Friction compensation and null space control of a redundant robot

Collaborative robotics is an emerging sector. Multiple applications are possible for collaborative robots and one of them is manual guidance performed by a human operator. In this thesis the robot arm taken under consideration is the Franka Emika Panda robot. This thesis has the goals of finding the friction model of the joints of the robot in order to compensate correctly the friction, and to study the null space of the robot so as to improve the motion of the robot in the operational space and to provide a safety measure to protect the human operator working with the robot. The work is divided into six chapters. In the first chapter an overview of the robot and its integrated software and controller is given. The second chapter presents theoretical basics necessary for the null space study. In the third chapter the friction model is obtained and the resulting behaviour of the robot is shown. The fourth chapter deals with the null space control of the robot, presenting several strategies to improve the performances of the robot. In the fifth chapter the results of two tests are presented, showing that the forces that the human operator needs to apply to guide the robot have acceptably small values for manual guidance applications. The last chapter shows an introductory test on the usage of an IMU sensor suit to improve the null space behaviour of the robot.