Tesla Semi Includes Vehicle Dynamic Controls That Can Prevent Jackknifing [VIDEO]

Tesla Semi Program Lead Dan Priestley shared a video on X showing a Tesla Semi undergoing low-friction winter testing. In the clip, the tractor swings quickly left and then right—a worst-case maneuver for a tractor-trailer. Although the attached trailer fishtails hard from side to side, the Semi itself stays composed.

Let's talk Vehicle Dynamics Control (VDC). With high resolution sensing and precise multi-motor controls developed in-house, the Tesla Semi provides torque and stability even on the trickiest of winter surfaces. pic.twitter.com/xNvCgyQCFc

— Dan Priestley (@danWpriestley) June 25, 2026

Preventing Jackknifing

For conventional diesel rigs, low-friction surfaces are a serious hazard. When a heavy trailer loses traction and begins to swing outward during a turn or a braking event, it applies a rotational force to the tractor’s fifth-wheel coupling.

If the tractor’s mechanical traction control cannot overcome that momentum, the trailer pushes the rear of the truck sideways, producing a jackknife.

Traditional trucks try to mitigate this with pneumatic anti-lock braking systems (ABS) and reactive traction management systems sourced from external suppliers.

The delay for a central controller to detect wheel slip, actuate pneumatic valves, and apply friction brakes is measured in hundreds of milliseconds. In a developing jackknife, that brief latency can be the difference between a recovery and a rollover.

Vehicle Dynamics Control

The Tesla Semi’s stability on ice, even while loaded, comes from a proprietary software suite called Vehicle Dynamics Control (VDC). It uses high-resolution sensing paired with precise, in-house multi-motor control algorithms.

Instead of a single internal combustion engine tied to a mechanical differential, the Tesla Semi employs an independent multi-motor powertrain layout that enables independent wheel torque control.

Because electric motors can change torque output almost instantaneously, the Semi’s VDC core can adjust power delivery to individual drive wheels within microseconds. When high-resolution sensors detect the trailer’s lateral momentum beginning to nudge the tractor off its intended path, VDC issues micro-adjustments to the motors.

It can apply positive torque to one wheel while using regenerative braking on another simultaneously, generating a counter-yaw moment that neutralizes the trailer’s kinetic energy before it can destabilize the tractor.

Vertical Integration at its Finest

Legacy commercial truck manufacturers primarily act as assemblers, sourcing engines, transmissions, and stability control systems from third-party component suppliers. This fragmented approach limits optimization of vehicle control loops because software is often embedded within each component instead of being centralized at the vehicle level.

Because Tesla engineers everything from hardware to software, it achieves tight integration across components—from the VDC software to the vehicle’s physical motors. The system can sample traction in real time, just like it does for its consumer vehicles, and predictively adjust settings to preserve stability.