The Design And Implement Of A Multi-channel Plantar Pressure Measurement System

As the sports medicine and rehabilitation medicine developed rapidly, more and more people begin to know the importance of foot. Since then, there has been growing interest in the relationship between foot and movement function diseases. It has been found that different places of the plantar have different pressure, people who get movement function diseases have different plantar pressure from that who do not get. To research the changing regularity of the pressure, we may find some lesions or dyskinesia of the feet. This paper presents a multi-channel data acquisition system, which is based on ultra-low-power MSP430 microcontroller and nRF24L01 wireless communication.With the purpose of detecting plantar pressure more easily and more reliable, the right pressure sensor should be chosen. Therefore, the performance about the PVDF piezoelectric-film sensor and its advantages are discussed in the first step of this paper. Moreover, the reasonable preamplifier stage circuit is designed, too. It turns out that the PVDF piezoelectric-film sensor is suitable for the measurement. As the system requirements, the hardware structure scheme of the whole system is divided into two parts: one part is the main system; the other part is the sub system. The sub system is mainly used for data acquisition; it consists of a MSP430 Micro Control Unit (MCU), eight PVDF piezoelectric film sensors, eight charge amplifiers, eight low pass filter circuits, a multiplexer, a voltage adjustment circuit and an nRF24L01 wireless module. Well, the main system has two functions: one is communicating with the sub system by wireless communication module; another is transmitting data to PC by serial port. It contains a MCU, a TTL to RS232 level change circuit and an nRF24L01 wireless module. In this paper, all the circuits are shown in details. Besides, the multiplexer and A/D control, data acquisition, data wireless transmission and serial port communication are realized by the MCU software. The interfaces, which are used for real-time displaying data in kinds of styles, are designed by the LabVIEW. They had realized the functions such as: waveform display, intensity graph display, data storage, waveform playback and some simple data analysis. After the hardware and software designs finished, system debugs have being done, in order to make the system much more perfect. In the end, scientific experiment is utilized to test and verify the system that weather it is feasible and reliable.With this system, we can easily acquire and record the plantar pressure, some potential movement function diseases analysis and diagnosis based on those data can be done as well. It can also be used to monitor improvements in rehabilitation. This system has a positive significance in clinical application and important actual meanings.