融合足底运动能采集器与IMU的步态监测系统设计与实验

Design and Experiment of Gait Monitoring System Integrating Plantar Kinetic Energy Harvester and IMU

摘要: 针对传统步态分析设备存在成本高昂、续航能力弱、不适用于长期贴身佩戴的问题，本文设计并实现了一套融合PVDF压电薄膜足底运动能采集器与JY61P惯性测量单元(IMU)的步态监测系统。系统在足跟、中足、前掌三个位置布置了三路悬臂梁式PVDF压电采集单元，用于采集足底动态力电信号；通过电荷放大、偏置匹配与低通滤波电路完成信号调理。系统以STM32F407单片机为主控核心，实现多源数据同步采集、时间戳标记与数据帧封装，并借助ESP8266无线模块完成数据的WiFi传输。上位机可实现信号波形实时显示、数据存储、步频计算及基于滑动窗口的步态识别。实验结果表明，PVDF压电采集单元可有效识别足跟着地、支撑过渡、前掌蹬离等典型步态事件，IMU信号可补充足部姿态与空间运动特征。双信号融合特征的步态识别平均准确率达95.51%；步频检测平均准确率为98.3%，整体性能优于单一传感器方案。该研究可为低功耗、自供能可穿戴步态监测设备的研发提供一定的技术参考。

Abstract: Aiming at the drawbacks of traditional gait analysis equipment, including high cost, short battery life and poor adaptability to long-term close-fitting wear, this paper proposes a gait monitoring system combining a plantar kinetic energy harvester based on PVDF piezoelectric thin films and JY61P inertial measurement unit (IMU). Three cantilever-beam PVDF acquisition units are arranged at the heel, midfoot and forefoot to collect dynamic piezoelectric signals from the plantar region. Signal conditioning is realized through charge amplification, bias matching and low-pass filter circuits. Taking the STM32F407 microcontroller as the main control core, the system realizes synchronous multi-source data acquisition, timestamp marking and data frame encapsulation, and completes Wi-Fi data transmission via the ESP8266 wireless module. The upper computer supports real-time signal waveform display, data storage, cadence calculation and sliding window-based gait recognition. Experimental results show that the PVDF acquisition units can effectively identify typical gait events such as heel strike, stance transition and forefoot push-off, while IMU signals provide supplementary information on foot posture and spatial motion characteristics. The average accuracy of gait recognition based on dual-signal fused features reaches 95.51%, and the average accuracy of cadence detection is 98.3%. The overall performance outperforms schemes using a single sensor. This research provides technical references for the development of low-power, self-powered wearable gait monitoring devices.