Path Loss Analysis and Transceiver Development for Human Body Communication-Based Signal Transmission for Wearable Robot Control

Wei Liao,Koki Muramatsu,Jianqing Wang

doi:10.1109/access.2021.3055261

Wei Liao, Koki Muramatsu + Show 1 more

Open Access

https://doi.org/10.1109/access.2021.3055261

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Abstract

Human body communication (HBC) technology is attracting a lot of attention for monitoring vital data and controlling wearable robot. In this paper, we focused on electroencephalogram (EEG) signal transmission from head to wrist in the 10–60 MHz HBC band. This is based on an idea to transmit an EEG signal to control a wearable robot. First, we clarified the basic transmission mechanism and characteristics using a highly simplified human body model. Next, we performed a detailed path loss analysis by finite difference time domain simulation using an anatomical human body model with various postures. Based on the analysis results, we identified the optimum transmitter position on the head and developed an impulse radio transceiver for verifying the feasibility of the technique. The results show that the developed transceiver can provide a data rate of 10 Mbps and the bit error rate can be kept below 10−3 for transmitting the EEG signals from the head to the wrist. Experimental validation with a bio-equivalent gel phantom also demonstrated high feasibility of transmitting the EEG signals along the human arm.

Highlights

In recent years, research on wireless devices based on human body communication (HBC) has become more and more extensive [1]–[3]
Since the signal is transmitted along the human body and the radiation generated outside the body is very small, HBC technology is attracting a lot of attention in health care and wearable robot control from the viewpoint of high reliability and high security [4]–[6]
When using this frequency band for wireless control of wearable robots, the transceiver should be designed based on the electrostatic coupling transmission mechanism, and the electrodes should be used to transmit and receive signals instead of antennas

Summary

INTRODUCTION

Research on wireless devices based on human body communication (HBC) has become more and more extensive [1]–[3]. Take more than 50% below 30 MHz and nearly 30% (equal to either the surface propagation component or the inductive component) up to 60 MHz within the total received electric field This means that the electrostatic coupling is the main transmission mechanism of HBC below 60 MHz. This means that the electrostatic coupling is the main transmission mechanism of HBC below 60 MHz When using this frequency band for wireless control of wearable robots, the transceiver should be designed based on the electrostatic coupling transmission mechanism, and the electrodes should be used to transmit and receive signals instead of antennas. The frequency-dependent permittivity and conductivity of various tissues in the human body were determined based on Gabriel’s measurement data [16] This simulation situation corresponds to that the EEG signals detected by the multiple sensors on the head are first collected by a coordinator placed at one position of the transmitting electrodes, and transmitted as a packetized signal to the receiver on the wrist by HBC technology.

COMMUNICATION PERFORMANCE EVALUATION

Findings

CONCLUSION