Innolux's intelligent steer-by-wire solution makes cars smarter and safer

Figure 3-2 Schematic diagram of HWA torque closed-loop algorithm

3.3 Advanced functions of steer-by-wire

► Driving feel customization:

Compared with traditional EPS, SBW removes the intermediate shaft mechanical connection and uses a torque closed-loop algorithm to track the reference hand force, so the driving feel style can be flexibly designed. Compared with traditional EPS, which usually only has several styles such as comfort, standard, and sports, SBW has more performance and can even be customized according to the driver's preferences.

►Foldable steering wheel:

The adjustable range of traditional EPS steering wheels is very limited, so even in autonomous driving (such as APA/TJP/HWP, etc.), the steering wheel will continue to turn. After SBW removes the mechanical connection, the driver can choose to fold the steering wheel in the autonomous driving scenario, freeing up more cockpit space for rest, entertainment or work.

►Variable Steering Ratio:

The variable steering ratio function can take into account flexibility under low-speed conditions and stability under high-speed conditions, or can adjust the steering sensitivity of the steering wheel in the On-Center and Off-Center ranges. Due to the rigid mechanical connection of traditional EPS, it is necessary to change the mechanical structure to achieve a variable steering ratio, such as the rack and pinion transmission structure and the steering column structure. The structure and control are complex and the cost is high. For SBW, the variable steering ratio can be achieved through software algorithms, which has great flexibility and can be flexibly defined within a safe range. The optimal driving experience can be achieved for different scenarios, such as racing mode, comfort mode, sports mode, etc.

►Automatic Emergency Steering:

Automatic Emergency Steering (AES) is a function that can effectively avoid vehicle collisions on open roads. When implementing the AES function, the traditional EPS requires the steering wheel to quickly turn an angle in a very short time, and the driver's hands are usually still touching the steering wheel at this time, so it is easy for the AES function to conflict with the driver's control, and even cause the driver to panic. However, for the SBW system, when the automatic emergency steering function is activated, the task of emergency collision avoidance can be completed in a very short time without controlling the steering wheel, which is safer.

►Road interference suppression:

The steer-by-wire (SBW) system removes the mechanical connection while also cutting off the path of noise from the tires to the driver, thereby better suppressing invalid interference signals from the road, reducing mechanical noise, making the cockpit quieter, and effectively improving the driving experience.

►Infotainment features:

As car cockpits become more and more intelligent, they have become the second resting space for many consumers, with more and more infotainment functions. After removing the mechanical connection of the SBW system, the steering wheel can work as an actuator alone, so it can be used to link with the smart cockpit and used as a gaming steering wheel, and supports functions such as force feedback and vibration reminders.

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summary

线控转向（SBW）技术相比传统的EPS具有更高的技术壁垒，开发难度更大、开发成本更高，但是线控转向（SBW）技术能够支持L4级以上的自动驾驶功能，并且能够为汽车带来很多新的功能，显著提升驾驶体验，因此是汽车转向系统发展的必然趋势。

With the continuous development of wire control technology, steer-by-wire (SBW) technology is becoming more and more mature. Mainstream steering suppliers such as Bosch, ZF, Nexteer, and Mando have completed the development of SBW products and are expected to complete mass production before 2025. Domestic parts companies started later than international mainstream suppliers, but are catching up quickly under the impetus of national strategies. Innovative T-SBW solutions make cars smarter, safer, and more fun to drive, and can help customers create products that are more popular with consumers.