Abstract: A motion platform system comprising a motion platform which is supported above a base by displacement units. Displacement units comprise a drive unit which drives a crank. A connecting arm is connected between the crank and the motion platform, so that translational and tilting movement of the motion platform is achieved by appropriate operation of the drive units. Each connecting arm has a curved profile which enables a full range of movement of the motion platform to be achieved using connecting arms of relatively short length. The connection between the connecting arm and the crank arm can be brought close to, or within, the crank arm. The height of the motion platform above the base, and bearing loads within the drive units, can thus be reduced.