47 research outputs found
Adaptive dynamic surface control based on fuzzy disturbance observer for drive system with elastic coupling
Robust Integral of Sign of Error and Neural Network Control for Servo System with Continuous Friction
Robust Integral of Sign of Error and Neural Network Control for Servo System with Continuous Friction
Robust tracking and vibration suppression for nonlinear two-inertia system via modified dynamic surface control with error constraint
Robust tracking and vibration suppression for nonlinear two-inertia system via modified dynamic surface control with error constraint
Unknown dynamics estimator-based output-feedback control for nonlinear pure-feedback systems
Most existing adaptive control designs for nonlinear pure-feedback systems have been derived based on backstepping or dynamic surface control (DSC) methods, requiring full system states to be measurable. The neural networks (NNs) or fuzzy logic systems (FLSs) used to accommodate uncertainties also impose demanding computational cost and sluggish convergence. To address these issues, this paper proposes a new output-feedback control for uncertain pure-feedback systems without using backstepping and function approximator. A coordinate transform is first used to represent the pure-feedback system in a canonical form to evade using the backstepping or DSC scheme. Then the Levant's differentiator is used to reconstruct the unknown states of the derived canonical system. Finally, a new unknown system dynamics estimator with only one tuning parameter is developed to compensate for the lumped unknown dynamics in the feedback control. This leads to an alternative, simple approximation-free control method for pure-feedback systems, where only the system output needs to be measured. The stability of the closed-loop control system, including the unknown dynamics estimator and the feedback control is proved. Comparative simulations and experiments based on a PMSM test-rig are carried out to test and validate the effectiveness of the proposed method