A Passive RFC (Reaction Force Compensation) Mechanism Using Adjustable Piecewise Linear Stiffness of Pre-Compressed Springs

Nonlinear elements are used when a mechanical system has different performance requirements according to its positions. Piecewise linear system is widely used to investigate and to approximate nonlinear elements. So far, just springs with constant stiffness were used for passive, active or semi-active RFC (reaction force compensation) systems. In this paper, we developed an adjustable passive RFC mechanism for a linear motor motion stage using pre-compressed springs with piecewise linear stiffness. First, principle and related theory of the passive RFC mechanism using pre-compressed springs was introduced. Then, we modified a linear motor motion stage to install pre-compressed springs and the effect of a pre-compression of springs on the RFC performance was studied by free vibration test. Finally, the effectiveness of the adjustable passive RFC mechanism using pre-compressed springs was verified with simulation and experiment.