JP2017001611A - Steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to achieve cost down while maintaining control performance.SOLUTION: A steering control device comprises: a connection changeover part 6 which performs changeover between connection and disconnection of first and second steering shafts 3, 4; a torsion bar 13 as a part of the second steering shaft 4; a first rotation angle sensor 22 for detecting a rotation angle of an input shaft 11 which is connected to one end of the torsion bar 13; and a second rotation angle sensor 23 for detecting a rotation angle of an output shaft 12 which is connected to the other end of the torsion bar 13. In the state that the connection change part 6 is disconnected, steering controllers 35, 37 control steering motors 31, 36 on the basis of at least one detection result of the first rotation angle sensor 22 and the second rotation angle sensor 23, thereby performing steer-by-wire control. In the state that the connection changeover part 6 is connected, the controllers control the steering motors 31, 36 on the basis of a torsional amount of the torsion bar 13 which is calculated a difference in the rotation angles detected by the first rotation angle sensor 22 and the second rotation angle sensor 23 thereby performing assist control.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steering control device.

  Patent Document 1 discloses a steering control having a steer-by-wire structure that drives and controls a first steering motor and a second steering motor according to a steering command value and drives and controls a reaction force motor according to a reaction force command value. An apparatus is disclosed.

  The steering control device disclosed in Patent Document 1 mechanically connects the steering system by connecting a clutch when an abnormality occurs in the control system of the second steering controller that controls the driving of the second steering motor. Then, assist control by the first turning motor is executed to reduce the operation burden on the driver.

JP 2014-156151 A

  The steering control device described in Patent Literature 1 performs steer-by-wire control and assist control. During steer-by-wire control, the steering motor is controlled based on a signal from a resolver provided in the steering angle sensor and the steering motor, and during assist control, the steering motor is controlled based on a signal from a torque sensor.

  As described above, in the steering control device described in Patent Document 1, since steer-by-wire control and assist control are performed, many sensors are necessary for steering control, which causes an increase in cost of the steering control device.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce costs while maintaining control performance in a steering control device having a steer-by-wire structure.

  The present invention includes a connection switching unit that switches connection and disconnection between the first steering shaft and the second steering shaft, a steering motor that applies a steering force to the rack shaft in a state where the connection switching unit is disconnected, A torsion bar that is provided as part of the steering shaft and torsionally deforms when the steering operation is performed with the connection switching portion connected, and an input that is provided as part of the second steering shaft and connected to one end of the torsion bar A first rotation angle sensor for detecting the rotation angle of the shaft, a second rotation angle sensor for detecting the rotation angle of the output shaft provided as a part of the second steering shaft and connected to the other end of the torsion bar, and steering A steering controller that controls driving of the motor, and the steering controller includes a first steering controller in a state in which the connection switching unit is disconnected. The steer-by-wire control is performed by controlling the steered motor based on the detection result of at least one of the turn angle sensor and the second rotation angle sensor and the rudder angle sensor, and the first rotation is performed when the connection switching unit is connected. Assist control is performed to assist the steering operation by the driver by controlling the turning motor based on the torsion bar twist amount calculated from the difference between the rotation angles detected by the angle sensor and the second rotation angle sensor. And

  In the present invention, the first rotation angle sensor and the second rotation angle sensor provided on each of the input shaft and the output shaft connected to the torsion bar are used in both the steer-by-wire control and the assist control. Therefore, the number of sensors necessary for steering control can be reduced.

  According to the present invention, in a steering control device having a steer-by-wire structure, costs can be reduced while maintaining control performance.

It is a lineblock diagram of a steering control device concerning an embodiment of the present invention.

  Hereinafter, a steering control device 100 according to an embodiment of the present invention will be described with reference to FIG.

  The steering control device 100 assists steer-by-wire control in which the wheel 2 is steered in accordance with the operation state of the steering wheel 1 by the driver and the operation of the steering wheel 1 by the driver (hereinafter referred to as “steering operation”). Both the assist control and the assist control are possible.

  The steering control device 100 includes a first steering shaft 3 that rotates in response to a steering operation by a driver, a second steering shaft 4 that is connected to a rack shaft 5 that steers the wheel 2, a first steering shaft 3, and a first steering shaft 3. 2 and a clutch 6 as a connection switching unit for switching between connection and disconnection with the steering shaft 4.

  The clutch 6 is an electromagnetic clutch, which cuts the first steering shaft 3 and the second steering shaft 4 when the electromagnetic coil is excited, and mechanically connects the first steering shaft 3 and the second steering shaft 4 when the electromagnetic coil is not excited. Connect to. Steer-by-wire control is performed when the clutch 6 is disconnected, and assist control is performed when the clutch 6 is connected.

  The second steering shaft 4 includes an input shaft 11 connected to the clutch 6, a first pinion shaft 12 as an output shaft on which a pinion gear 12 a meshing with a rack gear 5 a formed on the rack shaft 5 is formed, And a torsion bar 13 for connecting the first pinion shaft 12.

  When the steering wheel 1 is operated with the clutch 6 connected, the first steering shaft 3 and the second steering shaft 4 rotate, and the rotation is converted into linear motion by the pinion gear 12a and the rack gear 5a, and the knuckle arm The wheel 2 is steered via 14.

  The steering control device 100 includes a second pinion shaft 16 in addition to the first pinion shaft 12. The second pinion shaft 16 has a second pinion gear 16 a that meshes with a rack gear 5 a formed on the rack shaft 5. Thus, the steering control device 100 is a dual pinion type having two pinion shafts.

  The first steering shaft 3 is provided with a steering angle sensor 21 that detects a steering angle that is a rotation angle of the steering wheel 1. Although not shown, the rudder angle sensor 21 includes a center gear that rotates integrally with the first steering shaft 3 and two outer gears that mesh with the center gear, and is based on a change in magnetic flux accompanying the rotation of the two outer gears. Thus, the rotation angle of the center gear, that is, the rotation angle of the first steering shaft 3 is calculated. Thus, the rudder angle sensor 21 can detect the absolute rotation angle of the first steering shaft 3.

  The input shaft 11 is provided with a first rotation angle sensor 22 that detects the rotation angle of the input shaft 11. The first pinion shaft 12 is provided with a second rotation angle sensor 23 that detects the rotation angle of the first pinion shaft 12. Thus, the first rotation angle sensor 22 is provided on the input shaft 11 connected to one end of the torsion bar 13, and the second rotation angle sensor is provided on the first pinion shaft 12 connected to the other end of the torsion bar 13. 23 is provided. The first rotation angle sensor 22 and the second rotation angle sensor 23 have the same configuration as the steering angle sensor 21 described above, and can detect the absolute rotation angles of the input shaft 11 and the first pinion shaft 12, respectively. it can.

  The steering control device 100 includes a first steering motor 31 and a second steering motor 36 that apply a steering force to the rack shaft 5 in a state in which the clutch 6 is disconnected, and a first steering in a state in which the clutch 6 is disconnected. A reaction force motor 41 that applies a steering reaction force to the shaft 3, a first turning controller 35 that controls the driving of the first turning motor 31, and a second turning controller that controls the driving of the second turning motor 36. 37 and a reaction force controller 45 that controls the driving of the reaction force motor 41. The first turning controller 35, the second turning controller 37, and the reaction force controller 45 are connected to each other via a communication line 50 so that they can communicate with each other. In addition to the detection signals of the steering angle sensor 21, the first rotation angle sensor 22, and the second rotation angle sensor 23, vehicle state information such as the vehicle speed is input to the first steering controller 35 and the second steering controller 37. Is done. In addition to the detection signal of the steering angle sensor 21, vehicle state information such as the vehicle speed is input to the reaction force controller 45.

  The driving force of the first turning motor 31 is output to the first pinion shaft 12 with the rotational speed reduced by the speed reduction mechanism 32. Therefore, when the first turning motor 31 is driven in a state where the clutch 6 is disconnected, a turning force for turning the wheels 2 is applied to the rack shaft 5 through the first pinion shaft 12. Further, when the first turning motor 31 is driven in a state where the clutch 6 is connected, an assist force that assists the steering operation by the driver is applied to the first pinion shaft 12. The speed reduction mechanism 32 includes a worm shaft 32 a connected to the output shaft of the first turning motor 31, and a worm wheel 32 b that meshes with the worm shaft 32 a and is connected to the first pinion shaft 12.

  The driving force of the second turning motor 36 is output to the second pinion shaft 16 with the rotational speed reduced by the speed reduction mechanism 38. Therefore, when the second turning motor 36 is driven with the clutch 6 disconnected, a turning force for turning the wheels 2 is applied to the rack shaft 5 through the second pinion shaft 16. When the second turning motor 36 is driven with the clutch 6 connected, an assist force that assists the steering operation by the driver is applied to the rack shaft 5 through the second pinion shaft 16. The speed reduction mechanism 38 has a worm shaft 38 a connected to the output shaft of the second steering motor 36, and a worm wheel 38 b that meshes with the worm shaft 38 a and is connected to the second pinion shaft 16.

  The reaction force motor 41 is provided such that the rotor rotates together with the first steering shaft 3. Therefore, when the reaction force motor 41 is driven with the clutch 6 disengaged, a steering reaction force is applied to the first steering shaft 3 in response to the driver's steering operation. As a result, a pseudo steering wheel weight can be given to the driver's steering operation. Further, in a state where the clutch 6 is connected, the reaction force motor 41 is disconnected from the reaction force controller 45 so as not to be a load of the steering operation, and is in a no-load state.

  Next, steering control by the steering control device 100 will be described.

  Normally, the clutch 6 is disengaged and steer-by-wire control is performed. In the steer-by-wire control, the first turning controller 35 controls the first turning motor 31 according to the operation state of the steering wheel 1, and the second turning controller 37 depends on the operation state of the steering wheel 1. The second steering motor 36 is controlled. Thereby, the wheel 2 is steered. Specifically, the first turning controller 35 and the second turning controller 37 first set a target turning angle based on the detection result of the steering angle sensor 21 and the vehicle speed. Next, based on the detection results of the first rotation angle sensor 22 and the second rotation angle sensor 23, the first turning controller 35 and the second turning controller 37 match the turning angle of the wheel 2 with the target turning angle. Thus, the first steered motor 31 and the second steered motor 36 are respectively controlled. More specifically, the first turning controller 35 and the second turning controller 37 include the rotation angle of the input shaft 11 and the first pinion shaft 12 detected by the first rotation angle sensor 22 and the second rotation angle sensor 23. The amount of movement of the rack shaft 5 in the axial direction is calculated from the rotation angle. That is, the amount of movement of the rack shaft 5 in the axial direction is calculated from the rotation angle of the second steering shaft 4. Then, the actual turning angle of the wheel 2 is calculated from the amount of movement of the rack shaft 5 in the axial direction so that the calculated actual turning angle of the wheel 2 coincides with the set target turning angle. The first steering motor 31 and the second steering motor 36 are controlled. The first turning motor 31 and the second turning motor 36 share the necessary turning force and output it.

  As described above, the detection results of the first rotation angle sensor 22 and the second rotation angle sensor 23 are used when controlling the first turning motor 31 and the second turning motor 36 during the steer-by-wire control. Therefore, it is not necessary to provide the first turning motor 31 and the second turning motor 36 with a resolver that detects a motor rotation angle that has been conventionally required.

  In the state where the clutch 6 is disengaged, the torsion bar 13 is not twisted, so that the rotation angle of the input shaft 11 and the rotation angle of the first pinion shaft 12 coincide. Therefore, when controlling the 1st steering motor 31 and the 2nd steering motor 36, it is not necessary to use both the detection results of the 1st rotation angle sensor 22 and the 2nd rotation angle sensor 23, and at least one detection is carried out. The result may be used.

  Further, in the steer-by-wire control, the reaction force controller 45 controls the reaction force motor 41 according to the steered state of the wheel 2 and applies a steering reaction force to the steering wheel 1. Specifically, the reaction force controller 45 sets a target steering reaction force corresponding to the reaction force received from the road surface by the steering operation, and the steering reaction force applied to the first steering shaft 3 matches the target steering reaction force. Thus, the reaction force motor 41 is controlled.

  When each of the first steering controller 35, the second steering controller 37, and the reaction force controller 45 determines that there is an abnormality in its own control system, the clutch 6 is connected and the steering control is changed from the steer-by-wire control to the assist control. Switch. The clutch 6 switches from a disconnected state to a connected state when an abnormality occurs in any of the control systems of the first steering controller 35, the second steering controller 37, and the reaction force controller 45. Here, in the case of the first steering controller 35, the control system is a system that controls the first steering motor 31 including the first steering motor 31 and the first steering controller 35 itself. In the case of the steering controller 37, the system controls the second steering motor 36 including the second steering motor 36 and the second steering controller 37 itself, and in the case of the reaction force controller 45, the reaction force motor. 41 and the reaction force controller 45 itself is a system for controlling the reaction force motor 41.

  When the reaction force controller 45 determines that there is an abnormality in its own control system, the abnormality information is transmitted from the reaction force controller 45 to the first turning controller 35 and the second turning controller 37 and the clutch 6 is turned on. Connected and switches from steer-by-wire control to assist control. Specifically, the first turning controller 35 and the second turning controller 37 calculate the torsion amount of the torsion bar 13 from the difference between the rotation angles detected by the first rotation angle sensor 22 and the second rotation angle sensor 23. The steering torque input by the steering operation is calculated from the twist amount. Based on the calculated steering torque, the first turning motor 31 and the second turning motor 31 are assisted such that an assist force for assisting the steering operation by the driver is applied to the first pinion shaft 12 and the second pinion shaft 16. The rudder motor 36 is controlled. The first turning motor 31 and the second turning motor 36 share the necessary assist force and output it. At the time of assist control by the first turning motor 31 and the second turning motor 36, the reaction force motor 41 is disconnected from the reaction force controller 45 so as not to be a load of the steering operation and is in a no-load state.

  As described above, when an abnormality occurs in the reaction force motor 41 or the system that controls the reaction force motor 41, assist control by the first turning motor 31 and the second turning motor 36 is performed. At this time, the steering torque input by the steering operation is detected based on the torsion amount of the torsion bar 13 calculated from the difference between the rotation angles detected by the first rotation angle sensor 22 and the second rotation angle sensor 23. Therefore, a torque sensor that has been conventionally required for assist control becomes unnecessary.

  When the first turning controller 35 determines that there is an abnormality in its own control system, the abnormality information is transmitted from the first turning controller 35 to the second turning controller 37 and the reaction force controller 45 and the clutch. 6 is connected to switch from steer-by-wire control to assist control. Specifically, the second turning controller 37 calculates the torsion amount of the torsion bar 13 from the difference between the rotation angles detected by the first rotation angle sensor 22 and the second rotation angle sensor 23, and performs the steering operation from the torsion amount. The steering torque input by is calculated. Then, based on the calculated steering torque, the second turning motor 36 is controlled so that an assist force for assisting the steering operation by the driver is applied to the second pinion shaft 16. At the time of assist control by the second steering motor 36, the reaction force motor 41 is disconnected from the reaction force controller 45 so as not to be a load of the steering operation and is in a no-load state. As described above, when an abnormality occurs in the first turning motor 31 or the system that controls the first turning motor 31, assist control by only the second turning motor 36 is performed.

  Similarly, when an abnormality occurs in the second turning motor 36 or the system that controls the second turning motor 36, assist control by only the first turning motor 31 is performed.

  According to the above embodiment, there exist the effects shown below.

  During steer-by-wire control, based on the detection results of the first rotation angle sensor 22 and the second rotation angle sensor 23, the first turning is performed so that the actual turning angle of the wheel 2 matches the set target turning angle. The motor 31 and the second steering motor 36 are controlled. On the other hand, during the assist control, the first turning motor 31 and the second turning motor 31 are based on the torsion amount of the torsion bar 13 calculated from the difference between the rotation angles detected by the first rotation angle sensor 22 and the second rotation angle sensor 23. The rudder motor 36 is controlled. Thus, the first rotation angle sensor 22 and the second rotation angle sensor 23 are used in both steer-by-wire control and assist control. That is, a common sensor is used for both steer-by-wire control and assist control. Therefore, it is not necessary to provide the first turning motor 31 and the second turning motor 36 with a resolver that detects a motor rotation angle that has been conventionally required, and a torque sensor that has been conventionally required for assist control is unnecessary. It becomes. Therefore, the number of sensors necessary for steering control can be reduced. Although the number of sensors is reduced as compared with the conventional one, the steering control equivalent to the conventional one can be performed as described above. As described above, according to the present embodiment, the cost can be reduced while maintaining the control performance.

  The steering angle sensor 21 detects an absolute rotation angle of the first steering shaft 3, that is, the steering wheel 1, and the first rotation angle sensor 22 and the second rotation angle sensor 23 correspond to the second steering shaft 4. The absolute rotation angle is detected. Therefore, for example, the steering wheel 1 is operated in a state where the clutch 6 is disconnected with the ignition OFF, and the rotational position of the steering wheel 1 and the turning angle of the wheel 2 deviate from a predetermined relationship. Even in this case, when the ignition is turned on, the rotational position of the steering wheel 1 and the wheel 2 are determined based on the detection result of the steering angle sensor 21 and the detection results of the first rotation angle sensor 22 and the second rotation angle sensor 23. The deviation from the steering angle can be easily corrected.

  Below, the modification of the said embodiment is demonstrated.

  (1) In the said embodiment, the case where there were two steering motors was shown. However, the number of steered motors is not limited to this. In the said embodiment, the structure which abolishes any one of the 1st steering motor 31 and the 2nd steering motor 36, and is equipped with only one steering motor with a big output may be sufficient. That is, what is necessary is just the structure provided with at least one steering motor. When there is only one steered motor, it is desirable that the steered motor is a fault tolerant motor that includes a plurality of systems having a motor coil and a controller that drives the motor coil.

  (2) In the above embodiment, the configuration is such that the steer-by-wire control is switched to the assist control at the time of fail-safe. Instead of this, a configuration may be adopted in which the steering control is switched from the steer-by-wire control to the assist control by a driver's operation even during normal times.

  (3) In the above embodiment, the first pinion shaft 12 constituting a part of the second steering shaft 4 has the pinion gear 12a formed at one end meshed with the rack gear 5a of the rack shaft 5 and the other end to the torsion bar 13. It is the structure connected. Instead of this, an intermediate shaft for connecting the torsion bar 13 and the first pinion shaft 12 may be provided. In this case, the intermediate shaft has one end connected to the torsion bar 13 and the other end connected to the first pinion shaft 12 via a universal joint. In this configuration, the intermediate shaft corresponds to the output shaft.

  Hereinafter, the configuration, operation, and effect of the embodiment of the present invention will be described together.

  In the present embodiment, the first steering shaft 3 that rotates in accordance with the steering operation by the driver, the second steering shaft 4 that is connected to the rack shaft 5 that steers the wheels 2, the first steering shaft 3, and the second steering shaft 3. A clutch 6 that switches connection and disconnection of the steering shaft 4, a first turning motor 31 and a second turning motor 36 that apply a turning force to the rack shaft 5 in a state where the clutch 6 is disconnected, and steering operation. A steering angle sensor 21 for detecting the steering angle involved, a torsion bar 13 provided as a part of the second steering shaft 4 and torsionally deformed when the steering operation is performed with the clutch 6 connected, and a second steering shaft 4 detects the rotation angle of the input shaft 11 provided as a part of 4 and connected to one end of the torsion bar 13. A first rotation angle sensor 22, a second rotation angle sensor 23 for detecting the rotation angle of the first pinion shaft 12 provided as a part of the second steering shaft 4 and connected to the other end of the torsion bar 13, and the first rotation shaft A first steering controller 35 and a second steering controller 37 that control driving of the steering motor 31 and the second steering motor 36, and the first steering controller 35 and the second steering controller 37 are provided with the clutch 6. Is disconnected, the first turning motor 31 and the second turning motor 36 are turned on based on the detection result of the steering angle sensor 21 and at least one of the first rotation angle sensor 22 and the second rotation angle sensor 23. In the state where the steer-by-wire control is performed and the clutch 6 is connected, it is calculated from the difference between the rotation angles detected by the first rotation angle sensor 22 and the second rotation angle sensor 23. That based on the torsion amount of the torsion bar 13 to assist control for assisting the steering operation by the driver controls the first steering motor 31 and second steering motor 36.

  In this configuration, in both the steer-by-wire control and the assist control, the first rotation angle sensor 22 and the second rotation angle sensor 23 provided on each of the input shaft 11 and the first pinion shaft 12 connected to the torsion bar 13 are provided. Used. Therefore, the number of sensors necessary for steering control can be reduced. Therefore, in the steering control device 100 having the steer-by-wire structure, the cost can be reduced while maintaining the control performance.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  For example, in the above-described embodiment, the configuration in which the driving force of the steering motors 31 and 36 is output to the pinion shafts 12 and 16 via the speed reduction mechanisms 32 and 38 has been described. Alternatively, a configuration (belt drive system) in which the driving force of the steering motor is applied to the rack shaft 5 via a speed reduction mechanism having a pulley and a belt may be used. It is good also as a structure (direct drive system) provided directly to the rack shaft 5 without using a mechanism.

DESCRIPTION OF SYMBOLS 100 ... Steering control apparatus, 1 ... Steering wheel, 2 ... Wheel, 3 ... 1st steering shaft, 4 ... 2nd steering shaft, 5 ... Rack axis, 6 ... Clutch (connection switching unit), 11 ... input shaft, 12 ... first pinion shaft (output shaft), 13 ... torsion bar, 21 ... steer angle sensor, 22 ... first rotation angle Sensor, 23 ... 2nd rotation angle sensor, 31 ... 1st steering motor, 35 ... 1st steering controller, 36 ... 2nd steering motor, 37 ... 2nd steering Controller, 41 ... reaction force motor, 45 ... reaction force controller

Claims (1)

A first steering shaft that rotates in accordance with a steering operation by a driver;
A second steering shaft coupled to a rack shaft for steering the wheels;
A connection switching unit that switches connection and disconnection between the first steering shaft and the second steering shaft;
In a state where the connection switching unit is disconnected, a steering motor that applies a steering force to the rack shaft,
A steering angle sensor for detecting a steering angle associated with a steering operation;
A torsion bar provided as a part of the second steering shaft and torsionally deformed when a steering operation is performed with the connection switching portion connected;
A first rotation angle sensor for detecting a rotation angle of an input shaft provided as a part of the second steering shaft and connected to one end of the torsion bar;
A second rotation angle sensor for detecting a rotation angle of an output shaft provided as a part of the second steering shaft and connected to the other end of the torsion bar;
A steering controller for controlling the driving of the steering motor,
The steering controller
In a state where the connection switching unit is disconnected, the steered motor is controlled by controlling the steered motor based on a detection result of at least one of the first rotation angle sensor and the second rotation angle sensor and the steering angle sensor. Control
In a state where the connection switching unit is connected, the steering motor is controlled based on a twist amount of the torsion bar calculated from a difference in rotation angle detected by the first rotation angle sensor and the second rotation angle sensor. A steering control device that performs assist control to control and assist a steering operation by a driver.

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