A Shoe With Bipolar Electrodes for Ground Impedance-Based Pedestrian Pathway Classification

Basic activities like walking and standing involve foot-eye coordination. Due to the lack of proper foot-eye coordination in visually impaired, diabetic people with mono-filament issues, and lower leg amputees, it becomes challenging for them to walk or stand, which leads to mobility issues. An external feedback mechanism for classifying the type of pedestrian pathways while walking or standing can significantly improve this problem. Researchers have reported techniques involving cameras, inertial measurement units, audio, vibration, and ultrasonic-based signals. Still, all these techniques provide information based on the surface/texture properties of pathways. This data can give erroneous outputs due to the lack of information below the ground surface. In our earlier works, a technique was developed to measure the electrical impedance of the ground between the legs of the person to classify pedestrian pathways. It involves passing the current through the body and is subjective to the person’s stride length. To resolve these limitations, a novel method to measure the ground impedance under only one shoe is proposed in this article. This method uses bipolar electrodes to stop the leakage current from the body as the current from the sensor leg to the other leg becomes zero. A finite element analysis (FEA) is performed to show the usefulness of the bipolar electrodes over unipolar electrodes. An error analysis, laboratory, and field testing are performed on the developed prototype to see the system’s practicality. The measurements from the prototype system are verified using the Four Probe Test and analytical model based on conformal mapping.