I. Arredondo

ESS-Bilbao light-ion linear accelerator and neutron source: design and applications

The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been completed and the normal conducting section of the linac is at present under construction. The machine has been designed to be compliant with ESS specifications following the international guidelines of such project as described in Ref. [1]. The new accelerator facility in Bilbao will serve as a base for support of activities on accelerator physics carried out in Spain and southern Europe in the frame of different ongoing international collaborations. Also, a number of applications have been envisaged in the new Bilbao facility for the outgoing light ion beams as well as from fast neutrons produced by low-energy neutron-capture targets, which are briefly described.

Stability analysis and robust control design on an AMB system

This paper describes a stability analysis and a Hinfin robust control design for an electromechanical system consisting of a rotary flexible spindle hovered by active magnetic bearings (AMB), whose potential uses in the machine-tool industry have been well documented. Firstly, a complete experimental stability analysis is performed controlled by a previously designed PID controller. This is performed via the ISO 14839-3 standard, which reliability needs to probe the negligibility of some effects. Then, since the lack of robustness is concluded by the previous study, an Hinfin control design is accomplished. Moreover, the ill-conditioning of the matrices when the DGKF algorithms are solved, is avoided performing a model reduction. This is carried out by means of the symmetry properties which characterize the system and hence, facilitating the design. The better behavior of the system is probed by simulation in a complete model of the real device.

Analysis and control design of MIMO systems based on symmetry properties

In this work the design advantages derived from certain symmetry properties inherent to different class of systems are explored. In particular, some class of MIMO systems which can be separated into different and independent SISO problems, thus making easier the analysis and control design, are addressed. Also, it is shown how the symmetry properties give a direct way for open-loop identification, valid also in unstable cases, using closed-loop data. As a real-world application example, the proposed method is applied to a magnetic bearing system having the required symmetry properties.

2-DOF Controller Design for Precise Positioning a Spindle Levitated with Active Magnetic Bearings

This article describes the design of a high performance 2-DOF controller for an electromechanical system consisting of a rotary flexible spindle hovered by Active Magnetic Bearings (AMB). The purpose of such a controller is to achieve the better positioning possible of the spindle by means of a good stabilization mechanism and by counteracting the vibrations generated naturally by the rotation. The implementation of this controller is based on three main blocks, a stabilization block, a vibration minimization block and, if needed, a dynamics decoupler block between the previous ones. The stabilization controller is designed utilizing a MIMO decoupling technique. With the aim of proving its effectiveness, two different stabilization controllers (PID and H ∞ ) are presented. On the other hand, an adaptive feedforward algorithm which is in charge of the vibration minimization is implemented. In order to not feedback the vibration and, therefore, to decouple the controllers dynamics, the implementation of a variable Notch filter is discussed. It is demonstrated that this optional block can enhance or impoverish the behavior of the system depending on several factors such as resonances or rotational speed measurement. Experimental results and simulations are provided to show the effectiveness of the complete design process.

ISHN Ion Source Control System. First Steps Toward an EPICS Based ESS-Bilbao Accelerator Control System

ISHN (Ion Source Hydrogen Negative) consists of a Penning type ion source in operation at ESS-Bilbao facilities. From the control point of view, this source is representative of the first steps and decisions taken towards the general control architecture of the whole accelerator to be built. The ISHN main control system is based on a PXI architecture, under a real-time controller which is programmed using LabVIEW. This system, with additional elements, is connected to the general control system. The whole system is based on EPICS for the control network, and the modularization of the communication layers of the accelerator plays an important role in the proposed control architecture.

Active Magnetic Bearings Robust Control Design based on Symmetry Properties

This paper describes an Hinfin robust control design for an electromechanical system consisting of a rotary flexible spindle hovered by active magnetic bearings (AMB), whose potential uses in the machine-tool industry have been well documented. Symmetry properties are utilized to perform a model reduction avoiding the ill-conditioning of the matrices when Hinfin algorithms are solved and hence, facilitating the design of the controller. The better behavior of the system is probed by simulation in a complete model of a real device.

Nonlinear analysis of an AMB system using harmonic domain LTV models

Although the AMB technology has important advantages mainly due to the lack of mechanical friction, its nonlinear nature complicates the design and control of such systems. In this work, the nonlinear analysis of an AMB system, the MBC500 Rotor Dynamics from Launchpoint Technologies, is presented. This analysis is based on the harmonic domain linearization of the AMB system around a nonlinear stationary solution, leading to a LTV model for each rotating speed. The nonlinear nature of the response appears at high speeds, due to the large oscillations introduced by the shaft unbalance. Using the presented methodology, low frequency gain loss is detected when increasing the rotating speed. This phenomenon causes the instability of the system, leading to destructive crashes

Design and Performance Analysis of a Nonstandard EPICS Fast Controller

Large scientific projects present new technological challenges, such as the distributed control over a communication network. In particular, the middleware Experimental Physics and Industrial Control System (EPICS) is the most extended communication standard in particle accelerators. The integration of modern control architectures in these EPICS networks is becoming common, as for example for the PXI/PXIe and xTCA hardware alternatives. In this paper, a different integration procedure for PXI/PXIe real-time controllers from National Instruments is proposed, using LabVIEW as the design tool. This methodology is considered and its performance is analyzed by means of a set of laboratory experiments. This control architecture is proposed for achieving the implementation requirements of fast controllers, which need an important amount of computational power and signal processing capability, with a tight real-time demand. The present paper studies the advantages and drawbacks of this methodology and presents its comprehensive evaluation by means of a laboratory test bench, designed for the application of systematic tests. These tests compare the proposed fast controller performance with a similar system implemented using an standard EPICS IOC provided by the CODAC system.

Modelización, Análisis y Control de Sistemas de Cojinetes Magnéticos Activos

In this study the modeling, control design, robustness analysis and vibration active suppression procedure of a system, based on a rotor hovered by active magnetic levitation, are presented. Firstly, the model obtaining and its main characteristics are described. Utilizing this model and taking advantage of its symmetry properties, a stabilizing controller is designed. Then, it is tuned by means of a robustness study, according to the standard ISO 14839-3. Finally, a reduction of the vibrations produced in rotation is performed, using adaptive control. The designed controller has been experimentally implemented successfully.

Modelling of a flexible rotor maglev system

This paper describes the modelling process of a mechanical system consisting of a rotary flexible spindle hovered by active magnetic bearings (AMB), whose potential uses in the machine-tool industry have been well documented. The modelling takes into account the three main behavioural characteristics of such magnetically-levitated rotor: the rigid dynamics, the flexible dynamics and the rotating unbalanced motion. Using this model, a stabilizing controller has been successfully designed for the system and a complete experimental analysis of its performance is carried out. Also, the predictions of the model are compared with the actual measured experimental results on a laboratory set-up. Finally, a brief study about some non-linear behaviour observed m the system and its effect over the system stability at the critical speed is included