A distributed data acquisition architecture for magnetic positioning systems

We illustrate a devised and implemented data acquisition system (DAQ) for a magnetic positioning system (MPS) that is currently under development. This system aims to track position and attitude of an active transmitting coil (TX) supplied with a sinusoidal current, whose generated magnetic field induces tensions on an array of passive receiving coils (RX). The DAQ system has to acquire voltages at all RX coils. These signals are then processed to estimate the TX coordinates, according to a mathematical model in order. In order to track the TX in real-time with a good resolution, voltages have to be measured simultaneously on all RXs. To this aim, we opted for a distributed architecture of microcontroller units (MCU). Each selected MCU has four analog-to-digital converters (ADC) that can work in parallel. Moreover multiple MCUs can be triggered simultaneously by a single MCU in a master-slave configuration. We used MCUs with a fast dual-core CPU. Each unit can directly process its own acquired signals. Then all data are sent to the master MCU, which estimates the coordinates of the TX. According to a preliminary analisys, this tracking system should achieve more than fifty coordinates measurements per second.