3. Inverse coordinate changes

The end device of a robot manipulator must perform movements and/or exert forces in a reference frame that is linked to the operating space (the workshop). The operator who programs a robot using advanced [5] software provides it with instructions defined in this space. On the other hand, even if the robot is equipped with external sensors (position, force) enabling it to be controlled locally to the task, its basic control systems are looped on information from its internal (joint) sensors, measuring more or less directly the q _i and/or the g _i . The robot's control cabinet must therefore contain a module (a program implemented on a digital computer) which calculates the setpoints to be sent to the "articular" servo-controls as a...