Energy-based approach to develop soft robots
Chun, Ho-Tak Derek
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Soft robotic systems offer advantages against rigid robot systems in applications that involve physical robot-human interactions, unstructured or extreme environments, and manipulating delicate objects. Soft robots can offer inherently safe operation and adapt to unknown geometry of the environment or object. The current soft robot development approach is an empirical approach starting from a type of soft actuation technology, whereas the development of rigid robots can start from a top-level task in a System Engineering framework. The rigid robot developer can select from well-defined components to construct the task-orientated system. Soft robots are relatively novel systems compared with rigid robots and do not have well-defined components due to a wide range of soft actuation technologies. The initial choice of soft actuation technology places constraints on the system to perform the task. Soft robotic systems are not widely used despite the advantages compared to rigid robots. In this thesis, I study an abstraction approach to enable a System Engineering framework to develop soft robotic systems. My research focus is on an energy-based approach that encompasses the multi-domain nature of soft robotic systems. The impact on the final system from the energy transfer characteristics of the initial choice of the soft actuator has not been fully explored in the literature. I study how energy, and rate of energy transfer (power), can describe different components of each type of soft actuation and how the total energy can model the top-level system. This thesis includes (i) a literature review of soft robots; (ii) an abstraction approach based on bond-graph theory applied to soft actuation technologies; (iii) a port-Hamiltonian theory to describe the top-level soft robotic system, and (iv) an experimental application of the approach on a type of soft actuation technology. In summary, I explore how energy and rate of energy transfer can provide the abstraction approach and in time provide the well-defined components necessary for task-orientated design approaches in a System Engineering framework. In particular, I applied the approach to soft pneumatic systems for additional insights relevant to the development of future task-orientated soft robotic systems.