Intermittent Control: Stability and performance analysis of intermittent threshold functions for unstable systems

Intermittent control is widely used in various robotic applications and a variety of literature is available on the same. An intermittent control strategy monitors variables of interest continuously and takes corrective action intermittently when variables exceed threshold criteria. The threshold functions evaluated are mostly complex, though simple functions using logical operations on state variables are not much explored. In this paper, we study performance of intermittent control with different threshold functions on state variables in 1-DOF and 2 DOF robotic systems. The performance analysis is conducted using the controller efforts measurement and the stability is evaluated with the phase-plane analysis. We find that in the SIP system, functions with both the logic operations are stable in state-space and the function with the OR operator is more performance efficient than the AND operator. Similar results are found in the RDIP system with the bounds on the states being very low to reduce the controller efforts.