Steering control device

Abstract

The steering control device includes an electric motor for steering angle control; a manual steering operation angle command value calculation section that calculates a manual steering operation angle command value based on a motion equation that includes a steering operation torque and a reaction force control gain; a comprehensive angle command value calculation section that calculates a comprehensive angle command value by adding an automatic steering control angle command value for driving assistance to the manual steering operation angle command value; a control section that controls the electric motor based on the comprehensive angle command value; and a reaction force control gain setting section that sets the reaction force control gain using the steering operation torque, vehicle information, and road information.

Description

TECHNICAL FIELD

[0001] The present application relates to a steering control device. BACKGROUND

[0002] A motor control device disclosed in Patent Document 1 includes a manual steering control command value operation section that operates a manual steering control command value using a steering control torque, a comprehensive angle command value operation section that operates a comprehensive angle command value by adding an automatic steering control command value to the manual steering control command value, and a control section that performs angle control of an electric motor based on the comprehensive angle command value.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-194059

[0004] In the motor control device described in Patent Document 1, in a drive assist mode, steering control that sufficiently reflects the intention of the driver cannot be performed. SUMMARY

[0005] An object of the present application is to provide a steering control device that can perform steering control that sufficiently reflects the intention of the driver in a drive assist mode.

[0006] One embodiment of the present application provides a steering control device including an electric motor for steering angle control, a manual steering control angle command value operation section that operates a manual steering control angle command value based on a motion equation including a steering control torque and a reaction force control gain, a comprehensive angle command value operation section that operates a comprehensive angle command value by adding an automatic steering control angle command value for drive assist to the manual steering control angle command value, a control section that performs angle control of the electric motor based on the comprehensive angle command value, and a reaction force control gain setting section that sets the reaction force control gain using the steering control torque, vehicle information, and road information.

[0007] In this configuration, in a drive assist mode, steering control that sufficiently reflects the intention of the driver can be performed.

[0008] The above and other objects, features and effects of the present application will become clearer from the following description of the embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a schematic view showing the outline configuration of an electric power steering system of a steering control device to which one embodiment of the present application is applied.

[0010] Figure 2 is a block diagram for explaining the electrical configuration of an ECU for motor control.

[0011] Figure 3 is a block diagram showing the structure of the angle control section.

[0012] Figure 4 is a schematic diagram showing a structure example of a physical model of the electric power steering system.

[0013] Figure 5 is a block diagram showing the structure of the disturbance torque estimation section.

[0014] Figure 6 is a schematic diagram showing the structure of the torque control section.

[0015] Figure 7 is a block diagram showing the structure of the driver target lateral deviation setting section.

[0016] Figure 8 is a schematic diagram for explaining the operation of the driver target lateral deviation calculation section.

[0017] Figure 9 is a block diagram showing the structure of the upper ECU for changing the target travel path mainly using the driver target lateral deviation Ay md

[0018] Figure 10 is a schematic diagram for explaining the operation of the correction path candidate generation section.

[0019] Figure 11 is a schematic diagram showing an example of the correction path candidate.

[0020] Figure 12 is a schematic diagram for explaining the operation of the target travel path generation section. DETAILED DESCRIPTION

[0021] [Explanation of Embodiments of the Invention]

[0022] One embodiment of the present invention provides a steering manipulation device including: an electric motor for steering angle control; a manual steering manipulation angle command value calculation section that calculates a manual steering manipulation angle command value based on a motion equation including a steering manipulation torque and a reaction force control gain; a comprehensive angle command value calculation section that calculates a comprehensive angle command value by adding an automatic steering manipulation angle command value for driving assist to the manual steering manipulation angle command value; a control section that performs angle control on the electric motor based on the comprehensive angle command value; and a reaction force control gain setting section that sets the reaction force control gain using the steering manipulation torque, vehicle information, and road information.

[0023] ​In this configuration, steering control that sufficiently reflects the driver's intention can be performed in the drive assist mode.

[0024] In one embodiment of the present application, the reaction force control gain setting section includes a driver target steering angle estimation section that estimates a driver target steering angle using the steering manipulation torque, the vehicle information, and the road information, and a reaction force control gain calculation section that calculates the reaction force control gain using the driver target steering angle.

[0025] In one embodiment of the present application, the reaction force control gain setting section includes a driver target steering angle estimation section that estimates a driver target steering angle using the steering manipulation torque, the vehicle information, and the road information, a driver torque control gain estimation section that estimates a driver torque control gain using the driver target steering angle, the steering manipulation torque, and the rotational angle of the electric motor, and a reaction force control gain calculation section that calculates the reaction force control gain using the driver torque control gain.

[0026] In one embodiment of the present application, the vehicle information is a vehicle speed, and the road information is a curvature of a road.

[0027] In one embodiment of the present application, the steering manipulation device further includes a path change section that changes a target travel path used for calculation of the automatic steering angle command value using the steering manipulation torque or the manual steering angle command value and the vehicle information.

[0028] In one embodiment of the present application, the path change section includes a driver target lateral deviation calculation section that calculates a driver target lateral deviation after a prescribed time using the steering manipulation torque or the manual steering angle command value and the vehicle information, a correction travel path generation section that generates a correction travel path using a lateral deviation after a prescribed time between the driver target lateral deviation and a target travel path based on visual information, and a target travel path generation section that generates a final target travel path by correcting the target travel path based on the visual information based on the correction travel path.

[0029] In one embodiment of the present application, the vehicle information is a vehicle speed and a current lateral deviation from the target travel path based on visual information.

[0030] [Detailed Description of Embodiments of the Present Invention]

[0031] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0032] Figure 1 FIG. 1 is a schematic diagram showing an outline structure of an electric power steering system to which a motor control device according to an embodiment of the present application is applied.

[0033] The electric power steering system 1 is provided with a steering handle 2 as a steering manipulation member for steering a vehicle, a steering mechanism 4 that steers a steered wheel 3 in conjunction with the rotation of the steering handle 2, and a steering manipulation assist mechanism 5 for assisting the steering manipulation of a driver. The steering handle 2 and the steering mechanism 4 are mechanically linked via a steering shaft 6 and an intermediate shaft 7.

[0034] The steering shaft 6 includes an input shaft 8 linked to the steering handle 2 and an output shaft 9 linked to the intermediate shaft 7. The input shaft 8 and the output shaft 9 are linked to be relatively rotatable via a torsion bar 10.

[0035] A torque sensor 12 is disposed in the vicinity of the torsion bar 10. The torque sensor 12 detects a torsion bar torque T tb in the steering handle 2 based on the relative rotational displacement amount of the input shaft 8 and the output shaft 9. tb For example, the torque for the steering manipulation in the left direction is detected as a positive value, the torque for the steering manipulation in the right direction is detected as a negative value, and the greater the absolute value, the greater the magnitude of the torsion bar torque T tb . The torsion bar torque T tb is one example of the "steering manipulation torque" of the present application.

[0036] The steering mechanism 4 is constituted by a gear rack mechanism including a pinion shaft 13 and a rack shaft 14 as a steering shaft. The steered wheels 3 are linked to each end portion of the rack shaft 14 via tie rods 15 and knuckle arms (not shown). The pinion shaft 13 is linked to the intermediate shaft 7. The pinion shaft 13 rotates in conjunction with the steering manipulation of the steering handle 2. A pinion 16 is linked to the front end of the pinion shaft 13.

[0037] The rack shaft 14 extends linearly in the left-right direction of the vehicle. A rack 17 that engages with the pinion 16 is formed in the intermediate portion in the axial direction of the rack shaft 14. The rotation of the pinion shaft 13 is converted to the axial movement of the rack shaft 14 by the pinion 16 and the rack 17. The steered wheels 3 are steered by moving the rack shaft 14 in the axial direction.

[0038] If the steering handle 2 is steered (rotated), the rotation is transmitted to the pinion shaft 13 via the steering shaft 6 and the intermediate shaft 7. Furthermore, the rotation of the pinion shaft 13 is converted to the axial movement of the rack shaft 14 by the pinion 16 and the rack 17. Thus, the steered wheels 3 are steered.

[0039] The steering assist mechanism 5 includes an electric motor 18 for generating a steering assist force (assist torque) and a speed reducer 19 for amplifying the output torque of the electric motor 18 and transmitting to the steering mechanism 4. The speed reducer 19 is constituted by a worm mechanism including a worm 20 and a worm wheel 21 engaged with the worm 20. The speed reducer 19 is housed in a gear housing 22 as a transmission mechanism housing.

[0040] Hereinafter, there is a case where a speed reduction ratio (gear ratio) of the speed reducer 19 is indicated by N. The speed reduction ratio N is defined as a ratio (θ wg / θ ww ) of a rotation angle of the worm 20, i.e., a worm angle θ wg / a rotation angle of the worm wheel 21, i.e., a worm wheel angle θ ww .

[0041] The worm 20 is rotationally driven by the electric motor 18. In addition, the worm wheel 21 is coupled to the output shaft 9 so as to be integrally rotatable.

[0042] If the worm 20 is rotationally driven by the electric motor 18, the worm wheel 21 is rotationally driven, a motor torque is applied to the steering shaft 6, and the steering shaft 6 (output shaft 9) is rotated. Also, the rotation of the steering shaft 6 is transmitted to the pinion shaft 13 via the intermediate shaft 7. The rotation of the pinion shaft 13 is converted into the axial movement of the rack shaft 14. Thus, the steered wheels 3 are steered. That is, by rotationally driving the worm 20 by the electric motor 18, the steering assist based on the electric motor 18 and the steering of the steered wheels 3 can be performed. The electric motor 18 is provided with a rotation angle sensor 23 for detecting the rotation angle of the rotor of the electric motor 18.

[0043] As the torque applied to the output shaft 9 (one example of a drive object of the electric motor 18), there are a motor torque based on the electric motor 18 and a disturbance torque T lc other than the motor torque. lc The disturbance torque T tb other than the motor torque includes a torsion bar torque T rl , a road load torque (road reaction force torque) T f , a friction torque T tb , and the like.

[0044] The torsion bar torque T tb is a torque applied to the output shaft 9 from the steering wheel 2 side through a force applied to the steering wheel 2 by the driver, a force generated by steering inertia, or the like.

[0045] The road load torque T rl is a torque applied to the output shaft 9 from the steered wheels 3 side via the rack shaft 14 through a self-aligning torque generated at the tires, a force generated by the suspension, tire alignment, a friction force of the rack and pinion mechanism, or the like.

[0046] The vehicle is equipped with a CCD (Charge Coupled Device) camera 25 that captures a road ahead in a traveling direction of the vehicle, a GPS (Global Positioning System) 26 that detects a position of the vehicle, a radar 27 that detects a shape of a road, an obstacle, a map information storage 28 that stores map information, a vehicle speed sensor 29 that detects a vehicle speed v x , and the like.

[0047] The CCD camera 25, the GPS 26, the radar 27, the map information storage 28, and the vehicle speed sensor 29 are connected to a host ECU (ECU: Electronic Control Unit) 201 that performs a driving assist control. The host ECU 201 performs a surrounding environment recognition, a position estimation of the vehicle, a path planning, and the like, based on information obtained by the CCD camera 25, the GPS 26, the radar 27, and the vehicle speed sensor 29, map information, and the like, and determines a control target value of a steering operation, a drive actuator.

[0048] In this embodiment, as driving modes, there are a normal mode and a driving assist mode. In this embodiment, the host ECU 201 generates an automatic steering operation angle command value θ md for the driving assist mode, based on a driver target lateral deviation Δy a given from the motor control ECU 202, in addition to information obtained by the CCD camera 25, the GPS 26, the radar 27, and the vehicle speed sensor 29, and map information, in the driving assist mode. a In this embodiment, the driving assist is a lane centering assist (LCA) for causing the vehicle to automatically follow a lane center (lane center line). The automatic steering operation angle command value θ x is a target value of a steering operation angle (a rotation angle of the pinion shaft 13 in this embodiment) for causing the vehicle to travel along the lane center.

[0049] In addition, the host ECU 201 generates a vehicle speed v md , a lateral deviation Δy mode between a target travel path based on visual information and a curvature radius ρ of a road after a prescribed time elapses, and a weight coefficient κ used in a reaction force control gain operation section 55 (refer to Figure 2 ) described later, in the driving assist mode. The target travel path based on visual information is a target travel path generated so as to cause the vehicle to travel along the lane center, mainly based on visual information obtained by the CCD camera 25. In addition, the host ECU 201 generates a mode signal S modeAutomatic steering angle command value θ a Vehicle speed v x , radius of curvature ρ, lateral deviation Δy md The weighting coefficient κ is given to the motor control ECU 202 via the vehicle network.

[0050] Torque T detected by torque sensor 12 tb The output signal of the rotation angle sensor 23 is input to the motor control ECU 202. Based on these input signals and information from the host ECU 201, the motor control ECU 202 controls the electric motor 18.

[0051] Figure 2 This is a block diagram showing the electrical structure of the ECU202 for motor control.

[0052] The following mainly explains the actions when the driving mode is in driving assistance mode.

[0053] The motor control ECU 202 includes: a microcomputer 50; a drive circuit (inverter circuit) 41, controlled by the microcomputer 50, which supplies power to the electric motor 18; and a current detection circuit 42 for detecting the current flowing through the electric motor 18 (hereinafter referred to as "motor current I"). m ”).

[0054] The microcomputer 50 is equipped with a CPU and memory (ROM, RAM, non-volatile memory, etc.), and functions as multiple processing units by executing a prescribed program. These multiple processing units include: a rotation angle calculation unit 51, a reduction ratio division unit 52, a driver target steering angle estimation unit 53, a driver torque control gain estimation unit 54, a reaction force control gain calculation unit 55, a reaction force setting unit 56, a manual steering angle command value calculation unit 57, a comprehensive angle command value calculation unit 58, an angle control unit 59, a torque control unit 60, and a driver target lateral deviation setting unit 61.

[0055] In this embodiment, the "reaction force control gain setting unit" of the present invention is constituted by the driver target steering angle inference unit 53, the driver torque control gain inference unit 54, and the reaction force control gain calculation unit 55.

[0056] The rotation angle calculation unit 51 calculates the rotation angle (rotor rotation angle) θ of the rotor of the electric motor 18 based on the output of the rotation angle sensor 23. m The reduction ratio division unit 52 uses the rotor rotation angle θ calculated by the rotation angle calculation unit 51. m Divide by the reduction ratio N to calculate the rotor rotation angle θ. m The rotation angle converted to the pinion shaft 13 is the pinion angle (steering angle) θ.p .

[0057] The driver target steering angle θ tb is inferred on the basis of the torsion bar torque T x , the vehicle speed v d , and the radius of curvature ρ given from the higher-level ECU 201. The inferred value of θ d is denoted by θ d .

[0058] The driver target steering angle θ d is calculated on the basis of the following equation (1).

[0059] [Mathematical Expression 1]

[0060] Mathematical Expression 1

[0061]

[0062]

[0063]

[0064] In equation (1), the meanings of the respective symbols are as described below.

[0065] θ env : Steering angle required to follow the target travel path according to the road shape (curvature = 1 / ρ)

[0066] θ int : Steering angle corresponding to the driver input

[0067] R s : Over roll gear ratio (ratio of the rotation angle of the steering wheel 2 to the steering angle of the steering wheel 3)

[0068] M: Vehicle weight

[0069] l f : Vehicle fore-aft direction distance from the vehicle center of gravity to the axle of the front wheel

[0070] l r : Vehicle fore-aft direction distance from the vehicle center of gravity to the axle of the rear wheel

[0071] C f : Front wheel cornering power

[0072] C r : Rear wheel cornering power

[0073] J sw : Inertia of the steering wheel 2

[0074] t: current time

[0075] At: prescribed time

[0076] The driver torque control gain estimation section 54 estimates the driver torque control gains k d , c p and torsion bar torque T tb based on the driver target steering angle θ d , the steering wheel angle θ d .

[0077] In this embodiment, if the torque input by the driver to the steering wheel 2 is assumed to be the driver torque T d , then the driver torque T d is assumed to be represented by the following equation (2).

[0078] [Mathematical Equation 2]

[0079] Mathematical Equation 2

[0080]

[0081] In equation (2), θ d is the driver target steering angle, θ sw is the steering wheel angle. k d is a spring constant for specifying the driver torque, c d is a viscous damping coefficient for specifying the driver torque. k d and c d are control gains for specifying the driver torque. That is, in this embodiment, it is assumed that the driver target steering angle θ d is followed by the driver torque control gains k d , c d .

[0082] The driver torque control gain estimation section 54 estimates the driver torque control gains k d , c d using the Kalman filter state equation of the following equation (3) and the Kalman filter observation equation of the following equation (4). The estimated values of k d and c d are denoted by k d and c d .

[0083] [Mathematical Equation 3]

[0084] Mathematical Equation 3

[0085]

[0086]

[0087]

[0088]

[0089]

[0090] [Math. 4]

[0091] [Math. 4]

[0092]

[0093]

[0094] In the formula (3), K is a Kalman filter gain, K tb is a stiffness of the torsion bar 10.

[0095] The reaction force control gain operating section 55 operates the reaction force control gain k d , c d for defining the reaction force to the steering operation of the driver based on the driver torque control gain k a , c a , and a weight coefficient K given from the upper ECU 201. a is a spring constant for defining the reaction force to the steering operation of the driver, and c a is a viscous damping coefficient for defining the reaction force to the steering operation of the driver.

[0096] The reaction force control gain operating section 55 operates the reaction force control gain k a , c a based on the following formula (5).

[0097] [Math. 5]

[0098] [Math. 5]

[0099]

[0100]

[0101] In the formula (5), k a，st is a reference value of the spring constant k a set in advance. c a，st is a reference value of the viscous damping coefficient c a set in advance.

[0102] The weight coefficient K is set based on the situation around, and the like. The weight coefficient K is set to 1, 0, or -1, for example.

[0103] In the case of κ = 1, if the driver torque control gain k d , c d increases, the reaction force control gain k a , c a decreases. At this time, the driver is likely to perform steering operation. The upper ECU 201 sets κ to 1, for example, in a situation in which the risk is low even if the driver performs steering operation. In such a case, the upper ECU 201 is not limited to setting κ to 1, but can set κ to a value of 1 or more.

[0104] In the case of κ = 0, the reaction force control gain k d , c d is a constant value regardless of the value of the driver torque control gain k a , c a .

[0105] In the case of κ = -1, if the driver torque control gain k d , c d increases, the reaction force control gain k a , c a also increases. At this time, it becomes control in which the driving assistance is prioritized over the intervention of the steering operation of the driver. The upper ECU 201 sets κ to -1, for example, in a situation in which the risk is high if the driver performs steering operation. In such a case, the upper ECU 201 is not limited to setting κ to -1, but can set κ to a value of -1 or less.

[0106] The reaction force setting portion 56 sets the steering operation reaction force T a for the driver on the basis of the reaction force control gain k a , c p , the pinion angle θ a , and the automatic steering operation angle command value θ a given from the upper ECU 201. Specifically, the reaction force setting portion 56 sets the steering operation reaction force T a on the basis of the following formula (6).

[0107] [Formula 6]

[0108] Formula 6

[0109]

[0110] The steering operation reaction force T a is 0 in the case where the pinion angle θ p is equal to the automatic steering operation angle command value θ a . If the pinion angle θ p is different from the automatic steering operation angle command value θa The larger the absolute value of the difference, the greater the steering reaction force T. a The larger the absolute value, the greater.

[0111] The manual steering angle command value calculation unit 57 is for setting the steering angle (in this embodiment, the rotation angle of the pinion shaft 13) corresponding to the steering wheel operation (when the driver operates the steering wheel 2) as the manual steering angle command value θ. mdac And that's what it's set up.

[0112] The manual steering angle command value calculation unit 57 is based on the steering reaction force T. a Torque T of the torsion bar tb The column inertia J in the single inertia model (baseline EPS model) including the lower column. c To calculate the manual steering angle command value θ md Specifically, the manual steering angle command value calculation unit 57 calculates the manual steering angle command value θ by solving the differential equation of equation (7). md .

[0113] [Mathematical Expression 7]

[0114] Mathematical Formula 7

[0115]

[0116] The integrated angle command value calculation unit 58 calculates the automatic steering control angle command value θ. a Add the manual steering angle command value θ md To calculate the comprehensive angle command value θ s .

[0117] Angle control unit 59 based on comprehensive angle command value θ s To calculate and synthesize the angle command value θ s The corresponding comprehensive motor torque command value T ms Details regarding the angle control unit 59 will be explained later.

[0118] The torque control unit 60 drives the drive circuit 41 so that the motor torque of the electric motor 18 is close to the motor torque command value T. ms .

[0119] The driver target lateral deviation setting unit 61 will be explained later.

[0120] Figure 3 This is a block diagram showing the structure of the angle control unit 59.

[0121] Angle control unit 59 based on comprehensive angle command value θ sTo calculate the comprehensive motor torque command value T ms The angle control unit 59 includes a low-pass filter (LPF) 71, a feedback control unit 72, a feedforward control unit 73, an interference torque inference unit 74, a torque addition unit 75, an interference torque compensation unit 76, a reduction ratio division unit 77, and a reduction ratio multiplication unit 78.

[0122] The reduction ratio multiplication unit 78 uses the motor torque command value T calculated by the reduction ratio division unit 77 to... ms Multiply by the reduction ratio N of reducer 19 to obtain the motor torque command value T. ms Converted to the pinion shaft torque command value N·T acting on pinion shaft 13 ms .

[0123] Low-pass filter 71 is for the combined angle command value θ s Low-pass filtering is performed. The resulting composite angle command value θ is obtained after low-pass filtering. sl It is given to the feedback control unit 72 and the feedforward control unit 73.

[0124] Feedback control unit 72 is to make the pinion angle θ p The combined angle command value θ after close low-pass filtering sl The feedback control unit 72 includes an angle deviation calculation unit 72A and a PD control unit 72B. The angle deviation calculation unit 72A calculates the comprehensive angle command value θ. sl With pinion angle θ p The deviation Δθ (=θ) sl -θ p Furthermore, the angle deviation calculation unit 72A can also calculate the comprehensive angle command value θ. sl The steering angle inference value ^θ calculated by the disturbance torque inference unit 74 p deviation (θ) sl -^θ p The operation is calculated as the angle deviation Δθ.

[0125] The PD control unit 72B calculates the feedback control torque T by performing PD calculation (proportional-derivative calculation) on the angle deviation Δθ calculated by the angle deviation calculation unit 72A. fb Feedback control torque T fb It is applied to the torque addition section 75.

[0126] The feedforward control unit 73 is provided to compensate for the response delay caused by the inertia of the electric power steering system 1, thereby improving the control responsiveness. The feedforward control unit 73 includes an angular acceleration calculation unit 73A and an inertia multiplication unit 73B. The angular acceleration calculation unit 73A calculates the comprehensive angle command value θ... sl Perform a second-order differential to calculate the target angular acceleration d. 2 θsl / dt 2 .

[0127] The inertial multiplication unit 73B multiplies the target angular acceleration d calculated by the angular acceleration calculation unit 73A. 2 θ sl / dt 2 Multiply by the inertia J of the electric power steering system 1 to calculate the feedforward control torque T. ff (=J·d 2 θ sl / dt 2 Inertia J, for example, is based on the physical model of the electric power steering system 1 described later (see reference). Figure 4 Calculate the feedforward control torque T. ff As an inertia compensation value, it is given to the torque addition unit 75.

[0128] The torque adder 75 controls the feedback torque T fb Add feedforward control torque T ff To calculate the basic torque command value (T) fb +T ff ).

[0129] The disturbance torque estimation unit 74 is provided to estimate the nonlinear torque (disturbance torque: torque other than motor torque) generated as disturbance in the device (the controlled object of the electric motor 18). The disturbance torque estimation unit 74 is based on the pinion shaft torque command value N·T. ms pinion angle θ p To infer the disturbance torque (disturbing load) T lc pinion angle θ p And the differential value of the pinion angle (angular velocity) dθ p / dt. Use ^T respectively. lc ,^θ p and d^θ p / dt represents the disturbance torque T lc pinion angle θ p and the differential value of the pinion angle dθ p The inferred value of / dt. Details regarding the disturbance torque inference unit 74 will be explained later.

[0130] The disturbance torque estimation value ^T calculated by the disturbance torque estimation unit 74 lc The disturbance torque compensation value is given to the disturbance torque compensation unit 76.

[0131] The disturbance torque compensation unit 76 obtains the basic torque command value (T) from the basic torque command value (T). fb +T ff Subtract the disturbance torque estimate ^T lc To calculate the comprehensive steering torque command value Tps (=T fb +T ff -^T lc Therefore, the comprehensive steering torque command value T after compensating for the disturbance torque is obtained. ps (Torque command value for pinion shaft 13).

[0132] Comprehensive steering torque command value T ps The reduction ratio is given to the reduction ratio divider 77. The reduction ratio divider 77 uses the comprehensive steering torque command value T. ps Divide by the reduction ratio N to calculate the overall motor torque command value T. ms The comprehensive motor torque command value T ms The torque is supplied to the torque control unit 60 (see reference). Figure 2 ).

[0133] The disturbance torque estimation unit 74 is described in detail. The disturbance torque estimation unit 74 is, for example, derived from a device using... Figure 4 The physical model 101 of the electric power steering system 1 shown is used to infer the disturbance torque T. lc pinion angle θ p and the angular velocity dθ of the pinion p The interference observer is composed of / dt.

[0134] The physical model 101 includes a device (an example of a motor-driven object) 102, which includes an output shaft 9 and a worm gear 21 fixed to the output shaft 9. A torsion torque T is supplied to the device 102 from the steering wheel 2 via a torsion bar 10. tb And the road load torque T is supplied from the steering wheel 3 side. rl .

[0135] Furthermore, the pinion shaft torque command value N·T is given to device 102 via worm gear 20. ms And the frictional torque T is provided through the friction between the worm gear 21 and the worm 20. f .

[0136] If the inertia of device 102 is set as J, then the equation of motion for the inertia of physical model 101 is expressed by the following equation (8).

[0137] [Mathematical Expression 8]

[0138] Mathematical formula 8

[0139]

[0140] T lc =T tb +T rl +T f

[0141] d 2 θ p / dt 2 is an angular acceleration of the device 102. N is a reduction ratio of the reduction gear 19. T lc represents an interference torque other than the motor torque given to the device 102. In this embodiment, the interference torque T lc is expressed as a sum of a torsion bar torque T tb and a road load torque T rl and a friction torque T f . However, in fact, the interference torque T lc includes a torque other than them.

[0142] The state equation of the physical model 101 with respect to the device 102 is represented by the following equation (9). Figure 4 [Equation 9]

[0143] [Equation 9]

[0144] [Equation 9] [Equation 9]

[0145] [Equation 9] [Equation 9] [Equation 9]

[0146] In the equation (9), x is a state variable vector, u1 is a known input vector, u2 is an unknown input vector, and y is an output vector (a measured value). In addition, in the equation (9), A is a system matrix, B1 is a first input matrix, B2 is a second input matrix, C is an output matrix, and D is a direct matrix.

[0147] The above state equation is extended to a system including the unknown input vector u2 as one of the states. The state equation of the extended system (extended state equation) is represented by the following equation (10).

[0148] [Equation 10]

[0149] [Equation 10] [Equation 10]

[0150] [Equation 10] [Equation 10] [Equation 10]

[0151] In the above equation (10), x e is an extended system state variable vector, and is represented by the following equation (11).

[0152] [Equation 11]

[0153] [Equation 11] [Equation 11]

[0154] [Equation 11] [Equation 11] [Equation 11]

[0155] In the above equation (10), A e is an extended system matrix, B e is a known input matrix of the extended system, and Ce is an output matrix of the extended system.

[0156] According to the extended state equation of the above-described formula (10), a disturbance observer (extended state observer) represented by an equation of the following formula (12) is constructed.

[0157] [Math. 12]

[0158] Math. 12

[0159]

[0160] In formula (12), ^x e represents an estimated value of x e . In addition, L is an observer gain. In addition, ^y represents an estimated value of y. ^x e is represented by the following formula (13).

[0161] [Math. 13]

[0162] Math. 13

[0163]

[0164] In formula (13), ^θ p is an estimated value of θ p , and ^T lc is an estimated value of T lc .

[0165] The disturbance torque estimation section 74 operates the state variable vector ^x e based on the equation of the above-described formula (12).

[0166] Figure 5 is a block diagram representing the structure of the disturbance torque estimation section 74.

[0167] The disturbance torque estimation section 74 includes an input vector input section 81, an output matrix multiplication section 82, a first addition section 83, a gain multiplication section 84, an input matrix multiplication section 85, a system matrix multiplication section 86, a second addition section 87, an integration section 88, and a state variable vector output section 89.

[0168] The pinion shaft torque command value N·T ms operated by the reduction ratio multiplication section 78 (refer to Figure 3 ) is given to the input vector input section 81. The input vector input section 81 outputs an input vector u1.

[0169] The output of the integration section 88 is the state variable vector ^x e (refer to the above-described formula (13)). At the start of operation, an initial value is given as the state variable vector ^x e . The initial value of the state variable vector ^x e is, for example, 0.

[0170] The system matrix multiplication unit 86 makes the state variable vector ^x e Multiply by system matrix A e The output matrix multiplication unit 82 makes the state variable vector ^x e Multiply by the output matrix C e .

[0171] The first addition section 83 is derived from the reduction ratio division section 52 (see reference). Figure 2 The pinion angle θ calculated p That is, the output vector (measured value) y minus the output of the output matrix multiplication unit 82 (C) e ·^x e That is, the first addition unit 83 operates on the output vector y and the output vector inferred value ^y (=C e ·^x e The difference (y-^y) is calculated by the gain multiplier 84, which multiplies the output (y-^y) of the first adder 83 by the observer gain L (refer to equation (12) above).

[0172] The input matrix multiplication unit 85 multiplies the input vector u1 output from the input vector input unit 81 by the input matrix B. e The second addition unit 87 inputs the output (Be·u1) of the input matrix multiplication unit 85 and the output (A) of the system matrix multiplication unit 86. e ·^x e The differential value d^x of the state variable vector is calculated by adding the outputs (L(y-^y)) of the gain multiplier 84. e / dt. The integral part 88 outputs (d^x) to the second addition part 87. e Integrating / dt) to compute the state variable vector ^x e The state variable vector output unit 89 is based on the state variable vector ^x. e To calculate the inferred value of disturbance torque ^T lc Inferred value of pinion angle ^θ p And the inferred value of the pinion angular velocity d^θ p / dt.

[0173] A typical interference observer differs from the extended state observer described above, consisting of the device's inverse model and a low-pass filter. The device's equation of motion is expressed by equation (8) as described above. Therefore, the device's inverse model is equation (14).

[0174] [Mathematical Expression 14]

[0175] Mathematical formula 14

[0176]

[0177] The input to the general disturbance observer is J · d 2 θ p / dt 2 and N · T ms Since the second-order differential value of the pinion angle θ p is used, it is greatly affected by the noise of the rotation angle sensor 23. In contrast, in the extended state observer of the above-described embodiment, the disturbance torque is inferred by the integral type, and thus it is possible to reduce the noise influence caused by the differentiation.

[0178] Further, as the disturbance torque inference section 74, a general disturbance observer configured of an inverse model of the device and a low-pass filter can also be used.

[0179] Figure 6 is a schematic view showing the configuration of the torque control section 60.

[0180] The torque control section 60 (see Figure 2 ) includes a motor current command value operation section 91, a current deviation operation section 92, a PI control section 93, and a PWM (Pulse Width Modulation) control section 94.

[0181] The motor current command value operation section 91 operates a motor current command value I ms by dividing a motor torque command value T t operated by the angle control section 59 (see Figure 2 ) by a torque constant K ms of the electric motor 18.

[0182] The current deviation operation section 92 operates a deviation ΔI (= I ms -I m ) of the motor current command value I ms obtained by the motor current command value operation section 91 from a motor current I m detected by the current detection circuit 42.

[0183] The PI control section 93 generates a drive command value for guiding the motor current I m flowing through the electric motor 18 to the motor current command value I cmd by performing PI operation (proportional integral operation) with respect to the current deviation ΔI operated by the current deviation operation section 92. The PWM control section 94 generates a PWM control signal of a duty ratio corresponding to the above-described drive command value, and supplies it to the drive circuit 41. Thereby, power corresponding to the drive command value is supplied to the electric motor 18. Thereby, the electric motor 18 is driven controlled so that the motor torque becomes equal to the motor torque command value T ms .

[0184] The following describes the driver target lateral deviation setting unit 61 (refer to...). Figure 2 The actions of the engine and the method for generating the target driving path based on the upper-level ECU201 are explained.

[0185] Driver target lateral deviation setting unit 61 based on torsion bar torque T tb The vehicle speed v given by the upper ECU201 x and the current lateral deviation Δy between the target driving path and the visual information-based information. ad Set to the point where a specified time t has elapsed since the current time t0. s The lateral distance the driver wants to move, i.e., the lateral deviation of the driver's target Δy. md .

[0186] The current lateral deviation Δy between the target driving path and the visual information-based information ad It is the lateral distance between the target driving path and the current vehicle reference position based on visual information.

[0187] Figure 7 This is a block diagram showing the structure of the driver target lateral deviation setting unit 61.

[0188] Driver target lateral deviation setting unit 61 (reference) Figure 2 It includes a yaw rate calculation unit 111 and a driver target lateral deviation calculation unit 112.

[0189] Yaw rate calculation unit 111 uses a vehicle model and calculates the yaw rate based on the torsion bar torque T. tb And vehicle speed v x To calculate the yaw rate γ generated under the assumption that the driver assistance is not functioning. d、model Furthermore, the yaw rate calculation unit 111 can also use a vehicle model, based on the manual steering angle command value θ. md And vehicle speed v x To calculate the manual steering angle command value θ md The resulting yaw rate γ d、model .

[0190] like Figure 8 As shown, the driver target lateral deviation calculation unit 112 calculates the value at the assumed vehicle speed v. x With yaw rate γ d、model Constant and at t s The lateral distance the vehicle moves in a stable circular motion within seconds is taken as the driver's target lateral deviation Δy. md .exist Figure 8 In the diagram, the s-axis (horizontal axis) represents the target driving path P based on visual information. eThe d-axis (vertical axis) represents the position along the target travel path P. e The position of the direction orthogonal to the horizontal direction.

[0191] The driver target lateral deviation calculation unit 112 calculates the driver target lateral deviation Δy based on the following formula (15). md .

[0192] [Mathematical Expression 15]

[0193] Mathematical formula 15

[0194]

[0195] The driver target lateral deviation Δy is set by the driver target lateral deviation setting unit 61. md It was assigned to the upper ECU201.

[0196] Figure 9 This indicates the lateral deviation Δy used primarily for driver target applications. md A block diagram of the structure of the upper-level ECU201 that changes the target driving path.

[0197] The upper-level ECU 201 includes a path correction candidate generation unit 211, a path correction selection unit 212, a target driving path generation unit 213, and an automatic steering angle command value generation unit 214. Furthermore, although not shown, the upper-level ECU 201 includes a function to calculate the current lateral deviation Δy between the target driving path and visual information. ad The lateral deviation calculation unit.

[0198] In this embodiment, the "corrected driving path generation unit" of the present invention is constituted by the corrected path candidate generation unit 211 and the corrected path selection unit 212. Furthermore, the "path change unit" of the present invention is constituted by the driver target lateral deviation calculation unit 112, the corrected path candidate generation unit 211, the corrected path selection unit 212, and the target driving path generation unit 213.

[0199] The operation of the path correction candidate generation unit 211 will be explained. For example... Figure 10 As shown, it can measure the current lateral position y0, lateral velocity dy0 / dt, and lateral acceleration d of the vehicle. 2 y0 / dt 2 If the completion time t is determined f lateral position y rf Then by completing the time t f The lateral velocity and lateral acceleration at the point are set to 0, so that a fifth-order function represented by the following equation (16) uniquely determines a candidate correction path.

[0200] [Math. 16]

[0201] [Math. 16]

[0202] yr(t) = a0+ a1t+ a2t2+ a3t3+ a4t4+ a5t5 2 + a3t 3 + a4t 4 + a5t 5 ...(16)

[0203] [a0a1a2a3a4a5]' = ArBv

[0204]

[0205] Further, in this embodiment, the "correction path" refers to a path used in order to correct the target travel path based on the visual information. The "correction path candidate" is a candidate of the "correction path". In addition, the current lateral position y0, the lateral velocity dy0 / dt, and the lateral acceleration d t y0 / dt 2 at the time t 2 are found based on the previous value of the function y f (t) representing the correction path selected by the correction path candidate generation section 211. f rf .

[0206] The correction path candidate generation section 211 sets a plurality of completion times t f and the lateral positions y f at the completion times t rf , finds the coefficients a0, a1, a2, a3, a4, and a5 of the 5th degree function with respect to each combination of them.

[0207] [Math. 17]

[0208] [Math. 17]

[0209] y rf (i) = i · W, i e {-N,..., -1, 0, 1,..., N}

[0210] t f (k) = k · At, k e {1,..., M}...(17)

[0211] In the equation (17), W is a length in the lateral direction (i.e., a direction orthogonal to the direction along the target travel path based on the visual information) set in advance, and At is a time set in advance.

[0212] Thus, as Figure 11As shown, multiple corrective path candidates are generated. For example, in equation (17), if i is set to the five categories of -2, -1, 0, 1, 2, and k is set to the five categories of 1, 2, 3, 4, 5, 25 corrective path candidates are generated.

[0213] The correction path selection unit 212 selects the best correction path candidate as the correction path from the multiple correction path candidates generated by the correction path candidate generation unit 211.

[0214] The path correction selection unit 212 first, based on equation (18), selects each of the multiple path correction candidates based on the lateral acceleration d of the vehicle when it follows the path correction candidate. 2 yr / dt 2 The cost J is calculated using the differential value, i.e., the degree of agitation. y (i, k).

[0215] [Mathematical Expression 18]

[0216] Mathematical formula 18

[0217]

[0218] Furthermore, the coefficients a0, a1, a2, a3, a4, and a5 on the right side of equation (18) are used in conjunction with J on the left side. y The coefficients corresponding to (i, k) in (i, k) are a0, a1, a2, a3, a4, and a5, which are obtained according to equation (16). Additionally, as t f , using J on the left y In (i, k), k corresponds to t in equation (17). f (k).

[0219] Next, as shown in equation (19), the correction path selection unit 212 selects each of the multiple correction path candidates based on the cost J corresponding to the urgency. y (i, k), completion time t f (k), lateral position y rf (i) and lateral deviation Δy ad Difference, lateral position y rf (i) and lateral deviation Δy md The difference generates the cost function C. y (i, k).

[0220] [Mathematical Expression 19]

[0221] Mathematical formula 19

[0222] C y (i,k))=kJJ y (i,k)+ktf t f (k)

[0223] +kad(y rf (i)△y ad ) 2 +k md (y rf (i)△y md ) 2 ...(19)

[0224] In equation (19), k j K t k md and k md These are pre-set weights. If the cost J corresponding to the urgency... y If (i, k) is large, the completion time t f (k) earlier, therefore the cost J corresponding to the degree of urgency y (i, k) and completion time t f (k) is a compromise. If the cost J corresponding to the urgency... y A larger value for (i, k) may worsen ride comfort, but if the cost J corresponding to the agility is [not specified], then [the ride comfort may be compromised]. y A smaller (i, k) results in a longer completion time. Additionally, in equation (19), (y...) rf (i)-Δy ad ) is the difference between the target value of the corrected path candidate and the driving assistance, (y) rf (i)-Δy md ) is the difference between the corrected path candidate and the target value for manual driving.

[0225] As a corrective path, the preferred path is one with low dynamism and early completion time, and (y rf (i)-Δy ad ) 2 Small, and (y) rf (i)-Δy md ) 2 Small.

[0226] Therefore, the modified path selection unit 212 selects the cost function C from multiple modified path candidates. y The candidate with the smallest (i, k) correction path is selected as the optimal correction path.

[0227] The target driving path generation unit 213 corrects the target driving path of the visual information based on the correction path selected by the correction path selection unit 212, thereby generating the final target driving path.

[0228] Specifically, such as Figure 12As shown, the target driving path generation unit 213 generates the final target driving path 303 by adding the correction path 302 selected by the correction path selection unit 212 to the target driving path 301 based on visual information. Figure 12 As shown, the target driving path 301 based on visual information is represented in a coordinate system with the vehicle's forward / backward position as the x-axis and the vehicle's left / right position as the y-axis. Figure 12 In the example, another example represents the case where the corrected path candidate corresponding to k=4 and i=1 is selected as the corrected path.

[0229] Automatic steering angle command value generation unit 214 generates an automatic steering angle command value θ for moving the vehicle along the target driving path generated by target driving path generation unit 213. a .

[0230] Furthermore, when the driving mode is normal mode, the auxiliary torque command value setting unit (in the motor control ECU 202) is set... Figure 2 (Not shown in the diagram) Using torsion bar torque T tb The auxiliary torque command value is set. Furthermore, the torque control unit 60 drives the drive circuit 41 solely based on the auxiliary torque command value.

[0231] In the above embodiment, the reaction force control gain k is set based on the driver target steering angle inference unit 53. a c a Therefore, in driver assistance mode, steering control can fully reflect the driver's intentions.

[0232] Furthermore, in the above-described embodiment, the driver target lateral deviation Δy set by the driver target lateral deviation setting unit 61 can be used as a basis. md It corrects the target driving path based on visual information (and can change the target driving path), thus enabling steering control in driver assistance mode that fully reflects the driver's intentions. This allows for the creation of an appropriate interaction state between the driver and the system.

[0233] The embodiments of the present invention have been described above, but the present invention can also be implemented in other ways. For example, in the above embodiment, the driver torque control gain inference unit 54 is based on the driver's target steering angle θ. d pinion angle θ p and torsion bar torque T tb Determine the spring constant k d and viscosity attenuation coefficient c d Both sides, but it is also possible to deduce only the spring constant k. d With viscosity attenuation coefficient c dEither of them. In this case, only the reaction force control gain k a c a The inferred value of the driver torque control gain is reflected in the reaction force control gain corresponding to a driver torque control gain inferred by the driver torque control gain inference unit 54.

[0234] Furthermore, in the above embodiment, the reaction force control gain calculation unit 55 (refer to...) Figure 2 Based on driver torque control gain^k d ,^c d The reaction force control gain k is calculated using the weighting coefficient κ given by the upper-level ECU201. a c a However, the weighting coefficient κ can also be a fixed value preset in the motor control ECU202.

[0235] Furthermore, in the above embodiment, the angle control unit 59 (refer to...) Figure 2 The system includes a feedforward control unit 73, but this unit can be omitted. In this case, the feedback control torque T calculated by the feedback control unit 72... fb The basic target torque.

[0236] Furthermore, the above embodiments illustrate an example of applying the present invention to a column-type EPS, but the present invention can also be applied to EPS other than column-type EPS. Additionally, the present invention can also be applied to steer-by-wire systems.

[0237] The embodiments of the present invention have been described in detail, but these are merely specific examples used to clarify the technical content of the present invention. The present invention should not be limited to these specific examples, and the scope of the present invention is defined only by the claims.

[0238] Explanation of reference numerals in the attached drawings: 1…Electric power steering; 3…Steering wheel; 4…Steering mechanism; 18…Electric motor; 53…Driver target steering angle inference unit; 54…Driver torque control gain inference unit; 55…Reaction force control gain calculation unit; 56…Reaction force setting unit; 57…Manual steering angle command value calculation unit; 58…Comprehensive angle command value calculation unit; 59…Angle control unit; 60…Torque control unit; 61…Driver target lateral deviation setting unit; 111…Yaw rate calculation unit; 112…Driver target lateral deviation calculation unit; 201…Upper-level ECU 201; 202…Motor control ECU; 211…Corrected path candidate generation unit; 212…Corrected path selection unit; 213…Target driving path generation unit; 214…Automatic steering angle command value generation unit.

Claims

1. A steering control device, wherein, include: An electric motor for steering angle control; The manual steering angle command value calculation unit calculates the manual steering angle command value based on the motion equation including steering torque and reaction force control gain. The integrated angle command value calculation unit adds the manual steering angle command value to the automatic steering angle command value used for driving assistance to calculate the integrated angle command value; The control unit performs angle control on the electric motor based on the comprehensive angle command value; as well as The reaction force control gain setting unit uses the steering torque, vehicle information, and road information to set the reaction force control gain.

2. The steering control device according to claim 1, wherein, The reaction force control gain setting unit includes: The driver target steering angle inference unit uses the steering torque, the vehicle information, and the road information to infer the driver target steering angle; and The reaction force control gain calculation unit calculates the reaction force control gain using the driver's target steering angle.

3. The steering control device according to claim 1, wherein, The reaction force control gain setting unit includes: The driver target steering angle inference unit uses the steering torque, the vehicle information, and the road information to infer the driver target steering angle; The driver torque control gain inference unit uses the driver's target steering angle, the steering torque, and the rotation angle of the electric motor to infer the driver torque control gain; and The reaction force control gain calculation unit uses the driver torque control gain to calculate the reaction force control gain.

4. The steering control device according to any one of claims 1 to 3, wherein, The vehicle information is the vehicle speed, and the road information is the road curvature.

5. The steering control device according to any one of claims 1 to 3, wherein, The steering control device further includes a path changing unit, which uses the steering torque or the manual steering angle command value and the vehicle information to change the target driving path used for calculating the automatic steering angle command value.

6. The steering control device according to claim 5, wherein, The path modification unit includes: The driver target lateral deviation calculation unit uses the steering torque or the manual steering angle command value and the vehicle information to calculate the driver target lateral deviation after a specified time. The corrected driving path generation unit uses the driver's target lateral deviation and the lateral deviation after a predetermined time from the target driving path based on visual information to generate a corrected driving path; and The target driving path generation unit generates the final target driving path by correcting the visual information-based target driving path based on the corrected driving path.

7. The steering control device according to claim 6, wherein, The vehicle information is the vehicle speed and the current lateral deviation from the target driving path based on the visual information.

Images