Dual-Redundancy Control Of Dual-Redundancy Steer-by-Wire System

Dual-redundancy Steer-by-Wire system(DSBW)is a high safety reliability Steerby-Wire system proposed by applying the redundancy theory to the design of the system to solve the problem of insufficient safety and reliability of the conventional Steer-byWire system.Under normal circumstances,the 2 dual-redundancy subsystems-the steering wheel and the steering gear subsystems-are coupled to work to realize the vehicle steering function;in the case of any single failure,the system can continue to perform the steering function normally without being affected.The control method that enables DSBW to realize the function of steering-by-wire and at the same time has the dualredundancy working mechanism is called dual-redundancy control.The control architecture of the conventional Steer-by-Wire system is difficult to achieve a dual-redundancy working mechanism.For the system control architecture problem,a two-system dual-redundancy control coupled through dual-redundancy information architecture is proposed,which is the overall architecture of the dualredundancy control of DSBW.Dual-redundancy control architecture is adopted on 2 dualredundancy subsystems-the steering wheel and steering gear subsystems-to ensure the high safety and reliability of subsystem control and decouple the control of 2 channels in each subsystem.A dual-redundancy information coupling control architecture is adopted between the 2 dual-redundancy subsystems,which is a high safety reliability information coupling way and decouples the control of 2 subsystems.The architecture matches the system structure and is the basis of the high safety reliability of dual-redundancy control.For the control problem of dual-redundancy steering gear subsystem,a dualredundancy steering control method with self-learning interference elimination variable transmission ratio is proposed.The interference problem caused by the steering wheel and steering gear cannot reach their respective mechanical limit angles at the same time is solved by the variable transmission ratio with self-learning interference elimination function,making the 2 subsystems have the state of being at the limit position at the same time to achieve maximum steering capability.The dual-motors are controlled in coordination,of which the output currents are proportional to a fixed ratio to avoid the torque dispute problem.Three controllers are used to reduce the order of the subsystem and fast and smooth order-reduce and reforming control is realized to restore the steering function.For the control problem of dual-redundancy steering wheel subsystem,a steering wheel angular position and force coupled multi-mode dual-redundancy control method is proposed.A suitable steering feel torque is generated while the steering wheel angle can be controlled simultaneously to avoid the steering out of control problem after release.A multi-mode control method is adopted to make the subsystem work in line with control requirements and operating habits under different vehicle driving conditions,which are angle consistency control mode,vehicle-running steering control mode and pivot steering control mode.The steering feel before failure can be restored rapidly after the system order-reduce with torque rapid compensation order-reduce and reforming control.A Simulink-Car Sim joint simulation platform and a vehicle test platform are established.The two-system dual-redundancy control coupled through dual-redundancy information architecture,the dual-redundancy steering control method with self-learning interference elimination variable transmission ratio and the steering wheel angular position and force coupled multi-mode dual-redundancy control method are verified.The test results prove the feasibility and effectiveness of the proposed dual-redundancy control method.