Collecting the energy generated by manual workers to monitor their working status and improve their working conditions by using a flexible rack mechanism

Abstract Currently, an increasing quantity of portable energy harvesting modules are being developed to capture the energy generated by human motion. However, the size and weight of a device can affect the smoothness and comfort of a user’s normal limb movements in the process of collecting energy generated by human movement. Especially on manual workers, this effect will significantly increase their physical exertion, so the design of energy-harvesting devices for wearing on manual workers has higher requirements. The bend knee energy harvester (BKEH) designed in the work presented in this paper used a laboratory-made flexible rack to harvest the energy generated by manual workers’ frequently bent knees during work. It converts the collected energy into electricity for various wearable devices to monitor the working status of manual workers and improve their working conditions. One end of the flexible rack is fixed to the upper thigh. When the user bends the knee, the flexible rack will move downward, causing the gear to rotate, thereby collecting the energy generated by the body’s movement. The BKEH was made of many lightweight materials and weighed only 406 g, greatly reducing the impact on the user’s normal limb movements and physical exertion. Practical experiments showed that the BKEH output open-circuit voltage is up to 80.3 V, the output power reached as high as 3.16 W, and the power density reached as high as 7.9 W kg −1 , which can effectively supply sufficient electrical power for wearable devices to work normally. The BKEH has a high practical value and good adaptability to human movement posture and can generate enough voltage and power to allow some wearable devices to work properly. These wearable devices can effectively provide users with the ability to monitor their work status and improve working conditions.