Regenerative tensegrity structures for energy harvesting applications

This paper investigates the potential of controlled tensegrity structures as a means for electrically generating and storing energy injected into the structure by external disturbances. An approach is presented for the integration of linear, regenerative actuators into tensegrity structures as supplemental active bars. By operating these actuators as generators, mechanical energy absorbed from the structure during periods of external excitation is converted to electrical energy. Through proper control of the power-electronic network to which the actuators are connected, a fraction of this energy may be recovered and delivered to a storage system or an external power grid. A generalized model for a regenerative tensegrity structure with arbitrarily-many actuators is presented, which accounts for electrical dissipation in the actuators and associated electronics. Issues pertaining to actuator selection and power-electronic control are discussed. An approach is presented for the design of simple collocated linear velocity-feedback controllers for systems with one actuator, such that the rate of structural energy extraction is optimized for the steady-state closed-loop response to an external disturbance. The approach is illustrated in a simulation example for a small-scale system. Extensions are discussed in which a regenerative tensegrity structure is used to harvest energy from the motion of ocean waves.