Nonlinear sliding mode control and feasible workspace analysis for a cable suspended robot with input constraints and disturbances

This paper deals with the characterization of the feasible workspace of set-point control for a cable suspended robot. The motivation behind this work is to find admissible set points for the system under disturbances as well as input constraints. The main ideas are: (i) designing a sliding mode controller as a stabilizing controller for the given uncertain system, (ii) finding the range of system states in terms of set points by analyzing the reaching condition and sliding mode, and (iii) substituting states in inequalities of the input with either their upper values or lower values so that constraints are satisfied. This method results in 6 inequalities in terms of set point which can be drawn graphically in the 3-dimensional space.