Self‐Powered Lower‐Limb Motion Detection with a Piezo‐Electromagnetic Generator

Human limbs generate a lot of energy during movement. To harvest energy during human lower‐limb movement and detect the human body's movement status, a piezo‐electromagnetic collaboration power generator is proposed. It consists of a piezoelectric energy unit and an electromagnetic energy unit. The electromagnetic unit is used for energy harvesting, while the piezoelectric unit is used for self‐powered and self‐sensing detection of lower‐limb movement. The operating principle of the generator is presented, and the theoretical model of the output characteristics is established and simulated. An experimental test platform is built, the detection of self‐powered lower limb movement is accomplished. Results show that the maximum output powers of the electromagnetic and piezoelectric energy units are 14.63 mW and 2.13 mW, respectively. The proposed energy harvester is capable of lighting up 104 Light Emitting Diodes (LEDs) and provides the power supply to a Thermo‐hygrometer. What's more, the self‐powered self‐sensing detection system can realize the detection of the swing frequency of the lower limb and deduce the relationship between the movement speed and the swing frequency, with a detection error of 0.82% for different individuals.