Pressure compensator control – a novel independent metering architecture

This contribution presents an operating strategy for a novel valve structure for mobile machines’ working hydraulics which combines the flexibility and energetic benefits of individual metering with the functionality of common primary pressure compensation (IPC). The aim is to set up a system that uses a minimal amount of sensors and simple control algorithms. A control strategy theoretically described in /1/ is modified to facilitate the practical implementation on a mini excavator implement as a test rig. This test rig consists only of components that are currently available off-the-shelf to show that it is possible to develop an individual metering system under these economic restrictions. The novel is more energy efficient than common flow sharing systems but provides the same functionality. The control algorithm is experimentally evaluated in terms of functionality and energy consumption. Simulations show potential for further improvements

Hydrogen-methane fuel control systems for turbojet engines

Design, development, and test of a fuel conditioning and control system utilizing liquid methane (natural gas) and liquid hydrogen fuels for operation of a J85 jet engine were performed. The experimental program evaluated the stability and response of an engine fuel control employing liquid pumping of cryogenic fuels, gasification of the fuels at supercritical pressure, and gaseous metering and control. Acceptably stable and responsive control of the engine was demonstrated throughout the sea level power range for liquid gas fuel and up to 88 percent engine speed using liquid hydrogen fuel

CONTROL SYSTEM FOR VARIABLE-ORIFICE MECHATRONIC SPRAY NOZZLE FOR REGULATION OF APPLICATION RATE AND DROPLET SIZE SPECTRA

Traditional fixed-orifice spray nozzles are selected for flow rate and droplet spectra required for a given pesticide application. Although limited variation in flow can be achieved by adjusting system pressure, this can adversely affect spray quality. Other nozzle configurations, such as Pulse Width Modulated (PWM) nozzles or passive variable-orifice designs, are intended to maintain consistent droplet size and spray pattern as flow rate is changed but those too have limitations. A variable-orifice nozzle modified by Luck (2012) can span multiple droplet spectra and offers independent control of flow and droplet size; however, an advanced control system must be developed to make it practical for field use. The primary goal of this research was to develop such control logic by managing four system variables: flow rate, pressure, droplet size, and effective orifice size. A five-nozzle spray system was built as a testbed to develop and evaluate the control method which automatically targeted desired droplet spectra and flow rate. Performance characteristics of five sizes of variable-orifice nozzles were evaluated which showed that two nozzles, spanning fine to very coarse droplet spectra, could replace four of the five nozzles. Validation tests confirmed the control method could independently vary flow rate and droplet size. Droplet volume mean diameter was within ±10% of desired size for all operating points. Actual flow rate was within ±10% of desired flow at nearly all operating points above 207 kPa. Optimization of the control method showed promise to reduce flow error to less than ±10% across the entire operating envelope but future work remains to fully implement and validate this in the control system. Although the control method was developed with a modified variable-orifice nozzle, literature implies there is potential for it to be applied to PWM nozzles. This adaptable control method provides a foundation for development of site-specific droplet size control, weather-based droplet size control, and it is well suited for robotic and autonomous spray systems. Advisor: Joe Luc

Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

Mathematical based control method and performance analysis of a novel hydromechatronics driving system Micro-Independent Metering

This paper aims to investigate the performance of a hydraulic actuator controlled by the novel system micro-independent metering (MIM). This analysis has been performed by comparing the models of two systems which are the traditional independent metering, that depends on poppet valve, and the new hydro-mechatronics system micro-independent metering, that relies on a stepped rotary flow control valve. In general, independent metering is a hydraulic control system which guarantees a separation between the meter-in and the meter-out of the hydraulic actuator. A Valvistor valve, a special type of Poppet valves, was developed to be embedded into the independent metering (IM) system. This valve has controllability and stability shortcomings which prevent the system from spreading in the industrial applications. The Valvistor valve performance is highly affected by the fluid disturbances because the fluid is considered as a part of its control elements. A stepped rotary flow control valve has been developed to control hydraulic flow rate. The valve composed of a rotary orifice attached to a stepper motor. Using this valve instead of the traditional poppet type has led to a new configuration, that is termed by micro-independent metering. This form improves the hydraulic cylinder velocity performance by rejecting the fluid disturbances effect on the control circuit

A review of electrohydraulic independent metering technology

The subject of this paper is the review of advanced technology used in hydraulic systems. The technology in question is termed Independent Metering (IM); this is used in hydraulically driven mobile machinery, such as agricultural, construction, municipal, and forestry vehicles. The idea behind the concept is to modify the connection between the actuator, which could be a cylinder or a motor, and a flow control valve. Traditionally, spool hydraulic valves were used to control the fluid flow into and out of hydraulic actuators. This keeps the meter-in and the meter-out of the actuator mechanically connected due to the construction of these valves. This connection makes the control system blind to pressure changes in one of the hydraulic chambers in the actuator. This, in turn, reduces the overall system controllability. It also increases energy losses, especially under an overrunning load. These two main weaknesses led researchers to break this mechanical connection and get into a new technology with different characteristics. The proposed technology was called Independent Metering. New and more complex control techniques can now be applied to the hydraulic systems using this technology that were not possible before or could be applied to more conventional servo design. This paper reviews Independent Metering (IM) and the technologies used or developed in this field to date. The paper reviews the state of art hydraulic technologies and indicates the links between them and IM. It also reviews the different types of hydraulic valves used when implementing IM. This review also discusses some control algorithms, IM layouts, IM challenges, and identifies where further improvements may be achieved

A dynamic model and performance analysis of a stepped rotary flow control valve

The hydraulic independent metering (IM) is an advanced actuator driving technique that allows the implementation of advanced control algorithms or methods. The main concept of IM is to control hydraulic actuators ports, which are the meterin and meter-out, separately. In this paper, a novel stepped rotary type valve has been developed for embedding in hydraulic independent metering systems, instead of conventional types such as poppet and spool. The insertion leads to developing different and novel control techniques, which require a software in loop and hardware in loop simulation of the proposed system. The paper explores the dynamic representation of this valve and defines its own performance limitations. This includes the development of a linear model comprising its two main sub-parts which are the stepper motor and the rotary orifice. Consequently, the linear timeinvariant methods are used to explore the performance of the valve by considering the effect of different parameters namely the pressure drop, friction coefficient, damping coefficient and bristle coefficient

Development of dielectric spectroscopic sensor for contaminant detection in a hydraulic fluid and a compressed air stream

A change in a fluid’s dielectric properties can be investigated using dielectric spectroscopy to gain valuable insight into the changing condition of the fluid. A dielectric spectroscopic sensor was developed using a cylindrical capacitive sensing unit with the fluid as the dielectric media. The sensor was used to estimate or detect contaminants in a hydraulic fluid and a compressed air stream. Tests were performed with a hydraulic fluid in which the dielectric sensor’s performance was evaluated in detecting iron powder and ISO medium test dust particles as contaminants in the fluid. Using iron powder as contaminants, two tests were performed with central electrodes of diameters 6.35 mm and 17.7 mm inch placed inside the capacitive dielectric sensor. The results from partial least squares (PLS) regression showed that the root mean square error of calibration (RMSEC) and the root mean square error of cross-validation (RMSECV) for a 6.35 mm (0.25-inch) diameter central electrode were 1.1 and 1.39 of adjusted ISO cleanliness code respectively. For a 17.7 mm (0.70-inch) diameter central electrode, the RMSEC and RMSECV values were 0.62 and 0.83 of adjusted ISO cleanliness code, respectively. Similarly, a test was performed using ISO test dust particles as contaminants with a central electrode of 17.7 mm diameter. The RMSEC and RMSECV values from the model for ISO test dust were 1.29 and 1.48 of adjusted ISO cleanliness code, respectively. Tests were also conducted to investigate the efficacy of dielectric spectroscopy in detecting water and oil droplets in a compressed air stream. Spray nozzles were used to produce fine droplets of deionized water and light lubricant oil. Multivariate statistical techniques, principal component analysis (PCA) and linear discriminant analysis (LDA), were used to develop statistical classifiers, which determined the performance of dielectric spectroscopic sensor in differentiating the dry compressed air from an air stream with entrained liquid droplets. Through model calibration and cross-validation, the classifiers were able to separate the two cases without any errors, validating the dielectric sensor’s ability to detect of liquid droplets in an air stream

Smart Urban Water Networks

This book presents the paper form of the Special Issue (SI) on Smart Urban Water Networks. The number and topics of the papers in the SI confirm the growing interest of operators and researchers for the new paradigm of smart networks, as part of the more general smart city. The SI showed that digital information and communication technology (ICT), with the implementation of smart meters and other digital devices, can significantly improve the modelling and the management of urban water networks, contributing to a radical transformation of the traditional paradigm of water utilities. The paper collection in this SI includes different crucial topics such as the reliability, resilience, and performance of water networks, innovative demand management, and the novel challenge of real-time control and operation, along with their implications for cyber-security. The SI collected fourteen papers that provide a wide perspective of solutions, trends, and challenges in the contest of smart urban water networks. Some solutions have already been implemented in pilot sites (i.e., for water network partitioning, cyber-security, and water demand disaggregation and forecasting), while further investigations are required for other methods, e.g., the data-driven approaches for real time control. In all cases, a new deal between academia, industry, and governments must be embraced to start the new era of smart urban water systems

Desenvolvimento de um sistema automatizado para ensaios mecânicos

Nowadays, predict or characterize material's behaviour are arduous tasks which involve performing repetitive tests using different testing machines and sensors (internal, such as load cells, and externals, such as cameras that measure deformations). When performed manually, they result in inaccurate data, due to the repeatability of the process. However, these handling specimen tasks could be performed automatically using traditional robotic manipulators, and creating systems based on automatic mechanical testing. Consequently, the precision of the testing results increases, as well as the automatism of the processes and the test's throughput. Some commercial products are already available on the market, but these options are offered in complete systems and cannot adapt themselves to existing equipment or retrofit systems. In this work, it is created a communication infrastructure between the equipment to be included in the automatic system designed. The whole process is managing the interface communication between devices and, consequently, composing the automatic material testing routine. This requires implementing several changes in the testing machine selected aiming to increase its degree of automation and, consequently, allow further integration in the fully automatic testing procedure. Additionally, a visual perception system is created using a specimen tray randomly positioned on a setup, which includes a camera and robotic manipulator that is automatically operating the traditional specimen handling of testing. The calibration methods are accomplished using ROS framework and the final system achieved operates in automatic mode, handling specimens from the tray prototype (designed for this work) to a fixed position previously taught to the manipulator, which represents the exact feeding position in machine tests.Atualmente, prever ou caracterizar o comportamento dos materiais é uma tarefa demasiado laboriosa que envolve a realização de muitos testes repetitivos utilizando diferentes tipos de máquinas de ensaio, sensores internos (células de carga para medir forças) e externos (câmaras que medem deformações). Estes ensaios, quando executados manualmente por um operador, originam erros de imprecisão devido á repetibilidade do processo. No entanto, estas tarefas podem ser adaptadas a recursos automáticos, tirando partido da fiabilidade dos manipuladores robóticos e, aumentando assim, a precisão e quantidade de ensaios realizados no mesmo espaço de tempo. Algumas soluções comerciais já existem no mercado, porém, estas são oferecidas de forma integral que não permitem facilmente a integração de uma nova estacão (equipamento) ou o uso de uma máquina de ensaios standard mais antiga. Neste trabalho é criada uma estrutura de comunicação entre os equipamentos que permite a interface e, consequentemente, a reprodução automática de um sistema para ensaios mecânicos numa máquina tradicional de carregamento uniaxial. Para tal, um conjunto de alterações numa máquina de ensaios é sugerido visando aumentar o seu grau de automação e, consequentemente, contribuindo para a integração num sistema de ensaios totalmente automático. Adicionalmente, é criado um sistema de perceção visual (com as devidas calibrações em ROS) capaz proceder á manipulação de provetes a partir de um tabuleiro (posicionado aleatoriamente no espaço) e cujas manobras são operadas por um manipulador robótico e respetiva câmara instalados. Como resultado, o sistema executa o manuseamento automático de provetes para uma posição fixa que representa o local de abastecimento das máquinas de ensaios.Mestrado em Engenharia de Automação Industria