On positive output controllability and cable driven parallel manipulators

This paper introduces a new concept: the positive output controllability for a multi-link cable driven parallel manipulator (CDPM). This class of mechanism is characterised by the use of cable actuation which is constrained to be non-negative at all times. For simplicity, a linear-time-invariant system (LTI) is considered, which corresponds to the local behavior of the CDPMs around an particular equilibrium. A necessary and sufficient condition is provided to ensure that a LTI system is positive output controllable. The obtained results are verified by using a simulation example of a 2-link CDPM.