An-Chyau Huang

Adaptive sliding control for single-link flexible-joint robot with mismatched uncertainties

An adaptive sliding controller is proposed for a single-link flexible-joint robot with mismatched uncertainties. A backsteppinglike design is used to deal with the mismatched problem and the function approximation technique is employed to transform the uncertainties into finite combinations of orthonormal basis functions. Adaptive laws can thus be derived based on the Lyapunov-like design. Experiment results show that the proposed control strategy gives good tracking performance with all other signals remaining bounded.

Adaptive multiple-surface sliding control for non-autonomous systems with mismatched uncertainties

In this paper, we propose a sliding mode-based controller for a class of single-input single-output nonlinear systems with mismatched uncertainties whose variation bounds are not given. The concept of multiple-surface sliding control is used to cope with the uncertainty mismatch problem, and the function approximation technique is introduced to transform the uncertainties into a finite combination of orthonormal basis functions. An adaptive controller can thus be designed using the Lyapunov approach to achieve output error convergence and boundedness of all signals. Simulation results of a benchmark problem have verified the performance and feasibility of the proposed control strategy.

Adaptive Impedance Control of Robot Manipulators based on Function Approximation Technique

This paper presents an adaptive impedance control scheme for an

Adaptive control of robot manipulators : a unified regressor-free approach

n

Adaptive sliding control of active suspension systems with uncertain hydraulic actuator dynamics

-link constrained rigid robot manipulator without using the regressor. In addition, inversion of the estimated inertia matrix is also avoided and the new design is free from end-point acceleration measurements. The dynamics of the robot manipulator is assumed that all of the matrices in robot model are unavailable. Since these matrices are time-varying and their variation bounds are not given, traditional adaptive or robust designs do not apply. The function approximation technique is used here to represent uncertainties in some finite linear combinations of the orthogonal basis. The dynamics of the output tracking can thus be proved to be a stable first order filter driven by function approximation errors. Using the Lyapunov stability theory, a set of update laws is derived to give closed loop stability with proper tracking performance. A 2 DOF planar robot with environment constraint is used in the computer simulations to test the efficacy of the proposed scheme.

A FAT-based adaptive controller for robot manipulators without regressor matrix: theory and experiments

Dynamic Equations for Robot Manipulators Adaptive Control of Rigid Robots Adaptive Impedance Control of Rigid Robots Adaptive Control of Flexible Joint Robots Adaptive Impedance Control of Flexible Joint Robots

Adaptive impedance controller design for flexible-joint electrically-driven robots without computation of the regressor matrix

An adaptive sliding controller is proposed in this article to control the active suspension systems of a quarter-car model with hydraulic actuator. The highly nonlinear actuator dynamics is assumed to have some time-varying uncertainties with unknown bounds. Owing to its time-variant nature, traditional adaptive designs are not feasible. As the variation bounds are not given, the conventional robust controllers cannot be applied either. In this article, we use the function approximation technique to represent the uncertainties with finite combinations of some basis functions, and the Lyapunov method is employed to find update laws for the coefficients of the approximating series. The actuator force can track the desired force generated from the skyhook dynamics with ultimately bounded performance. If a sufficient number of basis functions are used and the approximation error can be ignored, asymptotic convergence performance can be proved. If the bound of the approximation error is available, asymptotic convergence of the output error still can be obtained with some modifications of the proposed control law. Simulation results show that the controller proposed can give significant improvement of ride comfort when compared with the performance of its passive counterpart.

A regressor-free adaptive controller for robot manipulators without Slotine and Li's modification

In this paper, an adaptive control scheme is proposed for an n-link rigid robot manipulator without using the regressor. The robot is firstly modeled as a set of second-order nonlinear differential equations with the assumption that all of the matrices in that model are unavailable. Since these matrices are time-varying and their variation bounds are not given, traditional adaptive or robust designs do not apply. The function approximation technique (FAT) is used here to represent uncertainties in some finite linear combinations of orthonormal basis. The dynamics of the output tracking can thus be proved to be a stable first order filter driven by function approximation errors. Using the Lyapunov stability theory, a set of update laws is derived to give closed loop stability with proper tracking performance. Experiments are also performed on a 2-D robot to test the efficacy of the proposed scheme.

Design of a regressor-free adaptive impedance controller for flexible-joint electrically-driven robots

To the best of our knowledge, this is the first paper focus on the adaptive impedance control of robot manipulators with consideration of joint flexibility and actuator dynamics. Controller design for this problem is difficult because each joint of the robot has to be described by a fifth-order cascade differential equation. In this paper, a backstepping-like procedure incorporating the model reference adaptive control strategy is employed to construct the impedance controller. The function approximation technique is applied to estimate time-varying uncertainties in the system dynamics. The proposed control law is free from the calculation of the tedious regressor matrix, which is a significant simplification in implementation. Closed-loop stability and boundedness of internal signals are proved by the Lyapunov-like analysis with consideration of the function approximation error. Computer simulation results are presented to demonstrate the usefulness of the proposed scheme.

FAT-based adaptive visual servoing for robots with time varying uncertainties

Robotica / Volume 31 / Issue 07 / October 2013, pp 1051 1058 DOI: 10.1017/S0263574713000301, Published online: 01 May 2013 Link to this article: http://journals.cambridge.org/abstract_S0263574713000301 How to cite this article: Chen-Yu Kai and An-Chyau Huang (2013). A regressor-free adaptive controller for robot manipulators without Slotine and Lis modication. Robotica, 31, pp 1051-1058 doi:10.1017/S0263574713000301 Request Permissions : Click here