Compliant Spherical Joint Design for Reconfiguration of Variable Topology Truss

This paper presents the design of a compliant spherical joint for the Variable Topology Truss (VTT) system that enables topology self-reconfiguration. Self-reconfiguration is a common feature of modular robot systems. In a truss-type modular system, self-reconfiguration requires care to prevent collapse and control truss position for docking. This paper proposes maintaining structure stability while disconnecting truss members during reconfiguration by adding joint stiffness between members. Keeping the members in equilibrium allows predictive positioning to aid reconfiguration. In this study, we present the self-reconfiguration of a tetrahedral VTT system as a simple demonstration. The required stiffness value for the spherical joint mechanism was calculated by statics simulation. A joint and docking prototype is demonstrated with docking to show the feasibility of this proposed self-reconfiguration procedure.