A Modular Soft Robotic Arm with Embedded Tactile Sensors for Proprioception

Soft robotic arms are designed to execute dexter-ous 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 configu-ration 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.