Prescribed Performance Control of Uncertain MIMO Nonlinear Systems With Coupled and Constrained Inputs

This letter addresses prescribed performance control (PPC) for uncertain multi-input multi-output (MIMO) nonlinear systems subject to saturated and coupled inputs. The proposed controller requires no model parameter knowledge and is of low implementation complexity, i.e., no regressors, observers, or approximation structures are utilized. We derive explicit feasibility conditions linking saturation levels to performance envelopes, system parameters, gains as well as disturbances, and effectively extend the low-complexity results on prescribed performance control with input saturation to the case of input coupling. Boundedness of all closed-loop signals and prescribed-performance tracking are established. A planar two-link manipulator simulation validates the approach.