Energy conserving constant shape optimization of tensegrity structures

Tensegrity structures are remarkable constructions composed of non-touching compression members (e.g. tubes, bars, beams, struts) embedded in a mesh of tension members (e.g. springs, cables, tendons). Herein we present optimization methods that show that it is possible to actively reconfigure the tension members of a redundant tensegrity structure with zero net mechanical work, while maintaining the equilibrium shape of the structure. These methods are based on the dimensionality of the null space of the equilibrium conditions. We provide implementation details for compliant tensegrity structures and we apply them in two numerical experiments: stiffness/resonance frequency tuning and shape stabilization. The methods are relevant to structure stabilization (energy landscape control), vibration mitigation (modal control) and excitation (energy harvesting).