A fast converging adaptive control scheme for suppression of broadband disturbances on a multi-variable vibration isolation setup

For research and development, a single reference input multiple actuator input multiple error sensor output vibration isolation setup is realized. The objective of the setup is to investigate if the flexible receiver structure can be isolated from the rigid source structure by six piezo-electric actuators (serving as a hybrid vibration isolation mounts), such that disturbances stemming from the source structure are reduced at the receiver structure. Vibration isolation is established by minimizing signals from six acceleration sensor outputs and by steering the piezo-electric actuator inputs. The first contribution of this paper is that by making use of an adaptive multi-variable feedforward controller which is updated on the basis of a computationally efficient filtered error least mean square algorithm, broadband vibration isolation control is achieved with an average reduction of up to 9.4 dB in the error sensor outputs (between 0-1 kHz). The second contribution is that the slow convergence problem of the adaptive controller is solved by incorporating the multi-variable state space based inverse outer factor model in the control scheme. The latter is obtained from an inner/outer factorization of the state space model of the transfer path between the actuator inputs and error sensor outputs.