A Single-Camera Computer Vision-Based Method for 3D L5/S1 MomentEstimation During Lifting Tasks

2021 ◽  
Vol 65 (1) ◽  
pp. 472-476
Author(s):  
Hanwen Wang ◽  
Ziyang Xie ◽  
Lu Lu ◽  
Li Li ◽  
Xu Xu ◽  
...  
Keyword(s):  
Computer Vision ◽  
Motion Tracking ◽  
Material Handling ◽  
Tracking System ◽  
Joint Moment ◽  
Low Back ◽  
Joint Loading ◽  
Reconstruction Methods ◽  
Comparison Results ◽  
Motion Tracking System

Excessive low back joint loading during material handling tasks is considered a critical risk factor of musculoskeletal disorders (MSD). Therefore, it is necessary to understand the low-back joint loading during manual material handling to prevent low-back injuries. Recently, computer vision-based pose reconstruction methods have shown the potential in human kinematics and kinetics analysis. This study performed L5/S1 joint moment estimation by combining VideoPose3D, an open-source pose reconstruction library, and a biomechanical model. Twelve participants lifting a 10 kg plastic crate from the floor to a knuckle-height shelf were captured by a camera and a laboratory-based motion tracking system. The L5/S1 joint moments obtained from the camera video were compared with those obtained from the motion tracking system. The comparison results indicate that estimated total peak L5/S1 moments during lifting tasks were positively correlated to the reference L5/S1 joint moment, and the percentage error is 7.7%.

Estimating 3-D L5/S1 Moments During Manual Lifting Using a Video Coding System

2012 ◽  
Vol 54 (6) ◽  
pp. 1053-1065 ◽  
Author(s):  
Xu Xu ◽  
Chien-Chi Chang ◽  
Gert S. Faber ◽  
Idsart Kingma ◽  
Jack T. Dennerlein
Keyword(s):  
Video Coding ◽  
Interrater Reliability ◽  
Motion Tracking ◽  
Tracking System ◽  
Intraclass Correlation ◽  
Coding System ◽  
Joint Loading ◽  
Joint Moments ◽  
Video Clips ◽  
Motion Tracking System

Objective: The aim of the study was to investigate the validity and interrater reliability of using a proposed video coding system to estimate the dynamical 3-D L5/S1 joint moment on the basis of four key frames from video clips of asymmetric lifting tasks. Background: L5/S1 joint loading has been widely adopted to quantify low-back loading during lifting tasks. However, the measurement of L5/S1 joint loading usually requires a laboratory environment, which cannot be applied during field surveys. Method: The validity of this system was investigated by comparing the estimated L5/S1 joint moments of various simulated lifting tasks with motion tracking system-based reference L5/S1 joint moments. Results: The comparison showed that the video coding system yielded good estimates on peak moment ( r = .91, average absolute error [AAE] = 20.3 Nm) and cumulative moment ( r = .88, AAE = 22.5 Nm·sec) of the sagittal plane. The interrater reliability of this system was assessed among 10 raters who used this system. The intraclass correlation ranged between .51 and .89 for the moments of different planes. Conclusion: The results of the validity and interrater reliability analyses showed that the proposed video coding system could provide a good estimate of total L5/S1 joint loading on the basis of side-view video clips of the simulated lifting tasks. Application: Although it was not as accurate as a motion tracking system for L5/S1 joint loading calculations, this approach can be an alternative for back load estimation for some lifting configurations when the use of motion tracking systems is not possible.

scholarly journals Desktop lighting for comfortable use of a computer screen

Work ◽  
2021 ◽  
Vol 68 (s1) ◽  
pp. S209-S221
Author(s):  
Lu Han ◽  
Hechen Zhang ◽  
Zhongxia Xiang ◽  
Jinze Shang ◽  
Shabila Anjani ◽  
...  
Keyword(s):  
High Intensity ◽  
Motion Tracking ◽  
Tracking System ◽  
Computer User ◽  
Eye Tracker ◽  
Computer Screen ◽  
Task Load ◽  
Trunk Movements ◽  
Motion Tracking System ◽  
Nasa Task Load Index

BACKGROUND: The contrast between a bright computer screen and a dark ambient environment may influence comfort of the users, especially on their eyes. OBJECTIVE: The objective of this research is to identify the optimal desktop lighting for the comfortable use of the computer screen in a dark environment. METHODS: An experiment was designed where seven illumination setups were introduced for the users to perform their leisure tasks on a computer screen. Fifteen healthy subjects participated in the experiments. During each session, durations of the eye blinks, fixations and saccades of the user were recorded by an eye tracker. His/her neck and trunk movements were recorded by a motion tracking system as well. The comfort/discomfort questionnaire, localized postural discomfort questionnaire, NASA task load index and computer user questionnaire were used to record the overall comfort/discomfort, the local perceived physical discomfort, the cognitive workload, and general/eye health problems, respectively. RESULTS: Subjective and objective measurement results indicated that users felt more comfortable with high intensity warm lights using a computer screen. We also identified that the eye fixation durations, as well as the scores of two questions in the computer user questionnaire, have significant negative correlations with comfort. On the other side, the durations of blinks and the scores of three questions in the computer user questionnaire, were significantly correlated with discomfort. CONCLUSION: The warm (3000K) and high intensity (1500 lux) light reduced the visual and cognitive fatigue of the user and therefore improve the comfort of the user during the use of a computer screen.

scholarly journals Multi-sensor three-dimensional Monte Carlo localization for long-term aerial robot navigation

2017 ◽  
Vol 14 (5) ◽  
pp. 172988141773275 ◽  
Author(s):  
Francisco J Perez-Grau ◽  
Fernando Caballero ◽  
Antidio Viguria ◽  
Anibal Ollero
Keyword(s):  
Monte Carlo ◽  
Motion Tracking ◽  
Robot Navigation ◽  
Tracking System ◽  
Three Dimensional ◽  
Measurement Unit ◽  
Indoor Environments ◽  
Localization Algorithm ◽  
Monte Carlo Localization ◽  
Motion Tracking System

This article presents an enhanced version of the Monte Carlo localization algorithm, commonly used for robot navigation in indoor environments, which is suitable for aerial robots moving in a three-dimentional environment and makes use of a combination of measurements from an Red,Green,Blue-Depth (RGB-D) sensor, distances to several radio-tags placed in the environment, and an inertial measurement unit. The approach is demonstrated with an unmanned aerial vehicle flying for 10 min indoors and validated with a very precise motion tracking system. The approach has been implemented using the robot operating system framework and works smoothly on a regular i7 computer, leaving plenty of computational capacity for other navigation tasks such as motion planning or control.

Low-cost respiratory motion tracking system

2008 ◽  
Author(s):  
Mohammed Goryawala ◽  
Misael Del Valle ◽  
Jiali Wang ◽  
James Byrne ◽  
Juan Franquiz ◽  
...  
Keyword(s):  
Motion Tracking ◽  
Respiratory Motion ◽  
Tracking System ◽  
Low Cost ◽  
Motion Tracking System

scholarly journals Evaluation of the SteamVR Motion Tracking System with a Custom-Made Tracker

2021 ◽  
Vol 11 (14) ◽  
pp. 6390
Author(s):  
Marcin Maciejewski
Keyword(s):  
Motion Tracking ◽  
Tracking System ◽  
Training System ◽  
Random Errors ◽  
Operational Conditions ◽  
Custom Made ◽  
Systematic And Random Errors ◽  
Position And Orientation ◽  
Motion Tracking System ◽  
System Operating

The paper presents the research of the SteamVR tracker developed for a man-portable air-defence training system. The tests were carried out in laboratory conditions, with the tracker placed on the launcher model along with elements ensuring the faithful reproduction of operational conditions. During the measurements, the static tracker was moved and rotated in a working area. The range of translations and rotations corresponded to the typical requirements of a shooting simulator application. The results containing the registered position and orientation values were plotted on 3D charts which showed the tracker’s operation. Further analyses determined the values of the systematic and random errors for measurements of the SteamVR system operating with a custom-made tracker. The obtained results with random errors of 0.15 mm and 0.008° for position and orientation, respectively, proved the high precision of the measurements.

Real-time orthognathic surgical simulation using a mandibular motion tracking system

2007 ◽  
Vol 12 (2) ◽  
pp. 91-104 ◽  
Author(s):  
Kenji Fushima ◽  
Masaru Kobayashi ◽  
Hiroaki Konishi ◽  
Kennichi Minagichi ◽  
Takeshi Fukuchi
Keyword(s):  
Real Time ◽  
Motion Tracking ◽  
Surgical Simulation ◽  
Tracking System ◽  
Motion Tracking System

A Study of Tracking System Using Multiple Emitter Towers

2013 ◽  
Vol 694-697 ◽  
pp. 927-935 ◽  
Author(s):  
Yi Sun ◽  
Tao Ma ◽  
Chia Yung Han ◽  
Joseph Ross ◽  
William Wee
Keyword(s):  
Coordinate Transformation ◽  
Motion Tracking ◽  
Tracking System ◽  
Transformation Method ◽  
Tracking Accuracy ◽  
Working Space ◽  
Frontal Part ◽  
Motion Tracking System ◽  
Coordinate Transformation Method

This paper presents a simple and accurate coordinate transformation method for extending the tracking space of the Intersense IS-900 spatial and motion tracking system using multiple pre-configured emitter towers to form the emitter constellation, but without resorting to the use of a surveyor machine. The proposed approach uses the differences of positional coordinate readings from each emitter tower among a set of commonly viewed spatial points to calculate the parameters needed to define the coordinate transformation. By applying this method, the tracking accuracy using the entire emitter constellation can be achieved by less than 0.5 inches error in most of the working space, and as low as 0.2 inches error in the frontal part of the working space.

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