A novel design of series elastic actuator using tensile springs array

Abstract

Series elastic actuator (SEA) has already been used in robotics, especially the human-robot interaction field, to acquire compliance and force sensing ability. However, achieving a SEA design with linear and consistent elastic properties while having low friction, minor hysteresis, and good compliance is still challenging. In addition, the inherent conflict between good compliance and high bandwidth must be appropriately handled in the design. This paper proposes a newly designed compliant actuator with a novel elastic component using a tensile springs array. The unique geometry of the spring array enables SEA's consistent rotary stiffness within the whole working range while having trivial friction and hysteresis. We adopt PID and sliding mode control to evaluate the device's performance. It can be verified that the SEA has a constant low rotary stiffness of 1.13 Nm/deg bringing good compliance while having a torque tracking bandwidth of 7 Hz. These desirable properties enable our device to provide compliant, smooth, and predictable output to meet human-robot interaction requirements.