Abstract
This paper presents an adaptive output feedback control for a manipulator under the presence of the time-varying output constraint and uncertainties. The proposed control is formulated based on a nonlinear extended state observer and a barrier Lyapunov function. The nonlinear extended state observer is developed to estimate the unmeasured states and the lumped uncertainties. Because the observer term in the nonlinear observer includes a linear term and a fractional-order term, its performance is enhanced significantly. Additionally, the barrier Lyapunov function is applied to guarantee the time-varying output constraint, which changes with respect to the desired trajectory in time. The asymptotic stability and output constraint satisfaction are theoretically demonstrated by using the Lyapunov theory. Finally, some simulations are conducted on a 3-DOF manipulator to verify the effectiveness of the proposed control.
Highlights
As one of the greatest potential techniques in the phase of the industrial revolution, robotic has been significantly studied by researchers in universities, institutes, and technology companies in recent years [1]–[3]
(4) In order to verify the superiority of the proposed approach, this algorithm is conducted in a 3-DOF manipulator by simulation with the presence of the time-varying output constraints, unknown frictions, external disturbance, and different working frequencies
In this paper, a novel adaptive output feedback control was proposed for the trajectory tracking control of robot manipulators regardless of the time-varying output constraints, and the external disturbances
Summary
As one of the greatest potential techniques in the phase of the industrial revolution, robotic has been significantly studied by researchers in universities, institutes, and technology companies in recent years [1]–[3]. Based on the above analysis, this paper proposed a novel robust adaptive control for a manipulator with the existence of the time-varying output constraint, and external disturbance. (2) Base on our knowledge, the proposed control is firstly developed for a manipulator regardless of time-varying constraints and uncertainties by using a nonlinear extended state observer to estimate the unknown states and the lumped uncertainties, and the auxiliary term of the barrier Lyapunov functions to isolate the output constraints. (4) In order to verify the superiority of the proposed approach, this algorithm is conducted in a 3-DOF manipulator by simulation with the presence of the time-varying output constraints, unknown frictions, external disturbance, and different working frequencies. PROPOSED CONTROL In this paper, the lumped disturbance, M −1 (x1) (t), of the manipulator dynamics (5) is expanded to a state which is presented by x3 ∈ Rn×1. The control design procedure is implemented based on the Barrier Lyapunov function to handle the time-varying output constraints of the controlled system
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