Abstract
In this paper, a robust adaptive finite-time (FT) tracking control scheme is proposed for Euler-Lagrange systems (ELSs) subject to nonparametric uncertainties, unknown disturbances and input saturation. In the design procedure, a Gaussian error function is utilized to approximate the input saturation nonlinearity. Following that, by employing the natural property that the upper bound of model parameters uncertainties is linear-in-parameters, the lumped uncertain term caused by uncertain model parameters and external disturbances is formulated by a linear-parametric form with a single parameter. And then, a novel robust adaptive tracking control law is designed to resolve the tracking control problem of uncertain ELSs. The proposed control scheme is featured by FT convergence rate, and robustness against uncertainties and unknown disturbances. Furthermore, the robust adaptive FT tracking control scheme is insensitive to the character of the uncertainties, and is with low computational burden and easy to implement in engineering applications. And its rigorous stability is analyzed with the aid of the Lyapunov stability theory, and its effectiveness is verified by simulation results and comparison.
Highlights
It is well known that Euler-Lagrange systems (ELSs) can describe the motion behaviors of a wide number of physical systems, including robotic manipulators [1], [2], aircrafts [3], surface ships [4], underwater vehicles [5], etc
A robust adaptive FT control law is designed for the uncertain ELSs
In this paper, a novel robust adaptive tracking control scheme has been developed for the ELSs subject to nonparametric uncertainties, unknown disturbances and input saturation
Summary
It is well known that Euler-Lagrange systems (ELSs) can describe the motion behaviors of a wide number of physical systems, including robotic manipulators [1], [2], aircrafts [3], surface ships [4], underwater vehicles [5], etc. The uncertainties are frequently encountered in the operations of ELSs due to unmodeled nonlinearities, unknown parameters and external disturbances, which make the tracking control problem challenging To solve these issues and improve the tracking control performance of ELSs, many control schemes have been presented, such as intelligent control [6]–[8], adaptive control [9]–[11], robust control [12], [13], and sliding mode control (SMC) [14], [15]. Adaptive robust control (ARC) [19], [20] and adaptive SMC [21]–[23] were proposed for the uncertain systems described by ELSs, which were neither computationally intensive nor required the predefined bound These control schemes have extraordinary advantage in theory and applications, all of them are merely ensured by uniform or asymptotic stability, which implies the system trajectory converges to the equilibrium states in infinite time. It is essential for uncertain ELSs to develop a control scheme featured by fast convergence and strong robustness
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