Cooperation of robotic manipulators using non‐model‐based multiple impedance control

PurposeThe aim of this paper is to present the non‐model‐based multiple impedance control (NMIC) law for object manipulation tasks, which can be implemented with reasonable limited on‐line computations.Design/methodology/approachThe multiple impedance control (MIC) is a model‐based algorithm that enforces a designated impedance on all cooperating manipulators, and the manipulated object itself. In this paper, the MIC law is modified to be implemented without using system dynamics. Therefore, this modified MIC law is a quick and more realistic algorithm for implementation in cooperating robotic systems, and so is called NMIC. Developing the NMIC law, error analysis shows that under the NMIC law all participating manipulators, and the manipulated object exhibit the same designated impedance behavior. Next, the proposed NMIC law is applied on an object manipulation task with three cooperating PUMA 560 manipulators while two of them are equipped with a remote compliant centre.FindingsDeveloping the NMIC law, error analysis shows that under the NMIC law all participating manipulators, and the manipulated object exhibit the same designated impedance behavior. The obtained results show good tracking performance even in the presence of impacts due to contact with an obstacle, and also system flexibility.Practical implicationsThe obtained results show good tracking performance even in the presence of impacts due to contact with an obstacle, and also system flexibility. These results reveal the merits of NMIC law as a non‐model‐based algorithm for object manipulation tasks, which can be implemented with reasonable limited on‐line computations.Originality/valueThe proposed NMIC law is applied on an object manipulation task with three cooperating PUMA 560 manipulators while two of them are equipped with a remote compliant centre.

A New Approach on Object Slippage Control in a Cooperating Manipulators System

Considering slippage in the end-effectors of a set of two cooperating manipulators grasping an object, this paper presents a new dynamic modeling and control synthesis of grasping phenomenon. This dynamic modeling is based on a new formulation for frictional contact where equality and inequality equations in the standard Coulomb Friction model are converted all to a single second order differential equation with switching coefficients. Accuracy of the friction model is verified by comparing its results with those of SimMech. Then equations of motion are reduced to conventional form for nonconstrained system. Assuming the new reduced order system to be BIBO, internal stability of the whole system is analyzed. In the control synthesis of the system a multi phase controller is utilized to control the trajectory tracking of the object as well as slippage control of the end-effectors on the object surfaces. For the proposed controller, a proof is given for system stability and its performance and robustness are shown numerically. The results show superiority of the method and its desirable and excellent performance.