Haptic manipulation of serial-chain virtual mechanisms

This paper presents an approach for providing realistic force feedback to users manipulating serial-chain virtual mechanisms. In the proposed approach, a haptic device controller is designed that penalizes users' motion along the directions resisted by the virtual joints. The resisted directions span the nullspace the Jacobian of the virtual mechanism computed at the users' hand, and are derived via a singular value decomposition-based algorithm. Haptic numerical performance is achieved by computing the resisted directions on the graphics processor, and by using them on the haptics processor to derive the control signal that restricts users' motion as required by the virtual joints. The performance of the proposed approach is validated through experimental manipulations of links with unrestricted and with restricted motion within a planar virtual world.