Haptic Manipulation of Serial-Chain Virtual Mechanisms

Abstract

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 null space 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.

Master-Slave Coordination Using Virtual Constraints for a Redundant Dual-Arm Haptic Interface

“…Attractive and repulsive potential fields have been used to introduce virtual constraint forces, which help the operator to keep the movements within a region of interest or to avoid singular configurations [22]. In virtual reality applications, some researchers have employed virtual spring-damper elements to penalize user motion along the direction resisted by the virtual mechanism [23].…”

“…Therefore, for positive definite K d and K p , the solution of (24) converges asymptotically to zero. By substituting (23) into 18, we observe how the nonlinear feedback from both arms contributes to the control law. Assuming an accurate model of the arms and after gravity and Coulomb friction compensation, these control laws are applicable.…”

Haptic manipulation of virtual linkages with kinematic loops

“…The present work employs a control architecture whereby separate controllers render inertia, joint constraints and contacts to users [5]. This control architecture, schematically depicted in Fig.…”

“…Increased physical accuracy of the haptic simulation of linkages has also been sought via modeling collisions in [18], [3]. The haptic rendering of the joint constraints of serial-chain VTs has been implemented via proxies with first order dynamics in [13] and via a controller acting along the constrained directions in [5]. Apart from the haptic manipulation of a VT with a kinematic loop reported in [14] and based on an application-specific simulation and haptic rendering algortihm, mostly haptic interaction with serialchain VTs has been investigated to date.…”