A study on determining optimal base location of a serial manipulator mounted on a hexapod mobile robot

Abstract

A numerical analysis is carried out in this paper to determine an optimal location for mounting the base of a serial manipulator on a six-legged mobile platform, also known as legged mobile manipulator (LMM), in terms of its workspace, manipulability of the manipulator and foot forces’ distribution among the legs. In LMM, the multi-legged platform provides mobility, whereas manipulation is achieved by the robotic arm. The position of the manipulator on the mobile hexapod platform is very important in integrating this system, as it has a major impact on the performance of an LMM. For numerical analysis, the quantitative measure of each parameter is required. Thus, initially, the workspace of the LMM considering self-collision is quantified by generating a reachability map of the robotic system. Then, the stance-constrained Reach Jacobian of the combined robotic system is derived for the purpose of manipulability measure. Next, foot force-based stability margin is used to measure the foot forces’ distribution among the legs. All the abovementioned parameters are calculated at different pre-selected manipulator’s base locations on the hexapod platform. Finally, a numerical analysis combining these three parameters is carried out to find an optimal mounting location of the manipulator on the hexapod platform.