The virtual handle [force-reflecting mechanisms]

Many force-reflecting mechanisms with two to six degrees of freedom have been designed in the past for master-slave and haptic applications. Both serial and parallel mechanisms increase in mechanical, modeling and control complexity at a greater-than-linear rate with additional degrees of freedom. On the other hand, using two or three reduced-dof mechanisms only multiplies the complexity of each individual system by the number of mechanisms. The concept of the virtual handle is based on using two or three mechanisms each with three or four dofs, with a digit of the operator's hand operating one each. The mechanisms can be controlled in such a way that the operator feels as if a virtual device with a greater motion freedom than each individual mechanism is being grasped. The virtual handle can be made to emulate the operator's tool of choice, including a gripper, with the necessary number of virtual pushbuttons.