• Response: a system that has perceptible lag, either on the hardware (changing position) side or software (processing) side, creates a disconnect between user input and feedback. This quickly results in the users feeling like the system is only tossing them around rather than actually simulating what the vehicle is doing.

• Range: with a limited displacement, the system quickly runs out of motion range. Even with the best response time, if the motion system stops moving, it is not simulating motion anymore which quickly reduces realism and immersion because the vehicle could still be moving on the screen. Aside from specific custom applications, every motion system is going to run out of range at some point so pairing the right system with the application is critical.

• Control: translating telemetry from the sim software into motion is critical especially in terms of “fidelity” so you can differentiate between subtle motions and large displacements and everything in between. This is very pronounced in driving where the system needs to simulate road texture, rumble strips or kerbs, engine vibrations, etc. differently from large motions like dropping a wheel, elevation changes, banked corners, weight transfer, or suspension movement in general, etc.

• Surge is horizontal movement forwards and backwards. Surge motion simulates the true feeling of acceleration and braking in the seat of the pants like a real vehicle; “pushing” the driver or pilot in acceleration and “pulling” the driver or pilot in braking/deceleration.

• Sway is horizontal movement left and right. Sway motion simulates the true feeling of lateral acceleration (i.e. when turning) due to centrifugal forces (i.e. the driver or pilot being “pushed” to the outside of the turn); a very common measurement of a car’s grip (i.e. lat-g or lateral g) is a result of this centrifugal force acting on the driver and the car.
  

• Heave is vertical movement up and down. Heave motion simulates the true feeling of elevation changes (in flight or driving up/down inclines), hitting bumps, suspension compression and rebound, rumble strips/kerbs on track, and more.

• Pitch is rotational movement (tilting) forwards and backwards. Pitch simulates aircraft movement when changing elevation (i.e. altitude change) and car movement as a result of weight transfer due to acceleration and braking (i.e. brake dive), bumps, dips, going up inclines, and more. 

• Roll is rotational movement (tilting) left and right. Roll simulates aircraft movement when changing direction and car movement as a result of weight transfer due to turning as well as driving around banked corners (i.e. such as Carousel at the Nürbugring) and uneven bumps, dips, and road features.

• Yaw is rotational movement horizontally. Yaw simulates the rotation of an aircraft or vehicle while changing direction and in vehicles, it also simulates loss of grip such as drifting. It’s important to remember that the vast majority of motion simulators capable of yaw can only simulate a fixed yaw axis. The simulator always rotates the same way no matter what the vehicle or aircraft is doing (i.e. no distinction between oversteer and understeer or mid-engine vs front engine vs rear-engine in a car for instance) 

Often times, you will see marketing terms such as “full motion” which don’t actually simulate all 6 DOF. Instead, they simulate only 2 DOF, 3 DOF, or 4 DOF with only “motion compensation” in the missing axes. We make it a priority to educate our customers what’s behind the marketing lingo so they know exactly what they are getting.