Development Of A Simulating Human Respiration System For Non-contact Life Detection

Life detection based on radar is a frontier non-contact detecting technology which combines radar theory with biomedical engineering. It makes use of electromagnetic wave as medium, which can penetrate the nonmetal materials such as clothes, brick walls, ruins, etc. As a result, this technology can detect human physical motions caused by respiration and heartbeat without any electrodes or sensors, then picks up the vital signs of human and identifies whether there is a person or not. This technology has a very important and practical value, which can be widely applied to military medicine, emergency rescue, counter-terror field and so on.The experiment of non-contact life detection based on radar requires the vital signal of the target stable and quantitative. And we often use human as the detecting target during experiments. However, the physical state and body gesture of each person are different. Even the same person, his vital signals are also diverse at different periods of time. These factors affect not only the objective evaluation and the quantitative detection of radar systems, but also the scientific and in-depth study of the life detecting technology. Besides, some experiments require different persons as detecting targets who are different in reflecting the electromagnetic wave. Once the experiment takes a long time, it will cause a waste of human resources and time. Moreover, when the experiment is carried out in dangerous environment such as in ruins or under rubbles, it is inadvisable to use human as the detecting target. For these reasons, it is imperative to develop a human respiration simulator. So the simulating human respiration system developed in this thesis not only overcomes the problems which are caused by human detecting target, but also simulates the respiration of different persons steadily, quantitatively and adjustably. It provides a calibration signal for the non-contact life detection.This thesis focuses on the following aspects:1. According to the requirement of target in non-contact life detection experiment and the characteristic of human respiration, the simulating human respiration system has been developed, which consists of a CPR model, a BIPAP respirator, a special ballonet and a sheet metal.2. The experiments respectively using human and the system as the detecting target have been carried out. By contrast, it is concluded that respiration of the system is much more stable than human's. And the range of the human reflecting energy of electromagnetic wave has been statistically calculated. In the life detecting experiments the system can simulate the range by adjust it parameters.3. The circuit of displacement sensor has been designed for the system to monitor the displacement of chest during the respiration. And the power supply circuit of the system also has been designed. So the system can work as usual without the mains supply. Innovations in this thesis are listed as follows:1. The system can simulate human respiration steadily and quantitatively by means of air drive. Its frequency, amplitude and ratio of the time of inspiration to expiration are adjustable.2. The system and human are alike in appearance. During the experiments in confined space or dangerous environment, it can take the place of human and act as detecting target with multi-posture.