The Revolution of Chassis: A Look at Great Wall Motor’s Line-Control Chassis

In the era of gasoline cars, the three key components of a car are undoubtedly the engine, gearbox, and chassis. In the era of electric cars, these have become the electric motor, battery, and chassis. Therefore, regardless of the driving form, chassis is always an important part of a car.

With regards to autonomous driving, more and more people are focusing on the perception and decision-making sides of things, such as radars and cameras all over the body and the high-performance autonomous driving chips. Great Wall Motor believes that as the execution end of autonomous driving, only by closed-loop execution of perception, decision-making, and implementation can better autonomous driving products be made.

Therefore, it is time for the chassis of the car to undergo a revolution.

Yesterday, Great Wall Motor held a public class titled “Great Wall Coffee Intelligent 2.0 Line-Control Chassis.” Let’s take a look at what hardcore technology Great Wall Motor shared with us in this class.

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What is Line-Control Chassis?

When it comes to the concept of “line-control chassis,” it is certainly necessary to make a comparison with the traditional chassis structure. In a traditional chassis, the execution mechanisms of steering, braking, throttle, shifting, and suspension are all connected through mechanical structures to execute the operations of the driver through components such as the steering wheel, pedals, and gearshift.

On the line-control chassis, these execution mechanisms are connected through electronic signal transmission orders while ensuring safety redundancy. Compared with traditional chassis, the line-control chassis saves the cost and space of mechanical structures, improves the response of the driver, and achieves the “decoupling of human and car” required for future autonomous driving.# The core technology of Great Wall Motors Intelligent Drive-By-Wire Chassis

Sun Huiyun, a senior engineer in charge of the development of drive-by-wire chassis at Great Wall Motors, mentioned in a public lecture: without drive-by-wire chassis, it is impossible to achieve autonomous driving. Therefore, the goal of the Great Wall Motors Intelligent Drive-By-Wire Chassis was to build a technical platform for autonomous driving of level 4 and above from the very beginning of its design.

The Core Technology of Great Wall Motors Intelligent Drive-By-Wire Chassis

Based on the new GEEP 4.0 architecture, the Great Wall Motors Intelligent Drive-By-Wire Chassis integrates five core systems: drive-by-wire steering, drive-by-wire braking, drive-by-wire shifting, drive-by-wire throttle, and drive-by-wire suspension.

Sun Xidong, a senior engineer involved in platform architecture at Great Wall Motors, mentioned that all five core systems are indispensable to achieve the full functionality of the Intelligent Drive-By-Wire Chassis. Among them, the most crucial and challenging systems to conquer are the drive-by-wire braking and steering systems.

Great Wall Motors’ drive-by-wire braking system uses the four-wheel EMB electronic mechanical drive-by-wire braking system. Unlike traditional braking systems, the EMB system directly uses a motor to clamp the friction plate, replacing the four major components of ESP, iBooster, hydraulic pipelines, and EPB.

The electronic mechanical drive-by-wire braking can make the brake response faster, stopping at 100km/h, reducing the braking distance by 4.8m. At the same time, it also improves the efficiency of regenerative braking, increasing the range over 20%.

Overall, the Great Wall Motors drive-by-wire braking system has quicker response, higher efficiency, and better weight reduction with the four-in-one mechanical components.

The Great Wall Motors drive-by-wire steering system completely discards the transmission shaft between the steering wheel and the steering mechanism and transmits signals through the CANFD bus. Starting from a higher level of autonomous driving scenarios, the steering wheel after scrapping the transmission shaft will also support folding. It truly realizes the decoupling of human and car, defining future autonomous driving vehicles as “mobile spaces.”

To meet the needs of more users, the Great Wall Motor’s drive-by-wire steering system can achieve dynamic adjustment within the range of variable gear ratios from 9 to 16, and adopts a simulated tactile unit for real road feel, retaining the pleasure of driving.

Advancing Safety and Innovation Together

One of the most challenging aspects of drive-by-wire chassis and powertrain systems is safety. Many researchers find it difficult to overcome this bottleneck. So, how did Great Wall Motor’s Intelligent Drive-by-Wire Chassis achieve it?

Great Wall Motor’s drive-by-wire chassis employs a three-redundancy system to provide multiple safety guarantees, especially for the drive-by-wire steering and drive-by-wire powertrain systems related to driving safety. The power supply, sensors, controllers, and actuators are all designed with a three-redundant backup to ensure that the system’s functional safety level remains at the highest automotive safety integrity level, ASIL D.

In fact, the functional safety level of automatic driving systems on the market today is generally at the ASIL C level, whereas the requirements for Great Wall Motor’s Intelligent Drive-by-Wire Chassis system are to achieve the highest ASIL D level. This means that the system failure rate is 1% of ASIL C level, which is 100 times safer than the safest car currently available.

In addition to the three-redundancy system, innovation is also key to safety. Apart from the three-redundant system, Great Wall Motor’s drive-by-wire chassis also has a set of cross-system redundancies. In an open class, Sun Xidong, a senior engineer of platform architecture at Great Wall Motor, gave an example:

• When the steering system fails, the drive-by-wire chassis system can achieve steering by braking a single wheel or one side of the vehicle;
• When the powertrain fails, the drive-by-wire chassis system can achieve vehicle deceleration by increasing the energy recovery intensity.

In other words, based on the architecture of Great Wall Motor’s GEEP 4.0, the drive-by-wire chassis system can flexibly mobilize each core system hardware to achieve cross-system redundancy and further enhance safety.

With a functional safety level like ASIL D, combined with three-redundancy backups and cross-system redundancies, Great Wall Motor has ensured the “safety” of its drive-by-wire chassis through “innovation”.

Why is it called the “Intelligent” Drive-by-Wire Chassis?In the public lecture, Sun Xidong, Senior Engineer of Platform Architecture at Great Wall Motors, specially shared the meaning of “wisdom”. Due to the decoupling of people and cars, the Great Wall Motors intelligent line-controlled chassis can form various control loops on its own depending on the central control unit and vehicle sensors. The central processing unit autonomously thinks or coordinates control based on input signals from the human body as the reference for the whole vehicle, and decomposes the actions of various systems to achieve autonomous coordinated control at the whole vehicle level.

In addition, the Great Wall Motors intelligent line-controlled chassis can also provide customized driving style, cloud synchronization of driving experience, etc. After being bound to a personal account, one can use their own customized driving style on different models and vehicles. At the same time, in order to meet the demand for software upgrade, the Great Wall intelligent line-controlled chassis reserves sufficient hardware capabilities for future OTA upgrades to achieve functional iteration and evolution.

Finally

Just like the gear shifters of bicycles, from the original cable shifters to today’s electronic line-controlled shifters; the steering and braking mechanisms of airplanes, from the original mechanical linkages and hydraulic assist to today’s line-controlled systems. Bicycles are for coping with stronger competitive scenarios and reducing the vehicle’s wiring harness. Airplanes aim for more efficient and effortless control and more precise control by auto-piloting systems.

Every aspect of our daily life is undergoing a development process from mechanical transmission to electronic signal transmission, which is the hallmark of the digital and intelligent era.

Cars are no exception. The development goals that cars pursue today include higher-level autonomous driving, more diverse modes of transportation, and better driving and riding performance. All of these are inseparable from the development of line-controlled chassis.

It is not difficult to see that the future belongs to line control. The Great Wall Motors’ intelligent line-controlled chassis technology will accelerate this “chassis revolution”.

Easter Egg

Finally, I would like to mention an Easter egg I found in this “Great Wall Motor Coffee Intelligent 2.0 Line-Control Chassis Public Lecture” picture.

In this picture, it is not difficult to find a design element that looks like a “barcode”, which seems cluttered but apparently has a certain pattern.“`

If we treat the black boxes as separators, there are 7 groups of color blocks, and each group consists of green and purple. If we take green as “0” and purple as “1”, then the code of the first group of color blocks is “01000111”.

I originally thought this was some kind of special programming language, so I went to Baidu to search. Unexpectedly…

It turns out that this is a set of ASCII codes, and “01000111” represents the letter G. When I converted all the color blocks, the final result was “GREATWALL 长城”.

I have to say that “geeky little warmth” always surprises me.
“`

This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email bd@42how.com.