New Robust Tracking Control for Safe Constrained Robots under Unknown Impedance Environment (original) (raw)
Robust Tracking Control for Constrained Robots
Procedia Engineering, 2012
In this paper, a novel robust tracking control law is proposed for constrained robots under unknown stiffness environment. The stability and the robustness of the controller are proved using a Lyapunov-based approach where the relationship between the error dynamics of the robotic system and its energy is investigated. Finally, a 3DOF constrained robotic arm is used to prove the stability, the robustness and the safety of the proposed approach.
Robust Impedance Control-based Lyapunov-Hamiltonian Approach for Constrained Robots
International Journal of Advanced Robotic Systems, 2015
A new design of a robust impedance controller for constrained robotic manipulators is presented. The main objective is to stabilize asymptotically, in the task space, the robotic manipulator's end effectors into a desired position, via a desired contact force under model uncertainties and measurement noise. In this work, the proposed approach is enough straightforward for application without force and position control separation. Robust asymptotic stability in the approach is proved using a Hamiltonian-Lyapunov approach. Besides this, a state/parameter observer and an acceleration estimator are proposed to handle the problems of force estimation, disturbance rejection and acceleration measurement. To ensure high performance, a Particle Swarm Optimization (PSO) algorithm is used finally as an efficient and fast method for the offline fine-tuning of the controller's parameters. In designing the PSO method, the Mean of Root Squared Error (MRSE) is considered as a cost function in the Cartesian space. Finally, the example of the ABB-IRB 140 industrial robot with 6DOFs is used to validate the performances of the proposed approach.
A Lyapunov-based design tool of impedance controllers for robot manipulators
Kybernetika, 2012
This paper presents a design tool of impedance controllers for robot manipulators, based on the formulation of Lyapunov functions. The proposed control approach addresses two challenges: the regulation of the interaction forces, ensured by the impedance error converging to zero, while preserving a suitable path tracking despite constraints imposed by the environment. The asymptotic stability of an equilibrium point of the system, composed by full nonlinear robot dynamics and the impedance control, is demonstrated according to Lyapunov's direct method. The system's performance was tested through the real-time experimental implementation of an interaction task involving a two degree-of-freedom, direct-drive robot.
Robust impedance control of robotic manipulators
2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004
A task space robust trajectory tracking control is developed for robotic manipulators. A second order linear model, which defines the desired impedance for the robot, is used to generate the reference position, velocity and acceleration trajectories under the influence of an external force. The control objective is to make the robotic manipulator's end effector to track the reference trajectories in the task space. A sliding mode based robust control is used to deal with system uncertainties and unmodeled dynamics. Thus, a sliding manifold is defined by a linear combination of the tracking errors of the system in the task space built from the difference between the real and the desired position, velocity and acceleration trajectories. Moreover, the ideal relay has been substituted by a relay with a dead-zone in order to fit in with the actual way in which a real computational device implements the sign function being typical in sliding mode control. Furthermore, a higher level supervision algorithm is proposed in order to reduce the amplitude of the high frequency components of the output associated to a overestimation of the system uncertainties bounds. Then, the robust control law is applied to the case of a robot with parametric uncertainties and unmodeled dynamics. The closed-loop system is proved to be stable while the control objective fulfilled is in practice. Finally, a simulation example which shows the usefulness of the proposed scheme is presented.
International Journal of Applied Mathematics and Computer Science
The main impedance control schemes in the task space require accurate knowledge of the kinematics and dynamics of the robotic system to be controlled. In order to eliminate this dependence and preserve the structure of this kind of algorithms, this paper presents an adaptive impedance control approach to robot manipulators with kinematic and dynamic parametric uncertainty. The proposed scheme is an inverse dynamics control law that leads to the closed-loop system having a PD structure whose equilibrium point converges asymptotically to zero according to the formal stability analysis in the Lyapunov sense. In addition, the general structure of the scheme is composed of continuous functions and includes the modeling of most of the physical phenomena present in the dynamics of the robotic system. The main feature of this control scheme is that it allows precise path tracking in both free and constrained spaces (if the robot is in contact with the environment). The proper behavior of th...
A Dynamic-compensation Approach to Impedance Control of Robot Manipulators
Journal of Intelligent and Robotic Systems, 2011
This paper presents an impedance–control strategy with dynamic compensation for interaction control of robot manipulators. The proposed impedance controller has been developed considering that the equilibrium point of the closed-loop system, composed by the combination of the controller and the full nonlinear robot dynamics is, locally, asymptotically stable in agreement with Lyapunov’s direct method. The performance of the proposed controller is verified through simulation and experimental results obtained from the implementation of an interaction task involving a two degree-of-freedom, direct-drive robot.
Force-Impedance Control: a New Control Strategy of Robotic Manipulators
Recent Advances in Mechatronics, 1999
Abstract. A novel control strategy of robotic manipulators is presented in this paper: the force-impedance controller. This controller enables two kinds of behaviour: force limited impedance control and position limited force control. The type of behaviour only depends ...
Adaptive trajectory/force control scheme for constrained robot manipulators
International Journal of Adaptive Control and Signal Processing, 1993
An adaptive control scheme for the trajectory/force tracking of robot manipulators is presented. Asymptotic stability of state variables and convergence of constraint forces to any prespecified set are proven. The design procedure avoids the restrictive solvability condition of the constraint equation in the whole space of robot co‐ordinates. A fairly accurate bound of the tracking error is derived by means of a Lyapunov analysis.
Robust adaptive motion/force tracking control design for uncertain constrained robot manipulators☆
Automatica, 2004
In the presence of uncertain constraint and robot model, an adaptive controller with robust motion/force tracking performance for constrained robot manipulators is proposed. First, robust motion and force tracking is considered, where a performance criterion containing disturbance and estimated parameter attenuations is presented. Then the proposed controller utilizes an adaptive scheme and an auxiliary control law to deal with the uncertain environmental constraint, disturbances, and robotic modeling uncertainties. After solving a simple linear matrix inequality for gain conditions, the effect from disturbance and estimated parameter errors to motion/force errors is attenuated to an arbitrary prescribed level. Moreover, if the disturbance and estimated parameter errors are square-integrable, then an asymptotic motion tracking is achieved while the force error is as small as the inversion of control gain. Finally, numerical simulation results for a constrained planar robot illustrate the expected performance.
Robust Impedance Control of Manipulators Carrying a Heavy Payload
Journal of Dynamic Systems Measurement and Control, 2010
A heavy payload attached to the wrist force/moment ͑F / M͒ sensor of a manipulator can cause the conventional impedance controller to fail in establishing the desired impedance due to the noncontact components of the force measurement, i.e., the inertial and gravitational forces of the payload. This paper proposes an impedance control scheme for such a manipulator to accurately shape its force-response without needing any acceleration measurement. Therefore, no wrist accelerometer or a dynamic estimator for compensating the inertial load forces is required. The impedance controller is further developed using an inner/outer loop feedback approach that not only overcomes the robot dynamics uncertainty, but also allows the specification of the target impedance model in a general form, e.g., a nonlinear model. The stability and convergence of the impedance controller are analytically investigated, and the results show that the control input remains bounded provided that the desired inertia is selected to be different from the payload inertia. Experimental results demonstrate that the proposed impedance controller is able to accurately shape the impedance of a manipulator carrying a relatively heavy load according to the desired impedance model.