Willemsen A T, Bloemhof F, Boom H B
Department of Electrical Engineering, University of Twente, Enschede, The Netherlands.
IEEE Trans Biomed Eng. 1990 Dec;37(12):1201-8. doi: 10.1109/10.64463.
The development of implantable peroneal nerve stimulators has increased interest in sensors which can detect the different phases of walking (stance and swing). Accelerometers, having a potential for implantation, are studied as detectors for the swing phase of walking to replace footswitches. Theoretically, we could show that accelerometers can be used to distinguish between stance and swing phase. Attaching accelerometers between ankle and knee joint the equivalent acceleration of the ankle joint was calculated. This resulted in a typical and reproducible signal in which the different walking phases were identified. Automatic detection algorithms, based on cross correlation calculation were developed and tested. Measurements from four healthy and four hemiplegic subjects resulted in a total of 317 and 272 steps, respectively. One of the hemiplegic subjects was considered to be a failure due to large disturbances in the acceleration signal during the swing phase of walking, which may be related to the use of crutches. Taking part of the data as a learning set and the other part as an evaluation set we found two errors in the push-off detection for both the healthy subjects and the remaining three hemiplegic subjects, out of 152 and 106 steps, respectively. In addition, we showed that when using one accelerometer closely below the knee joint almost identical results can be achieved. This could lead to a combination of sensor and stimulator into one implantable device.
植入式腓总神经刺激器的发展激发了人们对能够检测步行不同阶段（站立和摆动）的传感器的兴趣。具有植入潜力的加速度计作为步行摆动阶段的检测器进行研究，以替代脚踏开关。理论上，我们可以证明加速度计可用于区分站立和摆动阶段。将加速度计连接在踝关节和膝关节之间，计算踝关节的等效加速度。这产生了一个典型且可重复的信号，其中不同的步行阶段得以识别。基于互相关计算开发并测试了自动检测算法。来自四名健康受试者和四名偏瘫受试者的测量结果分别产生了总共317步和272步。其中一名偏瘫受试者由于步行摆动阶段加速度信号的较大干扰被视为失败，这可能与使用拐杖有关。将部分数据作为学习集，另一部分作为评估集，我们发现在健康受试者和其余三名偏瘫受试者的蹬离检测中分别有两个错误，健康受试者共152步，偏瘫受试者共106步。此外，我们表明，当在膝关节下方紧邻处使用一个加速度计时，可以获得几乎相同的结果。这可能会导致将传感器和刺激器组合成一个可植入设备。
