Performance evaluation of KHU Mark2 parallel multi-frequency EIT system

We describe a new parallel multi-frequency EIT system, KHU Mark2. It is based on the impedance measurement module (IMM), which comprises a single-ended constant current source and a voltmeter. Each IMM has an FPGA for its independent operations including current injection at multiple frequencies, vo...

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Bibliographic Details
Published in:Journal of physics. Conference series 2010-04, Vol.224 (1), p.012013
Main Authors: Kim, D Y, Wi, H, Yoo, P J, Oh, T I, Woo, E J
Format: Article
Language:English
Subjects:
Arbitration
Backplanes
Controllers
Current injection
Current sources
Custom design
Data exchange
Demodulation
Electric potential
Impedance measurement
Injection current
Intranets
Performance evaluation
Physics
Size reduction
Voltage
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Description
Summary:We describe a new parallel multi-frequency EIT system, KHU Mark2. It is based on the impedance measurement module (IMM), which comprises a single-ended constant current source and a voltmeter. Each IMM has an FPGA for its independent operations including current injection at multiple frequencies, voltage amplification, ADC, digital phase-sensitive demodulation and intra-networking with a main controller of the system. The main controller is based on a DSP and an isolated USB for its connection to a PC. There is an FPGA-based intranet controller, which arbitrates data exchanges between the DSP and multiple IMMs. Unlike its precursor, KHU Mark1, it is a true parallel system with no switching for both current injection and voltage sensing. The small size of the IMM results in a much reduced dimension of a multi-channel system. The KHU Mark2 can be assembled in any channels between 1 and 64. Depending on a chosen application, we custom design an analog backplane that interfaces multiple IMMs with electrodes. Special care was given to the system calibration to maximize its performance in frequency-difference EIT imaging as well as time-difference. Flexibility is the key improvement factor compared with the KHU Mark1. The new system can accommodate any current injection and voltage sensing protocol including the optimal injection current pattern. Reduced size and new internal architecture significantly improved mechanical as well as electrical stability of the system.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/224/1/012013