A motion platform cannot hold you under real, sustained G-force; its actuators only travel a few inches. Instead it cues the sensation. A short, sharp movement signals the start of braking or cornering, the seat then drifts back to center too slowly to notice, and the seat tilts so gravity presses you into the seatback or bolster the way acceleration would. Your inner ear cannot tell that tilt from real acceleration, and your eyes fill in the rest.
What your body actually senses
The otolith organs in the inner ear sense both linear acceleration and head tilt relative to gravity, and they cannot tell the two apart. NASA's research on simulator motion cueing describes this as the basis of "tilt coordination": tilting the platform slowly, below the rate you can perceive, adds a sustained push to the brief cues from other movements (NASA/CR-2005-213747).
The three tricks motion platforms use
- Onset cues. When you hit the brakes, the platform moves sharply in the direction that matches the change in acceleration.
- Washout. Because travel is limited, the platform returns toward neutral after the onset cue, below your perceptual threshold, so it has room for the next event. NASA describes washout filters as removing long-duration, low-frequency motion (NASA).
- Tilt coordination. For forces that last, such as a long corner, the seat tilts so part of gravity acts sideways or backward on your body (NASA).
Mapping car forces to seat movement
Motion is described in six degrees of freedom: three movements (surge forward and back, sway side to side, heave up and down) and three rotations (pitch, roll and yaw) (background). Sim-racing platforms rarely use all six. SIGMA Integrale explains how its software converts surge (braking and acceleration) into responsive pitch, converts sway (cornering) into roll, and uses a separate heave layer for low-frequency vertical motion up to 10 Hz, such as suspension settling after a bump (SIGMA Integrale).
| What the car does | What you feel in a real car | How the platform cues it |
|---|---|---|
| Hard braking | Pushed forward into the belts | Seat pitches nose-down |
| Accelerating | Pressed into the seatback | Seat pitches nose-up |
| Cornering | Pushed toward the outside of the turn | Seat rolls toward the outside |
| Bumps and curbs | Up-and-down jolts | Heave and vibration |
SIGMA also adds high-frequency vibration layers for engine and road texture, up to 85 Hz on the DK2 and 94 Hz on the DK2+/DK6+ (SIGMA Integrale).
Why the visuals matter
Motion works with your eyes, not instead of them. When visual and vestibular signals disagree, people are more likely to feel simulator sickness (CHOP). Well-tuned motion and low input lag help keep the two in step.
2DOF vs 3DOF
A two-axis system concentrates on pitch and roll, the rotations that tilt coordination depends on. A three-axis system can add heave for bumps and vertical load. Our motion simulator DOF comparison explains the options, and hydraulic vs electric motion platforms covers the actuators.
What SimsForHire uses
Our 10 full-motion rigs use SIGMA Integrale 2DOF/3DOF motion platforms with electric actuators, and every rig we rent is full-motion. We deliver, set up, staff and tear down at corporate events, private parties, trade shows and brand activations. Full-motion rigs are $2,750 per day, plus tax and insurance; see pricing or call (754) 228-5654.