A scalable embedded robotics real time platform development architecture in Linux

La manipulación de objetos por medio de robots es elemento crucial de las herramientas avanzadas de automatización. Sin embargo, los mecanismos para controlarlos generalmente son muy específicos y requieren diseños que están profundamente atados al hardware del robot – este tipo de implementaciones resultan en código no reutilizable y optimizaciones de algoritmos que solo funcionan en familias de robots particulares. En este trabajo se presenta una propuesta de arquitectura de software para brazos robóticos que corren en el entorno ya ampliamente utilizado de GNU/Linux. Se aborda la necesidad de una arquitectura de software que sea fácil de implementar y escalable en cuanto a su utilización de recursos para prototipos de robots y sistemas completos funcionales. Se presentan diferentes configuraciones y conceptos relacionados a la manipulación y el control de sistemas robóticos y se presenta una propuesta de un robot como caso de estudio para mostrar las dificultades y ventajas de dicha implementación, así como sus parámetros de desempeño en cuanto a tiempos de respuesta y aplicaciones. Robotic manipulation is crucial element of advanced automation tools, however the methods for controlling it are usually crafted for specific and custom designs that are deeply tied to the hardware of the robotics. These type of implementations results in non-re-usable code and optimization algorithms that only work for specific robotic families. In here we will discuss a software architecture for robotic arms running under the freely and widely available GNU/Linux environment along with its benefits and drawbacks of such. The work here expresses the need for a software architecture that results in an easy to implement and scalable framework for robotics prototyping and real functioning systems. In here we will be discussing different robotic configurations and the concepts associated with manipulating and controlling robotic systems. A robot configuration is used as a case of study where the challenges and benefits of the implementation are discussed along with performance data and applications developed with the framework.Consejo Nacional de Ciencia y Tecnologí

Framework for a space shuttle main engine health monitoring system

A framework developed for a health management system (HMS) which is directed at improving the safety of operation of the Space Shuttle Main Engine (SSME) is summarized. An emphasis was placed on near term technology through requirements to use existing SSME instrumentation and to demonstrate the HMS during SSME ground tests within five years. The HMS framework was developed through an analysis of SSME failure modes, fault detection algorithms, sensor technologies, and hardware architectures. A key feature of the HMS framework design is that a clear path from the ground test system to a flight HMS was maintained. Fault detection techniques based on time series, nonlinear regression, and clustering algorithms were developed and demonstrated on data from SSME ground test failures. The fault detection algorithms exhibited 100 percent detection of faults, had an extremely low false alarm rate, and were robust to sensor loss. These algorithms were incorporated into a hierarchical decision making strategy for overall assessment of SSME health. A preliminary design for a hardware architecture capable of supporting real time operation of the HMS functions was developed. Utilizing modular, commercial off-the-shelf components produced a reliable low cost design with the flexibility to incorporate advances in algorithm and sensor technology as they become available

Development of advanced control strategies for Adaptive Optics systems

Atmospheric turbulence is a fast disturbance that requires high control frequency. At the same time, celestial objects are faint sources of light and thus WFSs often work in a low photon count regime. These two conditions require a trade-off between high closed-loop control frequency to improve the disturbance rejection performance, and large WFS exposure time to gather enough photons for the integrated signal to increase the Signal-to-Noise ratio (SNR), making the control a delicate yet fundamental aspect for AO systems. The AO plant and atmospheric turbulence were formalized as state-space linear time-invariant systems. The full AO system model is the ground upon which a model-based control can be designed. A Shack-Hartmann wavefront sensor was used to measure the horizontal atmospheric turbulence. The experimental measurements yielded to the Cn2 atmospheric structure parameter, which is key to describe the turbulence statistics, and the Zernike terms time-series. Experimental validation shows that the centroid extraction algorithm implemented on the Jetson GPU outperforms (i.e. is faster) than the CPU implementation on the same hardware. In fact, due to the construction of the Shack-Hartmann wavefront sensor, the intensity image captured from its camera is partitioned into several sub-images, each related to a point of the incoming wavefront. Such sub-images are independent each-other and can be computed concurrently. The AO model is exploited to automatically design an advanced linear-quadratic Gaussian controller with integral action. Experimental evidence shows that the system augmentation approach outperforms the simple integrator and the integrator filtered with the Kalman predictor, and that it requires less parameters to tune

Design and analysis of a high performance valve

Most valves available in the fluid power industry today are capable of achieving either a large flow rate or a quick response time; however, often they are unable to deliver both simultaneously. Commercially available valves that can produce both at the same time require complex geometries with multiple actuation stages and piloting pressures, making them expensive components. To establish their active usage in applications across the fluid power industry, a reduction in price for these components is paramount. The Energy Coupling Actuated Valve (ECAV) is capable of solving the large flow rates with fast actuation speeds trade-off by utilizing a new, high performance actuation system. The Energy Coupling Actuator (ECA) is an innovative actuation system that separates the kinetic energy source mass from the actuation mass. Intermittently coupling the actuator to a constantly rotating disk creates an energy transfer from the rotating disk’s kinetic energy to the normally stationary actuator. This intermittent coupling process is controlled by changing the magnetic field inside the actuator’s two coils. Magnetorheological (MR) fluid resides in a 0.5mm fluid gap between the spinning disk and the actuator, and when the magnetic flux builds across this gap, it causes the actuator to move rapidly in a translational movement. The MR fluid changes to a solid between the gap and frictionally binds the actuator to the disk, causing the actuator to move up or down, depending on which coil is actuated on the spinning disk. The liquid-solid conversion from the MR fluid occurs in less than one millisecond and is completely reversible. The shear strength of the fluid is proportional to the magnetic field strength inside the system. The actuator is connected to either a poppet or spool assembly for valve actuation, and the position is controlled through intermittently binding the actuator to the disk. Two valve prototypes, one poppet and one spool type, were machined, and concept validation has been done in both simulation and experimentally. Experimental results show that the poppet reaches a 4mm displacement in 19.8ms opening and 17ms in closing under 33 L/min flow. The spool valve experimentally transitioned in 4.8ms at the same flow rate

Development of an electronic control unit for the T63 gas turbine

Includes bibliographical references.Fundamental research has been undertaken at the SASOL Advanced Fuels Laboratory to investigate the effects of the chemistry and physical properties of both conventional and synthetic jet fuels on threshold combustion. This research was undertaken using a purpose built low pressure continuous combustion test facility. Researchers at the laboratory now wish to examine these effects on an aviation gas turbine in service for which “off-map” scheduling of fuel to the engine would be required. A two phase project was thus proposed to develop this capability; the work of this thesis embodies Phase I of that project

Hybrid Electric Distributed Propulsion for Vertical Takeoff and Landing Aircraft

This research effort explores the interactions between aerodynamics and hybridelectric power system (HEPS) design and control for vertical takeoff and landing (VTOL) aircraft applications. Specifically, this research focuses on embedded distributed electric propulsion systems, for which the aerodynamic forces and moments are inextricably linked to power input. This effort begins by characterizing the performance of two similar embedded propulsion systems using computational fluid dynamics (CFD). From this initial analysis, a wind tunnel model is constructed and the systems are tested across the operating conditions required to characterize the performance of a VTOL aircraft, where 0 deg ≤ α ≤ 90 deg. One of these configurations is selected for evaluating the interaction with the hybrid-power system. An experimental HEPS is constructed based on a small two-stroke internal combustion engine as well, with a rated continuous power output of 2kW. This experiment is used to develop a validated dynamical HEPS model in MATLAB and Simulink, where the control systems are refined and the performance of the system is extended to accommodate the VTOL power demand during transitional flight. A robust control design is developed using a second order sliding mode controller (2-SMC), implemented using the super-twisting algorithm and integrated with classical linear control schemes in an interleaved-cascade architecture. The resulting system has a variable voltage output and a robust response to rapid changes in power demand. Additionally, the HEPS is also demonstrated to fully utilize the mechanical power output capability of the two-stroke engine. Ultimately, the HEPS is demonstrated, via the dynamical model, to be capable of supplying power for an embedded propulsion VTOL aircraft. This performance is further extended with the addition of an actively controlled slack bus, utilizing battery energy storage and a buck-converter integrated with the HEPS control system. In this configuration, the peak power demands of the system can exceed the maximum sustained power threshold (MSPT) of the HEPS

MODERNIZATION OF THE MOCK CIRCULATORY LOOP: ADVANCED PHYSICAL MODELING, HIGH PERFORMANCE HARDWARE, AND INCORPORATION OF ANATOMICAL MODELS

A systemic mock circulatory loop plays a pivotal role as the in vitro assessment tool for left heart medical devices. The standard design employed by many research groups dates to the early 1970\u27s, and lacks the acuity needed for the advanced device designs currently being explored. The necessity to update the architecture of this in vitro tool has become apparent as the historical design fails to deliver the performance needed to simulate conditions and events that have been clinically identified as challenges for future device designs. In order to appropriately deliver the testing solution needed, a comprehensive evaluation of the functionality demanded must be understood. The resulting system is a fully automated systemic mock circulatory loop, inclusive of anatomical geometries at critical flow sections, and accompanying software tools to execute precise investigations of cardiac device performance. Delivering this complete testing solution will be achieved through three research aims: (1) Utilization of advanced physical modeling tools to develop a high fidelity computational model of the in vitro system. This model will enable control design of the logic that will govern the in vitro actuators, allow experimental settings to be evaluated prior to execution in the mock circulatory loop, and determination of system settings that replicate clinical patient data. (2) Deployment of a fully automated mock circulatory loop that allows for runtime control of all the settings needed to appropriately construct the conditions of interest. It is essential that the system is able to change set point on the fly; simulation of cardiovascular dynamics and event sequences require this functionality. The robustness of an automated system with incorporated closed loop control logic yields a mock circulatory loop with excellent reproducibility, which is essential for effective device evaluation. (3) Incorporating anatomical geometry at the critical device interfaces; ascending aorta and left atrium. These anatomies represent complex shapes; the flows present in these sections are complex and greatly affect device performance. Increasing the fidelity of the local flow fields at these interfaces delivers a more accurate representation of the device performance in vivo