Integrated Intelligent Chassis: Concepts, Design Principles, and Standardization Initiative

The automotive industry is undergoing its most profound transformation since its inception. The shift from the mechanical age to the current wave of electrification and intelligence is accelerating unprecedentedly across the industry, particularly within China. The advent of integrated intelligent chassis, also known as skateboard chassis, offers a revolutionary approach to vehicle manufacturing and a novel solution for mobile energy carriers. It empowers the industry to evade cutthroat competition and achieve scene-oriented, intelligent, and personalized development.

Recently, Integrated Intelligent Chassis: Concepts, Design Principles, and Standardization Initiative (the “Initiative”) was released. The document was prepared by Contemporary Amperex Intelligence Technology (Shanghai) Limited (CAIT-SH) with guidance from the China Society of Automotive Engineers (China-SAE). The Initiative elaborates on the industry context and market demand that has driven the emergence of integrated intelligent chassis, defines the design principles for integrated intelligent chassis, and proposes standardized interfaces to facilitate their development.

The document is organized into five chapters, which are summarized below. A link to the complete document is attached at the end. We welcome everyone to join the discussion and participate in the standardization efforts for integrated intelligent chassis.

Chapter 1: Advent of Skateboard Chassis: An Inevitable Milestone in the Evolution of Intelligent Electric Vehicles

In 2023, China's new energy passenger vehicle sales surpassed 7 million units, with a total stock exceeding 18 million units. Both the production volume and vehicle stock represent over half of the global market. According to data from the China Association of Automobile Manufacturers and the Japan Automobile Manufacturers Association, China surpassed Japan in the first half of 2023, becoming the world's largest automotive exporter. As Premier Li Qiang emphasized at a State Council meeting, strengthening the research and development of key technologies such as power battery systems, new chassis architectures, intelligent driving systems, and other important domains is crucial for enhancing the independent and controllable capabilities and green development of the entire industry chain. This underscores a significant opportunity for new chassis architectures, specifically integrated intelligent chassis.

Meanwhile, automobiles are evolving beyond mere transportation. They are becoming crucial links connecting life and work as “mobile third spaces.” The age of intelligence is reshaping the automotive industry's value chain.

Electrification has given rise to proven, stable chassis products. Needs for personalization have prompted automobile manufacturers to focus more on developing intelligent cockpits and autonomous driving, with computing power gradually outweighing horsepower. The increasing maturity of “by-wire” technology provides the technical foundation for decoupling vehicle bodies from chassis, while carbon peak and neutrality goals call for low-carbon solutions and circular economy practices. To address the industry's issue of “reinventing the wheel,” the standardization and sharing of automotive platforms and components between enterprises have become inevitable.

In the future development of intelligent vehicles, vehicle bodies and chassis will be completely decoupled, developed in parallel, and iterate asynchronously. Skateboard chassis will help mobility layers solidify their electrification foundation, enabling them to focus precisely and develop efficiently to meet intelligent and scenario-based requirements, building core competitiveness for the “second half” of the game of intelligence.

Chapter 2: Definition and Industry Value of Intelligent Skateboard Chassis

General Motors introduced the concept of decoupling the upper and lower vehicle bodies in a pioneering concept vehicle over two decades ago. For over two decades, this vision has been a guiding light for skateboard chassis technology. The skateboard chassis concept has evolved into reality through continuous exploration and innovation by industry pioneers, and its commercial applications are emerging.

An intelligent skateboard chassis is a self-contained, electrically powered, drivable minimal vehicle unit capable of a degree of autonomous control over its movement. It comprises, at minimum, a chassis or other load-bearing structure, an energy system, a power system, a transmission system, a driving system, a steering system, and a braking system, characterized by a flat or near-flat form factor. In response to commands from the driver or an autonomous driving system, the chassis makes active corrections and provides feedback based on the current vehicle state. In essence, the intelligent skateboard chassis is an integrated control unit that supports intelligent and even autonomous driving, combining energy and vehicle motion capabilities. The three key attributes defining the intelligent skateboard chassis are electrification, integration, and intelligence.

Professor Zhang Junzhi, Chairman of the Intelligent Chassis Branch of the China-SAE and Professor at Tsinghua University, provided insightful clarification on the relationship between skateboard chassis and intelligent chassis. He noted that the skateboard chassis represents a form of the intelligent chassis, a distinct business model, and a significant emerging force, signifying a new product, a new model, and a new category.

By enabling the separation of the upper and lower vehicle bodies innovatively, the intelligent skateboard chassis disrupts the traditional automotive industry's vertically sequential process of integration. Through parallel development and asynchronous iteration of upper and lower vehicle bodies, it significantly enhances manufacturing efficiency. Platform sharing across the industry breaks down the traditional closed loops of “reinventing the wheel,” ushering in a new era of standardized vehicle manufacturing to foster a thriving future mobility ecosystem.

From an industrial chain perspective, the intelligent skateboard chassis, representing the lower vehicle body, serves as a shared and relatively standardized platform. Sharing can substantially reduce research and development costs. The intelligent skateboard chassis also maximizes the vehicle's value throughout the vehicle's lifecycle. Last but not least, the intelligent skateboard chassis will benefit the establishment of automotive industries in smaller countries by adapting to the specific needs of different countries.

Chapter 3: Design Requirements for the Integrated Intelligent Chassis

1. Internal Integration: Solidifying the Electrification Foundation and Enhancing Industry Efficiency

Internal integration is the paramount design requirement for the integrated intelligent chassis. This involves highly compact physical integration, incorporating as many systems and components as possible within the chassis while maintaining a completely flat chassis design to maximize design flexibility for the upper body. Furthermore, high integration reduces chassis weight and improves battery pack assembly efficiency. Generally, internal integration in an integrated intelligent chassis encompasses mechanical, energy, and control integration.

Mechanical integration involves the integration of the energy storage unit, the electric drive system, the steering, braking, and suspension systems, high- and low-voltage power distribution, and the thermal management system with the chassis.

2. Decoupling of Upper and Lower Bodies: Asynchronous Development to Accelerate Transformation towards Better Intelligence

Decoupling of upper and lower vehicle bodies involves mechanical, electronic, electrical, and software decoupling.

Mechanical decoupling relies heavily on “by-wire” technology, a crucial enabler of electrification and intelligence in the global automotive industry and a key pathway toward upper and lower body decoupling. The key includes brake-by-wire and steer-by-wire. Brake-by-wire systems offer advantages such as rapid response, low energy consumption, and precise braking force control. In conjunction with an electronic brake pedal, it enables complete decoupling of upper and lower bodies. It supports functions such as brake booster, electronic stability control (ESC), comfort regenerative braking system (CRBS), value-added functions (VAFs), distributed traction control system (dTCS), and electronic parking brake. This meets the stringent response time requirements of advanced emergency braking (AEB) systems while allowing for customization of pedal feel.

By eliminating all mechanical connections between the steering wheel and the wheels, steer-by-wire technology enhances maneuverability and stability while unlocking fascinating possibilities for intelligent driving and cockpit design, providing unprecedented driving experiences and vehicle space utilization.

As software-defined vehicles become increasingly recognized, the separation of software from hardware, coupled with the upward migration of control functions and standardization of underlying hardware, enables a service-oriented architecture (SOA) across the entire vehicle. The vehicle's electronic and electrical architecture is evolving from the dominant multi-domain fusion architecture to a centralized computing architecture featuring decoupled upper and lower vehicle bodies and integrated driving control. Standardized communication interfaces enable the decoupling of the system control and computing center in the upper body (intelligent space) from the motion and energy center in the lower body (integrated intelligent chassis), allowing adaptability to diverse application scenarios.

Software decoupling involves control and service decoupling. Through the extensive integration of common modules, the integrated intelligent chassis features a universal control system software architecture adaptable to diverse vehicle requirements, allowing for high scalability and universality. Control necessitates the standardization of interfaces between the integrated intelligent chassis and external domain control modules. Following a functional development strategy, the modules are developed to realize complex functions and exposed to external systems through standardized interfaces. Inter-service communication leverages standardized middleware such as SOME/IP and DDS.

3. Openness: Fostering Industry Collaboration and a Thriving Future Mobility Ecosystem

From a hardware perspective, the integrated intelligent chassis serves as an independent mobile platform, enabling industry players to create vehicles working in diverse scenarios. More broadly, it should function as an open, inclusive, and integrative platform connecting various segments of the industry.

To accommodate personalization needs and diverse application scenarios, the chassis platform must allow for software and data openness, functioning as an integral part of the broader Internet of Vehicles (IoV) ecosystem rather than a closed system.

By integrating and managing various components (both intelligent and non-intelligent), the integrated intelligent chassis provides unified hardware identification information to identify and cryptographically protect data generated by its subsystems. Combined with vehicle identification (VID) technology, it is possible to create a large data application and sharing platform for chassis data accessible to third-party developers while ensuring data authenticity and integrity.

Chapter 4: Interface Standardization Drives the Advancement of Intelligent Skateboard Chassis

In the future, highly intelligent vehicles must meet ever-increasing needs for personalization, necessitating total hardware and software decoupling through interface standardization. The evolution of mobile phones and computers has provided successful examples of such standardization.

Faced with fast-growing intelligence capabilities, the automotive industry should draw on the best practices of the computer and mobile phone industries to reach a consensus on standardization. The intelligent skateboard chassis possesses inherent potential for standardization. Upstream and downstream companies can leverage it as a starting point and implementation platform for interface standardization to actively advance the industry's standardization efforts, facilitate the decoupling of upper and lower bodies and the decoupling software and hardware, and establish standardized intelligent skateboard chassis as the universal foundation for intelligent vehicles.

This document explains standardized definitions for mechanical, electrical, and software interfaces on the intelligent skateboard chassis to the upper vehicle body, and plans an initiative for standardization of these interfaces.

Mechanical interfaces encompass joining and sealing upper and lower vehicle bodies.

Standardization of mechanical interfaces and quick-change technology for hardware will evolve in concert with intelligent skateboard chassis, progressively implemented in phases and across various scenarios, and enable decoupling, ready replacement, and ultimately free interchangeability of upper and lower bodies.

Standardized high-voltage interfaces for the intelligent skateboard chassis include a combined AC/DC charging inlet, a DC high-voltage connector, and an AC high-voltage connector. Standardized low-voltage interfaces include 12V power connections and signal connections between the upper and lower vehicle bodies.

To support the decoupled development of the upper and lower vehicle bodies, software interface standardization is crucial for communication between the chassis and external domain control modules. This enables a universal system software architecture that can flexibly adapt to different vehicle models. Software interface standardization involves communication, control, and service interfaces. Software for upper and lower bodies interacts through standardized interfaces, employing a service-oriented architecture (SOA). This involves standardizing the encapsulation of capabilities of the intelligent skateboard chassis and exposing them to external models via standardized interfaces to enable service decoupling, independent development, and unified integration.

Chapter 5: Envisioning Future Mobility Based on Intelligent Skateboard Chassis

In the coming era of free mobility, vehicles are expected to evolve into “third living spaces” and even all-scenario spaces. An automobile will transform into two distinct components: an intelligent upper body focused on user experience with spatial attributes and an intelligent chassis responsible for mobility with mobility attributes. The upper body will primarily serve as an intelligent living space, integrating the intelligent cockpit and autonomous driving systems. It will be the primary interaction and experience space for consumers, powered by a high-performance computing center that enables features such as AI assistants (virtual humans) and vehicle-cloud interactions. The lower body will act as the intelligent mobile carrier. The highly integrated chassis efficiently manages energy and motion, realizing mobility for the upper body.

The intelligent skateboard chassis forms the foundation for future free-mobility spaces. The resulting separation of intelligent spaces from intelligent chassis will likely drive further specialization within the industry supply chain and, thus, the overall efficiency and competitiveness. Driven by an approach centering on user experiences, collaborative models across the supply chain will also transform.

In terms of business models, intelligent cockpits and autonomous driving will be crucial in reshaping the industry landscape and gaining market dominance. New business models and players will emerge, with two predominant models: user-centric services and vehicle-centric services. The intelligent skateboard chassis will provide essential support for both. Batteries, chassis, and upper bodies can be independently managed as assets to maximize their utilization.

The future automotive industry will feature diverse business models centered around end-users (2B/2C). Key elements include the intelligent space (upper body), the intelligent skateboard chassis (lower body), and operators (including OEMs and platform operators) focused on end-users (C-end and B-end customers).