Evaluation of an active optical system for lower limb motion tracking (original) (raw)
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Biomedical Engineering Letters, 2018
Comparison of results indicates a mean correlation of 99.542% with a standard deviation of 0.834%. The maximum root mean square error of the foot pitch angle measured by the IMU compared with the Vicon Optical Motion Capture System was 3.738º and the maximum error in the same walking trail between two measurements was 9.927º. These results indicate the level of correlation between the two systems. 1 INTRODUCTION Gait analysis has received significant interest in orthopedics and rehabilitation applications [1]; it has important implications in many clinical settings. The term 'Gait analysis' refers to the systematic study of animal locomotion [2], specifically the study of human motion, using equipments to measure body movements and the activity of the muscles [2]. It involves measurement and analysis of measurable parameters such as absolute and relative angles, positions, movement patterns and joints' range of motion. However, monitoring and measuring the human gait characteristics is a sophisticated task and thus, still rarely used for routine clinical evaluation [3]. There are three major commonly accepted methods available for gait analysis. The first and most common method is visual inspection. Second method is goniometric measurements, which is performed by goniometer that provides the range of motion in joints. Third is 3-dimensional marker-based optical motion capture (MBMOCAP) system which is an optoelectronic gait analysis method using optical motion capture for real-time 3-dimensional motion analysis [4] and considered as the standard method of movement analysis [5][6]. This
A Monocular Marker-Free Gait Measurement System
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2000
This paper presents a new, user-friendly, portable motion capture and gait analysis system for capturing and analyzing human gait, designed as a telemedicine tool to monitor remotely the progress of patients through treatment. The system requires minimal user input and simple single-camera filming (which can be acquired from a basic webcam) making it very accessible to nontechnical, nonclinical personnel. This system can allow gait studies to acquire a much larger data set and allow trained gait analysts to focus their skills on the interpretation phase of gait analysis. The design uses a novel motion capture method derived from spatiotemporal segmentation and model-based tracking. Testing is performed on four monocular, sagittal-view, sample gait videos. Results of modeling, tracking, and analysis stages are presented with standard gait graphs and parameters compared to manually acquired data. Index Terms-Automated tracking, gait analysis, human movement, motion analysis. I. INTRODUCTION A. Motivation C URRENT gait measurement methods involve complex marker systems, multiple cameras, a dedicated gait laboratory and trained personnel. This paper presents a simple single-camera system which has low processing time and is usable remote from the filming location and without the need for qualified gait analysts at the data acquisition stage. While this system is not intended to replace marker-based systems, it allows the study of gait to broaden beyond the gait laboratory while providing results comparable to those achievable with standard systems. It has been used, for example, to analyze gait in video clips filmed in another country. It is hoped that its simplicity will encourage therapists and patients to participate in gait studies and make the most of the technology available. B. Marker-Based Systems Marker-based systems are still the most reliable and widely used. However, they require specific equipment and expertise, not accessible outside a gait laboratory. This can be a significant issue when patients are too unwell to travel or when large data sets are required for study. Also, as demonstrated in [1], gait facilities are not readily available to many potential users. Within a gait laboratory, marker placement is still difficult. Marker positions have a significant effect on system output.
The efficacy of a video-based marker-less tracking system for gait analysis
Computer methods in biomechanics and biomedical engineering, 2017
Most clinical gait analyses are conducted using motion capture systems which track retro-reflective markers that are placed on key landmarks of the participants. An alternative to a three-dimensional (3D) motion capture, marker-based, optical camera system may be a marker-less video-based tracking system. The aim of our study was to investigate the efficacy of the use of a marker-less tracking system in the calculation of 3D joint angles for possible use in clinical gait analysis. Ten participants walked and jogged on a treadmill and their kinematic data were captured with a marker and marker-less tracking system simultaneously. The hip, knee and ankle angles in the frontal, sagittal and transverse planes were computed. Root Mean Square differences (RMSdiff) between corresponding angles for each participant's support phase were calculated and averaged to derive the mean within-subject RMSdiff. These within-subject means were averaged to obtain the mean between-subject RMSdiff fo...
Active marker based kinematic and spatio-temporal gait measurement system using LabVIEW vision
2010
This study presents an automated, easy to use, cost-effective, patient-friendly, active marker based gait measurement (GM) system for 2-D tracking and extraction of spatio-temporal parameters of human gait. Active markers, consisting of visible light-emitting diodes (LEDs), were positioned at anatomical landmarks to measure coordinated kinematics of human joints. Acquired image data were processed and analyzed using LabVIEW vision for determination of spatio-temporal parameters.
A multi-sensors system for human motion measurement: Preliminary setup
Gait analysis and human joint motion measurement has been studied extensively in the recent past. Common approaches that have been used include using inertial sensors, multi-camera optical and IR tracking systems, X-ray and fluoroscopy based imaging, force sensors, magnetic sensors and bone-fixed pins for measurement. Soft tissue artifacts (STA) are a common source of error in most type of measurements and the standard procedure in gait analysis has been to use a combination of measurement methods for efficient estimation of joint angles and the link poses. However, there are few studies where a multiple number of methods have been compared and the correlation between results from various approaches studied. In this paper, we propose an outline for measurement for human joint motion using a number of sensors that can give complete information relating to the joints.
Gait Parameters Determination by 2D Optical Motion Analyzer System
2011
In the present work, an optical motion-capture system combined with software for 2D clinical gait analysis is utilized to determine spatiotemporal gait parameters such as stride-length, cadence, cycle-time, and speed as well as joint angles. The developed system consists of a video camera with a maximum speed of 90 fps, LED markers, PC and technical computing software, which are developed for tracking markers attached to human body during motion and to calculate kinematics and kinetics parameters of human gait. Gait data of 60 subjects within the age group between 18 to 49 years are measured as part of an effort to develop normal walking database of Indonesian people. In the experiments, the subject is instructed to walk in a specially-arranged measurement area, which is calibrated using the Direct Linear Transformation (DLT) method. Before the measurement, the body posture of each subject is evaluated to ensure normalcy. To validate the system, the obtained gait data is compared to the available normal walking database, and the results obtained by the system show good compatibility.
Journal of Biomechanics
Skin-mounted marker based motion capture systems are widely used in measuring the movement of human joints. Kinematic measurements associated with skin-mounted markers are subject to soft tissue artifacts (STA), since the markers follow skin movement, thus generating errors when used to represent motions of underlying bone segments. We present a novel ultrasound tracking system that is capable of directly measuring tibial and femoral bone surfaces during dynamic motions, and subsequently measuring six-degree-of-freedom (6-DOF) tibiofemoral kinematics. The aim of this study is to quantitatively compare the accuracy of tibiofemoral kinematics estimated by the ultrasound tracking system and by a conventional skin-mounted marker based motion capture system in a cadaveric experimental scenario. Two typical tibiofemoral joint models (spherical and hinge models) were used to derive relevant kinematic outcomes. Intra-cortical bone pins equipped with optical markers were inserted in the tibial and femoral bones to serve as a reference to provide ground truth kinematics. The ultrasound tracking system resulted in lower kinematic errors than the skin-mounted markers (the ultrasound tracking system: maximum root-mean-square (RMS) error 3.44°for rotations and 4.88 mm for translations, skin-mounted markers with the spherical joint model: 6.32°and 6.26 mm, the hinge model: 6.38°and 6.52 mm). Our proposed ultrasound tracking system has the potential of measuring direct bone kinematics, thereby mitigating the influence and propagation of STA. Consequently, this technique could be considered as an alternative method for measuring 6-DOF tibiofemoral kinematics, which may be adopted in gait analysis and clinical practice.
A low-cost video-based tool for clinical gait analysis
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2009
In physical and rehabilitation medicine physicians need to perform clinical gait analysis to assess patients walking ability. Despite the relevant research on motion tracking, gait analysis technologies are far to be commonly diffused in clinical practice since they are quite expensive, need high-structured laboratories and trained personnel who are not always available. In order to overcome such limitations, this work proposes a low-cost, video-based portable tool for clinical gait analysis which provides the bi-dimensional kinematic analysis of walking. The system processes a video stream by means of tracking different markers placed in five anatomical landmarks of the subject's leg, applying Kalman filter in conjunction with a method that copes with occlusions. The system has been validated on a healthy subject, showing that it is able to reconstruct marker position and leg kinematics even if several occlusions occur.
Acta Orthopaedica, 2011
Background and purpose Invasive methods are more reproducible and accurate than non-invasive ones when it comes to recording knee kinematics, but they are usually less accessible and less safe, mainly due to risk of infection. For this reason, non-invasive methods with passive markers are widely used. With these methods, varying marker sets based on a number of single markers, or sets of markers, known as clusters, are used to track body segments. We compared one invasive method-radiostereometric analysis-with a non-invasive method, an optical tracking system with 15 skin-mounted markers.