Distributed steering by wire control using time-triggered protocol communication network
View Patent ↗The present invention involves a distributed control system for controlling a steering movement of a vehicle. The system includes a driver interface assembly, a driver interface node having a first time-triggered protocol (TTP) processing system and a road wheel node having a second time-triggered protocol (TTP) processing system. The driver interface node having a first time-triggered protocol (TTP) processing system is coupled to the driver interface assembly, where the driver interface node receives steering wheel parameters from the driver interface assembly. The road wheel node having the second time triggered protocol (TTP) processing system is coupled to the driver interface node, where the road wheel node transmits sensor measurements from a vehicle to the driver interface node. The road wheel node generates an applied torque that adjusts a wheel of the vehicle.
1. A distributed control system for controlling a steering movement of a vehicle, the system comprising:
a driver interface assembly;
a driver interface node having a first time-triggered protocol (TTP) processing system coupled to the driver interface assembly, wherein the driver interface node receives steering wheel parameters from the driver interface assembly;
a road wheel node having a second time triggered protocol (TTP) processing system coupled to the driver interface node, wherein the road wheel node transmits sensor measurements from a vehicle to the driver interface node; and
wherein the road wheel node generates an applied torque that adjusts a wheel of the vehicle.
2. The system of claim 1 wherein the driver interface node generates a road wheel actuator reference based on the steering wheel parameters, wherein the driver interface node transmits the road wheel actuator reference to the road wheel node, wherein the road wheel node generates the applied torque based on the road wheel actuator reference.
3. The system of claim 2 wherein the driver interface node generates a reaction torque based on the steering wheel parameters and measurements from the vehicle.
4. The system of claim 2 wherein the road wheel actuator reference is transmitted to the road wheel node in a fault-tolerant manner.
5. The system of claim 4 wherein the fault-tolerant manner comprises a real-time fault-tolerant manner.
6. The system of claim 1 wherein the measurements from the vehicle are transmitted from the road wheel node to the driver interface node in a fault-tolerant manner.
7. The system of claim 1 wherein the driver interface node having the first TTP processing system comprises a microcontroller coupled to a time triggered protocol circuit.
8. The system of claim 7 wherein the microcontroller comprises a microprocessor.
9. The system of claim 7 wherein the microcontroller comprises a digital signal processor.
10. The system of claim 1 wherein the driver interface node is coupled to the road wheel node by a TTP communication bus.
11. The system of claim 1 wherein the road wheel node having the second TTP processing system comprises a microcontroller coupled to a TTP circuit.
12. The system of claim 1 wherein the measurements from the steering wheel parameters comprise measurements of a steering wheel angle.
13. The system of claim 2 wherein the road wheel node generates an electrical pulse width modulated signal.
14. The system of claim 13 further comprising power electronics that receive the electric pulse width modulated signal that moves the wheel of the vehicle.
15. The system of claim 14 , wherein the power electronics are operative to control a torque of an actuator.
16. The system of claim 14 wherein the measurements from the vehicle comprises vehicle speed, a lateral acceleration, a yaw rate, an absolute wheel position, an actuator current, an actuator position and an actuator temperature.
17. The system of claim 15 , wherein the power electronics are solid-state transistors.
18. The system of claim 15 , wherein the actuator adjusts the wheel of the vehicle.
19. The system of claim 3 , wherein the generated reaction torque is calculated in accordance with the following equation:
Reaction Torque k 1 *(Steering wheel angle—Road wheel angle)+ k 2 *lateral acceleration
k 1 = k 5 *(vehicle speed+ kv 2 )
k 2 = k 6 *(vehicle speed+ kv 3 )
where kv 2 , kv 3 , k 5 and k 6 are positive constant values known for the vehicle, steering wheel angle is a measurement from the steering wheel parameters, road wheel angle is a measurement from the road wheel node, vehiclespeed is measured from the vehicle and lateral acceleration is measured from the vehicle.
20. The system of claim 15 , wherein the applied torque is calculated in accordance with the following equation:
Applied Torque= K *(road wheel actuator reference—road wheel angle)
K=k 3 *(vehicle speed+ kv 1 ); if actuator temperature<actuator temperature threshold and actuator current<actuator current threshold, otherwise
K=k 3 *(vehicle speed+ kv )*( k 4 /max(|current|, |temperature|))
where k 3 , k 4 & kv 1 are positive constants, K is a function of a vehicle speed of the vehicle, road wheel angle is a measurement from the road wheel node, an actuator current of the actuator, an actuator temperature of the actuator, an actuator threshold current and an actuator threshold temperature are measurements stored in the road wheel node.
21. A distributed method for controlling the steering operation of a vehicle, the method comprising:
receiving measurements from a driver interface assembly;
receiving sensor measurements from a vehicle;
combining the received measurements from the driver interface assembly and sensor measurements from the vehicle in an applied torque equation to generate an applied torque; and
adjusting a wheel of the vehicle based on the applied torque.
22. The method of claim 21 , wherein the measurements from the vehicle, comprise a vehicle speed of the vehicle.