How Does a Motion Simulator Work? Actuators, DOF and Motion Cues Explained
How does a motion simulator work? In short, the game sends live data about what your car or aircraft is doing, motion software turns that data into small, fast movements, and motors called actuators move your seat or your whole rig to match. Done well, you feel the car load up under braking, the rear step out on a slide and the kerb at the apex before you see them on screen. This guide walks through each part of that chain: the telemetry, the software, the actuators, the degrees of freedom and the motion cueing that makes a few centimetres of travel feel like real g-force.
It is written for anyone weighing up motion for a sim racing or flight sim rig in the UK. Prices quoted are current UK prices from our catalogue, including VAT.
Key takeaways
- The chain: game telemetry, then motion software, then a controller, then actuators that move you.
- It is not a copy of real g-force. A simulator only has a few centimetres of travel, so it gives you the start of each movement and then quietly returns to centre.
- DOF means degrees of freedom: the number of separate directions the system can move you in. Pitch, roll, yaw, heave, surge and sway.
- Actuators do the work. Stroke, speed and load rating matter more than the DOF number on its own.
- Software matters as much as hardware. Good tuning is the difference between motion that informs you and motion that just shakes you.
How does a motion simulator work? The short version
Every modern racing and flight sim outputs telemetry: a constant stream of numbers describing speed, acceleration, rotation, suspension travel and more, many times a second. A motion simulator reads that stream and moves you to match it.
There are four parts to it:
- Telemetry from the game. iRacing, Assetto Corsa Competizione, MSFS, DCS and most other serious titles share it.
- Motion software on your PC. SimHub, SimRacing Studio or the manufacturer's own app takes the raw data, filters it and decides how far and how fast each axis should move.
- A controller. A small box that turns those instructions into commands for each motor.
- Actuators. Electric motors that physically lift, tilt or slide your seat or cockpit.
The whole loop has to be quick. If the movement arrives late, your brain notices that what you feel does not match what you see, and the motion stops feeling helpful.
From game telemetry to movement: what each part does
SimHub and SimRacing Studio are the two most common motion apps. Both support a wide range of racing and flight titles, and both let you save a profile for each game and car.
How do actuators work in sim racing?
An actuator is an electric motor that turns rotation into movement. Most premium systems for home rigs use linear actuators: a servo motor drives a screw, and the screw pushes a rod up and down. Put one under each corner of a cockpit and, by moving them by different amounts, you can tilt it forwards, tilt it sideways or lift the whole thing.
Some platforms use rotary motors with lever arms instead. They work on the same principle: the motor turns, a linkage converts that into lift.
The three actuator specs that matter
- Stroke. How far the actuator can travel. More stroke means room for bigger, longer cues. Qubic's QS-210 has a 60mm stroke and the QS-220 has 100mm, which is a big part of why the 220 feels stronger in heave.
- Speed and response. How quickly it reacts. Fast response is what lets you feel kerbs, gear changes and the first moment of grip loss.
- Load rating. How much mass the actuators can move without running out of force. Add up your driver, cockpit, seat and wheelbase, and leave some headroom under the rating.
Bolt-on actuator systems such as SIMRIG and Qubic sit under an existing aluminium profile cockpit. Full platforms and complete simulators come with their own frame, with the actuators already built in.
Deeper detail: why four actuators can give you three axes
Three axes need at least three actuators, because each actuator only moves in one line. Many 3DOF systems use four, one under each corner. The fourth adds stiffness and spreads the load across the rig, so the cockpit does not twist or rock on its mounts. Qubic's 3DOF Motion Set, for example, uses four actuators for true heave.
Some systems use a pivot instead of a fourth actuator. Qubic's 2.5DOF set pairs its actuators with a central pivot, which gives you pitch and roll plus a simulated heave effect at a lower price than the full four-actuator set.
What is DOF in a motion simulator?
DOF stands for degrees of freedom. It is the number of separate ways the system can move you. There are six in total: three rotations and three straight-line movements.
A 2DOF system usually gives you pitch and roll. 3DOF adds heave, or in some designs yaw for traction loss, as on ProSimu's T1000 3M and P3MP. 6DOF covers all six, which is why full 6DOF simulators such as the ProSimu T1000 7M use seven actuators and start at £23,695.
More DOF is not automatically better. A well-tuned 3DOF system with good stroke will often feel more convincing than a cheap system with more axes and less travel. Our 2DOF vs 3DOF vs 6DOF guide goes through which level suits which driver.
Motion cueing explained: how a few centimetres feels like real g-force
This is the part most people do not expect. A real car pulling 1g under braking is pushing you forward for several seconds. A simulator cannot do that. It would need to keep moving forward for metres.
Instead, motion software uses three tricks, together called motion cueing.
Onset cues
Your body is most sensitive to the start of a movement. So the simulator gives you a sharp, short movement at the moment the force begins: the nose dips as you hit the brakes, the seat drops as the car goes light over a crest. That first jolt does most of the work.
Washout
Straight after the cue, the system eases back towards centre, slowly enough that you do not feel it happen. This is called washout. It frees up stroke for the next cue. Without it, the actuators would sit at the end of their travel and have nothing left to give.
Tilt coordination
For longer forces, the system tilts you. Lean the seat back gently and gravity presses you into it, which your body reads as sustained acceleration. Tilt forward and the harness takes your weight, which feels like a long braking zone. The tilt has to happen slowly, or your inner ear notices the rotation itself.
Specialist tip
Most new owners turn every effect up to the maximum in the first week. Start lower. Set the motion so you can feel braking and kerbs clearly, then add more only where it tells you something useful. If you finish a session feeling tired rather than informed, the effects are too strong or the smoothing is too low.
The main types of motion simulator compared
All of these work on the same principles. What changes is what moves, how much it moves and what it costs.
A seat mover is the simplest way in. Because only the seat moves, the load is mostly just you, and the wheelbase and pedals stay planted. Browse the full range of seat movers if that suits your space and budget. If you already own a solid 8020 rig, a bolt-on system such as the SIMRIG SR2 moves everything, so your hands and feet get the same cues as your body.
Moving the whole rig: pros
- Wheel, pedals and seat all move together
- Most convincing feel for braking and weight transfer
- Works with the cockpit you already own
Moving the whole rig: cons
- More mass to move, so load ratings matter
- Monitors on the rig move with you, floor-standing ones do not
- Higher cost than a seat mover
Where VR fits in a motion simulator
VR and motion work well together. With a headset you move with the cockpit, so there is no mismatch between a moving body and still screens, and a light headset adds almost nothing to the load. There is one catch. A VR headset tracks your head in the room, so when the rig tilts, the game thinks you leaned and your view shifts. Motion compensation fixes this by subtracting the rig's movement from the headset's tracking.
Our guide on what motion compensation is and why your VR sim rig needs it covers how it works and how to set it up.
Our take
Once you understand onset cues and washout, spec sheets make more sense. A motion simulator is not trying to recreate a real car. It is trying to give your body the right signal at the right moment.
That is why we care more about stroke, response and how well the software is tuned than the headline DOF number. A good 3DOF system on a stiff rig, set up properly, beats a bigger number on paper almost every time.
Frequently asked questions
What is a motion simulator?
A motion simulator is a seat, platform or cockpit that moves in time with a racing or flight game. It uses the game's telemetry and electric actuators to give you physical cues such as braking, cornering load, bumps and loss of grip.
Do motion simulators really feel like g-force?
Not exactly. They cannot hold a sustained force, so they use short onset cues, slow washout back to centre and gentle tilt to fool your inner ear. Done well, your brain fills in the rest, and it feels far closer to the real thing than a static rig.
What does DOF mean on a motion platform?
Degrees of freedom: the number of separate directions it can move you. The six are pitch, roll, yaw, heave, surge and sway. Most home systems are 2DOF or 3DOF. Full 6DOF systems move in all six.
What software do I need to run a motion simulator?
Most systems run through SimHub, SimRacing Studio or the manufacturer's own app. The software reads the game's telemetry and sends commands to the actuators. Which one you use depends on the hardware and the games you play.
Do motion simulators work with VR?
Yes, and they suit each other well. You need motion compensation so the headset view does not shift when the rig moves. Most current motion software supports it.
Is a seat mover a real motion simulator?
Yes. It works on the same principles, using actuators and motion cueing, but only the seat moves. Your wheel and pedals stay still. It is a lighter, simpler way into motion, and a good fit for smaller rooms or lighter rigs.
Choosing your first motion simulator
Start with what you already own and what you want to feel. If you have a solid aluminium cockpit, a bolt-on actuator system makes the most of it. If you want the simplest route in, a seat mover is the place to start. If you fly as much as you race, 6DOF opens up more.
You can compare everything in one place in our motion platforms collection. If you are not sure which way to go, email us with your rig, room size and the sims you play, and we will give you a straight answer on what fits.