A parallel-processing controller architecture for force control of an industrial robot

A controller for end-effector forces must be powerful enough to handle hybrid position/force control algorithms and inverse dynamics, as well as a six axis multi-variable inner-loop controller. It must have the capability to acquire data from up to twenty-one sensors and output to six actuators. It must allow flexible inter-process communications as well as providing a simple interface between the various levels of control. A fast software development environment is desirable and floating point arithmetic greatly eases data overflow and scaling problems. The author has developed a transputer based real-time controller and measurements show that it should fulfil the computational requirements for force control of an industrial robot. A pipeline architecture has been chosen for data distribution, and show to introduce a negligible delay compared to the sampling period. Reliance on commercially available analogue interface hardware has proved to be a problem, but simple boards can be built to overcome this limitation