Modelling, parameters optimization and control of a Series Elastic Actuator for collaborative robotic applications

In classical robotic applications, actuators are preferred to be as stiff as possible to make precise position movements or trajectory tracking control easier. The superior power-to-weight ratio, force-to-weight ratio, compliance, and control of muscle, when compared with traditional robotic actuators, are the main barriers for the development of machines that can match the motion, safety, and energy efficiency of human or other animals. One of the key differences of these systems is the compliance or spring-like behaviour found in biological System.The capability to store and release energy is the game-changing factor in these fields. Collaborative robots are machines specifically designed to share the workspace and cooperate with the human operator in a safe manner.To guarantee safety also in presence of sensor/control faults and enhance physical human-robot interaction, a recent research trend is investigating the possibility to replace traditional stiff actuators with innovative compliant actuators.Collaborative robots equipped with compliant actuators have been demonstrated to be very effective for safe human-robot physical interaction.Current robotic systems with compliant actuators have many different implementations with different principles.The ambition of this thesis is to identify a reasoned strategy to approach the compliant actuator design systematically from the analysis of the desired task to derived use-cases.This thesis gives insights of the design process from the analysis of the desired tasks identifying the relevant attributes and their influence on the selection of different components such as motors, sensors, and springs. Furthermore, the design contradictions during the engineering process are explained in order to find the best suiting solution for the given purpose.Finally, the dependencies of control, models, sensor setup, and sensor quality are addressed.