Control device and steering device

Abstract

The invention provides a control device and a steering device. This control device is mounted on a steer-by-wire steering device mounted on a vehicle, and is provided with: a steering mechanism having a steering wheel to be steered by a steer; the steering mechanism is provided with a first steering wheel and a second steering wheel; and a steering-side motor that drives the steering mechanism, the control device being provided with a steering-side control unit that controls a control object including the steering-side motor. The steering-side control unit has a model tracking control unit that generates a correction torque that corrects an input torque input to the control object on the basis of an output of the control object and a nominal model based on the configuration of the control object. The model tracking control unit is configured so as to constrain the transfer function of the control object to the transfer function of the nominal model in a frequency band in which the gain in the gain characteristic of the complementary sensitivity function with respect to the modeling error between the control object and the nominal model is approximately 1.

Description

Technical Field

[0001] The invention relates to a control device and a steering device. Background Art

[0002] Conventionally, there are known separate-type power steering devices that are not mechanically connected and so-called steer-by-wire steering devices (for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent No. 4639500

[0004] In the above-mentioned steering device, further improvement of steering performance is desired. Summary of the invention

[0005] The present invention has been made in view of the above circumstances, and one object of the present invention is to provide a control device capable of improving the steering performance of a steering device and a steering device having such a control device.

[0006] One embodiment of the present invention is a control device, which is mounted on a steering device of a steer-by-wire type, the steering device being mounted on a vehicle, and comprising: a steering mechanism having a steering wheel for a steerer to steer; a steering mechanism having a first steering wheel and a second steering wheel; and a steering-side motor that drives the steering mechanism, wherein the control device comprises a steering-side control unit that controls a control object including the steering-side motor. The steering-side control unit comprises a model tracking control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on a structure of the control object. The model tracking control unit is configured to constrain a transfer function of the control object to a transfer function of the nominal model in a frequency band where a gain is approximately 1 in a gain characteristic of a complementary sensitivity function with respect to a modeled error between the control object and the nominal model.

[0007] According to one aspect of the present invention, the steering performance of the steering device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a diagram schematically showing the steering device in the first embodiment.

[0009] Figure 2 This is a diagram schematically showing a part of the steering mechanism in the first embodiment.

[0010] Figure 3 This is a diagram schematically showing a part of the first steering motor in the first embodiment.

[0011] Figure 4AIt is a diagram schematically showing a part of the first steering motor and a part of the first steering control unit in the first embodiment.

[0012] Figure 4B It is a diagram schematically showing a part of the second steering motor and a part of the second steering control unit in the first embodiment.

[0013] Figure 5 It is a block diagram showing the configuration of the control device in the first embodiment.

[0014] Figure 6 : is a block diagram showing the structure of the command value generating unit in the first embodiment.

[0015] Figure 7 This is a block diagram showing a partial configuration of a command value generating unit in the first embodiment.

[0016] Figure 8 It is a graph showing the relationship between the vehicle response characteristics and the feeling of the steersman when steering the vehicle.

[0017] Fig. 9 It is a block diagram showing the configuration of the coordination control unit in the first embodiment.

[0018] Fig.10 : is a graph showing the gain characteristic of the frequency region setting unit in the first embodiment.

[0019] Fig.11 This is a block diagram showing the configuration of a steering reaction force control unit in the first embodiment.

[0020] Fig. 12A This is a graph showing an example of the relationship between the steering torque and the self-aligning torque.

[0021] Fig. 12B This is a graph showing an example of the relationship between the assist torque and the steering torque.

[0022] Fig.13 This is a block diagram showing a partial configuration of a first steering control unit in the first embodiment.

[0023] Fig.14 This is a diagram showing a simplified model of the first control target in the first embodiment.

[0024] Fig.15 Graphs illustrating gain characteristics of the complementary sensitivity function and gain characteristics of the inverse of the modeling error between the transfer function of the first controlled object and the transfer function of the first nominal model.

[0025] Fig.16This is a block diagram showing a partial configuration of a second steering control unit in the first embodiment.

[0026] Fig.17 It is a diagram schematically showing a steering device in a second embodiment.

[0027] Description of symbols

[0028] 10: Steering mechanism; 11: Steering wheel; 20, 220: Steering mechanism; 21: First steering wheel; 22: Second steering wheel; 23d, 23e, 41a, 42a: Bushing; 31: First steering motor; 32: Second steering motor; 33: First steering motor; 34: Second steering motor; 35b, 35c: Stator; 36: Coil; 37: Coil group; 50, 250: Control device; 51: First steering control unit; 52: Second steering control unit; 53: First steering control unit; 54: Second steering control unit; 56a, 56b: coordination control unit; 57a, 57b: steering reaction force control unit; 58, 59: inverter circuit; 63: first model tracking control unit; 65a: first control object; 65b: second control object; 68: second model tracking control unit; 100, 200: steering device; CT1: coordination control (first control); CT2: non-interference control (second control); f: steering frequency; J: center axis; NM1: first nominal model; NM2: second nominal model; T f1 , T f2 : Correction torque; T m1 , T m2 , T m2L , T m2R : Correction interference torque; T r1 : First input torque; T r2 : The second input torque; θ h : Steering angle; θ s : output angle; ω1: cut-off frequency; ω r : Resonance frequency. DETAILED DESCRIPTION

[0029] <First embodiment>

[0030] Figure 1 The steering device 100 of the present embodiment shown in FIG. 1 is mounted on a vehicle. The steering device 100 is a steer-by-wire steering device. Figure 1As shown, the steering device 100 includes: a steering mechanism 10 including a steering wheel 11 for a steerer to steer; a steering mechanism 20 including a first steering wheel 21 and a second steering wheel 22; a first steering side motor 31; a second steering side motor 32; a first steering side motor 33; a second steering side motor 34; a control device 50; a steering torque sensor 81; a steering angle sensor 82; a first rotation sensor 83; a second rotation sensor 84; a first battery 85a; and a second battery 85b. The control device 50 includes a first steering side control unit 51, a second steering side control unit 52, a first steering side control unit 53, and a second steering side control unit 54. The first battery 85a supplies power to the first steering side control unit 51 and the first steering side control unit 53. The second battery 85b supplies power to the second steering side control unit 52 and the second steering side control unit 54.

[0031] When the driver, i.e., the steerer, who drives the vehicle, steers the steering mechanism 10 via the steering wheel 11, the first steering motor 33 and the second steering motor 34 are driven by the control device 50, and the steering mechanism 20 is driven by the first steering motor 33 and the second steering motor 34. By driving the steering mechanism 20, the angle of the first steering wheel 21 and the angle of the second steering wheel 22 are changed, and the traveling direction of the vehicle is changed. The first steering wheel 21 and the second steering wheel 22 are a pair of tires on the front side of the vehicle. The angle of the first steering wheel 21 and the angle of the second steering wheel 22 are steering angles.

[0032] The steering mechanism 10 has a steering wheel 11, an input shaft 12, an output shaft 13, a torsion bar 14, and a first transmission mechanism 15. The input shaft 12 is a shaft extending from the steering wheel 11 steered by the steersman. The output shaft 13 is connected to the input shaft 12 via the torsion bar 14. The first transmission mechanism 15 is connected to the output shaft 13. The input shaft 12 and the output shaft 13 are coaxially arranged. The input shaft 12 and the output shaft 13 can rotate around the same center axis. In the following description, the imaginary axis passing through the common center axis of the input shaft 12 and the output shaft 13 is referred to as the rotation axis R. The input shaft 12 and the output shaft 13 can rotate relative to each other within the range in which the torsion bar 14 can twist. The torsion bar 14 connects the input shaft 12 and the output shaft 13. The torsion bar 14 can twist around the rotation axis R. The rotation angle of the input shaft 12 around the rotation axis R is the steering angle θ of the steering wheel 11 h . Steering angle θ h The output angle θ is detected by the steering angle sensor 82. The rotation angle of the output shaft 13 around the rotation axis R is the output angle θ. s .

[0033] The first transmission mechanism 15 connects the output shaft 13 to the first steering motor 31 and the second steering motor 32. The first transmission mechanism 15 transmits the rotational torque of the first steering motor 31 and the rotational torque of the second steering motor 32 to the output shaft 13 as torque around the rotation axis R. The first transmission mechanism 15 is, for example, a speed reduction mechanism including a worm gear. The output angle θ is controlled by rotating the output shaft 13 through the first transmission mechanism 15 using the first steering motor 31 and the second steering motor 32. s , thereby controlling the torsion amount of the torsion bar 14 around the rotation axis R. Thus, the force around the rotation axis R transmitted from the torsion bar 14 via the input shaft 12 to the steering wheel 11 can be controlled, and the steering reaction force transmitted to the steersman via the steering wheel 11 can be controlled. The steering reaction force is equal to the steering torque T h .

[0034] Steering torque T h The steering torque sensor 81 detects the steering torque T by detecting the amount of torsion of the torsion bar 14 around the rotation axis R. h . Steering torque T h is the torsion bar torque generated in the torsion bar 14, and is the torsion moment about the rotation axis R. In the present embodiment, the rotation angle of the output shaft 13, that is, the output angle θ can be detected by the steering torque sensor 81 and the steering angle sensor 82. s .

[0035] The steering mechanism 20 includes a first steering wheel 21, a second steering wheel 22, a steering linkage 23, steering knuckle arms 24a, 24b, and second transmission mechanisms 25a, 25b. The steering linkage 23 includes a rack shaft 23c and tie rods 23a, 23b. The rack shaft 23c extends in the left-right direction of the vehicle, that is, in the vehicle width direction. Figure 2 As shown in FIG. 1 , bushings 23d and 23e are provided on the rack shaft 23c on the side where the first steering wheel 21 is arranged. Although not shown in the figure, the rack shaft 23c on the side where the second steering wheel 22 is arranged is also provided with bushings in the same manner as the rack shaft 23c on the side where the first steering wheel 21 is arranged. Figure 2 In FIG. 1 , the elasticity and viscosity of the first steering wheel 21 are represented as a bushing element RB between the road surface RS and the first steering wheel 21 .

[0036] like Figure 1As shown, the first steering wheel 21 is connected to one end of the rack shaft 23c via the tie rod 23a and the knuckle arm 24a. The second steering wheel 22 is connected to the other end of the rack shaft 23c via the tie rod 23b and the knuckle arm 24b. The second transmission mechanism 25a connects the rack shaft 23c to the first steering side motor 33. The second transmission mechanism 25b connects the rack shaft 23c to the second steering side motor 34. The second transmission mechanism 25a is connected to a portion of the rack shaft 23c on the side close to the first steering wheel 21 in the vehicle width direction. The second transmission mechanism 25b is connected to a portion of the rack shaft 23c on the side close to the second steering wheel 22 in the vehicle width direction. The second transmission mechanism 25a is a speed reduction mechanism having a pinion meshing with the rack shaft 23c. The second transmission mechanism 25b is a speed reduction mechanism having a pinion meshing with the rack shaft 23c.

[0037] like Figure 2 As shown, the first steering wheel 21 is provided with a suspension 40. The suspension 40 includes a transverse link 41 and a tie rod 42. A bushing 41a is provided on the transverse link 41. A bushing 42a is provided on the tie rod 42. Although not shown in the figure, the second steering wheel 22 is also provided with a suspension 40 in the same manner as the first steering wheel 21.

[0038] The first steering motor 31 is controlled by the first steering motor 31. The second steering motor 32 is controlled by the second steering motor 32. The first steering motor 31 and the second steering motor 32 can drive the steering mechanism 10. The first steering motor 33 is controlled by the first steering control unit 53. The second steering motor 34 is controlled by the second steering control unit 54. The first steering motor 33 and the second steering motor 34 drive the steering mechanism 20.

[0039] like Figure 3 As shown, the first steering motor 33 has a rotor 35a and a stator 35b. The rotor 35a is rotatable around the center axis J. In the following description, the direction in which the center axis J extends is referred to as "axial direction", the radial direction centered on the center axis J is referred to as "radial direction", and the circumferential direction centered on the center axis J is referred to as "circumferential direction". The stator 35b is located radially outside the rotor 35a. The stator 35b surrounds the rotor 35a. The stator 35b has a plurality of coils 36 arranged over the entire circumference in the circumferential direction. In the present embodiment, 12 coils 36 are provided. The 12 coils 36 are composed of 4 U-phase coils U1a, U1b, U2a, U2b, 4 V-phase coils V1a, V1b, V2a, V2b, and 4 W-phase coils W1a, W1b, W2a, W2b.

[0040] like Figure 4AAs shown, the stator 35b in the first steering motor 33 has a plurality of coil groups 37. In the present embodiment, the coil group 37 in the first steering motor 33 includes two coil groups 37a of the first system and a second coil group 37b of the second system. The first coil group 37a of the first system includes two U-phase coils U1a and U1b, two V-phase coils V1a and V1b, and two W-phase coils W1a and W1b. The second coil group 37b of the second system includes two U-phase coils U2a and U2b, two V-phase coils V2a and V2b, and two W-phase coils W2a and W2b. That is, two coils 36 are provided in one phase of each system. The two coils 36 of each phase of each system are connected to each other by a jumper wire 36b. In the first coil group 37a of the first system, the U-phase coils U1a and U1b, the V-phase coils V1a and V1b, and the W-phase coils W1a and W1b are connected to each other by Y connection. In the second coil group 37 b of the second system, the U-phase coils U2 a and U2 b , the V-phase coils V2 a and V2 b , and the W-phase coils W2 a and W2 b are connected to each other by Y connection.

[0041] like Figure 3 As shown, in the first steering motor 33, the first coil groups 37a and 37b of different systems are arranged rotationally symmetrically around the central axis J. Thus, the redundancy of the first steering motor 33 can be ensured. That is, even if a malfunction occurs in any of the coil groups 37 of the plurality of systems, the first steering motor 33 can be appropriately driven using the coil groups 37 of the other systems.

[0042] In this specification, “the coil groups have different systems” includes the case where current is supplied independently to each coil group system. That is, three-phase AC current is supplied independently to each of the first coil group 37a and the second coil group 37b.

[0043] In the present embodiment, the first coil group 37a and the second coil group 37b are arranged symmetrically with each other around the central axis J. That is, when the first coil group 37a is rotated 180° around the central axis J, the positions of the coils 36 of each phase in the first coil group 37a and the positions of the coils 36 of each phase in the second coil group 37b are respectively consistent in the circumferential direction. In this way, by arranging the first coil group 37a and the second coil group 37b symmetrically with each other around the central axis J, it is easy to arrange the coils 36 of the first coil group 37a and the coils 36 of the second coil group 37b of the same phase separately from each other, and it is easy to suppress the mutual inductance generated between the first coil group 37a and the second coil group 37b to be small. Therefore, it is easy to improve the magnetic independence of the two coil groups 37 of the different systems. Therefore, it is easy to improve the controllability of torque fluctuations and the like using model tracking control described later.

[0044] In addition, as long as the plurality of coil groups 37 are arranged rotationally symmetrically around the central axis J, they can be symmetrical in any order. For example, in the case where three coil groups 37 are provided, the three coil groups 37 can also be arranged three times symmetrically around the central axis J. In this case, when one coil group 37 is rotated 120° around the central axis J, the positions of the coils 36 of each phase in the one coil group 37 are respectively consistent with the positions of the coils 36 of each phase in the other coil group 37 in the circumferential direction. In this case, as in the case of the two coil groups 37 described above, it is easy to suppress the mutual inductance generated between the three coil groups 37 to be small. Therefore, it is easy to improve the magnetic independence in the three coil groups 37 of different systems. Therefore, it is easy to improve the controllability of torque fluctuations and the like using model tracking control described later.

[0045] In the present embodiment, the coils 36 in the first coil group 37a of the first system and the coils 36 in the second coil group 37b of the second system are arranged radially across the central axis J. The coils 36 of the first coil group 37a and the coils 36 of the second coil group 37b arranged radially across the central axis J are coils of the same phase as each other. That is, for example, the U-phase coil U1a of the first coil group 37a and the U-phase coil U2a of the second coil group 37b are arranged radially across the central axis J, the V-phase coil V1a of the first coil group 37a and the V-phase coil V2a of the second coil group 37b are arranged radially across the central axis J, and the W-phase coil W1a of the first coil group 37a and the W-phase coil W2a of the second coil group 37b are arranged radially across the central axis J.

[0046] A lead wire 36a extends axially from each coil 36. The lead wire 36a extending from the U-phase coil U1a in the first coil group 37a is connected to the U-phase bus bar 38Ua via the connection terminal 38Us. The lead wire 36a extending from the V-phase coil V1a in the first coil group 37a is connected to the V-phase bus bar 38Va via the connection terminal 38Vs. The lead wire 36a extending from the W-phase coil W1a in the first coil group 37a is connected to the W-phase bus bar 38Wa via the connection terminal 38Ws. The lead wire 36a extending from the U-phase coil U1b in the first coil group 37a, the lead wire 36a extending from the V-phase coil V1b, and the lead wire 36a extending from the W-phase coil W1b are connected to the neutral point bus bar 39a via the connection terminal 39Sa.

[0047] The lead wire 36a extending from the U-phase coil U2a in the second coil group 37b is connected to the U-phase bus bar 38Ub via the connection terminal 38Us. The lead wire 36a extending from the V-phase coil V2a in the second coil group 37b is connected to the V-phase bus bar 38Vb via the connection terminal 38Vs. The lead wire 36a extending from the W-phase coil W2a in the second coil group 37b is connected to the W-phase bus bar 38Wb via the connection terminal 38Ws. The lead wire 36a extending from the U-phase coil U2b in the second coil group 37b, the lead wire 36a extending from the V-phase coil V2b, and the lead wire 36a extending from the W-phase coil W2b are connected to the neutral point bus bar 39b via the connection terminal 39Sb.

[0048] The structure of the second steering motor 34 is the same as that of the first steering motor 33. Figure 4B As shown in FIG. 1 , the second steering motor 34 includes a stator 35c. The stator 35c of the second steering motor 34 includes a plurality of coil groups 37, similarly to the stator 35b of the first steering motor 33. In the present embodiment, the coil group 37 of the second steering motor 34 includes two coil groups 37a of the first system and a second coil group 37b of the second system. Although not shown in the figure, the coil groups 37 of different systems in the second steering motor 34 are arranged rotationally symmetrically around the central axis of the second steering motor 34, similarly to the coil groups 37 of the first steering motor 33. For example, in the second steering motor 34, the first coil group 37a and the second coil group 37b are arranged twice symmetrically around the central axis J. Thus, similarly to the first steering motor 33, the redundancy of the second steering motor 34 can be ensured.

[0049] The first output angle θ which is the rotation angle of the first steering motor 33 g1 The second output angle θ which is the rotation angle of the second steering motor 34 is detected by the first rotation sensor 83. g2 The rotation angle of each steering motor is the rotation angle of the rotor 35a in each steering motor around the central axis R. The first output angle θ g1 The second output angle θ is equal to the rotation angle of the pinion gear attached to the output shaft of the first steering motor 33, that is, the pinion gear absolute angle. g2 The rotation angle of the pinion gear mounted on the output shaft of the second steering motor 34, that is, the absolute angle of the pinion gear is equal. Figure 4A As shown, the first output angle θ detected by the first rotation sensor 83 g1 The data is input to a first processor 53a described later in the first steering control unit 53. Figure 4B As shown, the second output angle θ detected by the second rotation sensor 84 isg2 The information is input to a second processor 54 a described later in the second steering control unit 54 .

[0050] The structures of the first steering motor 31 and the second steering motor 32 may be the same as or different from the structures of the first steering motor 33. The first steering motor 31 and the second steering motor 32 may have a plurality of coil groups or only one coil group.

[0051] <Control device>

[0052] The control device 50 controls each part of the steering device 100. In the present embodiment, the control device 50 controls the first steering side motor 33 and the second steering side motor 34 to control the steering mechanism 20, and controls the first steering side motor 31 and the second steering side motor 32 to control the steering reaction force transmitted to the steerer via the steering wheel 11. The first steering side control unit 51 controls the first steering side motor 31. The second steering side control unit 52 controls the second steering side motor 32. The first steering side control unit 53 controls the first steering side motor 33. The second steering side control unit 54 controls the second steering side motor 34. The first steering side control unit 51 and the first steering side control unit 53 can communicate with each other. The second steering side control unit 52 and the second steering side control unit 54 can communicate with each other. Therefore, in the steering device 100 of the steer-by-wire type in which the steering mechanism 10 and the steering mechanism 20 are not mechanically connected, the steering mechanism 10 and the steering mechanism 20 can be appropriately controlled.

[0053]

Steering side control unit

[0054] like Figure 5 As shown in FIG. 1 , the first steering control unit 51 includes a command value generating unit 55a, a coordination control unit 56a, and a steering reaction force control unit 57a. The second steering control unit 52 includes a command value generating unit 55b, a coordination control unit 56b, and a steering reaction force control unit 57b. That is, the control device 50 includes command value generating units 55a, 55b, coordination control units 56a, 56b, and steering reaction force control units 57a, 57b.

[0055] (Command value generation unit)

[0056] The command value generating unit 55a generates a steering motor angle command value θ to be sent to the first steering control unit 53. gr1 The command value generating unit 55b generates a steering motor angle command value θ to be sent to the second steering control unit 54. gr2 . Steering motor angle command value θ gr1 is the first output angle θ of the first steering motor 33 g1 The target value of the steering motor angle command value θgr2 is the second output angle θ of the second steering motor 34 g2 The target value of the steering motor angle command value θ gr1 The steering motor angle command value θ is equal to the rotation angle of the pinion gear attached to the output shaft of the first steering motor 33, that is, the target value of the pinion gear absolute angle. gr2 The command value generating unit 55b generates the steering motor angle command value θ to be sent to the second steering control unit 54. gr2 In the following description, regarding the command value generating unit 55b, the description of the same configuration as the command value generating unit 55a may be omitted.

[0057] like Figure 6 As shown in FIG. 1 , the command value generating unit 55a includes a yaw rate phase compensating unit 55c, a yaw rate stabilizing compensating unit 55d, and a VGR controlling unit 55e. The yaw rate phase compensating unit 55c is a unit that realizes a desired transfer characteristic based on a model of a stabilized yaw rate γ(V). c The yaw rate γ(V) in the vehicle is a parameter indicating the change in the yaw angle, which is the deflection angle in the left-right direction of the vehicle. In other words, the yaw rate γ(V) is the angular velocity when the vehicle vibrates in the left-right direction. V is the vehicle's running speed, that is, the vehicle speed. The transfer function Y1(s) of the yaw rate phase compensation unit 55c of the vehicle is expressed by the following equation (1).

[0058]

[0059] Where s is the Laplace transform, ω n is the natural frequency of the yaw rate γ(V), G θ γ (s) is the steering angle θ h The transfer function to the yaw rate γ(V), G θ γ (0) is G when s=0 θ γ (s) value, T γ (V) is a function of the vehicle speed V, which is G θ γ (s) time constant.

[0060] The yaw rate stabilization compensating unit 55d adjusts the first output angle θ which is the rotation angle of the first steering motor 33. g1 Feedback control is performed to make the steering angle θ hThe transfer characteristic to the yaw rate γ(V) is approximated to the first-order transfer characteristic, thereby stabilizing the yaw rate γ(V). The yaw rate γ(V) is input to the yaw rate stabilization compensation unit 55d. Figure 7 As shown in FIG. 1 , the yaw rate stabilization compensator 55d includes a differentiator 55f, a gain adjuster 55g, a compensator 55h, and a subtractor SU5. The gain adjuster 55g multiplies the value of the yaw rate γ(V) differentiated by the differentiator 55f by a gain K. γ (V) The output from the gain adjuster 55g is input to the compensation unit 55h.

[0061] The transfer function Y2(s) of the compensation unit 55h is expressed by the following equation (2).

[0062]

[0063] The output from the compensator 55h is input to the subtractor SU5. The subtractor SU5 subtracts the output from the compensator 55h from the output from the yaw rate phase compensator 55c. The subtractor SU5 outputs the steering motor angle command value θ. gr .like Figure 6 As shown in FIG. 1 , the steering motor angle command value θ output from the subtractor SU5 is gr It is input to the VGR control unit 55e.

[0064] Here, from the steering angle θ h Transfer function G to yaw rate γ(V) θ γ (s) is represented by the following formula (3).

[0065]

[0066] Among them, ξ(V) is a function of the vehicle speed V and is the attenuation coefficient of the yaw rate γ(V).

[0067] If the transfer function G represented by the above equation (3) is θ γ Multiplying (s) by the right term of equation (2) yields the following equation (4).

[0068]

[0069] When the transfer function when the value output from the gain adjuster 55g is fed back to the above-mentioned equation (4) is summarized, it becomes the left term of the following equation (5).

[0070]

[0071] In the left term of the above equation (5), if {2ξ(V)+K γ(V)}=2, the left term of equation (5) becomes the right term of equation (5), and it can be seen that it becomes a stable transfer function with an attenuation coefficient of 1. From this, it can be seen that if {2ξ(V)+K γ K is determined by the method of (V)}=2 γ (V), then the steering angle θ h Transfer function G to yaw rate γ(V) θ γ (s) Stabilization. In this embodiment, the yaw rate γ(V) is multiplied by K for feedback. r The differentiator 55f and the gain adjuster 55g are provided based on the value obtained by (V)s, and the right term of the above equation (2) is respectively inserted between the gain adjuster 55g and the subtractor SU5 in the yaw rate phase compensator 55c and the yaw rate stabilization compensator 55d, thereby making the transfer function G θ γ (s) is stabilized like the right term of equation (5).

[0072] The part of the transfer function Y1(s) of the yaw rate phase compensator 55c shown in equation (1) other than the right term of equation (2) is (s+ω n ) 2 / (T c s+1). Therefore, in the transfer function obtained by multiplying the yaw rate phase compensator 55c and the yaw rate stabilization compensator 55d, (s+ω n ) 2 / (T c s+1) and the right term of formula (5), 1 / (s+ω n )2, the denominator cancels out, becoming 1 / (T c s+1). Thus, it is possible to change the steering angle θ h The transfer characteristic to the yaw rate γ(V) is approximately a first-order transfer characteristic. In the present embodiment, the steering angle θ input to the yaw rate phase compensator 55c is h The right term of the equation (2) included in the yaw rate phase compensator 55 c converts the yaw rate phase into the first output angle θ of the first steering motor 33. g1 The command value, the fed-back yaw rate γ(V) is converted into the first output angle θ by the compensation unit 55h g1 Therefore, the value output from the yaw rate stabilization compensation unit 55d becomes the first output angle θ g1 The steering motor angle command value θ of the command value gr .

[0073] In the yaw rate phase compensator 55c, the above-mentioned approximate first-order transfer function, 1 / (T c s+1) time constant T cis set to a desired value. This can improve the steering feel of the steerer when steering the steering wheel 11, so that the steerer can easily steer the vehicle. Specifically, the time constant T c For example, according to Figure 8 The relationship shown in the graph is used to determine the Figure 8 The relationship between the vehicle response characteristics and the steering feeling of the steerer is shown in FIG. Figure 8 In the figure, the horizontal axis represents the lateral acceleration time constant T a , the vertical axis represents the yaw rate time constant T b . Transverse acceleration time constant T a is the steering angle θ h The time constant in the transfer function of the acceleration to the lateral movement of the vehicle when turning. Yaw rate time constant T b is the steering angle θ h The yaw rate phase compensation unit 55c is, for example, based on Figure 8 The relationship between the curve graph is 1 / (T c s+1) time constant T c The value of is set to a value that makes it easy for the steerer to steer the vehicle. The yaw rate phase compensator 55c sets the time constant T c The value of is set to become Figure 8 The yaw rate time constant T in the “area of ​​good steering feeling” is shown as b The value of , that is, about 0.04 seconds or more and 0.10 seconds or less. Thus, the feeling felt by the steersman when steering the steering wheel 11 can be good.

[0074] The VGR control unit 55e sets a virtual gear ratio from the first steering motor 33 to the first steering wheel 21 and adjusts the steering motor angle command value θ gr part. Figure 6 As shown in FIG. 1 , the steering motor angle command value θ outputted from the yaw rate stabilization compensation unit 55d is inputted to the VGR control unit 55e. gr and the automatic return torque estimation value SAT h . Automatic return torque estimation value SAT h The estimated value of the total value of the self-aligning torque received by the steering mechanism 20 via the first steering wheel 21 and the second steering wheel 22. The self-aligning torque is a torque that acts on the steering wheel 11 in the direction of returning due to the elasticity of the first steering wheel 21 and the elasticity of the second steering wheel 22 that are twisted when the angle of the first steering wheel 21 and the angle of the second steering wheel 22 are changed by steering the steering wheel 11. In the present embodiment, the self-aligning torque estimated value SAT hThe first self-aligning torque estimated value SAT generated by the first steering wheel 21 estimated by the first steering control unit 53 is h1 The second self-aligning torque estimated value SAT generated by the second steering wheel 22 estimated by the second steering control unit 54 h2 The first self-aligning torque estimated value SAT h1 It is an estimated value including the disturbance of the reaction force of the first steering wheel 21. Second self-aligning torque estimated value SAT h2 It is an estimated value including the disturbance of the reaction force of the second steering wheel 22. First self-aligning torque estimated value SAT h1 The second self-aligning torque estimated value SAT is output from the first model following control unit 63 described later. h2 The signal is output from the second model tracking control unit 68 described later.

[0075] The VGR control unit 55e is similar to the case where the steering mechanism 10 and the steering mechanism 20 are mechanically connected, in order to realize that the steering angle is shifted due to the force received from the first steering wheel 21 and the second steering wheel 22, based on the self-aligning torque estimated value SAT h To correct the steering motor angle command value θ gr Specifically, the VGR control unit 55e calculates the corrected steering motor angle command value θ according to the following equation (6): gra .

[0076]

[0077] Among them, K s is a coefficient related to elasticity between the steering mechanism 10 and the steering mechanism 20 assuming that the steering mechanism 10 and the steering mechanism 20 are mechanically connected, and C s It is a coefficient related to viscosity between the steering mechanism 10 and the steering mechanism 20 when assuming that the steering mechanism 10 and the steering mechanism 20 are mechanically connected.

[0078] When the steering mechanism 10 is mechanically connected to the steering mechanism 20, the output shaft 13 in the steering mechanism 10 rotates according to the magnitude of the self-aligning torque when the steering mechanism 20 receives the self-aligning torque via the first steering wheel 21 and the second steering wheel 22. h / (K s +C s s) is equivalent to generating a value of SAT when the steering mechanism 10 is mechanically connected to the steering mechanism 20. h The output shaft 13 rotates by the self-aligning torque when the self-aligning torque is θ. gr Subtract the SAT h / (K s +C s s), the steering motor angle command value θ gr The correction is made to the value when the steering mechanism 10 and the steering mechanism 20 are mechanically connected, that is, the steering side motor angle command value θ gra . Thus, in the steering device 100 of the steer-by-wire method, the steering feeling felt by the helmsman who steers the steering wheel 11 can be made the same as that of a power steering device in which the steering mechanism 10 and the steering mechanism 20 are mechanically connected. Therefore, for example, it is possible to cause a moderate time delay in the movement of the vehicle relative to the steering of the steering wheel 11, and it is possible to suppress the responsiveness from steering the steering wheel 11 to the change in the angle of the first steering wheel 21 and the angle of the second steering wheel 22 from becoming too sensitive. Therefore, it is possible to improve the affinity of the steering performance of the steering device 100 with respect to the feeling of the helmsman, and it is possible for the helmsman to steer the steering wheel 11 easily. In addition, by adjusting K as an elastic element s and C as the sticky element s , the elasticity and viscosity between the steering mechanism 10 and the steering mechanism 20 that are virtually connected can be arbitrarily set. s and C s By adjusting the value to a value that makes it easier for the steersman to steer, the steersman can steer the steering wheel 11 more easily.

[0079] The VGR control unit 55e calculates the steering motor angle command value θ calculated by the above equation (6) gra Multiply the variable gear ratio VGR(θ gra , V) to calculate the steering motor angle command value θ gra1 That is, θ gra1 =θ gra ·VGR(θ gra , V) is established. Variable gear ratio VGR(θ gra , V) is a hypothetical gear ratio between the first steering motor 33 and the first steering wheel 21, which is determined according to the steering motor angle command value θ gra The variable that changes with the vehicle speed V. Variable gear ratio VGR (θ gra , V) according to the angle of the first steering wheel 21 relative to the steering angle θ when the steering wheel 11 is steered h How to change and set appropriately.

[0080] Here, the rotation angle of the first steering motor 33, that is, the first output angle θ g1 The angle of the first steering wheel 21 (steering angle) is not linearly related, and the change amount of the angle of the first steering wheel 21 is determined by the first output angle θ. g1 Specifically, for example, the first output angle θg1 The larger the value, the less likely the angle of the first steering wheel 21 will change. Therefore, if the steering motor angle command value θ is simply input to the first steering motor 33, gra , then the change in the angle of the first steering wheel 21 is determined by the rotation angle of the steering wheel 11, that is, the steering angle θ h The size of the steering wheel 11 may change, and the steersman may find it difficult to steer the steering wheel 11.

[0081] In contrast, for example, by changing the variable gear ratio VGR (θ gra , V) is set according to the steering angle θ h The steering motor angle command value θ is obtained. gra The relationship between the angle of the first steering wheel 21 and the rotation angle of the steering wheel 11 (steering angle θ h ) changes in proportion. Thus, the steersman can steer the steering wheel 11 easily.

[0082] In addition, for example, when the steering wheel 11 is rotated greatly to change the traveling direction of the vehicle suddenly, it is sometimes preferable that the angle of the first steering wheel 21 changes more greatly as the rotation angle of the steering wheel 11 increases. gra , V) is set to the following variables: gra When the steering motor angle command value θ is greater than a certain value, gra The larger the value is, the greater the change in the angle of the first steering wheel 21 is relative to the steering motor angle command value θ. gra The greater the change in the steering wheel 11, the greater the change in the first steering wheel 21, that is, the steering angle, can be changed. Thus, for example, when the steerer wants to change the direction of travel of the vehicle suddenly to perform an emergency evasive action, the direction of travel of the vehicle can be appropriately changed.

[0083] The steering motor angle command value θ outputted from the VGR control unit 55e is gra1 is the output value output from the command value generating unit 55a. Figure 5 As shown in the figure, the steering motor angle command value θ gra1 The signal is input to the first steering control unit 53 .

[0084] The command value generating unit 55b generates the steering motor angle command value θ to be input to the second steering control unit 54 in the same manner as the command value generating unit 55a described above. gra2 . Steering motor angle command value θ gra2 is the second output angle θ which is the rotation angle of the second steering motor 34. g2The command value.

[0085] (Coordination and Control Department)

[0086] The coordination control units 56a and 56b perform calculations for coordination control of the first steering motor 33 and the second steering motor 34. In the following description, the coordination control units 56a and 56b are used as representatives, and the coordination control unit 56a is described, and the description of the same configuration of the coordination control unit 56b as that of the coordination control unit 56a is sometimes omitted.

[0087] like Fig. 9 As shown in FIG. 1 , the cooperative control unit 56a includes a compensation torque calculation unit 56c and a frequency region setting unit 56d. The first self-aligning torque estimation value SAT outputted from the first steering control unit 53 is inputted to the compensation torque calculation unit 56c. h1 and the second self-aligning torque estimated value SAT outputted from the second steering control unit 54 h2 .

[0088] First self-aligning torque estimated value SAT h1 The second self-aligning torque estimated value SAT h2 The sum of the values ​​of the self-aligning torque estimation value SAT h The total value of the torque required to drive the steering mechanism 20 can be considered as the total value of the motor torques required to be output by the first steering motor 33 and the second steering motor 34. Here, the first self-aligning torque estimation value SAT including the reaction force of the first steering wheel 21 is h1 The second self-aligning torque estimated value SAT including the reaction force of the second steered wheel 22 can be regarded as the value of the motor torque required by the first steered motor 33 which is closer to the first steered wheel 21 than the second steered motor 34. h2 It can be regarded as the value of the motor torque required in the second steering motor 34 which is closer to the second steering wheel 22 than the first steering motor 33. Since the reaction force received from the first steering wheel 21 and the reaction force received from the second steering wheel 22 are often different from each other, the first self-aligning torque estimated value SAT is h1 The second self-aligning torque estimated value SAT h2 In this case, the motor torque of the first steering motor 33 is different from the motor torque of the second steering motor 34. Therefore, a deviation in motor torque occurs between the first steering motor 33 and the second steering motor 34, and the load on the other steering motor becomes larger than that on one steering motor, so that the heat generated by the other steering motor may be larger than that of the one steering motor.

[0089] As long as the first self-aligning torque estimation value SAT can be increased by the output of the two steering motorsh1 The second self-aligning torque estimated value SAT h2 The summed torque, i.e., the self-aligning torque estimation value SAT h Therefore, in order to eliminate the difference between the motor torque of the first steering motor 33 and the motor torque of the second steering motor 34, the motor torque of each steering motor only needs to be equal to the first self-aligning torque estimated value SAT. h1 The second self-aligning torque estimated value SAT h2 That is, when the motor torque of the first steering motor 33 is set to T SM1 , the motor torque of the second steering motor 34 is set to T SM2 When T SM1 =T SM2 =(SAT h1 +SAT h2 ) / 2. When the first automatic return torque estimation value SAT is h1 and the second self-aligning torque estimation value SAT h2 Corrected to the first self-aligning torque estimation value SAT h1 The second self-aligning torque estimated value SAT h2 The correction interference torque required to obtain half of the total torque is T m1 When (SAT h1 +SAT h2 ) / 2=SAT h1 -T m1 =SAT h2 +T m1 Therefore, T m1 =(SAT h1 -SAT h2 ) / 2. The compensation torque calculation unit 56c calculates the correction interference torque T according to this relational expression. m1 By subtracting the correction interference torque T from the motor torque of the first steering motor 33 m1 , and the interference torque T m1 By adding the torque to the motor torque of the second steering motor 34 , it is possible to eliminate the deviation between the motor torque of the first steering motor 33 and the motor torque of the second steering motor 34 .

[0090] The frequency region setting unit 56d sets a frequency region in which the first steering motor 33 and the second steering motor 34 are cooperatively controlled. The frequency region setting unit 56d calculates the correction interference torque T output from the compensation torque calculation unit 56c. m1 Converted to correction interference torque T m2, and outputs it to the first steering control unit 53. In this embodiment, the frequency region setting unit 56d is a low-pass filter. The correction interference torque T output from the frequency region setting unit 56d m2 It is represented by the following formula (7).

[0091]

[0092] Among them, T m1 (s) is the Laplace transformed corrected interference torque T m1 , T m2 (s) is the Laplace transformed corrected interference torque T m2 ω1 is the cutoff frequency of the frequency region setting unit 56d which is a low-pass filter.

[0093] The frequency region setting unit 56d indicates Fig.10 The characteristics of the low pass filter are shown. Fig.10 In FIG. 5 , the vertical axis represents the gain [dB] in the frequency region setting unit 56 d, and the horizontal axis represents the steering frequency f [Hz]. The steering frequency f is the steering angle θ that changes when the steering wheel 11 is steered. h The frequency of Fig.10 As shown, the cut-off frequency ω1 is higher than the mechanical resonance frequency ω in the steering device 100. r Low. Resonance frequency ω r For example, it is about 10 Hz or more and about 50 Hz or less. The cut-off frequency ω1 is, for example, about 1 Hz or more and about 5 Hz or less. In the region where the steering frequency f is below the cut-off frequency ω1, the gain in the frequency region setting unit 56d is 0 dB, that is, the gain in the transfer function of the frequency region setting unit 56d is approximately 1. Therefore, in the region below the cut-off frequency ω1, T m2 =T m1 In the region where the steering frequency f is higher than the cut-off frequency ω1, the gain in the frequency region setting unit 56d is less than 1, T m2 <T m1 In the region where the steering frequency f is higher than the cut-off frequency ω1, the higher the steering frequency f, the smaller the gain. Therefore, as the steering frequency f increases, the correction interference torque T output from the coordination control unit 56a to the first steering control unit 53 increases. m2 The smaller.

[0094] As described above, the cooperative control unit 56a controls the first self-aligning torque estimation value SAT which is a value output from the first model following control unit 63 described later. h1 and a second self-aligning torque estimation value SAT which is a value output from a second model following control unit 68 described later. h2 The correction interference torque T is generated m2In the present embodiment, the cooperative control unit 56a generates the first self-aligning torque estimated value SAT h1 The second self-aligning torque estimated value SAT h2 The correction interference torque T m1 The value after low-pass filtering is taken as the correction interference torque T m2 . The first automatic return torque estimated value SAT h1 Equivalent to the "first estimated value". Second self-aligning torque estimated value SAT h2 Equivalent to the "second estimated value".

[0095] The cooperative control unit 56b generates the correction interference torque T in the same manner as the cooperative control unit 56a. m2 The correction interference torque T output from the coordination control unit 56b m2 The value of the correction interference torque T output from the coordination control unit 56a m2 In the following description, the correction interference torque T output from the coordination control unit 56a may be m2 It is called the correction interference torque T m2R The correction interference torque T output from the coordination control unit 56b m2 It is called the correction interference torque T m2L .

[0096] (Steering reaction force control unit)

[0097] The steering reaction force control units 57a and 57b control the steering reaction force transmitted to the steersman via the steering wheel 11. Figure 5 As shown in FIG. 1 , the steering reaction force control units 57a and 57b are input with the steering angle θ h . The steering reaction force control unit 57a controls the first steering side motor 31. The steering reaction force control unit 57b controls the second steering side motor 32. The steering reaction force control unit 57a sends a value of half of the desired steering reaction force as a command value to the first steering side motor 31 to control the first steering side motor 31. The steering reaction force control unit 57b sends a value of half of the desired steering reaction force as a command value to the second steering side motor 32 to control the second steering side motor 32. The first steering side motor 31 and the second steering side motor 32 are controlled by each steering reaction force control unit 57a, 57b respectively, and the output shaft 13 is rotated by the two steering side motors, thereby the steering reaction force applied to the steersman via the steering wheel 11, that is, the steering torque T hThe steering reaction force control unit 57a and the steering reaction force control unit 57b have the same structure except that the steering side motors to be controlled are different. Therefore, in the following description, the steering reaction force control unit 57a and 57b are used as representatives to describe the steering reaction force control unit 57a, and the description of the same structure in the steering reaction force control unit 57b as the steering reaction force control unit 57a is sometimes omitted.

[0098] like Fig.11 As shown, the steering reaction force control unit 57a includes a steering reaction force setting unit 70, an angle control unit 71, a state feedback unit 72, a third model tracking control unit 73, a torque conversion unit 74, subtractors SU6, SU7, SU8, SU9 and an adder AD4.

[0099] The steering reaction force setting unit 70 sets a target steering reaction force. The steering reaction force setting unit 70 receives as input the steering angle θ h and the automatic return torque estimation value SAT h . Automatic return torque estimation value SAT h The first automatic return torque estimation value SAT is h1 The second self-aligning torque estimated value SAT h2 The values ​​are calculated by addition in the adder AD4 and input to the steering reaction force setting unit 70 .

[0100] The steering reaction force setting unit 70 includes a low-pass filter 70a. The low-pass filter 70a filters the self-aligning torque estimation value SAT input to the steering reaction force setting unit 70. h At least a part of the frequency component higher than the predetermined cut-off frequency is removed. The predetermined cut-off frequency is, for example, about 10 Hz. The frequency of the self-aligning torque SAT is about 10 Hz or less. Therefore, at least a part of the frequency component higher than 10 Hz is removed from the self-aligning torque estimated value SAT by using the low-pass filter 70a. h Removing it can further improve the self-aligning torque estimation value SAT h The automatic return torque estimation value SAT input to the steering reaction force setting unit 70 is h The included frequency components higher than 10 Hz include, for example, components caused by the reaction force of the vehicle movement. In the present embodiment, the steering reaction force setting unit 70 uses the low-pass filter 70a to distinguish the reaction force of the vehicle movement and the tire contact information, that is, the self-aligning torque SAT, in the frequency region, and uses the more accurate self-aligning torque estimated value SAT. h To set the target steering reaction force.

[0101] In the present embodiment, the output angle θ of the output shaft 13 is adjusted by the first steering motor 31 and the second steering motor 32. s , thereby adjusting the difference in rotation angle between the input shaft 12 and the output shaft 13 connected by the torsion bar 14 to control the steering reaction force, that is, the steering torque T h Therefore, the steering reaction force setting unit 70 calculates the steering torque T h The output angle θ of the output shaft 13 required to achieve the target value s Here, the steering torque T h It is represented by the following formula (8).

[0102] T h =K t (θ h -θ s )···(8)

[0103] Among them, K t is the spring constant of the torsion bar 14 .

[0104] When the steering torque T h The target value is set to T hr , the output angle θ s The target value is set to θ sr When , according to the above formula (8), the output angle target value θ sr It is represented by the following formula (9).

[0105]

[0106] Here, the steering torque T h The relationship with the automatic return torque SAT is as follows: Fig. 12A As shown in the graph. Fig. 12A In the figure, the horizontal axis represents the self-aligning torque SAT, and the vertical axis represents the steering torque T h For example, in an electric power steering device in which the steering mechanism and the steering mechanism are mechanically connected, the steering torque T h The assist torque T output from the electric power steering device as The added value is considered to be substantially equal to the self-aligning torque SAT. as and steering torque T h For example, the relationship Fig. 12B As shown in the graph. Fig. 12B In the figure, the horizontal axis represents the steering torque T h , the vertical axis represents the assist torque T as According to SAT≈T h +T as relationship, yes Fig. 12B The assist torque Tas The curve plus the steering torque T h The resulting curve is Fig. 12B The curve of the self-aligning torque SAT is shown by the dashed line in FIG. Fig. 12A The self-aligning torque SAT and the steering torque T shown h A curve graph of the relationship.

[0107] The steering reaction force setting unit 70 is based on Fig. 12A The relationship shown in the curve diagram is calculated with the input self-aligning torque estimation value SAT h The value of the steering torque T h The value of steering torque target value T hr The steering reaction force setting unit 70 calculates the steering torque target value T hr and the input steering angle θ h Substitute into the above formula (9) to calculate the output angle target value θ sr .like Fig.11 As shown, the output angle target value θ sr is input to the subtractor SU9. The subtractor SU9 outputs the target angle value θ sr Subtract the current output angle θ s value and output it to the angle control unit 71.

[0108] The angle control unit 71 performs PD control to output the output angle target value θ input from the subtractor SU9. sr With the output angle θ s The difference between the values ​​of r3 The third controlled object 75 is a controlled object including the first steering motor 31. The transfer function P of the third controlled object 75 is m3 (s) is represented by, for example, the following formula (10).

[0109]

[0110] Where s is the Laplace transform, J m3 is a parameter corresponding to the inertia moment of the first steering motor 31, and B m3 This is a parameter corresponding to the viscous friction coefficient of the first steering motor 31 .

[0111] The PD gain in the angle control unit 71 is adjusted so that the value of the torque output from the angle control unit 71 is the steering torque target value T hr That is, the third input torque T output from the angle control unit 71 is half the value of r3 With T hr / 2 is equal. The third input torque T outputted from the angle control unit 71r3 is input to the subtractor SU7. The subtractor SU7 obtains the third input torque T r3 The third correction torque T outputted from the third model following control unit 73 is subtracted. f3 In addition, the subtractor SU7 calculates the third input torque T r3 Add the current steering torque T h half of the value, that is, T h / 2. By multiplying the value output from the subtractor SU6 by the gain K of the torque conversion unit 74 t / 2 to calculate T h The subtractor SU6 receives the steering angle θ as input. h Subtractor SU6 is used to calculate the steering angle θ h Subtract the output angle θ s , and outputs it to the torque conversion unit 74. Thus, the steering torque T can be calculated according to the relationship of the above formula (8). h half of the value, that is, T h / 2.

[0112] The force generated by the twisting of the torsion bar 14 is applied to the first steering motor 31 and the second steering motor 32 in a distributed manner as a reaction force. The torsion bar 14 applies a steering torque T to the first steering motor 31 and the second steering motor 32, respectively. h half of the torque. Therefore, as mentioned above, by changing T h / 2 and the third input torque T r3 By adding these, the reaction force received by the first steering motor 31 from the torsion bar 14 can be compensated.

[0113] The output from the subtractor SU7 is input to the adder AD5 and the third model following control unit 73. The adder AD5 outputs to the third controlled object 75 a value obtained by adding the output from the state feedback unit 72 and the output from the subtractor SU7.

[0114] In the present embodiment, the third model following control unit 73 is a model following controller configured to perform model following control. The third model following control unit 73 generates a third input torque T according to the output of the third controlled object 75 and the third nominal model NM3. r3 The third correction torque T f3 In this embodiment, the third correction torque T f3 is fed back to the third input torque T r3 The third nominal model NM3 is an internal model used as a model constraining the third controlled object 75 when controlling the third controlled object 75 .

[0115] In this embodiment, the third model tracking control unit 73 outputs the angle θs The third correction torque T is generated f3 , and fed back to the third input torque T r3 The third model tracking control unit 73 includes a third inverse nominal model 73a, a filter 73b, and a subtractor SU8.

[0116] The third model tracking control unit 73 is configured such that, when the transfer function of the filter 73b is Q3(s), in a frequency band where the gain in the gain characteristic of Q3(s) is substantially 1, the transfer function P of the third controlled object 75 is m3 (s) is constrained to be the transfer function P of the third nominal model NM3 nc (s). In the present embodiment, Q3(s) is equal to the complementary sensitivity function T3(s) of the inner loop formed by the third model tracking control unit 73. Q3(s), i.e., the complementary sensitivity function T3(s), has a gain of approximately 0 dB in the frequency band passed by the filter 73b, i.e., the gain in the transfer function is approximately 1.

[0117] In addition, in this specification, "the transfer function of the controlled object is constrained to be the transfer function of the nominal model" means that, for example, when observing the input-output relationship, the controlled object is controlled so that the transfer function of the controlled object appears to be the transfer function of the nominal model. In addition, in this specification, regarding "the gain is approximately 1", in addition to the case where the gain is 1, for example, it also includes the case where the gain is greater than 0.8 and less than 1.2. This numerical range is, for example, in the case where the reduction mechanism connected to each motor has a worm gear, and on the basis of considering the positive efficiency and reverse efficiency of the worm gear, the gain of the actual interference suppression characteristic can be adjusted to a range of 1. Since the efficiency of the worm gear is about 0.8, the gain needs to be adjusted by ±0.2 relative to the target value 1.

[0118] The third inverse nominal model 73a is an inverse model of the third nominal model NM3 for constraining the third controlled object 75. The transfer function P of the third nominal model NM3 is nc (s) is represented by the following equation (11), for example. The transfer function P of the third inverse nominal model 73a nc -1 (s) is represented by the following formula (12).

[0119]

[0120] Where s is the Laplace transform, J m3 is a parameter corresponding to the inertia moment of the first steering motor 31, and B m3 is a parameter corresponding to the viscous friction coefficient of the first steering motor 31, J h is a parameter equivalent to the inertia moment of the steering wheel 11, B his a parameter equivalent to the viscous friction coefficient of the steering wheel 11, K t is a spring constant of the torsion bar 14 , and G3 is a parameter corresponding to a gear ratio from the first steering motor 31 to the steering wheel 11 .

[0121] The output of the third controlled object 75 is input to the third inverse nominal model 73a. Specifically, the output angle θ is input to the third inverse nominal model 73a. s The third inverse nominal model 73a is based on the above equation (12) and the input output angle θ s The output torque T p3 When the output value of the third nominal model NM3 becomes the same as the output value of the third controlled object 75, the torque T p3 It is equal to the value of the torque input to the third nominal model NM3.

[0122] The subtractor SU8 subtracts the output of the subtractor SU7 from the output of the third inverse nominal model 73a to generate a differential torque T a3 The differential torque T output from the subtractor SU8 a3 The output value of the filter 73b is filtered by the filter 73b and input to the gain adjuster 73c. ​​The gain adjuster 73c multiplies the output value from the filter 73b by the feedback gain K to calculate the third correction torque T f3 , and the third correction torque T f3 Output to subtractor SU7.

[0123] The state feedback unit 72 generates the third input torque T according to the output of the third controlled object 75. r3 Feedback state compensation value V s3 , so that the apparent transfer function of the third controlled object 75 is close to the transfer function P of the third nominal model NM3 nc (s). The apparent transfer function of the third controlled object 75 is, for example, a transfer function of a portion located inside the feedback loop created by the third model tracking control unit 73 when the portion is regarded as a single portion. Specifically, in the present embodiment, the apparent transfer function of the third controlled object 75 refers to a transfer function of the entire portion from the subtractor SU7 to the output of the third controlled object 75, and is a transfer function of the portion that combines the state feedback unit 72 and the third controlled object 75. In the present embodiment, the state feedback unit 72 is responsive to the third correction torque T f3 The third input torque T after correction and before input to the third controlled object 75 r3 Feedback state compensation value V s3 .

[0124] State compensation value V s3The state compensation value V includes a compensation value for compensating at least a part of the inertial force generated by the third controlled object 75, the viscosity force generated by the third controlled object 75, and the friction force generated by the third controlled object 75. More specifically, the state compensation value V s3 The state compensation value V includes a compensation value for compensating at least a part of the inertial force generated by the first steering motor 31, the viscous force generated by the first steering motor 31, and the friction force generated by the first steering motor 31. s3 The compensation values ​​include the inertial force generated by the first steering motor 31 , the viscous force generated by the first steering motor 31 , and the friction force generated by the first steering motor 31 .

[0125] The state feedback unit 72 includes an inertia compensator 72a, a viscosity compensator 72b, and a friction compensator 72c. The inertia compensator 72a is configured to adjust the output angle θ of the output shaft 13 rotated by the first steering motor 31. s , calculates a compensation value for compensating at least a part of the inertial force generated by the first steering motor 31. The viscosity compensator 72b is adjusted according to the output angle θ s , calculates a compensation value for compensating at least a part of the viscosity force generated by the first steering motor 31. The friction compensator 72c is configured according to the output angle θ s , calculates a compensation value for compensating at least a portion of the friction force generated by the first steering motor 31. In this embodiment, the state compensation value V s3 The compensation value calculated by the inertia compensator 72a, the compensation value calculated by the viscosity compensator 72b, and the compensation value calculated by the friction compensator 72c are output to the adder AD5 and added to the third correction torque T f3 The corrected third input torque T r3 .

[0126] By adding the state compensation value V s3 The inertia, viscosity and friction in the steering system including the steering wheel 11 and the first steering motor 31 can be adjusted to desired values, and the steering reaction force received by the steerer from the steering wheel 11 can be adjusted to a value that facilitates steering. Therefore, the steering feeling felt by the steerer can be improved.

[0127] In addition, by providing the state feedback unit 72, the third controlled object 75 to be controlled by the feedback of the third model tracking control unit 73 can be made to be close to the third nominal model NM3 as an internal model. Therefore, when the model tracking control using the third model tracking control unit 73 is performed, the third controlled object 75 can be regarded as a model close to the third nominal model NM3, and the modeling error between the third controlled object 75 and the third nominal model NM3 can be reduced. Therefore, the gain in the gain characteristic of Q3(s) is made approximately 1, and the transfer function P of the third controlled object 75 can be expanded. m3 (s) is constrained to be the transfer function P of the third nominal model NM3 nc Therefore, the model following control by the third model following control unit 73 can be performed in a wider frequency band, and the steering feeling felt by the helmsman can be further improved.

[0128] In the present embodiment, the steering reaction force control unit 57a and the steering reaction force control unit 57b respectively control the third input torque T outputted from the angle control unit 71 to be equal to the third input torque T outputted from the angle control unit 71. r3 Set to T hr / 2, the output angle of the first steering motor 31 and the output angle of the second steering motor 32 are controlled by model following control, and the output angle θ of the output shaft 13 is set to s The control is performed so that the target steering torque T hr Thereby, the steering reaction force transmitted to the helmsman can be adjusted to an appropriate value.

[0129]

Rudder side control unit

[0130] The first steering control unit 53 generates a steering motor angle command value θ input from the first steering control unit 51. gra1 The second steering control unit 54 controls the first control object 65a including the first steering motor 33. The second steering control unit 54 controls the first control object 65a including the first steering motor 33 based on the steering motor angle command value θ input from the second steering control unit 52. gra2 The second control object 65b including the second steering motor 34 is controlled. In the following description, the first steering control unit 53 and the second steering control unit 54 are used as representatives, the first steering control unit 53 is described, and the description of the same structure of the second steering control unit 54 as the first steering control unit 53 is sometimes omitted.

[0131] like Figure 4AAs shown in FIG. 1 , the first steering control unit 53 includes a first processor 53a and a plurality of inverter circuits 58. The plurality of inverter circuits 58 independently supply power to the plurality of coil groups 37 in the first steering motor 33. Therefore, the redundancy of the first steering control unit 53 and the redundancy of the first steering motor 33 can be ensured. That is, even if any one of the plurality of inverter circuits 58 fails and cannot supply power to a certain coil group 37, power can be supplied to the other coil groups 37 through the other inverter circuits 58, and the first steering motor 33 can be appropriately driven.

[0132] In this embodiment, the inverter circuit 58 includes two inverter circuits, namely, a first inverter circuit 58a and a second inverter circuit 58b. The first inverter circuit 58a independently supplies power to the first coil group 37a in the first steering motor 33. The second inverter circuit 58b independently supplies power to the second coil group 37b in the first steering motor 33.

[0133] like Figure 4B As shown, the second steering control unit 54 includes a second processor 54a and a plurality of inverter circuits 59. The plurality of inverter circuits 59 independently supply power to the plurality of coil groups 37 in the second steering motor 34. Thus, the redundancy of the second steering control unit 54 and the redundancy of the second steering motor 34 can be ensured in the same manner as the first steering control unit 53 and the first steering motor 33. In the present embodiment, the inverter circuit 59 includes two, a first inverter circuit 59a and a second inverter circuit 59b. The first inverter circuit 59a independently supplies power to the first coil group 37a in the second steering motor 34. The second inverter circuit 59b independently supplies power to the second coil group 37b in the second steering motor 34.

[0134] The first processor 53a and the second processor 54a are semiconductor integrated circuits, also called central processing units (CPUs) or microprocessors. The first processor 53a and the second processor 54a sequentially execute computer programs stored in a ROM (not shown) and recording a command group for controlling motor driving, for example, to achieve desired processing.

[0135] like Figure 5 As shown, the first processor 53a receives the steering motor angle command value θ gra1 and correction interference torque T m2R .like Fig.13As shown in FIG. 1 , the first processor 53a includes an angle control unit 61, a state feedback unit 62, a first model tracking control unit 63, subtractors SU1, SU2, and adders AD1, AD2. That is, the first steering control unit 53 includes the angle control unit 61, the state feedback unit 62, the first model tracking control unit 63, subtractors SU1, SU2, and adders AD1, AD2. The steering motor angle command value θ input to the first processor 53a is gra1 is input to the subtractor SU1. The subtractor SU1 subtracts the steering motor angle command value θ from the steering motor angle command value θ. gra1 minus the first output angle θ of the first steering motor 33 g1 , and outputs it to the angle control unit 61. The angle control unit 61 calculates the first input torque T according to the value of the angle input from the subtractor SU1 by performing PD control. r1 , and output to subtractor SU2.

[0136] The subtractor SU2 is a subtractor of the first input torque T r1 The correction torque T outputted from the first model following control unit 63 is subtracted. f1 The output from the subtractor SU2 is input to the adder AD1 and the first model tracking control unit 63. The adder AD1 outputs the value obtained by adding the output from the state feedback unit 62 and the output from the subtractor SU2 to the adder AD2. The adder AD2 adds the disturbance torque T to the output from the adder AD1. d1 The obtained value is output to the first control object 65a. In the present embodiment, the first control object 65a includes the first steering motor 33, the first steering wheel 21, and the bushings 23d, 23e, 41a, and 42a provided in the steering mechanism 20. In the present embodiment, the first control object 65a includes the portion from the first steering motor 33 to the first steering wheel 21 in the vehicle. The output of the first control object 65a is the first output angle θ of the first steering motor 33. g1 .

[0137] like Fig.14 As shown in FIG. 1 , the first controlled object 65a can be represented by a simplified model in which the first steering motor 33 and the first steering wheel 21 are connected by an imaginary spring 20a. Fig.14 In the example, the spring constant K of the imaginary spring 20a is Bush1 It is a parameter corresponding to the equivalent spring constant of the elastic element including the bushings 23d, 23e, 41a, and 42a included in the first controlled object 65a. Spring constant K Bush1 It also includes the rigidity of the vehicle body. Fig.14 The θ shown Tire1 is the angle of the first steering wheel 21 .

[0138] In this embodiment, the first model following control unit 63 is a model following controller configured to perform model following control. Fig.13 As shown, the first model following control unit 63 generates a first input torque T t to be input to the first controlled object 65a based on the output of the first controlled object 65a and a first nominal model NM1 based on the structure of the first controlled object 65a. r1 Correction torque T for correction f1 In this embodiment, the correction torque T f1 is fed back to the first input torque T r1 The first nominal model NM1 is an internal model used as a model constraining the first controlled object 65a when controlling the first controlled object 65a.

[0139] In the present embodiment, the first model following control unit 63 controls the first steering motor 33 according to the first output angle θ g1 The correction torque T is generated f1 , and fed back to the first input torque T r1 The first model tracking control unit 63 includes a first inverse nominal model 63a, a filter 63b, a noise removal filter 63c, and subtractors SU3 and SU4.

[0140] The first model tracking control unit 63 is configured such that, when the transfer function of the filter 63b is Q1(s), in a frequency band where the gain in the gain characteristic of Q1(s) is substantially 1, the transfer function P of the first controlled object 65a is SAW1 (s) is constrained to be the transfer function P of the first nominal model NM1 na (s) In the present embodiment, Q1(s) is equal to the complementary sensitivity function T1(s) of the inner loop formed by the first model following control unit 63 .

[0141] The first inverse nominal model 63a is an inverse model of the first nominal model NM1 for constraining the first controlled object 65a. In this embodiment, the transfer function P of the first nominal model NM1 is na (s) is expressed by the following equation (13). The transfer function P of the first inverse nominal model 63a na -1 (s) is represented by the following formula (14).

[0142]

[0143] Where s is the Laplace transform, J m1 is a parameter corresponding to the inertia moment of the first steering motor 33, B m1 is a parameter corresponding to the viscous friction coefficient of the first steering motor 33, J Tyre1is a parameter corresponding to the inertia moment of the first steering wheel 21, B Tyre1 is a parameter corresponding to the viscous friction coefficient of the first steering wheel 21, K Bush1 is a parameter corresponding to the equivalent spring constant of the elastic element including the bushings 23d, 23e, 41a, and 42a in the first controlled object 65a, and G1 is a parameter corresponding to the gear ratio from the first steering motor 33 to the first steering wheel 21. Tyre1 The viscous elements of each bushing 23d, 23e, 41a, 42a are also included.

[0144] As shown in the above equation (13), the transfer function P of the first nominal model NM1 is na (s) contains at least the function F na (s). In this embodiment, the transfer function P na (s) is determined only by the function F na (s) composition.

[0145] according to Fig.14 The simplified first control object 65a shown in FIG. derives a first nominal model NM1. Fig.14 In order to obtain the self-aligning torque SAT1 generated by the first steering wheel 21, the model shown in FIG. 1 needs to obtain the first output angle θ from the output torque of the first steering motor 33 excluding the self-aligning torque SAT1 to the first output angle θ of the first steering motor 33 based on the simplified steering system characteristics. g1 In addition to improving the estimation accuracy of the self-aligning torque SAT1, it is also possible to design the steering characteristics that compensate for the compliance of the vehicle. Fig.14 The output torque T from the first steering motor 33 is obtained by using the simplified model shown in FIG. g1 The first output angle θ of the first steering motor 33 g1 The transfer characteristic becomes the following formula (15).

[0146]

[0147] D3=K Bush1 B Tyre1 +G1K Bush1 B m1

[0148] Here, the gear ratio from the first steering motor 33 to the first steering wheel 21 is about 300, so K can be Bush1 / G1 2 Taking advantage of this fact, by rearranging the right-hand side of the above equation (15), the transfer function P of the first nominal model NM1 can be derived: na (s).

[0149] The transfer function P of the first nominal model NM1 na The first term of (s), namely 1 / (J n1 s 2 +B n1 s) is a term related to the mechanical characteristics of the first steering motor 33. The transfer function P na The first term of (s) affects the responsiveness of the first steering motor 33. In the case of active front steering control, for example, the time constant is 0.05 seconds, so one tenth of the time constant is required as the responsiveness of the control. In order to achieve this responsiveness, it is preferable to compensate for the inertia of the first steering motor 33 and the friction of the first steering motor 33, so that the mechanical responsiveness of the first steering motor 33 is high. This can be achieved by providing a state feedback unit 62. In addition, the transfer function P na J in the first term of (s) n1 and B n1 is a parameter for setting the motor characteristic of the first steering motor 33 as viewed from the first model following control unit 63 after compensation by providing the state feedback unit 62. n1 and B n1 , it is possible to improve the robust stability of the first model following control unit 63. Thus, it is possible to achieve both responsiveness and robust stability.

[0150] In addition, the transfer function P of the first nominal model NM1 is na The second term of (s), namely (s 2 +α b1 s+α k1 ) / (s 2 +β b1 s+β k1 ) is a term related to the compensation of the flexible steering. The flexible steering is a term that occurs when an external force acts on the ground contacting part of the tire of the vehicle, and the suspension elements of the vehicle such as the rubber bushing are bent. Due to this bending, the tire produces an angle similar to the turning of the steering wheel, which causes a change in the actual steering angle. The flexible steering in this embodiment is caused by the change in the angle of the first steering wheel 21 and the angle of the second steering wheel 22 due to the bending of the suspension elements such as the bushings 23d, 23e, 41a, 42a. The physical parameters that affect the flexible steering are the elastic elements of the bushings and the viscosity elements of the tires. In the transfer function P na (s) is K Bush1 and B Tire1 In the transfer function P na In the second term of (s), by replacing K Bush1 and B Tire1 Set as an ideal parameter and determine α b1 , α k1 , β b1 , β k1, the first nominal model NM1 can be made into a model having a desired compliance characteristic. By performing model following control using the first nominal model NM1 obtained in this way, the compliance steering characteristic of the vehicle can be appropriately compensated. Thus, for example, even if the first battery 85a and the second battery 85b are arranged at any position of the vehicle, the driving stability of the vehicle can be ensured.

[0151] In addition, K Bush1 In the transfer function P na (s) only affects the second term, and K Bush1 The natural vibration frequency of K is sufficiently higher than the frequency band of the self-aligning torque SAT1 generated by the first steering wheel 21. Bush1 It has almost no effect on the estimation of the self-aligning torque SAT1. Bush1 The natural vibration frequency of is, for example, about 20 Hz or more and 30 Hz or less. The frequency band of the self-aligning torque SAT1 is, for example, about 10 Hz or less.

[0152] like Fig.13 As shown in FIG. 1 , the first inverse nominal model 63 a receives the output of the first controlled object 65 a as input. Specifically, the first inverse nominal model 63 a receives the first output angle θ of the first steering motor 33 as input. g1 The first inverse nominal model 63a is based on the above equation (14) and the input first output angle θ g1 The output torque T p1 That is, the first model following control unit 63 calculates the torque T using the first nominal model NM1 based on the output of the first controlled object 65a. p1 Torque T p1 When the output value of the first nominal model NM1 becomes the same value as the output value of the first controlled object 65a, it becomes equal to the value of the torque input to the first nominal model NM1.

[0153] The subtractor SU3 subtracts the output of the subtractor SU2 from the output of the first inverse nominal model 63a to generate a differential torque T a1 That is, the subtractor SU3 subtracts the torque T p1 Subtract the correction torque T f1 After being fed back, the state compensation value V described later is fed back s1 The first input torque T r1 The differential torque T a1 . Differential torque T a1 For example, the disturbance torque T d1 The estimated value of includes the self-aligning torque SAT1 of the first steered wheel 21 and the second interference torque caused by the second steered motor 34 driving the steered mechanism 20. The second interference torque is applied to the first controlled object 65a.

[0154] The differential torque T output from the subtractor SU3 a1 The differential torque T is filtered by the filter 63b and input to the subtractor SU4. a1 It is called differential torque T a1f The filter 63b is, for example, a filter formed by coupling a low-pass filter and a high-pass filter in series. Thus, the differential torque T after filtering in the filter 63b is a1f The frequency component is higher than the first cutoff frequency Cf1 of the high-pass filter in the filter 63b and lower than the second cutoff frequency Cf2 of the low-pass filter in the filter 63b. a1f The friction force, the self-aligning torque SAT1 of the first steering wheel 21, the disturbance torque caused by the looseness of the first controlled object 65a, and the torque fluctuation generated by the first controlled object 65a are included.

[0155] The subtractor SU4 obtains the differential torque T from the output value of the filter 63b. a1f The correction interference torque T outputted from the coordination control unit 56a is subtracted. m2R As the correction torque T f1 , and the correction torque T f1 The correction torque T output from the subtractor SU4 is f1 The input fed back to the first controlled object 65a, that is, the first input torque T r1 .

[0156] Here, as described above, the correction interference torque T m2R The value of the interference torque T is calculated based on the correction torque T output from the compensation torque calculation unit 56c. m1 Therefore, according to the steering frequency f, the differential torque T is obtained in the subtractor SU4. a1f Subtract the corrected interference torque T m2R Specifically, in the region where the steering frequency f is equal to or lower than the cut-off frequency ω1, the gain in the transfer function of the frequency region setting unit 56d is 1, so the correction interference torque T m2R The value of the correction interference torque T m1 The value of is the same. Therefore, in the subtractor SU4, the differential torque T a1f The subtracted value is equal to the corrected interference torque T m1 In this case, the first model tracking control unit 63 corrects the interference torque T m2R Included in the correction torque T f1 In this embodiment, the interference torque T is corrected. m2R Included in the correction torque Tf1 The model following control performed in the above embodiment is called “coordinated control CT1”. Coordinated control CT1 is equivalent to “first control”.

[0157] On the other hand, in the region where the steering frequency f is higher than the cut-off frequency ω1, the gain in the transfer function of the frequency region setting unit 56d is less than 1, so the correction interference torque T m2R The value is less than the correction interference torque T m1 Therefore, compared with the case where the steering frequency f is below the cut-off frequency ω1, the differential torque T a1f Subtract the corrected interference torque T m2R If the steering frequency f is higher than a certain level in the region higher than the cut-off frequency ω1, the correction interference torque T m2R The frequency region setting unit 56d is sufficiently attenuated. In this case, the subtractor SU4 is used to obtain the differential torque T a1f The subtracted value is regarded as substantially zero. Thus, in the region where the steering frequency f is higher than the cut-off frequency ω1, the differential torque T a1f Subtract the corrected interference torque T m2R The value of is smaller than that of the above-mentioned cooperative control CT1. In other words, in the region where the steering frequency f is higher than the cut-off frequency ω1, the correction interference torque T m2R Correction torque T f1 The influence caused by the coordinated control CT1 is smaller. m2R Correction torque T f1 The model tracking control that has a smaller influence than the coordinated control CT1 is called "non-interference control CT2". The non-interference control CT2 is equivalent to the "second control". In addition, in this specification, "the influence of the correction interference torque applied to the correction torque is smaller than that of the coordinated control" includes the case where the correction interference torque is not input to each model tracking control unit.

[0158] Thus, in this embodiment, the first model tracking control unit 63 can perform the coordinated control CT1 and the non-interference control CT2. Fig.10 As shown in FIG. 1 , when the steering frequency f is in the coordinated control region PH1 below the cutoff frequency ω1, the coordinated control CT1 is executed, and when the steering frequency f is in the non-interference control region PH2 higher than the cutoff frequency ω1, the non-interference control CT2 is executed. That is, the coordinated control CT1 and the non-interference control CT2 are executed according to the steering angle θ that changes when the steering wheel 11 is steered. hThe steering frequency f when the non-interference control CT2 is executed is higher than the steering frequency f when the coordinated control CT1 is executed. In this embodiment, the coordinated control CT1 and the non-interference control CT2 are automatically switched according to the steering frequency f by the low-pass filter processing implemented in the frequency region setting unit 56d.

[0159] like Fig.13 As shown, the differential torque T output from the filter 63b a1f is input to the noise removal filter 63c. The noise removal filter 63c extracts the differential torque T a1f At least a part of the noise is removed. The torque output from the noise removal filter 63c is the first self-aligning torque estimation value SAT h1 . The first automatic return torque estimation value SAT h1 is the estimated value of the self-aligning torque SAT1 generated by the first steering wheel 21. Figure 5 As shown in FIG. 1 , the first self-aligning torque estimation value SAT output from the noise removal filter 63c is h1 The command value generating units 55a and 55b, the cooperative control units 56a and 56b, and the steering reaction force control units 57a and 57b in the first steering control unit 51 and the second steering control unit 52 are inputted.

[0160] like Fig.13 As shown, the state feedback unit 62 generates a first output angle θ according to the output of the first control object 65a, that is, the first output angle θ g1 , for the first input torque T r1 Feedback state compensation value V s1 , so that the apparent transfer function of the first controlled object 65a is close to the transfer function P of the first nominal model NM1 na (s). The apparent transfer function of the first controlled object 65a is, for example, a transfer function of a portion located inside the feedback loop created by the first model tracking control unit 63 when the portion is regarded as a single portion. Specifically, in the present embodiment, the apparent transfer function of the first controlled object 65a refers to a transfer function of the entire portion from the subtractor SU2 to the output of the first controlled object 65a, and is a transfer function of the portion that combines the state feedback unit 62 and the first controlled object 65a. In the present embodiment, the state feedback unit 62 is responsive to the correction torque T f1 The first input torque T after correction and before input to the first controlled object 65a r1 Feedback state compensation value V s1 .

[0161] State compensation value V s1The state compensation value V includes a compensation value for compensating at least a part of the inertial force generated by the first controlled object 65a, the viscosity force generated by the first controlled object 65a, and the friction force generated by the first controlled object 65a. More specifically, the state compensation value V s1 The state compensation value V includes a compensation value for compensating at least a part of the inertial force generated by the first steering motor 33, the viscosity force generated by the first steering motor 33, and the friction force generated by the first steering motor 33. s1 The compensation values ​​include the inertial force generated by the first steering motor 33 , the viscous force generated by the first steering motor 33 , and the friction force generated by the first steering motor 33 .

[0162] The state feedback unit 62 includes an inertia compensator 62a, a viscosity compensator 62b, and a friction compensator 62c. The inertia compensator 62a is configured to adjust the first output angle θ of the first steering motor 33. g1 The viscous compensator 62b calculates a compensation value for compensating at least a part of the inertial force generated by the first steering motor 33. g1 The compensation value for compensating at least a part of the viscosity force generated by the first steering motor 33 is calculated. The friction compensator 62c is adjusted according to the first output angle θ of the first steering motor 33. g1 The compensation value for compensating at least a part of the friction force generated by the first steering motor 33 is calculated. s1 The compensation value calculated by the inertia compensator 62a, the compensation value calculated by the viscosity compensator 62b, and the compensation value calculated by the friction compensator 62c are output to the adder AD1 and added to the correction torque T f1 The corrected first input torque T r1 Add.

[0163] Next, the control of the first model following control unit 63 will be described in further detail. The first model following control unit 63 controls the first controlled object 65a using a first inverse nominal model 63a which is an inverse model of the first nominal model NM1 included as an internal model.

[0164] The first model tracking control unit 63 is similar in structure to the existing disturbance inference device (disturbance observer), but the functions and effects pursued are different. The existing disturbance inference device infers the disturbance torque by setting the inverse plant model as an internal model to a model close to the first control object 65a, and reduces the influence of the disturbance by adding or subtracting the disturbance torque in advance.

[0165] The control of the first model following control unit 63 in this embodiment uses the transfer function P of the first controlled object 65a to be controlled by a feedback loop. SAW1 (s) The transfer function P of the first nominal model NM1 constrained as an internal model na For example, if the first nominal model NM1 is defined in such a way that there is no torque fluctuation, the transfer function P of the first controlled object 65a is set to SAW1 (s) is constrained to have a characteristic without torque fluctuation, and as a result, torque fluctuation can be reduced by applying compensation for torque fluctuation. In addition, by setting the first nominal model NM1 as a low inertia model and using the first nominal model NM1 to constrain the first control object 65a, the first control object 65a can be treated as a low inertia model. In addition, by setting the first nominal model NM1 as a low viscosity model and using the first nominal model NM1 to constrain the first control object 65a, the first control object 65a can also be treated as a low viscosity model. By performing model tracking control by the first model tracking control unit 63, in addition to compensating for the torque fluctuation of the first steering side motor 33, for example, loss torque compensation or motor inertia compensation is also performed. In the above equations (13) and (14), by appropriately setting J n1 and B n1 , the transfer function P of the first controlled object 65a can be SAW1 (s) imparts desired frequency characteristics.

[0166] When the transfer function P of the first controlled object 65a is SAW1 (s) and the transfer function P of the first nominal model NM1 na When the modeling error of (s) is Δ(s), the transfer function P of the first controlled object 65a is SAW1 (s) is represented by the following formula (16).

[0167]

[0168] Transfer function P of the first controlled object 65a SAW1 The gain characteristic of (s) has peaks at two frequency values, for example. The modeling error Δ(s) appears, for example, near the peak with a higher frequency among the two peaks in the gain characteristic of the first controlled object 65a. Fig.15 As shown in FIG. 1 , the inverse of the modeling error Δ(s) 1 / Δ(s) has a valley in a relatively high-frequency region. Fig.15 In the example, the modeling error Δ(s) is expressed as an absolute value. When the modeling error Δ(s) increases, the transfer function P of the first controlled object 65a becomes SAW1 (s) and the transfer function P of the first nominal model NM1 na(s) becomes larger, and the control of the first controlled object 65a using the first nominal model NM1 by the first model tracking control unit 63 becomes unstable. Therefore, in the region where the modeling error Δ(s) is relatively small, the gain of the complementary sensitivity function T1(s), i.e., Q1(s), is set to approximately 1, and the first controlled object 65a is constrained to the first nominal model NM1, thereby enabling the first controlled object 65a to be stably and appropriately controlled. The transfer function P of the first nominal model NM1 can be adjusted to na J in (s) n1 and B n1 The frequency characteristics of the modeling error Δ(s) are adjusted. The frequency band in which the gain of Q1(s) is approximately 1 can be adjusted by adjusting the first cutoff frequency Cf1 and the second cutoff frequency Cf2. Thus, in the frequency band in which the modeling error Δ(s) is small, the gain of Q1(s) can be adjusted to approximately 1. In this embodiment, the complementary sensitivity function T1(s), that is, the gain of Q1(s), is set within a range of 0.8 or more and less than 1.

[0169] exist Fig.15 In the above example, 1 / Δ(s) is relatively high in the frequency band below the second cutoff frequency Cf2, and decreases sharply in the frequency band higher than the second cutoff frequency Cf2. The model following control that constrains the first controlled object 65a to the first nominal model NM1 can be stably performed in the range where 1 / Δ(s) is greater than 1, that is, greater than 0 dB. Therefore, Fig.15 As shown, by adjusting 1 / Δ(s) to be greater than 1 in the frequency band where the gain of Q1(s) is approximately 1, the first controlled object 65a can be constrained to the first nominal model NM1 and stably and appropriately controlled when the gain of Q1(s) is approximately 1.

[0170] For example, in order to expand the frequency band in which the first controlled object 65a can be constrained to the first nominal model NM1 and stably and appropriately controlled, as long as 1 / Δ(s) is not less than 1, that is, Fig.15 In the frequency band where the curve representing 1 / Δ(s) intersects with the horizontal axis, the second cut-off frequency Cf2 can be increased. However, when the second cut-off frequency Cf2 is too high, in the frequency band higher than the second cut-off frequency Cf2, although 1 / Δ(s) becomes lower, the gain of Q1(s) is still relatively high, and the control may become unstable. In contrast, for example, by making the number of low-pass filters in the filter 63b more than 3 times, the gain of Q1(s) can be sharply reduced in the region where the frequency is higher than the second cut-off frequency Cf2. Thus, even if the second cut-off frequency Cf2 is relatively high, the gain of Q1(s) can be immediately reduced in the frequency band higher than the second cut-off frequency Cf2, so that the control of the first control object 65a can be suppressed from becoming unstable.

[0171] The robust stability of the first model tracking control unit 63 is ensured when the small gain theorem expressed by the following equation (17) holds true between the complementary sensitivity function T1(s) and the modeling error Δ(s).

[0172]

[0173] In order to satisfy the above formula (17), the first nominal model NM1 needs to be set in such a way that the modeling error Δ(s) is minimized within the frequency band of the model following control. For example, when the responsiveness to be achieved is a time constant of 0.05 seconds, the first nominal model NM1 needs to be set in such a way that the modeling error Δ(s) is minimized to 40 Hz, which is 10 times the frequency. In this embodiment, for example, Fig.14 As shown, by capturing the first controlled object 65a with a simplified model and setting the first nominal model NM1, it is possible to set the first nominal model NM1 such that the modeling error Δ(s) is reduced to 40 Hz.

[0174] Considering Fig.14 The output torque T from the first steering motor 33 in the simplified model shown is g1 The first output angle θ of the first steering motor 33 g1 The transfer characteristic of the filter 63b, i.e., the modeling error not included in the above-mentioned formula (15), the transfer function Q1(s) of the filter 63b is designed to satisfy the above-mentioned formula (17). In this embodiment, by providing the state feedback unit 62, the influence of the changes in various parameters of the first control object 65a on the formula (17) can be compensated. In addition, in this embodiment, an example of installing the state feedback unit 62 by the transfer function is shown, but the state feedback unit 62 can also be installed by an extended state space representation that uses the disturbance as a part of the state variable.

[0175] like Figure 5 As shown, the steering motor angle command value θ is input to the second processor 54a. gra2 and correction interference torque T m2L .like Fig.16 As shown in FIG. 1 , the second processor 54a includes an angle control unit 66, a state feedback unit 67, a second model tracking control unit 68, subtractors SU10, SU11, and adders AD6, AD7. That is, the second steering control unit 54 includes the angle control unit 66, the state feedback unit 67, the second model tracking control unit 68, subtractors SU10, SU11, and adders AD6, AD7. The steering motor angle command value θ input to the second processor 54a is gra2 The subtractor SU10 is inputted to the subtractor SU10. The subtractor SU10 is inputted to the subtractor SU10 from the steering motor angle command value θ gra2minus the second output angle θ of the second steering motor 34 g2 , and outputs it to the angle control unit 66. The angle control unit 66 calculates the second input torque T according to the value of the angle input from the subtractor SU10 by performing PD control. r2 , and output to subtractor SU11.

[0176] The subtractor SU11 obtains the second input torque T r2 The correction torque T outputted from the second model following control unit 68 is subtracted. f2 The output from the subtractor SU11 is input to the adder AD6 and the second model tracking control unit 68. The adder AD6 outputs the value obtained by adding the output from the state feedback unit 67 and the output from the subtractor SU11 to the adder AD7. The adder AD7 adds the disturbance torque T to the output from the adder AD6. d2 The obtained value is output to the second control object 65b. In this embodiment, the second control object 65b includes the second steering motor 34, the second steering wheel 22, and Figure 2 The bushings 23d, 23e, 41a, and 42a shown are similarly provided around the second steering wheel 22 and the second steering motor 34. In the present embodiment, the second control object 65b includes the portion of the vehicle from the second steering motor 34 to the second steering wheel 22. The output of the second control object 65b is the second output angle θ of the second steering motor 34. g2 The second control object 65b can be controlled by Fig.14 The transfer function P of the second controlled object 65b is represented by a simplified model as shown in FIG. SAW2 (s) is expressed in the same manner as the first controlled object 65a.

[0177] The second model following control unit 68 performs model following control on the second controlled object 65b in the same manner as the first model following control unit 63. The second model following control unit 68 generates a second input torque T t to be input to the second controlled object 65b based on the output of the second controlled object 65b and a second nominal model NM2 based on the structure of the second controlled object 65b. r2 Correction torque T for correction f2 In this embodiment, the correction torque T f2 is fed back to the second input torque T r2 The second nominal model NM2 is an internal model used as a model for constraining the second controlled object 65b when controlling the second controlled object 65b. The second model tracking control unit 68 is based on the second output angle θ of the second steering motor 34. g2 The correction torque T is generated f2 , and fed back to the second input torque Tr2 The second model tracking control unit 68 includes a second inverse nominal model 68a, a filter 68b, a noise removal filter 68c, a subtractor SU12, and an adder AD8. The filter 68b is the same as the filter 63b. The noise removal filter 68c is the same as the noise removal filter 63c.

[0178] The second inverse nominal model 68a is an inverse model of the second nominal model NM2 for constraining the second controlled object 65b. In this embodiment, the transfer function P of the second nominal model NM2 is nb (s) is expressed by the following equation (18). The transfer function P of the second inverse nominal model 68a nb -1 (s) is represented by the following formula (19).

[0179]

[0180] Where s is the Laplace transform, J m2 is a parameter corresponding to the inertia moment of the second steering motor 34, and B m2 is a parameter corresponding to the viscous friction coefficient of the second steering motor 34, J Tyre2 is a parameter corresponding to the inertia moment of the second steering wheel 22, B Tyre2 is a parameter corresponding to the viscous friction coefficient of the second steering wheel 22, K Bush2 G2 is a parameter corresponding to the equivalent spring constant of the elastic element including the bushing in the second controlled object 65 b , and G3 is a parameter corresponding to the gear ratio from the second steered side motor 34 to the second steered wheel 22 .

[0181] As shown in the above equation (18), the transfer function P of the second nominal model NM2 is nb (s) contains at least the function F nb (s). In this embodiment, the transfer function P nb (s) is determined only by the function F nb (s) composition.

[0182] like Fig.16 As shown in FIG. 1 , the second inverse nominal model 68 a is input with the output of the second controlled object 65 b. Specifically, the second inverse nominal model 68 a is input with the second output angle θ of the second steering motor 34. g2 The second inverse nominal model 68a is based on the above equation (19) and the input second output angle θ g2 The output torque T p2 That is, the second model following control unit 68 calculates the torque T according to the output of the second controlled object 65b using the second nominal model NM2. p2 Torque T p2When the output value of the second nominal model NM2 becomes the same value as the output value of the second controlled object 65 b , it becomes equal to the value of the torque input to the second nominal model NM2 .

[0183] The subtractor SU12 subtracts the output of the subtractor SU11 from the output of the second inverse nominal model 68a to generate a differential torque T a2 That is, the subtractor SU12 subtracts the torque T p2 Subtract the feedback correction torque T f2 Then the state compensation value V described later is fed back s2 The second input torque T r2 The differential torque T a2 . Differential torque T a2 For example, the disturbance torque T d2 The estimated value of includes the self-aligning torque of the second steered wheel 22 and the first interference torque caused by the first steered motor 33 driving the steered mechanism 20. The first interference torque is applied to the second controlled object 65b.

[0184] The differential torque T output from the subtractor SU12 a2 The differential torque T is filtered by the filter 68b and input to the adder AD8. a2 It is called differential torque T a2f . Differential torque T a2f It includes friction force, the self-aligning torque of the second steering wheel 22, the disturbance torque caused by the looseness of the second controlled object 65b, and the torque fluctuation generated by the second controlled object 65b.

[0185] The adder AD8 adds the correction interference torque T output from the coordination control unit 56b. m2L The output value from the filter 68b, that is, the differential torque T a2f Added together as the correction torque T f2 , and the correction torque T f2 The correction torque T output from the adder AD8 is output to the subtractor SU11. f2 The input fed back to the second controlled object 65b, that is, the second input torque T r2 .

[0186] Here, the correction interference torque T m2L The correction interference torque T m2R Similarly, the value changes according to the steering frequency f. Thus, in the present embodiment, the second model following control unit 68 can execute the cooperative control CT1 and the non-interference control CT2 in the same manner as the first model following control unit 63 .

[0187] The noise removal filter 68c is input with the differential torque T output from the filter 68b. a2f The noise removal filter 68c extracts the differential torque T a2f At least a part of the noise is removed. The torque output from the noise removal filter 68c is the second self-aligning torque estimation value SAT h2 The second automatic return torque estimation value SAT h2 is the estimated value of the self-aligning torque generated by the second steering wheel 22. Figure 5 As shown in FIG. 1 , the second self-aligning torque estimation value SAT output from the noise removal filter 68c is h2 The command value generating units 55a and 55b, the cooperative control units 56a and 56b, and the steering reaction force control units 57a and 57b in the first steering control unit 51 and the second steering control unit 52 are inputted.

[0188] like Fig.16 As shown, the state feedback unit 67 generates a second output angle θ according to the output of the second control object 65b, that is, the second output angle θ g2 , so that the apparent transfer function of the second controlled object 65b is close to the transfer function P of the second nominal model NM2 nb (s) for the second input torque T r2 Feedback state compensation value V s2 The apparent transfer function of the second controlled object 65b is, for example, a transfer function of a portion located inside the feedback loop created by the second model tracking control unit 68 when the portion is regarded as a single portion. Specifically, in the present embodiment, the apparent transfer function of the second controlled object 65b refers to a transfer function of the entire portion from the subtractor SU11 to the output of the second controlled object 65b, and is a transfer function of the portion that combines the state feedback unit 67 and the second controlled object 65b. In the present embodiment, the state feedback unit 67 is used to correct the torque T f2 The second input torque T after correction and before input to the second controlled object 65b r2 Feedback state compensation value V s2 .

[0189] In this embodiment, the state feedback unit 67 includes an inertia compensator 67a, a viscosity compensator 67b, and a friction compensator 67c, similarly to the state feedback unit 62. s2 are compensation values ​​including the inertial force generated by the second steering motor 34, the viscous force generated by the second steering motor 34, and the friction force generated by the second steering motor 34. Each compensation value is output to the adder AD6 and is added to the correction torque T f2 The corrected second input torque T r2 Add.

[0190] In this embodiment, in order to meet the highest "D" standard of the automotive safety level (ASIL: Automotive Safety Integrity Level) defined in the international functional safety standard "ISO26262", that is, ASIL D, the following ASIL Decomposition is used. In the drive system for driving the steering mechanism 20, the first steering motor 33 and the second steering motor 34 are each a motor having two systems of coil groups 37, and the first steering control unit 53 and the second steering control unit 54 are provided with a plurality of inverter circuits 58 and 59 that independently supply power to each coil group 37 in each steering motor controlled by each steering control unit. As a result, the motor for driving the steering mechanism 20 and the inverter circuit for driving the motor each meet the standard of ASIL C. Therefore, by their combination, ASIL D=ASIL C(D)+ASIL C(D), and the drive system for driving the steering mechanism 20 meets the standard of ASIL D.

[0191] When the steering mechanism 20 is driven by the first steering motor 33 and the second steering motor 34 which are driven independently as described above, if there is a deviation between the driving of the first steering motor 33 and the driving of the second steering motor 34, the first interference torque caused by the first steering motor 33 driving the steering mechanism 20 is applied to the second control object 65b which is the control object of the second steering motor 34, and the second interference torque caused by the second steering motor 34 driving the steering mechanism 20 is applied to the first control object of the first steering motor 33. That is, the output torque of the first steering motor 33 and the output torque of the second steering motor 34 interfere with each other. Therefore, it is necessary to solve the problem of interference between the two steering motors while maintaining the independence of each steering motor and each inverter circuit 58, 59.

[0192] Generally speaking, as a method for solving the interference problem of the output of two motors as described above, there is a known method for achieving response synchronization of the speeds of the two motors. As a means for implementing this method, there are usually the following means: exchanging speed information between the two motors and controlling the correction of the speed of each motor. However, in order to meet the safety standard of the above-mentioned ASIL D, it is necessary to electrically maintain the independence of each motor and each inverter circuit. Therefore, for example, it is necessary to exchange speed information between the motors via a communication unit such as CAN. However, in this case, deviations and delays in communication timing occur, making it difficult to achieve speed synchronization between the motors. In addition, for example, a method is also considered in which, in addition to the two control units that control the two motors, a third control unit is provided to achieve speed synchronization between the two motors, but in this case, a third control unit needs to be provided, and accordingly, there are problems such as an increase in the number of components of the control device in the steering device or a complication of the control device.

[0193] In order to solve the above problem, in the present embodiment, the following method is adopted: the model following control is adopted in the torque control of the two steering motors to synchronize the speeds of the two steering motors. If the two steering motors are made to fall into the same nominal model, the torque commands are made the same, and thus the speed asynchronism of the steering motors can be compensated even when the loads applied to the steering motors are different.

[0194] Specifically, in the present embodiment, the first model following control unit 63 is configured to constrain the transfer function of the first controlled object 65a to the transfer function of the first nominal model NM1 in a frequency band where the gain is substantially 1 in the gain characteristic of the complementary sensitivity function T1(s) to the modeled error Δ(s) between the first controlled object 65a including the first steering motor 33 and the first nominal model NM1, that is, the transfer function Q1(s) of the filter 63b. The second model following control unit 68 is configured to constrain the transfer function of the second controlled object 65b to the transfer function of the second nominal model NM2 in a frequency band where the gain is substantially 1 in the gain characteristic of the complementary sensitivity function T2(s) to the modeled error Δ(s) between the second controlled object 65b including the second steering motor 34 and the second nominal model NM2, that is, the transfer function Q2(s) of the filter 68b. In this way, by constraining each of the control objects including each steering motor to the nominal model by model following control, the interference torque caused by the other steering motor can be compensated in the control of each steering motor. That is, the first steering control unit 53 compensates for the second interference torque caused by the second steering motor 34 driving the steering mechanism 20 by the model following control in which the transfer function of the first control object 65a is constrained to the transfer function of the first nominal model NM1 based on the structure of the first control object 65a. The second steering control unit 54 compensates for the first interference torque caused by the first steering motor 33 driving the steering mechanism 20 by the model following control in which the transfer function of the second control object 65b is constrained to the transfer function of the second nominal model NM2 based on the structure of the second control object 65b. Therefore, compared with the case of using a communication unit such as CAN, it is easy to appropriately synchronize the rotation speed of the first steering motor 33 and the rotation speed of the second steering motor 34, and the steering mechanism 20 can be appropriately controlled. Thus, the interference problem between the two steering motors can be solved while maintaining the electrical independence of each steering motor and each steering control unit. Therefore, the controllability of the steering device 100 can be improved while ensuring the safety of the steering device 100, thereby improving the steering performance of the steering device 100. In addition, since there is no need to provide the third control unit as described above, it is possible to suppress an increase in the number of components of the control device 50 in the steering device 100 and to suppress the complexity of the control device 50.

[0195] Furthermore, by performing model following control in the first model following control unit 63 and the second model following control unit 68, it is possible to compensate for torque fluctuations and friction of the first steering motor 33 and the second steering motor 34. Therefore, in an advanced driver-assistance system (ADAS) or automatic driving of a vehicle, it is possible to control the lateral movement of the vehicle with less force.

[0196] Sometimes, it is difficult to compensate for the asynchronism of the speeds of the steering motors due to the deviation between the torque constant of each steering motor and the detection value of the current sensor (not shown) that can detect the current supplied to each steering motor. In contrast, in the present embodiment, the gains of the complementary sensitivity functions T1(s) and T2(s), that is, Q1(s) and Q2(s), are set within a range of 0.8 or more and less than 1. By setting the gains of Q1(s) and Q2(s) to be slightly less than 1, the strength of the model following control performed in each model following control unit can be appropriately weakened. For example, if the gain is strictly set to 1 in one model following control unit to improve the disturbance suppression characteristic, the disturbance can be appropriately suppressed for the control object including the steering motor on one side, but due to the suppression of the disturbance, the disturbance applied to the control object including the steering motor on the other side that interferes with the steering motor on one side becomes larger. In contrast, by appropriately reducing the intensity of the model following control performed in each model following control unit as described above, it is possible to appropriately suppress the interference in each control object while reducing the influence of the suppression of the interference in each control object on the other control object as interference. Therefore, in each control object including each steering motor, the influence of the steering motors interfering with each other can be evenly shared and received. Thus, even if there is a deviation between the torque constant of each steering motor and the detection value of the current sensor (not shown), it is possible to easily compensate for the asynchronous speed of each steering motor.

[0197] In addition, according to the present embodiment, the transfer function P of the first nominal model NM1 is na (s) is the first output angle θ of the first steering motor 33. g1 With the first input torque T r1 The transfer function P of the second nominal model NM2 is equivalent to the target value of the mechanical compliance. nb (s) is the second output angle θ of the second steering motor 34. g2 With the second input torque T r2The transfer function is equivalent to the target value of the mechanical compliance of the ratio of the first control object 65a and the second control object 65b. That is, the model following control for controlling the first control object 65a including the first steering motor 33 and the model following control for controlling the second control object 65b including the second steering motor 34 are virtual compliance controls. Therefore, by constraining each control object to each nominal model, the mechanical compliance from the input to the output of each steering motor can be virtually replaced with the preferred mechanical compliance to control each control object. As a result, the flexible steering characteristics of the vehicle, the steering characteristics of the vehicle, and the body rigidity of the vehicle can be appropriately compensated. Therefore, the steering performance of the steering device 100 can be further improved. By being able to compensate for the influence of the body rigidity of the vehicle, there is no need to set additional reinforcement materials in the vehicle in order to improve the vehicle's motion performance. Therefore, the vehicle's motion performance can be improved while reducing the number of components of the vehicle. In addition, there is no need to set reinforcement materials, and the vehicle can be made lighter accordingly.

[0198] In addition, according to the present embodiment, the first control object 65a includes the first steering wheel 21. The second control object 65b includes the second steering wheel 22. Therefore, the above-mentioned virtual compliance control can also be performed by considering the inertia, viscosity, and rigidity of the first steering wheel 21 and the second steering wheel 22. Therefore, the flexible steering characteristics of the vehicle, the steering characteristics of the vehicle, and the body rigidity of the vehicle can be compensated more appropriately, thereby further improving the steering performance in the steering device 100.

[0199] In addition, according to the present embodiment, the first control object 65a and the second control object 65b each include at least one bushing 23d, 23e, 41a, 42a, etc. provided in the steering mechanism 20. Therefore, the above-mentioned virtual compliance control can also be performed in consideration of the rigidity and viscosity of each bushing. Therefore, the vehicle's flexible steering characteristics, the vehicle's steering characteristics, and the vehicle's body rigidity can be compensated more appropriately, thereby further improving the steering performance of the steering device 100.

[0200] In addition, according to the present embodiment, the transfer function P of the first nominal model NM1 is na (s) at least includes the function F represented by the above formula (13) na (s). Function F na (s) is based on Fig.14 The transfer function P of the first nominal model NM1 is obtained by simplifying the model from the first steering motor 33 to the first steering wheel 21. na (s) contains such a function F na (s), the first control object 65a can be constrained to a more appropriate model by model following control. Therefore, the steering performance of the steering device 100 can be further improved.na (s), the dynamic characteristics of the steering mechanism 20 can be made to enter the first nominal model NM1 for model following control. As a result, the action of the steering mechanism 20 when the steering wheel 11 is steered can be ideally corrected. Therefore, for example, even if there are uneven surfaces on the road surface where the vehicle is traveling, it is possible to prevent the steering wheel 11 from being removed.

[0201] In addition, according to the present embodiment, the transfer function P of the second nominal model NM2 is nb (s) at least includes the function F represented by the above formula (18) nb (s). Function F nb (s) is based on Fig.14 The transfer function P of the second nominal model NM2 is obtained by simplifying the model from the first steering motor 33 to the first steering wheel 21 and the simplified model from the second steering motor 34 to the second steering wheel 22. nb (s) contains such a function F nb (s), the second control object 65b can be constrained to a more appropriate model by model tracking control. Therefore, the steering performance of the steering device 100 can be further improved. nb (s), the dynamic characteristics of the steering mechanism 20 can be made to enter the second nominal model NM2 for model following control. As a result, the action of the steering mechanism 20 when steering the steering wheel 11 can be more ideally corrected. Therefore, for example, even if there are uneven surfaces on the road surface where the vehicle is traveling, it is possible to further suppress the steering wheel 11 from being removed.

[0202] According to the present embodiment, the first model following control unit 63 calculates the torque T using the first nominal model NM1 based on the output of the first controlled object 65a. p1 With the first input torque T r1 The first estimated value including the second interference torque, that is, the first self-aligning torque estimated value SAT is calculated by the difference between h1 The second model following control unit 68 calculates the torque T using the second nominal model NM2 based on the output of the second controlled object 65b. p2 With the second input torque T r2 The second estimated value including the first interference torque, that is, the second self-aligning torque estimated value SAT is calculated by the difference between h2 The steering reaction force control units 57a and 57b adjust the first self-aligning torque estimated value SAT according to the h1 The second self-aligning torque estimated value SAT h2 The sum of the values ​​is the estimated self-aligning torque SAT. h, to control the reaction force transmitted to the steersman. The first interference torque and the second interference torque have the same absolute value and opposite sign. Therefore, if the first automatic return torque estimation value SAT h1 The second self-aligning torque estimated value SAT h2 When the first interference torque and the second interference torque are added, the self-aligning torque estimation value SAT can be calculated. h As a value excluding the first interference torque and the second interference torque. Thus, the total self-aligning torque generated by the first steering wheel 21 and the second steering wheel 22 can be estimated with high accuracy. Therefore, the steering reaction force transmitted to the steersman, that is, the steering torque T h The steering feel of the helmsman can be improved by setting the steering wheel to an appropriate value.

[0203] In a steering device of a steer-by-wire method, it is necessary to avoid limiting the output of the motor due to the heat generated by the motor itself, i.e., self-heating. The cause of the self-heating of the motor is the resistance loss (ohmic loss) of the current flowing through the motor. The motor generates heat in proportion to the square of the current flowing through the motor. In order to suppress excessive self-heating of the motor, it is sufficient to suppress the absolute value of the maximum current flowing through the motor to a lower level. Therefore, in the present embodiment, in order to appropriately suppress the self-heating of the first steering side motor 33 and the self-heating of the second steering side motor 34, it is effective to equalize the current flowing in the two steering side motors and reduce the absolute value of the maximum current flowing in each steering side motor. Therefore, in order to equalize the current flowing in the two steering side motors, it is sufficient to equalize the load applied to the two steering side motors, i.e., the motor torque of the two steering side motors. As described above (SAT h1 +SAT h2 ) / 2=SAT h1 -T m1 =SAT h2 +T m1 Therefore, in order to equalize the motor torques of the two steering motors, it is only necessary to change the first input torque T of the first steering motor 33 to r1 Subtract the correction interference torque T m1 and the second input torque T from the second steering motor 34 r2 Add the correction interference torque T m1 That's it.

[0204] Here, it is assumed that the steering reaction force is proportional to the current flowing through each steering motor, and the reaction forces of the first steering wheel 21 and the second steering wheel 22 are assisted by the first steering motor 33 and the second steering motor 34. In this case, the interference torque T is not corrected. m1 The sum of the motor torque of the first steering motor 33 and the motor torque of the second steering motor 34 in the case of h1+SAT h2 ) is indicated. In addition, there is a correction interference torque T m1 The sum of the motor torque of the first steering motor 33 and the motor torque of the second steering motor 34 in the case of {(SAT h1 -T m1 )+(SAT h2 +T m1 Since the heat generated by the motor is proportional to the square of the motor torque, by squaring the motor torques represented by the above equations, it is possible to obtain the corrected interference torque T without correcting the interference torque T. m1 The case with corrected interference torque T m1 For example, if the total value of the heat generated by the two steering motors is compared from the correction interference torque T m1 The motor torque in the above equation is squared when the interference torque T is not corrected. m1 The equation obtained by squaring the motor torque in the above equation in the case of becomes the following equation (20).

[0205] 2T m1 2 +2T m1 (SAT h2 -SAT h1 )-2SAT h1 SAT h2

[0206] =2(T m1 -SAT h1 )(T m1 +SAT h2 )···(20)

[0207] When the above equation (20) is a negative value, the interference torque T is not corrected. m1 Compared with the case with correction interference torque T m1 Regarding the condition that the above formula (20) is a negative value, the right term of formula (20) is -SAT h2 <T m1 <SAT h1 As mentioned above, due to T m1 =(SAT h1 -SAT h2 ) / 2, so we know that -SAT is satisfied h2 <T m1 <SAT h1 Therefore, by using the correction interference torque T m1 To control each steering motor, and not to use the correction interference torque T m1Compared with the case of , the heat generated by each steering motor can be suppressed.

[0208] On the other hand, in order to control the two steering motors stably and responsively, it is effective to make the two steering motors non-interfering through the above-mentioned model tracking control, compensate for the torque fluctuations of each steering motor and each second transmission mechanism 25a, 25b connected to each steering motor, and the influence of friction of each part, etc.

[0209] In view of the above, according to the present embodiment, the first model following control unit 63 and the second model following control unit 68 can perform the following control: as the first control cooperative control CT1, the interference torque T m2R , T m2L Included in the correction torque T f1 , T f2 and as a second control of the non-interference control CT2, the correction torque T f1 , T f2 Applied correction interference torque T m2R , T m2L The influence of is smaller than that of the coordinated control CT1. Therefore, the coordinated control CT1 is adopted when the suppression of the heat generation in the first steering motor 33 and the heat generation in the second steering motor 34 is emphasized, and the non-interference control CT2 can be adopted when the stability and responsiveness are emphasized and the first steering motor 33 and the second steering motor 34 are made non-interfering. As a result, while suppressing the output of the first steering motor 33 and the second steering motor 34 from being limited due to self-heating, the stability and responsiveness of each steering motor can be appropriately improved, thereby improving the steering performance of the steering device 100.

[0210] Thus, in the present embodiment, by actively utilizing the torque interference generated between the first steering motor 33 and the second steering motor 34 in the coordinated control CT1, it is possible to suppress the maximum current required by the first steering motor 33 and the second steering motor 34 and the self-heating. As a result, it is easy to reduce the power consumed by the first steering motor 33, the second steering motor 34, the first steering control unit 53, and the second steering control unit 54. In addition, even if the temperature that the first steering motor 33 and the second steering motor 34 can withstand is reduced, it is easy to suppress the output of the first steering motor 33 and the second steering motor 34 from being limited. Therefore, it is possible to reduce the manufacturing cost of the first steering motor 33 and the second steering motor 34.

[0211] The torque fluctuation in each steering motor etc. becomes the resonance frequency ω of the steering device 100 at the steering frequency f. r Or the resonant frequency ω rTherefore, when the steering frequency f becomes the resonant frequency ω of the steering device 100 r Or the resonant frequency ω r When the steering frequency f is close to the resonance frequency ω, the steering device 100 is likely to become unstable and the vehicle travel is likely to become unstable. r Or the resonant frequency ω r In the case of the vicinity of , it is preferable to appropriately compensate for the torque fluctuation by performing the non-interference control CT2, so as to stabilize the steering device 100 and stabilize the running of the vehicle. On the other hand, when the steering frequency f is sufficiently far from the resonance frequency ω r In the case of a frequency of, for example, the steering frequency f is sufficiently lower than the resonance frequency ω r In the case of the above, the vehicle driving and the steering device 100 are not likely to become unstable. Therefore, when the steering frequency f is sufficiently far from the resonance frequency ω r In the case of a frequency of , it is preferable to suppress self-heating in each steering motor by performing cooperative control CT1.

[0212] In view of the above, according to the present embodiment, the steering angle θ which changes due to steering the steering wheel 11 is h The frequency of the steering frequency f is used to switch the coordinated control CT1 and the non-interference control CT2. The steering frequency f when the non-interference control CT2 is executed is higher than the steering frequency f when the coordinated control CT1 is executed. Therefore, when the steering frequency f is relatively high and is close to the resonance frequency ω r In the case of a frequency of ω, the first model tracking control unit 63 and the second model tracking control unit 68 can perform the non-interference control CT2. When the steering frequency f is relatively low and easily becomes far from the resonance frequency ω r In the case of a frequency of , the first model tracking control unit 63 and the second model tracking control unit 68 can perform the coordinated control CT1. Therefore, the coordinated control CT1 and the non-interference control CT2 can be switched appropriately, so that the self-heating of the first steering motor 33 and the self-heating of the second steering motor 34 can be suppressed from excessively increasing while stabilizing the running of the vehicle.

[0213] According to the present embodiment, the cooperative control units 56a and 56b generate the first self-aligning torque estimated value SAT output from the first model following control unit 63 and including the self-aligning torque generated by the first steered wheel 21. h1 The second self-aligning torque estimated value SAT outputted from the second model following control unit 68 and including the self-aligning torque generated by the second steering wheel 22 h2 The value of half the difference is low-pass filtered and is used as the correction interference torque T m2R , T m2LTherefore, the correction interference torque T can be adjusted according to the steering frequency f. m2R , T m2L Specifically, when the steering frequency f is equal to or lower than the cutoff frequency of the low-pass filter that performs the low-pass filtering process, the correction interference torque T is not set. m2R , T m2L The value of the correction torque T can be attenuated. When the steering frequency f is higher than the cutoff frequency of the low-pass filter performing the low-pass filtering process, the correction interference torque T m2R , T m2L Therefore, even if the correction interference torque T m2R , T m2L Always include the correction torque T f1 , T f2 The control in the steering frequency f can also make the correction torque T f1 , T f2 Correction interference torque T m2R , T m2L Therefore, there is no need to switch whether to correct the interference torque T m2R , T m2L Included in the correction torque T f1 , T f2 The control in can automatically switch between coordinated control CT1 and non-interference control CT2.

[0214] According to the present embodiment, the cutoff frequency in the low-pass filtering process performed by the cooperative control units 56a and 56b, that is, the cutoff frequency ω1 in the frequency region setting unit 56d is higher than the mechanical resonance frequency ω in the steering device 100. r Therefore, the steering frequency f becomes the resonance frequency ω r Or the resonant frequency ω r In the case of the vicinity of , the gain in the frequency region setting unit 56d can be reduced, and the correction interference torque T can be easily reduced. m2R , T m2L Therefore, the steering frequency f becomes the resonance frequency ω r Or the resonant frequency ω r In the case of the vicinity of , it is easy to make the control executed in the first model tracking control unit 63 and the second model tracking control unit 68 the non-interference control CT2. In addition, when the steering frequency f is sufficiently lower than the resonance frequency ω r In the case of , it is easy to make the gain in the frequency region setting unit 56d 1, and it is easy to make the correction interference torque T m2R , T m2L The correction torque T is included without attenuation f1 , T f2 Therefore, when the steering frequency f is sufficiently lower than the resonance frequency ω rIn the case of , it is easy to make the control performed in the first model tracking control unit 63 and the second model tracking control unit 68 the coordinated control CT1. In the present embodiment, the first model tracking control unit 63 and the second model tracking control unit 68 perform substantially complete non-interference control CT2 when the steering frequency f is greater than 10 Hz and less than 50 Hz, and perform coordinated control CT1 when the steering frequency f is less than 5 Hz. In the present embodiment, the first model tracking control unit 63 and the second model tracking control unit 68 mainly perform the coordinated control CT1 and partially perform the non-interference control CT2, thereby performing control to compensate for the influence of friction and torque fluctuation. In addition, in the coordinated control CT1, the torque fluctuation and friction of each steering side motor are also compensated by the model tracking control.

[0215] Each functional block in the above-mentioned first steering side control unit 51, second steering side control unit 52, first steering side control unit 53 and second steering side control unit 54 can be installed in each processor provided in each control unit as software such as firmware, can be installed in each processor as hardware, or can be installed in each processor as software and hardware. The processing of each functional block in the processor provided in each control unit is typically described in a computer program in units of software modules and stored in a ROM not shown. However, in the case of using FPGA or the like, all or part of these functional blocks can be installed as a hardware accelerator. In addition, the control method of the control device 50 in the present embodiment described above can be implemented by installing it in a computer and causing the computer to perform the desired action.

[0216] <Second embodiment>

[0217] In the following description, the same structures as those in the above-mentioned embodiment are sometimes appropriately denoted by the same reference numerals and the description thereof is omitted. Fig.17 As shown, the steering device 200 of this embodiment is different from the steering device 100 of the first embodiment in that it does not include the second steering motor 32, the second steering motor 34, the second rotation sensor 84, and the second battery 85b. In other words, the steering device 200 only includes one steering motor, one steering motor, one rotation sensor, and one battery.

[0218] The steering mechanism 220 of this embodiment is different from the steering mechanism 20 of the first embodiment in that it does not have the second transmission mechanism 25b. In the steering mechanism 220 of this embodiment, the second transmission mechanism 25a is connected to the center portion of the rack shaft 23c in the vehicle width direction. The other structures of the steering mechanism 220 are the same as those of the steering mechanism 20 of the first embodiment.

[0219] The control device 250 of the present embodiment is different from the control device 50 of the first embodiment in that it does not include the second steering control unit 52 and the second steering control unit 54. That is, the control device 250 includes only one steering control unit and one steering control unit. The first steering control unit 51 of the control device 250 of the present embodiment performs the same control as the first steering control unit 51 and the second steering control unit 52 in the first embodiment. The first steering control unit 53 of the control device 250 of the present embodiment performs the same control as the first steering control unit 53 and the second steering control unit 54 in the first embodiment. In the control device 250 of the present embodiment, the first model following control unit 63 of the first steering control unit 53 is configured to constrain the transfer function of the controlled object to the transfer function of the nominal model in a frequency band where the gain of the complementary sensitivity function to the modeled error between the controlled object including the first steering motor 33 and the nominal model based on the structure of the controlled object is approximately 1. Therefore, as described in the first embodiment, by appropriately setting the nominal model, the control object can be treated as a desired model. Thus, the responsiveness of each steering wheel relative to the steering of the steering wheel 11 can be appropriately adjusted. Therefore, the steering performance of the steering device 200 can be improved.

[0220] The other structures of the control device 250 are the same as those of the control device 50 in the first embodiment. The other structures of the steering device 200 are the same as those of the steering device 100 in the first embodiment.

[0221] The present invention is not limited to the above-mentioned embodiments, and other structures and other methods can also be adopted within the scope of the technical concept of the present invention. The first nominal model can be a model with any transfer function as long as it is a model based on the structure of the first control object. The second nominal model can be a model with any transfer function as long as it is a model based on the structure of the second control object. The transfer function of the first nominal model can be a function obtained by multiplying other functions by the above-mentioned function F. na The transfer function of the second nominal model may also be obtained by multiplying the above function F by another function. nb (s) and the transfer function obtained. The first control object is not particularly limited as long as it includes the first steering motor. The second control object is not particularly limited as long as it includes the second steering motor. The first control object and the second control object may each include at least a portion of the vehicle body. In this case, the vehicle body rigidity, etc. can be more appropriately compensated. The steering motor and the steering control unit may each be provided with only one.

[0222] In addition, the present technology can adopt the following structures.

[0223] (1) A control device, which is mounted on a steering device of a steer-by-wire type, the steering device being mounted on a vehicle and comprising: a steering mechanism having a steering wheel for a steerer to steer; a steering mechanism having a first steering wheel and a second steering wheel; and a steering motor that drives the steering mechanism, wherein the control device has a steering control unit that controls a control object including the steering motor, the steering control unit having a model tracking control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on a structure of the control object, the model tracking control unit being configured to constrain a transfer function of the control object to be a transfer function of the nominal model in a frequency band where a gain is approximately 1 in a gain characteristic of a complementary sensitivity function of a modeled error between the control object and the nominal model.

[0224] (2) The control device according to (1), wherein the transfer function of the nominal model is a transfer function corresponding to a target value of a mechanical compliance which is a ratio of an output angle of the steering motor to the input torque.

[0225] (3) A control device according to (1), wherein the steering motor includes a first steering motor and a second steering motor, and the steering control unit includes: a first steering control unit, which controls a first control object including the first steering motor; and a second steering control unit, which controls a second control object including the second steering motor, a first interference torque caused by the first steering motor driving the steering mechanism is applied to the second control object, and a second interference torque caused by the second steering motor driving the steering mechanism is applied to the first control object, and the first steering control unit has a first model tracking control unit, which generates a correction for a first input torque input to the first control object based on an output of the first control object and a first nominal model based on a structure of the first control object. The second steering control unit has a second model tracking control unit, which generates a correction torque for correcting a second input torque input to the second control object based on the output of the second control object and a second nominal model based on the structure of the second control object. The first model tracking control unit is configured to constrain the transfer function of the first control object to the transfer function of the first nominal model in a frequency band where the gain in the gain characteristic of the complementary sensitivity function of the modeled error between the first control object and the first nominal model is approximately 1, and the second model tracking control unit is configured to constrain the transfer function of the second control object to the transfer function of the second nominal model in a frequency band where the gain in the gain characteristic of the complementary sensitivity function of the modeled error between the second control object and the second nominal model is approximately 1.

[0226] (4) A control device according to (1), which is mounted on a steering device of a steer-by-wire type, and which is mounted on a vehicle and comprises: a steering mechanism having a steering wheel for a steerer to steer; a steering mechanism having a first steering wheel and a second steering wheel; and a first steering side motor and a second steering side motor, which drive the steering mechanism, wherein the control device comprises: a first steering side control unit which controls a first control object including the first steering side motor; and a second steering side control unit which controls a second control object including the second steering side motor, since the A first interference torque caused by the first steering side motor driving the steering mechanism is applied to the second control object, a second interference torque caused by the second steering side motor driving the steering mechanism is applied to the first control object, the first steering side control unit compensates for the second interference torque by constraining the transfer function of the first control object to be a model tracking control of a transfer function based on a first nominal model of the structure of the first control object, and the second steering side control unit compensates for the first interference torque by constraining the transfer function of the second control object to be a model tracking control of a transfer function based on a second nominal model of the structure of the second control object.

[0227] (5) A control device according to (3) or (4), wherein the transfer function of the first nominal model is a transfer function corresponding to a target value of mechanical compliance which is a ratio of an output angle of the first steering motor to the first input torque, and the transfer function of the second nominal model is a transfer function corresponding to a target value of mechanical compliance which is a ratio of an output angle of the second steering motor to the second input torque.

[0228] (6) The control device according to (5), wherein the first controlled object includes the first steering wheel, and the second controlled object includes the second steering wheel.

[0229] (7) The control device according to (6), wherein the first controlled object and the second controlled object each include at least one bushing provided in the steering mechanism.

[0230] (8) The control device according to (7), wherein the transfer function of the first nominal model includes at least a function F represented by the following equation: na (s):

[0231]

[0232] Where s is the Laplace transform, J m1 is a parameter equivalent to the inertia moment of the first steering motor, B m1is a parameter equivalent to the viscous friction coefficient of the first steering motor, J Tyre1 is the parameter equivalent to the inertia moment of the first steering wheel, B Tyre1 is a parameter equivalent to the viscous friction coefficient of the first steering wheel, K Bush1 is a parameter corresponding to an equivalent spring constant of an elastic element including the bush in the first controlled object, and G1 is a parameter corresponding to a gear ratio from the first steering-side motor to the first steering wheel.

[0233] (9) The control device according to (7) or (8), wherein the transfer function of the second nominal model includes at least a function F represented by the following equation: nb (s):

[0234]

[0235] Where s is the Laplace transform, J m2 is a parameter equivalent to the inertia moment of the second steering motor, B m2 is a parameter equivalent to the viscous friction coefficient of the second steering motor, J Tyre2 is the parameter equivalent to the inertia moment of the second steering wheel, B Tyre2 is the parameter equivalent to the viscous friction coefficient of the second steering wheel, K Bush2 G2 is a parameter corresponding to the equivalent spring constant of the elastic element including the bush in the second controlled object, and G3 is a parameter corresponding to the gear ratio from the second steering-side motor to the second steering wheel.

[0236] (10) A control device according to any one of (6) to (9), wherein the control device has a steering reaction force control unit, which controls the steering reaction force transmitted to the helmsman via the steering wheel, the first model tracking control unit calculates a first inferred value including the second interference torque based on the difference between the torque calculated using the first nominal model based on the output of the first control object and the first input torque, the second model tracking control unit calculates a second inferred value including the first interference torque based on the difference between the torque calculated using the second nominal model based on the output of the second control object and the second input torque, and the steering reaction force control unit controls the reaction force transmitted to the helmsman based on a total value obtained by adding the first inferred value to the second inferred value.

[0237] (11) The control device according to any one of (6) to (10), wherein the first control object and the second control object each include at least a portion of a vehicle body.

[0238] (12) A control device according to any one of (3) to (11), wherein the control device has a coordination control unit, which generates a correction interference torque based on a value output from the first model tracking control unit and a value output from the second model tracking control unit, and the first model tracking control unit and the second model tracking control unit are capable of performing the following controls: a first control in which the correction interference torque is included in the correction torque for control; and a second control in which the correction interference torque under the second control has a smaller effect on the correction torque than the first control.

[0239] (13) A control device according to (12), wherein the first control and the second control are switched according to a frequency of a steering angle that changes due to steering the steering wheel, i.e., a steering frequency, and the steering frequency when executing the second control is higher than the steering frequency when executing the first control.

[0240] (14) A control device according to (13), wherein the coordination control unit generates a value as the correction interference torque by low-pass filtering a value which is half of the difference between an estimated value output from the first model tracking control unit and including the automatic self-aligning torque generated by the first steering wheel and an estimated value output from the second model tracking control unit and including the automatic self-aligning torque generated by the second steering wheel.

[0241] (15) The control device according to (14), wherein a cutoff frequency in the low-pass filter processing is lower than a mechanical resonance frequency in the steering device.

[0242] (16) A steering device, which is a steering device of a steer-by-wire type, wherein the steering device comprises: a steering mechanism having a steering wheel for a helmsman to steer; a steering mechanism having a first steering wheel and a second steering wheel; a first steering side motor and a second steering side motor, wherein the first steering side motor and the second steering side motor drive the steering mechanism; and a control device as described in any one of (3) to (15).

[0243] (17) A steering device according to (16), wherein the stator in the first steering motor has a plurality of coil groups, and in the first steering motor, the coil groups of different systems are arranged rotationally symmetrically around a central axis of the first steering motor.

[0244] (18) The steering device according to (17), wherein the first steering control unit includes a plurality of inverter circuits for independently supplying electric power to the plurality of coil groups in the first steering motor.

[0245] (19) A steering device according to (18), wherein the stator in the second steering side motor has a plurality of systems of coil groups, and in the second steering side motor, the coil groups of different systems are rotationally symmetrically arranged around a central axis of the second steering side motor, and the second steering side control unit has a plurality of inverter circuits for independently supplying power to the plurality of systems of coil groups in the second steering side motor.

[0246] (20) A steering device according to any one of (16) to (19), wherein the steering device has a first steering side motor and a second steering side motor capable of driving the steering mechanism, and the control device has: a first steering side control unit, which controls the first steering side motor; and a second steering side control unit, which controls the second steering side motor, the first steering side control unit and the first steering side control unit can communicate with each other, and the second steering side control unit and the second steering side control unit can communicate with each other.

[0247] The structures and methods described above in this specification can be appropriately combined within a range that does not contradict each other.

Claims

1. A control device mounted on a steering device of a steer-by-wire type, The steering device is mounted on a vehicle and has: A steering mechanism having a steering wheel for the helmsman to steer; A steering mechanism having a first steering wheel and a second steering wheel; and A steering motor drives the steering mechanism. in, The control device includes a steering control unit that controls a control object including the steering motor. The steering control unit includes a model following control unit that generates a correction torque for correcting an input torque input to the control object based on an output of the control object and a nominal model based on a structure of the control object. The model following control unit is configured to constrain a transfer function of the controlled object to a transfer function of the nominal model in a frequency band where a gain is substantially 1 in a gain characteristic of a complementary sensitivity function with respect to a modeled error between the controlled object and the nominal model.

2. The control device according to claim 1, wherein: The transfer function of the nominal model is a transfer function corresponding to a target value of a mechanical compliance which is a ratio of an output angle of the steering motor to the input torque.

3. The control device according to claim 1, wherein: The steering motor includes a first steering motor and a second steering motor. The steering control unit includes: a first steering control unit that controls a first control object including the first steering motor; and a second steering control unit for controlling a second control object including the second steering motor; A first interference torque caused by the first steering motor driving the steering mechanism is applied to the second controlled object. A second interference torque caused by the second steering motor driving the steering mechanism is applied to the first controlled object. The first steering control unit includes a first model tracking control unit that generates a correction torque for correcting a first input torque input to the first control object based on an output of the first control object and a first nominal model based on a structure of the first control object. The second steering control unit includes a second model following control unit that generates a correction torque for correcting a second input torque input to the second controlled object based on an output of the second controlled object and a second nominal model based on a structure of the second controlled object. The first model tracking control unit is configured to constrain a transfer function of the first controlled object to be a transfer function of the first nominal model in a frequency band where a gain is substantially 1 in a gain characteristic of a complementary sensitivity function with respect to a modeled error between the first controlled object and the first nominal model, The second model tracking control unit is configured to constrain the transfer function of the second controlled object to the transfer function of the second nominal model in a frequency band where the gain of the gain characteristic of the complementary sensitivity function with respect to the modeled error between the second controlled object and the second nominal model is substantially 1.

4. The control device according to claim 1, wherein: The steering motor includes a first steering motor and a second steering motor. The steering control unit includes: a first steering control unit that controls a first control object including the first steering motor; and a second steering control unit for controlling a second control object including the second steering motor; A first interference torque caused by the first steering motor driving the steering mechanism is applied to the second controlled object. A second interference torque caused by the second steering motor driving the steering mechanism is applied to the first controlled object. The first steering control unit compensates for the second interference torque by a model following control in which a transfer function of the first controlled object is constrained to a transfer function of a first nominal model of the structure of the first controlled object. The second steering control unit compensates for the first interference torque by performing model following control in which a transfer function of the second controlled object is constrained to a transfer function based on a second nominal model of the structure of the second controlled object.

5. The control device according to claim 3, wherein: The transfer function of the first nominal model is a transfer function corresponding to a target value of a mechanical compliance which is a ratio of an output angle of the first steering motor to the first input torque. The transfer function of the second nominal model is a transfer function corresponding to a target value of a mechanical compliance which is a ratio of an output angle of the second steering motor to the second input torque.

6. The control device according to claim 5, wherein: The first controlled object includes the first steering wheel, The second controlled object includes the second steering wheel.

7. The control device according to claim 6, wherein: The first controlled object and the second controlled object each include at least one bushing provided in the steering mechanism.

8. The control device according to claim 7, wherein: The transfer function of the first nominal model at least includes a function F represented by the following formula: na (s): Where s is the Laplace transform, J m1 is a parameter equivalent to the inertia moment of the first steering motor, B m1 is a parameter equivalent to the viscous friction coefficient of the first steering motor, J Tyre1 is the parameter equivalent to the inertia moment of the first steering wheel, B Tyre1 is a parameter equivalent to the viscous friction coefficient of the first steering wheel, K Bush1 is a parameter corresponding to an equivalent spring constant of an elastic element including the bush in the first controlled object, and G1 is a parameter corresponding to a gear ratio from the first steering-side motor to the first steering wheel.

9. The control device according to claim 7, wherein: The transfer function of the second nominal model at least includes a function F represented by the following formula: nb (s): Where s is the Laplace transform, J m2 is a parameter equivalent to the inertia moment of the second steering motor, B m2 is a parameter equivalent to the viscous friction coefficient of the second steering motor, J Tyre2 is the parameter equivalent to the inertia moment of the second steering wheel, B Tyre2 is the parameter equivalent to the viscous friction coefficient of the second steering wheel, K Bush2 G2 is a parameter corresponding to the equivalent spring constant of the elastic element including the bush in the second controlled object, and G3 is a parameter corresponding to the gear ratio from the second steering-side motor to the second steering wheel.

10. The control device according to claim 6, wherein: The control device includes a steering reaction force control unit that controls the steering reaction force transmitted to the steersman via the steering wheel. The first model following control unit calculates a first estimated value including the second interference torque based on a difference between the torque calculated using the first nominal model based on the output of the first controlled object and the first input torque. The second model following control unit calculates a second estimated value including the first interference torque based on a difference between the torque calculated using the second nominal model based on the output of the second controlled object and the second input torque. The steering reaction force control unit controls the reaction force transmitted to the steering operator based on a total value obtained by adding the first estimated value to the second estimated value.

11. The control device according to claim 6, wherein: The first control object and the second control object each include at least a portion of a vehicle body.

12. The control device according to claim 3, wherein: The control device includes a coordination control unit that generates a correction interference torque based on a value output from the first model following control unit and a value output from the second model following control unit. The first model tracking control unit and the second model tracking control unit can perform the following control: a first control of controlling by including the correction interference torque in the correction torque; as well as A second control in which the correction interference torque has a smaller influence on the correction torque than the first control.

13. The control device according to claim 12, wherein: switching the first control and the second control according to a steering frequency which is a frequency of a steering angle that changes when the steering wheel is steered, The steering frequency when the second control is performed is higher than the steering frequency when the first control is performed.

14. The control device according to claim 13, wherein: The coordination control unit generates, as the correction interference torque, a value obtained by low-pass filtering a half of a value of a difference between an estimated value output from the first model following control unit and including the self-aligning torque generated by the first steering wheel and an estimated value output from the second model following control unit and including the self-aligning torque generated by the second steering wheel.

15. The control device according to claim 14, wherein: The cutoff frequency in the low-pass filter process is lower than a mechanical resonance frequency in the steering device.

16. A steering device, which is a steer-by-wire steering device, wherein: The steering device has: A steering mechanism having a steering wheel for the helmsman to steer; A steering mechanism having a first steering wheel and a second steering wheel; a first steering motor and a second steering motor, the first steering motor and the second steering motor driving the steering mechanism; and A control device as claimed in any one of claims 3 to 15.

17. The steering device according to claim 16, wherein: The stator in the first steering motor has a plurality of coil groups. In the first steering motor, the coil groups of different systems are arranged rotationally symmetrically around a central axis of the first steering motor.

18. The steering device according to claim 17, wherein: The first steering control unit includes a plurality of inverter circuits for independently supplying electric power to the plurality of coil groups in the first steering motor.

19. The steering device according to claim 18, wherein: The stator in the second steering motor has a plurality of coil groups. In the second steering motor, the coil groups of different systems are arranged rotationally symmetrically around a central axis of the second steering motor. The second steering control unit includes a plurality of inverter circuits for independently supplying electric power to the plurality of coil groups in the second steering motor.

20. The steering device according to claim 16, wherein: The steering device includes a first steering motor and a second steering motor capable of driving the steering mechanism. The control device has: a first steering side control unit, which controls the first steering side motor; as well as a second steering side control unit that controls the second steering side motor, The first steering control unit and the first turning control unit are capable of communicating with each other. The second steering control unit and the second turning control unit are capable of communicating with each other.

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