On February 28, 2024, Bosch held a winter test experience event with the theme of "Creating and Sharing Intelligent Control, Enlightening the Future". This time, we focused on experiencing the five chassis control technology functions represented by VMM cross-actuator fusion technology.
VMM stands for Vehicle Motion Management, which integrates a variety of chassis control systems including braking system, drive system, front-wheel steering, rear-wheel steering, and suspension system, and is developed by Bosch's Vehicle Motion Control Systems division.
Bosch Vehicle Motion Control Systems was formed in January 2024 by the merger of Bosch Chassis Control Systems and Bosch Commercial Vehicle Steering. The business scope includes commercial vehicle steering, braking systems, vehicle motion control system solutions, driving and passenger safety systems, vehicle dynamic sensors, and passenger car steering (under Bosch Huayu Steering Systems in China*** Zhang Ying is the president of Bosch Vehicle Motion Control Systems China.
Headquartered in Suzhou, Jiangsu Province, Bosch Vehicle Motion Control System China has winter automotive technical test centers in Hulunbuir, Inner Mongolia, and all-season automotive technical test centers in Donghai, Jiangsu Province, as well as production bases in Chengdu, Sichuan, Nanjing, Jiangsu Province, and Jinan, Shandong Province.
Founded in 2007, the site of this winter test is Bosch (Hulunbuir) Automotive Technology Center, with a total area of 1.86 million square meters, including 540,000 square meters of land test area and 1.32 million square meters of lake test area. Yakeshi is in winter for up to 5 months throughout the year, so the winter test time can last from the beginning of December to the middle of March of the next year, which can meet the friction coefficient requirements under different conditions, as well as the field test of various working conditions, and is one of the professional venues for the winter test of domestic automotive technology.
Chassis Control Technology Base - VMM Cross Actuator Fusion Bosch released the VDC2 back in 20220 vehicle dynamic control, this VMM cross-actuator fusion scheme is its technical upgrade scheme. In addition to the system's fusion control, the front-wheel steering in this prototype is equipped with Bosch's latest steer-by-wire system, and the hardware performance has also been improved.
Thanks to the dynamic fusion control of multiple systems, the superimposed steer-by-wire is correspondingly faster, which makes the vehicle more stable under extreme working conditions, including slippery roads and roads with different adhesion on the left and right sides. In the face of sudden working conditions and emergency avoidance, the body posture is more stable to prevent sliding or even rollover. At the same time, steer-by-wire decouples the wheels from the steering wheel, and under extreme working conditions, the high-frequency swing of the wheels is completely eliminated by the system, and will not be directly fed back to the steering wheel, reducing the driver's tension in the face of extreme working conditions.
In addition to the functional performance, it is worth mentioning the speed of development of the Bosch team. Bosch Zhang Ying revealed that the prototype equipped with VMM took only two months to assemble and was immediately put into winter testing. The speed of development also reflects Bosch's deep accumulation of chassis control technology.
Based on the VMM technology framework, Bosch realizes the development of a variety of functions through the integration of different controls. The OMP, ITAS, TV, and IEC launched this time are all typical functional applications under the framework of VMM technology.
The full name of OMP is ONE Move Parking System, in fact, it can be seen from the English name that its purpose is to make the vehicle more silky to achieve automatic parking. In the existing automatic parking process, when the parking system is given the parking path, the vehicle inevitably begins to rotate the direction in situ, and the forward and backward pitch of the vehicle attitude is also more serious when parking. The OMP is the same as the existing parking execution path, and the parking system starts to park after the parking path is given. The difference is that after receiving the parking path, the OMP system does not first reverse the direction, but first drives the vehicle to drive, and the steering system receives the driving torque information and then adjusts the direction, which conforms to the logical process of the driver's manual parking, and avoids the noise and tire wear caused by hitting the direction on the spot. When the vehicle is about to stop, combined with the braking system's own control algorithm, the vehicle is prevented from nodding. At present, the algorithm can be directly run in the IPB controller, and only needs to be linked with the signal of the electric drive system and steering system, without changing the hardware structure.
ITAS stands for Intelligent Turn Assistance System, which is a turning radius that is as close to the U-turn as possible. The Leopard 5 is equipped with this function, and its turning radius can be as small as 34 meters, far lower than other similar competing models. The principle is that when the function is turned on, the front and rear drive motors rotate in the opposite direction, that is, the front wheel motor is driven forward, and the rear wheel motor is driven backward. At the same time, the braking system locks the vehicle from turning the unilateral wheel of the rear wheel in the opposite direction, that is, locks the right rear wheel when turning left, and locks the left rear wheel when turning right. In this way, the effect of making a U-turn on the spot is achieved. The hardware conditions to realize this function are mainly in the electric drive system, and the minimum requirement is dual motor and four-wheel drive.
IEC stands for Intelligent Escape Control, which uses brake control to get the vehicle out of trouble, close to the performance of mechanical differential lock. Different from the electronic differential lock, IEC combines traction control system and suspension control system at the same time, which can identify the complex working conditions of the road surface in time, reduce the maximum wheel speed difference by 60%, and combine the fusion control of the suspension system to reduce the vertical disturbance of the body by 50%, and realize the vehicle off-road road conditions more smoothly.
The full name of TV is torque vectoring, that is, through the distribution control of the torque of each wheel, while optimizing the road adhesion utilization rate, combined with the motor torque control to achieve effective control of the attitude of the whole vehicle, while reducing braking intervention, to achieve good dynamic control of the vehicle on the high adhesion road or low adhesion road surface.
Zhang Ying mentioned on the spot that in terms of strategy, Bosch adheres to the customer-oriented needs of OEMs and provides integrated system solutions. However, in terms of product development, Bosch pays more attention to the end-user experience and focuses on creating a new driving experience for the end consumer.
According to daily use, car use scenarios can be divided into four categories. They are urban traffic, high-end official business, hardcore off-road, and extreme sports.
In urban traffic, more attention is paid to the economy and comfort of daily driving, and Bosch OMP and EDTC functions are developed for this scenario.
High-end business more pursuit of the ultimate comfort, Bosch CST20 is developed for this scenario, the braking impact is reduced by 50%, and the brake does not nod. At the same time, it is also necessary to have strong handling in this scenario to cope with sudden unexpected working conditions, and because more users in this scene choose large vehicles similar to MPVs, it is more difficult to control dynamically. The Bosch VMM cross-domain fusion solution solves the needs of large models in this scenario, while taking into account comfort and dynamic control.
Hardcore off-road is more important for the ability to pass through all-terrain conditions, Bosch ITAS can meet the requirements for the turning radius, and IEC can meet the requirements for the vehicle to get out of trouble.
Extreme sports need to push the boundaries of safety in extreme working conditions as much as possible, and pursue higher speed and passion. Bosch TV and IDCS (Intelligent Drift Function) were developed for this scenario. TV can reduce the intervention of braking in corners, and IDCS is designed to improve the dynamic control performance of the vehicle when drifting, and reduce the difficulty of vehicle drifting.
In the future, with the emergence of more user needs, the continuous expansion of functions can be further realized based on the VMM technology framework. It is worth mentioning that all of the above functions can be developed and mass-produced by the Bosch China team.
Electrification and intelligence are considered to be the two important directions of future automobiles, and as they continue to be accepted by consumers, new car needs will follow, which is typically manifested in personalization and scenario-based. VMM's cross-actuator fusion technology provides technical possibilities for the development of multiple functions to meet the diverse needs of consumers. At the same time, the fully integrated VMM technology solution can maximize the dynamic control of the vehicle, so that consumers can safely enjoy the control experience brought by the high-power drive of electric vehicles.