Steering device

Abstract

This steering device includes a steering mechanism that is mechanically separated from a steering member, a reaction force motor that applies a reaction force torque to the steering member, a steering motor that drives the steering mechanism, a reaction force motor control device that controls the reaction force motor, and a steering motor control device that controls the steering motor, wherein: the reaction force motor control device includes a first target manual steering angle calculating unit that calculates a first target manual steering angle on the basis of steering torque input by a driver, and a steering control unit that controls the reaction force motor using the first target manual steering angle; and the steering motor control device includes a second target manual steering angle calculating unit that calculates a second target manual steering angle on the basis of the steering torque input by the driver, and a steering control unit that controls the steering motor using the second target manual steering angle.

Description

Steering gear

[0001] This disclosure relates to a steering system.

[0002] Patent Document 1 below discloses a steering control device comprising a steering-side control unit that performs reaction force control and a steering-side control unit that performs steering control.

[0003] Patent Document 2 below discloses a steering system comprising a higher-level ECU, a reaction force ECU, and a steering ECU.

[0004] In steer-by-wire systems, where the steering member and the steering mechanism are mechanically separated, the steering angle is generally determined by the steering angle and the VGR (variable gear ratio), making it impossible to control the steering angle independently of the steering angle.

[0005] Japanese Patent Publication No. 2022-53436, Japanese Patent Publication No. 2020-132008, International Publication No. 2024 / 218852

[0006] The purpose of this disclosure is to provide a steering device with a novel configuration.

[0007] One embodiment of the present disclosure provides a steering device comprising: a steering mechanism mechanically separated from a steering member for steering the steering wheels of a vehicle; a reaction motor for applying a reaction torque to the steering member; a steering motor for driving the steering mechanism; a reaction motor control device for controlling the reaction motor; and a steering motor control device for controlling the steering motor, wherein the reaction motor control device includes a first target manual steering angle calculation unit for calculating a first target manual steering angle based on steering torque input by a driver, and a steering control unit for controlling the reaction motor using the first target manual steering angle; and the steering motor control device includes a second target manual steering angle calculation unit for calculating a second target manual steering angle based on steering torque input by a driver, and a steering control unit for controlling the steering motor using the second target manual steering angle.

[0008] This configuration provides a steering system with a novel design.

[0009] The above-mentioned or further other purposes, features, and effects of this disclosure will be made apparent by the following description of embodiments with reference to the accompanying drawings.

[0010] Figure 1 is a schematic diagram showing the general configuration of a steering device according to an embodiment of the present disclosure. Figure 2 is a block diagram illustrating the electrical configuration of the reaction force ECU. Figure 3 is a schematic diagram showing an example of a reference EPS model used in the first manual steering angle command value calculation unit. Figure 4 is a block diagram illustrating the electrical configuration of the steering ECU. Figure 5 is a block diagram illustrating the electrical configuration of a modified example of the reaction force ECU. Figure 6 is a block diagram illustrating a modified example of the configuration enclosed by the dashed line X in Figures 2 and 5.

[0011] [Description of Embodiments of the Present Disclosure] One embodiment of the present disclosure provides a steering device comprising: a steering mechanism mechanically separated from a steering member for steering the steering wheels of a vehicle; a reaction force motor for applying a reaction force torque to the steering member; a steering motor for driving the steering mechanism; a reaction force motor control device for controlling the reaction force motor; and a steering motor control device for controlling the steering motor, wherein the reaction force motor control device includes a first target manual steering angle calculation unit for calculating a first target manual steering angle based on steering torque input by a driver, and a steering control unit for controlling the reaction force motor using the first target manual steering angle; and the steering motor control device includes a second target manual steering angle calculation unit for calculating a second target manual steering angle based on steering torque input by a driver, and a steering control unit for controlling the steering motor using the second target manual steering angle.

[0012] This configuration provides a steering system with a novel design.

[0013] In one embodiment of the present disclosure, the steering mechanism includes a rack shaft, the steering device includes a rack shaft force estimation unit that estimates the rack shaft force acting on the rack shaft via the steering wheels, the reaction motor control device includes a target driver torque calculation unit that calculates a target driver torque to be input by the driver to the steering member using the rack shaft force estimated by the rack shaft force estimation unit, and a feedback control torque calculation unit that calculates a feedback control torque by performing torque feedback control so that the steering torque follows the target driver torque, and the first target manual steering angle calculation unit calculates the first target manual steering angle based on the feedback control torque and the steering torque.

[0014] In one embodiment of the present disclosure, the steering device has a function to vary a virtual gear ratio representing the ratio of the steering angle to the steering angle, the reaction motor control device includes a selection unit that selects either a first target steering angle provided by a control device higher than the reaction motor control device and the steering motor control device, and a second target steering angle calculated using the actual steering angle and the gear ratio, or a target integrated steering angle which is the sum of the target steering angle provided by the higher control device and the second target manual steering angle and the gear ratio, and a target integrated steering angle calculation unit that calculates the target integrated steering angle by adding the target steering angle selected by the selection unit to the first target manual steering angle, and the steering control unit is configured to control the reaction motor using the target integrated steering angle.

[0015] In one embodiment of the present disclosure, the steering device has a function to vary a virtual gear ratio representing the ratio of the steering angle to the steering angle, the reaction motor control device includes a selection unit that selects one of the following: a first target steering angle provided by a control device higher than the reaction motor control device and the steering motor control device, a second target steering angle calculated using the actual steering angle and the gear ratio, or a target integrated steering angle which is the sum of the target steering angle and the second target manual steering angle provided by the higher control device and the gear ratio, and the first target manual steering angle, and the steering control unit is configured to control the reaction motor using the one target steering angle selected by the selection unit.

[0016] [Detailed Description of Embodiments of the Disclosure] Embodiments of the Disclosure will be described in detail below with reference to the accompanying drawings.

[0017] Figure 1 is a schematic diagram showing the general configuration of a steering device according to an embodiment of the present disclosure.

[0018] The steering system 1 includes a steering wheel (handle) 2 as a steering member for steering the vehicle, a steering mechanism 4 for steering the steering wheels 3, and a steering shaft 5 connected to the steering wheel 2. However, there is no mechanical connection between the steering shaft 5 and the steering mechanism 4 that transmits torque, rotation, or other motion.

[0019] The steering shaft 5 includes a first shaft 7 with one end connected to the steering wheel 2, a torsion bar 8 with one end connected to the other end of the first shaft 7, and a second shaft 9 with one end connected to the other end of the torsion bar 8.

[0020] A torque sensor 11 is positioned near the torsion bar 8. The torque sensor 11 determines the torsion bar torque (steering torque) T applied to the steering wheel 2 based on the relative rotational displacement of the first shaft 7 and the second shaft 9. ｔｂ The torsion bar torque T detected by the torque sensor 11 is detected. In this embodiment, the torsion bar torque T is detected by the torque sensor 11. ｔｂFor example, the torque for steering to the left is detected as a positive value, and the torque for steering to the right is detected as a negative value, and the larger the absolute value, the greater the torsion bar torque T. ｔｂ Assume that the size of will increase.

[0021] A reaction motor 13 is connected to the second shaft 9 via a reduction gear 12 to control the rotation angle of the second shaft 9 (hereinafter sometimes referred to as the "actual steering angle"). The reaction motor 13 is an electric motor that applies a reaction torque to the second shaft 9.

[0022] The reduction gear 12 consists of a worm gear mechanism including a worm shaft (not shown) that is integrally rotatably connected to the output shaft of the reaction motor 13, and a worm wheel (not shown) that meshes with the worm shaft and is integrally rotatably connected to the second shaft 9. The reaction motor 13 is provided with a rotation angle sensor 14 for detecting the rotation angle of the reaction motor 13.

[0023] The steering mechanism 4 consists of a rack and pinion mechanism including a pinion shaft 15 and a rack shaft 16. Steering wheels 3 are connected to each end of the rack shaft 16 via tie rods 17 and knuckle arms (not shown). The pinion shaft 15 is connected to the output shaft of the steering motor 19 via a reduction gear 18. The reduction gear 18 consists of a worm gear mechanism including a worm shaft (not shown) that is integrally rotatably connected to the output shaft of the steering motor 19, and a worm wheel (not shown) that meshes with this worm shaft and is integrally rotatably connected to the pinion shaft 15. A pinion 15A is connected to the tip of the pinion shaft 15. The steering motor 19 is provided with a rotation angle sensor 20 for detecting the rotation angle of the steering motor 19.

[0024] In the following, the reduction ratio of the speed reducer 12 (hereinafter referred to as the "first reduction ratio") may be represented by N1, and the reduction ratio of the speed reducer 18 (hereinafter referred to as the "second reduction ratio") may be represented by N2. The reduction ratio is the worm wheel angle θ, which is the rotation angle of the worm wheel. ｗｗ The worm gear angle θ is the rotation angle of the worm gear relative to the given value. ｗｇ The ratio θ ｗｇ / θ ｗｗ It is defined as follows.

[0025] The rack shaft 16 extends linearly along the left-right direction of the vehicle. A rack 16A meshing with a pinion 15A is formed on the rack shaft 16. When the steering motor 19 rotates, the rotational force thereof is transmitted to the pinion shaft 15 via the reduction gear 18. Then, the rotation of the pinion shaft 15 is converted into axial movement of the rack shaft 16 by the pinion 15A and the rack 16A. Thereby, the steered wheels 3 are steered.

[0026] The vehicle is equipped with a CCD (Charge Coupled Device) camera 25 for photographing a road ahead of the vehicle in the traveling direction, a GPS (Global Positioning System) 26 for detecting the position of the own vehicle, a radar 27 for detecting road shapes and obstacles, a map information memory 28 storing map information, and a vehicle speed sensor 29 for detecting a vehicle speed V.

[0027] The CCD camera 25, the GPS 26, the radar 27, the map information memory 28, and the vehicle speed sensor 29 are connected to an ADAS domain ECU 201 and a vehicle motion domain ECU 202 for performing driving assistance control and automatic driving control.

[0028] To the ADAS domain ECU 201, an actual steering angle θ is supplied from a reaction force ECU 203 described later ｒｐ via an in-vehicle network. Further, to the ADAS domain ECU 201, an actual turning angle θ is supplied from a steering ECU 204 described later ｓｐ via the in-vehicle network.

[0029] The ADAS domain ECU 201 is configured such that, for example, information obtained from the CCD camera 25, the GPS 26, the radar 27, the map information memory 28, and the vehicle speed sensor 29, the actual steering angle θ ｒｐ , the actual turning angle θ ｓｐBased on these factors, the target curvature K for driver assistance control and autonomous driving control is calculated. The information obtained from the CCD camera 25, GPS 26, radar 27, map information memory 28, and vehicle speed sensor 29 may include the actual curvature. The target curvature K calculated by the ADAS domain ECU 201 is provided to the vehicle motion domain ECU 202 via the in-vehicle network.

[0030] The vehicle motion domain ECU 202 uses information obtained from, for example, the CCD camera 25, GPS 26, radar 27, map information memory 28, and vehicle speed sensor 29, along with the target curvature K, to determine the first target steering angle θ corresponding to the target curvature K. ａｒ１ and target steering angle θ ａｓ The following is calculated. In this embodiment, the first target steering angle θ ａｒ１ This is the target value of the steering angle (target automatic steering angle) for automatically driving the vehicle along the target driving line. In this embodiment, the target steering angle θ ａｓ This is the target value of the steering angle (target automatic steering angle) for automatically driving the vehicle along the target driving line. Note that the first target steering angle θ is... ａｒ１ There may be a mode in which is fixed to 0 [deg].

[0031] Furthermore, the vehicle motion domain ECU 202 controls the selector 43 in the reaction force ECU 203, which will be described later, by selecting the select flag F ｓ Set it.

[0032] First target steering angle θ ａｒ１ Select Flag F ｓ The vehicle speed V is provided from the vehicle motion domain ECU 202 to the reaction force ECU 203 via the in-vehicle network. Target steering angle θ ａｓ The vehicle speed V is provided to the steering ECU 204 from the vehicle motion domain ECU 202 via the in-vehicle network. The reaction force ECU 203 is an ECU for controlling the reaction force motor 13, and the steering ECU 204 is an ECU for controlling the steering motor 19.

[0033] The ADAS domain ECU 201 and the vehicle motion domain ECU 202 are higher-level ECUs than the reaction force ECU 203 and the steering ECU 204, so these domain ECUs 201 and 202 may be collectively referred to as higher-level ECUs. "ADAS domain ECU 201 and vehicle motion domain ECU 202" or "vehicle motion domain ECU 202" is an example of a "higher-level control device" in this disclosure. The reaction force ECU 203 is an example of a "reaction force motor control device" in this disclosure. The steering ECU 204 is an example of a "steering motor control device" in this disclosure.

[0034] In this embodiment, the first target steering angle θ ａｒ１ and the first target manual steering angle θ, which will be described later. ｍｒ This is expressed as the amount of rotation (rotation angle) from the neutral position of the second axis 9, with a positive value representing rotation in the left steering direction from the neutral position, and a negative value representing rotation in the right steering direction from the neutral position. Furthermore, the target steering angle θ is expressed as follows: ａｓ and the second target manual steering angle θ, which will be described later. ｍｓ This is expressed as the amount of rotation (angle of rotation) of the pinion shaft 15 from the neutral position, with a positive value representing the amount of rotation in the left steering direction from the neutral position, and a negative value representing the amount of rotation in the right steering direction from the neutral position.

[0035] Torsion bar torque T detected by torque sensor 11 ｔｂ The output signal from the rotation angle sensor 14 is input to the reaction force ECU 203. The reaction force ECU 203 processes these input signals and the information (θ) provided from the vehicle motion domain ECU 202. ａｒ１ , F ｓ , V) and information (θ) provided from the steering ECU 204 ａｒ２ , F ｒ The reaction motor 13 is controlled based on the following.

[0036] The output signal from the rotation angle sensor 20 is input to the steering ECU 204. The steering ECU 204 receives the output signal from the rotation angle sensor 20 and information (θ) from the vehicle motion domain ECU 202. ａｓ , V) and information (T) provided from the reaction force ECU 203 ｔｂ The steering motor 19 is controlled based on the following.

[0037] Figure 2 is a block diagram illustrating the electrical configuration of the reaction force ECU 203.

[0038] The reaction force ECU 203 includes a microcomputer 40, a drive circuit (inverter circuit) 31 controlled by the microcomputer 40 that supplies power to the reaction force motor 13, and the current (hereinafter referred to as "motor current I") that flows through the reaction force motor 13. ｒｍ It includes a current detection circuit 32 for detecting the following:

[0039] The microcomputer 40 is equipped with a CPU and memory (ROM, RAM, non-volatile memory, etc.) and functions as multiple function processing units by executing a predetermined program. These multiple function processing units include a rotation angle calculation unit 41, a reduction ratio division unit 42, a selector 43, a target driver torque calculation unit 44, a torque deviation calculation unit 45, a PD control unit (torque feedback control unit) 46, a first target manual steering angle calculation unit 47, a target integrated steering angle calculation unit 48, and a first angle control unit 49.

[0040] The rotation angle calculation unit 41 calculates the rotor rotation angle θ of the reaction motor 13 based on the output signal of the rotation angle sensor 14. ｒｍ The reduction ratio division unit 42 calculates the rotor rotation angle θ. ｒｍ By dividing by the first reduction ratio N1, the rotor rotation angle θ ｒｍ The rotation angle (actual steering angle) of the second axis 9 is θ ｒｐ Convert to actual steering angle θ. ｒｐ This is provided to the target drive torque calculation unit 44 and also to the ADAS domain ECU 201.

[0041] The selector 43 receives the first target steering angle θ from the vehicle motion domain ECU 202. ａｒ１ and select flag F ｓ And the second target steering angle θ from the steering ECU 204 ａｒ２ and are given. Select flag F ｓ The first target steering angle θ ａｒ１ and the second target steering angle θ ａｒ２ This is a flag used to specify which of the following to select. Select Flag F ｓThe value is set by the vehicle motion domain ECU 202. The vehicle motion domain ECU 202 selects flag F based on information provided by various sensors. ｓ You may set the value, or select flag F based on driver operation. ｓ You may set a value.

[0042] Selector 43 controls the first target steering angle θ. ａｒ１ and the second target steering angle θ ａｒ２ Select either one of the flags F ｓ Select and output based on the value of [the variable].

[0043] The target driver torque calculation unit 44 calculates the rack axial force F supplied from the steering ECU 204. ｒ Using this, the target driver torque T that the driver should input to the steering wheel 2 (steering shaft 5) is determined. ｄ The calculation is performed. In this embodiment, the target driver torque calculation unit 44 calculates the actual steering angle θ calculated by the reduction ratio division unit 42. ｒｐ Torsion bar torque T detected by torque sensor 11 ｔｂ , the rack axial force F supplied from the steering ECU 204 ｒ The vehicle speed V, provided by the vehicle motion domain ECU 202, is input. Based on these inputs, the target driver torque calculation unit 44 calculates the target driver torque T ｄ Perform the calculation.

[0044] The target driver torque calculation unit 44 may, for example, perform the base target torque calculation process M20, the compensation amount calculation process M21, and the addition process M22 shown in Figure 3 of International Publication No. 2024 / 218852 (Patent Document 3). In this case, the target driver torque calculation unit 44 calculates the rack axial force F ｒ Based on the vehicle speed V, the target basic driver torque T is the basic value of the target driver torque that the driver should input to the steering shaft 5 via the steering wheel 2. ｄｂ The calculation is performed. In addition, the target driver torque calculation unit 44 calculates the actual steering angle θ. ｒｐ Based on the vehicle speed V, the target basic driver torque T ｄｂ Compensation amount T to compensate for ｄｒNext, the target driver torque calculation unit 44 calculates the target basic torque T. ｄｂ Compensation amount T ｄｒ By adding this, the target driver torque T ｄ Perform the calculation.

[0045] The target driver torque calculation unit 44 calculates the target basic driver torque T ｄｂ Target driver torque T ｄ It may also be used as such.

[0046] The torque deviation calculation unit 45 calculates the target reaction torque T ｄ Torsion bar torque T ｔｂ Torque deviation ΔT(=T ｄ -T ｔｂ The PD control unit 46 calculates the feedback control torque T by performing a PD calculation (proportional-derivative calculation) on the torque deviation ΔT. ｄｆｂ Perform the calculation.

[0047] The first target manual steering angle calculation unit 47 basically calculates the steering angle (more precisely, the rotation angle θ of the second axis 9) corresponding to the steering wheel operation when the driver operates the steering wheel 2. ｒｐ ) is the first target manual steering angle θ ｍｒ It is provided for setting it as such.

[0048] In this embodiment, the first target manual steering angle calculation unit 47 uses a reference EPS model to calculate the first target manual steering angle θ ｍｒ Perform the calculation.

[0049] Figure 3 is a schematic diagram showing an example of a reference EPS model used in the first target manual steering angle calculation unit 47.

[0050] This reference EPS model is a single inertia model including a lower column. The lower column corresponds, for example, to the worm wheel of the second shaft 9 and the reduction gear 12. In Figure 3, J ｃ θ is the inertia of the lower column (hereinafter referred to as "column inertia"), and ｃ is the rotation angle of the lower column, and T ｔｂ This is the torsion bar torque. The lower column has the torsion bar torque T ｔｂ, torque N1·T acting on the second shaft 9 from the reaction force motor 13 ｍ and road surface reaction torque T ｒｌ is applied.

[0051] Road surface reaction torque T ｒｌ is expressed by the following equation (1) using the spring constant k of a virtual spring and the viscous damping coefficient c of a virtual damper.

[0052] T ｒｌ =-k·θ ｃ -c(dθ ｃ / dt)...(1)

[0053] The equation of motion of the reference EPS model is expressed by the following equation (2).

[0054] J ｃ ·d ２ θ c / dt ２ =T ｔｂ +N1·T ｍ -k·θ ｃ -c(dθ ｃ / dt)...(2)

[0055] In equation (2), J ｃ ·d ２ θ ｃ / dt ２ is the moment of inertia acting on the lower column.

[0056] The first target manual steering angle calculation unit 47 substitutes the torsion bar torque T ｔｂ detected by the torque sensor 11 into T ｔｂ , substitutes the feedback control torque T ｍ calculated by the PD control unit 46 into N1·T ｄｆｂ , substitutes the preset first spring constant k1 as k and the preset first viscous damping coefficient c1 as c, and solves the differential equation of equation (2) to calculate the rotation angle θ ｃ of the lower column. Then, the first target manual steering angle calculation unit 47 sets the obtained rotation angle θ ｃ of the lower column as the first target manual steering angle θ ｍｒ

[0057] That is, the first target manual steering angle calculation unit 47 calculates N1·T in equation (2)​ｍ , θ ｃ , k and c are T ｄｆｂ , θ ｍｒ By solving the differential equation (3) below, with k1 and c1 substituted, the first target manual steering angle θ can be found. ｍｒ Perform the calculation.

[0058] J ｃ d ２ θ ｍｒ / dt ２ = T ｔｂ +T ｄｆｂ -k1・θ ｍｒ -c1(dθ ｍｒ / dt) ... (3)

[0059] The target integrated steering angle calculation unit 48 calculates the first target manual steering angle θ. ｍｒ The target steering angle θ selected by the selector 43 is then used. ａｒ (θ ａｒ１ or θ ａｒ２ Adding this, the target integrated steering angle θ ｉｒ Perform the calculation.

[0060] The first angle control unit 49 controls the target integrated steering angle θ ｉｒ Based on this, the reaction motor 13 is angle-controlled. Specifically, the first angle control unit 49 controls the actual steering angle θ ｒｐ (The rotation angle of the second axis 9) is the target integrated steering angle θ ｉｒ The drive circuit 31 is controlled to follow this.

[0061] For example, the first angle control unit 49 first determines the target integrated steering angle θ ｉｒ and the actual steering angle θ ｒｐ The angular deviation (θ) ｉｒ -θ ｒｐ The first angle control unit 49 calculates the target second shaft torque, which is the target torque for the second shaft 9, by performing a PD calculation (proportional-derivative calculation) on the first shaft torque. Next, the first angle control unit 49 calculates the target motor torque, which is the target torque for the reaction motor 13, by dividing the target second shaft torque by the first reduction ratio N1. Next, the first angle control unit 49 calculates the target motor current for the reaction motor 13 by dividing the target motor torque by the torque coefficient of the reaction motor 13. Next, the first angle control unit 49 calculates the target motor current and the motor current I detected by the current detection circuit 32.ｒｍ The drive command value is calculated by performing PID calculation (proportional-integral-derivative calculation) on the current deviation. Finally, the first angle control unit 49 generates a PWM signal with a duty cycle corresponding to the drive command value and supplies it to the drive circuit 31.

[0062] The first angle control unit 49 controls the target second axis torque and the actual steering angle θ. ｒｐ Based on this, the system may include a disturbance torque estimation unit that estimates a nonlinear torque (disturbance torque: torque other than motor torque) that occurs as a disturbance in the object driven by the reaction force motor 13. In that case, the first angle control unit 49 may calculate the target second shaft torque with the disturbance torque compensated by subtracting the disturbance torque estimated by the disturbance torque estimation unit from the target second shaft torque, and then calculate the target motor torque by dividing the obtained target second shaft torque after disturbance torque compensation by the first reduction ratio N1.

[0063] Figure 4 is a block diagram illustrating the electrical configuration of the steering ECU 204.

[0064] The steering ECU 204 includes a microcomputer 60, a drive circuit (inverter circuit) 51 controlled by the microcomputer 60 that supplies power to the steering motor 19, and the current (hereinafter referred to as "motor current I") that flows through the steering motor 19. ｓｍ It includes a current detection circuit 52 for detecting the following:

[0065] The microcomputer 60 is equipped with a CPU and memory (ROM, RAM, non-volatile memory, etc.) and functions as multiple function processing units by executing a predetermined program. These multiple function processing units include a rotation angle calculation unit 61, a reduction ratio division unit 62, a second target steering angle calculation unit 63, a rack axis force estimation unit 64, a second target manual steering angle calculation unit 65, a target integrated steering angle calculation unit 66, and a second angle control unit 67.

[0066] The rotation angle calculation unit 61 calculates the rotor rotation angle θ of the steering motor 19 based on the output signal of the rotation angle sensor 20. ｓｍ The reduction ratio division unit 62 calculates the rotor rotation angle θ. ｓｍBy dividing by the second reduction ratio N2, the rotor rotation angle θ is obtained. ｓｍ The rotation angle (actual steering angle) of the pinion shaft 15 is θ ｓｐ Convert to actual steering angle θ. ｓｐ This is provided to the second target steering angle calculation unit 63 and also to the ADAS domain ECU 201.

[0067] The second target steering angle calculation unit 63 calculates the actual steering angle θ ｓｐ By dividing this by a virtual gear ratio (VGR: ratio of steering angle to steering angle) set according to the vehicle speed V, the actual steering angle θ is obtained. ｓｐ The second target steering angle (steering angle equivalent value) θ is determined by the gear ratio VGR. ａｒ２ The second target steering angle θ is calculated. ａｒ２ This force is supplied to the rack axial force estimation unit 64 and also to the reaction force ECU 203.

[0068] The rack axial force estimation unit 64, for example, determines the second target steering angle θ. ａｒ２ Based on the vehicle speed V, the rack axial force F acts on the rack shaft 16 via the steering wheels 3. ｒ Specifically, the rack axial force estimation unit 64 estimates the second target steering angle θ. ａｒ２ The larger the absolute value of F, the greater the rack axial force. ｒ The absolute value of increases, and the greater the vehicle speed V, the greater the rack axial force F. ｒ The rack axial force F is increased so that its absolute value becomes larger. ｒ The rack axial force F is calculated. ｒ This is applied to the reaction force ECU 203.

[0069] The second target manual steering angle calculation unit 65 basically calculates the steering angle (more precisely, the rotation angle θ of the pinion shaft 15) corresponding to the steering wheel operation when the driver operates the steering wheel 2. ｓｐ ) is the second target manual steering angle θ ｍｓ It is provided for setting it as such.

[0070] The operation of the second target manual steering angle calculation unit 65 is almost the same as the operation of the first target manual steering angle calculation unit 47. However, the low column of the reference EPS model in Figure 3 corresponds, for example, to the pinion shaft 15 and the worm wheel of the reduction gear 18. In addition, the low column has a torsion bar torque T detected by the torque sensor 11. ｔｂ Torque N2·T acting from the steering motor 19 to the pinion shaft 15 ｍ and road surface reaction torque T ｒｌ It is given.

[0071] The second target manual steering angle calculation unit 65 calculates the T in equation (2) above. ｔｂ Torsion bar torque T detected by torque sensor 11 ｔｂ Substitute N1・T ｍ By substituting 0 for k, substituting the pre-set second spring constant k2 for k, and substituting the pre-set second viscous damping coefficient c2 for c, and solving the differential equation (2), the rotation angle θ of the lower column can be found. ｃ The second target manual steering angle calculation unit 65 then calculates the rotation angle θ of the lower column obtained. ｃ The second target manual steering angle θ ｍｓ Set it as follows.

[0072] In other words, the second target manual steering angle calculation unit 65 is N1・T in equation (2). ｍ , θ ｃ , k and c are set to 0 and θ respectively. ｍｓ By solving the differential equation (4) below, with k2 and c2 substituted, the second target manual steering angle θ can be found. ｍｓ Perform the calculation.

[0073] J ｃ d ２ θ ｍｓ / dt ２ = T ｔｂ -k²θ ｍｓ -c²(dθ) ｍｓ / dt) ... (4)

[0074] Note that J in equation (4) ｃ For example, the inertia of the pinion shaft 15 and the worm wheel of the reduction gear 18 can be used.

[0075] The target integrated steering angle calculation unit 66 calculates the second target manual steering angle θ. ｍｓ The target steering angle θ is given by the vehicle motion domain ECU 202. ａｓ Adding this, the target integrated steering angle θ ｉｓ Perform the calculation.

[0076] The second angle control unit 67 controls the target integrated steering angle θ ｉｓ Based on this, the steering motor 19 is angle-controlled. Specifically, the second angle control unit 67 controls the actual steering angle θ ｓｐ (The rotation angle of the pinion shaft 15) is the target integrated steering angle θ ｉｓ The drive circuit 51 is controlled to follow this.

[0077] For example, the second angle control unit 67 first determines the target integrated steering angle θ ｉｓ and the actual steering angle θ ｓｐ The angular deviation (θ) ｉｓ -θ ｓｐ Next, the second angle control unit 67 calculates the target pinion shaft torque, which is the target torque for the pinion shaft 15, by performing a PD calculation (proportional-derivative calculation) on the target pinion shaft torque. Next, the second angle control unit 67 calculates the target motor torque, which is the target torque for the steering motor 19, by dividing the target pinion shaft torque by the second reduction ratio N2. Next, the second angle control unit 67 calculates the target motor current for the steering motor 19 by dividing the target motor torque by the torque coefficient of the steering motor 19. Next, the second angle control unit 67 calculates the target motor current and the motor current I detected by the current detection circuit 52. ｓｍ The drive command value is calculated by performing PID calculation (proportional-integral-derivative calculation) on the current deviation. Finally, the second angle control unit 67 generates a PWM signal with a duty cycle corresponding to the drive command value and supplies it to the drive circuit 51.

[0078] The second angle control unit 67 controls the target pinion shaft torque and the actual steering angle θ. ｓｐBased on this, the steering motor 19 may be equipped with a disturbance torque estimation unit that estimates a nonlinear torque (disturbance torque: torque other than motor torque) that occurs as a disturbance in the object it drives. In that case, the second angle control unit 67 may calculate the target pinion shaft torque with the disturbance torque compensated by subtracting the disturbance torque estimated by the disturbance torque estimation unit from the target pinion shaft torque, and then calculate the target motor torque by dividing the obtained target pinion shaft torque after disturbance torque compensation by the second reduction ratio N2.

[0079] In Figure 4, the second target steering angle calculation unit 63 calculates the actual steering angle θ. ｓｐ By dividing by VGR, the second target steering angle θ is obtained. ａｒ２ It is calculating the target integrated steering angle θ, as shown by the dashed line in Figure 4. ｉｓ By dividing by VGR, the second target steering angle θ is obtained. ａｒ２ The calculation may also be performed. In this case, the second target steering angle calculation unit 63 calculates the second target manual steering angle θ. ｍｓ Target steering angle θ ａｓ The target integrated steering angle θ obtained by adding these values ｉｓ The second target steering angle (steering angle equivalent value) θ is defined by the VGR. ａｒ２ Perform the calculation.

[0080] Furthermore, in Figure 4, the rack axial force estimation unit 64 determines the second target steering angle θ. ａｒ２ Based on the vehicle speed V, the rack axial force F ｒ It estimates the target pinion shaft torque (target integrated steering angle θ) calculated by the second angle control unit 67. ｉｓ and the actual steering angle θ ｓｐ The angular deviation (θ) ｉｓ -θ ｓｐ Based on the target pinion shaft torque obtained by performing PD calculation on ), the rack shaft force F ｒ It is also possible to estimate the rack axial force. Furthermore, the rack axial force estimation unit 64 should be one capable of estimating the rack axial force, and may be one capable of estimating the rack axial force using a method different from the one described above.

[0081] In the above-described embodiment, the target integrated steering angle calculation unit 66 in the steering ECU 204 calculates the second target manual steering angle θ ｍｓ The target steering angle (target automatic steering angle) θ ａｓ By adding this, the target integrated steering angle θ ｉｓ The calculation is performed. Then, the steering angle θ is calculated. ｓｐ The target integrated steering angle θ ｉｓ The drive circuit 51 is controlled to follow this.

[0082] The target integrated steering angle calculation unit 48 within the reaction force ECU 203 calculates the first target steering angle (target automatic steering angle) θ ａｒ１ Alternatively, the second target steering angle (converted steering angle value) θ ａｒ２ The target steering angle θ selected by the selector 43 from among these options is selected by the selector 43. ａｒ The first target manual steering angle θ ｍｒ By adding this, the target integrated steering angle θ ｉｒ The steering angle θ is calculated. ｒｐ The target integrated steering angle θ ｉｒ The drive circuit 31 is controlled to follow this.

[0083] The second target steering angle θ is controlled by the selector 43. ａｒ２ If selected, the target integrated steering angle θ ｉｒ The steering angle θ is ｓｐ The second target steering angle θ is obtained by dividing by VGR. ａｒ２ The first target manual steering angle θ ｍｒ The value obtained is the sum of the values. Therefore, in this case, the steering angle θ ｒｐ The steering angle θ ｓｐ It can be related to.

[0084] Meanwhile, the selector 43 controls the first target steering angle θ ａｒ１ If selected (first target steering angle θ) ａｒ１ (Including the case where is set to zero) Target integrated steering angle θ ｉｒ The first target steering angle θ ａｒ１ The first target manual steering angle θ ｍｒ The value obtained is the sum of the values. Therefore, in this case, the steering angle θ ｒｐ The steering angle θ ｓｐIt cannot be related to the steering angle. In other words, in this case, it becomes possible to control the steering angle independently of the steering angle.

[0085] For example, ADAS (Advanced Driver-Assistance System) Level 2 ＋ When driver steering and automated driving by the system coexist, as in this case, the driver must constantly be aware of the system's steering behavior. In such cases, the steering angle θ ｒｐ The steering angle θ ｓｐ It is preferable to keep it related to this. In such cases, the vehicle motion domain ECU 202 selects the F ｓ The flag value is the second target steering angle θ ａｒ２ It is preferable to set this as the flag value for selection.

[0086] On the other hand, in cases where driving is performed solely by the system, such as in ADAS Level 4, the driver does not need to be aware of the steering behavior of the system. In such cases, the steering angle θ ｒｐ The steering angle θ ｓｐ There is no need to relate it to. Therefore, in such cases, the vehicle motion domain ECU 202 selects the F ｓ The flag value is set to the first target steering angle θ. ａｒ１ Set this as the flag value for selecting, and the first target steering angle θ ａｒ１ It is preferable to set it to 0 [deg].

[0087] Furthermore, for example, when driving around a curve in ADAS Level 2, the vehicle motion domain ECU 202 selects the F ｓ The flag value is set to the first target steering angle θ. ａｒ１ Set this as the flag value for selecting, and the first target steering angle θ ａｒ１ It is preferable to set the steering angle to 0 [deg]. The reason for this is as follows: When driving around a curve, it is preferable to set the steering angle to 0 [deg] or a small steering angle that does not require changing the steering position. This is because setting the steering angle in this way eliminates the need to maintain steering while driving around a curve. Therefore, in such cases, the steering angle θ ｒｐ The steering angle θｓｐ It is preferable not to associate it with that.

[0088] Furthermore, the J used in the second target manual steering angle calculation unit 65 within the steering ECU 204 ｃ k2 and c2 may be changed according to the situation. For example, in a situation where emergency avoidance should be performed, the second target manual steering angle calculation unit 65 may use J ｃ By performing control that changes k2 and c2, it becomes possible to improve the steering response to manual steering at specific frequencies.

[0089] Figure 5 is a block diagram illustrating the electrical configuration of a modified example of the reaction force ECU 203. In Figure 5, parts corresponding to the parts in Figure 2 are denoted by the same reference numerals as in Figure 2.

[0090] In the reaction force ECU 203A shown in Figure 5, the configuration of the microcomputer 40A differs from that of the reaction force ECU 203 in Figure 2. In the reaction force ECU 203A shown in Figure 5, instead of the selector 43 in Figure 2, the first target steering angle θ is used. ａｒ１ , second target steering angle θ ａｒ２ and the first target manual steering angle θ ｍｒ A selector 43A is provided for selecting one of the following. Then, one target steering angle (θ) selected by the selector 43A is ａｒ１ , θ ａｒ２ or θ ｍｒ ) is the target integrated steering angle θ in Figure 2. ｉｒ Instead, the force is now supplied to the first angle control unit 49. Therefore, the reaction force ECU 203A shown in Figure 5 does not have the target integrated steering angle calculation unit 48 shown in Figure 2.

[0091] The first angle control unit 49 sets one target steering angle (θ) selected by the selector 43A. ａｒ１ , θ ａｒ２ or θ ｍｒ Based on this, the reaction motor 13 is angle-controlled. Specifically, the first angle control unit 49 controls the actual steering angle θ ｒｐ (The rotation angle of the second axis 9) is one target steering angle (θ) selected by the selector 43A. ａｒ１ , θ ａｒ２ or θ ｍｒThe drive circuit 31 is controlled to follow the movement.

[0092] The vehicle motion domain ECU 202 sets the first target steering angle θ ａｒ１ , second target steering angle θ ａｒ２ and the first target manual steering angle θ ｍｒ Select flag F for selecting one of the following: ｓ Set the select flag F set by the vehicle motion domain ECU 202. ｓ This is provided to the selector 43A in the reaction force ECU 203 via the in-vehicle network.

[0093] Selector 43A has select flag F ｓ Based on this, the first target steering angle θ ａｒ１ , second target steering angle θ ａｒ２ and the first target manual steering angle θ ｍｒ Choose one of the following.

[0094] Selector 43A selects the second target steering angle (converted steering angle value) θ ａｒ２ If selected, steering angle θ ｒｐ The steering angle θ is ｓｐ The value is determined by and VGR. In this case, the steering angle θ ｒｐ The steering angle θ ｓｐ It is related to the first target steering angle θ by the selector 43. ａｒ１ If selected (first target steering angle θ) ａｒ１ (Including the case where is set to zero), or the first target manual steering angle θ by selector 43 ｍｒ If selected, steering angle θ ｒｐ The steering angle θ ｓｐ It cannot be related to the steering angle. Therefore, in this modified example as well, it is possible to control the steering angle independently of the steering angle.

[0095] Instead of the configuration enclosed by the dashed line X in the reaction force ECU 203 in Figure 2 and the reaction force ECU 203A in Figure 5 (a configuration consisting of a target reaction force torque calculation unit 44, a torque deviation calculation unit 45, a PD control unit 46, and a first target manual angle calculation unit 47), a configuration 70 as shown in Figure 6 may be used.

[0096] Configuration 70 includes a target assist torque setting unit 71, a subtraction unit 72, and a third target manual steering angle calculation unit 73. The third target manual steering angle calculation unit 73 is an example of the "first target manual steering angle calculation unit" in this disclosure.

[0097] The target assist torque setting unit 71 sets the vehicle speed V and the torsion bar torque T. ｔｂ Based on this, the target assist torque T ａ Set the target assist torque T. ａ Torsion bar torque T ｔｂ For positive values ​​of , it takes a positive value, and the torsion bar torque T ｔｂ For negative values ​​of T, it is set to take a negative value. Also, the target assist torque T ａ Torsion bar torque T ｔｂ The absolute value of is set to increase as the absolute value of increases and the vehicle speed V decreases.

[0098] The subtraction unit 72 controls the target assist torque T ａ From there, the rack axial force F is supplied from the steering ECU 204. ｒ By subtracting this, the feedforward control torque T ａｆｆ Perform the calculation.

[0099] The third target manual steering angle calculation unit 73 is T in equation (2) ｔｂ Torsion bar torque T detected by torque sensor 11 ｔｂ Substitute N1・T ｍ The feedforward controlled torque T calculated by the subtraction unit 72 ａｆｆ By substituting the values, substituting the predetermined third spring constant k3 as k, and substituting the predetermined third viscous damping coefficient c3 as c, and solving the differential equation (2), the rotation angle θ of the lower column can be found. ｃ The third target manual steering angle calculation unit 73 then calculates the rotation angle θ of the lower column obtained. ｃ The first target manual steering angle θ ｍｒ Set it as follows.

[0100] In other words, the third target manual steering angle calculation unit 73 is N1・T in equation (2). ｍ , θ ｃ , k and c are Tａｆｆ , θ ｍｒ By solving the differential equation (5) below, with k3 and c3 substituted, the first target manual steering angle θ can be found. ｍｒ Perform the calculation.

[0101] J ｃ d ２ θ ｍｒ / dt ２ = T ｔｂ +T ａｆｆ -k³・θ ｍｒ -c³(dθ) ｍｒ / dt) ... (5)

[0102] While embodiments of this disclosure have been described in detail, these are merely examples used to illustrate the technical content of this disclosure, and this disclosure should not be construed as being limited to these examples. The scope of this disclosure is limited only to the attached claims.

[0103] 13...Reaction motor, 11...Torque sensor, 19...Steering motor, 41, 61...Rotation angle calculation unit, 42, 62...Reduction ratio division unit, 43, 43A...Selector, 44...Target drive torque calculation unit, 45...Torque deviation calculation unit, 46...PD control unit, 47...First target manual steering angle calculation unit, 48...Target integrated steering angle calculation unit, 48...First angle control unit, 63...Second target steering torque calculation unit, 64...Rack axis force estimation unit, 65...Second target manual steering angle calculation unit, 66...Target integrated steering angle calculation unit, 67...Second angle control unit, 71...Target assist torque setting unit, 72...Subtraction unit, 73...Third target manual steering angle calculation unit, 201...ADAS domain ECU, 202...Vehicle motion domain ECU, 203...Reaction force ECU, 204...Steering ECU

Claims

1. A steering device comprising: a steering mechanism mechanically separated from a steering member for steering the steering wheels of a vehicle; a reaction force motor for applying reaction force torque to the steering member; a steering motor for driving the steering mechanism; a reaction force motor control device for controlling the reaction force motor; and a steering motor control device for controlling the steering motor, wherein the reaction force motor control device includes a first target manual steering angle calculation unit for calculating a first target manual steering angle based on steering torque input by a driver, and a steering control unit for controlling the reaction force motor using the first target manual steering angle; and the steering motor control device includes a second target manual steering angle calculation unit for calculating a second target manual steering angle based on steering torque input by a driver, and a steering control unit for controlling the steering motor using the second target manual steering angle.

2. The steering device according to claim 1, wherein the steering mechanism includes a rack shaft, the steering device includes a rack shaft force estimation unit that estimates the rack shaft force acting on the rack shaft via the steering wheels, the reaction force motor control device includes a target driver torque calculation unit that calculates a target driver torque to be input by the driver to the steering member using the rack shaft force estimated by the rack shaft force estimation unit, and a feedback control torque calculation unit that calculates a feedback control torque by performing torque feedback control so that the steering torque follows the target driver torque, and the first target manual steering angle calculation unit calculates the first target manual steering angle based on the feedback control torque and the steering torque.

3. The steering device has a function to vary a virtual gear ratio representing the ratio of the steering angle to the steering angle, the reaction motor control device includes a selection unit that selects either a first target steering angle provided by a control device higher than the reaction motor control device and the steering motor control device, and a second target steering angle calculated using the actual steering angle and the gear ratio, or a target integrated steering angle which is the sum of the target steering angle provided by the higher control device and the second target manual steering angle and the gear ratio, and a target integrated steering angle calculation unit that calculates the target integrated steering angle by adding the target steering angle selected by the selection unit to the first target manual steering angle, and the steering control unit is configured to control the reaction motor using the target integrated steering angle, as described in claim 1.

4. The steering device has a function to vary a virtual gear ratio representing the ratio of the steering angle to the steering angle, the reaction motor control device includes a selection unit that selects one of the following: a first target steering angle provided by a control device higher than the reaction motor control device and the steering motor control device, a second target steering angle calculated using the actual steering angle and the gear ratio, or a target integrated steering angle which is the sum of the target steering angle and the second target manual steering angle provided by the higher control device and the gear ratio, and the first target manual steering angle, and the steering control unit is configured to control the reaction motor using the one target steering angle selected by the selection unit, as described in claim 1.

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