The Effect of Quantization and Coulomb Friction on the Stability of Haptic Rendering

Rendering stiff virtual objects remains a core challenge in the field of haptics. A study of this problem is presented, which relates the maximum achievable object stiffness to the elements of the control loop. In particular, we examine how the sampling rate and quantization of position measurements interact with the inertia, natural viscous, and Coulomb damping of the haptic device. The resulting stability criterion generalizes previously known conditions. Simulations and experimental results support the theoretical analysis based on the passivity and describing function approaches.