抄録
This paper describes representation of constrained motion and dynamic control of manipulators under constraint.
When an object has fewer than 6 degrees of freedom (dof), its motion is partially constrained and its position and orientation cannot be arbitrarily determined. Constrained motion for dof=n can be simply represented by n position variables corresponding to the number of degrees of the object's degrees of freedom of motion. Here we introduce six sets of variables for representing an object's position and forces acting upon it. The six sets are as follows.
n sets -n position variables and n supplementary force variables
6-n sets-6-n force variables and 6-n supplementary position variables
Conditions of constraint are satisfied by assigning constants to the supplementary position variables and zero to the supplementary force variables. The position and orientation of the object and forces acting on it are represented by the n position variables and 6-n force variables.
An expression defining motion of the object-manipulator system is formulated in terms of these 12 variables. Position is controlled by a servo mechanism based on real time calculation of position variables, error, and dynamic manipulator joint torque. Force is controlled by driving the manipulator joints with statically determined torque.
