Decoupled decentral control of electromagnetic actuators for car vibration excitation

Electromagnetic actuators have proven useful for the vibration excitation of components. Their inherent instability can be compensated by adequate feedback control. For realistic car excitation, at least two actuators are necessary that are clamped to the car body. Their interaction is governed by the dynamic behaviour of the jacking points and is especially high at a system resonance frequency. The resulting intense couplings cause problems when two independent decentral SISO (single input single output) controllers are used. Weakening the SISO controller gains to diminish coupling effects is impossible as the control parameters have to be high enough to stabilize each actuator. A solution to these problems is to decouple the two SISO controllers statically by diagonalizing the system at the resonance frequency. Two decoupling approaches are applied, both of them based on system identifications: SVD (singular value decomposition) and DTM (dyadic transfer function matrices). Both strategies are adapted to the specific state-space SISO controllers and decouple only the states that are physically coupled in a direct manner. Since interaction is strong merely at the system´s resonance frequency, static decoupling works well and reduces permanent disturbances significantly while enabling increased control parameters at the same time. Due to a reference tracking configuration of the decoupled state-space controllers named tracking error estimation, the achieved bandwidth matches the desired 100 hertz.