Mait Harf

Automated Program Synthesis for Java Programming Language

In this paper we introduce a methodology of program synthesis for Java programming language by extending Java classes with high level specifications. The specifications are handled by a distributed synthesizer also briefly described in this paper.

Multi-pole modeling and simulation of an electro-hydraulic servo-system in an intelligent programming environment

Abstract The paper presents composing of models and simulation of an electro-hydraulic servo-system, including hydraulic servo-drive with feedback regulator, electro-hydraulic servo-valve and constant pressure feeding system with variable displacement pump. For composing mathematical models of the fluid power system multi-pole models with different oriented causalities are used. Using multi-pole models allows describe models of required complexity for each component. Using a Java based intelligent programming environment CoCoViLa as a tool, enables one graphically describe multi-pole models of the system and perform simulations in a user-friendly manner. Solving large equation systems during simulations can be avoided. Models of four-way sliding spool throttling slot pairs describe open slot and overlapped slot characteristics of various causalities. For correcting the control signal to the electro-hydraulic servo-valve a non-linear differential regulator is used. An intelligent simulation environment CoCoViLa supporting declarative programming in a high-level language and automatic program synthesis is shortly described. It is convenient to describe simulation tasks visually using visual images of multi-pole models. The designer does not need to focus on programming, but instead can use the models with the generated code. Simulations of subsystems of electro-hydraulic servo-system and the entire system are considered and simulation results are presented and discussed.

Modelling and Simulation of Fluid Power Systems in Object-Oriented Programming Environment

The paper deals with principles of computer modelling and simulation of behaviour of fluid power systems in object-oriented programming environment. The approach is based on using multi-pole models and signal-flow graphs of functional elements, that enables methodical, graphical representation of mathematical models of large and complicated chain systems. In this way we can be convinced in the correct composing of models. A high-level programming environment NUT is used as a tool for building modelling and simulation systems. Several modelling and simulation systems have been developed using approach described above. Different simulation tasks have been solved on these modelling systems. Methodology described in the paper has several advantages and novelties.Copyright

Model-based simulation of hydraulic hoses in an intelligent environment

Abstract In this paper, comprehensive mathematical models of hydraulic hoses for fluid power systems and a modelling and simulation technology based on using multi-pole models and intelligent simulation environment are proposed. Principles of composing multi-pole mathematical models for hydraulic hoses with lumped parameters having various causalities are discussed. Computing transient and frequency responses of hydraulic hoses in a visual simulation tool CoCoViLa are considered. The CoCoViLa environment is a visual programming tool, which supports declarative programming in a high-level language and automatic program synthesis. The proposed technology enables to find optimal solutions for hydraulic hoses in design and development of various fluid power systems.

A case study of combining compositional and object-oriented software development

We analyze an approach to software development where object-oriented and compositional software specifications are written in separate languages and are only loosely connected. It supports compositional design of software in a domain-specific language and automatic model-driven construction of code from classes written in Java. We justify our approach by giving examples of development of large simulation programs and services on large models. We present also an example of using our method in general purpose software development - this is bootstrapping the essential part of a software tool CoCoViLa, i.e. synthesizing CoCoViLa in CoCoViLa itself.

Modeling and Simulation of an Electro-Hydraulic Servovalve in an Intelligent Programming Environment

Composing of models and simulation of statics, steady state conditions and dynamic responses of an electro-hydraulic servovalve is considered in the paper. The observed servovalve contains an electro-mechanical transducer (as a torque motor), a nozzle-and-flapper valve and a sliding spool in sleeve with elastic position feedback from spool to flapper. For composing mathematical models of the servovalve multi-pole models of functional elements are used. For representing relations between inner variables oriented graphs are used.Results of the current work will be used in modeling and simulation of electro-hydraulic servo-systems.Copyright

Design Of A Hydraulic-Mechanical Load-Sensing System Using Object-Oriented Modelling And Simulation

This paper deals with the design of a hydraulicmechanical load-sensing system using computer modelling and simulation in an object-oriented programming environment. As initial, the scheme of a hydraulic-mechanical load-sensing system of Bosch GMbH has been taken. A modified scheme of the system is proposed. The object-oriented mathematical model of the system is composed. The approach is based on using multi-pole models and signal-flow graphs of functional elements, enabling methodical, graphical representation of mathematical models of large and complicated chain systems. In this way we can be convinced of the correct composition of models. The high-level programming environment NUT is used as a tool for modelling and simulation. A procedure of adjusting the multi-pole model is proposed. Modelling and simulation of separate objects, subsystems and the whole system are discussed. 1 HYDRAULIC-MECHANICAL LOAD-SENSING SYSTEM Fluid power systems, in which working pressure (pressure in pump output) is kept proportional to load, are called hydraulic load-sensing systems. Such systems are mainly used in mechanisms containing numerous drives to run with the purpose to save energy. The scheme of the hydraulic load-sensing system of Bosch GmbH is shown in Fig. 1, the scheme of hydraulicmechanical controller in Fig. 2 and the section of the valve block in Fig. 3. In Fig. 1, the variable displacement axial piston pump is driven by an electric motor M. Hydraulic-mechanical control of the pump volumetric flow is performed by control valve and hydraulic cylinder. The feeding chain of the hydraulic motor RVerbr contains tube RL-zu, pressure compensator RIDW, measuring valve RVW, check valve, meter-in throttle edge RSK-zu and connection elements. The output chain of the hydraulic motor RVerb contains a meter-out throttle edge RSK-r, and tube RL-ab. The device contains load-sensing pressure feedback with resistance RLS. Fig. 1 Scheme of the hydraulic–mechanical load-sensing system of Bosch GmbH. Proceedings 21st European Conference on Modelling and Simulation Ivan Zelinka, Zuzana Oplatkova, Alessandra Orsoni ©ECMS 2007 ISBN 978-0-9553018-2-7 / ISBN 978-0-9553018-3-4 (CD) The scheme of a hydraulic-mechanical controller (Fig. 2) contains a spool valve (effective area AV) with inflow and outflow slots, constant resistor (volumetric flow QDr), positioning cylinder (effective area AZ), and swash plate with spring. Fig. 2 Scheme of a hydraulic-mechanical controller. Fig. 3 Section of the valve block. The main part of the valve block (Fig. 3) is a directional valve with measuring throttle edge RVW, meter-in throttle edge RVS-zu and meter-out throttle edge RSK-r. The valve block also contains pressure compensator with throttle edge RIDW and check valve with pressure drop 0.5 bars. Examples of modelling and simulation of this loadsensing system were discussed in (Grossschmidt et al. 2006). The load-sensing system is quite complicated and contains several feedbacks. Iterations that were used in the simulation process turned out to be unstable. The resulting graphs appeared to be not smooth. To get better results we need to improve the model. The main reason of instability is that the feeding pressure of the controller was taken from the output of a variable displacement hydraulic pump. But the pressure in the pump output depends on the resistance of the whole system. Pressure drops in connecting tubes of feedback chains affect the system behaviour as well. 2 MODIFIED LOAD-SENSING SYSTEM A modified scheme of load-sensing system is proposed, in which the controller has an independent constant pressure feeding. Feedback pressures have been taken directly from the measuring valve with pressure compensator RIDVW. The scheme of modified load-sensing system is shown in Fig. 4.

The Cash-Point Service in NUT

Abstract. This paper describes how the cash-point service can be modelled and simulated using the NUT system.