The design of a precision digital integrator for use in an active vibration control system

Hodges, T., Nelson, P. A. and Elliott, S. J. (1990) The design of a precision digital integrator for use in an active vibration control system. Mechanical Systems and Signal Processing, 4 (4), 345-353. (doi:10.1016/0888-3270(90)90012-A).

Abstract

Active feedback control techniques may be used to modify the dynamic response of a vibrating structure. This paper describes the design and implementation of a digital integrator which is used in a control system to modify the structural frequency response of a cantilever beam. The beam, which is driven by band-limited stationary excitation, may be modeled as a second order system with the modal series truncated and approximated by a residual stiffness term. The design of a high precision digital integrator is found to be necessary. Two integrator designs are implemented, and the integrator used for experimental work is designed to compensate for the half-sample delay introduced by the sample-hold circuitry; this design provides integration which is accurate to within 1° over a frequency range of 1·5 Hz to the Nyquist frequency. The controller is used to provide velocity and displacement signals from an input acceleration signal which allows alteration of the modal parameters of the first mode of the beam. The controller is implemented using a Texas Instruments TMS 32020 Digital Signal Processor operating at sample rates of up to 44 kHz, and experimental results are presented which demonstrate the alteration of the natural frequency and damping ratio of the fundamental mode of the cantilever.

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Contributors

Author: P. A. Nelson

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