Inverse dynamics control of a humanoid robot arm

Nowadays, humanoid robot technology is studied extensively around the world. These humanoid robots can reach the places that wheeled robots cannot and can perform complicated tasks with their two arm manipulators. Experimental studies are being conducted for humanoid robots. Interacting with environment, cooperation with humans and executing human-like motions for various tasks are the key objectives of these studies. Control of the manipulators of humanoid robots require a dynamic model based control for fast movement cases. As the manipulator is supposed to move in a cluttered environment, task space control inverse dynamics control is a suitable control policy for this scenario, where the motion of the end-effector can be predicted during the execution of the desired trajectory. The humanoid robots consist of a high number of actuators and sensors. To control the robot, sensor processing, motion planning and actuator control need to be done simultaneously. Thus, the software of these robots consist of multi-processes and scheduling to handle this problem. ROS (Robot Operating System) is an open-source operating system that has software libraries and tools for such robotic applications. It offers both simulator and hardware interface, alongside state-of-art algorithms. A software that runs on ROS consists of multiple processes called 'nodes'. Each node handles a different task, runs at a specified frequency and communicate with each other. This architecture eases the programming and enables use of open-source libraries in separate nodes in a plug-and-play way. Gazebo is an open-source dynamic simulation environment that enables the simulation of many type of robots such as full body humanoids with various sensors and environment interaction. Gazebo has interface with several platforms, including ROS and it offers several dynamic engines and number of transmissions, but not all of them are supported by ROS at the moment. ITECH Arm is a six degrees of freedom humanoid robot arm built in Mechanical Engineering Automatic Control Laboratory of İstanbul Technical University. The purpose of this thesis is creating a generic kinematics and dynamics library for the Automatic Control Laboratory, writing the software packages using this library for the ROS integration of the robot arm and finally implementing task space inverse dynamics control of ITECH Arm in Gazebo simulation environment. This thesis consists of six chapters. In the first chapter, purpose of the thesis, literature review and mechanical-software properties of ITECH Arm manipulator will be mentioned. In second chapter, kinematic and dynamic modelling of a robot manipulator is presented. The geometric, kinematic and dynamic models of ITECH Arm manipulator are derived. In chapter three, Robot Operating System is introduced. The software architecture and capabilities of ROS are mentioned. Integration steps of ITECH Arm to ROS environment and interfacing ROS and Gazebo simulation environment are described. In fourth chapter, trajectory generation for robot manipulators is mentioned. Several robot control methods are discussed. Implementation of task space trajectory tracking with inverse dynamics control algorithm on ITECH Arm is described. In chapter five, simulation results of circular trajectory for with and without payload cases using various gain sets and controller frequencies are presented. Also, as an example task, a pick and place scenario results are appended. The simulation results are discussed. In sixth and the last chapter, all the work done in the thesis is summarized and suggestions for future works are presented.