Development of two degrees of freedom deterministic parallel robotic arm unit

This paper investigates the development of an exact constraint parallel robotic arm unit. In addition to the advantages of simple structure and compact size, the six points exactly constrained parallel robotic arm unit is both statically and kinematicaly deterministic, thus is more suitable for precision position application. Theoretical analysis based on the principle of exact constraint is given to explore the degree of freedom and constrain pattern of the parallel robotic arm unit. Furthermore, the orientation adjusting principles at various input statuses are presented to promote the orientation process. The performances of the fabricated parallel robotic arm unit are confirmed by experimental studies. As the parallel robotic arm unit has relatively small workspace, numerous parallel robotic arm units, with various sizes, should be cooperated to achieved the desired workspace.