A modular soft robotic arm with embedded tactile sensors for proprioception

— Soft robotic arms are designed to execute dexterous tasks safely in cluttered environments due to their inherent compliance and infinite degrees of freedom. Closed-loop control requires proprioceptive sensing to retrieve the spatial configuration of the robot. However, the integration of soft sensing in the soft continuum body is still an ongoing challenge. In this paper, we present a highly integrated pneumatically actuated soft robotic arm that consists of 1) an omnidirectional actuator design for multi-material 3D printing, 2) a modular approach with fast assembling connectors and 3) a tactile sensing array embedded in the joint of each module. The in-joint placement of the tactile sensing array is used to map the variation of stress distribution between the two connected modules and the posture of the actuator with learned k-nearest neighbors regression. The experimental results showed that the method estimated the posture of a three-segment soft arm with a mean error of 5.64 mm for the tip location.