Kinematic analysis of an auto-winding system with the pawl-lever mechanism and its application in energy harvesting

It is known that human body contains rich chemical energy, part of which, up to 200 W, can be converted to mechanical energy when walking; thus, it is an ideal sustainable energy resource for portable electronic devices. The auto-winding system of mechanical watch movement is one of the most successful devices to harvest energy from human body motion. Invented some two hundred years ago, the auto-winding system is still being used today and evolving. In this paper, an auto-winding system with a pawl-lever mechanism, which is also known as Magic Lever mechanism, is studied in details. First, the kinematical model is developed, which consists of a double pendulum, a 4-bar mechanism and a reduction gear train. Next, simulation is conducted to evaluate its performance. Finally, based on this auto-winding system, a new device for energy harvesting is proposed. The new device will be capable of driving various portable electronic devices, such as mobile phone, MP3 and GPS receiver.