Compliant Manipulation for Autonomous Search and Rescue Operations
Éamon Barrett is a PhD student in the research group Robotics and Mechatronics. His supervisor is prof.dr.ir. S. Stramigioli from the faculty of Electrical Engineering, Mathematics and Computer Science.
Autonomous robotic systems are performing an ever-increasing variety of tasks that can not only make our lives simpler, but sometimes even help save them. Disaster response, and search and rescue missions are such an application, where robots can greatly support human rescuers by expanding their capabilities and relieving them of dangerous or routine tasks. This is the goal of the SHERPA project, in which a mixed ground and aerial robotic team with a high degree of autonomy helps to locate missing or injured people in a hostile alpine environment. A compliant manipulator herein services small-scale UAVs, a collaborative task that involves dexterous manipulation in an unfamiliar environment, and potentially impacts or collisions. For this reason it is equipped with Variable Stiffness Actuators VSAs, which allow it to tune its mechanical end effector stiffness, and to interact with the environment in a passively compliant way. This thesis presents the design and control of this novel manipulator and its components, its integration with the other agents of the SHERPA team, and experimental validation of the mission.
A core component of this compliantly actuated system are a number of VSAs, which allow safe and dexterous interaction with the environment. The analysis of their design focuses on modeling the internal energy flows and optimization of their mechanical energy storage elements. The arm’s actuation topology and its effect on the achievable workspace compliance are investigated, and a thorough mathematical framework for solving associated control problems introduced. The mechatronic design of the robotic arm and its components is presented, including its kinematics, the design of several differentially coupled joints, and a custom gripper, developed to latch into an interface mounted on the UAV to ensure robust grasping under misalignment. The arm has been successfully integrated with the rest of the SHERPA team through a control and delegation framework which allows the agents to autonomously plan and execute complex missions. The completion of the arm’s main task of replacing a landed UAV’s battery is used to demonstrate the system’s capabilities, and underlines the role such automated systems can play in supporting and improving search and rescue operations.
A number of research questions relevant to the fields of compliant manipulation, collaborative robotics, and the coordination and control of robotically aided search and rescue operations have been addressed in the course of this research, resulting in a novel robotic manipulator that demonstrated its ability to perform complex collaborative operations.
