Real-Time Implementation Issues in Nonlinear Model Inversion

Abstract

A real-time control problem associated with a flexible testbed fixture is considered. The regulated variable is the deflection at the tip of a flexible beam attached to an inertia wheel base which is subject to a disturbance torque. The control torque affects the base wheel through a coupling which has both compliance and variable backlash. The performance specifications include disturbance attenuation and rapid slewing at the tip. The designs are based on an analytically derived continuous-time model which is tuned in accordance with the measured data. The model consists of an interconnection of a linear time-invariant part and piecewise-linear algebraic nonlinearities modeling friction and backlash. The candidate designs must be based on available measurements only; more-over, the final discrete-time control law must be executable with the real-time controller hardware limitations at hand.