Robust PI controller design for a constant turning force system

Abstract

While a cutting tool is cutting a workpiece at various cutting depths, it goes through a nonlinear time-varying process. The stability of the turning force control system in this process can not be assured by the classical control theory. In this paper, the force control system is considered to be a linear one with a nonlinear time-varying perturbation. Using the functional analysis and Bellman-Gronwall inequality, a simple robust stability criterion is derived from the state space approach. For the simplicity of implementation, the PI controller is employed to treat this stabilization problems, whose design procedure for specifying the control parameters is also proposed according to the robust stability criterion. The illustrative results of the computer simulation and practical experiments show that the control parameters, obtained by the design procedure, show better output responses than other control parameters in gain space.