Acceleration based force estimation in series elastic actuator

With increasing of the needs to collaborate with humans throughout the industry fields, a series elastic actuator(SEA) has been developed which enable more compliance motion rather than conventional motor-based actuator. The device is equipped with spring inside, and it turns increased mechanical elasticity, allowing to react more flexibly to the external force, generated by external environments such as impact. In this point, it is important to measure well spring deflection. Encoder with a delivery mechanism such as the belts, the gear, and the wire is typically used for the purpose. The high-resolution encoder improves the performance of SEA, however, at the same time, it is expensive. To solve this problem, we proposed an estimating method for external force using acceleration sensor. In previous studies, external force observer using encoders were designed as a shape of the transfer function and state space. The performance of observer using acceleration sensor is compared to two previous algorithms.