Gasgoo Automotive Research Institute: The Spring of Intelligent Chassis is Coming

With the development of intelligent driving , chassis wire control has become an inevitable trend as the core technology of the execution layer. Especially with the accelerated popularization of high-level autonomous driving represented by NOA function , the intelligent chassis industry will usher in unprecedented development opportunities.

Based on this background, Gasgoo Automotive Research Institute has conducted research and analysis on the intelligent chassis industry from three dimensions: industry development overview, market analysis, and future development trends, for reference by relevant parties. Part of this report is as follows:

Industry Development Overview

The wire-controlled chassis technology transforms the five key parts of brake, throttle, steering, gear and suspension from the traditional integral hard connection to a wire-controlled design connected by wires, and controls the vehicle chassis actuators through electrical signals to achieve the functions of acceleration, braking, steering and suspension adjustment. The core feature of the intelligent wire-controlled chassis is "human-machine decoupling", that is, decoupling the actuator from the steering wheel and brake pedal controlled by the driver.

The intelligent chassis consists of five subsystems: brake-by-wire, steering-by-wire, suspension-by-wire, drive-by-wire, and shift-by-wire. Brake-by-wire and steering-by-wire are the core links, and the technology is the most complex. They are the key to the future development of intelligent chassis components . Suspension-by-wire is accelerating its application in vehicles. Throttle-by-wire and shift-by-wire technologies are already very mature and widely used.

Wire control can achieve active, precise and rapid braking in the Y direction, meeting the braking requirements of smart cars . Wire control braking mainly includes two technical routes: wire hydraulic brake system (EHB) and electronic mechanical brake system (EMB). Currently, EHB is the mainstream.

The EHB Two-box solution is the first to be launched and has the advantage of brake redundancy; the EHB One-box solution has cost and performance advantages. From January to April 2024, the penetration rate of wire-controlled brakes in domestic passenger cars has reached 42.7%, of which the One-box solution accounts for 61.2%, making it the mainstream solution.

Compared with EHB, EMB completely abandons hydraulic components and uses the motor to directly drive the caliper to complete the braking. Each wheel corresponds to a set of brake actuators, and each set of actuators includes a torque motor , a brake housing and a brake caliper block. With higher braking power, faster response speed and more precise braking control, EMB is expected to become one of the ultimate forms of wire control braking, but it currently faces technical and mass production difficulties, and it will take some time before it can be mass-produced.

In addition, the industry has also proposed a hybrid braking transition solution HBBW, which uses EHB braking on the front wheels and EMB braking on the rear wheels. This solution can not only meet the redundancy requirements of L3 regulations, but also meet cost considerations, and is expected to become a transition product from EHB to EMB. Currently, mainstream players in the industry such as Continental, ZF, Brembo, Betheli, and Liker Technology are accelerating the implementation of the front wet and rear dry and EMB braking solutions.

SBW, the steer-by-wire technology, is developed based on the electronic power steering ESP. It eliminates the mechanical intermediate shaft, realizes the information transmission of steering by electrical signals, and realizes intelligent vehicle steering by control algorithms. It is a key technology for realizing high-level autonomous driving. SBW realizes the physical decoupling between the steering wheel and the steering system, and can theoretically achieve any transmission ratio , thereby greatly improving the intelligence and controllability of the car. However, due to the constraints of reliability and high cost, the full-steer-by-wire technology is currently rarely mass-produced on vehicles, and rear-wheel steer-by-wire has been mass-produced and launched on some mid-to-high-end models.

The wire-controlled suspension adjusts the stiffness and damping of the vehicle in the Z direction through the ECU to control the suspension actuator , so that the suspension system is always in the best vibration reduction state to ensure the comfort and controllability of the vehicle. Air suspension is the main form of wire-controlled suspension at present. The biggest difference from the traditional suspension system is the upgrade of elastic elements, and the addition of electronic control systems and air pumps and other components, which gives the suspension intelligent dynamic adjustment function and a more complex structure. At present, the air suspension system of passenger cars mostly adopts the "air spring + CDC electronically controlled shock absorber" solution.

With the trend of intelligence, air suspension has evolved into a "magic carpet suspension" with a road preview function, which can combine the vehicle perception system or cloud data to scan the road conditions ahead in advance and actively adjust the suspension. At present, the price of models equipped with air suspension has dropped to 250,000 yuan. With the decline in domestic costs and the demand for consumption upgrades, air suspension will accelerate the process of vehicle installation.

The chassis domain controller is a whole system consisting of domain master hardware , operating system, algorithm and application software . Under the "central integration + domain controller" architecture, the chassis domain controller plays the role of the car's "cerebellum" to achieve integrated control of the car in the longitudinal, lateral and vertical directions.

Chassis domain controllers have high development barriers. Their related components mainly involve several modules such as suspension, braking, and steering. They are difficult to integrate and are highly related to vehicle driving safety. It is necessary to solve the software interoperability problem between suppliers of components with different functions. The control algorithm development is difficult and has a long cycle. Currently, Tier 1 focuses on the development of single/multiple subsystem (domain) controllers of chassis subsystems. There are not many manufacturers with mature chassis domain controller mass production solutions. Domestic manufacturers have the opportunity to overtake others by virtue of their advantages in development coordination and response speed.

Market Analysis

The brake-by-wire market will usher in explosive growth with the popularization of L2+ and above intelligent driving, and the penetration rate is expected to reach 50% in 2025. At present, foreign capital still dominates my country's brake-by-wire market, but with the accelerated penetration of intelligentization of domestic brands, the market share of local suppliers will gradually increase. Domestic manufacturers Betheli and Fudi Power have both exceeded 10% of the market share, and manufacturers such as Liker Technology, Nason Electronics, and Qiangu Technology have begun rapid mass production.

The steer-by-wire industry is in its infancy, and it is expected that the penetration rate of steer-by-wire in China will reach 5% by 2025. Overseas companies such as Bosch , JTEKT, and ZF have first-mover advantages. Domestic manufacturers have a large gap due to their late entry. Most companies are in the R&D stage, among which Nexteer has achieved mass production.

The wire-controlled suspension market is in a rapid development stage, and the penetration rate is expected to reach 13% in 2025. At present, domestic companies Konghui Technology and Baolong Technology have occupied a dominant position in the market, and domestic substitution is accelerating.

As for car companies, OEMs represented by NIO, Ideal, Great Wall, BYD , Geely, and Huawei are actively deploying intelligent wire-controlled chassis and chassis domain control technologies, some of which have been put into mass production.

As for suppliers, with the trend of modularization of wire-controlled execution systems and integration of chassis computing and control, suppliers that simultaneously deploy wire-controlled braking, steering, and chassis domain control can provide customers with integrated wire-controlled chassis solutions and are expected to seize the initiative in the commercialization of wire-controlled chassis.