Free-flying Space Robot Research Articles

Nonholonomic path planning of space robots via a bidirectional approach

The path planning of nonholonomic motion of space robot systems is discussed. A space vehicle with a 6-DOF (degrees of freedom) manipulator is described as a nine-variable system with six inputs. It is shown that, by carefully utilizing the nonholonomic mechanical structure, the vehicle orientation in addition to the joint variables of the manipulator can be controlled by actuating only the joint variables. The nonholonomic mechanical structure of space robot systems is shown. A rigorous mathematical proof of the nonholonomic nature of the free-flying space robot systems is provided using Frobenius's theorem. A method for nonholonomic motion planning for space robot systems is established by using a Lyapunov function.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Method of Attitude Control for Space Robots. An Approach Using a Neural Network.

A free-flying space robot consisting of a satellite main body and manipulator arms is expected to perform lmportant tasks in space. The attitude of the satellite changes when the manipulators are operated. This means the orientation angles would be controlled by an appropriate planning of the trajectory for the manipulators. For good robot performance, trajectory planning methods are required to control the orientation angles of the satellite. In this paper, a neural network is employed to generate the trajectory for the manipulators to control the orientation angles of the satellite and simultaneously to minimize the operational efforts. The proposed algorithm is applied to a free-flying robot with a simple two-link manipulator. By numerical simulation, the optimal trajectories are computed for any change of the orientation angles, and the effectiveness of the proposed algorithm is verified.

自律型宇宙ロボット地上実験装置ＡＳＲＯＴの開発

We developed a two dimensional operation testbed for an autonomous free-flying space robot such as an orbital maneuvering vehicle. This system is named ASROT (Autonomous space robot operation testbed) . Basically, ASROT consists of a satellite robot, a target, a host computer and a planar base. A host computer is only used for observation and data gathering of the system. A satellite robot is a satellite which can establish various tasks with a manipulator. A satellite is 620mm (W) ×805mm (H) ×620mm (L) . Its weight is 120 kg. This system is floating on a planar base using air bearings, and is able to fly around using thrusters for position control and a control moment gyro for attitude control. A manipulator is a flexible arm and 1.4m long. This paper proposes an operating system which is needed for real time autonomous control. A satellite robot installs hardware systems such as vision systems, board computers, image processing units, and software systems such as algorithms for path planning.