Department of Mechanical and Mechatronic Engineering

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https://scholar.sun.ac.za/handle/10019.1/109

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Browsing Department of Mechanical and Mechatronic Engineering by browse.metadata.advisor "Blanckenberg, M. M."

Now showing 1 - 6 of 6
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    Application of laser doppler vibrocardiography for human heart auscultation
    (Stellenbosch : Stellenbosch University, 2014-04) Koegelenberg, Suretha; Scheffer, C.; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: This thesis investigates the feasibility of the laser Doppler vibrometer (LDV) for use in the autonomous auscultation of the human heart. As a non-contact measurement device, the LDV could become a very versatile biomedical sensor. LDV, stethoscope, piezoelectric accelerometer (PA) and electrocardiogram (ECG) signals were simultaneously recorded from 20 volunteers at Tygerberg Hospital. Of the 20 volunteers, 17 were confirmed to have cardiovascular disease. 3 patients with normal heart sounds were recorded for control data. The recorded data was successfully denoised using soft threshold wavelet denoising and ensemble empirical mode decomposition. The LDV was compared to the PA in common biomedical applications and found to be equally accurate. The heart sound cycles for each participant were segmented using a combination of ECG data and a simplicity curve. Frequency domain features were extracted from each heart cycle and input into a k-nearest neighbours classifier. It was concluded that the LDV can form part of an autonomous, non-contact auscultation system.
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    Development of distributed control system for SSL soccer robots
    (Stellenbosch : Stellenbosch University, 2013-03) Holtzhausen, David Schalk; Schreve, K.; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: This thesis describes the development of a distributed control system for SSL soccer robots. The project continues on work done to develop a robotics research platform at Stellenbosch University. The wireless communication system is implemented using Player middleware. This enables high level programming of the robot drivers and communication clients, resulting in an easily modifiable system. The system is developed to be used as either a centralised or decentralised control system. The software of the robot’s motor controller unit is updated to ensure optimal movement. Slippage of the robot’s wheels restricts the robot’s movement capabilities. Trajectory tracking software is developed to ensure that the robot follows the desired trajectory while operating within its physical limits. The distributed control architecture reduces the robots dependency on the wireless network and the off-field computer. The robots are given some autonomy by integrating the navigation and control on the robot self. Kalman filters are designed to estimate the robots translational and rotational velocities. The Kalman filters fuse vision data from an overhead vision system with inertial measurements of an on-board IMU. This ensures reliable and accurate position, orientation and velocity information on the robot. Test results show an improvement in the controller performance as a result of the proposed system.
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    Evaluation of active acoustic methodology in diagnosis of pleural effusion
    (Stellenbosch : Stellenbosch University, 2013-03) Minai Zaiem, Hamed; Scheffer, C.; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: Pleural effusion is a common respiratory condition that is characterized by an abnormal collection of fluid in the lung cavity. In this study, an innovation using the transmission of sound into the respiratory system as a novel tool to detect fluid in the lung was developed. First, the method was evaluated on a phantom model of a lung. Based on the results of this test model, the appropriate technique was used in a clinical study. This method has several advantages, such as that is non-invasive, low cost, and easy for clinical review. Two techniques, including analysis of the frequency response of the model and the transient time of transmitted sound in the lung, were evaluated in the phantom models of the human lung. Two phantom models with similar geometry to the human lung, including a healthy model (without fluid in the model) and a pleural effusion model (with bulk of fluid in the model) were developed. These models have acoustical properties similar to the lung parenchyma. To obtain the frequency responses of the model, a sine sweep signal was transmitted into the model and the frequency response of the model was then calculated using the fast Fourier transform. The transient time of the transmitted sound was calculated using a cross correlation method. The results show that the locations of fluid in the model were detectable using both techniques. However, the transient time technique is better than the frequency response technique because it is simple, fast, and has potential for use in a clinical enviorment. Based on the results obtained from the phantoms, the transient time method was performed on both 22 healthy participants and four patients diagnosed with pleural effusion. To perform this technique on human subjects, a data acquisition system was developed. Two types of sound, including a complex chirp sound and a polyphonic sound, were transmitted into the respiratory systems of the participants. The time delay between a reference microphone, located on the trachea of the subject, and eight microphones attached to the chest was computed using a cross correlation method, and the effect of inhalation and lung size on the transient time of transmitted sound on the healthy subject was evaluated. The results show that using transmission of sound in the lung is a promising technique in the diagnosis of pleural effusion.
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    Research into adventitious lung sound signals originating from pulmonary tuberculosis using electronic auscultation
    (Stellenbosch : University of Stellenbosch, 2009-03) Becker, Konrad Wilhelm; Scheffer, C.; Blanckenberg, M. M.; University of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    Pulmonary tuberculosis is a common and potentially deadly infectious disease, commonly affecting the respiratory area. Over one-third of the world’s population is infected with the tuberculosis bacterium. Since pulmonary tuberculosis damages the respiratory area, the sound properties of infected lungs differ from those of non-infected lungs. However, auscultation is often ruled out as a reliable diagnostic technique due to the random position and severity of damage to the lungs as well as requiring the personal and trained judgment of an experienced medical practitioner. This project investigates a possible improvement in the pulmonary diagnostic and treatment field by applying electronic and computer-aided sound analysis techniques to analyze respiratory actions beyond human audible judgment. Respiratory sounds of both healthy subjects and subjects who were infected with pulmonary tuberculosis were recorded from seven locations per lung on both the posterior and anterior chest walls, using self-designed hardware. Adaptive filtering signal and analysis techniques yielded a wide range of signal features. This included analysis for time, frequency and both wheeze and crackle adventitious respiratory sounds. Following the analysis, statistical methods identified the most attractive signal measurements capable of separating the recordings of healthy and unhealthy respiratory sounds. Selected signal features were used with neural network optimization to obtain a successful implementation for the semi-automated identification of healthy and unhealthy respiratory sounds originating from pulmonary tuberculosis, with a performance of over 80% for sensitivity, specificity and accuracy. The success of categorizing the recordings justifies the capabilities of the digital analysis of respiratory sounds and supports an argument for further research and refinement into the assessment of pulmonary tuberculosis by electronic auscultation. Further research is recommended, with improvements justified and highlighted in this report.
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    Robocup small size league : active ball handling system
    (Stellenbosch : Stellenbosch University, 2014-04) Smit, Daniel Gideon Hugo; Schreve, K.; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: The RoboCup offers a research platform to advance robotics and multi-robot cooperation in dynamic environments. This project builds on work previously done to develop a research platform for multi-robot cooperation at Stellenbosch University. This thesis describes the development of an active ball handling system for a robot in the RoboCup Small Size League (SSL). This was achieved by building on the work done in the previous projects. The hardware for the kicker and dribbler mechanisms on the robot were implemented and tested to characterise their capabilities. The kicker was characterised to control the speed at which a ball is kicked and the dribbler for optimal control over a ball. More accurate movement was required and the Proportional Integral and Derivative (PID) controllers for translational and rotational movement on the robot were improved. The test results show an improvement in straight line trajectory tracking when compared to those of the previous controllers. Dribble control sensors were implemented on the robot for successful dribbling by the robot. This resulted in a significant improvement to the dribbling ability of the robot when these sensors are used. This dribbling ability was compared to the dribbling ability of the robot when no feedback was received from the sensors. Lastly a proposed curved trajectory tracking algorithm was tested by combining translational and rotational movement of the robot. This algorithm showed the capabilities of the robot to follow a curved trajectory with the improved translational and rotational controllers.
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    Wireless physiological monitoring system for psychiatric patients
    (Stellenbosch : Stellenbosch University, 2008-12) Rademeyer, A. J.; Scheffer, C.; Blanckenberg, M. M.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    This thesis is concerned with the development and testing of a non-invasive device that is unassailable, and can be placed on an aggressive psychiatric patient to monitor the vital signs of this patient. Two devices, a glove measuring oxygen saturation and another on the dorsal part (back) of the patient measuring heart rate via electrocardiography (ECG), skin temperature and respiratory rate were designed and implemented. The data is transmitted using wireless technology. Both devices connect to one central monitoring station using two separate Bluetooth connections ensuring a total wireless setup. All the hardware and software to measure these variables have been designed and implemented. A Matlab graphical user interface (GUI) was developed for signal processing and monitoring of the vital signs of the psychiatric patient. Detection algorithms were implemented to detect ECG arrhythmias such as premature ventricular contraction and atrial fibrillation. The prototype was manufactured and tested in a laboratory setting on five volunteers. Satisfactory test results were obtained and the primary objectives of the thesis were fulfilled