A 4-poster or four poster automotive test system is specifically designed for the testing of
vehicles
A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...
(cars, trucks).
These test systems consist of 4
hydraulic actuators on top of which the wheels of the vehicle are placed. Movements of the
actuator
An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover".
An actuator requires a control device (controlled by control signal) a ...
s simulate the road surface and forces exerted by the road on the wheels. The movements of the system are tightly controlled by a
digital test controller {{unreferenced, date=November 2008
Digital test controllers are devices (usually computer based) that provide motion control by processing digital signals. Typically a controller has inputs connected to sensors on the device they control, which me ...
. During the research phase of a vehicle a 4-poster system is used to test newly designed
suspension system
Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/ handling and ride q ...
s and their durability. 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. Different kinds of testing are possible: sine test (sweep in frequency); simple wave form on each actuator; open loop test (driven by an external tension signal); a particular testing method called ICS control, which allows to reproduce on a car an actual service environment, starting from those data coming from the outdoor acquisition sessions.
See also
*
7 post shaker
The 7 post shaker is a piece of test equipment used to perform technical analysis on race cars. By applying shaking forces the shaker can emulate banking loads, lateral load transfer, longitudinal weight transfer and ride height sensitive downforc ...
References
Automotive engineering
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