Force Control of a robot manipulator using a real-time PC- based Controller

Abstract

This master thesis is based on an autonomous wheeled mobile manipulator project, directed in Tampere university of technology (TUT). In the beginning, we carried out a comprehensive study on the linux-based real-time operating systems, meanwhile existing limitation in the real-time operating system and real-time consideration in the programming of the control application has been surveyed in more details. Then, we studied force control strategies and control theories of the manipulators under contact forces. After that, manipulator dynamic equations and internal motion control loops were simulated using Simulink environment of Matlab. In this step, three scheme of controller with different area application were designed and was simulated on the manipulator Simulink model. The implementation part is based on the rapid prototyping method using Matlab/Simulink code generation products, firstly, the interfacing software between the manipulator joint actuators and the main controller software which is run in the RTLinux Xenomai was developed. In the next step, a similar interfacing application was developed for acquiring force data from the force torque sensor. In the next step, force torque sensor was calibrated using a calibration method according to gravity effects, then calibrated data was provided as measuring(sensory) input of the force controller software. In the final step, force control loop was closed around the motion controller loop and stiffness control scheme was achieved.