Minimum Energy Demand Locomotion on Space Station

The energy of a space station is a precious resource, and the minimization of energy consumption of a space manipulator is crucial to maintain its normal functionalities. This paper first presents novel gaits for space manipulators by equipping a new gripping mechanism. With the use of wheels locomotion, lower energy demand gaits can be achieved. With the use of the proposed gaits, we further develop a global path planning algorithm for space manipulators which can plan a moving path on a space station with a minimum total energy demand. Different from existing approaches, we emphasize both the use of the proposed low energy demand gaits and the gaits composition during the path planning process. To evaluate the performance of the proposed gaits and path planning algorithm, numerous simulations are performed. Results show that the energy demand of both the proposed gaits and the resultant moving path is also minimum. 1. Introduction The application of robots in space exploration becomes more advanced. For extravehicular activities (EVA) in low Earth orbit, most of them are designed as a chain-like manipulator which is suitable in performing tasks such as mechanical assistance, capturing operations, monitoring, and satellite maintenance [1]. Shuttle Remote Manipulator System (SRMS) [2, 3], Engineering Test Satellite No. 7 (ETS-VII) [4], the main arm (MA) and the small fine arm (SFA) of Module Remote Manipulator System (JEMRMS) [5], European Robotic Arm [6] and Space Station Remote Manipulator System (SSRMS), or Canadarm 2 [7] are typical examples for space manipulators. In addition to manipulation tasks, they are capable of navigating on the exterior of a space station. For the locomotion on a space station, two major gaits are commonly used which are inchworm gait and turnaround gait. Canadarm 2 is a typical example which uses inchworm gait for locomotion. Different from the inchworm gait, the turn around gait is another commonly used gait in conventional truss climbing robots such as Shady, Shady 3D, and Handbot [8–10]. For the conventional long limbs design of space manipulators, a larger joint torque is required to drive the arm’s swing motion in conventional gaits. As a result, these conventional gaits are regarded as a high power demand motion. Since the energy source of a manipulator is from the attached space station, the minimization of energy consumption of a space manipulator is crucial to maintain normal functionalities of a space station. Without modifying the joint configuration of existing manipulators, we propose novel gaits for space