Tesla Semi program manager Dan Priestley shared a video showing the electric truck maintaining control on icy surfaces , demonstrating the capabilities of the Vehicle Dynamics Control (VDC) system. This system is designed to manage the stability of a heavy vehicle better than a diesel truck, effectively preventing loss of control.
The VDC system on the Tesla Semi
Priestley explained that the Tesla Semi uses high-resolution sensors and precise multi-motor controls developed in-house to provide torque and stability even on difficult surfaces. The video shows the Semi temporarily losing control on ice, but then regaining it in impressive fashion.
Priestley explained that the truck was loaded during the test with concrete blocks and solid steel bars, which is important because an empty trailer is easier to control than a loaded one. This highlights the effectiveness of the system in real-world conditions.
VDC continuously monitors wheel speed, steering angle and lateral forces, adjusting torque to individual wheels and applying targeted braking to maintain stability. The Semi features an 800 kW three-motor drivetrain producing 1,072 hp, with independent control of the rear motors.
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The advantage of an electric system over a diesel truck lies in its response time. Electric motors can adjust torque output almost instantly, allowing the system to manage power to each wheel in microseconds, which is significantly faster than the hydraulic traction control systems found in conventional trucks. This capability allows the Tesla Semi to precisely control torque distribution moment by moment.
Vehicle rollover, a dangerous situation, often occurs on low-traction surfaces where the drive wheels lose contact with the ground. The Semi’s electric architecture addresses this issue in two ways. First, the battery pack is mounted low on the frame, reducing the center of gravity and the risk of a rollover. Tesla has claimed that the truck would be “impossible to rollover” due to its independent motor control.
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Second, the immediate and granular torque control allows the stability system to correct a skid before it develops into a spin. Unlike a diesel truck, which relies primarily on reactive braking, the Semi can actively steer itself back to stability by applying positive or negative torque to specific wheels.
While this demonstration is produced by Tesla and should be treated with some caution, the underlying physics presents a significant advantage that is difficult for diesel trucks.
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The video comes as Tesla ramps up production of the Semi after years of delays, with the first trucks rolling off the assembly line at the company’s new Nevada factory, which is designed to produce up to 50,000 trucks annually. Tesla has confirmed battery sizes of 822 kWh and 548 kWh for the 500-mile and shorter-range versions, respectively. Communicating safety and stability is critical for fleet buyers, who prioritize uptime and insurance costs, particularly when it comes to rollovers and rollovers.
