Modeling and Simulation of 6DOF Robot Manipulators with Tactile Position-Force Control

In this paper, a joint position-force controller is used to control a 6R general-purpose robot manipulator. The manipulator comes into interaction with a spherical object in a numerically simulated environment. A controller has been implemented using the MATLAB Simulink software which uses the Simmechanics second-generation toolbox. A useful numerical contact model is used for modelling the interaction between the manipulator’s end-effector and the environment which generates the interaction feedback forces. The control algorithm presented in this paper is developed in the Cartesian space and the original control algorithm was modified to satisfy the desired input position in the base coordinate frame. The control algorithm was verified using a virtual environment, before hardware implementation. The novelty of the controller is determining the input tactile forces for the robot without actually causing a collision between the end-effector and the object in the environment which can lead to fracture and damage to the environment or the manipulator. The modeling process of interaction with the spherical environment was investigated using Simmechanics to model precise mechanical characteristics of manipulator that are unknown to the designers and provide a great advantage in the simulation for them. The considered position and tactile force were tracked successfully with good accuracy. The results show that the proposed manipulator system controls the position and force with more than 95% accuracy and the accuracy of desired tracing trajectory is 99%.