Steer-by-wire system, and control method for steer-by-wire system
A steer-by-wire control method is provided for a steer-by-wire system mounted in a vehicle that is equipped with an engine and a battery. The steer-by-wire control method stores a deviation angle between a steering angle and a turning angle in a non-volatile memory of the steer-by-wire system as a readable value when an ignition switch is switched from ON to OFF. The steer-by-wire control method further reads the deviation angle from the non-volatile memory when the ignition switch is switched from OFF to ON. The steer-by-wire control method further prohibits further reading of the deviation angle from the non-volatile memory after reading the deviation angle from the non-volatile memory and after reading the deviation angle from the non-volatile memory and after starting the steer-by-wire control.
1. A steer-by-wire control method for a steer-by-wire system that is mounted in a vehicle equipped with an engine and a battery, and that is provided with a torque transmission path that can connect or separate a steering wheel and turning wheels, the control method comprising:
a step to detect a steering angle of the steering wheel;
a step to detect a turning angle of the turning wheels; and
a steer-by-wire control step to control the turning angle of the turning wheels based on the steering angle and the turning angle in a state in which the torque transmission path between the steering wheel and the turning wheels is mechanically separated;
storing a deviation angle between the steering angle and the turning angle in a non-volatile memory of the steer-by-wire system as a readable value when an ignition switch is switched from ON to OFF;
reading the deviation angle from the non-volatile memory when the ignition switch is switched from OFF to ON; and
prohibiting further reading of the deviation angle from the non-volatile memory after reading the deviation angle from the non-volatile memory and after reading the deviation angle from the non-volatile memory and after starting the steer-by-wire control.
2. A steer-by-wire control method for a steer-by-wire system that is mounted in a vehicle that is equipped with an engine and a battery, and that is provided with a torque transmission path that can connect or separate a steering wheel and turning wheels, the control method comprising:
a step to detect a steering angle of the steering wheel;
a step to detect a turning angle of the turning wheels; and
a steer-by-wire control step to control the turning angle of the turning wheels based on the steering angle and the turning angle in a state in which the torque transmission path between the steering wheel and the turning wheels is mechanically separated,
storing a deviation angle between the steering angle and the turning angle in a non-volatile memory of the steer-by-wire system as a readable value when an ignition switch is switched from ON to OFF;
reading the deviation angle from the non-volatile memory when the ignition switch is switched from OFF to ON; and
permitting reading of the deviation angle stored in the non-volatile memory when the ignition switch is ON until a battery voltage is detected to be equal to or greater than a predetermined value, and an engine rotation speed during a predetermined period after the engine rotation speed becomes equal to or greater than a first predetermined value is equal to or greater than a second predetermined value, which is equal to or less than the first predetermined value.
3. The steer-by-wire control method as recited in claim 1 , wherein
the step to detect the steering angle of the steering wheel is a step to detect with a steering angle sensor the current steering angle, and
the step to detect the turning angle of the turning wheels is a step to detect a deviation angle between the steering angle at a time of starting detection and a position of the turning wheels, and a rotation angle from the position of the turning wheels at the time of starting detection and the current position of the turning wheels, and to detect the turning angle of the turning wheels based on the detected steering angle, the initial deviation angle, and the detected rotation angle.
4. The steer-by-wire control method as recited in claim 1 , wherein
a clutch is provided in a torque transmission path between the steering wheel and the turning wheels, and further comprising
disengaging the clutch and prohibiting reading deviation angle from the non-volatile memory.
5. A steer-by-wire system for a vehicle that is equipped with an engine and a battery, and that is provided with a torque transmission path that can connect or separate a steering wheel and turning wheels, the steer-by-wire system comprising:
a steering angle sensor that detects a steering angle of the steering wheel;
a turning angle sensor that detects a turning angle of the turning wheels; and
a steer-by-wire controller that controls the turning angle of the turning wheels based on the steering angle and the turning angle in a state in which the torque transmission path between the steering wheel and the turning wheels is mechanically separated,
the steer-by-wire controller being configured to store a deviation angle between the steering angle and the turning angle in a non-volatile memory of the steer-by-wire system as a readable value when an ignition switch is switched from ON to OFF;
the steer-by-wire controller being configured to read the deviation angle from the non-volatile memory when the ignition switch is switched from OFF to ON; and
the steer-by-wire controller being configured to prohibit further reading of the deviation angle from the non-volatile memory after reading the deviation angle from the non-volatile memory and after reading the deviation angle from the non-volatile memory and after starting the steer-by-wire control.
6. The steer-by-wire control method as recited in claim 2 , wherein
the step to detect the steering angle of the steering wheel is a step to detect with a steering angle sensor the current steering angle, and
the step to detect the turning angle of the turning wheels is a step to detect a deviation angle between the steering angle at a time of starting detection and a position of the turning wheels, and a rotation angle from the position of the turning wheels at the time of starting detection and the current position of the turning wheels, and to detect the turning angle of the turning wheels based on the detected steering angle, the initial deviation angle, and the detected rotation angle.
7. The steer-by-wire control method as recited in claim 2 , wherein
a clutch is provided in a torque transmission path between the steering wheel and the turning wheels, and further comprising
disengaging the clutch and prohibiting reading deviation angle from the non-volatile memory.