Alireza Naghsh - Department of Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Farid Sheikholeslam - Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan, ۸۴۱۵۶-۸۳۱۱۱, Iran
Mohammad Danesh - Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, ۸۴۱۵۶-۸۳۱۱۱, Iran

This paper presents a stable new algorithm for force/position control in robot manipulators. In this algorithm, position vectors are measured by sensors and then used in the control law. Since using force sensor has some issues such as high costs and technical problems, an approach is presented to overcome these issues. In this respect, force sensor is replaced by an adaptive fuzzy estimator to estimate the external force based on position and velocity measurements. In this approach, force can be properly estimated using universal approximation property of fuzzy systems. Therefore, robots can be controlled in different environments even when no exact mathematical model is available. Since this approach is adaptive, accuracy of the system can be improved with time.  Through a theorem the stability of the control system is analyzed using Lyapunov direct method. At last, satisfactory performances of the proposed approach are verified via some numerical simulations and the results are compared with some previous approaches.

Force/Position control, Adaptive, Fuzzy estimation, Robot manipulator, stability