Why does the FREX motion simulation have a fixed steering wheel?
The FREX motion simulator uses a fixed steering wheel for car simulations, since these have traction caused by the grip of the tyres. A good racing driver knows from experience how much lateral G-force is generated by acceleration, braking and taking corners at high speeds; these can push a car to its limits and conditions can change very quickly when these limits are exceeded due to loss of traction.
Luckily, the FREX 6DOF ProSimRig can allow a user to practice driving at the limit of lateral G-force due to the use of a fixed steering wheel, as the relationship between the car body and traction loss due to yaw movements is similar to real-world behaviour.
A motion simulator that moves the whole cockpit is not a good choice for a car simulation, since the lateral G forces expressed by a tilting cockpit induce motion sickness through the movements of roll, sway, pitch and surge. The driver feels only the tilting and vibration, but not a G-force-like effect, and this much clearer with VR Oculus Rift or VIVE. Hence, this is not a good option for professional race car training.
On the other hand, a motion simulator that moves the whole cockpit is a good choice for a flight simulator, since the simple movements of roll, pitch and heave are important; surge, sway and traction loss are less important, since traction is not generated by tyre grip but by the air. In this case, the joystick can be attached to the seat. FREX 6DOF is also ideal for flight simulators.