An Accurate Wearable Foot Clearance Estimation System: Toward a Real-Time Measurement System

Abstract

Abstract-This work presents an accurate, robust, wearable measurement system for foot clearance estimation along with algorithms to provide a real-time estimate of foot height and orientation. Different configurations of infrared distance meter sensors were used, both alone and in combination with an inertial measurement unit. In order to accurately estimate the foot clearance when in presence of daylight and when the foot orientation changes dynamically during walking, several algorithms were designed based on physics of sensors and tuned using the acquired data against a reference system. These algorithms, specific to the number of sensors, include the estimators of the foot orientation and estimators of the foot clearance. These estimators are tested on normal walking (RMS error ≤ 8.4mm) and walking with exaggerated step heights and inversion-eversion rotations. A Bayesian fusion of estimators was also implemented to better cope with the extreme and abnormal walking kinematics while maintaining a high performance for normal walking. All estimators were trained on uniformly distributed bootstrapped sub-samples of data and tested on several normal and abnormal walking data. The results proved the robustness of the proposed system against variations in the gait kinematics (|mean| ± standard deviation of error for heel and toe clearance was equal to or smaller than 3.1±9.3 mm when using a Bayesian fusion of three different estimators) and environment lighting (with an introduced error of 1 to 4% of actual distance).Index Terms-Foot clearance, infrared range meter, inertial measurement unit, Bayesian fusion.

The Effect of Treadmill Walking on Gait and Upper Trunk through Linear and Nonlinear Analysis Methods

“…Dadashi et al [18] found that foot clearance could characterize the risky gait pattern through analyzing the dataset from 1400 participants. Arami et al [19] designed an accurate wearable foot clearance estimation system with infrared distance meter sensors and inertial measurement unit to provide a real-time estimation of foot height and orientation. Several related studies about gait analysis are presented in Table 1.…”

Static and Dynamic Accuracy of an Innovative Miniaturized Wearable Platform for Short Range Distance Measurements for Human Movement Applications

“…However, this technology does not allow for direct measurements of the relative position of body segments such as the feet, which are necessary to estimate the base of support or step width variation over time [ 15 ]. Some researchers have combined inertial measurement unit (IMU) with ultrasounds (US), light intensity infrared (IR-LI) and Video camera (VC) sensors [ 16 , 17 , 18 , 19 ]. US sensors estimate a distance by measuring the time required by an ultrasonic wave to travel from the transmitter to the receiver [ 16 , 20 ].…”

“…US sensors estimate a distance by measuring the time required by an ultrasonic wave to travel from the transmitter to the receiver [ 16 , 20 ]. IR-LI sensors determine the distance by measuring the amount of light reflected from an object [ 17 , 18 , 21 ]. VCs have been used to measure the distance from a matrix of infrared LEDs positioned in front of it [ 19 , 22 ].…”

“…Few previous studies have proposed to integrate IMU data with distance measurements, based on the abovementioned technologies, for analyzing human gait. Arami et al [ 17 ] presented a wearable system for the estimation of the foot clearance during gait. Different system configurations, from one to three IR-LI sensors, were investigated on a single healthy subject.…”

Quantitative Modeling of Spasticity for Clinical Assessment, Treatment and Rehabilitation

“…Estimation of joint axis and angle estimation using IMU measurements has been shown to be accurate and valid when compared to camera-based motion capture systems [ 53 , 54 ], or compared to magnetic tracking systems [ 55 ]. IMU-based measurement of human kinematics has also been demonstrated with high repeatability and validity, for instance in gait analysis [ 56 , 57 ], and when fused with other sensors [ 58 ], and in 3D joint angle estimation [ 55 ]. Even using a single IMU has been shown to result in accurate motion analysis in studies evaluating rehabilitation exercise performance [ 59 , 60 ].…”