Steering control unit

Abstract

A steering control device (50) includes: a first calculator (61) configured to calculate a first control quantity for generating an auxiliary force for a motor based on a rotational state; a second calculator (63) configured to calculate a second control quantity for adapting an actual angle to a target angle, the target angle being convertible into a steering wheel rotation angle and generated when the main control device intervenes in steering control; and a third calculator (62) configured to calculate a third control quantity for counteracting the second control quantity based on the rotational state when the main control device intervenes in steering control.

Description

Technical Field

[0001] This invention relates to a steering control device. Background Technology

[0002] For example, the control device in Japanese Unexamined Patent Application Publication No. 2015-20604 performs lane-keeping control to keep the vehicle within its lane and auxiliary control to assist the driver in steering. The control device generates an auxiliary command for generating auxiliary torque based on the steering torque. Further, the control device generates an adaptation command for generating automatic steering torque based on a target angle set by the main control unit. Based on the sum of the auxiliary command and the adaptation command, the control device controls the power supplied to the motor.

[0003] When driver intervention in lane-keeping control is detected, the control unit adjusts the ratio of assist torque to automatic steering torque to be higher at higher levels of intervention. The control unit calculates an intervention coefficient based on the steering torque and adjusts the allowable range of the adaptive command accordingly. As the steering torque value increases, the intervention coefficient gets closer to zero, and the allowable range of the adaptive command becomes narrower. By limiting the adaptive command that counteracts steering intervention, the driver can easily operate the steering wheel. Summary of the Invention

[0004] Recently, customer demands for steering control systems have become increasingly diverse, based on the specifications of the steering control system itself or the specifications of the vehicle to which it is to be equipped. To meet these demands, extensive research and development is underway regarding the configuration of steering control systems.

[0005] This invention can improve the steering feel experienced by the driver when making intervention steering.

[0006] One aspect of the invention is a steering control device. The steering control device controls a motor that serves as a source of auxiliary force for assisting in the rotation of a steering wheel. The steering control device includes: a first calculator configured to calculate a first control quantity for causing the motor to generate auxiliary force based on a rotation state; a second calculator configured to calculate a second control quantity for adapting an actual angle to a target angle, which can be converted into a steering wheel rotation angle and generated when a main control device intervenes in steering control; and a third calculator configured to calculate a third control quantity based on the rotation state when the main control device intervenes in steering control, the third control quantity being used to counteract the second control quantity.

[0007] When the driver turns the steering wheel while the main control unit is intervening in steering control, the deviation between the actual angle and the target angle increases. To eliminate this increased deviation, a second calculator calculates a second control variable with a larger value. Therefore, a torque is generated designed to counteract the deviation between the actual and target angles caused by the driver's steering intervention. This torque may impede the driver's steering. Furthermore, this torque may cause discomfort to the driver.

[0008] In this regard, according to the above configuration, when the driver turns the steering wheel while the main control unit is intervening in steering control, not only a first control quantity based on the turning state but also a third control quantity based on the turning state are calculated. The third control quantity is calculated with the aim of counteracting the second control quantity corresponding to the deviation between the actual angle and the target angle. Therefore, it is unlikely that torque intended to counteract the deviation between the actual angle and the target angle caused by the driver's intervention in steering will be generated. Therefore, even when the main control unit intervenes in steering control, the driver can turn the steering wheel smoothly. This means an improvement in the steering feel experienced by the driver when intervening in steering while the main control unit is intervening in steering control. A new steering control unit with such operating method and effect can be obtained.

[0009] The steering control device may also include a fourth calculator that limits the value of the second control quantity calculated by the second calculator to a predetermined allowable range. This configuration can reduce the possibility that the motor output may become excessive based on the excessively large second control quantity calculated.

[0010] The steering control device may further include: a fifth calculator configured to calculate a fourth control quantity by adding a second control quantity and a third control quantity; and a sixth calculator configured to limit the value of the fourth control quantity calculated by the fifth calculator to a predetermined allowable range.

[0011] When such a configuration is adopted—as described above, to limit the value of the second control quantity calculated by the second calculator to a specified allowable range only for the purpose of reducing the possibility of excessive motor output—the following problem arises.

[0012] When the driver counter-steers the vehicle while it is turning under steering intervention from the main control unit, this results in only the second control input being limited and only the third control input being increased. Conversely, when the driver forward-steers the vehicle while it is turning the vehicle under steering intervention from the main control unit, this does not result in only the second control input being limited and only the third control input being increased. Therefore, the ease of steering may differ between counter-steering and forward-steer.

[0013] In this regard, according to the above configuration, the fourth control quantity obtained by adding the second and third control quantities is limited. In other words, the fourth control quantity, which has a value obtained by canceling out the second control quantity with the third control quantity, is limited. Therefore, when the driver turns the steering wheel in the opposite direction while the vehicle is turning under the intervention of the main control unit's steering control, it is unlikely that only the second control quantity will be limited while only the third control quantity will increase. Therefore, when the driver turns the steering wheel while the vehicle is turning under the intervention of the main control unit's steering control, the steering feel of turning the steering wheel forward and the steering feel of turning the steering wheel in the opposite direction can be almost equivalent. This means an improvement in the steering feel experienced by the driver when intervening in steering while the main control unit is intervening in steering control.

[0014] In the steering control device, the second calculator may include: a feedforward controller configured to calculate a feedforward control quantity by performing feedforward control to adapt the actual angle to the target angle; a proportional controller configured to calculate a first feedback control quantity by performing a proportional operation on the deviation between the actual angle and the target angle, the first feedback control quantity having a value proportional to the deviation; an integral controller configured to calculate a second feedback control quantity by performing an integral operation on the deviation, the second feedback control quantity having a value proportional to the integral value of the deviation; and a derivative controller configured to calculate a third feedback control quantity by performing a derivative operation on the deviation, the third feedback control quantity having... A value proportional to the derivative of the deviation; a first adder configured to calculate a first sum value by adding a feedforward control quantity and a second feedback control quantity; a second adder configured to calculate a second sum value by adding a first feedback control quantity and a third feedback control quantity; a first limit processor configured to limit the first sum value within a specified allowable range; a second limit processor configured to limit the second sum value within a specified allowable range; and a third adder configured to calculate a final second control quantity by adding the first sum value that has been processed by the first limit processor and the second sum value that has been processed by the second limit processor.

[0015] With this configuration, the second control quantity is unlikely to increase when the driver turns the steering wheel while the vehicle is turning under steering control intervention from the main control unit. Furthermore, the final second control quantity can be limited to the value corresponding to the second control quantity calculated when the driver is turning the vehicle under steering control intervention from the main control unit without turning the steering wheel. Therefore, when the driver turns the steering wheel while the vehicle is turning under steering control intervention from the main control unit, the steering feel of forward steering and counter-steering can be almost identical.

[0016] In the steering control device, the second calculator may include: a feedforward controller configured to calculate a feedforward control quantity by performing feedforward control to adapt the actual angle to the target angle; a proportional controller configured to calculate a first feedback control quantity having a value proportional to the deviation between the actual angle and the target angle; an integral controller configured to calculate a second feedback control quantity having a value proportional to the integral value of the deviation by performing an integral operation on the deviation; and a derivative controller configured to calculate a third feedback control quantity by performing a derivative operation on the deviation. The third feedback control quantity has a value proportional to the derivative of the deviation; a first adder configured to calculate a final feedback control quantity by adding the first, second, and third feedback control quantities; a first limit processor configured to limit the feedforward control quantity within a specified allowable range; a second limit processor configured to limit the final feedback control quantity within a specified allowable range; and a second adder configured to calculate a final second control quantity by adding the feedforward control quantity that has passed through the first limit processor and the final feedback control quantity that has passed through the second limit processor.

[0017] With this configuration, the second control quantity is unlikely to increase when the driver turns the steering wheel while the vehicle is turning under steering control intervention from the main control unit. Furthermore, the final second control quantity can be limited to the value corresponding to the second control quantity calculated when the driver is not turning the steering wheel while the vehicle is turning under steering control intervention from the main control unit. Therefore, when the driver turns the steering wheel while the vehicle is turning under steering control intervention from the main control unit, the steering feel of forward steering and counter-steering can be almost identical.

[0018] In the steering control device, the third calculator can be configured to maintain the third control quantity at the value at the point in time when the absolute value of the second control quantity reaches the limit of the specified allowable range, when the absolute value of the second control quantity reaches the limit of the specified allowable range.

[0019] With this configuration, it is unlikely that only the second control variable will be limited while only the third control variable will be increased. Therefore, when the driver turns the steering wheel while the vehicle is turning under the intervention of the main control unit in steering control, the steering feel of turning the steering wheel forward and the steering feel of turning the steering wheel in the opposite direction can be almost identical.

[0020] The steering control device can be configured to adjust the second and third control quantities such that the total value of the second and third control quantities becomes equal to the second control quantity immediately preceding the turning of the steering wheel when the main control device is intervening in the steering control.

[0021] According to the same configuration, when the driver turns the steering wheel while the vehicle is turning under the intervention of the main control unit, the steering feel of turning the steering wheel in the forward direction and the steering feel of turning the steering wheel in the reverse direction can be almost the same.

[0022] In the steering control unit, the second calculator can be configured to set the values ​​of the proportional gain, integral gain, and derivative gain, which are control parameters, to values ​​less than the default values ​​when the main control unit is intervening in the steering control while the steering wheel is turned.

[0023] This configuration reduces the performance required to adapt the actual angle to the target angle. Therefore, when the driver turns the steering wheel while the vehicle is turning under steering control intervention from the main control unit, the difference between the steering feel of forward steering and counter-steering is reduced.

[0024] The steering control device may further include: a steering direction determiner that determines whether the steering wheel is rotating in the opposite direction or in the forward direction based on the steering wheel's rotation direction; and a correction processing unit that corrects a third control quantity calculated by a third calculator to a value less than the original third control quantity corresponding to the rotation state when the steering direction determiner determines that the steering wheel is rotating in the opposite direction.

[0025] With this configuration, when the steering wheel is turned in the opposite direction, the third control quantity is corrected to be less than the original value of the third control quantity corresponding to the turning state. It is unlikely that only the second control quantity will be limited while only the third control quantity will increase. Therefore, when the driver turns the steering wheel while the vehicle is turning under the intervention of the main control unit's steering control, the steering feel of turning the steering wheel forward and in the opposite direction can be almost identical.

[0026] The steering control device of the present invention provides a new steering control device that improves the steering feel experienced by the driver when making intervention steering. Attached Figure Description

[0027] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and in the drawings:

[0028] Figure 1This is a configuration diagram of an electric power steering system according to a first embodiment equipped with a steering control device;

[0029] Figure 2 This is a block diagram of a first embodiment of the steering control device;

[0030] Figure 3 It is a graph illustrating the auxiliary diagram in the first embodiment;

[0031] Figure 4 It is a graph showing the auxiliary correction diagram in the first embodiment;

[0032] Figure 5 This is a schematic diagram. Figure 5 The left image shows the position of the steering wheel when the vehicle is turning left under autonomous driving control; the upper right image shows the steering wheel being turned in the opposite direction by the driver when the vehicle is turning left under autonomous driving control; and the lower right image shows the steering wheel being turned in the forward direction by the driver when the vehicle is turning left under autonomous driving control.

[0033] Figure 6 It is a graph showing the changes of the autonomous driving control quantity, etc., in the first embodiment over time;

[0034] Figure 7 It is a graph showing the relationship between the rotation angle and the steering torque in the first embodiment;

[0035] Figure 8 This is a block diagram of a second embodiment of the steering control device;

[0036] Figure 9 It is a graph showing the relationship between the final autonomous driving control quantity and the limit value of the allowable range of the autonomous driving control quantity in the second embodiment;

[0037] Figure 10 It is a graph showing the relationship between the rotation angle and the steering torque in the second embodiment;

[0038] Figure 11 It is a graph showing the changes of the autonomous driving control quantity, etc., in the second embodiment over time;

[0039] Figure 12 This is a block diagram of the microcomputer in the third embodiment of the steering control device;

[0040] Figure 13 This is a block diagram of the microcomputer in the fourth embodiment of the steering control device;

[0041] Figure 14 It's a line graph. Figure 14The left curve shows the changes of the automatic driving control quantity and the auxiliary correction quantity over time in the case of reverse rotation in the fifth embodiment of the steering control device, and the right curve shows the changes of the automatic driving control quantity and the auxiliary correction quantity over time in the case of forward rotation.

[0042] Figure 15 It's a line graph. Figure 15 The left curve shows the changes of the automatic driving control quantity and the auxiliary correction quantity over time in the case of reverse rotation in the sixth embodiment of the steering control device, and the right curve shows the changes of the automatic driving control quantity and the auxiliary correction quantity over time in the case of forward rotation.

[0043] Figure 16 It's a line graph. Figure 16 The left curve shows the changes in the automatic driving control quantity and the auxiliary correction quantity over time in the case of reverse rotation in the seventh embodiment of the steering control device, and the right curve shows the changes in the automatic driving control quantity and the auxiliary correction quantity over time in the case of forward rotation; and

[0044] Figure 17 This is a block diagram of the microcomputer in the eighth embodiment of the steering control device. Detailed Implementation

[0045] First Implementation Method

[0046] Next, a first embodiment in which the steering control device is implemented as a control device for an electric power steering (EPS) system will be described.

[0047] like Figure 1 As shown, the EPS 10 has a steering shaft 13, a pinion shaft 14, and a rotating shaft 15, which serve as the power transmission path between the steering wheel 11 and the rotating wheel 12. The rotating shaft 15 is located along the width direction of the vehicle. Figure 1 Extending in the left and right directions. Rotating wheels 12 are coupled to both ends of the rotating shaft 15 via tie rods 16. A pinion shaft 14 is positioned to intersect the rotating shaft 15. The pinion teeth 14a of the pinion shaft 14 mesh with the rack teeth 15a of the rotating shaft 15. The rotating shaft 15 moves linearly with the rotation of the steering wheel 11. This linear movement of the rotating shaft 15 is transmitted to the left and right rotating wheels 12 via the tie rods 16, thereby changing the rotation angle θ of the rotating wheels 12. w .

[0048] The EPS 10 has a motor 21 and a reduction gear 22 configured to generate an auxiliary force, which is a force used to assist the driver in steering. The motor 21 serves as an auxiliary motor as the source of the auxiliary force. For example, a three-phase brushless motor is used as the motor 21. The motor 21 is coupled to a pinion shaft 23 via the reduction gear 22. The pinion teeth 23a of the pinion shaft 23 mesh with the rack teeth 15b of the rotating shaft 15. The reduction gear 22 reduces the rotational speed of the motor 21, and the reduced rotational force is transmitted as an auxiliary force to the rotating shaft 15 via the pinion shaft 23. The rotating shaft 15 moves along the vehicle width direction according to the rotation of the motor 21.

[0049] The EPS 10 has a control unit 50. The control unit 50 controls the motor 21 based on the detection results of various sensors. The sensors include a torque sensor 51, a vehicle speed sensor 52, and a rotation angle sensor 53. The torque sensor 51 detects the steering torque T applied to the steering shaft 13 by the rotation of the steering wheel 11. h Vehicle speed sensor 52 detects vehicle speed V. Rotation angle sensor 53 is installed in motor 21. Rotation angle sensor 53 detects the rotation angle θ of motor 21. m The control unit 50 executes the steering torque T by controlling the current applied to the motor 21. h Assisted control that generates auxiliary force. Control device 50 is based on the steering torque T detected by torque sensor 51. h The vehicle speed V detected by vehicle speed sensor 52 and the rotation angle θ detected by rotation angle sensor 53 m To control the power supplied to motor 21.

[0050] Here, some vehicles are equipped with an autonomous driving system. This system implements various driver assistance functions to improve vehicle safety or convenience, or functions as a system to drive the vehicle in place of a driver. In this case, the vehicle is equipped with a host control unit 500, which performs overall control of various on-board system control devices. The host control unit 500 determines the optimal control method based on the vehicle's state at a given time and issues commands according to the determined control method to individually control various on-board control devices.

[0051] The main control unit 500 intervenes in the steering control performed by the control unit 50. The main control unit 500 toggles its automatic driving control function between on (enabled) and off (disabled) by operating a switch (not shown) located in the driver's seat or similar location. The automatic driving control function includes driver assistance control functions designed to enhance vehicle safety or convenience.

[0052] When the autonomous driving control function is activated, the host control unit 500 calculates the target angle θ* as the command value for driving the vehicle in the target lane. The target angle θ*, for example, refers to the rotation angle θ of the motor 21. m pinion angle θ p Or rotation angle θ s The target value, and in this embodiment, the rotation angle θ of the motor 21. m The target value is used as the target angle θ*. Control unit 50 controls motor 21 based on the target angle θ* calculated by host control unit 500. The rotation angle θ of motor 21... m pinion angle θ p and rotation angle θ s It can be converted into the steering wheel 11 rotation angle θ s The rotation angle θ of the rotating wheel 12 w The angle.

[0053] Next, the control device 50 will be described in detail. For example... Figure 2 As shown, the control device 50 includes a microcomputer 50A and a drive circuit 50B. The drive circuit 50B supplies drive power to the motor 21 according to the current command value I* calculated by the microcomputer 50A.

[0054] The microcomputer 50A includes an auxiliary control quantity calculator 61, an auxiliary correction quantity calculator 62, an automatic driving control quantity calculator 63, a limit processing unit 64, and an adder 65. These arithmetic units are functional components implemented by the central processing unit (CPU) of the microcomputer 50A, which executes the control program. However, the implementation of these arithmetic units in software is only an example, and at least some of the arithmetic units can be implemented in hardware, such as logic circuits.

[0055] The auxiliary control quantity calculator 61 is based on the steering torque T detected by the torque sensor 51. h Calculate the auxiliary control quantity I1*. The auxiliary control quantity I1* represents the quantity that should be supplied to motor 21 so that motor 21 responds to the steering torque T. h The amount of current that generates an appropriate auxiliary force. The auxiliary control quantity calculator 61 uses the auxiliary diagram M1 to calculate the auxiliary control quantity I1*. The auxiliary diagram M1 is stored in the storage device of the control device 50.

[0056] like Figure 3 The curve is shown in the figure, and the auxiliary graph M1 is shown in the figure, where the horizontal axis represents the steering torque T. h The graph M1 is a graph where the absolute value of the auxiliary control quantity I1* is represented on the vertical axis, and the auxiliary graph M1 has the following characteristics: as the steering torque T... h As the absolute value of I1 increases, the absolute value of the auxiliary control quantity I1* is set to a larger value.

[0057] The auxiliary control quantity calculator 61 can calculate the auxiliary control quantity I1* based on the vehicle speed V detected by the vehicle speed sensor 52. In this case, the characteristic settings of the auxiliary diagram M1 are as follows: with the steering torque T h As the absolute value of I1* increases and the vehicle speed V decreases, the absolute value of the auxiliary control quantity I1* is set to a larger value.

[0058] The auxiliary correction calculator 62 operates only during the period when the automatic driving control function is activated. The auxiliary correction calculator 62 is based on the steering torque T detected by the torque sensor 51. h Calculate the auxiliary correction amount I2*. The auxiliary correction amount I2* represents the amount that should be applied based on the steering torque T when the driver intervenes in the steering during automatic driving control. h The amount of current that generates an appropriate auxiliary force. That is, the auxiliary correction amount I2* is calculated to counteract the automatic driving control amount I3* (described later) calculated by the automatic driving control amount calculator 63. The auxiliary correction amount calculator 62 uses the auxiliary correction diagram M2 to calculate the auxiliary correction amount I2*. The auxiliary correction diagram M2 is stored in the storage device of the control device 50.

[0059] like Figure 4 As shown in the curve graph, auxiliary correction graph M2 is where the horizontal axis represents the steering torque T. h The graph M2 is a graph where the absolute value of the auxiliary correction amount I2* is represented on the vertical axis, and the auxiliary correction graph M2 has the following characteristics: as the steering torque T... h As the absolute value of the steering torque T increases, the absolute value of the auxiliary correction amount I2* is set to a larger value. h The absolute value of the increase, as the increase in the auxiliary correction amount I2*, is related to the steering torque T. h The slope of the rate of increase gradually decreases.

[0060] like Figure 4 As shown by the double-dotted line in the curve graph, the auxiliary correction graph M2 can have the same characteristics as described above and... Figure 3 The auxiliary graph M1 shown in the curve graph has the same characteristics. The auxiliary correction amount calculator 62 can calculate the auxiliary correction amount I2* by taking into account the vehicle speed V detected by the vehicle speed sensor 52. In this case, the characteristics of the auxiliary correction graph M2 are set as follows: with the steering torque T h As the absolute value of I2* increases and the vehicle speed V decreases, the absolute value of the auxiliary correction amount is set to a larger value.

[0061] The autonomous driving control calculator 63 operates only during the period when the autonomous driving control function is activated. The autonomous driving control calculator 63 receives the target angle θ* calculated by the host control unit 500 and the rotation angle θ of the motor 21 detected by the rotation angle sensor 53. m The automatic driving control quantity calculator 63 executes the rotation angle θ of the motor 21. m The feedback control adapted to the target angle θ* is used to calculate the autonomous driving control quantity I3*. The autonomous driving control quantity calculator 63 calculates, for example, the rotation angle θ of motor 21. m The deviation from the target angle θ* is Δθ(=θ*-θ) m The system performs proportional, integral, and derivative operations on the calculated deviation Δθ to calculate the automatic driving control quantity I3*. Therefore, the automatic driving control quantity I3* is the sum of the output values ​​of the proportional, integral, and derivative elements using the deviation Δθ as input. The automatic driving control quantity I3* represents the amount that should be supplied to motor 21 to cause motor 21 to generate a rotation angle θ for motor 21. m The amount of current adapted to the torque at the target angle θ*.

[0062] The limitation processing unit 64 performs limitation processing to limit the value of the autonomous driving control quantity I3* calculated by the autonomous driving control quantity calculator 63 to a value within a specified allowable range. When the absolute value of the autonomous driving control quantity I3* calculated by the autonomous driving control quantity calculator 63 exceeds the limit value of the allowable range, the value of the autonomous driving control quantity I3* is limited to the limit value. If the driving control quantity I3* has a positive value, then when the value of the autonomous driving control quantity I3* exceeds the positive limit value, the value of the autonomous driving control quantity I3* is limited to the positive limit value. If the autonomous driving control quantity I3* has a negative value, then when the value of the autonomous driving control quantity I3* exceeds the negative limit value, the value of the autonomous driving control quantity I3* is limited to the negative limit value. Therefore, the motor 21 is unlikely to generate excessive torque based on an excessively large autonomous driving control quantity I3* that exceeds the limit value of the allowable range.

[0063] Adder 65 calculates the current command value I* for motor 21 by adding the auxiliary control quantity I1*, the auxiliary correction quantity I2*, and the automatic driving control quantity I3*. Therefore, the first embodiment can produce the following effects.

[0064] When the driver intervenes in steering during the execution of automatic driving control, not only is the steering torque T calculated... h The auxiliary control quantity I1* is calculated based on the steering torque T. hThe auxiliary correction amount I2* is calculated. Therefore, the motor 21 generates an auxiliary force based on the current value obtained by adding the auxiliary control amount I1* and the auxiliary correction amount I2*. That is, the motor 21 generates an auxiliary force that is larger than the auxiliary correction amount I2* during normal manual operation when the automatic driving control function is off. Furthermore, the auxiliary correction amount I2* is calculated to counteract the automatic driving control amount I3*. Therefore, even during automatic driving control, the driver can smoothly operate the steering wheel 11. In other words, the driver is allowed to intervene in steering during automatic driving control, and the steering feel experienced by the driver when intervening in steering can be improved. A new control device 50 with such operating mode and effect can be obtained.

[0065] In a hands-free autonomous driving control scenario assuming the driver removes his or her hands from the steering wheel 11, to ensure line-following performance, for example, the control device 50 can calculate an autonomous driving control amount I3* with a larger absolute value relative to the target angle θ*, and the control device 50 can have higher feedback performance. Under this assumption, the control device 50 of this embodiment is particularly preferred because it adds the auxiliary correction amount I2* used to counteract the autonomous driving control amount I3* to the auxiliary control amount I1* used to perform normal auxiliary control, thereby improving the steering feel experienced by the driver when intervening in steering during autonomous driving control.

[0066] Second Implementation Method

[0067] Next, a second embodiment in which the steering control device is implemented as an EPS control device will be described. In the first embodiment described above, there is a problem that when the driver intervenes in steering while the vehicle is turning under automatic driving control, the driver may feel discomfort due to the difference in steering feel between turning the steering wheel 11 in the forward direction and turning it in the reverse direction.

[0068] "Forward rotation" refers to a rotational state in which the driver applies torque to the steering wheel 11 in the same direction as the direction the driver is turning the steering wheel 11 via automatic steering. "Reverse rotation" refers to a rotational state in which the driver applies torque to the steering wheel 11 in the opposite direction to the direction the driver is turning the steering wheel 11 via automatic steering.

[0069] like Figure 5 As shown, for example, when the vehicle is turning left under autonomous driving control and the driver turns the steering wheel 11 in the opposite direction, the rotation angle θ of the motor 21 is... mThe deviation from the target angle θ* increases in the direction opposite to the vehicle's rotation direction (in this case, to the right). Therefore, the automatic driving control quantity calculator 63 calculates the automatic driving control quantity I3* to offset the increased deviation. The automatic driving control quantity I3* calculated in this case aims to reduce the rotation angle θ of the motor 21. m The rotation angle θ of motor 21 is restored in the positive rotation direction. m The amount exceeding the target angle θ* in the reverse rotation direction. Therefore, calculate the autonomous driving control quantity I3* with the same sign as the current autonomous driving control quantity I3*. Therefore, with the rotation angle θ of motor 21 m As the deviation from the target angle θ* increases, the absolute value of the autonomous driving control quantity I3* increases and eventually becomes as follows: Figure 6 The solid line in the curve graph shows that it is restricted by the restricted processing unit 64.

[0070] Meanwhile, the auxiliary correction calculator 62 calculates the absolute value of the amount of reverse rotation (i.e., steering torque T) based on the aforementioned auxiliary correction diagram M2. h The auxiliary correction amount I2* becomes larger as the absolute value of the variable increases. Since the value of the automatic driving control amount I3* is limited here, therefore... Figure 6 As shown by the broken line in the graph, a situation arises where only the auxiliary correction amount I2* increases due to the reverse rotation. Therefore, during automatic driving, the driver is allowed to intervene in the steering smoothly, and as a measure of ease of steering, the driver feels the steering wheel is lighter.

[0071] like Figure 5 As shown, for example, when the vehicle is turning left under autonomous driving control and the driver is turning the steering wheel 11 in the same direction, the rotation angle θ of the motor 21 is... m The deviation from the target angle θ* increases in the same direction as the vehicle's rotation (here, to the left). Therefore, the automatic driving control quantity calculator 63 calculates the automatic driving control quantity I3* to offset the increased deviation. The automatic driving control quantity I3* calculated in this case aims to reduce the rotation angle θ of the motor 21. m The rotation angle θ of motor 21 is restored in the reverse rotation direction. m The amount exceeding the target angle θ* in the positive rotation direction. Therefore, calculate the autonomous driving control quantity I3* with the opposite sign to the current autonomous driving control quantity I3*. Therefore, the absolute value of the autonomous driving control quantity I3* is unlikely to respond to the rotation angle θ of motor 21. m It increases with the increase of the deviation from the target angle θ*. That is to say, as... Figure 6 As shown by the solid line in the graph, during forward rotation, the absolute value of the autonomous driving control quantity I3* is unlikely to reach the limit of the allowable range, and the autonomous driving control quantity I3* is unlikely to be limited by the limiting processing unit 64.

[0072] The auxiliary correction calculator 62 calculates the steering torque T based on the auxiliary correction diagram M2 mentioned above. h The corresponding auxiliary correction amount I2*. Here, the value of the autonomous driving control amount I3* is unrestricted. Therefore, as... Figure 6 As shown by the broken line in the curve, there is no situation where only the auxiliary correction amount I2* increases due to reverse rotation. Therefore, although the driver is allowed to intervene smoothly in steering during automatic driving, the driver feels that the steering wheel 11 is heavier as a result of the ease of steering through the steering wheel 11 than when the steering wheel 11 is turned in the opposite direction.

[0073] Specifically, such as Figure 7 As shown in the curve, with the target rotation angle θ s *Based on the steering torque T h The absolute value relative to the rotation angle θ s The characteristics of the change differ between forward and reverse rotation. Target rotation angle θ s * refers to the rotation angle θ of motor 21. m The rotation angle of steering wheel 11 when matched with the target angle θ*. More specifically, the steering torque T during reverse rotation. h The maximum absolute value is less than the steering torque T during forward rotation. h The maximum absolute value. Therefore, when the driver intervenes to steer while the vehicle is turning under autonomous driving control, the steering feel experienced by the driver, as a measure of the ease of steering through the steering wheel 11, differs between forward and reverse steering.

[0074] Furthermore, when the vehicle is turning right under autonomous driving control while simultaneously turning the steering wheel 11 in both the forward and reverse directions, the steering feel is different between turning the steering wheel in the forward and reverse directions, just as it is when the vehicle is turning left under autonomous driving control while simultaneously turning the steering wheel 11 in both the forward and reverse directions.

[0075] To eliminate the discomfort felt by the driver when intervening in steering during automatic driving control, the control device 50 is configured as follows in this embodiment: Figure 8 As shown, the microcomputer 50A has an adder 66 and a limit processing unit 67. The adder 66 calculates the final automatic driving control quantity I4* by adding the auxiliary correction quantity I2* calculated by the auxiliary correction quantity calculator 62 and the automatic driving control quantity I3* calculated by the automatic driving control quantity calculator 63.

[0076] The limiting processing unit 67 limits the final automatic driving control quantity I4* calculated by the adder 66 to a value within a specified allowable range. When the value of the final automatic driving control quantity I4* calculated by the adder 66 is within the allowable range, the final automatic driving control quantity I4* calculated by the adder 66 is used to control the motor 21 as is.

[0077] Next, the operation of this implementation method will be described. For example... Figure 5 As shown, for example, when the vehicle is turning left under autonomous driving control and the driver turns the steering wheel 11 in the opposite direction, the rotation angle θ of the motor 21 is... m The deviation from the target angle θ* increases in the direction opposite to the vehicle's rotation direction. Therefore, the automatic driving control quantity calculator 63 calculates the automatic driving control quantity I3* to offset the increased deviation. The automatic driving control quantity I3* calculated in this case aims to reduce the rotation angle θ of the motor 21. m The rotation angle θ of motor 21 is restored in the positive rotation direction. m The amount exceeding the target angle θ* in the reverse rotation direction. Therefore, calculate the autonomous driving control quantity I3* with the same sign as the current autonomous driving control quantity I3*. Therefore, with the rotation angle θ of motor 21 m As the deviation from the target angle θ* increases, the absolute value of the autonomous driving control quantity I3* increases.

[0078] Meanwhile, the auxiliary correction calculator 62 calculates the absolute value of the amount of reverse rotation (i.e., steering torque T) based on the aforementioned auxiliary correction diagram M2. h The auxiliary correction amount I2* increases with the increase of the absolute value of the automatic control quantity (I1*). Here, the auxiliary correction amount I2* has the same sign as the auxiliary control quantity I1* calculated by the auxiliary control quantity calculator 61. The auxiliary correction amount I2* is calculated for the purpose of offsetting the automatic control quantity I3* calculated by the automatic control quantity calculator 63. Therefore, the sign of the auxiliary correction amount I2* is opposite to the sign of the automatic control quantity I3* calculated by the automatic control quantity calculator 63.

[0079] Therefore, as Figure 9 As shown in the graph, even when the absolute value of the autonomous driving control quantity I3* calculated by the autonomous driving control quantity calculator 63 exceeds the limit of the allowable range, the absolute value of the final autonomous driving control quantity I4* calculated by the adder 66 is within the allowable range. This is because the autonomous driving control quantity I3* calculated by the autonomous driving control quantity calculator 63 is canceled out by the auxiliary correction quantity I2* calculated by the auxiliary correction quantity calculator 62. Therefore, as Figure 10As shown by the solid line in the graph, even when the absolute value of the autonomous driving control quantity I3* calculated by the autonomous driving control quantity calculator 63 exceeds the limit of the allowable range, the value of the autonomous driving control quantity I3* is not restricted.

[0080] Although the auxiliary correction calculator 62 calculates the amount of reverse rotation (i.e., steering torque T) based on the auxiliary correction diagram M2 above, h The auxiliary correction amount I2* is used, but here, the value of the autonomous driving control amount I3* can be considered unrestricted. Therefore, as Figure 10 As shown by the broken line in the curve, there will not be a situation where only the auxiliary correction amount I2* increases with the increase of the reverse rotation amount. The absolute value of the automatic driving control amount I3* also depends on the reverse rotation amount (i.e., the rotation angle θ of motor 21). m The deviation from the target angle θ* increases. Therefore, the relationship between the value of the auxiliary correction amount I2* and the value of the automatic driving control amount I3* remains the original relationship where the value of the automatic driving control amount I3* is unrestricted.

[0081] like Figure 5 As shown, for example, when the vehicle is turning left under autonomous driving control and the driver is turning the steering wheel 11 forward in the same direction, an autonomous driving control quantity I3* with the opposite sign to the current autonomous driving control quantity I3* is calculated. Therefore, during forward turning, the absolute value of the autonomous driving control quantity I3* is unlikely to respond to the rotation angle θ of the motor 21. m It increases with the increase of the deviation from the target angle θ*, and as... Figure 10 As shown by the solid line in the graph, the autonomous driving control quantity I3* is unlikely to be limited.

[0082] Meanwhile, the auxiliary correction calculator 62 calculates the amount of steering torque T based on the aforementioned auxiliary correction diagram M2. h The corresponding auxiliary correction amount I2*. Since the value of the automatic driving control amount I3* is unrestricted here, therefore... Figure 10 As shown by the broken line in the curve, there will be no situation where only the auxiliary correction amount I2* increases due to reverse rotation. The absolute value of the automatic driving control amount I3* is also based on the amount of reverse rotation (i.e., steering torque T). h Therefore, during autonomous driving, the driver is allowed to smoothly intervene in the steering, and as a result of the ease with which the steering wheel 11 is turned, the same steering feel can be experienced as when the steering wheel 11 is turned in the opposite direction.

[0083] like Figure 11 As shown in the curve, with the target rotation angle θ s *Based on the steering torque T h The absolute value relative to the rotation angle θ sThe characteristics of the change in steering torque T are essentially the same during forward and reverse rotation. More specifically, the steering torque T during reverse rotation... h The maximum absolute value is basically equal to the steering torque T during forward rotation. h The maximum absolute value. Therefore, when the driver intervenes to steer while the vehicle is turning under autonomous driving control, the steering feel experienced by the driver, as a degree of ease of steering through the steering wheel 11, is essentially the same during both forward and reverse steering.

[0084] Therefore, in addition to the effects (1) of the first embodiment described above, the second embodiment can also produce the following effects. The adder 66 calculates the final autonomous driving control amount I4* by adding the auxiliary correction amount I2* and the autonomous driving control amount I3*, and this final autonomous driving control amount I4* is limited to a value within a specified allowable range. Therefore, it is unlikely that only the autonomous driving control amount I3* will be limited while only the auxiliary correction amount I2* will increase. Therefore, when the driver intervenes to steer while the vehicle is turning under autonomous driving control, the steering feel of turning the steering wheel forward and the steering feel of turning it backward are almost identical. This means an improvement in the steering feel experienced by the driver when intervening to steer during autonomous driving control.

[0085] Third Implementation Method

[0086] Next, a third embodiment in which the steering control device is implemented as an EPS control device will be described. This embodiment differs from the first embodiment described above in the configuration of the microcomputer 50A.

[0087] like Figure 12 As shown, the autonomous driving control quantity calculator 63 has a subtractor 71, a feedforward controller 72, a proportional controller 73, an integral controller 74, a derivative controller 75, three adders 76, 77, and 78, and two limit processors 79A and 79B.

[0088] Subtractor 71 calculates the rotation angle θ of motor 21 detected by rotation angle sensor 53. m The deviation Δθ from the target angle θ* calculated by the host control unit 500 is (=θ*-θ) m The feedforward controller 72 is configured to compensate for the response delay caused by the inertia of the EPS 10 and to increase control responsiveness. The feedforward controller 72 calculates the target angular acceleration α(=d) by performing a second-order derivative with respect to the target angle θ*. 2 θ* / dt 2The feedforward control quantity I5*(=J·α) is calculated as the inertia compensation value by multiplying the calculated target angular acceleration α by the inertia J of EPS 10. The inertia J is obtained, for example, from the physical model of EPS 10.

[0089] The proportional controller 73 calculates a first feedback control quantity I6* by performing a proportional operation on the deviation Δθ calculated by the subtractor 71. This first feedback control quantity I6* has a value proportional to the deviation Δθ. The integral controller 74 calculates a second feedback control quantity I7* by performing an integral operation on the deviation Δθ calculated by the subtractor 71. This second feedback control quantity I7* has a value proportional to the integral value of the deviation Δθ. When the driver intervenes with steering during automatic driving control, the integral controller 74 stops the integral operation.

[0090] The differential controller 75 calculates a third feedback control quantity I8* by performing a differential operation on the deviation Δθ calculated by the subtractor 71. The third feedback control quantity I8* has a value that is proportional to the differential value of the deviation Δθ.

[0091] Adder 76 calculates the first autonomous driving control quantity I9* by adding the feedforward control quantity I5* calculated by feedforward controller 72 and the second feedback control quantity I7* calculated by integral controller 74.

[0092] Adder 77 calculates the second autonomous driving control quantity I by adding the first feedback control quantity I6* calculated by proportional controller 73 and the third feedback control quantity I8* calculated by differential controller 75. 10 *

[0093] Limit processor 79A restricts the first autonomous driving control quantity I9* calculated by adder 76 to a value within a specified allowable range. Limit processor 79B restricts the second autonomous driving control quantity I calculated by adder 77. 10 *The value is limited to a specified allowable range. These allowable ranges are set, for example, with reference to the autonomous driving control quantity I3* calculated when performing autonomous driving control assuming no manual driving is required.

[0094] Adder 78 combines the first autonomous driving control quantity I9*, which has already been processed by limit processor 79A, and the second autonomous driving control quantity I, which has already been processed by limit processor 79B. 10 *The final autonomous driving control quantity I3 is calculated by adding them together.*

[0095] Therefore, the third embodiment can produce the following effects: the first autonomous driving control quantity I9* is the sum of the feedforward control quantity I5* and the second feedback control quantity I7*, and the second autonomous driving control quantity I is the sum of the first feedback control quantity I6* and the third feedback control quantity I8*.10 Each of the values ​​in * is limited to a specified permissible range. Using the first automated driving control quantity I9* and the second automated driving control quantity I... 10 The sum of the values ​​of * is used as the final autonomous driving control quantity I3* when controlling motor 21. Therefore, the autonomous driving control quantity I3* is unlikely to increase due to steering intervention. Furthermore, the final autonomous driving control quantity I3* can be limited to the value corresponding to the autonomous driving control quantity I3* calculated when performing autonomous driving control under the assumption of no manual driving. Therefore, when the driver intervenes to steer while the vehicle is turning under autonomous driving control, the steering feel of turning the steering wheel forward and the steering feel of turning the steering wheel in the opposite direction are almost equivalent. This means an improvement in the steering feel experienced by the driver when intervening to steer during the execution of autonomous driving control.

[0096] Fourth Implementation Method

[0097] Next, a fourth embodiment in which the steering control device is implemented as an EPS control device will be described. This embodiment differs from the third embodiment described above in the configuration of the automatic driving control quantity calculator 63.

[0098] like Figure 13 As shown, in addition to subtractor 71, feedforward controller 72, proportional controller 73, integral controller 74, derivative controller 75, adder 78 and two limit processors 79A and 79B, the automatic driving control quantity calculator 63 also has adder 81.

[0099] Adder 81 calculates the final feedback control quantity I by adding the first feedback control quantity I6* calculated by proportional controller 73, the second feedback control quantity I7* calculated by integral controller 74, and the third feedback control quantity I8* calculated by derivative controller 75. 11 *

[0100] Limit processor 79A restricts the feedforward control quantity I5* calculated by feedforward controller 72 to a value within a specified allowable range. Limit processor 79B restricts the final feedback control quantity I calculated by adder 81. 11 *Restricted to values ​​within the specified allowed range.

[0101] Adder 78 uses the feedforward control quantity I5* that has been limited by processor 79A and the feedback control quantity I that has been limited by processor 79B. 11 *The control quantity I3 for autonomous driving is calculated by adding them together.*

[0102] Therefore, the fourth embodiment can produce the following effect: the feedforward control quantity I5* calculated by the feedforward controller 72 and the final feedback control quantity I calculated by the adder 81. 11Each of the values ​​in * is limited to a specified allowable range. The restricted feedforward control variable I5* and feedback control variable I are used. 11 The sum of the values ​​of * is used as the final autonomous driving control quantity I3* when controlling motor 21. Therefore, the autonomous driving control quantity I3* is unlikely to increase due to steering intervention. Furthermore, the final autonomous driving control quantity I3* can be limited to the value corresponding to the autonomous driving control quantity I3* calculated when performing autonomous driving control under the assumption of no manual driving. Therefore, when the driver intervenes to steer while the vehicle is turning under autonomous driving control, the steering feel of turning the steering wheel forward and the steering feel of turning the steering wheel in the opposite direction are almost equivalent. This means an improvement in the steering feel experienced by the driver when intervening to steer during the execution of autonomous driving control.

[0103] Fifth Implementation Method

[0104] Next, a fifth embodiment in which the steering control device is implemented as an EPS control device will be described. This embodiment differs from the first embodiment described above in terms of the processing executed by the microcomputer 50A.

[0105] like Figure 14 As shown by the real characteristic line in the left curve diagram, when the vehicle is turning left under automatic driving control and the driver turns the steering wheel 11 in the opposite direction (time T1), with the rotation angle θ of the motor 21... m As the deviation from the target angle θ* increases, the absolute value of the autonomous driving control quantity I3* may reach the limit of the allowable range and be restricted by the limiting processing unit 64. Simultaneously, with the increase in the reverse rotation amount (i.e., steering torque T)... h As the absolute value of the auxiliary correction I2* increases, the absolute value of the auxiliary correction I2* also becomes larger. This could lead to a situation where only the auxiliary correction I2* increases due to the reverse rotation.

[0106] As a countermeasure, when the absolute value of the automatic driving control quantity I3* reaches the limit value of the allowable range (e.g., the positive limit value), the microcomputer 50A performs the following processing.

[0107] like Figure 14 As shown by the broken characteristic line in the left curve diagram, when the absolute value of the automatic driving control quantity I3* reaches the limit of the allowable range (time T2), the microcomputer 50A will maintain the auxiliary correction quantity I2* calculated by the auxiliary correction quantity calculator 62 at the value at that point in time when the absolute value of the automatic driving control quantity I3* reaches the limit of the allowable range. Therefore, it is unlikely that the steering torque T will change. hThe case where only the auxiliary correction amount I2* increases due to the increase in reverse rotation. The absolute value of the maintained auxiliary correction amount I2* here is equal to the absolute value of the increase in the automatic driving control amount I3* due to the reverse rotation. Therefore, the total value obtained by adding the restricted automatic driving control amount I3* and the maintained auxiliary correction amount I2* (=I2*+I3*) is as follows.

[0108] like Figure 14 As shown by the dashed feature line in the left curve diagram, the total value of the automatic driving control quantity I3* and the auxiliary correction quantity I2* is equal to the value of the automatic driving control quantity I3* before the time T1 when the driver turns the steering wheel 11 in the opposite direction.

[0109] like Figure 14 As shown by the real characteristic line in the right curve diagram, similarly, when the vehicle is turning left under automatic driving control and the driver is turning the steering wheel 11 in the same direction (time T3), the absolute value of the automatic driving control quantity I3* may be limited by the limiting processing unit 64. Therefore, also during forward turning, only the auxiliary correction quantity I2* may increase. As a countermeasure, when the absolute value of the automatic driving control quantity I3* reaches the limit value of the allowable range (e.g., a negative limit value), the microcomputer 50A performs the following processing.

[0110] like Figure 14 As shown by the broken characteristic line in the right curve graph, when the absolute value of the automatic driving control quantity I3* reaches the limit of the allowable range (time T4), the microcomputer 50A will maintain the auxiliary correction quantity I2* calculated by the auxiliary correction quantity calculator 62 at the value at the time point when the absolute value of the automatic driving control quantity I3* reaches the limit of the allowable range. Therefore, it is unlikely that the steering torque T will change. h This is due to an increase in forward rotation, but only the auxiliary correction amount I2* increases. The absolute value of the maintained auxiliary correction amount I2* here is equal to the absolute value of the increase in the automatic driving control amount I3* due to forward rotation. Therefore, the total value obtained by adding the restricted automatic driving control amount I3* and the maintained auxiliary correction amount I2* (=I2*+I3*) is as follows.

[0111] like Figure 14 As shown by the dashed feature line in the right curve diagram, the total value of the automatic driving control quantity I3* and the auxiliary correction quantity I2* is equal to the value of the automatic driving control quantity I3* before the time T3 when the driver turns the steering wheel 11 in the opposite direction.

[0112] The situation where the vehicle is turning right under autonomous driving control while simultaneously turning the steering wheel 11 in both the forward and reverse directions is the same as the situation where the vehicle is turning left under autonomous driving control while simultaneously turning the steering wheel 11 in both the forward and reverse directions.

[0113] Therefore, the fifth embodiment can produce the following effect: when the absolute value of the autonomous driving control quantity I3* reaches the limit of the allowable range due to driver intervention steering during the execution of autonomous driving control, the auxiliary correction quantity I2* remains at the value at the point in time when the absolute value of the autonomous driving control quantity I3* reaches the limit of the allowable range. Therefore, it is unlikely that only the autonomous driving control quantity I3* will be limited while only the auxiliary correction quantity I2* increases. Therefore, when the driver intervenes steering while the vehicle is turning under autonomous driving control, the steering feel of turning the steering wheel forward and the steering feel of turning the steering wheel backward are almost equivalent. This means an improvement in the steering feel experienced by the driver when intervening in steering during the execution of autonomous driving control.

[0114] Sixth Implementation Method

[0115] Next, a sixth embodiment in which the steering control device is implemented as an EPS control device will be described. This embodiment differs from the first embodiment described above in terms of the processing executed by the microcomputer 50A.

[0116] The microcomputer 50A has the function of determining intentional intervention by the driver in steering during the execution of automatic driving control. The microcomputer 50A, for example, bases its determination on the steering torque T detected by the torque sensor 51. h To determine the driver's intervention in steering.

[0117] like Figure 15 As shown in the left curve diagram, when the vehicle is turning left under automatic driving control and the driver turns the steering wheel 11 in the opposite direction (time T5), it is determined that the steering wheel 11 is being turned in the opposite direction (time T6), which triggers the execution of the following process.

[0118] Each of the values ​​of the automatic driving control quantity I3* and the auxiliary correction quantity I2* is held at a predetermined value, such that the total value of the auxiliary correction quantity I2* and the automatic driving control quantity I3* (=I2*+I3*) becomes equal to the value of the automatic driving control quantity I3* before the time T5 when the driver turns the steering wheel 11 in the opposite direction.

[0119] like Figure 15 As shown in the right curve diagram, when the vehicle is turning right under automatic driving control and the driver is turning the steering wheel 11 in the same direction (time T7), it is determined that the steering wheel 11 is being turned in the forward direction (time T8), which triggers the execution of the following process.

[0120] Each of the values ​​of the automatic driving control quantity I3* and the auxiliary correction quantity I2* is adjusted to a predetermined value and held at the adjusted value, such that the total value of the auxiliary correction quantity I2* and the automatic driving control quantity I3* (=I2*+I3*) becomes equal to the value of the automatic driving control quantity I3* immediately before the time T7 when the driver turns the steering wheel 11 in the forward direction.

[0121] Therefore, the sixth embodiment can produce the following effect: when it is determined that the driver is intervening in steering during the execution of autonomous driving control, the total value of the assist correction amount I2* and the autonomous driving control amount I3* is maintained at a value equal to the value of the autonomous driving control amount I3* immediately before the driver intervenes in steering. For example, when performing autonomous driving control assuming no manual driving is required, the vehicle maintains balance with driving resistance. The autonomous driving control amount I3* has a value that maintains balance with driving resistance. Therefore, when the driver intervenes in steering while the vehicle is turning under autonomous driving control, maintaining the total value of the assist correction amount I2* and the autonomous driving control amount I3* at a value equal to the value of the autonomous driving control amount I3* immediately before the driver intervenes in steering can make the steering feel of turning the steering wheel forward and the steering feel of turning the steering wheel backward almost identical. This means an improvement in the steering feel experienced by the driver when intervening in steering during the execution of autonomous driving control.

[0122] Seventh Implementation Method

[0123] Next, a seventh embodiment in which the steering control device is implemented as an EPS control device will be described. This embodiment differs from the first embodiment described above in terms of the processing executed by the microcomputer 50A.

[0124] The microcomputer 50A has the function of determining intentional intervention by the driver in steering during the execution of automatic driving control. The microcomputer 50A, for example, bases its determination on the steering torque T detected by the torque sensor 51. h This is used to determine driver intervention in steering. When the driver turns the steering wheel 11 during automatic driving control, the microcomputer 50A sets the PID gain (proportional gain, integral gain, and derivative gain), which are control parameters for PID control, to a value lower than the default value. Therefore, the performance of the PID control adapted to the target value is reduced.

[0125] like Figure 16 As shown in the left curve diagram, when the vehicle is turning left under autonomous driving control and the driver turns the steering wheel 11 in the opposite direction (time T9), with the rotation angle θ of the motor 21... mAs the deviation from the target angle θ* increases, the absolute value of the autonomous driving control quantity I3* increases. Here, during the period when the driver is turning the steering wheel 11 while autonomous driving control is being executed, the PID gain is set to a value less than the default value. As the performance of the PID control adapted to the target angle θ* decreases, the absolute value of the autonomous driving control quantity I3* is unlikely to increase.

[0126] like Figure 16 As shown in the right curve, when the vehicle is turning right under autonomous driving control and the driver is turning the steering wheel 11 in the same direction (time T10), as in the case of turning in the opposite direction, the performance of the PID control adapted to the target angle θ* is reduced, making it unlikely that the absolute value of the autonomous driving control quantity I3* will increase.

[0127] Therefore, in addition to the effects of the first embodiment described above, the seventh embodiment can also produce the following effect: during the time when the driver is intervening in steering while performing automatic driving control, the PID gain is set to a value less than the default value. This is because the actual rotation angle θ is adjusted during PID control. m With reduced performance adapting to the target angle θ*, the absolute value of the autonomous driving control quantity I3* is unlikely to increase. When the driver intervenes to steer while the vehicle is turning under autonomous driving control, the difference between the steering feel of forward steering and counter-steering feels decreases. This implies an improvement in the steering feel experienced by the driver when intervening to steer during autonomous driving control.

[0128] Eighth Implementation Method

[0129] Next, an eighth embodiment in which the steering control device is implemented as an EPS control device will be described. This embodiment differs from the first embodiment described above in the configuration of the microcomputer 50A.

[0130] like Figure 17 As shown, in addition to the auxiliary control quantity calculator 61, auxiliary correction quantity calculator 62, automatic driving control quantity calculator 63, limit processing unit 64, and adder 65, the microcomputer 50A also has a rotation direction determiner 91 and a gain multiplication unit 92.

[0131] The steering direction determiner 91 is based, for example, on the steering torque T detected by the torque sensor 51. hThe steering direction of the steering wheel 11 is determined by referencing its neutral position. The steering direction determiner 91 determines whether the steering wheel 11 is rotating in the reverse or forward direction, and sets the value of flag F based on the determination result. When the steering direction determiner 91 determines that the steering wheel 11 is rotating in the reverse direction, it sets the value of flag F to "1". When the steering direction determiner 91 determines that the steering wheel 11 is rotating in the forward direction, it sets the value of flag F to "0".

[0132] The gain multiplication unit 92 receives the value of the flag F set by the rotation direction determiner 91. The gain multiplication unit 92 multiplies the auxiliary correction amount I2* calculated by the auxiliary correction amount calculator 62 by the gain G. The gain multiplication unit 92 changes the value of the gain G according to the value of the flag F. When the value of the flag F is "1", the gain multiplication unit 92 sets the gain G to a value less than "1". This is based on reducing the auxiliary correction amount I2*. When the value of the flag F is "0", the gain multiplication unit 92 sets the gain G to "1".

[0133] In addition to the same subtractor 71, feedforward controller 72, proportional controller 73, integral controller 74, and derivative controller 75 as those in the third embodiment described above, the autonomous driving control quantity calculator 63 also has an adder 93. The adder 93 calculates the autonomous driving control quantity I3* by adding the feedforward control quantity I5* calculated by the feedforward controller 72, the first feedback control quantity I6* calculated by the proportional controller 73, the second feedback control quantity I7* calculated by the integral controller 74, and the third feedback control quantity I8* calculated by the derivative controller 75.

[0134] During a reverse rotation, which may result in only the automatic control amount I3* being limited while only the auxiliary correction amount I2* increases, the auxiliary correction amount I2* calculated by the auxiliary correction amount calculator 62 is multiplied by a gain G having a value less than "1". Therefore, the final auxiliary correction amount I2* used to control the motor 21 has a value less than that of the steering torque T. h The corresponding value of the original auxiliary correction I2*.

[0135] Therefore, the eighth embodiment can produce the following effect: when the steering wheel 11 is in a reverse rotation state, the auxiliary correction amount I2* calculated by the auxiliary correction amount calculator 62 is corrected to be less than the steering torque T. hThe corresponding value of the original auxiliary correction amount I2*. Therefore, during reverse steering, it is unlikely that only the autonomous driving control amount I3* will be limited while only the auxiliary correction amount I2* will increase. Thus, when the driver intervenes to steer while the vehicle is turning under autonomous driving control, the steering feel of turning the steering wheel forward and backward is almost identical. This implies an improvement in steering feel experienced by the driver when intervening to steer during autonomous driving control.

[0136] Other implementation methods

[0137] Each of the embodiments can be implemented by the following modifications. In the embodiments, the type of EPS 10 that applies auxiliary force to the rotation shaft 15 has been described as an example of the application of the control device 50. However, the control device 50 can be applied to the type of EPS that applies auxiliary force to the steering shaft 13. Figure 1 As shown by the double-dotted line, motor 21 is coupled to steering shaft 13, for example, via reduction gear 22. Pinion shaft 23 can be omitted.

[0138] Other technical ideas

[0139] Next, the technical concept as understood from the implementation method will be described further. The target angle is the rotation angle (θ) of the motor. m ), pinion angle (θ) p (It is the rotation angle of the pinion shaft meshing with the rotating shaft) or rotation angle (θ) s (The target value is the rotation angle of the steering wheel).

Claims

1. A steering control device (50) that controls a motor as a source of auxiliary force for assisting in turning a steering wheel, said steering control device (50) being characterized in that it comprises: A first calculator (61) is configured to calculate a first control quantity for causing the motor to generate the auxiliary force based on the rotation state; The second calculator (63) is configured to calculate a second control quantity for adapting the actual angle to the target angle, which can be converted into the rotation angle of the steering wheel and generated when the main control unit intervenes in the steering control; A third calculator (62) is configured to calculate a third control quantity to counteract the second control quantity based on the rotation state when the host control device intervenes in the steering control. The fifth calculator (66) is configured to calculate the fourth control quantity by adding the second control quantity and the third control quantity; as well as The sixth calculator (67) is configured to limit the value of the fourth control quantity calculated by the fifth calculator (66) to a specified allowable range.

2. The steering control device (50) according to claim 1, characterized in that, The second calculator (63) includes: A feedforward controller (72) is configured to calculate a feedforward control quantity by performing feedforward control to adapt the actual angle to the target angle; A proportional controller (73) is configured to calculate a first feedback control quantity by performing a proportional operation on the deviation between the actual angle and the target angle, the first feedback control quantity having a value proportional to the deviation; An integral controller (74) is configured to calculate a second feedback control quantity by performing an integral operation on the deviation, the second feedback control quantity having a value proportional to the integral value of the deviation; A differential controller (75) is configured to calculate a third feedback control quantity by performing a differential operation on the deviation, the third feedback control quantity having a value proportional to the differential value of the deviation; A first adder (76) is configured to calculate a first sum value by adding the feedforward control quantity and the second feedback control quantity; The second adder (77) is configured to calculate the second sum value by adding the first feedback control quantity and the third feedback control quantity; A first limiting processor (79A) is configured to limit the first summed value to a specified allowable range; A second limiting processor (79B) is configured to limit the second summed value within a specified allowable range; and A third adder (78) is configured to calculate the final second control value by adding the first sum value that has passed through the first limit processor (79A) and the second sum value that has passed through the second limit processor (79B).

3. The steering control device (50) according to claim 1, characterized in that, The second calculator (63) includes: A feedforward controller (72) is configured to calculate a feedforward control quantity by performing feedforward control to adapt the actual angle to the target angle; A proportional controller (73) is configured to calculate a first feedback control quantity by performing a proportional operation on the deviation between the actual angle and the target angle, the first feedback control quantity having a value proportional to the deviation; An integral controller (74) is configured to calculate a second feedback control quantity by performing an integral operation on the deviation, the second feedback control quantity having a value proportional to the integral value of the deviation; A differential controller (75) is configured to calculate a third feedback control quantity by performing a differential operation on the deviation, the third feedback control quantity having a value proportional to the differential value of the deviation; The first adder (76) is configured to calculate the final feedback control quantity by adding the first feedback control quantity, the second feedback control quantity and the third feedback control quantity; A first limiting processor (79A) is configured to limit the feedforward control amount to a specified allowable range; A second limiting processor (79B) is configured to limit the final feedback control quantity within a specified allowable range; and The second adder is configured to calculate the final second control quantity by adding the feedforward control quantity that has passed through the first limit processor (79A) and the final feedback control quantity that has passed through the second limit processor (79B).

4. The steering control device (50) according to claim 1, characterized in that, The third calculator (62) is configured to maintain the third control quantity at the value at the point in time when the absolute value of the second control quantity reaches the limit of the specified allowable range, when the absolute value of the second control quantity reaches the limit of the specified allowable range.

5. The steering control device (50) according to claim 1, characterized in that, The steering control device (50) is configured to adjust the second control quantity and the third control quantity such that when the steering wheel is turned while the main control device intervenes in the steering control, the total value of the second control quantity and the third control quantity becomes equal to the second control quantity immediately preceding the turning of the steering wheel.

6. The steering control device (50) according to claim 1, characterized in that, The second calculator (63) is configured to set the values ​​of the proportional gain, integral gain and derivative gain, which are control parameters, to values ​​less than the default values ​​when the steering wheel is turned while the host control device intervenes in the steering control.

7. The steering control device (50) according to claim 1, characterized in that, Also includes: A rotation direction determiner (91) determines whether the rotation state of the steering wheel is a reverse rotation state or a forward rotation state based on the rotation direction of the steering wheel; as well as The correction processing unit (92) corrects the third control quantity calculated by the third calculator (62) to a value less than the original third control quantity corresponding to the rotation state when the rotation direction determiner (91) determines that the rotation state of the steering wheel is the reverse rotation state.

8. The steering control device (50) according to claim 1, characterized in that, Also includes: The fourth calculator (64) limits the value of the second control quantity calculated by the second calculator (63) to a specified allowable range; A rotation direction determiner (91) determines whether the rotation state of the steering wheel is a reverse rotation state or a forward rotation state based on the rotation direction of the steering wheel; as well as The correction processing unit (92) corrects the third control quantity calculated by the third calculator (62) to a value less than the original third control quantity corresponding to the rotation state when the rotation direction determiner (91) determines that the rotation state of the steering wheel is the reverse rotation state.

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