Active Tensegrity Structure

Abstract

Most active structures involve direct control of single parameters when there is a closed form relationship between the response required and the control parameter. Building on a previous study of an adjustable structure, this paper describes geometric active control of a reusable tensegrity structure that has been enlarged to five modules with improved connections and is equipped with actuators. Closely coupled strut and cable elements behave nonlinearly (geometrically) even for small movement of the 10 telescopic struts. The control criterion for maintaining the upper surface slope has no closed form relationship with strut movement. The behavior of the structure is studied under 25 load cases. A newly developed stochastic search algorithm successfully identifies good control commands following computation times of up to 1 h. Sequential application of the commands through sets of partial commands helps to avoid exceeding limits during intermediate stages and adds robustness to the system. Reuse of a previously calculated command reduces the response time to less than 1 min. Feasible storage and reuse of such commands confirm the potential for improving performance during service.