Coordinating Control of a Special Joint Structure with More Servos than Degrees of Freedom

• Main Author: Fredrik Dessen
• Format: Article
• Language: English
• Published: Norwegian Society of Automatic Control 1987-07-01
• Series: Modeling, Identification and Control
• Subjects: Robot manipulators; redundancy; coordinate transformation; force control
• Online Access: http://www.mic-journal.no/PDF/1987/MIC-1987-3-5.pdf

A joint mechanism for use as a general building block in manipulators with a very high number of degrees of freedom is introduced. It consists of 3 servos driving a 2 d.o.f. universal joint by means of wire. A coordinate transformation set is developed, which includes positional, velocity and force transformations. Both direct and inverse transformations are presented. Special attention is given to the inverse force transformation which is obtained using linear optimization. The solution in this case is also shown to be valid for a more general class of constrained non-linear optimization problems. An example is given of the use of the coordinate transformation set; a joint control system including servos under internal force control.