Mizuho Shibata, and Shinichi Hirai

Abstract:
To analyze the stability of dynamic control through a soft interface -the viscoelastic material between a manipulating finger and a manipulated object- we model dynamic control through the soft interface in continuous-discrete time. We then formulate dynamics using a modified z-transform in continuous-discrete time for feedback and feedforward control. We show that system stability depends on the viscoelasticity of the soft interface for feedback control. The relationship between material viscosity and sampling time in critical stability is not monotonous, a phenomenon we analyze by root locus. We compare stability analysis by the modified z-transform, simulations based on the Runge-Kutta method, and a regular z-transform, demonstrating that the relationship is specific to a continuous-discrete time.

Keywords: soft interface, dynamic object manipulation, viscoelasticity, continuous-discrete time system, modified z-transform