SenSation : A New Translational 2 DOF Haptic Device with Parallel Mechanism

We propose a new two -degree of freedom para llel mechanism for a haptic device and will refer to the mechanism as the SenSation. The SenSation is designed in order to improve the kinematic performance and to achieve static balance. We use the pantograph mechanisms in order to change the location of active joints, which leads to transform a direct kinematic singularity into a nonsingularit y. The direct kinematic singular configurations of the SenSation occur near the workspace boundary. Using the property that position vector of rigid body rotating about a fixed point is normal to the velocity vector, Jacobian matrix is derived. Using the vector method, two different types of singularities of the SenSation can be identified and we discuss the physical significance of each of the three types of singularities. We will compare the kinematic performances(force manipulability ellipsoid, kinematic isotropy) of the SenSation with those of five-bar parallel mechanism. By specifying that the potential energy be fixed, the conditions for the static balancing of the SenSation is derived. The static balancing is accomplished by changing the center of mas s of the links.