| For a manipulator operating
in a hazardous or remote environment, an important concern is its capability
after a component failure, since retrieval or repair is not always possible.
Methods have been presented in the literature for optimizing capabilities
after specific types of failures. However, techniques for achieving failure
tolerance when conversion between failure types is possible has not been
fully explored. This paper presents an approach to improving postfailure
performance by converting between locked-joint failures and free-swinging
failures through active braking. When a manipulator is moved slowly, gravitational
forces can be used to control the failed joint in free-swinging mode, allowing
the problem to be cast as a kinematic one. The validity of the kinematic
formulation and its implementation and global consequences are explored. |
