Traditional robotics use stiff actuators, which are inherently unsafe to work with. Series elastic actuators were developed to deal with this issue, and provided a compromise between performance and safety metrics. By implementing a series elastic element, motor dynamics are decoupled and the system will have a limited bandwidth and thus reduced control, but increased safety. Additional benefits of the series elastic element are convenient and cheap force measurement, and the element can be used as energy storage. Non-linear series elastic elements are investigated to tackle the compromise, offering the safety and torque resolution of low stiffness actuators, with the higher bandwidth of high stiffness actuators.
Various concepts of non-linear series actuators will be considered, of which the most promising candidate will be chosen to design, implement and evaluate its performance. As a secondary objective the project tries to improve non-linear series elastic actuator performance without compromising stability in lower stiffness ranges with the use of control systems.