A Portable Plantar Pressure Distribution Measuring System Based On Embedded Soft-Core Processor

Plantar pressure distribution measuring system (PPDMS) which is helpful to the study of biomechanics is applied in the medical field and shoe-making industry. Currently, with the profound study of plantar pressure distribution in different motion status, those expensive and large plantar pressure distribution measuring systems with simple function could no longer meet the need of the applications. Therefore, present research mainly focuses on how to reduce the cost, improve the accuracy and develope new functions.In this paper, a portable plantar pressure distribution measuring system is introduced, which is based on embedded soft-core processor, and adopted the SOPC solution of SOC. With low cost of Cyclone II FPGA devices, the whole system is integrated into one chip, making it small, low power consumption, low cost. In the meantime, it helps enforce the ability of anti-jamming and improve the working speed, the precision, the reliability, and the expansibility. With subminiature pressure sensors embedded in the insole, not only the system can measure the pressure continuously to get precize plantar pressure data while people are walking or running, but also the insole size can be customized.According to the design requirement of PPDMS, the design scheme of the system is provided. Three modules of the system are described in this paper. Firstly, the hardware design and implement of data acquisition module is described. In this module, the distribution of plantar pressure can be acquired through multiple pressure microsensors embedded in an insole, and then converted into digital signals. Secondly, the hardware and software design and implement of control and data processing module is described. This module is the kernel of the system, implemented by the technology of embedded soft-core processor based on FPGA. It controls the whole system, processes and transmits the acquired data. Thirdly, the software design and implement of data display module is presented. This module aims to display the plantar pressure data clearly. On the whole, the system is implemented by the author of the paper on Altera FPGA platform. The experimental results show that the system can measure the plantar pressure distribution and display the data on-line or off-line correctly. The research is of great significance as it forms a solid technical basis for on-chip measuring and control system.