Self-tuning cooperative control of manipulators with position/orientation uncertainties in the closed-kinematic loop

Abstract

The problem of adaptive control of cooperative manipulators carrying an object in the presence of geometric uncertainties in the closed-kinematic loop is addressed in this paper. The kinematic parameters are estimated in real-time using two cascaded estimators in order to tune a cooperative controller to achieve accurate motion tracking with minimumnorm actuation force. Hence, no force measurement is required to deal with kinematic uncertainties of interconnected robotic system. The stability of the entire real-time estimator/controller system is systematically investigated. The results show that the convergence and stability of the adaptive control process can be ensured if the direction of angular velocity of the object does not remain constant over time. Experimental results demonstrate that even small error in relative position/orentation of two cooperative manipulators can give rise to tracking errors of a conventional inverse dynamic controller while the self-tuning cooperative controller is capable of significantly reducing the tracking errors.

Dexterous robotic manipulation via a dynamic sliding mode force/position control with bounded inputs

“…In the aforementioned works, it is assumed that the manipulated object is mechanically attached to the end‐effectors of the robot manipulators. This assumption simplifies the controller design and stability analysis of the closed‐loop system, since, in many cases, the grasping forces are not controlled [28, 36]. This assumption is unrealistic in some practical applications.…”

Robust Quaternion-based Cooperative Manipulation without Force/Torque Information

“…On the other hand, the representation using unit quaternions, which is employed in this work, constitutes a singularity-free orientation representation, without complicating the control design. Unit quaternions are employed in (Campa et al, 2006;Caccavale et al, 2000Caccavale et al, , 2008Aghili, 2011) for manipulation tasks and in (Erhart and Hirche, 2016) for the analysis of the interaction dynamics in cooperative manipulation.…”

Adaptive force/velocity control for multi-robot cooperative manipulation under uncertain kinematic parameters

“…In [6] an adaptive controller is presented dealing with uncertain kinematic parameters of a single robot. An adaptive control scheme for two cooperating manipulators with geometric uncertainties in the closed kinematic loop is presented in [7]. A least squares approach is used to identify the rigid transformation between the manipulators' end effector frames.…”