Vibration Energy Harvesting from Planar Excitations in Industrial Machines.

Vibration energy harvesting is a clean way to extract kinetic energy from the environment and convert it into electrical energy that can be used locally to power small electronic devices, like sensors and low-power electronic systems. A vibration energy harvester can be embedded into the transducer, allowing easy repositioning of the device, and providing a permanent power supply, with no need for batteries or cables. In industrial environments, machines in operating conditions can provide a large source of mechanical vibrations. The majority of energy harvesting devices that have been proposed in the literature use a single degree of freedom configuration, where an oscillating mass is constrained to vibrate in one direction only. When the vibration is changing direction, such devices are much less efficient. In this paper, a planar two degrees of freedom configuration is proposed where the natural frequency of the oscillator is independent of the direction of excitation. This potentially allows more efficient energy to be harvested in practical circumstances.