Manipulation of an object exceeding load capacity using virtually unactuated joints (1st report, concept and method to realize virtually unactuated joints)

The load capacity of a manipulator depends on a load capacity of a low output joint or load capacities of some low output joints of the manipulator. Even if a manipulator could not handle an object because of its load capacity, some of its joints still have enough capabilities for handling of the object. In this paper, we propose a method to handle an object using available joints of the manipulator by introducing virtually unactuated joints. The virtually unactuated joints are controlled so that no load will be applied to the joints. Experiments illustrate the validity of the method proposed in this paper.