Development trend of automobile steering-by-wire technology

Zheneng Automobile is currently working with the owner of the automobile museum to make an industry technical report and selects some basic information for reference.

01. Steering-by-wire technology route

Steer-by-wire technology is an innovative electronic steering system that uses electronic components such as sensors, motors, and controllers to replace traditional mechanical components such as steering columns, shafts, and gears, enabling driving without a physical connection between the steering wheel and wheels. .

The introduction of this technology brings a new experience and convenience to drivers. Through the operation of algorithms, electronic devices and actuators, the steer-by-wire system can simulate real road feel and provide precise steering feedback to the driver. Not only that, it can adapt to different types of vehicles, from sports cars to luxury sedans, delivering outstanding performance and comfort. The variable transmission ratio design further enhances the vehicle's handling and comfort.

Compared with traditional steering systems, steer-by-wire technology has many advantages:

● Variable transmission ratio: Corresponding to the same tire rotation angle, the ordinary traditional steering wheel can rotate 180 degrees, while the steer-by-wire steering may only need to rotate 40 degrees or not at all.

● More precise and sensitive: It can provide more precise and sensitive steering, as well as customizable steering style. Adjusting the feedback damping of the steering road-sensing motor can give the driver different damping feelings.

● Platformization: For left and right-hand drive models, the steering actuator can be shared to improve platform commonality and shorten the development time of overseas and domestic platform models.

● Can be used for assisted driving functions: when there is no manual steering operation, the steering command can be sent through the automatic driving controller to directly control the drive motor to execute the steering command.

Currently, many domestic and foreign automobile manufacturers and technology providers are actively developing and promoting steer-by-wire technology. For example, Toyota has applied OMG (One Motion Grip) technology in its bZ4x model to achieve mechanical separation of the steering wheel and steering execution system, providing drivers with an easier operating experience. In addition, Tesla also plans to use steer-by-wire technology in its new Model S and Model X models to further improve their driving performance and convenience.

In the steering-by-wire system, the controller detects the driver's intention through the torque and steering angle sensors on the steering wheel, analyzes and makes judgments based on vehicle speed, wheel speed and other information, and outputs steering control instructions to the front wheel steering motor ( Steering Motor) and Rear Road Wheel Motor (Rear Road Wheel Motor), thereby driving the steering mechanism to turn; at the same time, it can detect road resistance and feed the resistance back to the Torque Feedback Motor (Driver Feedback Motor) to simulate road resistance. to the driver. The system can also include backup sensors and redundancy measures to ensure that the steering system still functions properly in the event of a failure.

02. Tesla’s steering-by-wire system implementation plan

Tesla is expected to announce in the Q2 quarter of 2024 that it will use steering-by-wire technology with Yoke steering wheels in new Model S and Model X models.

Tesla plans to introduce a steer-by-wire system in the new Model S and Model X models in the second quarter of 2024, matching the Yoke steering wheel.

Tesla added steer-by-wire technology as it continues to seek to reduce vehicle parts to speed up production times. Traditional electric steering systems require connecting the steering column to the universal joint before installing the rack and pinion system, but using a steer-by-wire system can save manufacturing time.

One of the great advantages of steer-by-wire technology is that the steering wheel is no longer directly connected to the road, providing a smoother driving experience. This means there will be no vibration or pulling on the wheels on uneven roads, making driving safer, especially important for disabled or elderly drivers.

该先进的控制系统能够实时监测多个输入变量，以产生精确的转向比。这意味着驾驶员在低速急转弯时不需要频繁转动方向盘，例如在停车场中，理论上甚至可以完全消除手动转向的需求。

03. Technology from Toyota and other manufacturers

In addition to Tesla, Toyota has adopted Toyota OMG (One Motion Grip) technology in the 2022 bZ4x model. This advanced technology integrates steer-by-wire technology and a racer steering wheel to achieve mechanical separation of the steering wheel and the steering execution system.

Toyota OMG technology replaces the traditional mechanical structure through electrical signals and high-speed buses . It sets the steering wheel rotation angle to plus or minus 150°. It basically does not require changing hands to turn the wheel to complete the steering operation, which greatly reduces the driver's need to turn, turn around, and turn the wheel. The burden during operations such as warehousing is more suitable for the actual use scenario of the yoke-type steering wheel promoted by Toyota in the future.

According to Toyota's steering-by-wire technology patent, its steering-by-wire system consists of a steering torque actuator at the steering wheel position and a steering control actuator at the steering shaft position. Steering wheel torque and steering wheel angle signals are the core inputs of steering control. They are combined with the variable steering speed ratio function to calculate the target front wheel angle control variable and are sent to the angle feedback controller in the steering control actuator for precise control of the front wheels. angle and motor current. At the same time, the front wheel angle and motor current are returned to the steering wheel actuator as road surface information to generate steering feedback force.

Foreign Tier1 suppliers such as JETKT, Hitachi, Mobis, ZF and Nexteer already have mature steer-by-wire technology. Toyota and other foreign manufacturers have successively launched mass-produced models equipped with steer-by-wire systems, and Tesla is also developing a steer-by-wire system. It is expected that mid- to high-end models will generally adopt this technology in the future. Domestically, Baidu has launched a strategic cooperation with ZF to jointly develop wire control technology, and Weilai has also established its own steering electronic control development team. Judging from ZF’s former employees, they have formed an integrated team. It is foreseeable that steer-by-wire technology will become one of the hot spots for future automotive technological innovation, and together with technologies such as wheel motors and active hydraulic suspension, it will redefine the barriers to technological innovation.