Motion Planning for Nonprehensile Object Manipulation Using Novel 5-Bar Linkage

Abstract

Nonprehensile manipulation is a concept of performing a manipulation task without the need for grasping and is a common mechanism found in nature, such as the dung beetle, to manipulate large and heavy objects across an environment. This concept, when applied to a robot, allows objects that are normally too large or heavy to be grasped, to be manipulated by exploiting a robot’s inherent locomotion unit through motion planning. This article presents a nonprehensile manipulation planning method for QuadRunner, a robot that utilizes a modified 5-bar mechanism to achieve hybrid locomotion and latching. When QuadRunner’s leg is in its latching configuration, it can securely connect to an object and complete a desired manipulation task. When the object’s height exceeds its leg workspace, QuadRunner is capable of leaping into the air and transiting into the latching mode to attach to an object to complete a manipulation task. Here, we introduce a motion planning model for QuadRunner to push and its 5-bar leg to realize the various necessary modes. Next, the system constraints are described, and how it was used to generate feasible robot motion paths to perform a desired nonprehensile manipulation. Finally, the leaping mode of QuadRunner is explained in detail. Experimental results show that QuadRunner can reliably leap to attach to an object of 43 cm in height, under the constraint that its most extended leg length is 22 cm.