2013 Volume 26 Issue 2 Pages 74-83
Torque-unit Manipulator (TUM) is a design concept of space manipulator. A device which is called “torque unit” is equipped on each link of a kinematic chain whose joints are all free. The “torque unit” can be made easily of a rotary actuator and a disc. TUM is a kind of nonholonomic system and the angular velocity of each disc at each time depends on the trajectories of the links. Controllability has been considered to control the position of each link to desired position and the angular velocity of each disc to desired constant value, by planning the trajectories of the links for 2-dimensional N d.o.f. TUM. It consequently has been shown that it is impossible to control the angular velocity of each disc to desired constant value since TUM has a first integral. However the first integral allows us to control the angular velocities of the all discs to a constant value of zero. Then, a control strategy is considered and described based on the results of the consideration on the controllability of all state valuables of TUM in this paper.