Steering system

Abstract

A steering system configured such that electric power is supplied from a first power supply to a steering actuator (12) and a turning actuator (31) when an electric power state of a vehicle is an on state, and the electric power supply from the first power supply is cut off when the electric power state is an off state. The steering system includes a rotation suppression unit configured to operate such that rotation of a steering wheel (3) is suppressed in at least a part of a first power-off period as an operation period from when the electric power state changes to the off state until the electric power state next changes to the on state, and a second power supply configured to supply electric power required for operation of the rotation suppression unit to the rotation suppression unit in the operation period, the second power supply being different from the first power supply.

Description

Technical Field

[0001] This invention relates to steering systems. Background Technology

[0002] For example, a steering system installed in a vehicle includes a steering unit that operates to apply a steering reaction force to the vehicle's steering wheel and a turning unit that operates to turn the vehicle's turning wheels. Japanese Unexamined Patent Application Publication No. 2020-11646 (JP 2020-11646 A) discloses a steer-by-wire system with a structure in which the power transmission path between the steering unit and the turning unit is cut off as an example.

[0003] In JP 2020-11646 A, the angle difference between the steering wheel angle and the turning wheel angle can be reduced even when the ignition switch, which indicates the vehicle's electrical status, is in the off position. Specifically, a steering locking device that locks the rotational operation of the steering wheel is attached to the column shaft of the steering unit. The steering locking device is configured to operate such that the rotational operation of the steering wheel is locked after the ignition switch is turned off. Summary of the Invention

[0004] The steering lock device in JP 2020-11646 A operates after the ignition switch is turned off. In this case, in order to ensure that the vehicle's power supply is adequate when the ignition switch is turned on again, it is necessary to properly ensure the power required for the operation of the steering lock device even when the ignition switch is off.

[0005] According to one aspect of the invention, a steering system is provided, comprising: a steering actuator configured to operate using power supplied from a first power source installed in a vehicle, such that a steering reaction force is applied to a steering wheel of the vehicle; and a turning actuator having a structure in which a power transmission path between the turning actuator and the steering actuator is interrupted, the turning actuator being configured to operate using power supplied from the first power source, such that the turning wheels of the vehicle turn. The steering system is configured such that when the vehicle's power state is on, power is supplied from the first power source to the steering actuator and the turning actuator, and when the power state is off, the power supply from the first power source is interrupted. The steering system further comprises: a rotation suppression unit configured to operate such that rotation of the steering wheel is suppressed during at least a portion of an operating period from when the power state changes to off until when the power state changes to on once; and a second power source configured to supply power required for operation of the rotation suppression unit to the rotation suppression unit during the operating period, the second power source being different from the first power source.

[0006] With this configuration, during at least a portion of the operation period when power from the first power outage is cut off, the power required for the operation of the rotation suppression unit is supplied from the second power source. In other words, when the rotation suppression unit operates during the operation period, power does not need to be supplied from the first power source. Therefore, even when the rotation suppression unit is operating during the first power outage period, power consumption from the first power source can be suppressed. In this case, the power required for the operation of the rotation suppression unit during a vehicle power outage can be appropriately ensured so that the vehicle's first power source can supply power normally when the vehicle is powered on again.

[0007] In the steering system, the operation period can coincide with the first power-off period in relation to the vehicle's state. This structure can appropriately suppress the angular difference between the steering wheel angle and the turning wheel angle.

[0008] In the steering system, the operating period, with respect to the driver's state and the vehicle's state, can be the period during which the driver is within a predetermined distance from the vehicle during the first power-off period. The rotation suppression unit can be configured to operate during the period during which the driver is within the predetermined distance from the vehicle, even when the power is off.

[0009] For example, during the first power outage period, when the driver is near the vehicle, there is a high probability that the driver may touch the steering wheel. In this case, according to this configuration, the rotation suppression unit can operate even when the driver is away from the vehicle and there is a high probability that the driver may touch the steering wheel. In this situation, the period during which the rotation suppression unit operates—that is, the operating period—can be set to be shorter than the first power outage period. This is effective in suppressing power consumption from the second power source.

[0010] The steering system may also include an electronic control unit configured to determine the driver's state. The electronic control unit may be configured to determine the driver's state based on at least one of the following: i) the key position of the vehicle key relative to the vehicle; ii) the key position and the locking status of the doors when the driver enters the vehicle and when the driver exits the vehicle; and iii) the key position and the open-closed status of the doors.

[0011] This configuration allows the system to determine whether the driver is in the vehicle and the likelihood of the driver having contact with the steering wheel based on the key position. Based on the key position and the door's lock status, the system can more accurately determine whether the driver is in the vehicle and the likelihood of the driver having contact with the steering wheel. This is the same as based on the key position and the door's open / closed status. Therefore, the electronic control unit can appropriately determine whether the driver is away from or near the vehicle.

[0012] In a steering system, the steering actuator may include a reaction force motor configured to generate motor torque as a power source for applying steering reaction force to the steering wheel, and the rotation suppression unit may be a reaction force motor.

[0013] When a reaction motor is used as the rotation suppression unit in this configuration, power needs to be supplied to at least the steering actuator so that it can operate during the first power-off period. This configuration allows power to be supplied to the steering actuator while suppressing the load on the primary power source during the first power-off period. Therefore, by using a reaction motor as the rotation suppression unit, the power required for the reaction motor's operation during a vehicle power outage can be adequately ensured so that the vehicle's primary power source can supply power normally when the ignition switch is turned on again. In this case, a relatively low-power mechanical structure is not required as the rotation suppression unit. This is effective for reducing the size of the steering system—especially the steering actuator—simplifies its configuration, and lowers manufacturing costs.

[0014] In the steering system, the second power source can be configured to supply power to the steering actuator and the turning actuator in place of the first power source when the power supplied by the first power source is reduced or cut off when the power state is on.

[0015] With this configuration, for example, when the steering system includes a backup power source that alternatively supplies power to the steering actuator and turning actuator instead of the first power source, the backup power source can be used as a second power source. In this case, the degree of modification required to add the configuration for the second power source to the steering system can be reduced.

[0016] With the steering system according to one aspect of the invention, the power required for the operation of the rotation suppression unit can be adequately ensured even when the vehicle's electrical state is off. Attached Figure Description

[0017] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which similar reference numerals denote similar elements, and in the drawings:

[0018] Figure 1 This is a diagram schematically illustrating the configuration of the steer-by-wire system according to the first embodiment;

[0019] Figure 2 It is a schematic diagram illustrating the power supply system;

[0020] Figure 3 This is a diagram illustrating the power supply mode according to the first embodiment;

[0021] Figure 4 This is a block diagram illustrating the function of the steering control device according to the first embodiment;

[0022] Figure 5A and Figure 5B This is a diagram illustrating details of the control performed according to the power supply mode in accordance with the first embodiment;

[0023] Figure 6 It is a timing diagram including portions (a) and (b) showing the details of the control performed based on the power supply mode according to the first embodiment;

[0024] Figure 7 This is a block diagram illustrating the function of the auxiliary power control unit of the auxiliary power supply device according to the second embodiment;

[0025] Figure 8 This is a diagram illustrating the power supply mode according to the second embodiment;

[0026] Figure 9A and Figure 9BThis is a diagram illustrating details of the control performed based on the power supply mode according to the second embodiment; and

[0027] Figure 10 This is a timing diagram including portions (a) to (c) showing the details of the control performed according to the power supply mode based on the second embodiment. Detailed Implementation

[0028] First Implementation Method

[0029] In the following description, a steering system according to a first embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, the steering system 1 according to this embodiment is a steer-by-wire vehicle steering system. The steering system 1 includes a steering control device 2 that controls the operation of the steering system 1. The steering system 1 includes a steering unit 4 and a turning unit 6. The steering unit 4 is steered by the driver via the vehicle's steering wheel 3. The turning unit 6 turns the vehicle's left and right turning wheels 5 according to the steering input from the driver to the steering unit 4. The steering system 1 according to this embodiment has a structure in which the power transmission path between the steering unit 4 and the turning unit 6 is generally mechanically disconnected. That is, the power transmission path between the steering actuator 12, which will be described later, and the turning actuator 31, which will be described later, is generally mechanically disconnected.

[0030] The steering unit 4 includes a steering shaft 11 and a steering actuator 12. The steering shaft 11 is connected to the steering wheel 3. The steering actuator 12 includes a steering-side motor 13 as a drive source and a steering-side reduction mechanism 14. The steering-side motor 13 is a reaction force motor that applies a steering reaction force against steering to the steering wheel 3 via the steering shaft 11. The steering-side motor 13 is connected to the steering shaft 11, for example, via the steering-side reduction mechanism 14 formed by a worm and a worm wheel. For example, a three-phase brushless motor is used as the steering-side motor 13 according to this embodiment.

[0031] The turning unit 6 includes a pinion shaft 21, a rack shaft 22 serving as a turning axis, and a rack housing 23. The pinion shaft 21 and the rack shaft 22 are connected at a predetermined cross angle. A rack and pinion mechanism 24 is formed by meshing the pinion teeth 21a formed in the pinion shaft 21 and the rack teeth 22a formed in the rack shaft 22 with each other. That is, the pinion shaft 21 is a rotation axis corresponding to the rotation angle of which can be converted into the turning angle of the turning wheel 5. The rack housing 23 houses the rack and pinion mechanism 24. The end of the pinion shaft 21 opposite to the end connected to the rack shaft 22 protrudes from the rack housing 23. The two ends of the rack shaft 22 protrude from the two ends of the rack housing 23 in the axial direction. A tie rod 26 is connected to the two ends of the rack shaft 22 via rack ends 25, each of which is formed by a ball joint. The distal end of the tie rod 26 is connected to the steering knuckle (not shown) to which the right turning wheel 5 and the left turning wheel 5 are assembled.

[0032] The turning unit 6 includes a turning actuator 31. The turning actuator 31 includes a turning-side motor 32 as a drive source, a transmission mechanism 33, and a conversion mechanism 34. The turning-side motor 32 applies a turning force to the rack shaft 22 via the transmission mechanism 33 and the conversion mechanism 34 to turn the turning wheel 5. The turning-side motor 32 transmits rotation to the conversion mechanism 34, for example, via the transmission mechanism 33, which is formed by a belt drive mechanism. The transmission mechanism 33 converts the rotation of the turning-side motor 32 into the reciprocating motion of the rack shaft 22 via the conversion mechanism 34, for example, which is formed by a ball screw mechanism. For example, a three-phase brushless motor is used as the turning-side motor 32 according to this embodiment.

[0033] In the steering system 1 with the aforementioned configuration, the turning angle of the steering wheel 5 is changed by applying a motor torque, which serves as a turning force, from the steering actuator 31 to the rack shaft 22 according to the driver's steering operation. At this time, a steering reaction force opposing the driver's steering is applied from the steering actuator 12 to the steering wheel 3. In other words, in the steering system 1, the steering torque Th required to turn the steering wheel 3 is changed by the steering reaction force, which is the motor torque applied from the steering actuator 12.

[0034] The reason for providing the pinion shaft 21 is that the rack shaft 22 is supported together with the pinion shaft 21 in the rack housing 23. That is, the rack shaft 22 is supported so that it can move in its axial direction and is pressed towards the pinion shaft 21 by a support mechanism (not shown) provided in the steering system 1. Therefore, the rack shaft 22 is supported in the rack housing 23. Alternatively, a separate support mechanism could be provided to support the rack shaft 22 in the rack housing 23 without using the pinion shaft 21.

[0035] Electrical configuration of steering system 1

[0036] like Figure 1As shown, the steering-side motor 13 and the turning-side motor 32 are connected to the steering control device 2. The steering control device 2 controls the operation of the steering-side motor 13 and the turning-side motor 32.

[0037] Torque sensor 41, steering side rotation angle sensor 42, cornering side rotation angle sensor 43, and vehicle speed sensor 44 are connected to steering control unit 2. Torque sensor 41 detects steering torque Th, which is a value indicating the torque applied to steering shaft 11 according to the driver's steering operation. Torque sensor 41 is disposed in a portion of steering shaft 11, which is closer to steering wheel 3 than steering side deceleration mechanism 14. Torque sensor 41 detects steering torque Th based on the amount of torsion of torsion bar 41a disposed at a location in steering shaft 11. For example, when performing a right turn, steering torque Th is detected as a positive value, while when performing a left turn, steering torque Th is detected as a negative value.

[0038] The steering-side rotation angle sensor 42 detects the rotation angle θa, which is the angle of the rotation axis of the steering-side motor 13, within a 360° range. The steering-side rotation angle sensor 42 is disposed in the steering-side motor 13. The rotation angle θa of the steering-side motor 13 is used to calculate the steering angle θs. The steering-side motor 13 and the steering shaft 11 operate in conjunction with each other via the steering-side reduction mechanism 14. Therefore, there is a correlation between the rotation angle θa of the steering-side motor 13 and the rotation angle of the steering shaft 11, and thus, there is a correlation between the rotation angle θa of the steering-side motor 13 and the steering angle θs, which is the rotation angle of the steering wheel 3. Therefore, the steering angle θs can be calculated based on the rotation angle θa of the steering-side motor 13. For example, when performing a right turn, the rotation angle θa is detected as a positive value, while when performing a left turn, the rotation angle θa is detected as a negative value.

[0039] The turning-side rotation angle sensor 43 detects the rotation angle θb, which is the angle of the rotation axis of the turning-side motor 32, within a 360-degree range. The turning-side rotation angle sensor 43 is installed in the turning-side motor 32. The rotation angle θb of the turning-side motor 32 is used to calculate the pinion angle θp. The turning-side motor 32 and the pinion shaft 21 operate in conjunction with each other via a transmission mechanism 33, a conversion mechanism 34, and a rack and pinion mechanism 24. Therefore, there is a correlation between the rotation angle θb of the turning-side motor 32 and the pinion angle θp, which is the rotation angle of the pinion shaft 21. Therefore, the pinion angle θp can be calculated based on the rotation angle θb of the turning-side motor 32. The pinion shaft 21 meshes with the rack shaft 22. Therefore, there is also a correlation between the pinion angle θp and the amount of movement of the rack shaft 22. That is, the pinion angle θp is the value in which the turning angle of the turning wheel 5 is reflected. For example, when performing a right turn, the rotation angle θb is detected as a positive value, while when performing a left turn, the rotation angle θb is detected as a negative value.

[0040] Vehicle speed sensor 44 detects vehicle speed V, which is configured to indicate the vehicle's travel speed. Vehicle speed sensor 44 can be connected to a vehicle-side control unit installed in the vehicle as a control unit other than steering control unit 2. In this case, the vehicle speed V is transmitted from the vehicle-side control unit via... Figure 1 The vehicle network 45 (e.g., CAN) input, indicated by alternating long and two short dashed lines, is sent to the steering control unit 2.

[0041] The main power supply 46 is connected to the steering control device 2, i.e., the steering system 1. The main power supply 46 is a secondary battery installed in the vehicle, used as a power source to supply power to motors 13 and 32, enabling them to operate, and also as a power source to supply power to the steering control device 2, i.e., the steering system 1, enabling it to operate. In this embodiment, the main power supply 46 is an example of a first power source.

[0042] A vehicle start switch 47 is provided between the steering control device 2 and the main power supply 46. Figure 1 (Indicated by "SW"), for example, an ignition switch. The start switch 47 is located on power line L2, a branch of power line L1 from the two power lines L1 and L2 connecting the steering control device 2 and the main power supply 46. The start switch 47 is operated when various functions are activated, allowing the vehicle to be operated by its driving force, such as the engine. Operation of the start switch 47 connects and disconnects power line L2. In this embodiment, the operating state of the steering system 1 is associated with the operating state of the vehicle. Power line L1 is essentially normally connected, and is indirectly connected and disconnected according to the operating state of the steering system 1, along with the functions of the steering system 1. That is, the operating state of the steering system 1 is associated with the on and off states of power lines L1 and L2, which are the power supply states of the main power supply 46.

[0043] like Figure 2 As shown, the steering control device 2 includes a steering side control unit 50, a turning side control unit 60, and an auxiliary power supply unit 70. The steering side control unit 50 controls the power supply to the steering side motor 13. The turning side control unit 60 controls the power supply to the turning side motor 32. The steering side control unit 50 and the turning side control unit 60 send and receive information via a local area network 48, such as a serial communication network. The steering side control unit 50 is configured as part of the steering unit 4—that is, the steering actuator 12. The turning side control unit 60 is configured as part of the turning unit 6—that is, the turning actuator 31.

[0044] Power lines L1 and L2, i.e., main power supply 46, are connected via auxiliary power supply 70 to the steering side control unit 50, which is part of the configuration of steering actuator 12, and the turning side control unit 60, which is part of the configuration of turning actuator 31. That is, in this embodiment, the steering actuator 12 and the turning actuator 31 share a single auxiliary power supply 70.

[0045] The auxiliary power supply unit 70 includes an auxiliary power supply 71 and an auxiliary power supply control unit 72. For example, the auxiliary power supply 71 is a capacitor, such as a lithium-ion capacitor, that functions similarly to a secondary battery. The auxiliary power supply 71 serves as a power source supplying power to the steering actuator 12 to operate it, to the steering-side motor 13 to operate it, and to the steering-side control unit 50 to operate it. Similarly, the auxiliary power supply 71 serves as a power source supplying power to the turning actuator 31 to operate it, to the turning-side motor 32, and to the turning-side control unit 60. The auxiliary power supply 71 assists in supplying power to the steering-side control unit 50 and the turning-side control unit 60 based on the state of power supply from the main power supply 46. In the event of a reduction or interruption of power supply from the main power supply 46, the auxiliary power supply 71 serves as a backup power source to supply power to the steering-side control unit 50 and the turning-side control unit 60 in place of the main power supply 46. In this embodiment, the auxiliary power supply 71 is an example of a second power supply.

[0046] The auxiliary power control unit 72 has the function of switching the connection state with the power line L1 for the purpose of charging and discharging the auxiliary power supply 71, and includes, for example, a central processing unit (CPU) and a memory. The CPU of the auxiliary power control unit 72 executes the program stored in the memory at predetermined calculation cycle intervals. Therefore, various processes are performed. The auxiliary power control unit 72 is configured to communicate with the steering side control unit 50 via a dedicated signal line 49. On the other hand, the auxiliary power control unit 72 is not configured to communicate with the turning side control unit 60 via a dedicated signal line. This is because, in the steering system 1, the location of the auxiliary power device 70 according to this embodiment is set closer to the steering unit 4 between the steering unit 4 and the turning unit 6.

[0047] In this embodiment, the auxiliary power supply 70 is provided as an auxiliary power supply for the steering actuator 12 and the turning actuator 31 (i.e., the steering system 1). The auxiliary power supply 70, the steering side control unit 50, and the turning side control unit 60 constitute the power supply system D. The power supply system D is used as the power supply system for the steering actuator 12 and the turning actuator 31 (i.e., the steering system 1).

[0048] Power supply mode of power system D

[0049] like Figure 3 As shown, the power supply system D determines the power supply mode as the mode for supplying power to the auxiliary power control unit 72, the steering side control unit 50, and the turning side control unit 60 based on the on or off state of the start switch 47 (“SW”, “ON”, or “OFF” in the figure).

[0050] When the start switch 47 is in the open position, the power system D performs control to supply power to all control units 50, 60, and 72. In this case, power is supplied to control units 50, 60, and 72 from at least one of the main power supply 46 and the auxiliary power supply 71. That is, when the start switch 47 is in the open position, power is supplied to the steering actuator 12 and the turning actuator 31 from at least one of the main power supply 46 and the auxiliary power supply 71.

[0051] When the start switch 47 is in the off state, the power system D performs control to supply power to the auxiliary power control unit 72 and the steering side control unit 50, and performs control to cut off the power supply to the turning side control unit 60. In this case, power is supplied from the auxiliary power source 71 to the auxiliary power control unit 72 and the steering side control unit 50. In this embodiment, even when the power supply from the main power source 46 is cut off, the auxiliary power control unit 72 and the steering side control unit 50 can use the auxiliary power source 71 to ensure the power required for their operation. That is, when the start switch 47 is in the off state, power is supplied from the auxiliary power source 71 to the steering actuator 12.

[0052] like Figure 2 As shown, the auxiliary power control unit 72 operates using power supplied from at least one of the main power supply 46 and the auxiliary power supply 71, and generates a power status signal Sst that indicates the on or off state of the start switch 47. When the start switch 47 is in the on state, the auxiliary power control unit 72 generates a power status signal Sst of "0" (zero value) indicating the on state. When the start switch 47 is in the off state, the auxiliary power control unit 72 generates a power status signal Sst of "1" indicating the off state. The generated power status signal Sst is output to the steering-side control unit 50 via a dedicated signal line 49.

[0053] Functions of steering control device 2

[0054] In the steering control device 2, each of the steering-side control unit 50 and the turning-side control unit 60 includes a central processing unit (CPU) and a memory (not shown). The CPU of each of the steering-side control unit 50 and the turning-side control unit 60 executes a program stored in the memory at predetermined calculation cycle intervals. Thus, various processes are performed.

[0055] exist Figure 4 The diagram shows a portion of the processing performed by the steering side control unit 50 and the cornering side control unit 60. Figure 4 This illustrates a portion of each type of processing achieved by having the CPU execute programs stored in memory.

[0056] The steering-side control unit 50 includes a steering-side current sensor 55. The steering-side current sensor 55 detects the actual steering-side current value Ia, obtained from the value of the phase current of the steering-side motor 13, which flows in the connection line between the steering-side control unit 50 and the phase motor coil of the steering-side motor 13. The steering-side current sensor 55 also captures the voltage drop as current from the shunt resistor connected to the source side of each switching element in an inverter (not shown) corresponding to the steering-side motor 13. Figure 4 For ease of description, the connected wiring is shown as a single line, and the phase current sensor is shown as a single sensor.

[0057] The turning-side control unit 60 includes a turning-side current sensor 64. The turning-side current sensor 64 detects the actual turning-side current value Ib, obtained from the value of the phase current of the turning-side motor 32, which flows in the connection line between the turning-side control unit 60 and the phase motor coil of the turning-side motor 32. The turning-side current sensor 64 obtains the voltage drop as current from the shunt resistor connected to the source side of each switching element in an inverter (not shown) corresponding to the turning-side motor 32. Figure 4 For ease of description, the connected wiring is shown as a single line, and the phase current sensor is shown as a single sensor.

[0058] Steering side control unit 50

[0059] like Figure 4 As shown, the steering torque Th, vehicle speed V, rotation angle θa, actual turning current value Ib, pinion angle θp, and power state signal Sst are input to the steering side control unit 50. The steering side control unit 50 controls the power supply to the steering side motor 13 based on the steering torque Th, vehicle speed V, rotation angle θa, actual turning current value Ib, pinion angle θp, and power state signal Sst.

[0060] The steering-side control unit 50 includes a steering angle calculation unit 51, a steering-side normal control unit 52, a steering lock control unit 53, and a power control unit 54. The rotation angle θa is input to the steering angle calculation unit 51. The steering angle calculation unit 51 converts the rotation angle θa into a total angle within a range exceeding 360 degrees, for example, by counting the number of rotations of the steering-side motor 13 from the steering neutral position (which is the position of the steering wheel 3 when the vehicle is moving forward in a straight line). The steering angle calculation unit 51 calculates the steering angle θs by multiplying the total angle obtained through conversion by a conversion factor based on the rotational speed ratio of the steering-side reduction mechanism 14. The obtained steering angle θs is output to the steering lock control unit 53. The steering angle θs is also output to the turning-side control unit 60.

[0061] The steering-side control unit 52 typically includes a target reaction torque calculation unit 52a. The steering torque Th, vehicle speed V, actual turning-side current value Ib, and pinion angle θp are input to the target reaction torque calculation unit 52a. The target reaction torque calculation unit 52a calculates the target reaction torque TT* based on the steering torque Th, vehicle speed V, actual turning-side current value Ib, and pinion angle θp. This target reaction torque TT* is the target control value for the steering reaction force against the steering wheel 3 generated from the steering-side motor 13. The acquired target reaction torque TT* is output to the multiplier 52b.

[0062] In the steering-side normal control unit 52, the electrical state signal Sst is input to the subtractor 52c. The subtractor 52c calculates the output gain K by subtracting the electrical state signal Sst from the "1" stored in the storage unit 52d. The obtained output gain K is output to the multiplier 52b. The output gain K is a value used to set whether the target reaction torque TT* is reflected in the steering reaction force generated from the steering-side motor 13. The storage unit 52d is a predetermined storage area of ​​a memory (not shown).

[0063] When the power status signal Sst is "0", that is, when the start switch 47 is in the open state, the output gain K is calculated as "1", which indicates that the target reaction torque TT* will be reflected in the steering reaction force generated from the steering motor 13. When the power status signal Sst is "1", that is, when the start switch 47 is in the closed state, the output gain K is calculated as "0 (zero value)", which indicates that the target reaction torque TT* will not be reflected in the steering reaction force generated from the steering motor 13. In other words, in this embodiment, when the start switch 47 is in the closed state, the target reaction torque TT* is not reflected in the steering reaction force generated from the steering motor 13.

[0064] When the output gain K is "1", that is, when the start switch 47 is in the open state, the multiplier 52b outputs the target reaction torque TT* to the adder 56 without any change, so that the target reaction torque TT* is reflected in the steering reaction force generated from the steering motor 13. When the output gain K is "0", that is, when the start switch 47 is in the closed state, the multiplier 52b outputs the zero value of the target reaction torque TT* to the adder 56, so that the target reaction torque TT* is not reflected in the steering reaction force generated from the steering motor 13.

[0065] The steering lock control unit 53 includes a target steering angle calculation unit 53a and a steering angle feedback control unit (referred to as "Steering Angle F / B Control Unit" in the figure) 53b. The electrical status signal Sst and the steering angle θs are input to the target steering angle calculation unit 53a. The target steering angle calculation unit 53a maintains the input steering angle θs when "1" is input as the electrical status signal Sst. The target steering angle calculation unit 53a calculates the maintained steering angle θs as the target steering angle θs*. The target steering angle θs* is the target control value of the steering angle θs obtained as a result of the rotation of the steering wheel 3. The obtained target steering angle θs* is output to the steering angle feedback control unit 53b.

[0066] The target steering angle θs* and the steering angle θs are input to the steering angle feedback control unit 53b. The steering angle feedback control unit 53b calculates the target angular torque Tθ* by feedback control of the steering angle θs, so that the steering angle θs conforms to the target steering angle θs*. The target angular torque Tθ* is the target control value of the steering reaction force against the steering wheel 3 generated from the steering-side motor 13. The acquired target angular torque Tθ* is output to the multiplier 53c.

[0067] In the steering lock control unit 53, the power status signal Sst is input to the multiplier 53c. When the power status signal Sst is "1", that is, when the start switch 47 is in the closed state, the multiplier 53c outputs the target angular torque Tθ* to the adder 56 without any change, so that the target angular torque Tθ* is reflected in the steering reaction force generated from the steering-side motor 13. When the power status signal Sst is "0", that is, when the start switch 47 is in the open state, the multiplier 53c outputs the zero value of the target angular torque Tθ* to the adder 56, so that the target angular torque Tθ* is not reflected in the steering reaction force generated from the steering-side motor 13.

[0068] Adder 56 calculates the target reaction torque command value Ts* by summing the target reaction torque TT* obtained by the steering-side normal control unit 52 and the target angular torque Tθ* obtained by the steering lock control unit 53. When the start switch 47 is in the open state, the target angular torque Tθ* is zero, and therefore, the target reaction torque command value Ts* is the target reaction torque TT* obtained by the steering-side normal control unit 52. On the other hand, when the start switch 47 is in the closed state, the target reaction torque TT* is zero, and therefore, the target reaction torque command value Ts* is the target angular torque Tθ* obtained by the steering lock control unit 53. The obtained target reaction torque command value Ts* is output to the power control unit 54.

[0069] The target reaction torque command value Ts*, the rotation angle θa, and the actual steering side current value Ia are input to the power control unit 54. The power control unit 54 calculates the current command value Ia* for the steering side motor 13 based on the target reaction torque command value Ts*. The power control unit 54 calculates the difference between the current command value Ia* and the current value in the dq coordinate system obtained by converting the actual steering side current value Ia obtained by the steering side current sensor 55, based on the rotation angle θa, and controls the power supply to the steering side motor 13 to eliminate the difference. Therefore, the steering side motor 13 generates a reaction force corresponding to the target reaction torque command value Ts* and rotates by the angle corresponding to the target reaction torque command value Ts*.

[0070] Turning side control unit 60

[0071] like Figure 4 As shown, the rotation angle θb and steering angle θs are input to the turning side control unit 60. The turning side control unit 60 controls the power supply to the turning side motor 32 based on the rotation angle θb and steering angle θs.

[0072] The turning-side control unit 60 includes a pinion angle calculation unit 61, a pinion angle feedback control unit (referred to as "PINION ANGLE F / B CONTROL UNIT" in the figure) 62, and a power control unit 63. The rotation angle θb is input to the pinion angle calculation unit 61. The pinion angle calculation unit 61 converts the rotation angle θb into a total angle covering a range exceeding 360 degrees, for example, by counting the number of rotations of the steering-side motor 32 from the rack neutral position, which is the position of the rack shaft 22 when the vehicle is traveling straight forward. The pinion angle calculation unit 61 calculates the pinion angle θp, which is the actual rotation angle of the pinion shaft 21, by multiplying the total angle obtained through conversion by a conversion factor based on the rotational speed ratio of the transmission mechanism 33, the lead of the conversion mechanism 34, and the rotational speed ratio of the rack and pinion mechanism 24. The obtained pinion angle θp is output to the pinion angle feedback control unit 62. The pinion angle θp is then output to the steering-side control unit 50, i.e., the steering-side general control unit 52.

[0073] The steering angle θs and pinion angle θp are input to the pinion angle feedback control unit 62. The pinion angle feedback control unit 62 calculates the turning force command value Tt* by feedback control of the pinion angle θp, so that the pinion angle θp conforms to the steering angle θs, which is the target pinion angle θp*. The acquired turning force command value Tt* is output to the power control unit 63.

[0074] The turning force command value T*, the rotation angle θb, and the actual turning side current value Ib are input to the power control unit 63. The power control unit 63 calculates the current command value Ib* for the turning side motor 32 based on the turning force command value Tt*. The power control unit 63 calculates the difference between the current command value Ib* and the current value in the dq coordinate system obtained by converting the actual turning side current value Ib detected by the turning side current sensor 64, based on the rotation angle θb, and controls the power supply to the turning side motor 32 to eliminate this difference. Therefore, the turning side motor 32 rotates by the angle corresponding to the turning force command value Tt*.

[0075] Details of control implemented according to power supply mode

[0076] like Figure 5A As shown, when the start switch 47 is in the ON state (SW: ON in the figure), power from the main power supply 46 is supplied to the steering side control unit 50 and the turning side control unit 60 via the auxiliary power supply unit 70. In this case, the auxiliary power supply 71 of the auxiliary power supply unit 70 is charged using the power supplied from the main power supply 46, and the auxiliary power supply 71 supplies power from the main power supply 46 as needed.

[0077] The steering-side control unit 50 operates using power supplied from the auxiliary power supply 71. In this case, the steering-side control unit 50 performs control using a target reaction torque command value Ts*, where the target reaction torque TT* is reflected in the target reaction torque command value Ts* because the start switch 47 is in the open state. That is, when the start switch 47 is in the open state, the steering-side control unit 50 performs energized steering-side control on the steer-by-wire system 1, such that the state of the turning unit 6 is reflected in the state of the steering unit 4, where the steering unit 4 and the turning unit 6 are separate from each other. Therefore, an appropriate responsiveness corresponding to the road reaction force can be given to the driver.

[0078] The turning-side control unit 60 operates using power supplied from the auxiliary power supply 71. In this case, because the start switch 47 is in the open state, the turning-side control unit 60 performs control for operating the turning-side motor 32. That is, when the start switch 47 is in the open state, the turning-side control unit 60 performs energized turning-side control on the steer-by-wire system 1, such that the state of the steering unit 4 is reflected in the state of the turning unit 6, wherein the steering unit 4 and the turning unit 6 are separate from each other. Therefore, when the start switch 47 is in the open state, the turning wheel 5 can be turned, thereby achieving an angle corresponding to the driver's steering operation.

[0079] like Figure 5B As shown, when the start switch 47 is in the off state (“SW: Off” in the figure), power from the main power supply 46 is cut off, and power is supplied from the auxiliary power supply unit 70 to the steering side control unit 50. Power from the auxiliary power supply unit 70 to the steering side control unit 60 is cut off. In this case, the auxiliary power supply 71 of the auxiliary power supply unit 70 serves as the power source for the steering side control unit 50. The auxiliary power supply 71 also serves as the power source for the auxiliary power control unit 72.

[0080] The steering-side control unit 50 operates using power supplied from the auxiliary power supply 71. In this case, since the start switch 47 is in the closed state, the steering-side control unit 50 performs control using a target reaction torque command value Ts* that reflects the target angular torque Tθ*. That is, the steering-side control unit 50 performs power-off steering-side control on the steer-by-wire system 1, suppressing the difference between the states of the separate turning unit 6 and the steering unit 4 when the start switch 47 is in the closed state. In this embodiment, the torque of the steering-side motor 13 is used to perform a locking control to suppress the rotation of the steering wheel 3 as power-off steering-side control. That is, in this embodiment, the steering-side motor 13 is an example of a rotation suppression unit.

[0081] For example, such as Figure 6As shown in part (a), the period during which the start switch 47 is in the closed state, that is, the period from when the start switch 47 has switched from the open state ("open" in the figure) to the closed state ("closed" in the figure) until the start switch 47 switches to the open state again, is the first power-off period t0.

[0082] In this case, such as Figure 6 As shown in section (b), locking control of the steering-side control unit 50 is continuously performed during the operation period tl, which coincides with the entire first power-off period t0. Therefore, even when the start switch 47 is in the off state and the driver intends to steer the steering wheel, the torque of the steering-side motor 13 can be used to prevent rotation of the steering wheel 3, i.e., to lock the steering wheel 3. Even when the steering wheel 3 rotates while the start switch 47 is in the off state, the torque of the steering-side motor 13 can be used to return the position of the steering wheel 3 to the position when the start switch 47 is switched off relative to the target steering angle θs*.

[0083] The power supply to the turning control unit 60 from both the main power supply 46 and the auxiliary power supply 71 is cut off, and the turning control unit 60 cannot operate. In this situation, since the start switch 47 is in the closed state, the turning control unit 60 ceases control for operating the turning motor 32. That is, when the start switch 47 is in the closed state, the turning control unit 60 cannot reflect the state of the steering unit 4 in the state of the turning unit 6 when the steering unit 4 and the turning unit 6 are separated. Therefore, even if the driver performs a steering operation when the start switch 47 is in the closed state, the turning wheels 5 cannot be turned to achieve the angle corresponding to the steering operation.

[0084] According to the operation of the first embodiment

[0085] According to this implementation method, in Figure 6 In the operation period tl shown in section (b), the power required for the operation of the steering-side motor 13 is supplied from the auxiliary power supply 71, during which power from the main power supply 46 is cut off and the start switch 47 is in the off state. That is, during operation period t1, even when the steering-side motor 13 is operated to suppress the rotation of the steering wheel 3, power is not required from the main power supply 46. Therefore, in Figure 6 As shown in part (a) and during the first power-off period t0 when the start switch 47 is in the off state, the power consumption in the main power supply 46 can be reduced even when the steering side motor 13 is operating.

[0086] Advantages of the first embodiment

[0087] (1-1) In this embodiment, since the power required for the operation of the steering motor 13 is supplied from the auxiliary power supply 71 during operation period tl, the power consumption in the main power supply 46 can be reduced even when the steering motor 13 is operating. In this case, when the start switch 47 is in the off state, the power required for the operation of the steering motor 13 can be adequately ensured so that the main power supply 46 can supply power normally when the start switch 47 is switched to the on state next time.

[0088] (1-2) Since the operation period tl is set to be consistent with the entire first power-off period t0, the angle difference between the steering wheel 3 and the turning wheel 5 can be appropriately suppressed.

[0089] (1-3) In this embodiment, the steering-side motor 13 is used as a rotation suppression unit to suppress the rotation of the steering wheel 3. In this case, even during the first power-off period t0, power needs to be supplied to the steering actuator 12 so that the steering actuator 12 can operate during the operation period t1.

[0090] In this respect, in this embodiment, even during the first power outage period t0, power can be supplied to the steering actuator 12 while the load on the main power supply 46 is suppressed. Therefore, even when the steering-side motor 13 is used as the rotation suppression unit, the power required for the operation of the steering-side motor 13 can be adequately ensured so that the main power supply 46 can supply power normally when the start switch 47 is switched to the on state again. In this case, it is not necessary to use a relatively low-power mechanical structure as the rotation suppression unit. This is effective for reducing the size of the steering system 1—especially the steering actuator 12—simplifying its configuration, and reducing manufacturing costs.

[0091] (1-4) In this embodiment, the auxiliary power supply 71 serves as a second power supply. In this case, when the power supply required for the operation of the steering-side motor 13 when the start switch 47 is in the off state is achieved, the degree of modification required to add the configuration of the second power supply to the steering system 1 can be reduced.

[0092] Second Implementation Method

[0093] The steering system according to the second embodiment will now be described with reference to the accompanying drawings. The main differences from the first embodiment will be described. Elements identical to those in the first embodiment will be referred to by the same reference numerals, etc., and their descriptions will not be repeated.

[0094] like Figure 1As shown by the alternating long and two short dashed lines, the vehicle control unit 80 is connected to the steering control unit 2 via the vehicle network 45. In this embodiment, the key authentication device 81, the door lock device 82, and the seat belt device 83 are configured as the vehicle control unit 80. The key authentication device 81, the door lock device 82, and the seat belt device 83 are separately located in the vehicle from the steering control unit 2.

[0095] Key authentication device 81

[0096] The key authentication device 81 allows vehicle use based on key information. This key information is, for example, information stored in a vehicle key KE carried by the driver, such as a remote key or smartphone. The key authentication device 81 performs radio communication with the vehicle key KE, enabling the door DR to lock and unlock, and the start switch 47 to operate, thus allowing vehicle use, provided radio communication has been established. The coverage range of the radio communication is typically a relatively short predetermined range, for example, 1 meter from the vehicle. The key authentication device 81 generates a key position signal Ske based on whether radio communication with the vehicle key KE has been established. This key position signal Ske indicates the key position of the vehicle key KE relative to the vehicle. When radio communication with the vehicle key KE has been established, the key authentication device 81 generates a key position signal Ske of value "1," indicating that the driver is within a predetermined distance from the vehicle. In this case, a high probability can be determined that the driver may be getting into or out of the vehicle as a state of getting in or out of the vehicle relative to the vehicle, and it is assumed that there is a high probability that the driver may be touching the steering wheel 3. When radio communication with the vehicle key KE has not yet been established, the key authentication device 81 generates a key position signal Ske as "0 (zero value)". This "0 (zero value)" indicates that the driver is not within a predetermined distance from the vehicle, that is, the driver is far from the vehicle. In this case, it can be determined that there is a low probability that the driver is getting on or off the vehicle as a state of getting on or off the vehicle relative to the vehicle, and it is assumed that there is a low probability that the driver may touch the steering wheel 3. The acquired key position signal Ske is output to the steering control device 2, i.e., the auxiliary power supply device 70, via the vehicle network 45.

[0097] Door lock device 82

[0098] The door lock device 82 controls the switching between locking and unlocking of the door DR. The door lock device 82 generates a door lock signal Sdl, which indicates the locking or unlocking state of the door DR. When the door DR is unlocked, the door lock device 82 generates a door lock signal Sdl of value "1", indicating that the door DR is unlocked. In this case, when the probability of the driver getting on or off the vehicle (i.e., the probability that the driver may get on or off the vehicle) is high, based on the key position signal Ske, there is a high probability that the driver may touch the steering wheel 3. When the door DR is locked, the door lock device 82 generates a door lock signal Sdl of value "0 (zero value)", indicating that the door DR is locked. In this case, when the probability of the driver getting on or off the vehicle is low, there is a low probability that the driver may touch the steering wheel 3. The acquired door lock signal Sdl is output to the steering control device 2, i.e., the auxiliary power supply device 70, via the vehicle network 45.

[0099] Seat belt device 83

[0100] The seatbelt device 83 detects seat load, which indicates the load on passenger seats other than the driver's seat and on the rear seats. For example, the seat load is detected using a load sensor Ps of the seatbelt device 83. The seatbelt device 83 generates a seat status signal Ssb based on the seat load. This seat status signal Ssb indicates the presence of an occupant other than the driver in at least one of the passenger seats and the rear seats. When a seat load with a value within a predetermined range used to determine the presence of an occupant in at least one of the passenger seats and the rear seats is detected, the seatbelt device 83 generates a seat status signal Ssb of "1," which indicates the presence of an occupant in at least one seat. In this case, since the occupant is present in the passenger compartment, there is a high probability that the occupant may come into contact with the steering wheel 3. When a seat load with a value within a predetermined range used to determine the absence of an occupant in the passenger seats and the rear seats is detected, the seatbelt device 83 generates a seat status signal Ssb of "0 (zero value)," which indicates that the occupant is not present in the seat. In this situation, when the key position signal Ske determines that the probability of the driver getting on or off the vehicle relative to the vehicle is low, there is a low probability that the driver may touch the steering wheel 3. The acquired seat status signal Ssb is output to the steering control device 2, i.e., the auxiliary power device 70, via the vehicle network 45.

[0101] Auxiliary power supply unit 70

[0102] like Figure 7 As shown, the key position signal Ske, the door lock signal Sdl, and the seat status signal Ssb are input to the auxiliary power control unit 73 of the auxiliary power device 70 according to this embodiment. The auxiliary power control unit 73 generates a power status signal Sst based on the key position signal Ske, the door lock signal Sdl, the seat status signal Ssb, and the open or closed state of the start switch 47.

[0103] Specifically, the auxiliary power control unit 73 includes a state determination unit 73a. A key position signal Ske, a door lock signal Sdl, and a seat status signal Ssb are input to the state determination unit 73a. The state determination unit 73a calculates the occupant state gain G based on the key position signal Ske, the door lock signal Sdl, and the seat status signal Ssb. The occupant state gain G is an indicator of the likelihood of the driver or occupant touching the steering wheel 3, and is calculated as "1" when there is a high likelihood of the driver or occupant touching the steering wheel 3, and as "0" (zero value) when there is a low likelihood. An example of an auxiliary power control unit 73 including the state determination unit 73a is an electronic control unit including a processor.

[0104] For example, when at least one of the key position signal Ske, door lock signal Sdl, and seat status signal Ssb is "1", the occupant state gain G is calculated as "1", which is a value indicating a high probability that the driver or occupant may have contact with the steering wheel 3. When all of the key position signal Ske, door lock signal Sdl, and seat status signal Ssb are "0", the occupant state gain G is calculated as "0", which is a value indicating a low probability that the driver or occupant may have contact with the steering wheel 3.

[0105] The auxiliary power control unit 73 generates a power status signal Sst based on the occupant status gain G. Specifically, when the start switch 47 is in the on state, regardless of the value of the occupant status gain G, the auxiliary power control unit 73 generates a "0" as the power status signal Sst and outputs the generated power status signal Sst to the steering-side control unit 50. In this case, the auxiliary power control unit 73 performs control to supply power to the steering-side control unit 50 from at least one of the main power supply 46 and the auxiliary power supply 71.

[0106] When the start switch 47 is in the off state and the occupant status gain G is "1", the auxiliary power control unit 73 generates "1" as a power status signal Sst and outputs the generated power status signal Sst to the steering side control unit 50. In this case, the auxiliary power control unit 73 performs control to supply power from the auxiliary power supply 71 to the steering side control unit 50, and performs control to cut off the power supply to the turning side control unit 60.

[0107] When the start switch 47 is in the off state and the occupant status gain G is "0", the auxiliary power control unit 73 generates "0" as the power status signal Sst and outputs the generated power status signal Sst to the steering side control unit 50. In this case, the auxiliary power control unit 73 performs control to cut off the power supply to the steering side control unit 50 and the cornering side control unit 60.

[0108] Power supply mode of power system D

[0109] like Figure 8 As shown, the power system D according to this embodiment determines the power supply mode based on the on or off state of the start switch 47 (“SW”, “on” or “off” in the figure) and the value of the occupant state gain G. The power supply mode is a mode that supplies power to the auxiliary power control unit 72, the steering side control unit 50 and the turning side control unit 60.

[0110] When the start switch 47 is in the ON position, the power system D performs control to supply power to all control units 50, 60, and 72, regardless of the value of the occupant state gain G. This is the same as in the first embodiment.

[0111] When the start switch 47 is in the off state and the occupant state gain G is "1", the power system D performs control to supply power to the auxiliary power control unit 72 and the steering side control unit 50, and performs control to cut off the power supply to the turning side control unit 60. In this case, power is supplied from the auxiliary power source 71 to the auxiliary power control unit 72 and the steering side control unit 50. In this embodiment, when the power supply from the main power source 46 is cut off and there is a high probability that the driver or occupant may come into contact with the steering wheel 3, the auxiliary power control unit 72 and the steering side control unit 50 use the auxiliary power source 71 to ensure the power required for their operation. That is, when the start switch 47 is in the off state and there is a high probability that the driver or occupant may come into contact with the steering wheel 3, power from the auxiliary power source 71 is supplied to the steering actuator 12.

[0112] When the start switch 47 is in the off state and the occupant state gain G is "0", the power system D performs control to supply power to the auxiliary power control unit 72, and performs control to cut off the power supply to the steering side control unit 50 and the turning side control unit 60. In this case, power from the auxiliary power source 71 is supplied to the auxiliary power control unit 72. In this embodiment, when the power supply from the main power source 46 is cut off, the auxiliary power control unit 72 uses the auxiliary power source 71 to ensure the power required for its operation. On the other hand, when the power supply from the main power source 46 is cut off and there is a low probability that the driver or occupant may touch the steering wheel 3, the steering side control unit 50 does not obtain the power required for its operation from the auxiliary power source 71. That is, when the start switch 47 is in the off state and there is a low probability that the driver or occupant may touch the steering wheel 3, the power supply from the auxiliary power source 71 to the steering actuator 12 is cut off.

[0113] Details of control implemented according to power supply mode

[0114] like Figure 9A As shown, when the start switch 47 is in the off state and the occupant state gain G is "0" ("SW: Off + No Occupant" in the figure), the power supply from the main power supply 46 and the auxiliary power supply unit 70 to the steering side control unit 50 and the turning side control unit 60 is cut off. In this case, the power supply from both the main power supply 46 and the auxiliary power supply 71 is cut off, and therefore the steering side control unit 50 and the turning side control unit 60 cannot operate. When the start switch 47 is in the off state and the occupant state gain G is "0", the probability that the driver or occupant may come into contact with the steering wheel 3 is low, and therefore, although the start switch 47 is in the off state, there is a low probability that the states of the separate steering unit 4 and the turning unit 6 may become different from each other.

[0115] like Figure 9B As shown, when the start switch 47 is in the off state and the occupant state gain G is "1" ("SW: Off + Occupant" in the figure), the power supply from the main power supply 46 is cut off, and power from the auxiliary power supply unit 70 is supplied to the steering side control unit 50. The power supply from the auxiliary power supply unit 70 to the steering side control unit 60 is cut off. In this case, the auxiliary power supply 71 of the auxiliary power supply unit 70 is used as the power source for the steering side control unit 50. The auxiliary power supply 71 also serves as the power source for the auxiliary power control unit 72.

[0116] The steering-side control unit 50 operates using power supplied from the auxiliary power supply 71. In this case, since the start switch 47 is in the off state, i.e., the power status signal Sst is "1", the steering-side control unit 50 uses the target reaction torque command value Ts*, which reflects the target angular torque Tθ*, to perform control. That is, the steering-side control unit 50 performs lock-up control.

[0117] For example, such as Figure 10 As shown in parts (a) and (b), the occupant state gain G remains at "1" ("Occupant: Yes" in the figure) during the period after the start of the first power-off period t0 when there is a high probability that the driver or occupant may touch the steering wheel 3. Thereafter, when the probability that the driver or occupant may touch the steering wheel 3 decreases, the occupant state gain G becomes "0" ("Occupant: No" in the figure).

[0118] In this case, such as Figure 10 As shown in part (c), during the operation periods t2a and t2b in which the occupant state gain G is “1” (“Occupant: Yes” in the figure) during the first power-off period t0, the locking control of the steering side control unit 50 is continuously executed.

[0119] Specifically, during operation period t2a, following the first power-off period t0 which begins when the driver disconnects the start switch 47 upon exiting the vehicle, the locking control begins operation. Subsequently, when the driver is separated from the vehicle by a predetermined distance, the locking control terminates its operation, and operation period t2a ends. Thereafter, during operation period t2b, when the driver approaches the vehicle during the first power-off period t0 to be within a predetermined distance of the vehicle, the locking control begins operation. Subsequently, when the first power-off period t0 ends when the driver reconnects the start switch 47 upon entering the vehicle, the locking control terminates its operation, and operation period t2b ends.

[0120] Advantages of the second implementation method

[0121] (2-1) In this embodiment, when the driver leaves the vehicle and the probability of the driver possibly touching the steering wheel 3 is high, the steering-side motor 13 can be operated to suppress the rotation of the steering wheel 3. In this case, the period during which the steering-side motor 13 operates can be set to be shorter than the first power-off period t0. This is effective in suppressing power consumption in the auxiliary power supply 71.

[0122] (2-2) Based on the key position, the driver's entry / exit status relative to the vehicle can be determined, as well as the likelihood of the driver contacting the steering wheel 3. Based on the key position and the locking status of the door DR, the driver's entry / exit status relative to the vehicle can be determined more accurately, and the likelihood of the driver contacting the steering wheel 3 can be determined more accurately. Therefore, the status determination unit 73a can appropriately determine the driver's status indicating whether the driver is leaving or approaching the vehicle.

[0123] (2-3) Regarding the key position and the locking status of the door DR, even when the locking status of the door DR is replaced with the open-closed status of the door DR (i.e., the open-closed status indicating the open or closed status of the door DR), the probability of the driver contacting the steering wheel 3 can be determined more accurately. In this case, the door lock device 82 can detect the open-closed status of the door DR of the driver's seat.

[0124] like Figure 7 As shown by the alternating long and two short dashed lines, a door open-close signal Sds, which indicates whether the driver's seat door DR is open, can be input to the state determination unit 73a instead of the door lock signal Sd1. For example, the door lock device 82 generates a door open-close signal Sds, which indicates whether the driver's seat door DR is open, instead of the door lock signal Sd1. In this case, when the driver's seat door DR is open, the door lock device 82 generates a door open-close signal Sds of value "1". When the driver's seat door DR is closed, the door lock device 82 generates a door open-close signal Sds of value "0 (zero value)". The acquired door open-close signal Sds is output to the steering control device 2, i.e., the auxiliary power supply device 70, via the vehicle network 45.

[0125] (2-4) In this embodiment, since the state of occupants other than the driver is also considered, the possibility of occupants other than the driver coming into contact with the steering wheel 3 can be considered. (2-5) As by Figure 1 As shown by the alternating long and two short dashed lines, even a configuration that utilizes a passenger compartment camera (CM) installed in the passenger compartment to detect the status of occupants other than the driver can consider the possibility of contact between occupants other than the driver and the steering wheel 3. For example, a passenger compartment monitoring device 84 can be installed as a vehicle control device 80. The passenger compartment monitoring device 84 is installed separately from the steering control device 2 in the vehicle. The passenger compartment monitoring device 84 monitors the status of the passenger compartment to prevent vehicle theft or record the situation near the vehicle. The status of the passenger compartment is detected by the passenger compartment camera (CM) of the passenger compartment monitoring device 84. The passenger compartment monitoring device 84 can detect the presence of occupants other than the driver in the passenger seats and rear seats based on the passenger compartment camera (CM).

[0126] As by Figure 7 As shown by the alternating long and two short dashed lines, the passenger compartment monitoring signal Ssc, which indicates the status of occupants other than the driver, can be input to the status determination unit 73a instead of the seat status signal Ssb. For example, the passenger compartment monitoring device 84 generates the passenger compartment monitoring signal Ssc, which indicates the status of occupants other than the driver. In this case, when there is an occupant other than the driver in the passenger compartment, the passenger compartment monitoring device 84 generates a passenger compartment monitoring signal Ssc of "1". When there is no occupant other than the driver in the passenger compartment, the passenger compartment monitoring device 84 generates a passenger compartment monitoring signal Ssc of "0 (zero value)". The acquired passenger compartment monitoring signal Ssc is output to the steering control device 2, i.e., the auxiliary power supply device 70, via the vehicle network 45.

[0127] Other implementation methods

[0128] The aforementioned implementation method can be modified as follows. Unless there is a technical conflict, other implementation methods can be combined.

[0129] In the second embodiment, the state determination unit 73a may disregard the state of occupants other than the driver. In this case, the seat state signal Ssb may not be input to the state determination unit 73a. Even when the seat state signal Ssb is input to the state determination unit 73a, the seat state signal Ssb may not be used to generate the occupant state gain G. This also applies to the passenger compartment monitoring signal Ssc.

[0130] In the second embodiment, the state determination unit 73a can calculate the occupant state gain G using at least the key position signal Ske. In this case, the door lock signal Sdl and the seat state signal Ssb may not be used in the state determination unit 73a. Both the door lock signal Sdl and the door open-close signal Sds may be used in the state determination unit 73a. Both the seat state signal Ssb and the passenger compartment monitoring signal Ssc may be used in the state determination unit 73a.

[0131] In the second embodiment, the auxiliary power control unit 73 may not output the power status signal Sst when the occupant status gain G is “0” and the start switch 47 is in the off state.

[0132] In the second embodiment, the function of the state determination unit 73a can be implemented as the function of the steering side control unit 50 or the turning side control unit 60, that is, the function of the steering control device 2. In this case, the steering system 1 can be configured to be powered from the power line L1, regardless of whether the start switch 47 is on or off. During operation periods t2a and t2b, the power required for the operation of the steering side motor 13 is supplied from the auxiliary power supply 71.

[0133] In the aforementioned embodiment, the auxiliary power control unit 72 can be configured to supply power from the power line L1 regardless of whether the start switch 47 is on or off. In this case, the auxiliary power control unit 72 can charge the auxiliary power supply 71 even when the start switch 47 is off.

[0134] In the aforementioned embodiment, even when the start switch 47 is in the off state, locking control can be performed according to the scheduling date and time indicated to the driver for use of the vehicle's schedule. That is, even when the start switch 47 is in the off state, operation period t1 or operation period t2b can begin according to the scheduling date and time. For example, the driver can set the scheduling date and time for the vehicle or steering system 1 using an application such as a navigation system or smartphone. In this case, the auxiliary power control unit 72 is configured to perform control such that even when the start switch 47 is in the off state, power is supplied from the auxiliary power supply 71 to the steering side control unit 50 according to the scheduling date and time, which can be identified using a function such as a real-time clock. The steering side control unit 50 can be configured to autonomously perform locking control according to the scheduling date and time, which can be identified using a function such as a real-time clock, even when the start switch 47 is in the off state. In the second embodiment, when the start switch 47 is in the off state, locking control can be performed according to the scheduling date and time, regardless of the value of the occupant state gain G.

[0135] In the aforementioned embodiment, the steering lock control unit 53 can achieve phase-short circuit-based locking control by short-circuiting the connection line between the steering side control unit 50 and the phase motor coil of the steering side motor 13. In this case, the turning side control unit 60 can be configured to supply power from the auxiliary power supply 71 when the start switch 47 is in the off state. For example, with phase-short circuit-based locking control, there is a possibility that the steering wheel 3 may rotate due to the application of a force greater than expected. In this case, if the turning side control unit 60 can operate even when the start switch 47 is in the off state, the steering wheel 5 can turn by an amount corresponding to the rotation of the steering wheel 3. In this case, the angle difference between the angle of the steering wheel 3 and the angle of the steering wheel 5 can be appropriately suppressed.

[0136] In the foregoing embodiments, the steering lock control unit 53 can implement lock control based on so-called damping control for controlling steering speed, which is the rate of change of steering angle θs. For example, the steering lock control unit 53 can perform damping control as lock control, for example, by setting a target steering speed to zero.

[0137] In the aforementioned embodiments, a dedicated power supply separate from the auxiliary power supply 71 can be set as a second power supply that supplies power to the steering control unit 50, i.e., the steering motor 13, when the start switch 47 is in the off state.

[0138] In the aforementioned embodiment, a mechanical configuration can be used as a rotation suppression unit to suppress the rotation of the steering wheel 3. In this case, switching to the state where the rotation of the steering wheel 3 is suppressed or maintaining the state where the rotation of the steering wheel 3 is suppressed requires electricity, but the power consumption in the main power supply 46 can be suppressed.

[0139] In the aforementioned embodiments, double-layer capacitors or secondary batteries can be used instead of lithium-ion capacitors for the auxiliary power supply 71. In the aforementioned embodiments, in addition to supplying backup power to control units 50 and 60 in place of the main power supply 46, the auxiliary power supply device 70 can also be configured to operate to step up the power supplied from the main power supply 46.

[0140] In the foregoing embodiments, each of the auxiliary power control units 72 and 73 can be configured to communicate with the steering side control unit 60 via a dedicated signal line. The power status signal Sst can be input to the steering side control unit 50 via the steering side control unit 60. In this case, each of the auxiliary power control units 72 and 73 may not be configured to communicate with the steering side control unit 50 via a dedicated signal line. This is effective when the location of the auxiliary power supply unit 70 is set closer to the steering unit 6 between the steering unit 4 and the steering unit 6 in the steering system 1.

[0141] In the aforementioned embodiments, a control unit with the following functions can be provided in the steering control device 2, which integrates the functions of the steering side control unit 50 for operating the steering side motor 13 and the turning side control unit 60 for operating the turning side motor 32.

[0142] In the aforementioned embodiment, the target reaction torque calculation unit 52a may use at least a state variable that varies according to the operating state of the steering wheel 3 when calculating the target reaction torque TT*. In this case, the target reaction torque calculation unit 52a may not use the vehicle speed V or the steering torque Th, or it may combine the vehicle speed V and / or the steering torque Th with another factor.

[0143] In the aforementioned embodiment, the steering side control unit 50 can calculate the value calculated by executing torque feedback control as the target reaction torque TT*, which is used to make the steering torque Th conform to the target steering torque calculated based on the steering torque Th.

[0144] In the aforementioned embodiment, the steering angle calculation unit 51 can calculate the steering angle θs by taking into account the torsion of the steering shaft 11 based on the steering torque Th and adding the torsion to the rotation angle θa or subtracting the torsion from the rotation angle θa.

[0145] In the aforementioned embodiment, the detection result from the steering sensor disposed in the steering shaft 11 to detect the rotation angle of the steering shaft 11 can be used as the steering angle θs.

[0146] In the foregoing embodiments, a configuration in which the turning-side motor 32 is arranged coaxially with the rack shaft 22 can be adopted, or a configuration in which the turning-side motor 32 is connected to the pinion shaft via a worm and a worm wheel, wherein the pinion shaft and the rack shaft 22 together constitute a rack and pinion mechanism.

[0147] In the foregoing embodiments, the steering control device 2 can be configured as a processing circuit comprising (1) one or more processors operating according to a computer program (software), (2) one or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), that perform at least some of the various processes, or (3) a combination thereof. The processor includes a CPU and memory, such as RAM and ROM, and the memory stores program code or commands configured to cause the CPU to perform the processes. Memory, i.e., non-transitory computer-readable media, includes all available media accessible by a general-purpose or special-purpose computer.

[0148] In the foregoing embodiments, the turning unit 6 of the steering system 1 may have an independent turning structure, in which the left and right turning wheels 5 can turn independently. Technical concepts that can be understood from the foregoing and other embodiments can be added below.

[0149] (A) The state determination unit can be configured to determine the driver's state by also considering the state of occupants other than the driver. For example, during the first power outage period, when the driver is away from the vehicle but the occupants remain in the passenger compartment, there is a possibility that an occupant other than the driver remaining in the passenger compartment may come into contact with the steering wheel. In this respect, with this configuration, since the state of occupants other than the driver is also taken into consideration, the possibility of an occupant other than the driver coming into contact with the steering wheel can be considered.

[0150] (B) The state determination unit can be configured to determine the state of the occupants other than the driver based on at least one of the following: i) the seat state of the seat other than the driver's seat where the driver is seated; and ii) the detection state of the detection device installed in the carriage to detect the presence of the occupants.

Claims

1. A steering system characterized by, includes: a steering actuator (12) configured to operate using electric power supplied from a first power supply installed in a vehicle, such that a steering reaction force is applied to a steering wheel (3) of the vehicle; and a turn actuator (31) having a structure in which a power transmission path between the turn actuator (31) and the steering actuator (12) is cut off, the turn actuator (31) being configured to operate using electric power supplied from the first power supply, such that a turn wheel of the vehicle turns, wherein the steering system is configured such that, in a case where a power state of the vehicle is an on state, electric power is supplied from the first power supply to the steering actuator (12) and the turn actuator (31), and in a case where the power state is an off state, the supply of electric power from the first power supply is cut off, and wherein the steering system further includes: a rotation suppression unit configured to operate such that, in at least a portion of a first power-off period from when the power state changes to the off state until the power state next changes to the on state, rotation of the steering wheel (3) is suppressed, a second power supply configured to supply electric power required for operation of the rotation suppression unit in the operation period, the second power supply being different from the first power supply. The operation period coincides with the first power-off period with respect to a state of the vehicle.

2. The steering system of claim 1, wherein, 3. The steering system according to claim 1, characterized in that: with respect to a state of a driver and a state of the vehicle, the operation period is a period in which the driver is located within a predetermined distance from the vehicle in the first power-off period; and the rotation suppression unit is configured to operate in a period in which the driver is within a predetermined distance from the vehicle as the operation period in a case where the power state is the off state. further includes an electronic control unit configured to determine a state of the driver, 4. The steering system of claim 3, wherein, wherein the electronic control unit is configured to determine the state of the driver based on at least one of i) a key position of a vehicle key for allowing use of the vehicle with respect to the vehicle, ii) the key position and a lock state of a door of the vehicle that is opened and closed when the driver gets on the vehicle and when the driver gets off the vehicle, and iii) the key position and an open-close state of the door.

5. The steering system according to claim 1, characterized in that: the steering actuator (12) includes a reaction force motor configured to generate a motor torque that serves as a power to apply the steering reaction force to the steering wheel (3), and the rotation suppression unit is the reaction force motor. the second power supply is configured to supply electric power to the steering actuator (12) and the turn actuator (31) as a backup instead of the first power supply, in a condition in which electric power supplied by the first power supply is reduced or cut off when the power state is the on state.

6. The steering system according to any one of claims 1 to 5, characterized in that, ​

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