Tracking Control for a Robotic Manipulator under Constraint Violation during Operation and Unknown Initial Conditions

In this paper, we proposed an adaptive control scheme for a robotic manipulator with continuous repetitive deferred and constant (CRDC) output performance constraints. A new shifting function for performance errors is introduced and entrapped into barrier Lyapunov function (BLF) to address the negative aspects of barrier functions. By adopting this error shifting function into control synthesis, a tracking control approach considering uncertain initial conditions and external perturbations is first developed for the robotic manipulator to guarantee CRDC output constraints. In the other existing literatures, the system states must satisfy the prescribed constraints initially, and cannot violate the constraints during system operation. However, the novel scheme is able to address the aforementioned situation, and the prescribed constraints can be violated both procedurally and initially. Thus, the proposed method is more applicable. The effectiveness of this novel control scheme is demonstrated in simulation.