Sandro Mihradi

Gait Parameters Determination by 2D Optical Motion Analyzer System

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.

Development of an optical motion-capture system for 3D gait analysis

This work presents the development of an optical motion-capture system for 3D gait analysis. The system consists of two video cameras with speed of 25 fps, flash lighter, LED markers, and two PCs and technical computing software, which are used to acquire marker motion attached to human body during walking. The developed system has five module to obtain real coordinate of markers, i.e. pre-processing, camera calibration, marker detection and tracking, 3D reconstruction, and post-processing module. In the experiment, two camcorders are synchronized using flashlight. The recorded videos from experiment are extracted into frames. The synchronized framesare converted into binary images and marker position can be detected and tracked using least distance method. 3D Direct Linear Transformation method has been used to reconstruct 3D marker position in real coordinate. The marker positions data obtained from experiment could then be used for further kinematics and kinetics analysis of human gait.

Development of an affordable system for 2D kinematics and dynamics analysis of human gait

Development of a low-cost, yet reliable, system for 2D gait analysis is presented in this paper. The system consists of a home video camera with speed of 25 fps, LED markers, PC and a technical computing software, which are used for capturing and processing the digital image of markers attached to human body during motion. In the experiments, a person is instructed to walk in a specially arranged measurement area. The recorded images are then digitally processed to detect and track the 2D coordinate of the markers over time. To conduct a dynamics analysis, a mathematical formulation for human motion is constructed where the body is modeled by a system of five rigid bars connected by joints. Finally, a program is developed to plot and calculate the kinematics and dynamics data of human gait, where the markers position data over time, and other variables such as dimensions and weight of the body are used as the input in the program.

Tracking of Markers for 2D and 3D Gait Analysis Using Home Video Cameras

This work presents the development of an affordable optical motion-capture system which uses home video cameras for 2D and 3D gait analysis. The 2D gait analyzer system consists of one camcorder and one PC while the 3D gait analyzer system uses two camcorders, a flash and two PCs. Both systems make use of 25 fps camcorder, LED markers and technical computing software to track motions of markers attached to human body during walking. In the experiment for 3D gait analyzer system, the two cameras are synchronized by using flash. The recorded videos for both systems are extracted into frames and then converted into binary images, and bridge morphological operation is applied for unconnected pixel to facilitate marker detection process. Least distance method is then employed to track the markers motions, and 3D Direct Linear Transformation is used to reconstruct 3D markers positions. The correlation between length in pixel and in the real world resulted from calibration process is used to reconstruct 2D markers positions. To evaluate the reliability of the 2D and 3D optical motion-capture system developed in the present work, spatio-temporal and kinematics parameters calculated from the obtained markers positions are qualitatively compared with the ones from literature, and the results show good compatibility.

Development of a 3D Gait Measurement Protocol for Amputees Walking on Treadmill

Walking motion is actually a complex activity since it involves many body parts, especially the lower limb. Due to the needs for gait analysis in many medical applications, Biomechanics Research Team at ITB has developed an affordable optical motion analyzer to measure motions of subject walking over ground. However, the needs for multicycles gait data is better met by measuring subjects walking on treadmill. This paper discusses the modification of the developed motion analyzer to accommodate data acquisition of subject walking on treadmill, including those of transfemoral amputees. Seven markers, two 95 fps cameras, a dual-channel Camera Link Acquisition NI PCIe-1430 frame grabber, and a workstation are employed in the optical motion analyzer system. The speed displayed on the treadmill is evaluated. Additional equipment such as the modified hydraulic engine crane and the body harness are introduced to ensure the safety of amputees and avoid the risk of falling down while walking on the treadmill. The modified motion analyzer system is then used to obtain gait parameters of normal (37 males and 31 females) and three amputee subjects. The gait parameters of normal subjects in the treadmill walking shows that there is a decrease in the stride length and range of motion, and increase in the cadence due to walking adaptation. There are also phase shifting and increase in the range of motion for amputee subjects compared to the normal subjects which imply that there is an extra work done by the residual limb in doing walking movement and the amputee subjects try to balance their walking on the treadmill.

Stress-Distribution around Pin-Loaded Hole for Orthotropic Laminates

Stresses were calculated for orthotropic laminate plate loaded by a frictionless pin in a circular hole of the same diameter. These calculations were based on finite-element analysis for five laminates; 00, [±450]s, [00/900]s,[00/±450]s, and quasi-isotropic [00/±450/900]s. stress distribution, based on nominal bearing stress, were determined for wide ranges of the ratios of width to diameter and edge distance to diameter. Orthotropic had a significant influence on both the magnitude and location of the maximum tensile stress concentration on the boundary of the hole. The laminates with 00 plies developed the peak tensile stress near the ends of the pin-hole contact arc. But the ±450 laminates had peaks where ply fiber were tangent to the hole. The finite width and edge distances strongly influenced the tensile stress concentration. In contrast, the finite widths and edge distances had little effect on bearing stress concentration. For the practical range w/d = 2, the peak tensile stresses were as much as 50 percent larger than the infinite-laminate value. For e/d=1, these stresses were greater 60 percent than infinite-laminate value. In contrast, the finite width and edge distance had little effect on bearing stress concentrations.

3D Reconstruction and Stress Analysis of the Free End Second Premolar Root Form Dental Implant

Stress distributions that occur in the free end second premolar tooth and its root form dental implant replacement were evaluated using finite element method. In the modelling process, 3D reconstructions were performed. Instead of doing it manually, the 3D reconstruction in this paper was done using cone beam computed tomography (CBCT) scanning process. The 3D reconstruction method used in this paper, is considerably faster than the traditional manual 3D reconstruction method. In order to mimic the actual biting force, static load of 200 N was modelled in the vertical direction parallel to the long axis of the tooth which is placed on bite contact at second premolars and dental implant crown. The stress result on root form dental implant is generally higher than the stress on the natural free end second premolar tooth. The stress concentration locations on root form dental implant were also found and will be used in the future to improve the design of root form dental implant.

Design and Fabrication of an Affordable Transfemoral Prosthetic Leg

An invalid is a person with physical or mental abnormalities which hinders their ability of doing normal human activities. One of the aforementioned abnormalities is the loss or malfunction of a body part or organ, such as the human leg. Problems brought about by this disability could be alleviated by the use of prosthetic limbs to restore normal bodily functions [1]. While there are many needs for leg prosthetics in Indonesia, the price of commercially available prosthetic is prohibitively high for most amputees. The current available affordable prosthetics are very basic and employ monocentric knee joints. Here an attempt is made towards acquiring an optimal design of an affordable prosthetic leg using previously developed four-bar knee joint [2,3]. The design is carried out by implementing a systematic design method to arrive at an affordable, yet ones with better performances. The procedure involves a rubric and analyzing various alternatives to arrive at an optimal design conclusion. The evaluation objective is to maximize the performance of the leg and knee prosthetics through an extensive analysis with considerations from various stakeholders, including the potential users, fabricator, and hospitals in Indonesia [4]. The final design of the leg consists of a composite socket, an aluminum pylon, and a solid-ankle cushioned-heel foot design. Its components are modular and compatible with prosthetic industry standards. The knee is made of a combination of polymers and stainless steel and employs a polycentric mechanism in order to satisfy design requirements while keeping costs low [4,5]. The leg and knee were then fabricated according to the analysis results. The total cost of fabrication is approximately 5.5 million IDR, significantly cheaper than commercial prosthetics. The prototype is then tested and examined using a gait analysis system previously developed at Institut Teknologi Bandung by the Biomechanics Research Team [6]. The results show satisfactory performance, albeit with a host of potential improvements.

Design of root canal treatment for dental post application on maxillary central incisor

The main purpose of this study is to evaluate the stress distribution on the maxillary central incisor tooth that has been endodontically treated and restored with silver alloy (silver-palladium) cast post-cores, and to find the optimum wall thickness and height of ferrule for dentin. 3D numerical analysis was done using ANSYS 14® software. Evaluation of stress distribution were done upon eight different variants of maxillary central incisor tooth with ferrule root restoration. The ferrule was modeled with ferrule height variation of 0,5 mm, 1 mm, 1.5 mm, and 2 mm, with constant ferrule wall thickness of 1 mm, while ferrule wall thickness variation of 0.8 mm, 0,9 mm,1 mm, 1,1 mm, and 1.2 mm was modeled with constant ferrule height of 2 mm. Analysis of ferrule which was done with the help of finite element method shows that the optimum ferrule height is 1,5 mm and the optimum ferrule wall thickness is 1 mm. Both models have shown to have the least amount of stress on every components of the tooth. Variants of tooth models have shown to have range of maximum principal stress from 51 MPa to 81,3 MPa and range of minimum principal stress from 12 MPa to 21 MPa, which is far below maximum tensile strength (98 MPa) and compressive strength (297 MPa) of the dentin.

Validity of Kinect for Assessment of Joint Motion during Gait

One of the most common methods employed in gait analysis is the optical measurement method. While many analyzer systems are available commercially, the prices of those systems are rather prohibitive. In this work, an alternative method to obtain gait data using Microsoft KinectTM (Kinect) is investigated. Kinect, a 3D camera system created for gaming purposes, offers an ability which may be suitable for application in gait analysis. It has high mobility, needs no marker, is easy to use, and its price is relatively affordable. However, the performance of Kinect as a measurement tools in gait analysis must be first evaluated. In this work, Kinect is utilized to obtain joint movements of human walking motion to evaluate its suitability as an alternative motion analyzer in gait analyses. The data generated by Kinect are then processed to obtain gait parameters. The resulting parameters are compared to those obtained by 3D Motion Analyzer System that uses multi-camera previously developed. The results show promising prospect for Kinect application in gait analysis.