Assembly and Motion Planning to Build Soma Blocks Using a Dual-arm Robot

Abstract

This thesis presents a planner that integrates the assembly sequence planning and motion planning to perform the task of assembling soma blocks using a dual-arm robot. The input to the algorithm includes the mesh model of the soma blocks, the model of the gripper, and the initial and final poses of the soma blocks. The output of the algorithm is a set of instructions that gets interpreted by the motion planning algorithm to guide the two arms on how to assemble the blocks together; including the call to the second arm to stabilize the soma block during the assembly. The algorithm proposed in this thesis can be referred to as a grasp elimination algorithm. The algorithm, first, calculates a set of grasps for a given soma block based on the operator’s set attributes. Afterwards, the algorithm tries to filter out all the grasps that are in collisions. From among the remaining grasps, it attempts to find a solution to utilize either of the handover grasping, direct placement, and/or single-arm part manipulation on the surface to complete the assembly. Regarding the output of the planner, it has to be noted that the output solution might not be the ideal solution, rather it will be the first solution that minimizes the usage of the second arm to stabilize the assembly, and with a preference of assembling through approach direction from above. The contributions done through this thesis are reducing the complexity of motion planning through the calculations of the hand orientations during the assembly process. Furthermore, the grasp definition and elimination that has been recommended in this thesis have also proved to be efficient. Especially, the way the grasps are defined in this document helps immensely with filtering out the unwanted grasps. The two parts of assembly and motion planning have also been integrated together, and it can easily be extended to any type of manipulator or two fingered hand-gripper. Keywords: Assembly sequence planning, Grasp planning, Manipulation planning, re-orientation grasp planning, handover grasp planning