A real time operating system based test-bed for autonomous vehicle navigation

Research and experiments on ... Autonomous Navigation Schemes and Algorithms need an efficient test-bed for objective performance analysis. These algorithms often require sensor inputs from the systems such as the speed and steering sensors to apply feedback control action. An efficient test-bed provides status of all sensors and records of all previous sensor values is very desirable. This work involves developing for such a test-bed to support research on Autonomous Navigation schemes and Algorithms involved in these applications. Different approaches are analyzed and an optimum approach to design test-bed is implemented --Abstract, page iii

Unified Behavior Framework for Reactive Robot Control in Real-Time Systems

Endeavors in mobile robotics focus on developing autonomous vehicles that operate in dynamic and uncertain environments. By reducing the need for human-in- the-loop control, unmanned vehicles are utilized to achieve tasks considered dull or dangerous by humans. Because unexpected latency can adversely affect the quality of an autonomous system\u27s operations, which in turn can affect lives and property in the real-world, their ability to detect and handle external events is paramount to providing safe and dependable operation. Behavior-based systems form the basis of autonomous control for many robots. This thesis presents the unified behavior framework, a new and novel approach which incorporates the critical ideas and concepts of the existing reactive controllers in an effort to simplify development without locking the system developer into using any single behavior system. The modular design of the framework is based on modern software engineering principles and only specifies a functional interface for components, leaving the implementation details to the developers. In addition to its use of industry standard techniques in the design of reactive controllers, the unified behavior framework guarantees the responsiveness of routines that are critical to the vehicle\u27s safe operation by allowing individual behaviors to be scheduled by a real-time process controller. The experiments in this thesis demonstrate the ability of the framework to: 1) interchange behavioral components during execution to generate various global behavior attributes; 2) apply genetic programming techniques to automate the discovery of effective structures for a domain that are up to 122 percent better than those crafted by an expert; and 3) leverage real-time scheduling technologies to guarantee the responsiveness of time critical routines regardless of the system\u27s computational load

Computer vision libraries for trailer truck testbed using open source computer vision libraries

Computer Vision is a field that aims at understanding and analyzing images from the real world to produce numerical and symbolical data. It is a first step at duplicating the capabilities of human vision by electronically understanding the image and perceiving its features. This work aims at providing some of the features of a human eye to a trailer truck. These features include getting a 3D wireframe from continuous images and prediction of the next position of the objects in view, while the truck is moving. The thesis has been divided into 3 sections. First section is acquiring images in real time. Second section is the preprocessing of images to achieve edges and points in the image, and the third section is converting the edges and the points into 3D wireframe and predicting of the next position of the image. OpenCV library and Point cloud libraries are used in this process to facilitate operations on 2D and 3D images --Abstract, page iii

Generic Multisensor Integration Strategy and Innovative Error Analysis for Integrated Navigation

A modern multisensor integrated navigation system applied in most of civilian applications typically consists of GNSS (Global Navigation Satellite System) receivers, IMUs (Inertial Measurement Unit), and/or other sensors, e.g., odometers and cameras. With the increasing availabilities of low-cost sensors, more research and development activities aim to build a cost-effective system without sacrificing navigational performance. Three principal contributions of this dissertation are as follows: i) A multisensor kinematic positioning and navigation system built on Linux Operating System (OS) with Real Time Application Interface (RTAI), York University Multisensor Integrated System (YUMIS), was designed and realized to integrate GNSS receivers, IMUs, and cameras. YUMIS sets a good example of a low-cost yet high-performance multisensor inertial navigation system and lays the ground work in a practical and economic way for the personnel training in following academic researches. ii) A generic multisensor integration strategy (GMIS) was proposed, which features a) the core system model is developed upon the kinematics of a rigid body; b) all sensor measurements are taken as raw measurement in Kalman filter without differentiation. The essential competitive advantages of GMIS over the conventional error-state based strategies are: 1) the influences of the IMU measurement noises on the final navigation solutions are effectively mitigated because of the increased measurement redundancy upon the angular rate and acceleration of a rigid body; 2) The state and measurement vectors in the estimator with GMIS can be easily expanded to fuse multiple inertial sensors and all other types of measurements, e.g., delta positions; 3) one can directly perform error analysis upon both raw sensor data (measurement noise analysis) and virtual zero-mean process noise measurements (process noise analysis) through the corresponding measurement residuals of the individual measurements and the process noise measurements. iii) The a posteriori variance component estimation (VCE) was innovatively accomplished as an advanced analytical tool in the extended Kalman Filter employed by the GMIS, which makes possible the error analysis of the raw IMU measurements for the very first time, together with the individual independent components in the process noise vector

Platforms for prototyping minimally invasive instruments

The introduction of new technologies in medicine is often an issue because there are many stages to go through, from the idea to the approval by ethical committees and mass production. This work covers the first steps of the development of a medical device, dealing with the tools that can help to reduce the time for producing the laboratory prototype. These tools can involve electronics and software for the creation of a “universal”' hardware platform that can be used for many robotic applications, adapting only few components for the specific scenario. The platform is created by setting up a traditional computer with operating system and acquisition channels aimed at opening the system toward the real environment. On this platform algorithms can be implemented rapidly, allowing to assess the feasibility of an idea. This approach lets the designer concentrate on the application rather than on the selection of the appropriate hardware electronics every time that a new project starts. In the first part an overview of the existing instruments for minimally invasive interventions that can be found as commercial or research products is given. An introduction related to hardware electronics is presented with the requirements and the specific characteristics needed for a robotic application. The second part focuses on specific projects in MIS. The first project concerns the study and the development of a lightweight hand-held robotic instrument for laparoscopy. Motivations are related to the lack of dexterous hand-held laparoscopic instruments. The second project concerns the study and the presentation of a prototype of a robotic endoscope with enhanced resolution. The third project concerns the development of a system able to detect the inspiration and the expiration phases. The aim is to evaluate the weariness of the surgeon, since breathing can be related to fatigue

Xenomai Lab: uma plataforma para controlo digital em tempo-real

Mestrado em Engenharia Electrónica e TelecomunicaçõesXenomai Lab is a free software suite that allows a user to graphically design control systems using block diagrams. The designed system can be executed in real-time with operating frequencies of up to 10KHz using the Xenomai framework. Execution can be merely a numerical simulation or an interaction with the real-world via input/output blocks. Several useful blocks are included in the default installation, such as an oscilloscope, a signal generator, MATLAB setpoint profile loader, and others. A rich set of documentation and examples is also provided. Development of Xenomai Lab was supported by a thorough study of real-time operating systems based on GNU/Linux. The performances of standard Linux, the PREEEMPT_RT patchset, RTAI and Xenomai were benchmarked using a standard test. This allowed for a direct comparison between them. Xenomai was found to have the ideal balance between performance and ease of use, with scheduling jitter bellow 35μs on a desktop computer. Ease of use was one of Xenomai Lab’s main goals. This distinguishes it from alternatives. Control algorithms are programmed in C and no prior knowledge of Xenomai, or real-time operating systems in general for that matter, is needed. This makes our system adequate for use by control engineers unfamiliar with GNU/Linux and by entry level students of control engineering, robotics, and other equally technical areas. Advanced users will feel right at home.O Xenomai Lab é uma plataforma open-source que permite a um utilizador projectar gráficamente um sistema de controlo recorrendo a um diagrama de blocos. O sistema projectado pode ser executado em tempo-real a uma frequência de operação de até 10KHz pela framework de tempo-real Xenomai. Execução pode ser uma mera simulação numérica, ou uma interacção com o mundo real recorrendo a blocos de input e output. A instalação traz de origem vários blocos potencialmente úteis, como um osciloscópio, um gerador de sinais, interface com perfis de setpoint feitos em MATLAB, entre outros. É também incluída documentação e alguns exemplos ilustrativos. O desenvolvimento do Xenomai Lab teve por base uma pesquisa exaustiva de sistemas operativos de tempo-real baseados em GNU/Linux. As performances de Linux, do patch PREEEMPT_RT, do RTAI e do Xenomai foram medidas recorrendo a um mesmo teste. Desta forma, tornou-se possível fazer uma comparação directa entre as diferentes tecnologias. De acordo com os nossos testes, o Xenomai apresenta um balanço ideal entre performance e facilidade de utilização. O jitter de escalonamento esteve sempre abaixo de 35μs num computador de secretária. O Xenomai Lab foi desenvolvido de forma a ser fácil de utilizar. Esta é a característica chave que o distingue de software semelhante. Algoritmos de controlo são programados em linguagem C, não sendo necessário nenhum conhecimento específico de Xenomai ou mesmo de sistemas de tempo-real em geral. Assim, o Xenomai Lab é adequado para engenheiros da área de controlo sem experiência em GNU/Linux ou sistemas operativos de tempo-real ou mesmo estudantes de engenharia de controlo, robótica e outras áreas técnicas. Utilizadores avançados sentir-se-ão imediatamente em casa

Software framework for high precision motion control applications

Developing a motion control system requires much effort in different domains. Namely control, electronics and software engineering. In addition to these, there are the system requirements which may be completely different to these spanning from biomedical engineering to psychology. Collaboration between these fields is vital, however these fields should be involved only as much as they are needed to be in the fields of expertise of the others. Several software frameworks exist for the creation of robotics applications. But currently there is no standard for the creation of mechatronics systems nor is there a complete software package that can deal with all aspects in the programming of such systems. Existing frameworks each have their advantages and disadvantages, however they generally have limited or no dedicated structure for the development of the motion control aspect of the problem and deal extensively with the robotenvironment interactions and inter mechanism communications. Dealing with the higher levels of the problem, they are usually not well suited for hard realtime; since the interactions can run on soft realtime constraints. The software framework proposed in this study aims to achieve a level of abstraction between the different domains utilized within a system. The aim in using the framework is to achieve a sustainable software structure for the system. Sustainability is an important part of systems, as it permits a system to evolve with changing requirements and variable hardware, with the ultimate goal of having robust software that can be utilized on different platforms and with other systems using an abstraction layer between the hardware and the software. This ensures that the system can be migrated from a processing platform to any other platform and also from one set of hardware to another. The framework was tested on several systems that have precision motion control requirements such as a 10 degree of freedom micro assembly workstation, a modular micro factory and a haptic system with time delay. Each of the systems works in di erent processing platforms and have different motion control requirements. The achieved results from the implementations show that the software framework is an important tool for the development of motion control software

Design and Control of a Compact 6-Degree-of-Freedom Precision Positioner with Linux- Based Real-Time Control

This dissertation presents the design, control, and implementation of a compact highprecision multidimensional positioner. This precision-positioning system consists of a novel concentrated-field magnet matrix and a triangular single-moving part that carries three 3-phase permanent-magnet planar-levitation-motor armatures. Since only a single levitated moving part, namely the platen, generates all required fine and coarse motions, this positioning system is reliable and potentially cost-effective. The three planar levitation motors based on the Lorentz-force law not only produce the vertical force to levitate the triangular platen but also control the platen's position and orientation in the horizontal plane. Three laser distance sensors are used to measure vertical, x-, and yrotation motions. Three 2-axis Hall-effect sensors are used to determine lateral motions and rotation motion about the z-axis by measuring the magnetic flux density generated by the magnet matrix. This positioning system has a total mass of 1.52 kg, which is the minimized mass to produce better dynamic performance. In order to reduce the mass of the moving platen, it is made of Delrin with a mass density of 1.54 g/cm3 by Computer Numerical Controlled (CNC) machining. The platen can be regarded a pure mass, and the spring and damping effects are neglected except for the vertical dynamic. Single-input single-output (SISO) digital lead-lag controllers and a multivariable Linear Quadratic Gaussian (LQG) controller were designed and implemented. Real-time control was performed with the Linux-Ubuntu operating system OS. Real Time Application Interface (RTAI) for Linux works with Comedi and Comedi libraries and enables closed-loop real-time control. One of the key advantages of this positioning stage with Hall-effect sensors is the extended travel range and rotation angle in the horizontal mode. The maximum travel ranges of 220 mm in x and 200 mm in y were achieved experimentally. Since the magnet matrix generates periodical sinusoidal flux densities in the x-y plane, the travel range can be extended by increasing the number of magnet pitches. The rotation angle of 12 degrees was achieved in rotation around z. The angular velocities of 0.2094 rad/s and 4.74 rad/s were produced by a 200-mm-diameter circular motion and a 30-mm-diameter spiral motion, respectively. The maximum velocity of 16.25 mm/s was acquired from over one pitch motion. The maximum velocity of 17.5 mm/s in a 8-mm scanning motion was achieved with the acceleration of 72.4 m/s2. Step responses demonstrated a 10-um resolution and 6-um rms position noise in the translational mode. For the vertical mode, step responses of 5 um in z, 0.001 degrees in roation around x, and 0.001 degrees in rotation around y were achieved. This compact single-moving-part positioner has potential applications for precisionpositioning systems in semiconductor- manufacturing