Effect of internal forces on stiffness of closed mechanisms

In cooperative motion of multi arm robotic mechanisms or in the case of a grasping operation by robot hands, internal forces which balance inside the mechanism are generated. The research described deals with such forces and their effects on closed mechanisms. Internal forces can be generated by both potential and non-potential driving forces. In either case the structural stiffness of the mechanism changes due to the internal forces as the mechanism moves. When the internal force is compressive, the mechanism may have negative stiffness leading to a problem similar to the stability problem in the grasping operation.<>