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CN-115071808-B - Device for assisting steering of vehicle and control method thereof

CN115071808BCN 115071808 BCN115071808 BCN 115071808BCN-115071808-B

Abstract

A device for assisting steering of a vehicle and a control method thereof may include a turning direction identifier identifying a turning direction of a tire using a steering angle controlled by a manipulation handle, and a tire driving controller determining a tire to which a first driving force is applied and a tire to which a second driving force is applied, and controlling driving motors provided to the respective tires to generate a first driving force for generating a steering assist torque assisting the tire to turn to the identified turning direction and a second driving force for canceling the first driving force to keep a forward/backward force of the vehicle at 0 so that the tire may turn with a limit steering torque or more that can be generated by the steering motor, respectively.

Inventors

  • XU ZHIYIN

Assignees

  • 现代自动车株式会社
  • 起亚株式会社

Dates

Publication Date
20260512
Application Date
20211021
Priority Date
20210311

Claims (14)

  1. 1. An apparatus for assisting steering of a vehicle, the apparatus comprising: A turning direction identifier configured to identify a turning direction of a tire to which the vehicle turns using a steering angle controlled by the steering handle, and A tire driving controller configured to determine a tire to which a first driving force is applied and a tire to which a second driving force is applied, and to control driving motors provided to the respective tires to generate a first driving force for generating a steering assist torque for assisting the tire in turning to the identified turning direction and a second driving force for canceling the first driving force to keep a forward/backward force of the vehicle at 0, respectively; wherein the tire drive controller is configured to: As a tire to which the first driving force is applied, a front wheel on the vehicle outer side is determined as a tire to which a positive (+) driving force is applied, and a front wheel on the vehicle inner side is determined as a tire to which a negative (-) driving force is applied, with reference to a turning direction in which the tire turns; as a tire to which the second driving force is applied, the rear wheel on the vehicle inner side is determined as a tire to which the positive (+) driving force is applied, and the rear wheel on the vehicle outer side is determined as a tire to which the negative (-) driving force is applied, with reference to the turning direction in which the tire turns.
  2. 2. The apparatus for assisting steering of a vehicle according to claim 1, further comprising: a stop determiner configured to previously determine whether the vehicle is stopped by using a wheel speed of the vehicle.
  3. 3. The apparatus for assisting steering of a vehicle according to claim 1, wherein the tire drive controller is configured to perform control to apply positive (+) driving force as the first driving force to a right front wheel of the vehicle and negative (-) driving force as the first driving force to a left front wheel of the vehicle and to apply positive (+) driving force as the second driving force to a left rear wheel of the vehicle and to apply negative (-) driving force as the second driving force to a right rear wheel of the vehicle when steering the vehicle in a stopped state to turn left.
  4. 4. The apparatus for assisting steering of a vehicle according to claim 1, wherein the tire drive controller is configured to perform control to apply positive (+) driving force as the first driving force to a left front wheel of the vehicle and negative (-) driving force as the first driving force to a right front wheel of the vehicle and to apply positive (+) driving force as the second driving force to a right rear wheel of the vehicle and to apply negative (-) driving force as the second driving force to a left rear wheel of the vehicle when steering the vehicle in a stopped state to a right turn.
  5. 5. The apparatus for assisting steering of a vehicle according to claim 1, further comprising: A moment arm calculator configured to store data representing an incremental relation of the steering angle and the moment arm in a memory by previously determining the data using specification characteristic values of the vehicle including mounting positions of the kingpin and the steering motor and an offset of the motor shaft, and recognize a length of the moment arm changed when the tire turns through the memory using a magnitude of the steering angle.
  6. 6. The apparatus for assisting steering of a vehicle according to claim 1, further comprising: A steering assist determiner configured to determine a magnitude of a required steering torque required to turn the tire in the left or right turning direction in a state where the vehicle is stopped, based on the magnitude of the steering angle, and determine a portion of the required steering torque that is assisted by the first driving force and the second driving force generated by the driving motor when the required steering torque is greater than a limit steering torque generated by the steering motor.
  7. 7. The apparatus for assisting steering of a vehicle according to claim 6, wherein the steering assist determiner is configured to determine a ratio of steering torque generated by the steering motor to steering assist torque generated by the driving motor among the required steering torque.
  8. 8. A method of controlling steering of an auxiliary vehicle, the method comprising: A turning direction identification step of identifying a turning direction of a tire to which the vehicle turns, using a steering angle controlled by the steering handle; A tire drive control step of determining a tire to which a first driving force is applied and a tire to which a second driving force is applied, and controlling driving motors provided to the respective tires to generate a first driving force for generating a steering assist torque for assisting the tire in turning to the identified turning direction and a second driving force for canceling the first driving force to keep a forward/backward force of the vehicle at 0, respectively; wherein the tire driving control step includes: As a tire to which the first driving force is applied, a front wheel on the vehicle outer side is determined as a tire to which a positive (+) driving force is applied, and a front wheel on the vehicle inner side is determined as a tire to which a negative (-) driving force is applied, with reference to a turning direction in which the tire turns; as a tire to which the second driving force is applied, the rear wheel on the vehicle inner side is determined as a tire to which the positive (+) driving force is applied, and the rear wheel on the vehicle outer side is determined as a tire to which the negative (-) driving force is applied, with reference to the turning direction in which the tire turns.
  9. 9. The method as recited in claim 8, further comprising: a vehicle stop determination step of determining whether the vehicle is stopped by using the wheel speed of the vehicle before the change of the steering angle is recognized in the turning direction recognition step.
  10. 10. The method as recited in claim 8, further comprising: A steering assist determination step of determining, prior to the tire drive control step, a magnitude of a required steering torque required to turn the tire in the left-turn direction or the right-turn direction in a state where the vehicle is stopped, based on the magnitude of the steering angle, and determining a portion of the required steering torque that is assisted by the first driving force and the second driving force generated by the driving motor when the required steering torque is greater than the limit steering torque generated by the steering motor.
  11. 11. The method of claim 10, wherein the steering assist determining step includes: a ratio of the steering torque generated by the steering motor to the steering assist torque generated by the drive motor among the required steering torque is determined.
  12. 12. The method as recited in claim 8, further comprising: Control is performed such that, when the vehicle in a stopped state is turned to a left turn, positive (+) driving force is applied to the right front wheel of the vehicle and negative (-) driving force is applied to the left front wheel of the vehicle as a first driving force, and positive (+) driving force is applied to the left rear wheel of the vehicle as a second driving force and negative (-) driving force is applied to the right rear wheel of the vehicle as a second driving force.
  13. 13. The method as recited in claim 8, further comprising: control is performed such that, when the vehicle in a stopped state is turned to a right turn, positive (+) driving force is applied to the left front wheel of the vehicle and negative (-) driving force is applied to the right front wheel of the vehicle as a first driving force, and positive (+) driving force is applied to the right rear wheel of the vehicle as a second driving force and negative (-) driving force is applied to the left rear wheel of the vehicle as a second driving force.
  14. 14. The method as recited in claim 8, further comprising: The data representing the incremental relationship of the steering angle and the moment arm is stored in a memory by previously determining the data using the specification characteristic value of the vehicle including the mounting positions of the kingpin and the steering motor and the offset of the motor shaft, and the length of the moment arm changed when the tire turns is recognized by the memory using the magnitude of the steering angle.

Description

Device for assisting steering of vehicle and control method thereof Cross Reference to Related Applications The present application claims priority from korean patent application No.10-2021-0032227, filed on 3 months 11 of 2021, the entire contents of which are incorporated herein by reference for all purposes. Technical Field The present invention relates to an apparatus for assisting steering of a vehicle, which can additionally provide torque required to stop steering of the vehicle from a driving motor, and a control method thereof. Background In general, when a vehicle is steered by using electric power assisted steering (MDPS), steering torque applied to each tire for a required steering angle differs depending on whether the vehicle is driven or stopped. That is, the steering torque required when the vehicle is stopped is larger than the steering torque required when the coefficient of friction between the tire and the road surface on which the vehicle is running is small, and the required steering torque increases as the steering angle increases. Therefore, in the case of a complete turn in a stopped state (in which the steering angle is maximally operated), the maximum steering torque is required. Further, in four-wheel independent steering wheels in which four tires can be independently driven, there is a space limitation in increasing the capacity and the magnitude of steering torque since it is necessary to provide a driving motor for generating driving force at the tires and a steering motor for generating steering torque at the tires. Therefore, there is a need for a device that can satisfy the steering torque required during a full turn in a stopped state (in which the maximum steering torque is required during steering while the increase in the capacity of the steering motor is minimized). The information disclosed in the background section of the invention is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. Disclosure of Invention Various aspects of the present invention are directed to providing an apparatus for assisting steering of a vehicle and a control method thereof, the apparatus including a turning direction identifier for identifying a turning direction of a tire to which the vehicle is turned using a steering angle controlled by a manipulation handle, and a tire driving controller for determining a tire to which a first driving force for generating a steering assist torque for assisting the tire to turn to the identified turning direction and a tire to which a second driving force for canceling the first driving force to maintain a forward/backward force of the vehicle at 0 are applied, and controlling driving motors provided to the respective tires to generate the first driving force and the second driving force, respectively, such that the tire can be turned with a limit steering torque or more that can be generated by the steering motors. The technical problems solved by the inventive concept are not limited to the above-described problems, and any other technical problems not mentioned herein will be clearly understood by those skilled in the art to which various exemplary embodiments of the present invention belong from the following description. According to aspects of the present invention, an apparatus for assisting steering of a vehicle includes a turning direction identifier that identifies a turning direction of a tire to which the vehicle is turned using a steering angle controlled by a steering handle, and a tire driving controller that determines a tire to which a first driving force for generating a steering assist torque for assisting the tire to turn to the identified turning direction is applied and a tire to which a second driving force for canceling the first driving force to maintain a forward/backward force of the vehicle at 0 is applied, and controls driving motors provided to the respective tires to generate the first driving force and the second driving force, respectively. Further, the apparatus may further include a stop determiner that previously determines whether the vehicle is stopped by using a wheel speed of the vehicle. Further, the tire driving controller may determine, as the tire to which the first driving force is applied, the front wheel on the vehicle outer side as the tire to which the positive (+) driving force is applied and the front wheel on the vehicle inner side as the tire to which the negative (-) driving force is applied, based on the turning direction in which the tire is turned. Further, the tire driving controller may determine, as the tire to which the second driving force is applied, the rear wheel on the vehicle inner side as the tire to which the positive (+) driving force is applied and the rear wheel on the vehicle outer side as the