What are the most important factors that affect the final implementation of autonomous driving? What about brake-by-wire control?

SIIC Research Institute released the "2020 Automotive Wire-Control Chassis Industry Research Report", analyzing and studying the current status and suppliers of the wire-control chassis industry.

The wire-controlled chassis makes it feasible for self-driving cars to eliminate the accelerator pedal, brake pedal and steering wheel. Its technical maturity affects the final implementation of self-driving.

The core elements of the drive-by-wire chassis include: drive-by-wire throttle, drive-by-wire shifting, drive-by-wire suspension, drive-by-wire steering, and drive-by-wire braking. Driving, braking, and steering are considered to be the key factors affecting vehicle driving.

Figure: Development history of drive, braking and steering

Throttle-by-wire is currently the preferred configuration for passenger cars, especially for vehicles with ACC and TCS functions, where throttle-by-wire has become a "standard configuration". Due to the immaturity of early technologies, the use experience of brake-by-wire and steering-by-wire is not as good as that of traditional mechanical systems. In addition, the on-board computer regulates and controls the actuators, and it is difficult to clarify the responsibility. All these factors have hindered its popularization and promotion in the market. The rapid development of intelligent connected vehicles in recent years has brought new vitality to the technology of brake-by-wire and steering-by-wire.
 

Brake-by-wire: Bosch, Continental, and ZF are leading the industry, while domestic companies such as Bethel, Nason Electronics, and Top Group are trying to catch up

Over the past 100 years, the automotive braking system has evolved from mechanical to hydraulic to electronic (ABS/ESC). In the future, for L3 and above autonomous driving vehicles, the response time of the braking system is particularly important. Braking by wire has a faster response and is an important guarantee for achieving autonomous driving safety.

Figure: Development history of automobile brakes

There are two types of brake-by-wire systems: EHB: ElectroHydraulic Brake (hydraulic brake-by-wire) and EMB: ElectroMechanical Brake (mechanical brake-by-wire). EHB can be divided into One-Box and Two-Box solutions depending on whether it is integrated with ABS/ESP.

Table: Comparison of One-Box and Two-Box product solutions

Among them, the One-box solution has become mainstream:

The One-Box solution integrates ESP into EHB, so it needs to be based on mature ESP mass production experience. Due to its advantages in performance and cost, Bosch, Continental, and ZF are gradually increasing their investment in One-Box products.

Domestic suppliers with first-mover advantage are expected to achieve domestic substitution. Bethel is the first domestic supplier to develop One-Box products. Its WCBS products are expected to be mass-produced in 2020, which is not much different from the mass production time of foreign companies such as Bosch. In addition, WCBS integrates dual-control EPB, which has certain cost-effectiveness advantages.

Table: Domestic and overseas brake-by-wire product solutions

Steer-by-wire: Intelligence drives industry development, but commercialization is hampered

Since the development of steer-by-wire, the only brand with mass production solutions is Infiniti. In 2014, the Infiniti Q50 equipped with DAS steer-by-wire was unveiled, and its steer-by-wire solution came from KYB. However, in July 2016, Dongfeng Motor and Nissan announced the recall of Infiniti Q50 and domestically produced Q50L, totaling 6,840 vehicles, due to safety hazards of steer-by-wire. Currently, Infiniti has four models equipped with DAS, and the solutions are all from KYB.

Figure: Infiniti models equipped with wire-controlled steering

From the perspective of the global competition landscape, international giants such as Bosch, ZF, JTEKT, NSK, and Nexteer have mature steer-by-wire products and technologies, but still encounter bottlenecks in commercialization.

Table: Domestic and overseas steer-by-wire product solutions

In 2020, the mass production of L3 autonomous driving will drive the commercialization of wire control system products. Foreign companies that are the first to enter the Chinese market will have a first-mover advantage. Looking at the domestic market, there are very few Chinese companies that have made achievements in wire control technology, and their scale is relatively small. However, due to the importance of wire control chassis, it still attracts capital and giants to enter. Nason completed financing of 400 million yuan in 2019. And there are rumors that Huawei will enter the field of wire control chassis.