1. Field of the Invention
This invention relates to a multi-articulated arm mechanism suitable for use in working robots and manipulators, and more particularly to an arm mechanism which has high rigidity against operational reaction forces or other loads which are imposed on the arm during operation.
2. Description of the Prior Art
In general, a multi-joint robot has a series of arms with articulated joints on a fixed base or pedestal, performing an assigned job by a working tool which is attached to the distal end of the arms. Therefore, the force applied to a work is invariably reflected by a bending moment acting on the base portion of the arms, causing operational errors by arm flexure which occurs to a greater degree with longer arms. For this reason, the application of the multi-articulated robots has been limited to those fields in which the robots can perform a required job without contacting the work, free of the reaction forces as in welding and coating operations. They have been considered unsuitable for operations like grinding or other machining operations which involve reaction forces or operations which require attaching a testing device or other devices of a large weight at the distal end of the arm.
Nevertheless, the multi-articulated arm mechanism is superior in operability to the arm mechanisms of the perpendicular coordinates system or the parallel type arm mechanisms, and accordingly extremely convenient for performing complicated operations, for example, the operations which have to be carried out in a narrow limited space or the operations which require evasion of obstacles.