Dynamic Measurement of Legs Motion in Sagittal Plane Based on Soft Wearable Sensors

Yaqing Feng,David Mccoul,Jianwen Zhao,Bo Huang,Tao Jin,Shihao Qin,Yongze Li

doi:10.1155/2020/9231571

Abstract

Human motion capture is widely used in exoskeleton robots, human-computer interaction, sports analysis, rehabilitation training, and many other fields. However, soft-sensor-based wearable dynamic measurement has not been well achieved. In this paper, the dynamic measurements of legs were investigated by using dielectric elastomers as stain sensors, and an alternating signal was applied to detect the dynamic rotational angles of the legs. To realize a quick response, parameters of the sensors were optimized by circuit analysis. The sensor can detect hip, knee, and ankle joint motions with a sample frequency of 200 Hz. The measurements of the sensors were compared with a commercial motion capture system from PhaseSpace, and dynamic errors between them were smaller than 3° when squatting and walking at low speed and smaller than 5° when walking at high speed. Experiments therefore demonstrate the feasibility of the integrated wearable stretch sensors with pants.

Highlights

Motion capture systems for tracking leg motion are widely applied in many fields, such as rehabilitation [1,2,3], competitive training [4], human-computer interaction [5], movie, animation [6], and exoskeleton assist systems [7]
The current measurement methods mainly include optical dynamic motion capture system based on vision technology [13], ultrasound based [14], electromagnetic based [15], linkage measurement based on mechanism, and IMUs [16, 17]
The first three methods require a system to generate a specialized peripheral signal, and the system cannot be fully integrated into the human body, so the first three methods are not applicable to measure the joint motions of mobile human body

Summary

Introduction

Motion capture systems for tracking leg motion are widely applied in many fields, such as rehabilitation [1,2,3], competitive training [4], human-computer interaction [5], movie, animation [6], and exoskeleton assist systems [7]. Swimming requires proper leg posture to obtain optimal performance, and accurate feedback of leg motion can guide training for the sport [12]. The inertial sensor obtains the angle value through integral operations, which can cause a large drifting. Soft strain sensor is a good candidate to measure the motion of human joint, because of its flexibility, comfort, compliance, low cost, and large strain

Methods

Findings

Discussion

Conclusion