW systems do not have a torsion bar in the reaction force device, the SBW system to which the present disclosure applies is a type that has a torsion bar, and the torque sensor 10 detects the steering torque Ts. do. Further, the angle sensor (second angle sensor) 74 detects the motor angle θm of the reaction force motor 61. The drive device 70 drives the drive motor 71 in accordance with the steering of the steering wheel 1 by the driver, applies the driving force to the pinion rack mechanism 5 via the gear 72, and operates the pinion rack mechanism 5 via the tie rods 6a and 6b. Steer the facing wheels 8L and 8R. An angle sensor 73 is arranged in the vicinity of the pinion rack mechanism 5, and detects the steering angle θt of the steering wheels 8L and 8R. In order to coordinately control the reaction force device 60 and the drive device 70, the ECU 50 adds information such as the steering angle θh and the steering angle θt output from both devices, and based on the vehicle speed Vs from the vehicle speed sensor 12 and the like. The voltage control command value Vref1 that drives and controls the reaction force motor 61 and the voltage control command value Vref2 that drives and controls the drive motor 71 are generated.

FIG. 13 is a diagram showing an example of the internal block configuration of the control unit of the second example shown in FIG. The configuration of the target steering torque generation unit 200a and the torsion angle control unit 300a is the same as the configuration of the target steering torque generation unit 200 and the torsion angle control unit 300 of the first example described above, and thus will be described in detail here. Is omitted.

In the second example shown in FIG. 12, the reaction force is controlled by controlling the twist angle Δθ (hereinafter referred to as “twist angle control”) and controlling the steering angle θt (hereinafter referred to as “turning angle control”). The device is controlled by twist angle control, and the drive device is controlled by steering angle control. The drive device may be controlled by another control method.

In the twist angle control, the twist angle Δθ follows the target twist angle Δθref calculated through the target steering torque generating unit 200a and the conversion unit 500 using the steering angle θh and the like by the same configuration and operation as in the first example. Such control is performed. The motor angle θm is detected by the angle sensor (second angle sensor) 74, and the motor angular velocity ωm is calculated by differentiating the motor angle θm by the angular velocity calculation unit 951. The steering angle θt is detected by the angle sensor 73. Further, although the processing in the EPS steering system / vehicle system 100 is not described in detail in the first example, the current control unit 130 includes the subtraction unit 32B, the PI control unit 35, and the PWM control unit shown in FIG. With the same configuration and operation as the 36 and the inverter 37, the reaction is based on the motor current command value Imc output from the torsion angle control unit 300a and the current value Imr of the reaction force motor 61 detected by the motor current detector 140. The force motor 61 is driven to control the current.

In the steering angle control, the target steering angle generation unit 910 generates a target steering angle θtref based on the steering angle θh, and the target steering angle θtref is input to the steering angle control unit 920 together with the steering angle θt. , The steering angle control unit 920 calculates the motor current command value Imct so that the steering angle θt becomes the target steering angle θtref. Then, based on the motor current command value Imct and the current value Imd of the drive motor 71 detected by the motor current detector 940, the current control unit 930 has the same configuration and operation as the current control unit 130, and the drive motor has the same configuration and operation. The 71 is driven to control the current.

FIG. 14 is a diagram showing a configuration example of the target steering angle generation unit. The target steering angle generation unit 910 includes a limiting unit 931, a rate limiting unit 932, and a correction unit 933.

The limiting unit 931 limits the upper and lower limits of the steering angle θh and outputs the steering angle θh1. Similar to the output limiting unit 350 in the twist angle control unit 300 shown in FIG. 11, the upper limit value and the lower limit value with respect to the steering angle θh are set in advance to limit the steering angle.

The rate limiting unit 932 sets and limits the amount of change in the steering angle θh1 in order to avoid a sudden change in the steering angle, and outputs the steering angle θh2. For example, the difference from the steering angle θh1 one sample before is used as the change amount, and when the absolute value of the change amount is larger than a predetermined value (limit value), the steering angle is set so that the absolute value of the change amount becomes the limit value. θh1 is added or subtracted and output as the steering angle θh2, and if it is equal to or less than the limit value, the steering angle θh1 is output as it is as the steering angle θh2. Instead of setting a limit value for the absolute value of the amount of change, an upper limit value and a lower limit value may be set for the amount of change to limit the amount of change. You may want to limit the rate.

The correction unit 933 corrects the steering angle θh2 and outputs the target steering angle θtref. For example, a map that defines the characteristics of the target steering angle θtref with respect to the magnitude | θh2 | of the steering angle θh2, such as the basic map unit 210 in the target steering torque generating unit 200a, is used to steer the target from the steering angle θh2. Find the angle θtref. Alternatively, the target steering angle θtref may be obtained by simply multiplying the steering angle θh2 by a predetermined gain.

FIG. 15 is a diagram showing a configuration example of the steering angle control unit. The steering angle control unit 920 has the same configuration as the torsion angle control unit 300 shown in FIG. 11, and inputs the target steering angle θtref and the steering angle θt instead of the target torsion angle Δθref and the torsion angle Δθ. Then, the steering angle feedback (FB) compensation unit 921, the steering angular velocity calculation unit 922, the speed control unit 923, the output limiting unit 926, and the subtraction unit 927 have the torsion angle FB compensation unit 310, the torsion angular velocity calculation unit 320, and the speed, respectively. The same operation is performed with the same configuration as the control unit 330, the output limiting unit 350, and the subtracting unit 361.

Next, an operation example in the second example will be described. FIG. 16 is a flowchart showing an operation example of the control unit of the second example shown in FIG.

When the operation is started, the angle sensor 73 detects the steering angle θt, the angle sensor (second angle sensor) 74 detects the motor angle θm (step S110), and the steering angle θt is transmitted to the steering angle control unit 920. , The motor angle θm is input to the angular velocity calculation unit 951 respectively.

The angular velocity calculation unit 951 differentiates the motor angle θm to calculate the motor angular velocity ωm, and outputs the motor angular velocity to the twist angle control unit 300a (step S120).

After that, the target steering torque generation unit 200a executes the same operation as in steps S10 to S40 shown in FIG. 6, drives the reaction force motor 61, and executes current control (steps S130 to S160).

On the other hand, in the steering angle control, the target steering angle generation unit 910 inputs the steering angle θh, and the steering angle θh is input to the limiting unit 931. The limiting unit 931 limits the upper and lower limit values of the steering angle θh by preset upper and lower limit values (step S170), and outputs the steering angle θh1 to the rate limiting unit 932. The rate limiting unit 932 limits the amount of change in the steering angle θh1 by a preset limit value (step S180), and outputs the steering angle θh2 to the correction unit 933. The correction unit 933 corrects the steering angle θh2 to obtain the target steering angle θtref (step S190), and outputs the steering angle θh2 to the steering angle control unit 920.

The steering angle control unit 920, which has input the steering angle θt and the target steering angle θtref, calculates the deviation Δθt0 by subtracting the steering angle θt from the target steering angle θtref by the subtracting unit 927 (step S200). ). The deviation Δθt0 is input to the steering angle FB compensation unit 921, and the steering angle FB compensation unit 921 compensates for the deviation Δθt0 by multiplying the deviation Δθt0 by the compensation value (step S210), and sets the target steering angular velocity ωtref. Output to the control unit 923. The steering angular velocity calculation unit 922 inputs the steering angle θt, calculates the steering angular velocity ωtt by a differential calculation with respect to the steering angle θt (step S220), and outputs the steering angular velocity ωtt to the speed control unit 923. The speed control unit 923 calculates the motor current command value Imcta by IP control in the same manner as the speed control unit 330 (step S230), and outputs the motor current command value Imcta to the output limiting unit 926. The output limiting unit 926 limits the upper and lower limit values of the motor current command value Imcta by the preset upper limit value and lower limit value (step S240), and outputs the motor current command value Imct as the motor current command value Imct (step S250).

The motor current command value Imct is input to the current control unit 930, and the current control unit 930 is based on the motor current command value Imct and the current value Imd of the drive motor 71 detected by the motor current detector 940. 71 is driven and current control is performed (step S260).

The order of data input and calculation in FIG. 16 can be changed as appropriate. Further, the speed control unit 923 in the steering angle control unit 920 is not the IP control but the PI control, the P control, the PID control, and the PI-D, like the speed control unit 330 in the twist angle control unit 300a. Control and the like are feasible, and any of P, I, and D controls may be used, and follow-up control by the steering angle control unit 920 and the twist angle control unit 300a is generally used. The control structure may be used. The steering angle control unit 920 is used in a vehicle device as long as it has a control configuration in which the actual angle (here, the steering angle θt) follows the target angle (here, the target steering angle θtref). The control configuration is not limited, and for example, the control configuration used in an industrial positioning device, an industrial robot, or the like may be applied.

In the example shown in FIG. 12, one ECU 50 controls the reaction force device 60 and the drive device 70, but an ECU for the reaction force device 60 and an ECU for the drive device 70 may be provided respectively. In this case, the ECUs transmit and receive data by communication. Further, the SBW system shown in FIG. 12 does not have a mechanical coupling between the reaction force device 60 and the drive device 70, but when an abnormality occurs in the system, the column shaft 2 and the steering mechanism are clutched or the like. The present disclosure is also applicable to SBW systems provided with a mechanical torque transmission mechanism that mechanically couples with. In such an SBW system, when the system is normal, the clutch is turned off to open the mechanical torque transmission, and when the system is abnormal, the clutch is turned on to enable the mechanical torque transmission.

Further, in the first example and the second example, the twist angle control units 300 and 300a directly calculate the motor current command value Imc and the assist current command value Iac, but first output them before calculating them. After calculating the desired motor torque (target torque), the motor current command value and the assist current command value may be calculated. In this case, in order to obtain the motor current command value and the assist current command value from the motor torque, the generally used relationship between the motor current and the motor torque is used.

(Embodiment 1)
Up to this point, the first example and the second example of the configuration in which the steering device for a vehicle is applied to an electric power steering device (EPS) have been described. Hereinafter, the steering angle processing unit 600 (see FIG. 4) of the vehicle steering device according to the first embodiment will be described.

In the configuration where the target value of the steering torque is set according to the steering angle, if the sensor that acquires the steering angle fails and the steering angle (pulse signal according to the steering angle) is not output normally, it is based on the steering angle. You lose control. In particular, in the SBW type vehicle steering device having a configuration in which the steering mechanism and the steering mechanism are controlled by an electric signal, the vehicle may fall into an unsteerable state.

In the vehicle steering device according to the present embodiment, when the steering angle sensor 14 that detects the actual steering angle θr fails, it is estimated using the motor angle θm detected by the angle sensor 15 (or the angle sensor 74). The steering angle θe is estimated, and the estimated steering angle θe is set as the steering angle θh to continue the control. The rotation angle of the motor shaft can be used as the motor angle θm.

When the so-called increment method of detecting the relative angle of the motor rotation angle is used as the sensor for detecting the motor angle θm in the present disclosure, the rotation of the motor 20 (or the reaction force motor 61) with respect to the detected value of the sensor. The motor angle θm is determined by adding an angle corresponding to the number of times. When a so-called absolute type sensor that detects the absolute angle of the motor rotation angle is used as the sensor that detects the motor angle θm, the detection value of the sensor is set to the motor angle θm.

The steering angle processing unit 600 includes an actual steering angle θr detected by the steering angle sensor 14, a steering angle abnormality determination signal θfail, a torsion bar twist angle Δθ, and a motor detected by the angle sensor 15 (or angle sensor 74). The angle θm is input.

In the present embodiment, the steering angle sensor 14 outputs, for example, a pulse signal corresponding to the steering wheel angle as the actual steering angle θr.

The steering angle abnormality determination signal θfail is a signal indicating whether or not the actual steering angle θr is normally output from the steering angle sensor 14. Specifically, for example, a steering angle abnormality flag indicating whether or not the actual steering angle θr is normally output is input to the steering angle processing unit 600 as a steering angle abnormality determination signal θfail. The steering angle abnormality determination signal θfail may be output from the steering angle sensor 14. Further, the component unit that outputs the steering angle abnormality determination signal θfail may be configured by, for example, the component unit of the control unit 30 or a circuit outside the control unit 30.

As described above, the torsion bar torsion angle Δθ is, for example, the actual steering angle θr (handle angle θ ₁ ) detected by the steering angle sensor 14 and the motor detected by the angle sensor 15 (or angle sensor 74). It is calculated by the above equation (1) as the deviation of the angle θm (column angle θ _2).

Hereinafter, the operation of the rudder angle processing unit 600 will be described with reference to FIG. FIG. 17 is a flowchart showing an example of a processing flow in the steering angle processing unit according to the first embodiment. In the processing flow shown in FIG. 17, the steering angle θh, the steering angle past value Zθh, the motor angle past value Zθm, and the twist angle past value ZΔθ are stored in, for example, the EEPROM 1004 of the ECU 30 (or ECU 50) in the previous processing. It is assumed that

The steering angle processing unit 600 has an actual steering angle θr detected by the steering angle sensor 14, a steering angle abnormality determination signal θfail, a torsion bar twist angle Δθ, and a motor angle detected by the angle sensor 15 (or angle sensor 74). Acquire θm (step S101).

The steering angle processing unit 600 determines whether or not the value of the acquired steering angle abnormality determination signal θfail is “0” (step S102). Here, when the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “1”, it indicates that the actual steering angle θr is normally output, and the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is indicated. When is "0", it means that the actual steering angle θr is not output normally.

When the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “1”, that is, when the actual steering angle θr is normally output (step S102; Yes), the steering angle processing unit 600 has acquired the actual steering angle. θr is stored as the steering angle θh (step S103), and the steering angle θh is stored as the steering angle past value Zθh (step S104). Further, the steering angle processing unit 600 stores the acquired motor angle θm as the motor angle past value Zθm, and stores the acquired twist angle Δθ as the twist angle past value ZΔθ (step S105). The steering angle θh, the steering angle past value Zθh, the motor angle past value Zθm, and the twist angle past value ZΔθ are stored in, for example, the EEPROM 1004 of the ECU 30 (or ECU 50). That is, the final values of the processing up to the previous time are stored in the steering angle θh, the steering angle past value Zθh, the motor angle past value Zθm, and the twist angle past value ZΔθ.

When the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “0”, that is, when the actual steering angle θr is not output normally (step S102; No), the steering angle processing unit 600 has the actual steering angle θr. The number of times that the rudder angle abnormality determination signal θfail was not output normally, that is, the number of abnormalities in which the rudder angle abnormality flag value of the rudder angle abnormality determination signal θfail became “0” was counted (step S106), and the rudder angle abnormality flag of the rudder angle abnormality determination signal θfail was counted. It is determined whether or not the number of abnormalities in which the value becomes “0” is “1” (step S107).

When the count number of the number of abnormalities is "1", that is, when the steering angle abnormality flag value of the steering angle abnormality determination signal θfile is "0" (step S102; No) for the first time (step S107; Yes). The rudder angle processing unit 600 stores the motor angle past value Zθm as the motor initial angle θ0, stores the twist angle past value ZΔθ as the initial twist angle Δθ0 (step S108), and proceeds to the process of step S109.

When the number of abnormal counts is "2" or more, that is, the rudder angle abnormality flag value of the steering angle abnormality determination signal θfail is "0" (step S102; No) twice or more (step). S107; No), the rudder angle processing unit 600 shifts to the process of step S109, calculates the relative angle Δθm of the motor 20, and calculates the difference Δd of the twist angle of the torsion bar (step S109). The relative angle Δθm of the motor 20 is represented by the following equation (11). The difference Δd of the twist angle of the torsion bar is expressed by the following equation (12).

Δθm = θm−θ0 ... (11)

Δd = Δθ−Δθ0 ... (12)

Then, the steering angle processing unit 600 calculates the estimated steering angle θe using the estimation calculation formula of the estimated steering angle θe shown in the following equation (13) (step S110), and stores the estimated steering angle θe as the steering angle θh. (Step S111).

θe = Zθh + Δd + Δθm × Cg ... (13)

In the above equation (13), Cg is the gear ratio in the reduction mechanism 3. According to the above equation (13), the torsion bar with respect to the steering angle past value Zθh, which is the past value of the steering angle θh when the steering angle sensor 14 is not collapsed, that is, when the steering angle sensor 14 is sound. The angle sensor 15 ( Alternatively, the estimated steering angle θe can be estimated using the motor angle θm detected by the angle sensor 74).

Then, the steering angle processing unit 600 outputs the steering angle θh stored in step S103 or step S111 to the target steering torque generating units 200 and 200a (step S112). After that, the rudder angle processing unit 600 returns to the processing of step S101 and repeats the processing flow shown in FIG. As a result, even if the rudder angle sensor 14 that detects the actual steering angle θr fails, the estimated steering angle θe is estimated using the motor angle θm detected by the angle sensor 15 (or the angle sensor 74), and the estimation is performed. The control can be continued with the steering angle θe as the steering angle θh.

According to the present embodiment, it is possible to provide a vehicle steering device capable of ensuring redundancy with respect to the steering angle.

(Embodiment 2)
FIG. 18 is a block diagram showing a configuration example of the steering angle processing unit according to the second embodiment. It should be noted that the same reference numerals are given to the configurations having the same functions as those of the first embodiment except for the steering angle processing units of the first and second examples of the configuration to which the vehicle steering device according to the second embodiment is applied. The explanation will be omitted.

The rudder angle processing unit 600a according to the second embodiment shown in FIG. 18 is different from the first embodiment in that the rudder angle processing unit 600a includes an estimated rudder angle calculation unit 601 and a switching unit 602.

When the actual steering angle θr is not normally output from the steering angle sensor 14, that is, the steering angle abnormality determination signal θfail is the steering angle abnormality determination signal θfail, and the steering angle abnormality flag value is “0”. When ", the estimated steering angle θe is estimated using the motor angle θm detected by the angle sensor 15 (or the angle sensor 74).

The switching unit 602 switches between the actual steering angle θr output from the steering angle sensor 14 and the estimated steering angle θe output from the estimated steering angle calculation unit 601 based on the steering angle abnormality determination signal θfail, and the steering angle θh Output as.

Specifically, in the switching unit 602, when the actual steering angle θr is normally output from the steering angle sensor 14, that is, the steering angle abnormality determination signal θfail is the steering angle abnormality determination signal θfail, and the steering angle abnormality flag value is “. When it is 1 ”, the actual steering angle θr output from the steering angle sensor 14 is output to the target steering torque generating units 200 and 200a as the steering angle θh.

Further, in the switching unit 602, when the actual steering angle θr is not normally output from the steering angle sensor 14, that is, the steering angle abnormality determination signal θfail has a steering angle abnormality flag value of “0” in the steering angle abnormality determination signal θfail. When, the estimated steering angle θe output from the estimated steering angle calculation unit 601 is output to the target steering torque generating units 200 and 200a as the steering angle θh.

Hereinafter, the operation of the rudder angle processing unit 600a will be described with reference to FIGS. 19 and 20. FIG. 19 is a flowchart showing an example of the calculation processing flow of the estimated steering angle in the estimated steering angle calculation unit of the steering angle processing unit according to the second embodiment. FIG. 20 is a flowchart showing an example of a switching processing flow between the actual steering angle and the estimated steering angle in the switching unit of the steering angle processing unit according to the second embodiment. In the calculation processing flow of the estimated steering angle θe shown in FIG. 19, the steering angle θh, the steering angle past value Zθh, the motor angle past value Zθm, and the twist angle past value ZΔθ are obtained in the previous processing, as in the first embodiment. For example, it is assumed that it is stored in the EEPROM 1004 of the ECU 30 (or the ECU 50). That is, the final values of the processing up to the previous time are stored in the steering angle θh, the steering angle past value Zθh, the motor angle past value Zθm, and the twist angle past value ZΔθ.

First, the calculation processing flow of the estimated steering angle θe in the estimated steering angle calculation unit 601 will be described with reference to FIG.

The estimated steering angle calculation unit 601 is a motor detected by the actual steering angle θr detected by the steering angle sensor 14, the steering angle abnormality determination signal θfail, the torsion bar torsion angle Δθ, and the angle sensor 15 (or the angle sensor 74). The angle θm is acquired (step S201).

The estimated rudder angle calculation unit 601 determines whether or not the value of the acquired rudder angle abnormality determination signal θfail is “0” (step S202). Here, when the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “1”, it indicates that the actual steering angle θr is normally output, and the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is indicated. When is "0", it means that the actual steering angle θr is not output normally.

When the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “1”, that is, when the actual steering angle θr is normally output (step S202; Yes), the estimated steering angle calculation unit 601 obtains the actual steering angle. The angle θr is stored as the steering angle θh (step S203), and the steering angle θh is stored as the steering angle past value Zθh (step S204). Further, the estimated steering angle calculation unit 601 stores the acquired motor angle θm as the motor angle past value Zθm, and stores the acquired twist angle Δθ as the twist angle past value ZΔθ (step S205), and performs the process in step S201. return. The steering angle θh, the steering angle past value Zθh, the motor angle past value Zθm, and the twist angle past value ZΔθ are stored in, for example, the EEPROM 1004 of the ECU 30 (or ECU 50).

When the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “0”, that is, when the actual steering angle θr is not output normally (step S202; No), the estimated steering angle calculation unit 601 performs the actual steering angle θr. Is not output normally, that is, the number of abnormalities in which the rudder angle abnormality flag value of the rudder angle abnormality determination signal θfail becomes “0” is counted (step S206), and the rudder angle abnormality of the rudder angle abnormality determination signal θfail is counted. It is determined whether or not the number of abnormalities in which the flag value is “0” is “1” (step S207).

When the count number of the number of abnormalities is "1", that is, when the steering angle abnormality flag value of the steering angle abnormality determination signal θfile is "0" (step S202; No) for the first time (step S207; Yes). The estimated rudder angle calculation unit 601 stores the motor angle past value Zθm as the motor initial angle θ0, stores the twist angle past value ZΔθ as the initial twist angle Δθ0 (step S208), and proceeds to the process of step S209.

When the number of abnormal counts is "2" or more, that is, the rudder angle abnormality flag value of the steering angle abnormality determination signal θfail is "0" (step S102; No) twice or more (step). S207; No), the estimated rudder angle calculation unit 601 shifts to the process of step S209, calculates the relative angle Δθm of the motor 20 using the above equation (11), and uses the above equation (12) to calculate the relative angle Δθm. The difference Δd of the twist angle of the torsion bar is calculated (step S209).

Then, the estimated steering angle calculation unit 601 calculates the estimated steering angle θe using the estimation calculation formula of the estimated steering angle θe shown in the above equation (13) (step S210), and sets the estimated steering angle θe as the steering angle θh. Output (step S211), the process returns to the process of step S201, and the process flow shown in FIG. 19 is repeated.

Next, the switching processing flow between the actual steering angle θr and the estimated steering angle θe in the switching unit 602 will be described with reference to FIG.

The switching unit 602 determines whether or not the value of the steering angle abnormality determination signal θfile is “0” (step S301). When the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “1”, that is, when the actual steering angle θr is normally output (step S301; Yes), the switching unit 602 is output from the steering angle sensor 14. The actual steering angle θr is set as the steering angle θh (step S302), and is output to the target steering torque generating units 200 and 200a (step S304).

When the steering angle abnormality flag value of the steering angle abnormality determination signal θfail is “1”, that is, when the actual steering angle θr is normally output (step S301; No), the switching unit 602 is referred to from the estimated steering angle calculation unit 601. The output estimated steering angle θe is set as the steering angle θh (step S303), and the steering angle θh is output to the target steering torque generating units 200 and 200a (step S304).

After that, the switching unit 602 returns to the process of step S301 and repeats the process flow shown in FIG.

Even if the rudder angle sensor 14 that detects the actual steering angle θr fails due to the processing flow shown in FIGS. 19 and 20 described above, the motor angle θm detected by the angle sensor 15 (or the angle sensor 74) is used. It is possible to estimate the estimated steering angle θe and continue the control with the estimated steering angle θe as the steering angle θh.

In the configuration of the present embodiment, the calculation process of the estimated steering angle θe shown in FIG. 19 and the switching process of the actual steering angle θr and the estimated steering angle θe shown in FIG. 20 can be separated. Further, since the estimated steering angle θe is calculated when the actual steering angle θr is not output, it is possible to reduce the processing when the actual steering angle θr is output.

According to the present embodiment, it is possible to provide a vehicle steering device capable of ensuring redundancy with respect to the steering angle.

The figures used above are conceptual diagrams for qualitatively explaining the present disclosure, and are not limited thereto. Further, the above-described embodiment is an example of a preferred embodiment of the present disclosure, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present disclosure. Further, as long as the mechanism has an arbitrary spring constant between the handle and the motor or the reaction force motor, the mechanism may not be limited to the torsion bar.

1 Handle 2 Column shaft 2A Torque bar 3 Deceleration mechanism 4a, 4b Universal joint 5 Pinion rack mechanism 6a, 6b Tie rod 7a, 7b Hub unit 8L, 8R Steering wheel 10 Torque sensor 11 Ignition key 12 Vehicle speed sensor 13 Battery 14 Steering angle sensor (1st angle sensor)
15 Angle sensor (2nd angle sensor)
20 Motor 30,50 Control unit (ECU)
60 Reaction force device 61 Reaction force motor 70 Drive device 71 Drive motor 72 Gear 73 Angle sensor 74 Angle sensor (second angle sensor)
100 EPS Steering system / Vehicle system 130 Current control unit 140 Motor current detector 200, 200a Target steering torque generator 210 Basic map unit 211 Multiplication unit 220 Differentiation unit 230 Damper gain map unit 240 Hysteresis correction unit 261,262 Addition unit 300, 300a Twist angle control unit 310 Twist angle feedback (FB) compensation unit 320 Twist angular velocity calculation unit 330 Speed control unit 331 Integration unit 332 Proportional unit 333,334 Subtraction unit 350 Output limit unit 361 Subtraction unit 400 Steering direction determination unit 500 Conversion unit 600 , 600a Steering angle processing unit 601 Estimated steering angle calculation unit 602 Switching unit 910 Target steering angle generation unit 920 Steering angle control unit 921 Steering angle feedback (FB) Compensation unit 922 Steering angular velocity calculation unit 923 Speed control unit 926 Output Limiting unit 927 Subtraction unit 930 Current control unit 931 Limiting unit 933 Correction unit 932 Rate limiting unit 940 Motor current detector 951 Angular velocity calculation unit 1001 CPU
1005 Interface 1006 A / D Converter 1007 PWM Controller 1100 Control Computer (MCU)

Claims (4)

A vehicle steering device that assists and controls the steering system of a vehicle via a deceleration mechanism by driving and controlling a motor that assists the steering force.
The torsion bar provided on the column axle of the vehicle and
The first angle sensor that detects the actual steering angle and
A second angle sensor that detects the motor angle,
When the actual steering angle is output from the first angle sensor, the actual steering angle is output as the steering angle, and when the actual steering angle is not output from the first angle sensor, the second angle sensor is output. A rudder angle processing unit that outputs an estimated value estimated based on the motor angle output from
A target steering torque generating unit that generates a target steering torque when assisting and controlling the steering system based on the steering angle.
A conversion unit that converts the target steering torque into a target twist angle,
A twist angle control unit that calculates a current command value of the motor so that the twist angle of the torsion bar, which is determined based on the difference between the steering angle and the motor angle, becomes the target twist angle.
Vehicle steering device equipped with. The rudder angle processing unit
The final value of the actual steering angle when the actual steering angle is output from the first angle sensor, the final value of the motor angle output from the second angle sensor, and the final value of the torsion angle of the torsion bar. Hold and
When the actual steering angle is no longer output from the first angle sensor, the difference between the final value of the torsion angle of the torsion bar and the torsion angle of the torsion bar with respect to the final value of the actual steering angle, and the motor. The estimated value is obtained by adding the relative angle between the final value of the angle and the motor angle output from the second angle sensor and the value converted into the relative angle of the steering angle by multiplying the gear ratio of the reduction mechanism. The vehicle steering device according to claim 1 for calculation. The rudder angle processing unit
An estimated rudder angle calculation unit that calculates the estimated value,
A switching unit that switches between the actual steering angle output from the first angle sensor and the estimated value output from the estimated steering angle calculation unit and outputs the output to the target steering torque generation unit.
The vehicle steering device according to claim 2. The estimated rudder angle calculation unit
When the actual steering angle is not output from the first angle sensor, the estimated value is calculated.
The switching unit is
When the actual steering angle is output from the first angle sensor, the actual steering angle is output as the steering angle to the target steering torque generation unit.
The vehicle steering device according to claim 3, wherein when the actual steering angle is not output from the first angle sensor, the estimated value is output to the target steering torque generating unit as the steering angle.

Images