Shanghai Key Laboratory of Intelligent Manufacturing and Robotics, School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China.
Sensors (Basel). 2021 May 29;21(11):3780. doi: 10.3390/s21113780.
Accurately perceiving and predicting the parameters related to human walking is very important for man-machine coupled cooperative control systems such as exoskeletons and power prostheses. Plantar pressure data is rich in human gait and posture information and is an essential source of reference information as the input of the exoskeleton control system. Therefore, the proper design of the pressure sensing insole and validation is a big challenge considering the requirements such as convenience, reliability, no interference and so on. In this research, we developed a low-cost modular sensing unit based on the principle of photoelectric sensing and designed a plantar pressure sensing insole to achieve the purpose of sensing human walking gait and posture information. On the one hand, the sensor unit is made of economy-friendly commercial flexible circuits and elastic silicone, and the mechanical and electrical characteristics of the modular sensor unit are evaluated by a self-developed pressure-related calibration system. The calibration results show that the modular sensor based on the photoelectric sensing principle has fast response and negligible hysteresis. On the other hand, we analyzed the area where the plantar pressure is densely distributed. One benefit of the modular sensing unit design is that it is rather convenient to fabricate different insole solutions, so we fabricated and compared several pressure-sensitive insole solutions in this preliminary study. During the dynamic locomotion experiments of wearing the pressure-sensing insole, the time series signal of each sensor unit was collected and analyzed. The results show that the pressure sensing insole based on the photoelectric effect can sense the distribution of the plantar pressure by capturing the deformation of the insole caused by the foot contact during locomotion, and provide reliable gait information for wearable applications.
准确感知和预测与人类行走相关的参数对于人机耦合协作控制系统（如外骨骼和动力假肢）非常重要。足底压力数据包含丰富的人类步态和姿势信息，是外骨骼控制系统输入的重要参考信息源。因此，考虑到便利性、可靠性、无干扰等要求，适当设计压力感应鞋垫并进行验证是一个巨大的挑战。在这项研究中，我们基于光电感应原理开发了一种低成本的模块化传感单元，并设计了一种足底压力感应鞋垫，以实现感知人类行走步态和姿势信息的目的。一方面，传感器单元由经济实惠的商用柔性电路和弹性硅树脂制成，并通过自主开发的压力相关校准系统评估模块化传感器单元的机械和电气特性。校准结果表明，基于光电感应原理的模块化传感器具有快速响应和可忽略的滞后。另一方面，我们分析了足底压力密集分布的区域。模块化传感单元设计的一个好处是，它非常方便制造不同的鞋垫解决方案，因此我们在这项初步研究中制造并比较了几种压力敏感鞋垫解决方案。在穿着压力感应鞋垫进行动态运动实验期间，收集和分析了每个传感器单元的时间序列信号。结果表明，基于光电效应的压力感应鞋垫可以通过捕捉运动过程中脚接触引起的鞋垫变形来感知足底压力的分布，并为可穿戴应用提供可靠的步态信息。
