There exist configurations of parallel cable-driven mechanisms (CDM) within their wrench closure workspace (WCW) for which they may become unstable when their cables are subjected to internal forces due to prestress or external loads. With the goal of avoiding such configurations, the prestress stable WCW (PSWCW) is defined as a subset of the WCW where an increase in the prestress level leads to an increase in the overall stiffness of the mechanism. A genetic algorithm is used to optimize the geometry of planar parallel CDMs with four cables with the objective of reaching a desired PSWCW. Results are obtained that may guide the designer in the preliminary selection of mechanism dimensions and cable connectivities.

Tensegrity mechanisms have the advantage of being relatively lightweight due to their extensive use of cables and springs. In this work, a novel planar modular 2-DoF tensegrity mechanism that is actuated by cables is introduced. The modular architecture of the mechanism gives it increased flexibility while using cables for the actuation leads to large reachable workspaces. An analysis of the mechanism's statics and kinematics is performed for the case where no external loads are acting