SpringGami: Spring-driven Origami-based Actuators with Bidirectional Motions and Built-in Position Feedback

Despite the increasing popularity of soft actuators, their real-world applications are limited due to their complex actuation systems and sensing strategies. This paper presents a new type of compliant actuators, SpringGamis, which are characterized by easy fabrication, bidirectional motions, and built-in position feedback. For the basic design of a SpringGami, a spring is used to bidirectionally actuate an origami skeleton to realize compliant motions, and partial constraint of the origami skeleton can conveniently program the motion profiles. By measuring the displacement of the spring tip and spring inductance, the actuator deformation can be obtained. Theoretical analysis is conducted to illustrate the couplings among the spring inductance, spring tip displacement, actuator deformation, and output force, and experiments are also implemented to demonstrate the accuracy of the sensing strategy. For potential applications, grippers based on SpringGamis are developed to grasp delicate objects with different shapes, weights, and textures. The results of this paper provide a simple and practical solution to develop flexible compliant robots with sensory feedback and compactness.