Robotic Skin Thermal Sensing Using Electrical Impedance Tomography

  • Ahmed Abdulsalam Ahmed

Student thesis: Master's Thesis

Abstract

Electrical Impedance Tomography (EIT) is a non-invasive, non-ionizing imaging technique that incorporates the internal conductivity changes to provide the spatial mapping of a region under test. Using current excitation, it is possible to determine the internal conductivity distribution of electrically conductive body that responds to pressure stimuli with local changes in conductivity. It allows for hardware that is low cost, scalable and health-safe; making it ideal for continues monitoring purposes such as for artificial skin. The motivation to create better tactile sensors that have better skin-like properties has led to exploration of EIT-based tactile sensor, where a skin like material that is thin, flexible and stretchable is able to responds to the applied force with changes in internal conductivity. However, the utilization of such skin for thermal sensing applications is novel and has not been explored. Traditionally, EIT systems are bulky, power intensive, and require longer electrode to hardware connections; affecting measurements accuracy and degrading the high frequency operation due to the increased noise and parasitics. Incorporating a Field Programmable Gate Array (FPGA) to a State-of-the-art EIT systems allows for a portable and low power system that achieves the required SNR necessary for robotic applications. Cyclone-V FPGA-based, 16 electrode EIT hardware system is designed with a custom MATLAB software for system control and communication. Temperature experiments were conducted using the designed EIT system where a flexible EIT sensor was fixed over a sheet of Perspex glass to eliminate the pressure effect on conductivity changes. Measurements were made with an aluminum cup where it was in contact with the EIT sensor at different temperatures (20.2C and 65.4C) while taking continuous voltage measurements. The experiment showed that, when it was in contact with 65.4C aluminum cup, the EIT voltage measurements increase by more than 20mV and the reconstructed EIT images showed great locality. In addition, the EIT system did not respond to the room temperature stimuli.
Date of AwardMay 2021
Original languageAmerican English

Keywords

  • EIT
  • Temperature
  • Robotic Skin
  • FPGA
  • Demodulator.

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