以個人數位助理為基礎之腳底壓力量測系統設計

The Development of A PDA-based Plantar Pressures Acquisition System

王志元(Chih-Yuan Wang)

指導教授 ： 胡威志

中原大學/工學院/醫學工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200512

摘要

在醫學及生物力學的應用上，腳底壓力的分佈是個辨別疾病的重要特徵；人類的步態會因為個體特性的差異而有所不同，醫師便可藉由步態的生理訊號分析以瞭解發病的原因，並診斷患者的狀況。大多數的步態研究，都是由醫院或專業的步態分析研究室應用市面上的腳底壓力量測系統商品，來分析腳底壓力與病症間的關係；但系統價格過於昂貴，並無法普遍地讓一般大眾擁有及使用。另外，在參考文獻上所提及的腳底壓力量測系統，其壓力點的解析度都過低，每腳僅量測7或12個壓力點，並無法完整地監測腳底壓力資料。在成本及高解析度的考量下，採用越來越普及的個人數位助理以及高解析度的腳壓墊來建立此系統。
因此，本論文的主要目的，在於建立一套以個人數位助理為基礎的腳底壓力量測系統。本系統使用TrgPro Palm Pilot當作系統的控制以及儲存單元，此個人數位助理的CPU時脈速度為20MHz，透過其內建的CompactFlash介面輸出控制碼，驅控CF_8255 IO卡對擷取電路進行控制及訊號擷取的動作；擷取電路是使用多工器、放大器以及類比/數位轉換電路來建構，透過多工器選擇所要量測的腳底壓力點，此壓力點的足底壓力資料便經腳壓墊換能器轉換為電阻值，再經過放大器、類比/數位轉換電路的處理而成為數位訊號，最後讀回個人數位助理內儲存。
本論文的研究成果，建立了可攜式、低成本、高解析度的腳底壓力量測系統：(1)以電池供應系統電源，配合個人數位助理小巧的特性，可以克服地形上的限制；(2)採用Tekscan Inc.的腳壓墊換能器，其解析度最高為每腳960個壓力點，配合並列埠進行大量的資料傳輸，建立高解析度的機制；(3)扣除了個人數位助理以及軟體的費用，可建立低成本的腳底壓力量測系統。此外，本系統的擷取速度可達到每秒11,520個壓力點數值的量測。研究的結果顯示，以個人數位助理為基礎，來建立一可攜式的生理訊號擷取裝置是可行的方式；利用個人數位助理本身的輕便、可攜、實用等特性，以及其並列埠介面，再加上低成本建立的硬體電路，便可發展出經濟實用的可攜式生理訊號擷取裝置，讓大多數的人都可以容易地擁有及使用。

關鍵字

並列埠 ； 個人數位助理 ； 步態分析 ； 高解析度 ； 可攜式 ； 腳底壓力

並列摘要

The distribution of plantar pressure is an important characteristic to identify diseases such as peripheral neuropathy, plantar ulcer, varus, talipes valgus, flat-footed, etc. Patients with polyneuropathy often lose sensation of pain at their feet. They are high-risk groups for developing neuropathic ulcers on the plantar surface of their feet. That may lead to lower extremity amputation. Using plantar pressure evaluation system, physicians are able to monitor the improvement of patient’s illness. Furthermore, most researchers in gait study utilize the plantar pressures acquisition systems to identify the relationship between plantar pressures and diseases. These commercial plantar pressures acquisition are expensive. In addition, the existing plantar pressures acquisition systems also have the problem of low resolution. These systems only can detect 7 or 12 pressure points at one foot.
Considering the cost and the resolution, the purpose of this research is to develop a PDA-based plantar pressures acquisition system. The designed system utilizes the TrgPro Palm PilotTM as the unit of controlling system and storing data. The device operates at a crystal clock frequency of 20MHz. The CompactFlashTM interface of PDA is utilized to output control code and acquire data. The plantar pressure sensor insole has 960 independent pressure points. The applied pressure to the sensor of insole decreases its resistance, which causes the output voltage of the amplifier circuit to increase. A set of multiplexer is used to activate the selected pressure point at insole for acquisition. The PDA acquires digital voltage data from the A/D converter and stores the data into database. A software program that will evaluate the serial gait patterns with distribution and magnitudes of plantar pressure. The program also calculates the parameters for gait analysis, such as gait cycle, peak value of pressure, center of pressure, etc.
In summary, this thesis has developed a portable, low-cost and high-resolution plantar pressures acquisition system. This system utilizes batteries for power supply. And, the system also utilizes the characteristics of lightweight PDA as a portable system. The design takes advantage of CompactFlashTM interface as parallel port for transporting a large quantity of data to establish the characteristic of temporal high resolution. As well as high spatial resolution, the sampling rate of a pressure point is 11,520Hz. The future development should be focused on improving the sampling rate of a pressure point, reducing the size of acquisition system and the weight of batteries. Then, the designed PDA-based plantar pressures acquisition system can be commercialized and meet the clinical requirement to aid patients and the general of people.

並列關鍵字

parallel port ； high-resolution ； PDA ； portable ； plantar pressure ； gait analysis

參考文獻

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