Introduction to Huawei's self-developed HUAW ElxMotion body collaborative control system

The HUAW ElxMotion system is Huawei's self-developed intelligent body collaborative control system, which provides a longitudinal, lateral and vertical integrated collaborative control solution for new energy vehicles.

Torque Vectoring Control (TVC) is a feature of the HUAWEI xMotion system that targets the cornering characteristics of a vehicle. It dynamically senses the road surface when entering and exiting a curve and performs adaptive torque adjustment to help increase lateral force and reduce the risk of drifting. It can also further enhance the vehicle's maneuverability and safety, making the driving experience more secure.

Among experienced drivers, there is a saying that "front-wheel drive cars are prone to pushing the front, and rear-wheel drive cars are prone to drifting", especially in rainy and snowy weather, this phenomenon is more obvious. On the snow, a slight steering wheel may result in serious problems such as "inability to turn" and "drifting out of control".

In order to explore the root cause behind this problem, the editor specially opened the vehicle engineering textbook that had been dusty for many years. Now I will give you a little "hardcore" science popularization!

Let's start with the most important part of a vehicle, and the only part that comes into direct contact with the ground - the tire. As we all know, the tire itself is a rubber product, and the vehicle is able to move only by the friction of this rubber product. When it comes to friction, everything has a limit, and tires also have a friction limit, which corresponds to the famous "tire friction circle".

To summarize the "tire friction circle" in one sentence: there is a limit to the friction that a tire can provide. When the longitudinal force is large, the lateral force that can be provided will become smaller.

In rainy and snowy weather, it is really "misfortunes never come singly". The tire's grip limit will be reduced, and the lateral force that can be provided under the same driving force will be further reduced. At this time, for rear-wheel drive vehicles, since the rainy and snowy road surface reduces the tire's grip limit, and when the torque output is all on the rear axle, the lateral force that the rear wheels can provide will be limited. High throttle output will cause the tire's grip limit to be exceeded, and the rear tires will slip, resulting in "tail swing". Similarly, front wheel slippage of front-wheel drive vehicles will cause "head push".

Some smart friends may now be able to see the solution to the problem, which is to distribute the larger torque of a single axle to other axles! The TVC feature provided by our HUAWEI xMotion is developed based on this principle!

The TVC feature provided by HUAWEI xMotion can identify the potential risk of unexpected understeer or oversteer of the current vehicle based on high-real-time dynamic perception of the vehicle's status, and reduce the risk by adjusting the torque of the entire vehicle. This feature, as one of the key technologies of the Tuling chassis, is applied to the Wenjie M9 model.

The TVC function collects information to calculate the user's expected turning angle in real time and monitors the vehicle's driving status in real time. For example, when the vehicle oversteers, the rear-drive torque is intelligently reduced so that the rear wheels can better provide lateral force; at the same time, the reduced torque is transferred to the front drive to ensure that the vehicle's torque is not reduced. Overall, the risk of "tail drifting" is resolved while ensuring that the vehicle speed does not change significantly.

In our daily driving process, by dynamically adjusting the front and rear torque of the vehicle, the TVC function will distribute more torque to the rear wheels when the vehicle enters a corner, making the steering more agile and completing the steering action faster. When the vehicle exits a corner, the TVC function will distribute more torque to the front wheels, avoiding "tail swinging" when accelerating out of the corner, and improving the driver's stability in cornering.