Driving Intention Recognition And Bilateral Synchronous Control In The Steering By Wire Control System For Vehicles

The steering by wire control system for vehicles that is based on the traditional structure of mechanical steering system, abandons the mechanical steering column between steering wheel and steering gear and accomplishes the interaction of information needed for steering of vehicles by wire. The abandon of mechanical steering column make the steering by wire control system have many kinds of advantages, such as improving handling stability, passive safety and ride comfort of vehicles, improving the driving condition in vehicles, but at the same time requires electronic control to fulfill the basic functions of the steering by wire control system. Therefore, the research proceeds from the aspects of three subsystems including electronic control steering wheel system, electronic control steering gear system and communication by wire network, to realize the main functions of the steering by wire control system and build hardware-in-the-loop test bench system for validation, which can provide basic test bench conditions for the further study in reliability issue of the steering by wire control system for vehicles.The electronic control steering wheel system, with a steering wheel as the human machine interface between the driver and the electronic control steering wheel system, combines the steering shaft torque gradient and steering wheel manipulating angle to recognize different manipulating modes of steering wheel, which can provide basic technology for the bilateral synchronization control between the electronic control steering wheel system and the electronic control steering gear system. A calculating method of aligning torque regeneration is designed, on the basis of direct current measurement of steering gear motor combining steering wheel angle information, to realize the regeneration of aligning torque.The angle tracking of steering wheel is accomplished while the electronic control steering gear system is active machine, imitating the free return-to-center characteristics for vehicles.The electronic control steering gear system, in consideration of drivers’ requirement of convenience and flexibility in the vehicle steering manipulating, has the variable angle ratio characteristic with the variation of steering wheel manipulating angle. At different manipulating modes of steering wheel, the bilateral synchronization control proceeds between the electronic control steering wheel system and the electronic control steering gear system, through PID closed-loop control algorithms, to realize the relevant target angle tracking control in the mode in which the electronic control steering wheel system is active machine, ensuring the original steering for vehicles.The communication by wire network system uses appropriate sensors to acquire the status information that is needed to interact in the electronic control steering wheel system and the electronic steering gear system. Based on CAN bus technology, the communication by wire network system encodes digital information to form information frames in accordance with CAN2.0B protocol, and accomplishes the interaction of information between the electronic control steering wheel system and the electronic control steering gear system for the status information providing in their functions control, by transmitting and receiving of relevant information frames.Finally, hardware-in-the-loop test bench system is built. Tests about aligning torque regeneration, steering gear pinion angle tracking, steering wheel manipulating mode recognition as well as the bilateral synchronization control are completed on the test bench system, which verifies the realization of main functions of the steering by wire control system for vehicles and the feasibility of the research solutions in this thesis.