} 4-poster or four poster automotive test system is specifically designed for the testing of vehicles (cars, trucks). These test systems consist of 4 Electro-Magnetic Actuators on top of which the wheels(tires) of the vehicle are placed. Movements of the actuator simulate the road surface and forces exerted by the road on the wheels(tires). The movements of the system are tightly controlled by a digital test controller with road load data etc. During the research phase of a vehicle a 4-poster system is used to test newly designed suspension systems and their durability and noise/vibration from structure born. In production 4-poster systems are usually used to test every vehicle at the end of the production line on squeak and rattle, which is a check to make sure the vehicle doesn't have any loose parts.