Enhanced Energy Harvesting from Nonlinear Oscillators via Chaos Control

Modern electronic devices require less energy on-board and could be powered by energy harvested from the environment. Broadband vibration energy harvesting is one of the widely explored options for powering such devices. One such harvester that exploits this technique is the nonlinear inverted elastic pendulum. This system has a double-well potential and can undergo large amplitude inter-well oscillations. Piezoelectric patches, pasted near the base of the beam, convert these mechanical oscillations into electrical energy. However, the large amplitude responses can deteriorate over time into low energy chaotic oscillations, thereby reducing the harvested power. Under such conditions, forcing the system to follow a high energy orbit would improve the energy harvested from the system. However, it is not wise to invest a large control force to stabilize the high energy orbits. This manuscript aims to exploit the chaotic nature of the system to stabilize the unstable periodic orbits. The chaotic behavior of the system allows even small perturbations to alter its response dramatically. Taking advantage of this property, a low power controller, based on the method of Ott, Grebogi, and Yorke (OGY), is used to stabilize the unstable high energy periodic orbits. The control strategy is implemented on the linearized system, about the operating point corresponding to the chosen orbit. LQR is used to determine the optimum control force. The devised strategy is numerically simulated, which favors the implementation of OGY control to improve their energy harvesting capabilities.