Steering assist system for motorcycle

1. A steering assist system for a motorcycle, the motorcycle comprising a vehicle body including a front steering wheel and a rear drive wheel, a handlebar coupled to a head pipe and disposed on a front portion of the vehicle body, and a bridge mounted to the head pipe, the steering assist system comprising:

an actuator connected to the vehicle body and to the bridge, the actuator configured to provide a steering torque for steering of the motorcycle;

a steering torque sensor attached to the head pipe and configured to detect the steering torque provided by the actuator; and

a controller mounted to the vehicle body and connected to the steering torque sensor and to the actuator;

the controller comprising a target torque calculation unit configured to obtain a target torque for the steering on a basis of a state of the motorcycle and a torque control unit configured to drive the actuator on a basis of a deviation between the target torque obtained from the target-torque calculation unit and the steering torque obtained from the torque detecting unit.

2. The steering assist system for a motorcycle according to claim 1 , further comprising:

a steering angle sensor connected to the controller and configured to detect a state concerning a steering angle of the steering;

an acceleration sensor connected to the controller and configured to detect an acceleration in a vehicle-width direction of the motorcycle; and

a vehicle-speed sensor connected to the controller and configured to detect a vehicle speed of the motorcycle,

wherein the target-torque calculation unit obtains the target torque on a basis of the information obtained from the steering angle sensor, the acceleration in the vehicle-width direction obtained from the acceleration sensor, and the vehicle speed obtained from the vehicle-speed sensor.

3. The steering assist system for a motorcycle according to claim 2 ,

wherein the information obtained from the steering angle sensor is a steering-angle acceleration, and

when the acceleration in the vehicle-width direction is equal to or larger than a first predetermined value and the steering-angle acceleration is equal to or larger than a second predetermined value, the actuator is driven and provides a steering torque to the steering.

4. The steering assist system for a motorcycle according to claim 2 ,

wherein the target-torque calculation unit obtains the target torque through an inverse operation using at least one of a vehicle-body-behavior transfer function that expresses the acceleration in the vehicle-width direction with respect to the steering torque, and a vehicle-body-behavior transfer function that expresses the steering-angle acceleration with respect to the steering torque.

5. The steering assist system for a motorcycle according to 3 ,

wherein the target-torque calculation unit obtains the target torque through an inverse operation using at least one of a vehicle-body-behavior transfer function that expresses the acceleration in the vehicle width direction with respect to the steering torque, and a vehicle-body-behavior transfer function that expresses the steering-angle acceleration with respect to the steering torque.

6. A steering assist system for a motorcycle, the motorcycle comprising a vehicle body including a front steering wheel and a rear drive wheel, a handlebar coupled to a head pipe and disposed on a front portion of the vehicle body, and a bridge mounted to the head pipe, said system comprising:

actuating means connected to the vehicle body and to the bridge, the actuating means for providing a steering torque for steering of a motor cycle;

steering torque sensing means attached to the head pipe, the steering torque sensing means for detecting the steering torque provided by the actuating means; and

controlling means mounted to the vehicle body and connected to the steering torque sensing means and to the actuating means,

the controlling means comprising a target torque calculating means for obtaining a target torque for the steering on a basis of a state of the motorcycle and torque controlling means for driving the actuating means on a basis of a deviation between the target torque obtained from the target-torque calculating means and the steering torque obtained from the torque detecting means.

7. The steering assist system for a motorcycle according to claim 6 , further comprising:

steering-angle-state detecting means for detecting a state concerning a steering angle of the steering, the steering-angle-state detecting means connected to the controlling means;

acceleration detecting means for detecting an acceleration in a vehicle-with direction of the motorcycle, the acceleration detecting means connected to the controlling means; and

vehicle-speed detecting means for detecting a vehicle speed of the motorcycle, the vehicle-speed detecting means connected to the controlling means,

wherein the target-torque calculation means obtains the target torque on a basis of the information obtained from the steering-angle-state detecting means, the acceleration in the vehicle-width direction obtained from the acceleration detecting means, and the vehicle speed obtained from the vehicle speed detecting means.

8. The steering assist system for a motorcycle according to claim 7 ,

wherein the information obtained from the steering-angle-state detecting means is a steering-angle acceleration, and

when the acceleration in the vehicle-width direction is equal to or larger than a first predetermined value and the steering-angle acceleration is equal to or larger than a second predetermined value, the actuator is driven and provides a steering torque to the steering.

9. The steering assist system for a motorcycle according to claim 7 ,

wherein the target-torque calculation means obtains the target torque through an inverse operation using at least one of a vehicle-body-behavior transfer function that expresses the acceleration in the vehicle width direction with respect to the steering torque, and a vehicle-body-behavior transfer function that expresses the steering-angle acceleration with respect to the steering torque.

10. The steering assist system for a motorcycle according to claim 8 ,

wherein the target-torque calculation means obtains the target torque through an inverse operation using at least one of a vehicle-body-behavior transfer function that expresses the acceleration in the vehicle width direction with respect to the steering torque, and a vehicle-body-behavior transfer function that expresses the steering-angle acceleration with respect to the steering torque.

11. A method for steering assist in a motorcycle, said method comprising:

obtaining a target torque for steering on a basis of a state of the motorcycle;

detecting a steering torque;

driving an actuator on a basis of a deviation between the target torque and the steering torque, thereby providing additional steering torque via the actuator.

12. A method according to claim 11 , further comprising:

detecting a state concerning a steering angle of the steering of the motorcycle;

detecting an acceleration in a vehicle-width direction of the motorcycle;

detecting a vehicle speed of the motorcycle,

wherein the target torque is obtained on a basis of information detected regarding the steering angle of the steering, the acceleration in the vehicle-width direction, and the vehicle speed.

13. A method as recited in claim 12 , wherein the detecting of the state concerning a steering angle of the steering comprises steering-angle acceleration, and wherein when the acceleration in the vehicle-width direction is equal to or larger than a first predetermined value, and the steering-angle acceleration is equal to or larger than a second predetermined value, steering torque is provided to the steering.

14. A method as recited in claim 12 , wherein the target torque is obtained through an inverse operation using at least one of a vehicle-body-behavior transfer function that expresses the acceleration in the vehicle-width direction with respect to the steering torque, and a vehicle-body-behavior transfer function that expresses the steering-angle acceleration with respect to the steering torque.

15. A method as recited in claim 13 , wherein the target torque is obtained through an inverse operation using at least one of a vehicle-body-behavior transfer function that expresses the acceleration in the vehicle-width direction with respect to the steering torque, and a vehicle-body-behavior transfer function that expresses the steering-angle acceleration with respect to the steering torque.