# A Systematic Review and Future Development of Automotive Classis Control Technology
## 2 Automotive Steering-By-Wire System  
### The State of the Art  
As shown in Figure 1, the automotive steering system has gone through several stages including a mechanical steering system, hydraulic-power-assisted steering (HPS) system, electro-hydraulic-power-assisted steering (EHPS) system, electric-power- assisted steering (EPS) system, and a steer-by-wire (SBW) system [7; 8]. The wire- controlled steering system eliminates the mechanical connection between the steering wheel and the steering wheel compared to EPS [9; 10; 11; 12; 13; 14]. Major automobile manufacturers and suppliers around the world have conducted in-depth research on wire-controlled steering systems, and internationally renowned suppliers such as TRW (TRW Automotive Holdings Corp), Delphi, and ZF have manufactured physical prototypes for experimental research. International famous automobile manufacturers such as Mercedes Benz, BMW, General Motors, etc., exhibited a concept car with a steer-by-wire system. In the late 1960s, Kasselmann in Germany s started to develop steering-by-wire system. In 1990s, Benz initiated its study in front- wheel-steering study, and applied the steer by wire system on Concept Vehicle \"F400 Carving\". In 2000, BMW applied steering by wire in Concept Vehicle \"BMW Z22\", and the steering angle was reduced to 160 degrees. In 2013, Infinity Q50 applied steer-by -wire technology, in which two motors and three inter-monitored ECU were utilized to realize steering. In 2017, Schneider in USA developed steering-by-wire system composed of a \"silent steering wheel system\" and \"on-demand steering system\". At present, the research on the wire-controlled-steering system in China is gradually moving from theory to practice, and some progress has been made [15]. The wire-controlled-steering system is divided into three parts: the steering wheel module, the steering execution module, and central control unit (ECU) [16]. The steering wheel module includes components such as the steering wheel torque, angle sensor, road sensing motor, and its reducer [17]; The steering execution module includes components such as the linear displacement sensor, angle sensor, steering motor, and its deceleration mechanism; In addition, the wire-controlled-steering system also includes components such as a steering controller and power supply [18]. The steering wheel module (i.e., steering wheel) is used to receive the driver's steering control; The steering wheel torque sensor and angle sensor are used to collect the torque, angle, and speed input by the driver through the steering wheel; The road sensing motor and its reducer provide the driver with road sensing information and output the return torque of the steering wheel. Figure 1: **(left)** The development of automotive steering system; **(right)** Concept of steering by wire. The steering execution module includes various sensors, and the linear displacement sensor is used to collect the linear displacement signal of the steering actuator and convert it into a front wheel angle signal; The angle sensor is used to collect the angle information of the steering wheel; The steering motor and its deceleration mechanism are used to overcome steering resistance and drive the steering system to rotate through the corresponding angle; The gear rack steering gear is used to receive and amplify the output torque of the steering actuator motor, driving the steering wheel to turn. The steering controller consists of multiple controllers. The steering wheel module controller collects relevant signals from the steering wheel module, receives target return torque signals, and sends control signals to the road sensing motor; The steering execution module controller is responsible for collecting relevant signals from the steering execution module, receiving target steering wheel angle signals, and sending control signals to the steering motor [19]. The wire-controlled-steering system shares a battery power supply with other electrical equipment in the vehicle.