Motor control device

Abstract

In the present invention, a control unit includes: a base torque command value calculation unit that calculates a base torque command value on the basis of an integrated angle command value; a disturbance torque estimation unit for calculating a disturbance torque estimation value, which is an estimation value of a torque other than a motor torque that is applied to a drive target of an electric motor; a disturbance torque compensation unit that corrects the base torque command value by using, in principle, the disturbance torque estimation value and outputs a post-compensation torque command value; and a failure determination unit that determines whether or not the disturbance torque estimation unit is in a failed state, and, upon determining that the disturbance torque estimation unit is in a failed state, sets the disturbance torque estimation value to be used by the disturbance torque compensation unit to zero.

Description

Motor control device

[0001] This disclosure relates to a motor control device.

[0002] Patent Document 1 discloses a motor control device that includes a manual steering angle command value generation unit that generates a manual steering angle command value using steering torque, an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering angle command value to the automatic steering angle command value, and a control unit that angle-controls an electric motor based on the integrated angle command value.

[0003] The control unit includes a basic torque command value calculation unit that calculates a basic torque command value based on an integrated angle command value, a disturbance torque estimation unit (disturbance observer) that estimates disturbance torque, which is torque other than the motor torque of the electric motor acting on the object driven by the electric motor, and a disturbance torque compensation unit that corrects the basic torque command value with the disturbance torque.

[0004] International Publication No. 2023 / 286169

[0005] Even if a failure is detected in the disturbance torque estimation unit, a redundant system allows for the continuation of ADAS (Advanced Driver-Assistance Systems) control by stopping the operation of the faulty system (one of two systems containing the disturbance torque estimation unit) and continuing control with the remaining system. ADAS control includes driver assistance control and automated driving control.

[0006] However, in a non-redundant system, if a malfunction in the disturbance torque estimation unit is detected and the control of the electric motor is stopped, ADAS control cannot be continued.

[0007] The purpose of this disclosure is to provide a motor control device that enables the continuation of ADAS control when a failure of the disturbance torque estimation unit is detected in a non-redundant system.

[0008] One embodiment of the present disclosure provides a motor control device for driving and controlling an electric motor for steering angle control, comprising: a manual steering angle command value generation unit that generates a manual steering angle command value using steering torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering angle command value to an automatic steering angle command value; and a control unit that controls the electric motor based on the integrated angle command value, wherein the control unit comprises: a basic torque command value calculation unit that calculates a basic torque command value based on the integrated angle command value; a disturbance torque estimation unit that calculates a disturbance torque estimation value which is an estimated value of torque other than motor torque applied to the target of the electric motor's drive; a disturbance torque compensation unit that basically corrects the basic torque command value using the disturbance torque estimation value and outputs a compensated torque command value; and a failure determination unit that determines whether the disturbance torque estimation unit is malfunctioning and sets the disturbance torque estimation value used in the disturbance torque compensation unit to zero when it is determined that the disturbance torque estimation unit is malfunctioning.

[0009] In this configuration, ADAS control can continue even when a failure in the disturbance torque estimation unit is detected in a non-redundant system.

[0010] Figure 1 is a schematic diagram showing the general configuration of an electric power steering system to which a motor control device according to an embodiment of this disclosure is applied. Figure 2 is a block diagram for explaining the electrical configuration of the motor control ECU. Figure 3 is a block diagram for explaining the electrical configuration of the angle control unit. Figure 4 is a schematic diagram showing an example of the configuration of a physical model of the electric power steering system. Figure 5 is a block diagram showing the configuration of the disturbance torque estimation unit. Figure 6 is a block diagram showing the configuration of the fault determination unit. Figure 7 is a flowchart showing the procedure of the first fault determination process by the first fault determination unit. Figure 8A shows the estimated error T ｔｄ＿ｅｒｒｏｒ This is a time chart showing an example, and Figure 8B shows the estimated value of the first disturbance torque^T. ｔｄ１ and disturbance torque estimate ^T ｔｄ This is a time chart showing an example. Figure 9A shows the estimated error T ｔｄ＿ｅｒｒｏｒ This is a time chart showing an example, and Figure 9B shows the estimated value of the first disturbance torque^T. ｔｄ１ and disturbance torque estimate ^Tｔｄ is a time chart showing an example. FIG. 10 is a flowchart illustrating a procedure of second failure determination processing performed by a second failure determination unit. FIG. 11A illustrates an estimation error T ｔｄ＿ｅｒｒｏｒ and is a time chart showing an example; FIG. 11B is a time chart showing an example of a first count value C1; FIG. 11C is a time chart showing an example of a second count value C2; FIG. 11D illustrates a disturbance torque estimated value ^T ｔｄ and a second disturbance torque estimated value ^T ｔｄ２ and is a time chart showing an example.

[0011] [Description of Embodiments of the Present Disclosure] An embodiment of the present disclosure is a motor control device for driving and controlling an electric motor for steering angle control, comprising: a manual steering angle command value generation unit that generates a manual steering angle command value using steering torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering angle command value to an automatic steering angle command value; and a control unit that controls the electric motor based on the integrated angle command value. The control unit includes: a basic torque command value calculation unit that calculates a basic torque command value based on the integrated angle command value; a disturbance torque estimation unit for calculating a disturbance torque estimated value, which is an estimated value of torque other than motor torque applied to a driven object of the electric motor; a disturbance torque compensation unit that basically corrects the basic torque command value using the disturbance torque estimated value and outputs a corrected torque command value; and a failure determination unit that determines whether the disturbance torque estimation unit has a failure, and sets the disturbance torque estimated value used in the disturbance torque compensation unit to zero when it is determined that the disturbance torque estimation unit has a failure.

[0012] With this configuration, in a non-redundant system, ADAS control can be continued when a failure of the disturbance torque estimation unit is detected.

[0013] In an embodiment of the present disclosure, the failure determination unit calculates a disturbance torque comparison value by a method different from that of the disturbance torque estimation unit, and determines whether the disturbance torque estimation unit has a failure based on an estimation error that is an absolute value of a difference between the disturbance torque estimated value and the disturbance torque comparison value.

[0014] In one embodiment of the present disclosure, the disturbance torque estimation unit calculates the disturbance torque estimate by an operation including an integral operation, and the fault determination unit calculates the disturbance torque comparison value by an operation that does not include an integral operation.

[0015] In one embodiment of the present disclosure, the failure determination unit is configured to set the disturbance torque comparison value as the disturbance torque estimate value used in the disturbance torque compensation unit when it determines that the disturbance torque estimation unit is malfunctioning, and thereafter, when the malfunction state of the disturbance torque estimation unit continues for a predetermined time or longer, it sets the disturbance torque estimate value used in the disturbance torque compensation unit to zero.

[0016] In one embodiment of the present disclosure, a state in which the estimation error is less than or equal to a first threshold is defined as a first state, and a state in which the estimation error is greater than the first threshold is defined as a second state. The fault determination unit, when a change occurs from the first state to the second state at a certain point in time, and the second state continues for a period of time that is longer than a first predetermined time but less than a second predetermined time, sets the estimated disturbance torque at that point in time as the estimated disturbance torque used by the disturbance torque compensation unit, and sets the estimated disturbance torque used by the disturbance torque compensation unit to zero when the second state continues for a second predetermined time or longer.

[0017] In one embodiment of the present disclosure, if the state in which the estimation error is less than or equal to a second threshold is defined as a third state, and the state in which the estimation error is greater than the second threshold is defined as a fourth state, the fault determination unit sets the disturbance torque estimate used in the disturbance torque compensation unit to zero when, at some point in time, the state changes from the third state to the fourth state, and the third state does not continue for more than a third predetermined time, and the cumulative value of the time in the fourth state from that point in time reaches a fourth predetermined time that is longer than the third predetermined time.

[0018] In one embodiment of the present disclosure, if the state in which the estimation error is less than or equal to a first threshold is defined as a first state, and the state in which the estimation error is greater than the first threshold is defined as a second state, the fault determination unit sets the disturbance torque estimate value used in the disturbance torque compensation unit to zero when the state changes from the first state to the second state at a certain point in time, and the second state continues for a fifth predetermined time from that point in time.

[0019] [Detailed Description of Embodiments of the Disclosure] Embodiments of the Disclosure will be described in detail below with reference to the accompanying drawings.

[0020] Figure 1 is a schematic diagram showing the general configuration of an electric power steering system to which a motor control device according to the present disclosure is applied.

[0021] The electric power steering system 1 comprises a steering wheel (handle) 2 as a steering member for steering the vehicle, a steering mechanism 4 that steers the steering wheels 3 in conjunction with the rotation of the steering wheel 2, and a steering assist mechanism 5 for assisting the driver's steering. The steering wheel 2 and the steering mechanism 4 are mechanically connected via a steering shaft 6 and an intermediate shaft 7.

[0022] The steering shaft 6 includes an input shaft 8 connected to the steering wheel 2 and an output shaft 9 connected to the intermediate shaft 7. The input shaft 8 and the output shaft 9 are connected via a torsion bar 10 so as to be rotatable relative to each other.

[0023] A torque sensor 12 is positioned near the torsion bar 10. The torque sensor 12 measures the torsion bar torque (steering torque) T applied to the steering wheel 2 based on the relative rotational displacement of the input shaft 8 and the output shaft 9. ｔｂ The torsion bar torque T detected by the torque sensor 12 is detected. In this embodiment, the torsion bar torque T is detected by the torque sensor 12. ｔｂ For example, the torque for steering to the left is detected as a positive value, and the torque for steering to the right is detected as a negative value, and the larger the absolute value, the greater the torsion bar torque T. ｔｂ Assume that the size of will increase.

[0024] The steering mechanism 4 consists of a rack and pinion mechanism including a pinion shaft 13 and a rack shaft 14 as the steering axis. Steering wheels 3 are connected to each end of the rack shaft 14 via tie rods 15 and knuckle arms (not shown). The pinion shaft 13 is connected to the intermediate shaft 7. The pinion shaft 13 rotates in conjunction with the steering of the steering wheel 2. A pinion 16 is connected to the tip of the pinion shaft 13.

[0025] The rack shaft 14 extends linearly along the left-right direction of the vehicle. A rack 17 that meshes with the pinion 16 is formed in the axial middle portion of the rack shaft 14. The rotation of the pinion shaft 13 is converted into axial movement of the rack shaft 14 by the pinion 16 and the rack 17. By moving the rack shaft 14 in the axial direction, the steering wheels 3 can be steered.

[0026] When the steering wheel 2 is steered (rotated), this rotation is transmitted to the pinion shaft 13 via the steering shaft 6 and the intermediate shaft 7. The rotation of the pinion shaft 13 is then converted into axial movement of the rack shaft 14 by the pinion 16 and the rack 17. This causes the steering wheel 3 to turn.

[0027] The steering assist mechanism 5 includes an electric motor 18 for generating steering assist force (assist torque) and a reduction gear 19 for amplifying the output torque of the electric motor 18 and transmitting it to the steering mechanism 4. The reduction gear 19 consists of a worm gear mechanism including a worm gear 20 and a worm wheel 21 that meshes with the worm gear 20. The reduction gear 19 is housed in a gear housing 22 which serves as a transmission mechanism housing.

[0028] In the following, the reduction ratio (gear ratio) of the reducer 19 will be denoted by N. The reduction ratio N is equal to the worm wheel angle θ, which is the rotation angle of the worm wheel 21. ｗｗ The worm gear angle θ is the rotation angle of the worm gear 20 relative to the given value. ｗｇ The ratio (θ) ｗｇ / θ ｗｗ ) is defined as.

[0029] The worm gear 20 is rotationally driven by the electric motor 18. The worm wheel 21 is also integrally rotatably connected to the output shaft 9.

[0030] When the worm gear 20 is rotationally driven by the electric motor 18, the worm wheel 21 is rotationally driven, applying motor torque to the steering shaft 6 and causing the steering shaft 6 (output shaft 9) to rotate. The rotation of the steering shaft 6 is then transmitted to the pinion shaft 13 via the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into axial movement of the rack shaft 14. This causes the steering wheels 3 to turn. In other words, by rotationally driving the worm gear 20 with the electric motor 18, steering assistance by the electric motor 18 and steering of the steering wheels 3 become possible. The electric motor 18 is equipped with a rotation angle sensor 23 for detecting the rotation angle of the rotor of the electric motor 18.

[0031] The torque applied to the output shaft 9 (an example of what the electric motor 18 drives) consists of the motor torque from the electric motor 18 and the disturbance torque T other than the motor torque. ｔｄ There is also the motor torque and other disturbance torque T. ｔｄ Torsion bar torque T ｔｂ Road surface reaction torque (road surface load torque) T ｒｌ , friction torque T ｆ This includes, etc.

[0032] Torsion bar torque T ｔｂ This is the torque applied from the steering wheel 2 to the output shaft 9 by the force applied to the steering wheel 2 by the driver, the force generated by the steering wheel inertia, etc.

[0033] Road surface reaction torque T ｒｌ This is the torque applied to the output shaft 9 via the rack shaft 14 from the steering wheel 3 side, due to the self-aligning torque generated in the tires, the force generated by the suspension and tire-wheel alignment, the frictional force of the rack and pinion mechanism, etc.

[0034] The vehicle is equipped with a CCD (Charge Coupled Device) camera 25 that photographs the road ahead in the direction of travel, a GPS (Global Positioning System) 26 for detecting the vehicle's position, a radar 27 for detecting road shape and obstacles, and a map information memory 28 that stores map information.

[0035] The CCD camera 25, GPS 26, radar 27, and map information memory 28 are connected to a higher-level ECU (Electronic Control Unit) 201 for performing ADAS control (driver assistance control, autonomous driving control, etc.). Based on the information obtained from the CCD camera 25, GPS 26, and radar 27, as well as map information, the higher-level ECU 201 performs surrounding environment recognition, vehicle position estimation, route planning, etc., and determines control target values ​​for steering and drive actuators.

[0036] In this embodiment, the higher-level ECU 201 sets the automatic steering angle command value θ for automatic steering. ＡＤ Set the following. In this embodiment, automatic steering control is, for example, control to make the vehicle travel along a target driving line (target trajectory). Automatic steering angle command value θ ＡＤ This is the target value for the steering angle required to automatically drive the vehicle along the target driving line.

[0037] In this embodiment, the automatic steering angle command value θ ＡＤ This is expressed as the amount of rotation (rotation angle) from the neutral position of the output shaft 9, where a rotation amount to the left from the neutral position is represented as a positive value, and a rotation amount to the right from the neutral position is represented as a negative value. Automatic steering angle command value θ ＡＤ This is set, for example, based on vehicle speed, lateral deviation from the target driving line, and yaw deviation of the vehicle from the target driving line. Such an automatic steering angle command value θ ＡＤ The process for setting this is well-known, so a detailed explanation will be omitted here.

[0038] Automatic steering control (driving assistance control) may include, for example, lane centering assist (LCA) control, which assists steering to keep the vehicle in the center of the driving lane, or lane keeping assist (LKA) control, which assists steering to keep the vehicle within the driving lane.

[0039] Auto steering angle command value θ ＡＤ This is provided to the motor control ECU 202 via the in-vehicle network. Torsion bar torque T detected by torque sensor 12 ｔｂ The output signal from the rotation angle sensor 23 is input to the motor control ECU 202. The motor control ECU 202 controls the electric motor 18 based on these input signals and information provided by the higher-level ECU 201.

[0040] Figure 2 is a block diagram illustrating the electrical configuration of the motor control ECU 202.

[0041] The motor control ECU 202 includes a microcomputer 50, a drive circuit (inverter circuit) 41 controlled by the microcomputer 50 that supplies power to the electric motor 18, and the current (hereinafter referred to as "motor current I") that flows through the electric motor 18. ｍ It includes a current detection circuit 42 for detecting the following:

[0042] The microcomputer 50 is equipped with a CPU and memory (ROM, RAM, non-volatile memory, etc.) and functions as multiple function processing units by executing a predetermined program. The multiple function processing units include a rotation angle calculation unit 51, a reduction ratio division unit 52, a manual steering angle command value generation unit 53, an integrated angle command value calculation unit 54, an angle control unit 55, and a torque control unit (current control unit) 56.

[0043] The microcomputer 50 generates a motor torque command value T at predetermined calculation cycles. ｍ，ｃｍｄ The motor torque command value T is calculated and obtained. ｍ，ｃｍｄ The drive circuit 41 is controlled based on this.

[0044] The rotation angle calculation unit 51 calculates the rotor rotation angle θ of the electric motor 18 based on the output signal of the rotation angle sensor 23.ｍ The reduction ratio division unit 52 calculates the rotor rotation angle θ. ｍ By dividing by the reduction ratio N, the rotor rotation angle θ is obtained. ｍ The rotation angle (actual steering angle) of the output shaft 9 is θ ｐ Convert to the actual steering angle θ. In this embodiment, the actual steering angle θ ｐ This is expressed as the amount of rotation (rotation angle) from the neutral position of the output shaft 9, with a positive value representing rotation in the left steering direction from the neutral position, and a negative value representing rotation in the right steering direction from the neutral position.

[0045] The manual steering angle command value generation unit 53 basically generates a steering angle (more precisely, the rotation angle θ of the output shaft 9) corresponding to the steering wheel operation when the driver operates the steering wheel 2. ｐ ) to the manual steering angle command value θ ＭＤ It is provided for generating the torsion bar torque T detected by the torque sensor 12. The manual steering angle command value generation unit 53 generates the torsion bar torque T ｔｂ Based on this, the manual steering angle command value θ ＭＤ Generates.

[0046] The manual steering angle command value generation unit 53 includes an assist torque command value setting unit 57 and a manual steering angle command value setting unit 58. The assist torque command value setting unit 57 sets the assist torque command value T, which is the target value of the assist torque required for manual operation. ａｓ The assist torque command value setting unit 57 sets the torsion bar torque T ｔｂ Based on this, the assist torque command value T ａｓ Set it.

[0047] As the assist torque command value setting unit 57, for example, the assist torque command value setting unit (51) shown in Figure 2 of International Publication No. 2023 / 286169 (Patent Document 1) can be used. In that case, the torsion bar torque T ｔｂ Assist torque command value T ａｓ As an example of the settings, the example shown in Figure 3 of International Publication No. 2023 / 286169 can be used. The assist torque command value setting unit 57 is set to the torsion bar torque T ｔｂ And the assist torque command value T takes into account the vehicle speed.ａｓ The setting may also be configured. In addition, the assist torque command value setting unit 57 sets the torsion bar torque T ｔｂ By multiplying by a preset constant, the assist torque command value T is obtained. ａｓ You may perform the calculation.

[0048] The manual steering angle command value setting unit 58 sets the torsion bar torque T detected by the torque sensor 12. ｔｂ The assist torque command value T set by the assist torque command value setting unit 57. ａｓ Then, using the virtual load spring stiffness coefficient k and the virtual load viscous damping coefficient c, the manual steering angle command value θ is calculated. ＭＤ The virtual load spring stiffness coefficient k and virtual load viscous damping coefficient c are set in advance.

[0049] As the manual steering angle command value setting unit 58, for example, the manual steering command value generation unit (52) shown in Figure 2 of International Publication No. 2023 / 286169 (Patent Document 1) can be used. In that case, the manual steering angle command value setting unit 58 solves the differential equation (1) below to obtain the manual steering angle command value θ ＭＤ Perform the calculation.

[0050]

[0051] In equation (1), J ｃ For example, the inertia of the lower column, including the output shaft 9 and the worm wheel 21, can be used.

[0052] The integrated angle command value calculation unit 54 calculates the automatic steering angle command value θ ＡＤ The manual steering angle command value θ ＭＤ Adding this, the integrated angle command value θ ｃｍｄ Perform the calculation.

[0053] The angle control unit 55 controls the actual steering angle θ calculated by the reduction ratio division unit 52. ｐ The integrated angle command value θ ｃｍｄ (=θ) ＡＤ +θ ＭＤ ) performs control to make it follow the integrated angle command value θ. Specifically, the angle control unit 55 controls the integrated angle command value θ ｃｍｄ and the actual steering angle θ ｐ Based on this, the integrated angle command value θ ｃｍｄMotor torque command value T corresponding to the command value T ｍ，ｃｍｄ The following calculation is performed. Details of the angle control unit 55 will be described later.

[0054] The torque control unit 56 controls the motor torque of the electric motor 18 when it reaches the motor torque command value T. ｍ，ｃｍｄ The drive circuit 41 is controlled to follow the torque control. As the torque control unit 56, for example, the torque control unit (55) shown in Figures 2 and 8 of International Publication No. 2023 / 286169 (Patent Document 1) can be used. In that case, the torque control unit 56 receives the motor torque command value T ｍ，ｃｍｄ The current command value is calculated by dividing by the torque coefficient of the electric motor 18. Then, the torque control unit 56 uses the motor current I detected by the current detection circuit 42 to determine the current command value. ｍ Feedback control is performed so that it follows the current command value.

[0055] Figure 3 is a block diagram illustrating the electrical configuration of the angle control unit 55.

[0056] The angle control unit 55 includes a low-pass filter (LPF) 61, a feedback control unit 62, a feedforward control unit 63, a torque addition unit 64, a disturbance torque estimation unit (disturbance observer) 65, a fault determination unit 66, a disturbance torque compensation unit 67, and a reduction ratio division unit 68.

[0057] The low-pass filter 61 uses an integrated angle command value θ. ｃｍｄ A low-pass filter is applied to this value. The integrated angle command value θ after low-pass filtering is then applied. ｃｍｄｌ This is supplied to the feedback control unit 62 and the feedforward control unit 63. Note that the low-pass filter 61 is not required.

[0058] The feedback control unit 62 controls the actual steering angle θ. ｐ The integrated angle command value θ after low-pass filtering. ｃｍｄｌ It is provided to track the movement. The feedback control unit 62 includes an angle deviation calculation unit 62A and a PD control unit 62B. The angle deviation calculation unit 62A calculates the integrated angle command value θ ｃｍｄｌ and the actual steering angle θ ｐ The deviation Δθ (=θ) ｃｍｄｌ-θ ｐ is calculated.

[0059] The PD control unit 62B performs PD calculation (proportional-derivative calculation) on the angular deviation Δθ calculated by the angular deviation calculation unit 62A, thereby obtaining a feedback control torque T ｆｂ is calculated. The feedback control torque T ｆｂ is provided to a torque addition unit 64.

[0060] The feedforward control unit 63 is provided to compensate for a delay in responsiveness caused by the inertia of the electric power steering system 1 and improve control responsiveness. The feedforward control unit 63 includes an angular acceleration calculation unit 63A and an inertia multiplication unit 63B. The angular acceleration calculation unit 63A calculates the integrated angle command value θ ｃｍｄｌ by second-order differentiation to obtain a target angular acceleration d ２ θ ｃｍｄｌ / dt ２ is calculated.

[0061] The inertia multiplication unit 63B multiplies the target angular acceleration d ２ θ ｃｍｄｌ / dt ２ calculated by the angular acceleration calculation unit 63A by the inertia J of the electric power steering system 1, thereby obtaining a feedforward control torque T ｆｆ (= J·d ２ θ ｃｍｄｌ / dt ２ ) is calculated. The inertia J is obtained, for example, from a physical model (see FIG. 4) of the electric power steering system 1 described later. The feedforward control torque T ｆｆ is provided to the torque addition unit 64 as an inertia compensation value.

[0062] The torque addition unit 64 adds the feedback control torque T ｆｂ and the feedforward control torque T ｆｆ , thereby calculating a basic torque command value (T ｆｂ + T ｆｆ ), which is a basic torque command value for the output shaft 9.

[0063] The disturbance torque estimating unit 65 is provided to estimate nonlinear torque (disturbance torque) generated as a disturbance in a plant (a driven object of the electric motor 18). In other words, the disturbance torque estimating unit 65 estimates disturbance torque T, which is torque other than motor torque applied to the plant ｔｄ and is provided for this purpose.

[0064] In this embodiment, the disturbance torque estimating unit 65 estimates disturbance torque T ｐ，ｃｍｄ , steering angle θ ｐ , based on an output shaft torque command value T ｔｄ and an actual steering angle θ, which will be described later. The disturbance torque estimating unit 65 also estimates steering angle θ ｐ and steering angular velocity (steering angle differential value) dθ ｐ / dt.

[0065] The disturbance torque T ｔｄ , steering angle θ ｐ and steering angular velocity dθ ｐ / dt estimated by the disturbance torque estimating unit 65 may be referred to as a disturbance torque estimated value ^T ｔｄ , a steering angle estimated value ^θ ｐ and an estimated steering angular velocity d^θ ｐ / dt, respectively. Details of the disturbance torque estimating unit 65 will be described later.

[0066] The failure determination unit 66 determines whether the disturbance torque estimating unit 65 has failed based on the disturbance torque estimated value ^T ｔｄ , a motor torque command value T ｍ，ｃｍｄ and the actual steering angle θ ｐ , and outputs a final disturbance torque estimated value ^T ｔｄｆ according to the determination result. Details of the failure determination unit 66 will be described later.

[0067] The disturbance torque compensation unit 67 calculates an output shaft torque command value T ｆｂ +T ｆｆ ) by subtracting the final disturbance torque estimated value ^T ｔｄｆ from a basic torque command value (T ｐ，ｃｍｄ (= T ｆｂ +T ｆｆ -^T ｔｄｆ ). The output shaft torque command value T ｐ，ｃｍｄ is a torque command value for the output shaft 9.

[0068] Output shaft torque command value T ｐ，ｃｍｄ This is supplied to the reduction ratio division unit 68. The reduction ratio division unit 68 receives the output shaft torque command value T ｐ，ｃｍｄ By dividing by the reduction ratio N, the motor torque command value T is obtained. ｍ，ｃｍｄ The torque command value for the electric motor 18 is calculated.

[0069] The disturbance torque estimation unit 65 will be explained in detail.

[0070] The disturbance torque estimation unit 65 calculates the output shaft torque command value T calculated by the disturbance torque compensation unit 67 (see Figure 3) in the previous calculation cycle. ｐ，ｃｍｄ (=N.T.) ｍ，ｃｍｄ ) and the actual steering angle θ calculated by the reduction ratio division unit 52 (see Figure 2) in this calculation cycle. ｐ Based on this, the disturbance torque estimate ^T ｔｄ , steering angle estimated value^θ ｐ and steering angular velocity estimate d^θ ｐ Calculate / dt.

[0071] The disturbance torque estimation unit 65 uses, for example, the physical model 300 of the electric power steering system 1 shown in Figure 4 to estimate the disturbance torque. ｔｄ , ^θ ｐ and d^θ ｐ It consists of a disturbance observer that calculates / dt.

[0072] This physical model 300 includes a plant (motor-driven object) 301 which includes an output shaft 9 and a worm wheel 21 fixed to the output shaft 9. The plant 301 is supplied with torsion bar torque T via a torsion bar 10 from a steering wheel 2. ｔｂ Along with this, a road surface reaction torque T is provided from the steering wheel 3 side. ｒｌ It is given.

[0073] Furthermore, the plant 301 receives an output shaft torque command value T via the worm gear 20. ｐ，ｃｍｄ (=N.T.) ｍ，ｃｍｄ ) is given, and friction torque T is generated by the friction between the worm wheel 21 and the worm gear 20. ｆ It is given.

[0074] If the inertia of plant 301 is J, then the equation of motion for the inertia of physical model 300 is expressed by the following equation (2).

[0075]

[0076] In equation (2), d ２ θ ｐ / dt ２ This is the angular acceleration of plant 301. N.T. ｍｃｍｄ The output shaft torque command value T ｐ，ｃｍｄ (=N.T.) ｍｃｍｄ ) is. T ｔｄ This indicates torques other than the motor torque (disturbance torque) supplied to the plant 301. In this embodiment, the disturbance torque T ｔｄ Torsion bar torque T ｔｂ and road surface reaction torque T ｒｌ and friction torque T ｆ Although it is shown as the sum of the two, in reality, the disturbance torque T ｔｄ This includes other disturbance torques besides these.

[0077] The equation of state for the physical model 400 in Figure 4 is given by the following equation (3).

[0078]

[0079] In equation (3) above, x is the state variable vector, u １ is a known input vector, u ２ is the unknown input vector, and y is the output vector (measured value). Also, in equation (3) above, A is the system matrix, B １ This is the first input matrix, B ２ is the second input matrix, C is the output matrix, and D is the direct matrix.

[0080] The aforementioned state equation is given by an unknown input vector u ２ We extend this to a system that includes as one of its states. The state equation of the extended system (extended state equation) is expressed by the following equation (4).

[0081]

[0082] In the above formula (4), x ｅ This is the state variable vector of the extended system, and Aｅ This is the system matrix of the extended system, B ｅ C is a known input matrix of the extended system. ｅ This is the output matrix of the extended system.

[0083] x ｅ , u １ and y are expressed by the following equation (5), respectively.

[0084]

[0085] From the extended state equation in equation (4) above, a disturbance observer (extended state observer) represented by the following equation (6) is constructed.

[0086]

[0087] In equation (6), ^x ｅ is, x ｅ This represents an estimate of . L is the observer gain. ^y represents an estimate of y. ^x ｅ This can be expressed by the following equation (7).

[0088]

[0089] In equation (7), ^θ ｐ is θ ｐ This is an estimate of ^T ｔｄ is T ｔｄ This is an estimated value.

[0090] The disturbance torque estimation unit 65 estimates the state variable vector value ^x based on equation (6). ｅ Perform the calculation.

[0091] Figure 5 is a block diagram showing the configuration of the disturbance torque estimation unit 65.

[0092] The disturbance torque estimation unit 65 is u １ Input section 71 and C ｅ Multiplication unit 72, first addition unit 73, L multiplication unit 74, B ｅ Multiplication unit 75 and A ｅ The multiplication unit 76, the second addition unit 77, the integration unit 78, and ^x ｅ Includes an output unit 79.

[0093] The output shaft torque command value T calculated by the disturbance torque compensation unit 67 in Figure 3.ｐ，ｃｍｄ (=N.T.) ｍｃｍｄ ) is the input vector u of equation (6) above. １ This corresponds to, u １ via input unit 71 to B ｅ This is applied to the multiplication unit 75.

[0094] The actual steering angle θ calculated by the reduction ratio division unit 52 in Figure 2 ｐ This corresponds to the output vector y (measured value) of equation (6) and is provided to the first adder 73.

[0095] The result of the integral unit 78 is the state variable vector x ｅ Estimated value of ^x ｅ (See equation (7) above) At the start of the calculation, the estimated state variable vector ^x ｅ The initial value is given as follows. State variable vector estimate ^x ｅ The initial value is, for example, 0.

[0096] A ｅ The multiplication unit 76 calculates the state variable vector estimate ^x ｅ System matrix A ｅ By multiplying by, A in equation (6) ｅ ^x ｅ Perform the calculation. C ｅ The multiplication unit 72 calculates the state variable vector estimate ^x ｅ Output matrix C ｅ By multiplying by the above formula (6), C ｅ ^x ｅ Perform the calculation.

[0097] The first adding unit 73 is the actual steering angle θ ｐ From C ｅ ^x ｅ The (y - ^y) in equation (6) is calculated by subtracting L. The L multiplication unit 74 calculates L(y - ^y) in equation (6) by multiplying (y - ^y) by the observer gain L.

[0098] B ｅ The multiplication unit 75 calculates the output shaft torque command value N・T ｍ，ｃｍｄ (=u １ ) Input matrix B ｅ By multiplying by, B in equation (6) ｅ u １The second adder 77 performs the calculation. ｅ u １ And, A ｅ ^x ｅ By adding L(y-^y), we obtain d^x from equation (6) above. ｅ Calculate / dt.

[0099] The integral part 78 is d^x ｅ By integrating / dt, the state variable vector estimate ^x is obtained. ｅ Perform the operation ^x ｅ The output unit 79 outputs the state variable vector estimate ^x ｅ Based on this, the disturbance torque estimate ^T ｔｄ , steering angle estimated value^θ ｐ and steering angular velocity estimate d^θ ｐ Outputs / dt.

[0100] In this embodiment, as can be seen from the fact that the disturbance torque estimation unit 65 includes an integration unit 78, the disturbance torque estimation unit 65 calculates the disturbance torque estimate value ^T by performing calculations including integration. ｔｄ A method for performing calculations is used.

[0101] The fault detection unit 66 will be described in detail below.

[0102] Figure 6 is a block diagram showing the configuration of the fault determination unit 66.

[0103] The fault determination unit 66 includes a first fault determination unit 81, a second fault determination unit 82, and a selector 83.

[0104] The first fault determination unit 81 determines the disturbance torque estimate value ^T. ｔｄ and motor torque command value T ｍ，ｃｍｄ and the actual steering angle θ ｐ Based on this, the disturbance torque estimation unit 65 is determined to be malfunctioning, and the first disturbance torque estimate value ^T is calculated according to the determination result. ｔｄ１ Outputs.

[0105] The second fault determination unit 82 determines the disturbance torque estimate value ^T. ｔｄ and motor torque command value T ｍ，ｃｍｄ and the actual steering angle θ ｐBased on this, it is determined whether the disturbance torque estimation unit 65 is malfunctioning, and the second disturbance torque estimate value ^T is determined according to the determination result. ｔｄ２ Outputs.

[0106] The first fault determination unit 81 and the second fault determination unit 82 have different types of faults they can determine (failure modes), and their determination methods are also different. The fault modes of the disturbance torque estimation unit 65 include "stack mode," "excess mode," "offset mode," and "vibration mode."

[0107] "Stack mode" refers to the output of the disturbance torque estimation unit 65 (disturbance torque estimate value^T). ｔｄ "Excess mode" refers to a failure mode in which the output of the disturbance torque estimation unit 65 becomes fixed at an arbitrary value. "Over-mode" refers to a failure mode in which the absolute value of the output of the disturbance torque estimation unit 65 becomes a value obtained by multiplying the original value (absolute value) by a gain greater than 1. "Offset" refers to a failure mode in which the output of the disturbance torque estimation unit 65 becomes a value obtained by adding or subtracting a certain amount from the original value. "Vibration mode" refers to a failure mode in which the output waveform of the disturbance torque estimation unit 65 becomes a vibration waveform with a relatively high frequency.

[0108] The first fault determination unit 81 primarily determines whether a "stack mode," "excess mode," or "offset mode" fault has occurred. The second fault determination unit 82 primarily determines whether a "vibration mode" fault has occurred.

[0109] First, we will explain the basic concept of the first fault determination process performed by the first fault determination unit 81.

[0110] The first fault determination unit 81 determines the disturbance torque comparison value T for fault determination in a different manner than the disturbance torque estimation unit 65. ｔｄ＿ｄｓ The first fault determination unit 81 calculates the actual steering angle θ. ｐ and motor torque command value T ｍ，ｃｍｄ Based on this, the differential equation (Jd) of equation (2) ２ θ ｐ / dt ２ = N.T. ｍ，ｃｍｄ +T ｔｄ By solving ), T ｔｄThe first fault determination unit 81 then calculates the obtained T ｔｄ The disturbance torque comparison value T ｔｄ＿ｄｓ This is set as follows. In other words, in this embodiment, the first fault determination unit 81 calculates the disturbance torque comparison value T by a calculation that does not include integral calculation. ｔｄ＿ｄｓ The following is calculated. Note that the disturbance torque comparison value T ｔｄ＿ｄｓ This may also be called the disturbance divergence value.

[0111] The first fault determination unit 81 determines the disturbance torque estimate value ^T. ｔｄ and the comparison value of disturbance torque T ｔｄ＿ｄｓ The absolute value of the difference between |T| ｔｄ＿ｄｓ -^T ｔｄ |, estimation error T ｔｄ＿ｅｒｒｏｒ The calculation is performed as follows: Estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ (T ｔｈ１ >0) The following states are referred to as "First State" or "T ｔｄ＿ｅｒｒｏｒ ≦T ｔｈ１ There are cases where it is referred to as "the state of". Also, the estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ A state greater than this is called the "second state" or "T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ The phrase "in that state" is sometimes used.

[0112] The first fault determination unit 81, under normal circumstances, uses the disturbance torque estimate value ^T calculated by the disturbance torque estimation unit 65. ｔｄ The first disturbance torque estimate^T ｔｄ１ Set it as follows.

[0113] The first fault determination unit 81 determines that the state of the disturbance torque estimation unit 65 is provisionally normal when, at a certain time tx, the state changes from the first state to the second state, and the second state continues for a time that is greater than or equal to the first predetermined time T1 and less than the second predetermined time T2 which is longer than the first predetermined time T1, from time tx. The first fault determination unit 81 then determines the disturbance torque estimate value at time tx^T ｔｄ The first disturbance torque estimate^T ｔｄ１ Set it as follows.

[0114] The first fault determination unit 81 determines that the state of the disturbance torque estimation unit 65 is abnormal (faulty) if the second state continues for a second predetermined time T2 or longer from the aforementioned time tx. The first fault determination unit 81 then determines the first disturbance torque estimate value ^T ｔｄ１ Set it to 0.

[0115] Figure 7 is a flowchart showing the procedure of the first fault determination process performed by the first fault determination unit 81. The processes in steps S1 to S10 in Figure 7 are repeatedly executed at predetermined calculation cycles until the determination result is abnormal (fault) (until a positive determination (YES) is made in step S9). In other words, the process in step S1 is started at predetermined calculation cycles until a positive determination (YES) is made in step S9.

[0116] In the first fault determination process, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ A count value C0 is used as a variable to measure the duration of the state. The initial value of the count value C0 is 0.

[0117] The first fault determination unit 81 performs estimation error calculation processing (step S1). Specifically, the first fault determination unit 81 processes the disturbance torque estimate value^T calculated by the disturbance torque estimation unit 65. ｔｄ The first fault determination unit 81 obtains the disturbance torque comparison value T for fault determination. ｔｄ＿ｄｓ The first fault determination unit 81 calculates the estimated error T. ｔｄ＿ｅｒｒｏｒ (=|T ｔｄ＿ｄｓ -^T ｔｄ Perform the operation |).

[0118] Next, the first fault determination unit 81 determines the estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ Determine whether it is greater than or equal to (Step S2).

[0119] Estimation error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If the following is true (Step S2: NO), the first fault determination unit 81 resets the count value C0 (C0 = 0) (Step S3).

[0120] Next, the first fault determination unit 81 determines that the state of the disturbance torque estimation unit 65 is normal (non-fault state), and the disturbance torque estimated value ^T obtained in step S1 is also determined. ｔｄ The first disturbance torque estimate^T ｔｄ１ The setting is configured as follows (step S4). Then, the first fault determination unit 81 terminates processing for the current calculation cycle.

[0121] In step S2, the estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If it is determined to be greater than (Step S2: YES), the first fault determination unit 81 determines whether the count value C0 is 0 or not (Step S5).

[0122] As will be explained later, the count value C0 is incremented by 1 in step S7, so the estimated error T in the previous calculation cycle ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If it is greater than or equal to, in step S5 it is determined that the count value C0 is 1 or greater, and the estimated error T in the previous calculation cycle ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If the following conditions are met, the count value C0 is determined to be 0 in step S5.

[0123] If it is determined in step S5 that the count value C0 is 0 (step S5: YES), the first fault determination unit 81 proceeds to step S6. In step S6, the first fault determination unit 81 determines the disturbance torque estimate value ^T obtained in step S1. ｔｄ The disturbance backup value T ｔｄ＿ｂａｃｋｕｐ Save as: Disturbance backup value T ｔｄ＿ｂａｃｋｕｐ This is the estimated error T. ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ From the following state, the first threshold T ｔｈ１ This is the estimated disturbance torque at the point when it becomes larger than [value]. Note that the disturbance backup value T ｔｄ＿ｂａｃｋｕｐ This is the estimated error T. ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ From the following state, the first threshold T ｔｈ１ Each time it becomes larger than this, it is updated. After this, the first fault determination unit 81 proceeds to step S7.

[0124] In step S5, if it is determined that the count value C0 is 1 or greater (step S5: NO), the first fault determination unit 81 proceeds to step S7.

[0125] In step S7, the first fault determination unit 81 increments the count value C0 by 1.

[0126] Next, the first fault determination unit 81 determines T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ Step S8 determines whether the state has continued for a first predetermined time T1 or longer. This determination is made based on whether the count value C0 is equal to or greater than a first predetermined value which corresponds to the first predetermined time T1.

[0127] T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If the condition does not persist for a first predetermined time T1 or longer (step S8: NO), the first fault determination unit 81 proceeds to step S4. The first fault determination unit 81 then terminates processing for the current calculation cycle.

[0128] In step S8, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If it is determined that the condition has continued for a first predetermined time T1 or longer (step S8: YES), the first fault determination unit 81 will, ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ Step S9 determines whether the state has continued for a second predetermined time T2 or longer than the first predetermined time T1. This determination is made based on whether the count value Co is equal to or greater than the second predetermined value, which is the count value corresponding to the second predetermined time T2.

[0129] T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If the state does not continue for a second predetermined time T2 or longer (step S9: NO), the first fault determination unit 81 determines the state of the disturbance torque estimation unit 65 as provisionally normal, and the currently held disturbance backup value T ｔｄ＿ｂａｃｋｕｐ The first disturbance torque estimate^T ｔｄ１ The setting is configured as follows (step S10). Then, the first fault determination unit 81 terminates processing for the current calculation cycle.

[0130] In step S9, Tｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If it is determined that the condition has continued for a second predetermined time T2 or longer (Step S9: YES), the first fault determination unit 81 determines that the state of the disturbance torque estimation unit 65 is abnormal (fault state), and the first disturbance torque estimate value ^T ｔｄ１ Set to 0 (step S11). Then, the first fault determination unit 81 terminates the first fault determination process. In this case, the first fault determination unit 81 continues to output an abnormality as the determination result, and the first disturbance torque estimate value ^T ｔｄ１ It continues to output 0.

[0131] The operation of the first fault determination unit 81 will be specifically explained with reference to Figures 8 and 9.

[0132] Figure 8 shows the estimated error T. ｔｄ＿ｅｒｒｏｒ , disturbance torque estimate^T ｔｄ and the estimated value of the first disturbance torque^T ｔｄ１ This is a time chart showing an example.

[0133] Figure 8A shows the estimated error T. ｔｄ＿ｅｒｒｏｒ This shows the change. In Figure 8B, the thin solid line q1, the thick dashed line q2, and the thin solid line q3 represent the disturbance torque estimates ^T. ｔｄ This shows the change. In Figure 8B, the thin solid line q1, the thick solid line q4, and the thin solid line q3 represent the estimated first disturbance torque ^T. ｔｄ１ This shows a change in the first disturbance torque estimate ^T. ｔｄ１ During the period shown by the thin solid lines q1 and q3, the disturbance torque estimate is ^T. ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It is set as such.

[0134] In the example in Figure 8, the estimated error T ｔｄ＿ｅｒｒｏｒ The first threshold T ｔｈ１ The estimated error T gradually increases from the following value at time t1. ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ It becomes larger than that. Then, the estimated error T ｔｄ＿ｅｒｒｏｒ It gradually increases for a period of time T1 or longer from time t1, and then gradually decreases. Then, at time t3, before the second predetermined time T2 has elapsed from time t1, the estimated error T ｔｄ＿ｅｒｒｏｒ The first threshold T ｔｈ１The following applies. From this point onward, the estimated error T is... ｔｄ＿ｅｒｒｏｒ The first threshold T ｔｈ１ It is changing within the following range.

[0135] At time point t1, the estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If it becomes greater than this, a positive judgment (YES) is made in steps S2 and S5, and the estimated disturbance torque at that point t1 is ^T. ｔｄ The disturbance backup value T ｔｄ＿ｂａｃｋｕｐ It is held as such. During the period up to time t1, a negative determination (NO) is made in step S2, so the state of the disturbance torque estimation unit 65 is determined to be normal, and the disturbance torque estimate value ^T ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It will be set as T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ During the period from time t1 to time t2 when the duration of this state reaches the first predetermined time T1, a negative determination (NO) is made in step S8, and the state of the disturbance torque estimation unit 65 is determined to be normal, and the disturbance torque estimate value ^T ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It will be set as follows.

[0136] At time t2, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If the state remains unchanged for a first predetermined time T1 or longer, a positive determination (YES) is made in step S8 and a negative determination (NO) is made in step S9. Therefore, the state of the disturbance torque estimation unit 65 is determined to be provisionally normal, and the disturbance backup value T held at time t1 is determined to be normal. ｔｄ＿ｂａｃｋｕｐ This is the estimated value of the first disturbance torque^T ｔｄ１ It is set as (see solid line q4).

[0137] At time t3, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ The state is the first threshold T ｔｈ１ If the following conditions are met, a negative judgment (NO) will be made in step S2, and the state of the disturbance torque estimation unit 65 will be determined to be normal, resulting in the disturbance torque estimate value ^T. ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It will be set as follows.

[0138] Figure 9 primarily shows the estimated error T.ｔｄ＿ｅｒｒｏｒ and the estimated value of the first disturbance torque^T ｔｄ１ This is a time chart showing another example.

[0139] Figure 9A shows the estimated error T. ｔｄ＿ｅｒｒｏｒ This shows the change. The thin solid line q1 and the thick dashed line q2 in Figure 9B represent the disturbance torque estimates ^T. ｔｄ This shows the change. The thin solid line q1 and the thick solid line q3 represent the first disturbance torque estimate ^T. ｔｄ１ This shows a change in the first disturbance torque estimate ^T. ｔｄ１ During the period shown by the thin solid line q1, the disturbance torque estimate ^T ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It is set as such.

[0140] In the example in Figure 9, the estimated error T ｔｄ＿ｅｒｒｏｒ The first threshold T ｔｈ１ The estimated error T gradually increases from the following value at time t1. ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ It becomes larger than t1 to T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ After maintaining this state for a second predetermined time T2 or longer, at time t4, the estimated error T ｔｄ＿ｅｒｒｏｒ The first threshold T ｔｈ１ The values ​​are as follows:

[0141] Time t2 represents the point in time after a first predetermined time T1 has elapsed from time t1, and time t3 represents the point in time after a second predetermined time T2 has elapsed from time t1. In the example in Figure 9, the estimated error T between time t1 and time t4 is ｔｄ＿ｅｒｒｏｒ It progresses through a process of gradual increase, retention at a constant value, and gradual decrease, reaching time t4.

[0142] At time point t1, the estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If it becomes greater than this, a positive judgment (YES) is made in steps S2 and S5, and the estimated disturbance torque at that point t1 is ^T. ｔｄ The disturbance backup value T ｔｄ＿ｂａｃｋｕｐ It is held as the period up to time t1 and T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１During the period from time t1 to time t2 when the duration of the state reaches the first predetermined time T1, the state of the disturbance torque estimation unit 65 is determined to be normal, and the disturbance torque estimate value ^T ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It will be set as follows.

[0143] At time t2, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ When the duration of this state reaches the first predetermined time T1, a positive determination (YES) is made in step S8 and a negative determination (NO) is made in step S9, so the state of the disturbance torque estimation unit 65 is determined to be provisionally normal, and the disturbance backup value T is set at time t1. ｔｄ＿ｂａｃｋｕｐ The disturbance torque estimate ^T is held as ｔｄ This is the estimated value of the first disturbance torque^T ｔｄ１ It will be set as follows.

[0144] At time t3, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ When the duration of this state reaches the second predetermined time T2, a positive determination (YES) is made in step S9, and the state of the disturbance torque estimation unit 65 is determined to be abnormal, and the first disturbance torque estimate value ^T ｔｄ１ 0 is set as the result. In this case, the judgment result (abnormal) and the estimated first disturbance torque ^T are determined. ｔｄ１ (=0) is maintained.

[0145] Next, we will explain the basic concept of the second fault determination process performed by the second fault determination unit 82.

[0146] The second fault determination unit 82 calculates the disturbance torque comparison value T in a different way than the disturbance torque estimation unit 65. ｔｄ＿ｄｓ The second fault determination unit 82 calculates the disturbance torque comparison value T for fault determination in the same manner as the first fault determination unit 81. ｔｄ＿ｄｓ The second fault determination unit 82 calculates the estimated error T. ｔｄ＿ｅｒｒｏｒ (=|T ｔｄ＿ｄｓ -^T ｔｄ The calculation is performed for |). Below, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ (T ｔｈ２ >0) The following states are called "Third State" or "T ｔｄ＿ｅｒｒｏｒ ≦Tｔｈ２ There are cases where it is referred to as "the state of". Also, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ A state greater than this is called the "fourth state" or "T ｔｄ＿ｅｒｒｏｒ >T ｔｈ２ The phrase "in that state" is sometimes used.

[0147] The second fault determination unit 82 normally uses the disturbance torque estimate value ^T calculated by the disturbance torque estimation unit 65. ｔｄ The second disturbance torque estimate^T ｔｄ２ The second fault determination unit 82 determines that the state of the disturbance torque estimation unit 65 is abnormal when, at a certain time tx, the state changes from the third state to the fourth state, and the third state does not continue for a third predetermined time T3 or longer, and the cumulative value of the time spent in the fourth state from time tx reaches a fourth predetermined time T4. The second fault determination unit 82 then determines the second disturbance torque estimation value^T ｔｄ２ Set to 0. Note that the fourth predetermined time T4 is set to a longer time than the third predetermined time T3.

[0148] Figure 10 is a flowchart showing the procedure of the second fault determination process performed by the second fault determination unit 82. The processes in steps S21 to S30 in Figure 10 are repeatedly executed at predetermined calculation cycles until the determination result is abnormal (fault) (until a positive determination (YES) is made in step S29). In other words, the process in step S21 is started at predetermined calculation cycles until a positive determination (YES) is made in step S29.

[0149] In the second fault determination process, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ２ A first count value C1 for measuring the cumulative time of the state, and T ｔｄ＿ｅｒｒｏｒ ≦T ｔｈ２ A second count value C2 is used as a variable to measure the duration of the state. The initial values ​​of each count value C1 and C2 are 0. The first count value C1 is the estimated error T ｔｄ＿ｅｒｒｏｒ (=|T ｔｄ＿ｄｓ -^T ｔｄ |) is the second threshold T ｔｈ２ It is incremented by 1 when it is determined to be greater than [a certain value].

[0150] The second count value C2 is a variable used to reset the first count value C1 (C1 = 0). The second count value C2 is used when the first count value C1 is 1 or greater, and the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ The value is incremented by 1 when the following conditions are met. As described later, when the second count value C2 reaches the third predetermined value CT3, which is the count value corresponding to the third predetermined time T3 [sec], the first count value C1 is reset (C1 = 0) and the second count value C2 is also reset (C2 = 0). In addition, after the first count value C1 has been incremented by 1, if it is determined that the first count value C1 is less than the fourth predetermined value CT4, which is the count value corresponding to the fourth predetermined time T4 [sec], the second count value is also reset (C2 = 0).

[0151] The second fault determination unit 82 performs an estimated error calculation process (step S21). In the estimated error calculation process, the second fault determination unit 82 calculates the disturbance torque estimate value ^T ｔｄ Acquisition of disturbance torque comparison value T ｔｄ＿ｄｓ Calculation and estimation error T ｔｄ＿ｅｒｒｏｒ (=|T ｔｄ＿ｄｓ -^T ｔｄ Perform the operation |)

[0152] Next, the second fault determination unit 82 calculates the estimated error T. ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ (T ｔｈ２ Determine whether it is greater than >0 (step S22).

[0153] Estimation error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ If the following is the case (step S22: NO), the second fault determination unit 82 determines whether the first count value C1 is 1 or greater (step S23). In other words, the second fault determination unit 82 determines whether the first count value C1 has not been reset after the increment of the first count value C1 has started.

[0154] If the first count value C1 is 0 (step S23: NO), the second fault determination unit 82 determines that the state of the disturbance torque estimation unit 65 is normal (non-fault state), and the disturbance torque estimate value ^T obtained in step S21 is also determined to be normal. ｔｄ The second disturbance torque estimate^T ｔｄ２ The setting is configured as follows (step S24). Then, the second fault determination unit 82 terminates processing for the current calculation cycle.

[0155] In step S23, if it is determined that the first count value C1 is 1 or greater (step S23: YES), the second fault determination unit 82 increments the second count value C2 by 1 (step S25).

[0156] Next, the second fault determination unit 82 determines whether the second count value C2 is greater than or equal to the third predetermined value CT3, which corresponds to the third predetermined time T3 (step S26). In other words, the second fault determination unit 82 determines whether the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ From the point in time when the following conditions occur, it is determined whether or not that condition has continued for a third predetermined time T3 or longer.

[0157] If C2 < CT3 (step S26: NO), the second fault determination unit 82 proceeds to step S24. The second fault determination unit 82 then terminates processing for the current calculation cycle.

[0158] If C2 ≥ CT3 (step S26: YES), the second fault determination unit 82 resets the first count value C1 and the second count value C2 (C1 = C2 = 0) (step S27). After the process in step S27 is completed, the second fault determination unit 82 moves on to step S24. The second fault determination unit 82 then finishes processing for the current calculation cycle.

[0159] In step S22, the estimated error T ｔｄ＿ｅｒｒｏｒ is the first threshold T ｔｈ１ If it is determined to be greater than (step S22: YES), the second fault determination unit 82 increments the first count value C1 by 1 (step S28).

[0160] Next, the second fault determination unit 82 determines whether the first count value C1 is greater than or equal to the fourth predetermined value CT4 corresponding to the fourth predetermined time T4 [sec] (step S29). In other words, the second fault determination unit 82 determines whether the estimated error T ｔｄ＿ｅｒｒｏ The second threshold T ｔｈ２ From the point when the value becomes greater than the specified value, the first count value C1 is not reset, and it is determined whether the accumulated time of that state has become greater than or equal to the fourth predetermined time T4.

[0161] If C1 < CT4 (step S29: NO), the second fault determination unit 82 resets the second count value C2 (C2 = 0) (step S30). After the processing in step S30 is completed, the second fault determination unit 82 moves on to step S24. The second fault determination unit 82 then finishes processing for the current calculation cycle.

[0162] In step S29, if it is determined that C1 ≥ CT4 (step S29: YES), the second fault determination unit 82 determines that the state of the disturbance torque estimation unit 65 is abnormal (fault state), and the second disturbance torque estimate value ^T ｔｄ２ The value is set to 0 (step S31). Then, the second fault determination unit 82 terminates the second fault determination process. In this case, the second fault determination unit 82 continues to output an abnormality as the determination result, and the second disturbance torque estimate value ^T ｔｄ２ It continues to output 0.

[0163] Referring to Figure 11, the operation of the second fault determination unit 82 will be explained in detail.

[0164] Figure 11 shows the estimated error T. ｔｄ＿ｅｒｒｏｒ , 1st count value C1, 2nd count value C2, disturbance torque estimate value ^T ｔｄ and the estimated second disturbance torque^T ｔｄ２ This is a time chart showing an example.

[0165] Figure 11A shows the estimated error T. ｔｄ＿ｅｒｒｏｒ This shows the change. Figure 11B shows the change in the first count value C1. Figure 11C shows the change in the second count value C2. In Figure 11D, the thin solid line r1 and the thick dashed line r2 represent the disturbance torque estimate ^T. ｔｄThis shows the change. The thin solid line r1 and the thick solid line r3 in Figure 11D represent the estimated second disturbance torque ^T. ｔｄ２ This shows a change in the second disturbance torque estimate ^T. ｔｄ２ During the period shown by the thin solid line r1, the disturbance torque estimate ^T ｔｄ This is the estimated value of the second disturbance torque^T ｔｄ２ It is set as such.

[0166] During the period up to time t1, a negative determination (NO) is made in step S23, so the state of the disturbance torque estimation unit 65 is determined to be normal, and the disturbance torque estimate value ^T is determined to be normal. ｔｄ This is the estimated value of the second disturbance torque^T ｔｄ２ It will be set as follows.

[0167] At time point t1, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ When it becomes larger than this, a positive judgment (YES) is made in step S22, and the increment of the first count value C1 begins.

[0168] At time point t2, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ If the following conditions are met, a negative judgment (NO) is made in step S22, and the increment of the first count value C1 is stopped. Also, a positive judgment (YES) is made in step S23, and the increment of the second count value C2 is started.

[0169] Furthermore, during the period from time t1 to time t2, the first count value C1 is less than the fourth predetermined value CT4 corresponding to the fourth predetermined time T4, so a negative determination (NO) is made in step S29. As a result, the second count value C2 is reset. Also, the state of the disturbance torque estimation unit 65 is determined to be normal, and the disturbance torque estimate value ^T ｔｄ This is the estimated value of the second disturbance torque^T ｔｄ２ It will be set as follows.

[0170] At time t3, if the second count value C2 reaches the third predetermined value CT3, which corresponds to the third predetermined time T3, a positive determination (YES) is made in step S26, and the first count value C1 and the second count value C2 are reset.

[0171] At time point t4, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ When it becomes larger than this, a positive judgment (YES) is made in step S22, and the increment of the first count value C1 begins.

[0172] At time point t5, when the first count value C1 is less than the fourth predetermined value CT4, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ If the following conditions are met, a negative judgment (NO) is made in step S22, and the increment of the first count value C1 is stopped. Also, a positive judgment (YES) is made in step S23, and the increment of the second count value C2 is started.

[0173] At time t6, when the second count value C2 is less than the third predetermined value CT3, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ When the value becomes greater than this, the increment of the first count value C1 resumes, and the second count value C2 is reset (C2 = 0).

[0174] At time point t7, when the first count value C1 is less than the fourth predetermined value CT4, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ When the following conditions are met, the increment of the first count value C1 stops, and the increment of the second count value C2 begins.

[0175] At time point t8, when the second count value C2 is less than the third predetermined value CT3, the estimated error T ｔｄ＿ｅｒｒｏｒ The second threshold T ｔｈ２ When the value exceeds a certain threshold, the increment of the first count value C1 resumes. Additionally, the second count value C2 is reset (C2 = 0).

[0176] At time point t9, if the first count value C1 reaches the fourth predetermined value CT4, a positive determination (YES) is made in step S29, and the state of the disturbance torque estimation unit 65 is determined to be abnormal, and the second disturbance torque estimate value ^T is determined to be abnormal. ｔｄ２ 0 is set as the result. In this case, the judgment result (abnormal) and the estimated second disturbance torque ^T are determined. ｔｄ２ (=0) is maintained.

[0177] Furthermore, during the period from time t2 to time t9, the first count value C1 does not reach the fourth predetermined value CT4, so the state of the disturbance torque estimation unit 65 is determined to be normal, and the disturbance torque estimate value ^T ｔｄ This is the estimated value of the second disturbance torque^T ｔｄ２ It will be set as follows.

[0178] Referring to Figure 6, the selector 83 determines the first disturbance torque estimate value ^T based on the determination result of the first fault determination unit 81 and the determination result of the second fault determination unit 82. ｔｄ１ and the estimated second disturbance torque^T ｔｄ２ Select one of the following to obtain the final disturbance torque estimate ^T ｔｄｆ Output as follows.

[0179] In this embodiment, if the determination result of the second fault determination unit 82 is normal, the selector 83 sets the first disturbance torque estimate value ^T ｔｄ１ The final disturbance torque estimate ^T ｔｄｆ It outputs as follows. On the other hand, if the determination result of the second fault determination unit 82 is abnormal and the determination result of the first fault determination unit 81 is normal or provisionally normal, the selector 83 outputs the second disturbance torque estimate value^T ｔｄ２ The final disturbance torque estimate ^T ｔｄｆ Output as follows.

[0180] In the above-described embodiment, if it is determined that the disturbance torque estimation unit 65 is malfunctioning, the disturbance torque estimate value ^T used in the disturbance torque compensation unit 67 is used. ｔｄｆ Since this can be set to 0, ADAS control can continue even when a failure in the disturbance torque estimation unit is detected in a non-redundant system.

[0181] Furthermore, in the above-described embodiment, it is possible to determine whether or not the disturbance torque estimation unit 65 is malfunctioning by a novel determination method.

[0182] While embodiments of this disclosure have been described above, this disclosure can be implemented in other forms as well.

[0183] For example, the order of steps S8 and S9 in Figure 7 may be reversed. Specifically, when the processing of step S7 is completed, the first fault determination unit 81 performs the processing of step S9. In step S9, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If it is determined that the condition has continued for a second predetermined time T2 or longer, the first fault determination unit 81 proceeds to step S11.

[0184] On the other hand, in step S9, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If it is determined that the condition has not continued for a second predetermined time T2 or longer, the first fault determination unit 81 performs the process in step S8. In step S8, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If it is determined that the condition has not continued for a first predetermined time T1 or longer, the first fault determination unit 81 proceeds to step S4.

[0185] Meanwhile, in step S8, T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If it is determined that the condition has continued for a first predetermined time T1 or longer, the first fault determination unit 81 proceeds to step S10.

[0186] Furthermore, in Figure 7, step S8 may be omitted, and if a negative determination (NO) is made in step 9, the first fault determination unit 81 may proceed to step S4. Specifically, when the processing in step S7 is completed, the first fault determination unit 81 performs the processing in step S9. If the determination in step S9 is positive (YES), the first fault determination unit 81 proceeds to step S11; if the determination in step S9 is negative (NO), the first fault determination unit 81 proceeds to step S4. In this case, the second predetermined time T2 may be set to a fifth predetermined time different from the first to fourth times.

[0187] In other words, in this case, the first fault determination unit 81 is T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１ If the condition does not continue for a fifth predetermined time or longer, the disturbance torque estimation unit 65 is determined to be in a normal state, and T ｔｄ＿ｅｒｒｏｒ >T ｔｈ１If this condition persists for a fifth predetermined time or longer, the disturbance torque estimation unit 65 is determined to be abnormal. In this case, the first fault determination unit 81 will have only two determination results: normal or abnormal, and there will be no provisional normal determination result.

[0188] The first fault determination unit 81 determines that the disturbance torque estimation unit 65 is abnormal (faulty) and calculates the first disturbance torque estimate value^T. ｔｄ１ It is set to 0. However, when the first fault determination unit 81 determines that the state of the disturbance torque estimation unit 65 is abnormal (faulty), the disturbance torque comparison value T ｔｄ＿ｄｓ The first disturbance torque estimate^T ｔｄ１ The system is set to this state and the first fault detection process continues to run. Subsequently, if the abnormal state (fault state) of the disturbance torque estimation unit 65 continues for a predetermined time or longer, the first disturbance torque estimate value ^T is calculated. ｔｄ１ You can also set it to 0.

[0189] Similarly, when the second fault determination unit 82 determines that the state of the disturbance torque estimation unit 65 is abnormal (faulty), it determines the disturbance torque comparison value T ｔｄ＿ｄｓ The second disturbance torque estimate^T ｔｄ２ The settings are configured as follows, and the first fault determination process is continued. Subsequently, if the abnormal state (fault state) of the disturbance torque estimation unit 65 continues for a predetermined time or longer, the second disturbance torque estimate value ^T is calculated. ｔｄ２ You can also set it to 0.

[0190] Furthermore, in the above-described embodiment, the fault determination unit 66 is composed of a first fault determination unit 81, a second fault determination unit 82, and a selector 83. However, the fault determination unit 66 may be composed of only the first fault determination unit 81. In that case, the first disturbance torque estimate value^T ｔｄ１ This is the final disturbance torque estimate ^T ｔｄｆ This is then supplied to the disturbance torque compensation unit 67.

[0191] Furthermore, the fault determination unit 66 may consist only of the second fault determination unit 82. In that case, the second disturbance torque estimate value^T ｔｄ２ This is the final disturbance torque estimate ^T ｔｄｆ This is then supplied to the disturbance torque compensation unit 67.

[0192] Furthermore, in the above-described embodiment, the first fault determination unit 81 and the second fault determination unit 82 determine the actual steering angle θ ｐ and motor torque command value T ｍ，ｃｍｄ Based on this, the differential equation (Jd) of equation (2) ２ θ ｐ / dt ２ = N.T. ｍ，ｃｍｄ +T ｔｄ By solving ) T ｔｄ The calculation is performed, and the resulting T ｔｄ Compared to the disturbance torque value T ｔｄ＿ｄｓ It is set as follows. However, the first fault determination unit 81 and the second fault determination unit 82 use the differential equation (Jd) of equation (2) above. ２ θ ｐ / dt ２ = N.T. ｍ，ｃｍｄ +T ｔｄ By solving ) T ｔｄ The calculation is performed, and the resulting T ｔｄ A third-order lag filter is used to perform a delay filter on the result, and the result after the delay filter is T ｔｄ Compared to the disturbance torque value T ｔｄ＿ｄｓ You can set it as such.

[0193] While embodiments of this disclosure have been described in detail, these are merely examples used to illustrate the technical content of this disclosure, and this disclosure should not be construed as being limited to these examples. The scope of this disclosure is limited only to the attached claims.

[0194] 18...Electric motor, 53...Manual steering angle command value generation unit, 54...Integrated angle command value calculation unit, 55...Angle control unit, 56...Torque control unit, 57...Assist torque command value setting unit, 58...Manual steering angle command value setting unit, 61...Low-pass filter, 62...Feedback control unit, 63...Feedforward control unit, 64...Torque addition unit, 65...Disturbance torque estimation unit, 66...Fault determination unit, 67...Disturbance torque compensation unit, 71...First fault determination unit, 72...Second fault determination unit, 73...Selector.

Claims

1. A motor control device for driving and controlling an electric motor for steering angle control, comprising: a manual steering angle command value generation unit that generates a manual steering angle command value using steering torque; an integrated angle command value calculation unit that calculates an integrated angle command value by adding the manual steering angle command value to an automatic steering angle command value; and a control unit that controls the electric motor based on the integrated angle command value, wherein the control unit comprises: a basic torque command value calculation unit that calculates a basic torque command value based on the integrated angle command value; a disturbance torque estimation unit for calculating a disturbance torque estimate value which is an estimated value of torque other than motor torque applied to the target of the electric motor's drive; a disturbance torque compensation unit that basically corrects the basic torque command value using the disturbance torque estimate value and outputs a compensated torque command value; and a failure determination unit that determines whether the disturbance torque estimation unit is malfunctioning and, when it is determined that the disturbance torque estimation unit is malfunctioning, sets the disturbance torque estimate value used in the disturbance torque compensation unit to zero.

2. The motor control device according to claim 1, wherein the fault determination unit calculates a disturbance torque comparison value by a method different from that of the disturbance torque estimation unit, and determines whether or not the disturbance torque estimation unit is faulty based on the estimation error, which is the absolute value of the difference between the disturbance torque estimation value and the disturbance torque comparison value.

3. The motor control device according to claim 2, wherein the disturbance torque estimation unit calculates the disturbance torque estimate value by an operation including an integral operation, and the fault determination unit calculates the disturbance torque comparison value by an operation that does not include an integral operation.

4. The motor control device according to claim 3, wherein the fault determination unit is configured to set the disturbance torque comparison value as the disturbance torque estimate value used in the disturbance torque compensation unit when it determines that the disturbance torque estimation unit is faulty, and thereafter, when the faulty state of the disturbance torque estimation unit continues for a predetermined time or longer, it sets the disturbance torque estimate value used in the disturbance torque compensation unit to zero.

5. A motor control device according to claim 2 or 3, wherein the state in which the estimation error is less than or equal to a first threshold is defined as a first state, and the state in which the estimation error is greater than the first threshold is defined as a second state, the fault determination unit sets the estimated disturbance torque at that time as the estimated disturbance torque used in the disturbance torque compensation unit when the state changes from the first state to the second state at a certain point in time, and the second state continues for a time of a first predetermined time or more and longer than the first predetermined time but less than a second predetermined time, and sets the estimated disturbance torque used in the disturbance torque compensation unit to zero when the second state continues for a second predetermined time or more.

6. A motor control device according to claim 2 or 3, wherein the state in which the estimation error is less than or equal to a second threshold is defined as a third state, and the state in which the estimation error is greater than the second threshold is defined as a fourth state, the fault determination unit sets the disturbance torque estimate value used in the disturbance torque compensation unit to zero when, at a certain point in time, the third state changes to the fourth state, and the third state does not continue for more than a third predetermined time, and the cumulative value of the time in the fourth state from that point in time reaches a fourth predetermined time that is longer than the third predetermined time.

7. A motor control device according to claim 2 or 3, wherein the state in which the estimation error is less than or equal to a first threshold is defined as a first state, and the state in which the estimation error is greater than the first threshold is defined as a second state, and the fault determination unit sets the disturbance torque estimate value used in the disturbance torque compensation unit to zero when the state changes from the first state to the second state at a certain point in time, and the second state continues for a fifth predetermined time from that point in time.

Images