Ship motion simulator
The CSIR supports naval forces by developing optronics for improved maritime surveillance. To accurately test these systems during the development phase, a simulator, which emulates a ship’s movement at sea, was developed.
The ship motion simulator is a modified version of the three-degrees-of-freedom Stewart platform. It operates on a roll-and-pitch axis at different frequencies and amplitudes using a combination of pneumatic actuators and position feedback into a custom control system. In this way, optronics experts could be sure that the camera system will be effective despite the challenges of shifting horizons, changing clouds and water swells obscuring objects.
The CSIR has made the simulator available to the University of Pretoria’s Department of Mechanical Engineering to support postgraduate research on mathematical modelling and control systems. The University of Pretoria devised the control system for the ship motion simulator.
Using this same methodology, the team also studies motion platforms to support systems on mobile land-based patrol or response vehicles.
The system is based on a modified version of the three-degrees-of-freedom Stewart platform. This platform is a type of parallel robot that has six prismatic actuators, commonly hydraulic jacks or electric actuators, attached in pairs to three positions on the platform's baseplate, crossing over to three mounting points on a top plate. Devices placed on the top plate can be moved in the six degrees of freedom in which it is possible for a freely-suspended body to move. These are the three linear movements (lateral, longitudinal and vertical) and the three rotations (pitch, roll and yaw).