Model-based MIMO state-space control of a car vibration test rig with four electromagnetic actuators for the tracking of road measurements

A car vibration test rig with four electromagnetic actuators is presented. It excites a vehicle body for the simulation of road drives in squeak and rattle analyses. This novel application distinguishes itself by a very compact construction, few demands on peripherals, and high energetic efficiency. Its drawbacks are inherent actuator instability and distinct shaker-to-shaker couplings. These are considered in the design of a state-space system model of order 22. A multiple-input-multiple-output controller based on this model provides silent stabilization and high bandwidth. The vehicle under test remains sensorless during normal plant operation, as its states are estimated by a reduced observer. It is equipped with four or eight accelerometers only for the nonrecurring process of stimulus file generation. Road-measured reference trajectories are hereby replicated with iterative learning control methods. Experimental results prove that the plant is capable of a realistic excitation of the vehicle.