Autonomous driving assistance device

Abstract

The present application provides an automatic driving assistance device that can continue automatic steering when an abnormality is detected in a control system of a steering motor, such as a drive circuit of the steering motor and a control device of the steering motor. The automatic driving assistance device (1) includes: an automatic steering control section (120) that calculates a steering angle command value of a steering device of a host vehicle based on a detected running state and a detected surrounding state; a steering motor (5); a motor drive circuit (30); a steering angle control section (130) that calculates a motor output command value based on the steering angle command value and a detected steering angle value; a motor control section (150) that generates a drive signal of the motor drive circuit based on the motor output command value; and an abnormality detection section (160) that the motor control section (150) generates a drive signal at the time of an abnormality corresponding to a content of an abnormality related to the steering motor.

Description

Technical Field

[0001] This application relates to autonomous driving assistance devices. Background Technology

[0002] As an example of a technology that handles abnormalities in driving assistance by changing the control, there is a technology like Patent Document 1. In the technology of Patent Document 1, when an abnormality is detected in the current indication value of the steering motor of the electric power steering system, a current indication value that causes the counter current to flow in the opposite direction to the current indication value is calculated based on the yaw rate of the vehicle, thereby suppressing the movement of the vehicle's rotational direction and preventing instability in the vehicle's behavior.

[0003] Furthermore, as another example of a technology for handling abnormalities in driver assistance, there is a technology like that in Patent Document 2. In the technology of Patent Document 2, when the first sensor malfunctions, a second sensor is used to continue driver assistance. Alternatively, when the first yaw rate sensor malfunctions, the yaw rate is estimated based on the steering angle and vehicle speed, and a target steering angle, i.e., the steering angle command value, is determined based on the estimated yaw acceleration to perform target trajectory tracking control. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-014432 Patent Document 2: Japanese Patent Application Publication No. 2018-192865 Summary of the Invention The technical problem that the invention aims to solve

[0005] However, while the technology in Patent Document 1 can handle abnormalities in the current indication value, it suffers from the following problem: it cannot handle abnormalities in the control system of the steering motor, such as the drive circuit and control device that control the current flowing through the steering motor based on the current indication value. Furthermore, it does not determine which structural element related to the generation of the current indication value is causing the abnormality; instead, it simply calculates the current indication value flowing through the counter current that suppresses yaw acceleration. Therefore, it lacks control suitable for abnormal states. While it can prevent vehicle behavior from becoming unstable, it also prevents the continued operation of driving assistance that follows the target driving trajectory.

[0006] In Patent Document 2, a second sensor is used when the first sensor malfunctions. However, this redundancy increases costs. Furthermore, while the yaw rate can be estimated, if an anomaly occurs outside the yaw rate sensor, driving assistance cannot continue. In particular, there is a problem that anomalies in the control system of the aforementioned steering motor cannot be handled.

[0007] Therefore, the purpose of this application is to provide an automatic driving assistance device that enables automatic steering to continue when an abnormality is detected in the control system of the steering motor, such as the drive circuit and control device of the steering motor. Technical means for solving technical problems

[0008] The autonomous driving assistance devices involved in this application include: An automatic steering control unit detects the driving status of the vehicle and the surrounding environment of the vehicle, and calculates the steering angle command value of the vehicle's steering device based on the detected driving status and surrounding environment. A steering motor that drives the steering device; An electric motor drive circuit having a switching element to turn the power supplied to the steering motor on and off; A steering angle control unit calculates a motor output command value related to the output torque of the steering motor based on the steering angle command value and the steering angle detection value; and A motor control unit, which generates drive signals to turn the switching elements of the motor drive circuit on and off based on the motor output command value; and The anomaly detection unit detects anomalies generated by the control system of the steering motor, i.e., steering motor-related anomalies. When an abnormality related to the steering motor is detected, the motor control unit generates a drive signal corresponding to the content of the abnormality based on the motor output command value. Invention Effects

[0009] According to the automated driving assistance device of this application, even in the event of an abnormality related to the steering motor, a drive signal for the abnormality can be generated, and the steering device can continue to be driven by the steering motor to ensure that automatic steering continues. By continuing automatic steering, the driver can feel safer. No additional hardware is needed specifically for abnormal situations; only the processing of the drive signal for abnormal situations is required, thus suppressing cost increases. Attached Figure Description

[0010] Figure 1 This is a simplified structural diagram of the autonomous driving assistance device according to Embodiment 1. Figure 2 This is a simplified block diagram of the autonomous driving assistance device according to Embodiment 1. Figure 3 This is a diagram summarizing the processing of anomaly detection for each sensor involved in Implementation Method 1. Figure 4 This is a circuit diagram of the motor drive circuit involved in Implementation Method 1. Figure 5 This is a hardware structure diagram of the control device involved in Implementation Method 1. Figure 6 This is a block diagram of the automatic steering control unit under normal conditions according to Embodiment 1. Figure 7 This is a block diagram of the steering angle control unit under normal conditions according to Embodiment 1. Figure 8 This is a block diagram of the motor control unit under normal conditions according to Embodiment 1. Figure 9 This is a block diagram of the motor control unit when an open-circuit abnormality of one phase is detected, as described in Embodiment 1. Figure 10 This is a block diagram of the steering angle control unit when an abnormality in phase 1 is detected, as described in Embodiment 1. Figure 11 This diagram illustrates the correction of the steering angle command value to avoid outputting a reduced steering angle when an abnormality occurs in Phase 1, as described in Implementation 1. Figure 12 This is a block diagram of the motor control unit when a short-circuit anomaly in one phase is detected, as described in Embodiment 1. Figure 13 This is a block diagram of the motor control unit when an abnormality is detected in the current sensor, as described in Embodiment 1. Figure 14 This is a block diagram of the steering angle motor control unit when an abnormality is detected in the current sensor, as described in Embodiment 1. Figure 15 This is a block diagram of the motor control unit when an abnormality is detected in the rotation angle sensor according to Embodiment 1. Figure 16 This is a block diagram of the rotation estimation unit of the motor control unit when an abnormality is detected in the rotation angle sensor according to Embodiment 1. Figure 17 This is a block diagram of the rotation estimation unit of the motor control unit when an abnormality of the rotation angle sensor is detected, as described in Embodiment 1. Figure 18 This is a block diagram of the automatic steering control unit that detects an abnormality in the steering angle detection value according to Embodiment 1. Figure 19 This is a block diagram of the steering angle control unit when an abnormality in the steering angle detection value is detected, as described in Embodiment 1. Figure 20 This is a simplified structural diagram of the autonomous driving assistance device according to Embodiment 2. Figure 21This is a simplified block diagram of the autonomous driving assistance device according to Embodiment 2. Figure 22 This is a diagram summarizing the processing of anomaly detection for each sensor involved in Implementation Method 2. Figure 23 This is a block diagram of the steering angle control unit under normal conditions according to Embodiment 2. Figure 24 This is a block diagram of the steering angle control unit when an abnormality is detected in the steering angle sensor, as described in Embodiment 2. Figure 25 This is a diagram summarizing the processing of anomaly detection for each sensor involved in Implementation Method 3. Figure 26 This is a block diagram of the steering angle control unit under normal conditions according to Embodiment 3. Figure 27 This is a block diagram of the steering angle control unit when an abnormality is detected in the rotation angle sensor, as described in Embodiment 3. Figure 28 This is a simplified structural diagram of the autonomous driving assistance device according to Embodiment 4. Figure 29 This is a simplified block diagram of the autonomous driving assistance device according to Embodiment 4. Figure 30 This is a diagram summarizing the processing of anomaly detection for each sensor involved in Implementation Method 4. Figure 31 This is a circuit diagram of the motor drive circuit involved in Implementation Method 4. Figure 32 This is a block diagram of the motor control unit under normal conditions according to Embodiment 4. Figure 33 This is a block diagram of the motor control unit when an abnormality is detected in the current sensor, as described in Embodiment 4. Figure 34 This is a block diagram of the motor control unit when an abnormality is detected in the steering angle sensor, as described in Embodiment 4. Figure 35 This is a block diagram of the steering angle control unit when an abnormality is detected in the steering angle sensor, as described in Embodiment 4. Figure 36 This is a graph illustrating the relationship between the estimated value of the impedance and the rotation angle involved in Embodiment 4. Figure 37 This is a simplified structural diagram of the autonomous driving assistance device according to Embodiment 5. Figure 38 This is a simplified block diagram of the autonomous driving assistance device according to Embodiment 5. Figure 39 This is a diagram summarizing the processing of anomaly detection for each sensor involved in Implementation Method 5. Detailed Implementation

[0011] 1. Implementation Method 1 The autonomous driving assistance device 1 according to Embodiment 1 will be described with reference to the accompanying drawings. The autonomous driving assistance device 1 is mounted on a vehicle. Figure 1 The diagram shows a simplified structural diagram of the autonomous driving assistance device 1. Figure 2 A simplified block diagram of the autonomous driving assistance device 1 is shown in the figure. Figure 3 The diagram below summarizes the processing steps for anomaly detection by each sensor.

[0012] 1-1. Basic Structure of Automated Driving Assistance Device 1 The automatic driving assistance device 1 includes a steering motor 5, a motor drive circuit 30, a control device 100, a surrounding monitoring device 20, a driving status detection device 21, a position detection device 22, and a wireless communication device 23.

[0013] The surrounding monitoring device 20 is a device for detecting the surrounding conditions of the vehicle. The signal from the surrounding monitoring device 20 is input to the control device 100. For example, the surrounding monitoring device 20 may be a camera, radar, or other device that monitors the surroundings of the vehicle. The radar may be millimeter-wave radar, lidar, ultrasonic radar, etc.

[0014] The driving state detection device 21 is a device for detecting the driving state of the vehicle. The driving state detection device 21 detects the vehicle speed, roll rate, pitch rate, yaw rate, acceleration in the longitudinal direction, acceleration in the vertical direction, and lateral acceleration of the vehicle to determine its driving state. For example, the driving state detection device 21 may include a three-axis angular velocity sensor that detects the roll rate, pitch rate, and yaw rate acting on the vehicle; a three-axis acceleration sensor that detects the acceleration in the longitudinal direction, acceleration in the vertical direction, and lateral acceleration; and a speed sensor that detects the rotational speed of the wheels. In this embodiment, it is sufficient to configure it to detect at least the vehicle speed, yaw rate, and lateral acceleration.

[0015] The position detection device 22 is used to detect the current position (latitude, longitude, and altitude) of the vehicle, and employs a GPS antenna or similar device to receive signals from artificial satellites such as GNSS (Global Navigation Satellite System). The wireless communication device 23 uses cellular wireless communication standards such as 4G and 5G to communicate wirelessly with a base station.

[0016] The automatic driving assistance device 1 constitutes an electric power steering system. The steering motor 5 is the motor that drives the steering mechanism 8, which in turn drives the wheels 7. The rotation shaft of the steering motor 5 is connected to the steering mechanism 8 via a gear mechanism. The steering mechanism 8 is a mechanism that changes the steering angle of the wheels 7. The steering angle of the wheels 7 changes as the steering motor 5 rotates. That is, the rotation angle of the steering motor 5 and the steering angle have a proportional relationship multiplied by a predetermined conversion ratio.

[0017] In this embodiment, the steering device 8 includes a rack and pinion 6. The rack and pinion 6 converts the rotational motion of the steering shaft 4 into linear motion in the left and right directions, driving the connecting rod and steering knuckle arm, and changing the steering angle of the wheels 7. The steering shaft 4 is connected to the steering wheel 2. The steering shaft 4 is equipped with a torque sensor 3, which detects the steering torque exerted by the driver on the steering wheel 2.

[0018] The rotating shaft of the steering motor 5 is connected to the steering shaft 4 via a gear mechanism such as a worm gear mechanism. The rotation of the steering motor 5 is converted by the gear ratio of the gear mechanism and transmitted to the steering shaft 4. In addition, the steering motor 5 can be connected to the rack and pinion 6 via a gear mechanism.

[0019] like Figure 4 As shown, the steering motor 5 is an AC motor with three-phase (U-phase, V-phase, W-phase) armature windings Cu, Cv, and Cw. The three-phase armature windings Cu, Cv, and Cw are wound onto the stator 3, and the rotor is equipped with permanent magnets. The steering motor 5 is a permanent magnet type synchronous motor. The rotor's rotation shaft is connected to the steering device 8 via a gear mechanism. It can be a synchronous motor with an excitation winding on the rotor, or an induction motor with a squirrel-cage conductor on the rotor. Furthermore, it can also have three or more armature windings.

[0020] The motor drive circuit 30 has switching elements for turning the power supplied to the steering motor 5 on and off. In this embodiment, the motor drive circuit 30 has switching elements for each phase that turn the armature winding on and off when a voltage is applied to it. Specifically, the motor drive circuit 30 has a series circuit for each phase, which is formed by connecting a high-potential side switching element Sp connected to the high-potential side of the DC power supply 34 and a low-potential side switching element Sn connected to the low-potential side of the DC power supply 34 in series. The connection point of the two switching elements in the series circuit of each phase is connected to the armature winding of the corresponding phase.

[0021] A current sensor 31 is provided to detect the current flowing through the steering motor 5. In this embodiment, the current sensor 31 is provided in the series circuit of the two switching elements of each phase. Alternatively, the current sensor 31 can be provided on the wire connecting the series circuit of the two switching elements of each phase and the armature winding of each phase. Or, the current sensor 31 can be provided on the wire connecting the motor drive circuit 30 and the DC power supply 34, and the current of the armature winding of each phase can be detected using the known "bus 1 shunt method".

[0022] A rotation angle sensor 32 is provided, which is used to detect the rotation angle of the rotor. The rotation angle sensor 32 uses a rotary transformer, encoder, MR sensor, etc.

[0023] 1-2. Control device The control device 100 includes functional units such as a steering method determination unit 110, an automatic steering control unit 120, a steering angle control unit 130, a steering assist control unit 140, a motor control unit 150, and an anomaly detection unit 160. Each function of the control device 100 is implemented by its processing circuitry. The control device 100 can be composed of multiple control devices that communicate with each other.

[0024] For example, such as Figure 5As shown, the control device 100 includes an arithmetic processing unit 90 such as a CPU (Central Processing Unit), a storage device 91, and an input / output device 92 for inputting and outputting external signals to the arithmetic processing unit 90. The arithmetic processing unit 90 may include ASIC (Application Specific Integrated Circuit), IC (Integrated Circuit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), GPU (Graphics Processing Unit), AI (Artificial Intelligence) chip, various logic circuits, and various signal processing circuits. Furthermore, the arithmetic processing unit 90 may also include multiple arithmetic processing units of the same or different types to share the execution of various processes. As a storage device 91, various storage devices such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), and hard disk drive are used.

[0025] The input / output device 92 includes a communication device, an A / D converter, input / output ports, and a drive circuit. The input / output device 92 is connected to the torque sensor 3, the peripheral monitoring device 20, the driving status detection device 21, the position detection device 22, the wireless communication device 23, the motor drive circuit 30, the current sensor 31, and the rotation angle sensor 32, and transmits signals with these devices.

[0026] The functions of each functional unit 110 to 160 of the control device 100 are implemented by the arithmetic processing unit 90 executing software (programs) stored in the storage device 91, and in cooperation with other hardware of the control device 100 such as the storage device 91 and the input / output device 92. In addition, the setting data such as the judgment values ​​and thresholds used by each functional unit 110 to 160 are stored as part of the software (programs) in the storage device 91 such as ROM.

[0027] 1-2-1. Structure of the steering method determination unit under normal conditions The steering method determination unit 110 determines whether automatic steering or driver steering assistance should be performed by the automatic steering control unit 120 and the steering angle control unit 130. In this embodiment, the steering method determination unit 110 determines whether to perform automatic steering or steering assistance based on the detected value of the steering torque of the driver's steering wheel. The steering method determination unit 110 uses the torque sensor 3 to detect the steering torque. The steering method determination unit 110 determines whether to perform automatic steering or steering assistance based on driver commands via the human-machine interface, as an initial determination. If the absolute value of the steering torque exceeds a predetermined determination value during the execution of automatic steering and this condition persists for the determination period, the steering method determination unit 110 determines that steering assistance should be performed.

[0028] 1-2-2. Structure of the automatic steering control unit under normal conditions When it is determined that automatic steering is to be performed, the automatic steering control unit 120 detects the driving status of the vehicle and the surrounding conditions of the vehicle, and calculates the steering angle command value of the vehicle's steering device 8 based on the detected driving status and surrounding conditions.

[0029] like Figure 6 As shown, the automatic steering control unit 120 includes a surrounding condition acquisition unit 121, a driving state acquisition unit 122, a target track following control unit 123, a lane departure suppression control unit 124, and a steering angle command value selection unit 125.

[0030] The surrounding conditions acquisition unit 121 detects the surrounding conditions of the vehicle. Based on detection information of dividing lines such as white lines and shoulders obtained from the surrounding monitoring device 20, the surrounding conditions acquisition unit 121 detects road shapes, including road dividing lines. Furthermore, based on the detection information obtained from the surrounding monitoring device 20, the surrounding conditions acquisition unit 121 detects other vehicles, obstacles, pedestrians, etc., existing around the vehicle. Additionally, based on the vehicle's position information obtained from the position detection device 22, the surrounding conditions acquisition unit 121 obtains road information about the vehicle's surroundings from a map information database stored in the storage device 91 or a map information database on an external server.

[0031] The driving state acquisition unit 122 detects the driving state of the vehicle. The driving state acquisition unit 122 acquires the vehicle speed, roll rate, pitch rate, yaw rate, and accelerations in the longitudinal, vertical, and lateral directions from the driving state detection device 21 as the vehicle's driving state. The driving state acquisition unit 122 can be configured to detect at least the vehicle speed, yaw rate, and lateral acceleration. Furthermore, the driving state acquisition unit 122 acquires the vehicle's position and direction of movement based on the vehicle's position information acquired from the position detection device 22. Additionally, the driving state acquisition unit 122 acquires information about the vehicle's position relative to the lane based on the shape of the lane acquired from the surrounding conditions acquisition unit 121.

[0032] When the steering method determination unit 110 determines that target trajectory following control should be executed, the target trajectory following control unit 123 generates a target travel trajectory that matches the surrounding conditions (e.g., other vehicles, obstacles, road shape) detected by the surrounding condition acquisition unit 121. The target travel trajectory is a travel trajectory composed of the vehicle's position, direction of travel, and speed at future times. Various known methods are used to generate the target travel trajectory. Target travel trajectories include various types such as target travel trajectories along a path to the destination, target travel trajectories for lane changes, and target travel trajectories for obstacle avoidance.

[0033] The target track following control unit 123 calculates the steering angle command value for the vehicle to follow the target track based on the target travel track, the vehicle's travel state, and the vehicle's surrounding conditions. The target track following control unit 123 calculates the steering angle command value based on the vehicle's lateral position relative to the target travel track, the vehicle's tilt in the longitudinal direction relative to the extension direction of the target travel track, the vehicle speed, yaw rate, and lateral acceleration. Various known methods are used in calculating the steering angle command value for following the target travel track.

[0034] When the steering method determination unit 110 determines that lane departure suppression control should be executed, the lane departure suppression control unit 124 calculates a steering angle command value to maintain the vehicle from deviating from its lane based on the vehicle's driving state and surrounding conditions. The lane departure suppression control unit 124 calculates the steering angle command value based on the vehicle's lateral position relative to its lane, the vehicle's tilt in the longitudinal direction relative to the lane's extension direction, vehicle speed, yaw rate, and lateral acceleration. Various known methods are used in calculating the steering angle command value for following the lane.

[0035] When it is determined that target track following control is to be executed, the steering angle command value selection unit 125 selects the steering angle command value calculated by the target track following control unit 123 and transmits it to the motor control unit 150. When it is determined that lane departure suppression control is to be executed, the steering angle command value selection unit 125 selects the steering angle command value calculated by the lane departure suppression control unit 124 and transmits it to the motor control unit 150.

[0036] 1-2-3. Structure of the steering angle control unit under normal conditions The steering angle control unit 130 calculates the motor output command value related to the output torque of the steering motor 5 based on the steering angle command value and the steering angle detection value. For example... Figure 7 As shown, the steering angle control unit 130 includes an output command calculation unit 131 and a steering angle detection unit 132. In this embodiment, the steering angle detection unit 132 detects the steering angle based on the cumulative value of the rotation angle of the steering motor. Specifically, the steering angle detection unit 132 calculates the steering angle detection value by multiplying the cumulative value of the rotation angle by a conversion coefficient preset according to the gear ratio. The cumulative value of the rotation angle when the steering angle is 0 is set to 0. Here, the cumulative value of the rotation angle is the angle obtained by accumulating the rotation angle without resetting it to 0 for each rotation, except when the steering angle is 0.

[0037] The output command calculation unit 131 uses feedback control, such as PI control based on the deviation between the steering angle command value and the steering angle detection value, to change the motor output command value. Alternatively, various known control methods can be used. In this embodiment, the output command calculation unit 131 calculates the q-axis current command value as the motor output command value. The output command calculation unit 131 can also calculate the torque command value as the motor output command value.

[0038] 1-2-4. Structure of the steering assist control unit under normal conditions When steering assist is required, the steering assist control unit 140 calculates the motor output command value based on the detected steering torque, replacing the automatic steering control unit 120 and the steering angle control unit 130. For example, the steering assist control unit 140 calculates the motor output command value by multiplying the detected steering torque by a conversion factor. In this embodiment, the torque assist control unit 140 calculates the q-axis current command value as the motor output command value. The steering assist control unit 140 may also calculate the torque command value as the motor output command value.

[0039] 1-2-5. Structure of the motor control unit under normal conditions The motor control unit 150 generates drive signals that turn the switching elements of the motor drive circuit 30 on and off based on the motor output command value. For example... Figure 8 As shown, the motor control unit 150 under normal conditions includes a rotation detection unit 151, a current detection unit 152, a current command setting unit 153, a current feedback control unit 154, a voltage command coordinate conversion unit 155, and a PWM control unit 156.

[0040] The current feedback control unit 154 performs current feedback control to change the voltage command value applied to the armature winding, so that the current detection value flowing through the armature winding is close to the current command value set according to the motor output command value. The current feedback control unit 154 performs vector control to change the voltage command value, so that the current detection value in the dq-axis rotating coordinate system is close to the current command value. The d-axis is determined in the direction of the rotor's magnetic pole (N pole, magnetic pole position), and the q-axis is determined in the direction where the electrical angle is 90° ahead of the d-axis.

[0041] The current command setting unit 153 sets the current command values ​​for the d-axis and q-axis based on the motor output command value. In this embodiment, the q-axis current command value is transmitted from the steering angle control unit 130 as the motor output command value. Therefore, the current command setting unit 153 sets the current command value for the d-axis to make the rotor flux appropriate. Furthermore, when the torque command value is transmitted from the steering angle control unit 130 as the motor output command value, the current command setting unit 153 sets the current command values ​​for the d-axis and q-axis based on the torque command value, rotational angular velocity, and power supply voltage using various known vector control methods such as maximum torque current control, field weakening control, and Id=0 control.

[0042] The rotation detection unit 151 detects the rotation angle (magnetic pole position) and rotational angular velocity of the rotor's electrical angle based on the output signal of the rotation angle sensor 32. The current detection unit 152 detects the current flowing through the armature winding of each phase based on the output signal of the current sensor 31. The current detection unit 152 performs three-phase two-phase conversion and rotation coordinate conversion on the current detection values ​​of the three phases based on the rotation angle (magnetic pole position), and converts them into d-axis current detection values ​​and q-axis current detection values. Then, the current feedback control unit 154 performs current feedback control by changing the d-axis voltage command value and q-axis voltage command value through PI control or the like, so that the d-axis current detection value and q-axis current detection value are close to the d-axis current command value and q-axis current command value.

[0043] The voltage command value coordinate transformation unit 155 performs fixed coordinate transformation and two-phase / three-phase transformation on the d-axis and q-axis voltage command values ​​based on the rotation angle (magnetic pole position), and converts them into three-phase voltage command values. The PWM control unit 156 generates drive signals that turn on and off each switching element of the motor drive circuit 30 based on the three-phase voltage command values ​​through PWM (Pulse Width Modulation) control. In the PWM control, known carrier comparison PWM or space vector PWM is used.

[0044] 1-2-6. Structure of the Anomaly Detection Unit The anomaly detection unit 160 detects various anomalies in the automatic driving assistance device. In this embodiment, the anomaly detection unit 160 detects anomalies generated by the control system of the steering motor, i.e., steering motor-related anomalies. There are various types of steering motor-related anomalies, which will be described below.

[0045] <Detection of Circuit Abnormalities in Phase 1> The fault detection unit 160 detects any circuit fault in any one phase as a fault related to the steering motor. As explained below, a circuit fault in one phase can be either an open circuit fault or a short circuit fault.

[0046] In the motor drive circuit 30, if an open-circuit fault occurs in any phase's switching element, or if the current supply path for any phase is interrupted, current cannot be normally supplied to the armature winding of the phase with the open-circuit fault. Various known methods are used for detecting open-circuit faults and determining the faulty phase. For example, if the period during which the current detection value of any phase remains at 0 is longer than the judgment period, the anomaly detection unit 160 determines that an open-circuit fault has occurred in that phase. Alternatively, the anomaly detection unit 160 can determine an open-circuit fault based on the current detection value when the drive signal for anomaly determination is output to the motor drive circuit 30, and the potential difference between the high-potential side and the low-potential side of each switching element.

[0047] In the motor drive circuit 30, if a short-circuit fault occurs in any phase's switching element, or if a short circuit occurs in any phase's current supply path to the high-potential side or low-potential side of the DC power supply 34, current cannot be normally supplied to the armature winding of the phase experiencing the short-circuit fault. The short-circuit fault detection method and the faulty phase determination method use various known methods. For example, if the current detection value of any phase remains above a threshold for a period exceeding the determination period, and the current detection values ​​of other phases remain below the threshold for a period exceeding the determination period, the anomaly detection unit 160 determines that a short-circuit fault has occurred in that phase. Alternatively, the anomaly detection unit 160 can determine a short-circuit anomaly based on the current detection value when the drive signal for anomaly determination is output to the motor drive circuit 30, and the potential difference between the high-potential side and the low-potential side of each switching element.

[0048] <Anomaly Detection of Current Sensors> The anomaly detection unit 160 detects an anomaly in the current sensor 31 as a related anomaly to the steering motor, wherein the current sensor 31 detects the current supplied to the steering motor (armature winding in this example). Various known methods are used to detect a fault in the current sensor 31. For example, the anomaly detection unit 160 determines an anomaly in the current sensor 31 based on the current detection value when an anomaly determination drive signal is output to the motor drive circuit 30. In the case where a current sensor 31 is provided that detects the current of each of the three phases, anomalies in the current sensors of each phase are detected.

[0049] <Anomaly Detection of Rotation Angle Sensor> The anomaly detection unit 160 detects an anomaly in the rotation angle sensor 32, which detects the rotation angle of the steering motor, as a steering motor-related anomaly. Various known methods are used to detect the fault in the rotation angle sensor 32.

[0050] 1-2-7. Control when a steering motor-related abnormality is detected When an anomaly is detected in the control system of the steering motor, i.e., a steering motor-related anomaly, the motor control unit 150 generates a drive signal corresponding to the content of the steering motor-related anomaly based on the motor output command value. According to this structure, even in the event of a steering motor-related anomaly, a drive signal can be generated to continue driving the steering device 8 via the steering motor, thereby enabling automatic steering or steering assistance to continue.

[0051] 1-2-7-1. Control when a circuit abnormality is detected in one phase As a fault related to the steering motor, when a circuit fault is detected in any one phase, the motor control unit 150 generates a drive signal based on the motor output command value to turn the switching elements of the remaining normal phases on and off. According to this structure, even when a circuit fault is detected in one phase, by turning the switching elements of the remaining normal phases on and off, the steering motor can continue to drive the steering device 8, and automatic steering or steering assist can continue.

[0052] <When an open circuit anomaly is detected in one phase> In the event of an open-circuit anomaly detected in one phase, for example, the method disclosed in Japanese Patent No. 4498353 can be used. Specifically, if compared with the method in Japanese Patent No. 4498353... Figure 3 If the method is similarly configured, then the motor control unit 150 is as follows: Figure 9As shown, it includes a target phase current shaping unit 151B, a deviation calculation unit 152B, and an abnormal current control unit 153B. The target phase current shaping unit 151B converts the q-axis current command value into the normal current command values ​​for each of the two phases based on the rotation angle θ. Figure 9 The diagram illustrates a situation where phase U is abnormal, while phases V and W are normal. Then, the deviation calculation unit 152B calculates the deviation between the current command value and the current detection value for each of the two normal phases. In the abnormal situation, the current control unit 153B calculates the voltage command value for each of the two normal phases based on the current deviation using feedback control such as PI control, and generates drive signals to turn on and off the switching elements of each of the two normal phases using PWM control based on the voltage command values ​​of each of the two normal phases. In the abnormal situation, the current control unit 153B generates drive signals that keep the switching elements of the abnormal phase always off.

[0053] For example, Japanese Patent No. 4498353 Figure 5 and Figure 10 As shown, at a specific rotation angle corresponding to the abnormal phase, the current cannot flow through the armature winding of the abnormal phase, nor can it flow through the armature winding of the normal two phases. Therefore, the steering motor 5 cannot output torque, and the output torque drops to 0.

[0054] When the U-phase is abnormal, the output torque drops to 0 when the rotation angle θ is an electrical angle of 90 degrees or 270 degrees. When the V-phase is abnormal, the output torque drops to 0 when the rotation angle θ is an electrical angle of 30 degrees or 210 degrees. When the W-phase is abnormal, the output torque drops to 0 when the rotation angle θ is an electrical angle of 150 degrees or 330 degrees.

[0055] like Figure 10 As shown, the steering angle control unit 130 includes a steering angle command correction unit 133. The steering angle command value correction unit 133 corrects the steering angle command value so that when an open-circuit fault is detected in any one phase, the output torque is prevented from decreasing by the steering angle corresponding to the rotation angle of the steering motor that causes the fault. Then, the output command calculation unit 131 calculates the motor output command value at the time of the fault based on the corrected steering angle command value and the detected steering angle value.

[0056] According to this structure, the steering angle is controlled to avoid a decrease in the output torque of the steering motor. Therefore, the situation of stopping at the rotation angle where the output torque decreases is suppressed. Even if a circuit abnormality in any one phase is detected, the steering motor can still output torque and continue automatic steering or steering assistance.

[0057] As described above, the cumulative value of the rotation angle multiplied by the conversion coefficient corresponding to the gear ratio is the steering angle. As mentioned above, when an open-circuit fault occurs in one phase, the relationship between the faulty phase and the rotation angle θ that causes the output torque to decrease is known; therefore, the relationship between the faulty phase and the output torque decrease steering angle can also be determined. Therefore, the steering angle command value correction unit 133 sets the output torque decrease steering angle based on the faulty phase. Figure 11 As shown, when the steering angle command value calculated by the automatic steering control unit 120 is within the range of the avoidance steering angle centered on the output decrease steering angle, the steering angle command value correction unit 133 changes the steering angle command value to outside the range of the avoidance steering angle (for example, the maximum or minimum angle of the range of the avoidance steering angle).

[0058] <When a circuit anomaly is detected in one phase> In the event of a detected short-circuit anomaly in one phase, for example, the method disclosed in International Publication No. WO2007 / 129359 can be used. Specifically, if the method described in International Publication No. WO2007 / 129359 is applicable... Figure 3 If the method is similarly configured, then the motor control unit 150 is as follows: Figure 12 As shown, it includes a target phase current shaping unit 151C, a deviation calculation unit 152C, and an abnormal current control unit 153C. The target phase current shaping unit 151C converts the q-axis current command value into the current command value of each of the three phases based on the information of the abnormal phase and the rotation angle θ. Figure 12 The diagram illustrates a situation where phase V is abnormal, while phases U and W are normal. Then, for each of the three phases, the deviation calculation unit 152C calculates the deviation between the current command value and the current detection value, and subtracts the deviation of the abnormal phase from the deviations of the two normal phases. In the abnormal situation, the current control unit 153C, for each of the two normal phases, calculates a feedback value using feedback control such as PI control based on the current deviation after subtracting the deviation of the abnormal phase. It then subtracts half the power supply voltage Vdc from the feedback value to calculate the voltage command value, and based on the voltage command values ​​of the two normal phases, uses PWM control to generate drive signals that turn the switching elements of each of the two normal phases on and off. In the abnormal situation, the current control unit 153C generates a drive signal that keeps the switching elements of the abnormal phase always off.

[0059] For example, international publication WO2007 / 129359 Figure 5 As shown, at the specific rotation angle corresponding to the abnormal phase, in order to suppress the generation of braking torque, the current does not flow through the normal two-phase armature winding. Therefore, the steering motor 5 cannot output torque, and the output torque drops to 0.

[0060] When the U-phase is abnormal, the output torque drops to 0 when the rotation angle θ is between 240 and 300 degrees. When the V-phase is abnormal, the output torque drops to 0 when the rotation angle θ is between 0 and 60 degrees. When the W-phase is abnormal, the output torque drops to 0 when the rotation angle θ is between 120 and 180 degrees.

[0061] The steering angle command value correction unit 133 corrects the steering angle command value so that when a short circuit abnormality is detected in any one phase, the output torque is prevented from decreasing by the steering angle corresponding to the rotation angle of the steering motor that causes the short circuit abnormality. Then, the output command calculation unit 131 calculates the motor output command value when the abnormality occurs based on the corrected steering angle command value and the steering angle detection value.

[0062] According to this structure, the steering angle is controlled to avoid a decrease in the output torque of the steering motor. Therefore, the situation of staying at the rotation angle where the output torque decreases is suppressed. Even if a circuit abnormality in any one phase is detected, the steering motor can still output torque and continue automatic steering or steering assistance.

[0063] As described above, the cumulative value of the rotation angle multiplied by the conversion coefficient corresponding to the gear ratio is the steering angle. As mentioned above, when a short-circuit fault occurs in one phase, the relationship between the abnormal phase and the range of rotation angles causing the output torque decrease is known; therefore, the relationship between the abnormal phase and the range of the output torque decrease steering angle can also be determined. Therefore, the steering angle command value correction unit 133 sets the range of the output torque decrease steering angle based on the abnormal phase. Figure 11 As shown, when the steering angle command value calculated by the automatic steering control unit 120 is within the range of the output decreasing steering angle, the steering angle control unit 130 changes the steering angle command value to outside the range of the avoidance steering angle (for example, the maximum or minimum angle of the avoidance steering angle range).

[0064] Therefore, the steering angle command correction unit 133 adjusts the steering angle to avoid a decrease in output based on the type and phase of the circuit abnormality, such as open circuit or short circuit.

[0065] 1-2-7-2. Control when an abnormality is detected in the current sensor As described above, when no abnormality is detected in the current sensor, the motor control unit 150 generates a drive signal based on the motor output command value and the current detection value detected by the current sensor. On the other hand, when an abnormality is detected in the current sensor, the motor control unit 150 does not use the current detection value, but generates a drive signal based on the motor output command value instead.

[0066] According to this structure, even when an abnormality is detected in the current sensor, the steering motor can output torque and the automatic steering or steering assist can continue.

[0067] In this embodiment, such as Figure 13 As shown, the motor control unit 150 when an abnormality is detected in the current sensor includes a rotation detection unit 151, a current command setting unit 153, a voltage command setting unit 157, a voltage command coordinate conversion unit 155, and a PWM control unit 156. The structures of the rotation detection unit 151, the current command setting unit 153, and the voltage command coordinate conversion unit 155 are the same as in normal operation.

[0068] When the voltage command setting unit 157 detects an abnormality in the current sensor, it uses the motor voltage equation shown below to calculate the d-axis voltage command value Vdo and the q-axis voltage command value Vqo based on the d-axis current command value Ido and the q-axis current command value Iqo. [Mathematical Expression 1]

[0069] Here, s is the Laplace operator, and R is the winding resistance. Ld is the linkage flux generated by the rotor magnet, Lq is the d-axis inductance, Lq is the q-axis inductance, and ω is the rotational angular velocity at the electrical angle. Furthermore, the phase advance of the Laplace operator s can be omitted. In addition, various known methods can be used.

[0070] Then, as in normal operation, the voltage command coordinate conversion unit 155 performs fixed coordinate conversion and two-phase / three-phase conversion on the d-axis voltage command value Vdo and the q-axis voltage command value Vqo based on the rotation angle (magnetic pole position), and converts them into three-phase voltage command values. Furthermore, the PWM control unit 156 generates drive signals that turn on and off each switching element of the motor drive circuit 30 based on the three-phase voltage command values ​​using PWM (Pulse Width Modulation) control.

[0071] A current sensor 31 is provided to detect the current of each of the three phases. If an abnormality is detected in the current sensor of one phase, the motor control unit 150 and... Figure 8 The block diagram for normal operation is constructed similarly. The current detection unit 152 detects the sum of the current detection values ​​of the three phases when the total is 0, multiplying the sum of the current detection values ​​of the two normal phases by -1, and uses this as the current detection value for the abnormal phase. In this case, the current feedback control along the d-axis and q-axis is performed using the current detection values ​​of all three phases, just as in normal operation. On the other hand, when an abnormality is detected in two or more current sensors, as described above... Figure 13As shown in the block diagram, instead of using current sensing values, the drive signal is generated based on the motor output command value.

[0072] Alternatively, when an anomaly is detected in the current sensor, the drive signal can be calculated using a steering angle motor control unit 170, which integrates the steering angle control unit 130 and the motor control unit 150. For example... Figure 14 As shown, the steering angle motor control unit 170 includes a steering voltage command calculation unit 171, a coordinate transformation unit 172, and a PWM control unit 173. The steering voltage command calculation unit 171 calculates the voltage command values ​​for the d-axis and q-axis based on the steering angle command value and the steering angle detection value. The steering voltage command calculation unit 171 includes: a feedback controller that changes the control value to make the steering angle detection value close to the steering angle command value; and a phase advance unit that has the characteristics of the inverse model (R+s×L) of the motor. L is the inductance. The coordinate transformation unit 172 performs fixed coordinate transformation and two-phase / three-phase transformation on the d-axis and q-axis voltage command values ​​based on the rotation angle (pole position), converting them into three-phase voltage command values. The PWM control unit 173 generates drive signals that turn on and off each switching element of the motor drive circuit 30 based on the three-phase voltage command values ​​through PWM control (Pulse Width Modulation). According to this structure, the dedicated steering angle motor control unit 170 can properly control the steering angle motor when the current sensor 31 malfunctions.

[0073] 1-2-7-3. Control when an abnormality is detected in the rotation angle sensor As described above, when no abnormality is detected in the rotation angle sensor 32, the motor control unit 150 generates a drive signal based on the rotation angle detected by the rotation angle sensor 32. Furthermore, as described above, when no abnormality is detected in the rotation angle sensor 32, the steering angle control unit 130 detects the steering angle based on the cumulative value of the rotation angle detected by the rotation angle sensor 32, and calculates the motor output command value based on the steering angle command value and the detected steering angle value.

[0074] On the other hand, when an abnormality is detected in the rotation angle sensor 32, the motor control unit 150 estimates the rotation angle based on the current flowing through the steering motor and generates a drive signal based on the estimated rotation angle. Furthermore, when an abnormality is detected in the rotation angle sensor 32, the steering angle control unit 130 detects the steering angle based on the cumulative value of the rotation angle estimated by the motor control unit 150, and calculates the motor output command value based on the steering angle command value and the detected steering angle value. Except for the structure that uses the estimated rotation angle value instead of the detected rotation angle value, everything else is the same as in normal operation.

[0075] According to this structure, when the rotation angle sensor 32 malfunctions, the rotation angle can be estimated, and the motor control and steering angle control can continue based on the estimated value of the rotation angle, so that automatic steering can continue.

[0076] <Motor control unit when rotation angle sensor malfunctions> For example, the method disclosed in Japanese Patent No. 6203435 can be used. Figure 15 As shown, the motor control unit 150, when an abnormality is detected in the rotation angle sensor, includes a rotation estimation unit 158, an estimation voltage command setting unit 159, a current detection unit 152, a current command setting unit 153, a current feedback control unit 154, a voltage command coordinate conversion unit 155, and a PWM control unit 156. The current detection unit 152, the current command setting unit 153, the current feedback control unit 154, and the voltage command coordinate conversion unit 155 use the estimated value of the rotation angle estimated by the rotation estimation unit 158 ​​to replace the detected value of the rotation angle, and perform the same processing as during normal operation.

[0077] The voltage command setting unit 159 for estimation has a frequency for angle estimation that is different from the rotation frequency, and calculates the voltage command correction values ​​for the three phases of the angle estimation for three-phase balance. Then, the voltage command correction values ​​for the three phases of the angle estimation are added and corrected with the voltage command values ​​for the three phases output from the voltage command coordinate conversion unit 155, and the voltage command values ​​for the three phases after addition and correction are input to the PWM control unit 156.

[0078] Rotational presupposition 158 and Japanese Patent No. 6203435 Figure 2 The same structure can be used. For example... Figure 16 As shown, the rotation estimation unit 158 ​​includes a position estimation current extractor 158a, a current amplitude calculator 158b, and a position calculator 158c. The position estimation current extractor 158a processes the current detection values ​​of each phase to extract frequency components for angle estimation. This extraction process uses a bandpass filter, a notch filter, etc. The current amplitude calculator 158b calculates the amplitude of the extracted frequency components for angle estimation of each phase. The amplitude calculation uses Fourier transform or equation (2) of Japanese Patent No. 6203435. The position calculator 158c calculates the estimated value of the rotation angle based on the amplitude of each phase. For example, after performing a two-phase conversion on the amplitudes of the three phases, the position calculator 158c performs an inverse cosine operation on the ratio of the amplitudes of the two phases to calculate the estimated value of the rotation angle. Other methods for calculating the estimated value of the rotation angle may also be used.

[0079] Alternatively, the method disclosed in "Response Improvement Method for Sensorless Control of IPMSM Using Adaptive Observers Based on Direct Form Adaptive Control" (Electrical Theory D, Vol. 123, No. 5, pp. 600-609) can be used. Figure 1 And equations (1) to (12). The rotation estimation unit 158 ​​is configured to have a so-called adaptive observer. As the structure of the adaptive observer, in the above-mentioned literature, the state variables are set as armature reaction Φa and rotor flux Φr, the input variable is set as voltage vs, and the output variable is set as current is. The state variable can also be set as current is. If the state equation is established based on these variables, the rotational angular velocity ω can be estimated, and by integrating the rotational angular velocity ω, the estimated value of the rotation angle θ can be obtained.

[0080] Alternatively, the method disclosed in Japanese Patent No. 6095851 can be used. (This is related to Japanese Patent No. 6095851.) Figure 2 The same structure can be used. For example... Figure 17 As shown, the rotation estimation unit 158 ​​includes a bandpass filter 158d, an estimation error calculation unit 158e, and an estimation error control unit 158f. The bandpass filter 158d extracts a signal near the frequency of the high-frequency current on the dq axis from the torque detection value detected by the torque sensor that detects the output torque of the steering motor, and outputs it as the high frequency of the output torque. The estimation error calculation unit 158e calculates the rotation angle estimation error based on the high-frequency current on the dq axis and the high frequency of the output torque. This rotation angle estimation error is the phase difference between the actual dq axis based on the actual rotation angle and the estimated dq axis based on the estimated value of the rotation angle. Here, the estimation error calculation unit 158e consists of a multiplier, an integrator, and an angle error estimator. The multiplier multiplies the high-frequency output torque with each high-frequency current on the dq axis to output the product on the dq axis. The integrator integrates the product on the dq axis over time within an interval corresponding to one cycle of the high-frequency current on the dq axis to output the relevant value on the dq axis. The angle error estimator divides the relevant value on the d axis by the relevant value on the q axis, performs an arctangent operation on the resulting value, and outputs it as the rotation angle estimation error. The estimation error control unit 158f consists of a PI controller and calculates the estimated value of the rotation angle when the rotation angle estimation error is zero. Thus, the rotation estimation unit 158 ​​calculates the estimated value of the rotation angle based on the torque detection value output by the output torque sensor and the high-frequency current on the dq axis.

[0081] When the steering angle control unit 130 detects an abnormality in the rotation angle sensor 32, it estimates the steering angle based on the detected driving state and calculates the motor output command value based on the steering angle command value and the steering angle detection value. Except for the structure of the steering angle detection unit 132 for estimating the steering angle, it is the same as in normal operation.

[0082] When the steering angle detection unit 132 detects an anomaly in the rotation angle sensor 32, it estimates the steering angle based on the vehicle speed and yaw acceleration as the driving state. For example, the yaw acceleration has a predetermined relationship that is proportional to both the steering angle and the vehicle speed, so the steering angle can be estimated using this proportional relationship. Alternatively, if the vehicle speed is determined by detecting the rotational speeds of the left and right wheels respectively, the steering angle detection unit 132 can estimate the steering angle based on the difference in rotational speeds between the left and right wheels.

[0083] <Example 1 of the variation in calculating the motor output command value when the steering angle detection value is abnormal> Alternatively, when an anomaly is detected in the steering angle detection value (in this example, when an anomaly is detected in the rotation angle sensor), the automatic steering control unit 120 may be configured to calculate the motor output command value based on the detected surrounding conditions, without using the steering angle detection value, instead of the steering angle control unit 130. The automatic steering control unit 120 detects the lateral position of the vehicle relative to the driving lane based on the detected surrounding conditions, and calculates the motor output command value based on the target lateral position and the detected lateral position.

[0084] like Figure 18 As shown, the automatic steering control unit 120, when an abnormality in the steering angle detection value is detected, includes a target driving trajectory calculation unit 126, a lateral position detection unit 127, and a track following control unit 128. The target driving trajectory calculation unit 126 generates a target driving trajectory in the same way as the automatic steering control unit 120 in normal operation. The lateral position detection unit 127 detects the lateral position of the vehicle relative to the lane based on the detected surrounding conditions. For example, it detects the lateral position of the vehicle relative to the left and right dividing lines based on detection information from a surrounding monitoring device 20 such as a camera. The track following control unit 128 calculates the deviation of the vehicle's lateral position from the target driving trajectory and calculates the motor output command value based on the lateral position deviation. For example, the track following control unit 128 performs feedback control that changes the motor output command value to reduce the lateral position deviation. During the calculation of the motor output command value, phase advance processing, such as differential control, is performed to improve the following responsiveness.

[0085] <Example 2 of the variation in calculating the motor output command value when the steering angle detection value is abnormal> Alternatively, when an abnormality is detected in the steering angle detection value (in this example, when an abnormality is detected in the rotation angle sensor), the steering angle control unit 130 may be configured to calculate the motor output command value based on the steering angle command value instead of using the steering angle detection value.

[0086] like Figure 19 As shown, the steering angle control unit 130, which detects an abnormality in the steering angle detection value, includes a steering angle feedforward control unit 134. The steering angle feedforward control unit 134 does not use the steering angle detection value, but instead calculates the motor output command value based on the steering angle command value. The relationship between the steering angle δ and the motor q-axis current Iq is expressed as follows. [Mathematical Expression 2] Here, Tmot is the output torque of the steering motor, Kt is the torque constant converted from current to torque, J is the moment of inertia of the steering mechanism, C is the viscosity of the steering mechanism, and k is the spring constant obtained by linearly approximating inertia, viscosity, and road reaction force.

[0087] Therefore, by performing a Laplace transform on equation (2) and using the transformed equation, the steering angle feedforward control unit 134 performs feedforward calculation on the steering angle command value δo to calculate the current command value Iqo of the q-axis. In addition, the steering angle feedforward control unit 134 can calculate the torque command value obtained by multiplying the current command value Iqo of the q-axis by the torque constant Kt. [Mathematical Expression 3]

[0088] 2. Implementation Method 2 The autonomous driving assistance device 1 according to Embodiment 2 will be described with reference to the accompanying drawings. Descriptions of structural parts identical to those in Embodiment 1 are omitted. The basic structure of the autonomous driving assistance device 1 according to this embodiment is the same as that in Embodiment 1, but the difference lies in the inclusion of a steering angle sensor 9, and the corresponding changes to various processing steps. Figure 20 The diagram shows a simplified structural diagram of the autonomous driving assistance device 1. Figure 21 A simplified block diagram of the autonomous driving assistance device 1 is shown. Furthermore, Figure 22 The diagram below shows a summary of the processing for anomaly detection of each sensor. Except for the processing for anomaly detection involving the steering angle sensor 9, it is the same as in Embodiment 1.

[0089] In this embodiment, the autonomous driving assistance device 1 includes a steering angle sensor 9, which detects the steering angle of the steering device 8 (wheel). The output signal of the steering angle sensor 9 is input to the control device 100. The steering angle sensor 9 is mounted on the steering shaft 4 and detects the rotation angle of the steering shaft 4. Similar to the torque sensor 3, the steering angle sensor 9 is mounted on the portion of the steering shaft 4 between the steering motor 5 and the steering wheel 2.

[0090] The rotation angle and steering angle of the steering shaft 4 have a proportional relationship after being multiplied by a predetermined conversion ratio. The steering angle sensor 9 can also be installed in other parts that can detect the steering angle of the rack, pinion 6, etc. In this embodiment, the steering angle sensor 9 is a high-resolution sensor capable of detecting rotation angle changes of several degrees.

[0091] The anomaly detection unit 160 detects anomalies in the steering angle sensor 9. Various known methods are used to detect faults in the steering angle sensor 9.

[0092] <Structure of the steering angle control unit under normal steering angle sensor conditions> Similar to Embodiment 1, the steering angle control unit 130 calculates a motor output command value related to the output torque of the steering motor 5 based on the steering angle command value and the steering angle detection value. For example... Figure 23 As shown, the steering angle control unit 130 includes an output command calculation unit 131 and a steering angle detection unit 132. In this embodiment, when no abnormality is detected in the steering angle sensor 9, the steering angle detection unit 132 uses the steering angle sensor 9 to detect the steering angle. Specifically, the steering angle detection value is calculated by multiplying the rotation angle of the steering shaft 4 detected by the steering angle sensor 9 by a predetermined conversion ratio. The rotation angle when the steering angle is 0 is set to 0. In this embodiment, the steering angle sensor 9 is a high-resolution sensor; therefore, the steering angle detection value detected by the output signal of the steering angle sensor 9 can be used directly, but the steering angle detection value after smoothing processing such as a bandpass filter or a PLL filter can also be used.

[0093] Similar to Embodiment 1, the output command calculation unit 131 uses feedback control such as PI control based on the deviation between the steering angle command value and the steering angle detection value to change the motor output command value (in this example, the current command value of the q-axis).

[0094] <Structure of the steering angle control unit when an abnormality is detected in the steering angle sensor> like Figure 24As shown, when the steering angle detection unit 132 detects an abnormality in the steering angle sensor 9, it detects the steering angle based on the cumulative value of the rotation angle of the steering motor. Specifically, the steering angle detection unit 132 calculates the steering angle detection value by multiplying the cumulative value of the rotation angle by a conversion coefficient preset according to the gear ratio. The cumulative value of the rotation angle when the steering angle is 0 is set to 0. The steering angle detection unit 132 acquires and accumulates the rotation angle of the steering motor 5 detected or estimated by the motor control unit 150. When the steering angle sensor 9 is operating normally, the steering angle detection unit 132 stores the correspondence between the steering angle detection value detected by the steering angle sensor 9 and the cumulative value of the rotation angle. When an abnormality is detected in the steering angle sensor 9, the steering angle detection unit 132 uses the correspondence stored during normal operation to calculate the steering angle detection value based on the cumulative value of the rotation angle. For example, when the steering angle sensor 9 is operating normally, the steering angle detection unit 132 sets the cumulative value of the rotation angle when the steering angle detection value detected by the steering angle sensor 9 is 0 to 0, and calculates the cumulative value of the rotation angle based on 0.

[0095] In addition, similar to Embodiment 1, when no abnormality is detected in the rotation angle sensor 32, the rotation angle of the steering motor 5 detected by the rotation angle sensor 32 is used; when an abnormality is detected in the rotation angle sensor 32, the rotation angle of the steering motor 5 estimated by the motor control unit 150 is used.

[0096] According to the above structure, even if the steering angle sensor 9 malfunctions, the steering angle detection value can be calculated based on the cumulative value of the rotation angle of the steering motor 5 detected or estimated by the motor control unit 150, and the automatic steering can continue.

[0097] Alternatively, with implementation method 1 Figure 18 Similarly, when an anomaly is detected in the steering angle detection value (in this example, when an anomaly is detected in the steering angle sensor 9), instead of the steering angle control unit 130, the automatic steering control unit 120 can be configured to calculate the motor output command value based on the detected surrounding conditions, without using the steering angle detection value. The automatic steering control unit 120 detects the lateral position of the vehicle relative to the driving lane based on the detected surrounding conditions, and calculates the motor output command value based on the target lateral position and the detected lateral position. The detailed structure is the same as in Embodiment 1, and therefore omitted.

[0098] Furthermore, or in accordance with implementation method 1 Figure 19 Similarly, when an abnormality is detected in the steering angle detection value (in this example, when an abnormality is detected in the steering angle sensor 9), the steering angle control unit 130 can be configured to calculate the motor output command value based on the steering angle command value instead of using the steering angle detection value. The detailed structure is the same as in Embodiment 1, so it is omitted.

[0099] <Structure of the steering assist control unit when an abnormality is detected in the torque sensor> The anomaly detection unit 160 detects anomalies in the torque sensor 3, which detects steering torque. Various known methods are used to detect faults in the torque sensor 3.

[0100] When an anomaly is detected in the torque sensor 3, the steering method determination unit 110 or the steering assist control unit 140 estimates the steering torque based on the angle deviation between the steering angle detection value detected by the steering angle sensor 9 and the estimated steering angle value estimated based on the cumulative value of the rotation angle of the steering motor 5. The angle deviation allows the detection of the torsional angle of the power transmission path (steering shaft 4) between the position of the steering device 8 (steering shaft 4 in this example) where the steering angle sensor 9 is mounted and the position of the steering device 8 (steering shaft 4 in this example) where the steering motor 5 is mounted. By multiplying the torsional angle by a spring constant, the torsional torque, which corresponds to the steering torque, can be calculated. Therefore, the steering method determination unit 110 or the steering assist control unit 140 multiplies the angle deviation by a preset spring constant and uses the resulting value as the steering torque.

[0101] Then, the steering method determination unit 110 determines whether to perform automatic steering or steering assist based on the estimated steering torque. Furthermore, if it is determined that steering assist should be performed, the steering assist control unit 140 calculates the motor output command value based on the estimated steering torque, in the same manner as in Embodiment 1.

[0102] Even in the event of an anomaly in torque sensor 3, the steering torque corresponding to the torsional torque can be estimated based on the angle deviation between the steering angle detection value detected by steering angle sensor 9 and the estimated steering angle value estimated based on the cumulative value of rotation angle, and the steering method determination and steering assist control can continue.

[0103] Alternatively, when an anomaly is detected in the torque sensor 3, the steering method determination unit 110 can determine whether the driver has a driving intention based on one or both of the accelerator pedal operation amount and brake pedal operation amount detected by the sensor, and determine whether to engage automatic steering or steering assist. If the accelerator pedal operation amount exceeds the determination value, or if the brake pedal operation amount exceeds the determination value, the steering method determination unit 110 can determine to engage steering assist; otherwise, it can determine to engage automatic steering.

[0104] <Structure of the automatic steering control unit when a status detection anomaly is detected> The anomaly detection unit 160 detects anomalies in either the driving state or the surrounding state, i.e., a state detection anomaly. The anomaly detection unit 160 detects anomalies in the driving state detection device 21. In this embodiment, the anomaly detection unit 160 detects anomalies in at least the vehicle speed sensor that detects vehicle speed, the yaw rate sensor that detects yaw rate, and the lateral acceleration sensor that detects lateral acceleration.

[0105] The anomaly detection unit 160 detects anomalies in the surrounding monitoring device 20. In this embodiment, the anomaly detection unit 160 detects anomalies in cameras, radars, etc. Various known methods are used to detect malfunctions in each sensor and device.

[0106] When the automatic steering control unit 120 detects a state detection abnormality, it infers that an abnormal driving state or surrounding state has been detected based on one or both of the driving state and the surrounding state that have not detected an abnormality, and calculates the steering angle command value based on the detected or inferred driving state and surrounding state.

[0107] According to this structure, when an abnormality is detected in either the driving state or the surrounding state, the abnormal driving state or the surrounding state can be inferred based on one or both of the driving state and the surrounding state where no abnormality is detected, and the automatic steering control can continue.

[0108] Similar to Embodiment 1, when no abnormality is detected in the vehicle speed sensor, yaw rate sensor and lateral rate sensor, the automatic steering control unit 120 calculates the steering command value based on the detected values ​​of vehicle speed, yaw rate and lateral acceleration.

[0109] On the other hand, when an abnormality is detected in any of the vehicle speed sensor, yaw rate sensor, and lateral acceleration sensor, the automatic steering control unit 120 infers the driving state of the abnormal sensor based on one or both of the driving state detection value obtained from the normal sensor and the steering angle detection value, and calculates the steering angle command value based on the driving state detection value obtained from the normal sensor and the inferred driving state value of the abnormal sensor.

[0110] According to this structure, in the event of a failure of any of the vehicle speed sensor, yaw angle sensor, and lateral acceleration sensor, the driving state of the abnormal sensor can be inferred based on the normal detection value, and the automatic steering control can continue.

[0111] <When an anomaly is detected in the yaw rate sensor> When an anomaly is detected in the yaw rate sensor, the automatic steering control unit 120 estimates the yaw rate based on the detected steering angle and vehicle speed. As described above, yaw acceleration has a predetermined relationship that is proportional to both the steering angle and the vehicle speed; therefore, this proportional relationship can be used to estimate the yaw rate. Alternatively, when the rotational speeds of the left and right wheels are detected as the vehicle speed, the automatic steering control unit 120 can determine the rotational state based on the difference in rotational speeds between the left and right wheels and estimate the yaw rate.

[0112] 3. Implementation Method 3 The autonomous driving assistance device 1 according to Embodiment 3 will be described with reference to the accompanying drawings. Descriptions of structural parts identical to those in Embodiments 1 or 2 are omitted. The basic structure of the autonomous driving assistance device 1 according to this embodiment is the same as that in Embodiment 2, but the difference lies in the inclusion of a low-resolution steering angle sensor 9, and the corresponding changes to the processing methods. Figure 25 The diagram below shows a summary of the processing for anomaly detection of each sensor. Except for the processing for anomaly detection involving the low-resolution steering angle sensor 9, it is the same as in Embodiment 1 or 2.

[0113] <Structure of steering angle sensor malfunction and steering detection during malfunction> Similar to Embodiment 1, the steering angle control unit 130 calculates a motor output command value related to the output torque of the steering motor 5 based on the steering angle command value and the steering angle detection value. For example... Figure 26 As shown, the steering angle control unit 130 includes an output command calculation unit 131 and a steering angle detection unit 132.

[0114] In this embodiment, the angle detection resolution of the steering angle detection value obtained based on the cumulative value of the rotation angle of the steering motor is higher than that of the steering angle detection value obtained by the steering angle sensor 9. Therefore, it is desirable to use a high-resolution steering angle that can be estimated from the cumulative value of the rotation angle of the steering motor to compensate for the low-resolution steering angle obtained by the steering angle sensor 9. On the other hand, if the rotation angle of the steering motor relative to the steering angle is not strictly managed during assembly, the correspondence between the cumulative value of the rotation angle of the steering motor and the steering angle is uncertain, and it is impossible to convert the cumulative value of the rotation angle into the steering angle.

[0115] Therefore, when no abnormality is detected in the steering angle sensor 9, the steering angle detection unit 132 determines the correspondence between the cumulative value of the rotation angle of the steering motor and the steering angle based on the steering angle detection value obtained from the steering angle sensor 9, and detects the steering angle based on the determined correspondence and the cumulative value of the rotation angle of the steering motor. The determined correspondence is stored in a non-volatile storage device such as an EEPROM. On the other hand, when an abnormality is detected in the steering angle sensor, the steering angle detection unit 132 detects the steering angle based on the correspondence determined when no abnormality is detected in the steering angle sensor and the cumulative value of the rotation angle of the steering motor.

[0116] According to this structure, when the steering angle sensor 9 is functioning normally, the correspondence between the cumulative value of the rotation angle and the steering angle is determined. Regardless of whether the steering angle sensor 9 is functioning normally or abnormally, the determined correspondence can be used to detect a high-resolution and high-precision steering angle by utilizing the cumulative value of the rotation angle.

[0117] For example, when the steering angle sensor 9 is functioning normally, the steering angle detection unit 132 sets the cumulative value of the rotation angle when the steering angle detection value obtained by the steering angle sensor 9 is 0 to 0, and calculates the cumulative value of the rotation angle when the steering angle 0 is set to 0, as a correspondence. The steering angle detection unit 132 calculates the steering angle detection value by multiplying the cumulative value of the rotation angle by a conversion coefficient preset according to the gear ratio.

[0118] Similar to Embodiment 1, the output command calculation unit 131 changes the motor output command value (in this example, the q-axis current command value) by feedback control such as PI control based on the deviation between the steering angle command value and the steering angle detection value.

[0119] <Steering detection when the rotation angle sensor malfunctions> In this embodiment, such as Figure 27 As shown, when an anomaly is detected in the rotation angle sensor 32, the steering angle detection unit 132 smooths the steering angle detection value obtained from the steering angle sensor 9 and detects the steering angle. As a smoothing process, a low-pass filter or a PLL filter is used. When the rotation angle sensor 32 malfunctions, if the accumulated value of the rotation angle cannot be used to calculate the steering angle detection value, or if the calculation accuracy decreases due to the estimated value of the rotation angle, the smoothing process can improve the resolution of the steering angle detection value obtained from the low-resolution steering angle sensor 9 and make it usable.

[0120] Furthermore, when an abnormality is detected in the rotation angle sensor 32, the steering angle detection unit 132 can use the rotation angle of the steering motor 5 estimated by the motor control unit 150 to detect the steering angle based on the steering angle detection value obtained from the steering angle sensor 9 and the cumulative value of the estimated rotation angle of the steering motor, just as when the rotation angle sensor 32 is normal.

[0121] 4. Implementation Method 4 The autonomous driving assistance device 1 according to Embodiment 4 will be described with reference to the accompanying drawings. Descriptions of structural parts identical to those in Embodiments 1 or 2 are omitted. The basic structure of the autonomous driving assistance device 1 according to this embodiment is the same as that in Embodiments 1 or 2, but the difference lies in that the steering motor 5 is a brushed DC motor, and the motor drive circuit 30 and various processing steps are changed accordingly. Figure 28 The diagram shows a simplified structural diagram of the autonomous driving assistance device 1. Figure 29 A simplified block diagram of the autonomous driving assistance device 1 is shown. Furthermore, Figure 30 The diagram below summarizes the processing steps for anomaly detection by each sensor.

[0122] <DC motor with brushes> The steering motor 5 is a so-called brushed DC motor. The stator has permanent magnets, and the rotor has multiple armature windings. A commutator is located on the rotor's rotating shaft, and brushes are located on the non-rotating components that contact the commutator. The commutator has multiple electrode plates spaced apart from each other and arranged circumferentially on the outer periphery of the rotating shaft. Each electrode plate is connected to the end of a specific armature winding. The brushes have a first electrode brush 35a and a second electrode brush 35b. One brush is connected to the positive side of the DC power supply 34 via a motor drive circuit 30, and the other brush is connected to the negative side of the DC power supply 34 via the same circuit. As the rotor rotates, the electrode plates of the commutator contacted by the first and second electrodes brushes 35a and 35b switch, and the brush windings supplying current switch. This generates a magnetic field in the rotor that causes it to rotate. The torque generated in the rotor varies depending on the current supplied to the armature windings.

[0123] <Motor Drive Circuit> The motor drive circuit 30 has a switching element that switches the power supplied to the steering motor 5 on and off. In this embodiment, as... Figure 31As shown, the motor drive circuit 30 is configured as an H-bridge circuit. Specifically, the motor drive circuit 30 has two sets of series circuits, wherein the series circuits are formed by connecting a high-potential side switching element Sp connected to the high-potential side of the DC power supply 34 and a low-potential side switching element Sn connected to the low-potential side of the DC power supply 34 in series. The connection point of the two switching elements in the first set of series circuits is connected to the brush 35a of the first electrode, and the connection point of the two switching elements in the second set of series circuits is connected to the brush 35b of the second electrode.

[0124] By turning on the high-potential side switching element Sp1 of the first group and the low-potential side switching element Sn2 of the second group, the high-potential side of the DC power supply 34 is connected to the brush 35a of the first electrode, and the low-potential side of the DC power supply 34 is connected to the brush 35b of the second electrode, generating a torque that rotates the rotor to one side. By turning on the low-potential side switching element Sn1 of the first group and the high-potential side switching element Sp2 of the second group, the low-potential side of the DC power supply 34 is connected to the brush 35a of the first electrode, and the high-potential side of the DC power supply 34 is connected to the brush 35b of the second electrode, generating a torque that rotates the rotor to the other side.

[0125] The motor drive circuit 30 has a current sensor 31 that detects the current flowing through the armature winding of the steering motor 5. The current sensor 31 can be installed at any location, such as the brush side or the DC power supply 34 side, as long as the current flowing through the armature winding can be detected.

[0126] <Structure of the motor control unit under normal conditions> The motor control unit 150 generates a drive signal that turns the switching elements of the motor drive circuit 30 on and off based on the motor output command value (current command value in this example) calculated by the steering angle control unit 130 (described later). Figure 32 As shown, the motor control unit 150 under normal conditions includes a current detection unit 152, a current command setting unit 153, a current feedback control unit 154, and a PWM control unit 156. The current detection unit 152 detects the current flowing through the armature winding based on the output signal of the current sensor 31. The current command setting unit 153 sets the current command value based on the motor output command value.

[0127] The current feedback control unit 154 calculates the voltage command value based on the motor output command value (current command value in this example) and the current detection value. The current feedback control unit 154 performs feedback control to change the voltage command value so that the current detection value is close to the current command value. When the current command value is positive, the PWM control unit 156, based on the voltage command value, uses PWM control to control the on / off state of the high-potential side switching element Sp1 of the first group and the low-potential side switching element Sn2 of the second group, keeping the low-potential side switching element Sn1 of the first group and the high-potential side switching element Sp2 of the second group always off. When the current command value is negative, the PWM control unit 156, based on the voltage command value, uses PWM control to control the low-potential side switching element Sn1 of the first group and the high-potential side switching element Sp2 of the second group, keeping the high-potential side switching element Sp1 of the first group and the low-potential side switching element Sn2 of the second group always off. For example, the PWM control unit 156 controls the switching element to turn on and off by using the duty cycle obtained by dividing the voltage command value by the power supply voltage through PWM control.

[0128] <Structure of the motor control unit when a short circuit anomaly is detected> As for abnormalities related to the steering motor, if a short circuit fault occurs in the switching element, or a short circuit occurs in the circuit supply path to the high-potential side or low-potential side of the DC power supply 34, the abnormality detection unit 160 will be unable to supply current to the armature winding normally. Various known methods are used for detecting short circuit faults and determining the location of short circuits.

[0129] When a short circuit is detected, the motor control unit 150 (PWM control unit 156) keeps the switching element corresponding to the short circuit off, and, as in normal operation, uses PWM control to control the switching elements that do not correspond to the short circuit based on the voltage command value.

[0130] <Anomaly Detection of Current Sensors> The anomaly detection unit 160 detects an anomaly in the current sensor 31 as a related anomaly of the steering motor. Various known methods are used to detect the fault in the current sensor 31. For example, the anomaly detection unit 160 determines the anomaly of the current sensor 31 based on the current detection value when the drive signal is output to the motor drive circuit 30.

[0131] When no abnormality is detected in the current sensor, the motor control unit 150 generates a drive signal based on the motor output command value and the current detection value detected by the current sensor. On the other hand, when an abnormality is detected in the current sensor, the motor control unit 150 does not use the current detection value, but generates a drive signal based on the motor output command value instead.

[0132] According to this structure, even when an abnormality is detected in the current sensor, the steering motor can output torque and the automatic steering or steering assist can continue.

[0133] In this embodiment, such as Figure 33 As shown, the motor control unit 150 when an anomaly of the current sensor is detected includes a current command setting unit 153, a voltage command setting unit 162, and a PWM control unit 156. The structures of the current command setting unit 153 and the PWM control unit 156 are the same as in normal operation. The voltage command setting unit 162 calculates the voltage command value based on the motor output command value (in this example, the current command value). For example, the voltage command setting unit 162 calculates the voltage command value by multiplying the current command value by the resistance value of the armature winding. The voltage command setting unit 162 can perform phase advance processing on the current command value to represent the inverse model of the motor (R+s×L) to calculate the voltage command value. R is the resistance value of the armature winding, L is the inductance of the armature winding, and s is the Laplace operator.

[0134] <Structure when an anomaly is detected in the steering angle sensor> Similar to Embodiment 2, the autonomous driving assistance device 1 includes a steering angle sensor 9 for detecting the steering angle. An anomaly detection unit 160 detects an anomaly in the steering angle sensor 9. Similar to Embodiments 1 and 2, the steering angle control unit 130 calculates a motor output command value related to the output torque of the steering motor 5 based on the steering angle command value and the detected steering angle value. Similar to Embodiment 2... Figure 23 Similarly, when no abnormality is detected in the steering angle sensor 9, the steering angle detection unit 132 uses the steering angle sensor 9 to detect the steering angle. On the other hand, when an abnormality is detected in the steering angle sensor 9, the steering angle detection unit 132 detects the steering angle based on the cumulative value of the rotation angle of the steering motor 5.

[0135] like Figure 34 As shown, the motor control unit 150 for when the steering angle sensor 9 malfunctions includes a current detection unit 152, a current command setting unit 153, a current feedback control unit 154, a PWM control unit 156, and a high-frequency superposition unit 161. When the high-frequency superposition unit 161 detects a malfunction in the steering angle sensor 9, it superimposes the high-frequency component Vh onto the voltage command value calculated by the current feedback control unit 154. For example, the high-frequency component Vh is set as shown in the following formula. Here, Va is the amplitude of the high-frequency component Vh, ωh is the angular frequency of the high-frequency component Vh, and t is time. The high-frequency angular frequency ωh is set to an angular frequency higher than the cutoff angular frequency of the transmission characteristics of the motor mechanical system, so that torque fluctuations do not become large. [Mathematical Expression 4] Vh=Va×sin(ωh×t)…(4)

[0136] The voltage command value after the superposition of the high-frequency component Vh is input to the PWM control unit 156. Based on the voltage command value after the superposition of the high-frequency component Vh, the PWM control unit 156 uses PWM control to control the switching elements of the motor drive circuit 30 to turn on and off.

[0137] like Figure 35 As shown, when the steering angle detection unit 132 detects an abnormality in the steering angle sensor 9, it estimates the rotation angle of the steering motor based on the current detection value, and detects the steering angle based on the cumulative value of the rotation angle. In this embodiment, the method disclosed in "A Sensorless Angle Estimation Method Using a Brushed DC Motor with Resistance Variation Based on Contact Switching" (Electrical Theory D, Vol. 137, No. 11, pp. 827-836) is used. The steering angle detection unit 132 when the steering angle sensor 9 is abnormal includes an impedance estimation unit 132a, an induced voltage estimation unit 132b, and an angle conversion unit 132c.

[0138] Impedance estimation unit 132a uses equations (A) and (28) to (37) from the aforementioned documents. Impedance estimation unit 132a uses the following equation corresponding to equation (37) from the aforementioned documents to estimate the impedance Zm of the armature winding. Here, Ia is the amplitude of the high-frequency angular frequency component ωh of the current detection value. [Mathematical Expression 5]

[0139] The amplitude Va of the high-frequency component Vh is set by the high-frequency superposition unit 161 and is therefore known. The amplitude Ia of the current detection value is detected by performing discrete Fourier transform processing to extract the high-frequency angular frequency ωh component from the current detection value, or by notch filtering processing, etc.

[0140] The induced voltage estimation unit 132b uses the above-mentioned document. Figure 4 And equations (12) to (18). The induced voltage estimation unit 132b constitutes a so-called induced voltage observer, which calculates the angular velocity estimation value ωob based on the voltage command value before the superposition of the current detection value and the high-frequency component Vh, integrates the angular velocity estimation value ωob, and calculates the angle estimation value θob.

[0141] Figure 36 The behavior of the armature winding impedance Zm, estimated by equation (5), is shown. The impedance Zm varies periodically in a pulse-like manner, with each pulse-like variation corresponding to a specific rotation angle. The angle conversion unit 132c detects the timing of the pulse-like variation of the impedance Zm by comparing it with Zth. At the detection moment, it can be determined that the rotation angle has changed by a predetermined angle (π / 3 in this example) from the detection moment of the previous pulse-like variation.

[0142] However, the rotation direction cannot be detected solely by this determination. Therefore, the angle conversion unit 132c determines the rotation direction based on the angular velocity estimation value ωob estimated by the induced voltage estimation unit 132b. Specifically, as shown in the following formula, when a pulse-like change in impedance Zm is detected, if the angular velocity estimation value ωob is positive, the angle conversion unit 132c adds π / 3 to the previously updated angle estimation value θest_old and updates the angle thereafter as the angle estimation value θest. If the angular velocity estimation value ωob is negative, the angle conversion unit 132c subtracts π / 3 from the previously updated angle estimation value θest_old and updates the angle thereafter as the angle estimation value θest. [Mathematical Expression 6] When a pulse-like change in impedance Zm is detected, 1) When ωob > 0, θest=θest_old+π / 3…(6) 2) When ωob < 0, θest=θest_old-π / 3

[0143] Since the induced voltage is proportional to the angular velocity, when the angular velocity of the motor is sufficiently large, the estimation accuracy of the angle estimation value θob derived from the induced voltage becomes higher, while when the angular velocity of the motor is relatively small, the estimation accuracy derived from the induced voltage becomes lower. Therefore, when the angular velocity estimation value calculated based on the angular velocity estimation value ωob or the angle estimation value θest is smaller than the determination value, the angle conversion unit 132c selects the angle estimation value θest derived from the impedance variation as the estimation value of the rotation angle; when the angular velocity estimation value is larger than the determination value, the angle estimation value θob derived from the induced voltage is selected as the estimation value of the rotation angle.

[0144] Then, the angle conversion unit 132c accumulates the estimated value of the selected rotation angle and detects the steering angle based on the accumulated value. Specifically, the steering angle detection unit 132 calculates the steering angle detection value by multiplying the accumulated value of the rotation angle by a conversion coefficient preset according to the gear ratio. The steering angle storage unit 132d sets the accumulated value of the rotation angle when the steering angle is 0 to 0. When the steering angle sensor 9 is operating normally, the angle conversion unit 132c stores the correspondence between the steering angle detection value detected by the steering angle sensor 9 and the accumulated value of the rotation angle. When an abnormality is detected in the steering angle sensor 9, the steering angle detection unit 132 uses the correspondence stored during normal operation to calculate the steering angle detection value based on the accumulated value of the rotation angle. For example, when the steering angle sensor 9 is operating normally, the angle conversion unit 132c sets the accumulated value of the rotation angle when the steering angle detection value detected by the steering angle sensor 9 is 0 to 0, and calculates the accumulated value of the rotation angle based on 0.

[0145] As described above, even when using a brushed DC motor that does not utilize rotation angle for control, in the event of an abnormality in the steering angle sensor 9, the steering angle detection unit 132 can calculate the steering angle detection value based on the current detection value flowing through the brushed DC motor and the cumulative value of the rotation angle, and continue automatic steering.

[0146] 5. Implementation Method 5 The autonomous driving assistance device 1 according to Embodiment 5 will be described with reference to the accompanying drawings. Descriptions of structural parts identical to those in Embodiments 1 or 2 are omitted. The basic structure of the autonomous driving assistance device 1 according to this embodiment is the same as that in Embodiments 1 or 2, but the difference lies in the change of the structure of the steering device 8, and consequently, the changes to the structure of each component. Figure 37 The diagram shows a simplified structural diagram of the autonomous driving assistance device 1. Figure 38 A simplified block diagram of the autonomous driving assistance device 1 is shown. Furthermore, Figure 39 The diagram below summarizes the processing steps for anomaly detection by each sensor.

[0147] In this embodiment, the steering wheel 2 is not mechanically connected to the steering wheels, but is configured as a so-called steer-by-wire system. The steering shaft 4 is connected to the steering wheel 2. The rotation shaft of the reaction force motor 57 is connected to the steering shaft 4 via a reduction gear 51. The reaction force motor 57 outputs a reaction torque corresponding to the driver's steering torque on the steering wheel 2. The reaction force motor drive circuit 56 switches the power supplied to the reaction force motor 57 on and off. A reaction force motor rotation angle sensor 52 is provided for detecting the rotation angle of the reaction force motor 57. A reaction force current sensor 59 is provided for detecting the current flowing through the reaction force motor 57. On the steering shaft 4 between the reaction force motor 57, the reduction gear 51, and the steering wheel 2, a torque sensor 3 for detecting the driver's steering torque on the steering wheel 2, and a steering wheel angle sensor 50 for detecting the rotation angle of the steering wheel 2 are provided.

[0148] A rack and pinion 6 is provided. The rack and pinion 6 converts the rotational motion of the pinion shaft 58 into linear motion in the left and right directions, driving the connecting rod and steering knuckle arm, and changing the steering angle of the wheel 7. The rotational shaft of the steering motor 5 is connected to the pinion shaft 58 via a reduction gear 54. The motor drive circuit 30 switches the power supplied to the steering motor 5 on and off. A rotation angle sensor 32 is provided for detecting the rotational angle of the steering motor 5. A steering angle sensor 9 is provided on the pinion shaft 58.

[0149] The steering motor 5 is an AC motor with an armature winding of three or more phases, similar to that in Embodiment 1, and the motor drive circuit 30 is an inverter circuit similar to that in Embodiment 1. Furthermore, the reaction force motor 57 is an AC motor with an armature winding of three or fewer phases, similar to that in the steering motor 5, and the reaction force motor drive circuit 56 is an inverter circuit similar to that in the motor drive circuit 30.

[0150] like Figure 38 As shown, the control device 100 also includes a reaction torque command calculation unit 180, a reaction output command calculation unit 181, and a reaction motor control unit 182. The input / output device 92 of the control device 100 is connected to a steering wheel angle sensor 50, a reaction motor rotation angle sensor 52, a reaction current sensor 59, and a reaction motor drive circuit 56. Furthermore, the reaction torque command calculation unit 180, the reaction output command calculation unit 181, and the reaction motor control unit 182 can be provided in a different control device than the control device 100.

[0151] The reaction torque command calculation unit 180 calculates the reaction force motor torque command value based on the steering wheel angle detection value detected by the steering wheel angle sensor 50 and the vehicle speed. Furthermore, since the steering wheel angle and torque have the same relationship as in equation (2), the reaction force motor torque command value can be calculated by replacing the parameters of equation (3) with the equation obtained for this control, based on the steering wheel angle detection value. Alternatively, as in Japanese Patent No. 6628017... Figure 5 In that case, the torque command value of the reaction force motor can be calculated based on the basic mapping with vehicle speed as the input parameter, or the steering wheel angular velocity can be calculated by differentiating the steering wheel angle detection value, and the torque command value of the reaction force motor can be calculated by multiplying the damper gain obtained based on the vehicle speed with the steering wheel angular velocity.

[0152] The reaction force output command calculation unit 181 calculates the reaction force motor output command value based on the torque command value of the reaction force motor and the detected value of the steering torque detected by the torque sensor 3. For example, the reaction force output command calculation unit 181 uses PI control or the like to change the output command value of the reaction force motor so that the detected value of the steering torque is close to the torque command value of the reaction force motor. In this embodiment, the reaction force output command calculation unit 181 calculates the current command value of the q-axis as the output command value of the reaction force motor. The reaction force output command calculation unit 181 may also calculate the torque command value as the output command value of the reaction force motor.

[0153] The reaction force motor control unit 182 generates a drive signal that turns the switching element of the reaction force motor drive circuit 56 on and off based on the output command value of the reaction force motor. The reaction force motor control unit 182 is configured in the same way as the motor control unit 150 in Embodiment 1, so its description is omitted.

[0154] Furthermore, similar to the steering motor, the fault detection unit 160 detects faults generated by the control system of the reaction force motor, i.e., faults related to the reaction force motor. Similarly to the steering motor, when the reaction force motor-related fault is detected, the reaction force motor control unit 182 generates a drive signal corresponding to the fault based on the reaction force motor output command value. Furthermore, similar to the steering motor, the fault detection unit 160 detects a circuit fault in any one phase as a reaction force motor-related fault. Similarly to the steering motor, when a circuit fault in any one phase is detected, the reaction force motor control unit 182 generates a drive signal that turns the switching elements of the remaining normal phases on and off based on the reaction force motor output command value.

[0155] Similar to Embodiment 1, the steering method determination unit 110 determines whether to engage automatic steering or steering assist based on the detected value of the steering torque detected by the torque sensor 3. Furthermore, similar to Embodiment 1, when automatic steering is determined to be engaged, the automatic steering control unit 120 detects the vehicle's driving state and the surrounding environment, and calculates a steering angle command value based on the detected driving state and surrounding environment. Similarly to Embodiment 1, the steering angle control unit 130 calculates a motor output command value related to the output torque of the steering motor 5 based on the steering angle command value and the detected steering angle value. Similarly to Embodiment 1, when steering assist is determined to be engaged, the steering assist control unit 140, instead of the automatic steering control unit 120 and the steering angle control unit 130, calculates the motor output command value based on the detected steering torque value. Similarly to Embodiment 1, the motor control unit 150 generates a drive signal that turns the switching elements of the motor drive circuit 30 on and off based on the motor output command value.

[0156] Even in a steer-by-wire system, the control during each anomaly detection is the same as in embodiments 1 to 3, therefore, the description is omitted. That is, even in a steer-by-wire system, automatic steering or steering assist can continue through the same anomaly detection control as in embodiments 1 to 3.

[0157] Furthermore, similar to Embodiment 4, the steering motor 5 is a brushed DC motor, enabling control during anomaly detection in the same manner as in Embodiment 4. Similarly, similar to Embodiment 4, the reaction force steering motor 57 is a brushed DC motor, enabling control when anomalies related to the reaction force motor are detected, also in accordance with Embodiment 4.

[0158] While this application describes various exemplary embodiments and examples, the various features, methods, and functions described in one or more embodiments are not limited to the application of a particular embodiment and can be applied to the embodiments individually or in various combinations. Therefore, it can be considered that numerous modifications not illustrated are also included within the scope of the technology disclosed in this application. For example, this includes cases where at least one constituent element is modified, added to, or omitted, and cases where at least one constituent element is extracted and combined with constituent elements of other embodiments. Label Explanation

[0159] 1. Automated driving assistance device 5. Steering motor 9 steering angle sensors 20 Surrounding surveillance devices 21 Driving Status Detection Device 30 Motor Drive Circuit 31 Current Sensor 32 Rotation Angle Sensor 110 Steering Method Determination Unit 120 Automatic Steering Control Unit 130 Steering Angle Controller 140 Steering Assist Control Unit 150 Electric Motor Control Unit 160 Anomaly Detection Department.

Claims

1. An autonomous driving assistance device, characterized in that, include: An automatic steering control unit detects the driving status of the vehicle and the surrounding environment of the vehicle, and calculates the steering angle command value of the vehicle's steering device based on the detected driving status and surrounding environment. A steering motor that drives the steering device; An electric motor drive circuit having a switching element to turn the power supplied to the steering motor on and off; The steering angle control unit calculates a motor output command value related to the output torque of the steering motor based on the steering angle command value and the steering angle detection value. The motor control unit generates a drive signal that turns the switching element of the motor drive circuit on and off based on the motor output command value. as well as The anomaly detection unit detects anomalies generated by the control system of the steering motor, i.e., steering motor-related anomalies. When an abnormality related to the steering motor is detected, the motor control unit generates a drive signal corresponding to the content of the abnormality based on the motor output command value.

2. The autonomous driving assistance device as described in claim 1, characterized in that, include: The steering method determination unit determines, based on the detected value of the steering torque of the steering wheel by the driver, whether to use the automatic steering control unit and the steering angle control unit for automatic steering or to provide steering assistance to the driver. as well as A steering assist control unit, which, when determining that steering assist should be applied, replaces the automatic steering control unit and the steering angle control unit in calculating the motor output command value based on the detected steering torque value. The anomaly detection unit detects anomalies in the torque sensor that detects the steering torque. The steering method determination unit or the steering assist control unit estimates the steering torque based on the angle deviation between the steering angle detection value detected by the steering angle sensor and the estimated steering angle value estimated by accumulating the rotation angle of the steering motor.

3. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The steering motor is an AC motor with three or more armature windings. The motor drive circuit includes switching elements that apply a voltage switch to the armature winding of each phase to turn it on or off. The anomaly detection unit detects an anomaly in any one phase of the circuit as a related anomaly of the steering motor. When a circuit abnormality is detected in any one phase, the motor control unit generates a drive signal based on the motor output command value to turn the switching elements of the remaining normal phases on or off. The steering angle control unit corrects the steering angle command value and calculates the motor output command value when there is an abnormality based on the corrected steering angle command value and the steering angle detection value, so that when any one phase of the circuit is detected as abnormal, the output torque is avoided from decreasing by the steering angle corresponding to the rotation angle of the steering motor that corresponds to the circuit abnormality, i.e., the output decrease steering angle.

4. The autonomous driving assistance device as described in claim 3, characterized in that, The steering angle control unit adjusts the output steering angle based on the type and phase of the circuit abnormality, such as open circuit or short circuit.

5. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects anomalies in the current sensor that measures the current supplied to the steering motor, and identifies these anomalies as related to the steering motor. When no abnormality is detected in the current sensor, the motor control unit generates the drive signal based on the motor output command value and the current detection value detected by the current sensor. When an abnormality is detected in the current sensor, the current detection value is not used, and the drive signal is generated based on the motor output command value instead.

6. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects anomalies in the rotation angle sensor that measures the rotation angle of the steering motor, and identifies these anomalies as related to the steering motor. When no abnormality is detected in the rotation angle sensor, the motor control unit generates the drive signal based on the rotation angle of the steering motor detected by the rotation angle sensor. When an anomaly is detected in the rotation angle sensor, the rotation angle of the steering motor is estimated based on the current flowing through it, and the drive signal is generated based on the estimated rotation angle of the steering motor. When no abnormality is detected in the rotation angle sensor, the steering angle control unit detects the steering angle based on the cumulative value of the rotation angle of the steering motor detected by the rotation angle sensor. When an abnormality is detected in the rotation angle sensor, the steering angle is detected based on the cumulative value of the rotation angle of the steering motor estimated by the motor control unit, or the steering angle is estimated based on the detected driving state.

7. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects an anomaly in the steering angle detection value. When no abnormality is detected in the steering angle detection value, the steering angle control unit calculates the motor output command value based on the steering angle command value and the steering angle detection value. When an abnormality is detected in the steering angle detection value, the automatic steering control unit replaces the steering angle control unit and calculates the motor output command value based on the detected surrounding conditions instead of using the steering angle detection value.

8. The autonomous driving assistance device as described in claim 7, characterized in that, When the automatic steering control unit detects an abnormality in the steering angle detection value, it detects the lateral position of the vehicle relative to the driving lane based on the detected surrounding conditions, and calculates the motor output command value based on the target lateral position and the detected lateral position.

9. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects an anomaly in the steering angle detection value. When no abnormality is detected in the steering angle detection value, the steering angle control unit calculates the motor output command value based on the steering angle command value and the steering angle detection value. When an anomaly is detected in the steering angle detection value, the steering angle detection value is not used; instead, the motor output command value is calculated based on the steering angle command value.

10. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects anomalies in the steering angle sensor that detects the steering angle. When no abnormality is detected in the steering angle sensor, the steering angle control unit uses the steering angle sensor to detect the steering angle. When an anomaly is detected in the steering angle sensor, the steering angle is detected based on the cumulative value of the rotation angle of the steering motor.

11. The autonomous driving assistance device as claimed in claim 10, characterized in that, The steering motor is a brushed DC motor. The motor control unit calculates a voltage command value based on the motor output command value and the current detection value flowing through the brushed DC motor, and generates a drive signal to turn the switching elements of the motor drive circuit on and off based on the voltage command value. When an anomaly is detected in the steering angle sensor, a high-frequency component is superimposed onto the voltage command value. When the steering angle control unit detects an abnormality in the steering angle sensor, it estimates the rotation angle of the steering motor based on the current detection value.

12. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects anomalies in the steering angle sensor that detects the steering angle. Compared to the angle detection resolution based on the steering angle detection value obtained from the steering angle sensor, the angle detection resolution based on the cumulative value of the rotation angle of the steering motor is higher. When no abnormality is detected in the steering angle sensor, the steering angle control unit determines the correspondence between the cumulative value of the rotation angle of the steering motor and the steering angle based on the steering angle detection value obtained from the steering angle sensor, and detects the steering angle based on the determined correspondence and the cumulative value of the rotation angle of the steering motor. When an abnormality is detected in the steering angle sensor, the steering angle is detected based on the correspondence determined when no abnormality is detected in the steering angle sensor and the cumulative value of the rotation angle of the steering motor.

13. The autonomous driving assistance device as described in claim 12, characterized in that, The anomaly detection unit detects an anomaly in the rotation angle sensor that measures the rotation angle of the steering motor. When the steering angle control unit detects an anomaly in the rotation angle sensor, it smooths the steering angle detection value obtained by the steering angle sensor to detect the steering angle.

14. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The anomaly detection unit detects anomalies in either the driving state or the surrounding environment, i.e., a state detection anomaly. When the automatic steering control unit detects the abnormal state detection, it infers that an abnormal driving state or surrounding state has been detected based on one or both of the driving state and surrounding state that have not been detected, and calculates the steering angle command value based on the detected or inferred driving state and surrounding state.

15. The autonomous driving assistance device as described in claim 1 or 2, characterized in that, The automatic steering control unit detects vehicle speed, yaw rate, and lateral acceleration as the driving state. The anomaly detection unit detects anomalies in the vehicle speed sensor that detects the vehicle speed, the yaw rate sensor that detects the yaw rate, and the lateral acceleration sensor that detects the lateral acceleration. When no abnormalities are detected in the vehicle speed sensor, yaw rate sensor, and lateral acceleration sensor, the automatic steering control unit calculates the steering angle command value based on the detected values ​​of vehicle speed, yaw rate, and lateral acceleration. When an anomaly is detected in any of the vehicle speed sensor, the yaw rate sensor, and the lateral acceleration sensor, the driving state of the abnormal sensor is inferred based on one or both of the driving state detection value obtained from the normal sensor and the steering angle detection value, and the steering angle command value is calculated based on the driving state detection value obtained from the normal sensor and the inferred driving state value of the abnormal sensor.

16. The autonomous driving assistance device as claimed in claim 15, characterized in that, When the automatic steering control unit detects an anomaly in the yaw rate sensor, it estimates the yaw rate based on the detected steering angle value and the detected vehicle speed value, and calculates the steering angle command value based on the detected vehicle speed value, the estimated yaw rate value, and the detected lateral acceleration value.

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