Lip Geometry-Constrained Smooth Sliding Path Planning for Robotic Negative Pressure Therapy on Extremities

Abstract

Negative pressure (NP) therapy with sliding suction is an effective method for limb lymphedema. Due to the caregiver shortage and the patients increase, the robotic NP therapeutic system with a variable-sized suction head can be used to help the lymphedema therapy. However, the varying complexity of different limb regions can affect the accuracy of the suction path. Moreover, the moving suction path should maintain smoothness to ensure therapeutic efficacy. Therefore, finding a smooth sliding path with highly accurate suction poses on the unstructured limb surface poses a significant challenge for robotic therapy. In this paper, a smooth sliding path planning method is proposed for robotic continuous suction in limb lymphedema therapy. The easily-sealed region is identified by comparing point normals to the lip’s suction angle, simplifying path planning to a 2D plane due to lip and limb flexibility. The conjugate gradient method optimizes the path with centroid distance and smoothness constraints. Finally, after the generation of suction poses under the constraints of the lip shape, a smooth sliding path along with lip pressure commands, is obtained to regulate the robot in performing continuous suction therapy. In the experiment, the manipulator with a variable-sized head has been used to finish 10 sliding suctions from different planning path. From the result, the robot could complete 6 times sliding suctions on the phantom arm.