Handling of an object exceeding load capacity of dual manipulators using virtually unactuated joints

The load capacity of a manipulator depends on a load capacity of a joint or load capacities of some 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 the handling of the object. We propose a method to handle an object using available joints of the manipulators by introducing virtually unactuated joints. The virtually unactuated joints are controlled so that no load will be applied to the joints. The introduction of the virtually unactuated joints make the available degrees of freedom of the manipulator less than that of the original manipulator. We propose a method to manipulate an object with dual manipulators having virtually unactuated joints. An experiment illustrates the validity.