Feasibility Study of Joint Exoskeleton Device Without Bowden Cables Based on Highly Integrated Wireless Fluxgate Sensor

In order to monitor motor current in a finger exoskeleton device, a fully integrated fluxgate magnetometer with wireless connectivity has been developed. By using a fluxgate sensor and integrating a 2.4-GHz wireless transmission circuit, the finger movement can be more accurate and natural, while also reducing the weight and complexity of the exoskeleton design compared to the traditional Bowden cable transmission system. The proposed sensor chip is a high integration of fluxgate magnetometer featured with accuracy and sensitivity, it has a gain of 14.3 V/T, low noise density of 4.5 nT/ $\surd $ Hz @ 1 Hz for a CMOS technology sensor, and a measurement range of ±1.5 mT. With only a 1.5% gain variation and low nonlinearity from 0.01% to −0.1%, the sensor also has a wide dynamic magnetic field range from 1.5 to $- 1.5\,\,\mu \text{T}$ . Furthermore, this chip can transmit wireless data at a power level of −25 dBm and a range of up to 30 cm, making it easy to integrate with each joint of the exoskeleton device without requiring Bowden cable-based transmission.

I. Introduction

Stroke is a significant global health issue that results in high morbidity and mortality rates. For chronic stroke patients, recovering hand function is often a crucial aspect of their rehabilitation [1], [2]. Exoskeletons have emerged as a promising technology for hand rehabilitation, but traditional exoskeletons that use a Bowden cable transmission can be bulky and complicated [3], [4]. However, a fully integrated fluxgate magnetometer provides numerous advantages over conventional designs for monitoring motor current in a finger exoskeleton device.