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

On-line measurement using radar: A new revolution in process automation?

Strict conditions in steel production and processing complicate usage of sensors in rolling, thereby determination of strip parameters and characteristics of technological process can be either sometimes realized approximately, or it can be impossible at any process stages. The results obtained lately in the field of development of radar technics in combination with intellectual analytical methods for measured signal can lead to creation of the new prospective measurement systems that will allow for the first time to register hardly determined parameters of rolling mills with high degree of reliability and precision. It opens the new opportunities for iron and steel industry that were not used before and now can be applied both for quality improvement of rolled strip (e.g. due to minimization of length deviations) and for productivity rise (e.g. due to strip traffic stabilization). To realize these aims, Asinco GmbH together with its partners from scientific-research ce nters and production plants has developed the new processes and products described in this paper. One of such systems for strip width measurement at the entrance of pickling line is now under testing. The pilot radar device for speed measurement of slab transportation is tested on the other production site. The radar devices for quality control of rolled strip surface is in the process of development now, and the radar devices for flatness determination are included in the development plans

Zur rechnergestuetzten Approximation nichtlinearer Systeme durch Polynomsysteme

Available from TIB Hannover: RN 8583(1996,20) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Model-based force and position tracking control of an asymmetric cylinder with a digital hydraulic valve

This paper presents a model-based control solution for large inertia systems controlled by a fast digital hydraulic valve. The solution is based on model-based force control and it is shown that the cylinder chamber pressures have first order dynamics with the proper parameter selection. The robust stability is analyzed under unknown load mass, bulk modulus, and delay, and it is shown that a simple cascaded P  +  PID controller results in good control performance and robustness. The simulated results show smooth and stable response with good tracking performance despite large variations in the load mass and bulk modulus.Peer reviewe