reactionless capture of a satellite by a two degree-of-freedom manipulator
- Paper number
IAC-08.C1.1.6
- Author
Ms. Patrizia Piersigilli, Italy
- Coauthor
Prof. Inna Sharf, McGill University, Canada
- Coauthor
Prof. Arun Misra, McGill University, Canada
- Year
2008
- Abstract
The objective of this work is the development of a new trajectory generation method, a reactionless trajectory generation strategy for a robotic manipulator mounted on a service vehicle so that it can capture a target satellite without the need for attitude control of the base during the arm operation. The motivation behind this research work arises from the following:
(1) Automation and Robotics will play a key role in many new space activities, but the challenge of autonomous robotic operations still remains.
(2) The trajectory generation techniques available to date have been designed for a servicing satellite whose attitude and position are controlled. This is not necessarily the best nor the cheapest option for overcoming the dynamic coupling between the manipulator and its non-fixed base which, if not taken into account, can result in the robot end-effector missing the target.
By reactionless trajectory generation strategy we mean a trajectory generation strategy developed under the constraint that the manipulator follows only those paths that do not disturb, or at least minimize the disturbances on the base supporting it. This strategy is based on the Reaction Null Space (RNS) method, originally proposed by Yoshida, because it allows on-line path generation and appears to be the most manageable for implementation within a trajectory generation algorithm. Developing trajectory generation algorithms is a complex task, and the addition of further constraints such as proper phasing so that the manipulator end-effector intercepts the target handle, and limits on joint rates and acceleration, makes it a real challenge.
Three novel algorithms, considering gradually more complex cases, were developed and implemented in Matlab. The first algorithm dealt with the simplest case in which the existence of intersections between the target handle trajectory and the end-effector reactionless path was investigated. This was followed by an algorithm that considered the relative velocity between the intercepting bodies. Finally the manipulator joint rate and acceleration constraints were imposed and the manipulator motion limitations due to the servicing satellite geometry were taken into account. The simulations carried out show that not only geometric intersections between the path of the target handle and the reactionless end-effector trajectories can be found but also that, with the last algorithm developed, it is possible to devise a reactionless capture trajectory satisfying all the constraints mentioned above, despite the complications that the use of the RNS equations implies.
- Abstract document
- Manuscript document
IAC-08.C1.1.6.pdf (🔒 authorized access only).
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