Self-powered Triboelectric Joint Sensors And Their Application For Joint Motion Monitoring

Triboelectric have the characteristics of simple structure,low cost and high environmental adaptability in sensing and energy harvesting.Based on the principle that dielectric materials generate electrical signals through contact or friction,they have good advantages for application in some special scenarios.There are a large number of posture detection sensors in human joint assistive devices that need to be on standby for a long time to detect gait and thus provide guidance for assistive strategies.This thesis investigates the preliminary application of triboelectric sensors to joint assist devices and gait analysis by characterizing the parameters related to rotational motion.In this thesis,I first designed a triboelectric sensor for powering and detecting gait by taking advantage of the high degree of freedom of the triboelectric sensor,and conducted comparative experiments on the material properties and structural design of the sensor to ensure the output performance of the sensor.Secondly,the hardware aspect of this thesis designed the mechanical structure of the whole set of hip-assist device through this sensor;the STM32F103RBT6 was used as MCU to design the main control system of this device for collecting and processing the sensor signal and controlling the DC motor to apply the assist.For the software aspect this thesis realizes the acquisition of the tiny signal of the triboelectric in the working environment of the high-power motor;by improving the control algorithm,the control response of the booster system is improved;this thesis also designs a neural network to build a dataset training model for the four gait signals collected by this sensor and achieves more than 90% accuracy in the classification of all four gait states.Finally,this thesis validates the designed triboelectric sensor for systematic application.With the control system designed in this thesis,the booster device still has a delay of 100～400ms.When the wearer’s gait speed is fast,it has a certain impact on the wearer’s normal gait,while the slower gait speed is able to provide a suitable booster effect.This limitation mainly comes from the fact that the robustness of the single sensor data source cannot meet the system requirements.In the gait classification application,experiments were conducted on wearers with different body parameters to verify the value of the sensor in gait classification,with an average recognition rate of over 90%.The triboelectric sensor designed in this thesis is experimentally capable of monitoring parameters related to rotational motion.Moreover,the hip joint assist device designed based on this sensor was experimented in both assist control and gait classification,and the experimental results have verified its potential in the field of joint assist to a certain extent.