Adaptive Jacobian Controller Research Articles

Prediction Error Based Adaptive Jacobian Tracking for Free-Floating Space Manipulators

The work presented here investigates task-space trajectory tracking control for free-floating space robots with uncertain kinematics and dynamics. To deal with these two kinds of uncertainties, we propose a prediction error based adaptive Jacobian controller, which includes a modified task-space computed torque controller and two modified least-squares estimators. By defining a new variable that is termed as the estimate of the spacecraft angular acceleration, the proposed controller can work without requiring measurement of the spacecraft angular acceleration. The kinematic and dynamic parameter adaptations are driven by prediction errors. Using input-output stability analysis, we obtain explicit stability results of the closed-loop system and show the asymptotic convergence of the end-effector motion tracking errors of the free-floating manipulator. Furthermore, it is shown that the performance of the proposed controller has a tight relationship with the estimated generalized Jacobians of free-floating manipulators. Simulation results are presented to show the performance of the proposed controller, and in addition some implementation issues of the proposed control algorithm are discussed.

Prediction Error Based Adaptive Jacobian Tracking of Robots With Uncertain Kinematics and Dynamics

In this note, we have proposed a prediction error based adaptive Jacobian controller to solve the problem of concurrent adaptation to both uncertain kinematics and dynamics. This controller is composed of a modified computed torque controller and two cushion floor least-square estimators, and in ideal case of perfect knowledge of the robot parameters it leads to linear and decoupled error dynamics. The kinematic and dynamic parameters adaptations are driven by prediction errors. Using input-output stability analysis, we show that the end-effector motion tracking errors converge asymptotically. We have also derived an alternative adaptive Jacobian controller that does not require the invertibility of the estimated inertia matrix. Simulation results are presented to show the performance of the proposed controllers.

Passivity based adaptive Jacobian tracking for free-floating space manipulators without using spacecraft acceleration

Most research so far on trajectory tracking of free-floating space manipulators has assumed that the kinematics of the space manipulator is exactly known. However, when a space manipulator picks up different tools of unknown lengths or unknown gripping points, its kinematics and dynamics change and are difficult to derive exactly. Thus, in this paper, we have proposed a passivity based adaptive Jacobian controller for free-floating space manipulators. The proposed controller consists of a transposed Jacobian feedback and a dynamic compensation term, and the parameter adaptation laws are derived by Lyapunov-like stability analysis tools. It is shown that the end-effector motion tracking errors converge asymptotically. To avoid using spacecraft acceleration, we define a new reference velocity, which is called spacecraft reference velocity. In addition, we have also conducted passivity interpretation of the proposed controller to obtain some physical insight into its properties. Simulation results are presented to show the performance of the proposed controller.

Adaptive Jacobian Force/Position Tracking Control of Robotic Manipulators in Compliant Contact with an Uncertain Surface

Most research so far on force/position tracking control of robots has assumed that the kinematics and dynamics are exactly known. In this work, we deal with force/position tracking under uncertainties arising from robot kinematics, dynamics, surface stiffness and position with an emphasis on uncertain kinematics. A robot with uncertain kinematics and dynamics in contact with a compliant surface is considered. A new adaptive Jacobian controller has been designed to cope with the uncertain robot kinematics, dynamics, environmental stiffness and position. It is shown that the controller can achieve force and position tracking via Lyapunov stability analysis. Simulation results demonstrate the performance of the controller.

Adaptive Jacobian position/force tracking control of free-flying manipulators

This paper solves the problem of position/force tracking control of a free-flying space manipulator with uncertain kinematics and dynamics. A free-flying manipulator interacting with an uncertain compliant surface is considered. To cope with the uncertainties arising from free-flyer’s kinematics, dynamics and surface stiffness and position, an adaptive Jacobian controller is devised. The convergence of the force and position tracking errors is proved based on Lyapunov stability analysis. Numerical simulation is presented to show the performance of the controller.

An Adaptive Regulator of Robotic Manipulators in the Task Space

This note addresses the problem of position control of robotic manipulators both nonredundant and redundant in the task space. A computationally simple class of task space regulators consisting of a transpose adaptive Jacobian controller plus an adaptive term estimating generalized gravity forces is proposed. The Lyapunov stability theory is used to derive the control scheme. The conditions on controller gains ensuring asymptotic stability are obtained herein in a form of simple inequalities including some information extracted from both robot kinematic and dynamic equations. The performance of the proposed control strategy is illustrated through computer simulations for a direct-drive arm of a SCARA type redundant manipulator with the three revolute kinematic pairs operating in a two-dimensional task space.

Adaptive path-constrained control of a robotic manipulator in a task space

This study addresses the problem of adaptive controlling of both a nonredundant and a redundant robotic manipulator with state-dependent constraints. The task of the robot is to follow a prescribed geometric path given in the task space, by the end-effector. The aforementioned robot task has been solved on the basis of the Lyapunov stability theory, which is used to derive the control scheme. A new adaptive Jacobian controller is proposed in the paper for the path following of the robot, with both uncertain kinematics and dynamics. The numerical simulation results carried out for a planar redundant three-DOF (three degrees of freedom) manipulator whose end-effector follows a prescribed geometric path given in a two-dimensional (2D) task space, illustrate the trajectory performance of the proposed control scheme.