Except for aerodynamics forces, all vehicle excitation forces are generated at the tyre-road interface. Considering low speed applications, such as terramechanics where the aerodynamics force are negligible, the road-tyre interaction is of extreme importance. Crucial variables which govern the forces generated at the tyre-road interface are tyre side-slip angle, tyre longitudinal slip ratio and terrain pro le. Solutions to measure these variables exist for smooth hard roads but the solutions experience challenges on rough and o -road terrain. Digital Image Correlation is concerned with tracking the changes of a scene in a sequence of images or in images obtained from multiple viewpoints. These methods are frequently used in micro and nano-scale mechanical testing due to its ease of implementation and use as well as its non-contact approach. As a result these techniques are being implemented in many elds from material testing, physics, lm animations and engineering. The aim of this thesis is to investigate the applications of Digital Image Correlation in vehicle dynamics using cost e cient o -the-shelf digital cameras and lenses. The following three vehicle dynamic problems are investigated: The measurement of the vehicle side-slip angle, longitudinal slip-ratio of a pneumatic tyre and high delity terrain pro ling. The vehicle side-slip angle can be used as a measure of the vehicle stability and therefore be used to improve the e ectiveness of vehicle stability controllers. The tyre side-slip angle is also a vital measurement in characterising the lateral force characteristics of pneumatic tyres. A planar measuring method using Digital Image Correlation is shown to accurately measure the side-slip angle. The method is expanded by developing two additional algorithms which can measure all translational and rotational velocities. These methods are validated on both smooth surfaces and rough o -road terrain. A method is also implemented whereby the longitudinal slip ratio of a tyre can be measured using a single camera. Therefore, doing away with the conventional method of using three independent measurement systems. Features in the contact patch, encompassing both the tyre and the road, are tracked in a sequence of images. The features are classi ed into features lying on the tyre, road and outliers using a clustering algorithm. This enables the system to determine the tyre and road velocities from which the slip ratio is determined. High delity terrain pro ling is performed using a calibrated stereographic rig to obtain a three dimensional point cloud of the scene which is being viewed. The point cloud generated at one sample contains a grid of points encompassing a large area with points spaced both laterally and longitudinally. Overlapping point clouds are generated and joined using various registration techniques. The joined point clouds are sub-sampled to obtain a regularised grid of point containing a single point cloud of non overlapping points. The proposed techniques create new possibilities in the eld of vehicle dynamics. Enabling the side-slip angle to be measured in rough of road conditions while providing additional measurements. The longitudinal slip ratio which is measured directly at the contact patch could pave the way for better understanding the mechanism of the longitudinal tyre force generation. The inexpensive road pro ling systems enables multiple sensors to be used in terramechanics tests to determine the impact of a vehicle on the environment. The thesis presents the mere tip of the ice berg concerning digital image correlation used in vehicle dynamics with many more possibilities waiting to be discovered. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Mechanical and Aeronautical Engineering / PhD / Unrestricted

L'emploi d'un retour visuel dans le but d'effectuer une commande en boucle fermée de robot s'est largement répandu et concerne de nos jours tous les domaines de la robotique. Un tel retour permet d'effectuer une comparaison entre un état désiré et l'état actuel, à l'aide de mesures visuelles. L'objectif principal de cette thèse consiste à concevoir plusieurs types de lois de commande cinématiques par vision stéréo. Ceci concerne aussi l'étude de la stabilité du système en boucle fermée et la convergence des fonctions de tâche. C'est essentiellement le découplage des lois de commandes cinématiques en rotation et en translation qui est recherché ici, selon le nombre d'indices visuels considérés.Les mesures visuelles utilisées dans cette thèse sont les lignes droites 3D. Les intérêts apportés à ce type de mesures visuelles sont la robustesse contre le bruit, et la possibilité de représenter d'autres primitives comme des couples de points ou de plans par la modélisation de Plücker. / Closing the control loop of a manipulator robot with vision feedback is widelyknown. It concerns nowadays all areas of robotics. Such a return can make a comparison between a desired state and current state, using visual measurements. The main objective of this doctoral thesis is to design several types of kinematic control laws for stereo visual servoing. It strongly involves the formalism of the task function which is a well-known and useful mathematical tool to express the visual error as a function of state vectors.We have investigated the decoupling between the rotational and translational velocities control laws together with the epipolar constraint with a stereo visual feedback.That is why, the visual measurements and features used in this thesis are the 3Dstraight lines.The interests of this type of visual features rely on the robustness against the noise, and the possibility to represent straight lines or other features like points or planes pairs by the Plücker coordinates, as a 3D straight line can be represented as well by two points or the intersection of two planes. This makes all the control laws designed in this thesis valid for another visual features like points

In live sound reinforcements scenarios, the majority of the audience is placed in a non- optimal listening position and will not experience the stereophonic image as intended by the mixing engineer. This study was conducted to examine the impact of a central loudspeaker source and phantom center, on the stereophonic image from different listening positions. Sixteen subjects, consisting of audio engineering students and professionals, were subjected to an optimal and non-optimal listening position and a three channel and stereo system, and was asked to estimate the perceived location of a stimulus, consisting of a 40 ms 1 kHz tone, placed on five different locations within the panorama. The results of these test were then summarized and analyzed by utilizing three t-tests in order to examine; the difference between perceived and intended location for each combination of system configuration and listening position, the difference between the listening positions and the difference between system configurations. The results show that a three-channel system is less affected by the listening position than a stereo system, indicating that a three-channel system can provide a more similar experience to audience members regardless of their listening position. However, the preference of system configuration is not examined and should be examined before making the claim that one system configuration is superior. The number of t-test conducted may also have impacted the results and provided a false significance. Subsequent studies could be made to confirm or reject the results of this study.

Tonmeisters tune the sound of music productions. Besides aspects like spectral bal- ance, loudness and dynamics, spaciousness plays an important role. Music of different genres tends towards different degrees of spaciousness due to generic aesthetic ideals and practical reasons. In this paper, we compare the degree of spaciousness as intended by the Tonmeister and perceived by the listener. 150 music excerpts from 5 different genres (electronica, classical, jazz, rock and ethno) are analyzed. The Tonmeister’s intention is derived from the literature and from analysis with a goniometer. The listeners perception is obtained from a listening test with 13 participants. The listening test revealed different adjectives for each genre relating to a spacious perception. We found that general rules as suggested in the literature are barely reflected in the goniometer results or the subjective impressions. Subjective impressions are largely contradictory.

Indiana University-Purdue University Indianapolis (IUPUI) / Obstacle detection, avoidance and path finding for autonomous vehicles requires precise information of the vehicle’s system environment for faultless navigation and decision making. As such vision and depth perception sensors have become an integral part of autonomous vehicles in the current research and development of the autonomous industry. The advancements made in vision sensors such as radars, Light Detection And Ranging (LIDAR) sensors and compact high resolution cameras is encouraging, however individual sensors can be prone to error and misinformation due to environmental factors such as scene illumination, object reflectivity and object transparency. The application of sensor fusion in a system, by the utilization of multiple sensors perceiving similar or relatable information over a network, is implemented to provide a more robust and complete system information and minimize the overall perceived error of the system. 3D LIDAR and monocular camera are the most commonly utilized vision sensors for the implementation of sensor fusion. 3D LIDARs boast a high accuracy and resolution for depth capturing for any given environment and have a broad range of applications such as terrain mapping and 3D reconstruction. Despite 3D LIDAR being the superior sensor for depth, the high cost and sensitivity to its environment make it a poor choice for mid-range application such as autonomous rovers, RC cars and robots. 2D LIDARs are more affordable, easily available and have a wider range of applications than 3D LIDARs, making them the more obvious choice for budget projects. The primary objective of this thesis is to implement a smart and robust sensor fusion system using 2D LIDAR and a stereo depth camera to capture depth and color information of an environment. The depth points generated by the LIDAR are fused with the depth map generated by the stereo camera by a Fuzzy system that implements smart fusion and corrects any gaps in the depth information of the stereo camera. The use of Fuzzy system for sensor fusion of 2D LIDAR and stereo camera is a novel approach to the sensor fusion problem and the output of the fuzzy fusion provides higher depth confidence than the individual sensors provide. In this thesis, we will explore the multiple layers of sensor and data fusion that have been applied to the vision system, both on the camera and lidar data individually and in relation to each other. We will go into detail regarding the development and implementation of fuzzy logic based fusion approach, the fuzzification of input data and the method of selection of the fuzzy system for depth specific fusion for the given vision system and how fuzzy logic can be utilized to provide information which is vastly more reliable than the information provided by the camera and LIDAR separately

This thesis deals with algorithms of visual odometry and its application on the experimental vehicle Car4. The first part contains different researches in this area on which the solution process is based. Next chapters introduce theoretical design and ideas of monocular and stereo visual odometry algorithms. The third part deals with the implementation in the software MATLAB with the use of Image processing toolbox. After tests done and based on real data, the chosen algorithm is applied to the vehicle Car4 used in practical conditions of interior and exterior. The last part summarizes the results of the work and address the problems which are asociated with the application of visual obmetry algorithms.

This thesis explains how Oriented FAST and rotated BRIEF SLAM (ORB-SLAM), one of the best visual SLAM solutions, works indoor and evaluates the technique performance for three different cameras: monocular camera, stereo camera and RGB-D camera. Three experiments are designed to find the limitation of the algorithm. From the experiments, the RGB-D SLAM gives the most accurate result for the indoor environment. The monocular SLAM performs better than stereo SLAM on our platform due to limited computation power. It is expected that stereo SLAM provides better results by increasing the experimental platform computational power. The ORBSLAM results demonstrate the applicability of the approach for the autonomous navigation and future autonomous cars.

Binaural sound reproduction is most commonly made with headphones, although little research has been dedicated towards evaluating the sound of binaural for headphones reproduced on loudspeakers, which is the purpose of this thesis. An experimental quantitative method was designed in order to measure the objective effect of binaural processing both on headphones and loudspeakers so that they could be compared. Sine sweeps covering the entire audible frequency spectrum were processed with an ambisonics spatializer at different azimuth and distance parameters and then downmixed to binaural. The same source signal was also panned with a traditional equal-power panning law. Both was played back through headphones and loudspeakers then recorded with a dummy head. The recordings were deconvolved into graphs displaying their frequency responses. The results show that binaural sound produce different spectral distortion depending on the panning position on both headphones and loudspeakers, although additional subjective evaluation such as listening tests are required to determine the actual usefulness of binaural sound through loudspeakers.

Computational models of collective motion have yielded many insights about the way that groups of animals or simulated particles may move together and self-organize. Recent literature has compared predictions of models with large datasets of detailed observations of animal behavior, and found that there are important discrepancies, leading researchers to reexamine some of the most widely used assumptions. We introduce FlockOpt, an optimization-based, variable-speed, self-propelled particle model of collective motion that addresses important shortcomings of earlier models. In our model, each particle adjusts its velocity by performing a constrained optimization of a locally-defined objective function, which is computed at each time step over the kinematics of the particle and the relative position of neighboring particles. Our model explains how ordered motion can arise in the absence of an explicitly prescribed alignment term and simulations performed with our model exhibit a wide variety of patterns of motion, including several not possible with popular constant-speed models. Our model predicts that variations in speed and heading of particles are coupled due to costs associated with changes in relative position. We have found that a similar coupling effect may also be present in the flight of groups of gregarious bats. The Mexican Free-tailed bat (Tadarida brasiliensis) is a gregarious bat that forms large maternity colonies, containing hundreds of thousands to millions of individuals, in the southwestern United States in the summer. We have developed a protocol for calibrating cameras used in stereo videography and developed guidelines for data collection. Our field protocol can be deployed in a single afternoon, requiring only short video segments of light, portable calibration objects. These protocols have allowed us to reconstruct the three-dimensional flight trajectories of hundreds of thousands of bats in order to use their flight as a biological study system for our model.

The report describes the thesis project with the aim of fusing an arbitrary sequence of stereo measurements into a global 3D representation in real-time. The proposed method involves an octree-based signed distance function for representing the 3D environment, where the geomtric data is fused together using a cumulative weighted update function, and finally rendered by incremental mesh extraction using the marching cubes algorithm. The result of the project was a prototype system, integrated into a real-time stereo reconstruction system, which was evaluated by benchmark tests as well as qualitative comparisons with an older method of overlapping meshes. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>