Application of a chatic stimulation to development of a chair free from backache

飞机、铁路和汽车等交通工具用于长途运输。在运输过程中，乘客被要求保持收紧的姿势，特别是在飞机上。因此，乘客会受到身体肌肉的痛苦压力的影响。人体内的身体压力有时会对健康造成严重危害。为了缓解肌肉的压力，最近推出了一种带有指压疗法的松弛机。在治疗中，身体可以得到一种放松的状态，被拳头敲打。本研究提供了周期性和混沌敲击刺激下人体生物信号的分析结果。人体皮肤上的电信号被测量。从身体的胸部检测到心电(Ecg)。肌电(EMG)的信号是从双臂的肌肉测量的。计算了被测信号的最大Lyapunov指数。利用Karhuen-Love变换(主成分分析)，阐明了在外界刺激下对人体信号的贡献。发现：1.当对身体施加快速周期性敲击时，心脏搏动增加到更高的频率。当人体被敲击机快速敲击时，肌电的最大Lyapunov指数比缓慢敲击和安静状态下的最大Lyapunov指数降低到更低的值。对肌电有贡献的物理参数个数减少。结果表明，人体受到的快速激振力会产生自由度较低的稳态周期响应。在安静状态、周期敲击和混沌激励三种测试条件下，心电信号表现出比肌电响应更复杂的非平稳行为。本实验测试发现，对人体的舒适刺激是一种混沌刺激。

Vehicles such as airplane, railway and automobile are used for a long distance transportation. During the transportation, passenger is enforced to have a tightened posture especially in the airplane. Therefore, passenger will be affected to a painful stress in muscles of the body. Physical stress in the human body sometimes will happen to be serious hazard to health. To release the stress on the muscle, recently, relaxation machine is introduced with facility of a finger pressure therapy. In the therapy, the body can get a relaxed condition knocked by a fist.This study presents the results of biological signal analysis in human body subjected to periodic and chaotic knocked-stimulation. Electrical signals on a skin of the body are measured. An electricalcardiogram(ECG) is detected from a chest of the body. The signal of an electromyogram (EMG) is measured from muscles of both arms. The maximum Lyapunov exponent is calculated for the signal under test. Using the Karhuen-Loeve transformation (Principal Component Analysis), contributions to the signal of the body under the external stimulation are clarified.It is found that the followings ;1. When the quick periodic knocking is applied to the body, cardiac beat of the heart increases to higher frequency.2. When the body is stricken quickly by the knocking machine, the maximum Lyapunov exponent of the EMG decreases to lower value compared to those of slow knocking condition and the quiet condition. The number of physical parameter contributed to the EMG decreases. It shows that the quick stimulated forces to the body will produce a steady-state periodic response with lower degree of freedom.3. Under three testings of quiet condition, periodic knocking and chaotic excitation, the signals of the ECG show more complex unsteady behavior than that of the responses of EMG.4. Comfortable excitation to the body is found to be the chaotic stimulation by the test in our experiment.