Binary excitation based system identification for precision ballscrew table

Mechanical devices usually come with undesirable nonlinearities such as friction, backlashes and saturation. Under the assumption of linear systems, the commonly seen identification schemes utilize sinusoidal excitation signals for parameter identifications. However, the data for identification are unavoidably distorted by the fore-mentioned nonlinearities and the identification result is not satisfactory. In this paper, a method based on binary excitation signals is proposed. The method does not suffer from the problem of nonlinear distortions in signal shape and is able to determine the bias term for asymmetric frictions such that an accurate model can be derived. An 0.01 /spl mu/m high precision ballscrew table with asymmetric frictions is utilized as a test plant for this approach. To result obtained proves to be very successful.