Accelerator Control System Research Articles

Transient acceleration waveform replication of electro-hydraulic systems using convex combined adaptive controller with input shaping technique

Electro-hydraulic systems are extensively utilized to generate desired acceleration waveforms to provide a vibration environment for testing the performance and reliability of objects in various industrial applications. However, as electro-hydraulic systems are often affected by some inevitable drawbacks resulted from hydraulic nonlinearities, unwanted dynamic variations and disturbances, the generated acceleration waveform is generally far behind the expectation. In this paper, a convex combined adaptive controller with input shaping technique is proposed for enhancing the transient acceleration waveform replication accuracy of electro-hydraulic systems. The proposed controller is comprised of a three variable controller at the bottom level, an input shaping technique controller at the middle level, and a convex combined adaptive controller at the upper level. The three variable controller is firstly utilized for the establishment of a fundamental closed-loop acceleration control system, and then the input shaping technique controller is constructed by introducing an offline designed inverse prefilter utilizing the multi-innovation recursive least squares algorithm and the zero magnitude error tracking algorithm. The convex combined adaptive controller at the upper level is comprised of two individual adaptive filters with high and low step sizes, which provides the merits of fast convergence rate and high tracking accuracy, and it is further exploited to address for system’s dynamic variations, model uncertainties and unexpected perturbations. Comparative experiments of the proposed controller with a manually generated random waveform and a recorded earthquake waveform as the testing inputs are conducted on a typical electro-hydraulic test bench, and the corresponding results demonstrate the feasibility and superiority of the proposed controller in improving the transient acceleration waveform replication performance of electro-hydraulic systems.

Next generation Linux Applications Gateway for CERN accelerator control systems

Next generation Linux Applications Gateway for CERN accelerator control systems

Accuracy and reliability of a commercial treatment planning system in nontarget regions in modern prostate radiotherapy.

The currently available treatment planning systems (TPSs) are neither designed nor intended for accurate dose calculations in nontarget regions. The aim of this work is to quantify the accuracy and reliability of nontarget doses calculated by a commercially available TPS. Nontarget doses calculated by the collapsed cone (CC) (v5.2) algorithm implemented in the RayStation (v6) TPS were compared to measured values. Different scenarios were investigated, from simple static fields to intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) treatment plans. Deviations and confidence limits (CLs) were calculated between results of calculations and measurements-applying both local (δ) and global (Δ) normalization-for various points of interest (POIs). Results were based on a single-institution experience for one clinical test case (prostate) and evaluated against internationally accepted criteria. Overall, the TPS underestimated the nontarget dose by an average of -17.7%±25.3% for IMRT. Quantitatively similar results were obtained for VMAT (-17.6%±21.2%). POIs receiving < 5% of the prescription dose were significantly underestimated by the TPS (p-value<0.05 for both IMRT and VMAT). Dose calculation accuracy was also determined by the contribution of secondary radiation, with measured doses for out-of-field POIs being significantly different from calculated values (p-value<0.01 for both IMRT and VMAT). Although the CLδ in nontarget regions failed the proposed tolerance criteria (40%) for both IMRT (68.8%) and VMAT (52.6%), the CLΔ was within the tolerance limit (4%) for both treatment techniques (1.9% for IMRT and 1.3% for VMAT). No action levels (7%) were exceeded. Based on the currently available benchmarks our TPS is considered acceptable for clinical use, although the dose in some POIs was poorly predicted by the CC algorithm. Some areas were pointed out where TPSs and linear accelerator control systems can be improved.

Fabrication of Automatic Acceleration Control System in Vehicles

In General Indian Road Transporting Conditions is concerned, mischance’s are turning into an everyday cause an endeavor has been made in this venture to diminish such setbacks. In our venture a fast sign is given and programmed braking is connected by removing the fuel supply to the motor when the setup speed is Overpassed. Our Objective is to plan a programmed increasing speed control in activity flag/Sign Board. The setup of the model does not permit abusing the activity rules. This model comprises of an engine with rack and pinion course of action, point of confinement switches and the quickening agent. This venture is basically created to maintain a strategic distance from mishaps because of fast vehicles and furthermore to empower general society to cross the street with no threat from rapid vehicles. Normally the drivers drive the vehicles at rapid Speed without considering general society in speed constrained ranges as well. Despite the fact that the activity controls them we can't accomplish the full reaction from them. Likewise it is impractical to screen those regions at unsurpassed to control their speed. File Terms-Automatic Acceleration, High speed Indication.&#x0D;

Load-side acceleration control based on load-side velocity disturbance observer for geared actuator

This paper focuses on load-side acceleration control of geared actuator that is modeled as a two-inertia system for industrial/non-industrial robot applications. This paper uses a load-side acceleration sensor that is capable of acquiring direct current components. Conventional load-side acceleration control has some high-frequency components due to the noise effect of an acceleration sensor due to the use of two observers that combines acceleration sensor. This paper proposes a load-side acceleration control system based on a load-side velocity disturbance observer and motor-side velocity controller for a geared actuator of an industrial robot with mechanical resonance. The proposed approach employs a motor-side velocity controller and a load-side velocity disturbance observer, which are employed to simplify the plant system, and compensate for the velocity disturbance on the load side, respectively. This approach has a structure in that the noise effect of the acceleration sensor is small compared with the conventional approach. The effectiveness of the proposed load-side acceleration controller is verified via theoretical analysis, numerical simulations, and practical experiments.

Real-Time Regulation of Beam-Based Feedback: Implementing an FPGA Solution for a Continuous Wave Linear Accelerator.

Control applications targeting fast industrial processes rely on real-time feasible implementations. One of such applications is the stabilization of an electron bunch arrival time in the context of a linear accelerator. In the past, only the electric field accelerating the electron bunches was actively controlled in order to implicitly stabilize the accelerated electron beam. Nowadays, beam properties are specifically measured at a target position and then stabilized by a dedicated feedback loop acting on the accelerating structures. This dedicated loop is usually referred to as a beam-based feedback (BBF). Following this, the control system of the electron linear accelerator for beams with high brilliance and low emittance (ELBE) is planned to be upgraded by the BBF, and the problem of implementing a designed control algorithm becomes highly relevant. In this work, we propose a real-time feasible implementation of a high-order regulator based on a field-programmable gate array (FPGA). By presenting simulation and synthesis results made in hardware description language (HDL) VHDL, we show that the proposed digital solution is fast enough to cover the bunch repetition rates frequently used at ELBE, such as 100 . Finally, we verify the implementation by using a dedicated FPGA testbench.

A Deep Deterministic Policy Gradient Learning Approach to Missile Autopilot Design

In this paper a Deep Reinforcement Learning algorithm, known as Deep Deterministic Policy Gradient (DDPG), is applied to the problem of designing a missile lateral acceleration control system. To this aim, the autopilot control problem is recast in the Reinforcement Learning framework, where the environment consists of a 2-Degrees-of-Freedom nonlinear model of the missile&#x2019;s longitudinal dynamics, while the agent training procedure is carried out on a linearized version of the model. In particular, we show how to account not only for the stabilization of the longitudinal dynamic, but also for the main performance indexes (settling-time, undershoot, steady-state error, etc.) in the DDPG reward function. The effectiveness of the proposed DDPG-based missile autopilot is assessed through extensive numerical simulations, carried out on both the linearized and the fully nonlinear dynamics by considering different flight conditions and uncertainty in the aerodynamic coefficients, and its performance is compared against two model-based control strategies in order to check the capability of the proposed data-driven approach to achieve prescribed closed-loop response in a completely model-free fashion.

Understanding the control characteristics of electric vertical take-off and landing (eVTOL) aircraft for urban air mobility

The aim of the present paper is to present an understanding of the control characteristics for representative eVTOL (Electric Vertical Takeoff and Landing) quadcopters having the same properties of interest as the eVTOL configurations developed presently in Urban Air Mobility. In this context, the paper concentrates on eVTOL quadcopters with pure rpm control, pure propeller pitch control and both rpm and propeller pitch control. Dynamic effects of electric motors can potentially have significant effects on the flight characteristics of these vehicles. The paper will demonstrate for a pitch manoeuvre that while varying purely the rpm of the rotors results in a system that behaves as an acceleration-control system, varying purely the propeller pitch corresponds more to a velocity-control system. The rotor pitch control is more sensitive to the coupling rotor-motor and its transients dynamics. Varying both the rpm and the rotor pitch for controlling the pitch manoeuvre is the best option as this brings the system more towards velocity-control behaviour and dampens the transients due to the motor dynamics.

Developing Robust Digital Twins and Reinforcement Learning for Accelerator Control Systems at the Fermilab Booster

We describe the offline machine learning (ML) development for an effort to precisely regulate the Gradient Magnet Power Supply (GMPS) at the Fermilab Booster accelerator complex via a Field-Programmable Gate Array (FPGA). As part of this effort, we created a digital twin of the Booster-GMPS control system by training a Long Short-Term Memory (LSTM) to capture its full dynamics. We outline the path we took to carefully validate our digital twin before deploying it as a reinforcement learning (RL) environment. Additionally, we demonstrate the use of a Deep Q-Network (DQN) policy model with the capability to regulate the GMPS against realistic time-varying perturbations.

RBS Channeling MATLAB Application for Automated Measurement Control and Evaluation for 6MV Tandetron Accelerator

Rutherford backscattering spectrometry (RBS) in channeling regimes (RBS/C), as an ion beam analysis method performed on a Tandetron 6MV accelerator, generally gives precise information about the structure of crystalline samples by combining RBS signals in the random and aligned configurations. This paper presents details about the design and implementation of tailored RBS/C measurements (coarse and fine) and data evaluation application developed in MATLAB for in situ accelerator control system ARGUS, delivered by High Voltage Engineering Europa BV (HVEE). Additionally, we examined two different ways of stepping during the measurement to reduce the possible inaccuracies related with goniometer’s backslash affecting the evaluation of spectra. Verification experiment was carried out using a 2-MeV 4He+-beam directed on a Si (100) substrate. The channeling effect is seen as channeling dips of a lower signal in an otherwise rather homogeneous plane. Implemented application significantly facilitates the RBS/C measurement and analysis of the experiments, and also extends the ion beam analysis portfolio of Advanced Technologies Research Institute. Finally, software is ready-to-use for any Tandetron based ion beam facility with the ARGUS software for accelerator control.

Research of evaluation method of auxiliary frequency modulation in gas turbine unit

In this paper, according to the mechanical structure of the gas turbine set and the process of primary frequency modulation, the models including the speed regulating system, combustion chamber, temperature control system, torque control system, acceleration control system and synchronous generator are established. Bidirectional DC/DC converter and inverter model are established according to the circuit structure and corresponding control strategy. According to the primary frequency modulation process of the gas turbine, the control strategy of the energy storage system participating in the primary frequency modulation is set. The energy storage system uses the traditional droop control strategy and combines the primary frequency modulation process of gas turbine to improve the frequency modulation performance of gas turbine and offshore platform microgrid. Finally, PSCAD transient simulation software is used to build offshore platform and a multi-platform interconnection micro-grid model, results of the simulation show high performance of the designed microgrid.

Improvement of the System of Diagnostics of Metal Structures and Mechanisms of Foundry Cranes

Periodic assessment of the technical condition of mechanisms and metal structures of foundry cranes is insufficient to ensure the reliability of the technogenic system of metallurgical production with long operating resources. Overviewing a crane as a set of rateresource elements with different recovery periods and regular control make it possible to set a range of optional and functional diagnostic parameters with regular inspection and constant control of technical condition of foundry cranes. The foundry crane is considered as an interaction of subsystems for which the operating conditions, characteristic damages and defects are determined. For diagnostics, the application of the following methods is considered: visual, visual-optical, vibration, thermal, non-destructive testing methods in the general structure of measures to maintain and restore the working condition of metallurgical cranes. Control and assessment of the condition of hawser, metal structures, lifting and movement mechanisms, automation systems are considered. The duplication of the strain monitoring system is carried out by the acceleration control system of metal structures – which allows to estimate the loads impact on the metal structure by the value of accelerations, which serves as the basis for the load cycle counter. The use of organoleptic methods, the installation of fixed systems and methods for periodic monitoring using portable instrumentation and multichannel systems, such as complex UMS-16 in conjunction with the SAFE PLANT allows to provide maintenance service information, prevents injuries, developing at different speeds.

Policy gradient methods for free-electron laser and terahertz source optimization and stabilization at the FERMI free-electron laser at Elettra

In this article we report on the application of a model-free reinforcement learning method to the optimization of accelerator systems. We simplify a policy gradient algorithm to accelerator control from sophisticated algorithms that have recently been demonstrated to solve complex dynamic problems. After outlining a theoretical basis for the functioning of the algorithm, we explore the small hyperparameter space to develop intuition about said parameters using a simple number-guess environment. Finally, we demonstrate the algorithm optimizing both a free-electron laser and an accelerator-based terahertz source in-situ. The algorithm is applied to different accelerator control systems and optimizes the desired signals in a few hundred steps without any domain knowledge using up to five control parameters. In addition, the algorithm shows modest tolerance to accelerator fault conditions without any special preparation for such conditions.

The accelerator control system of CSNS

The China Spallation Neutron Source is an accelerator-based user facility for neutron, proton, muon applications and so on. The designed proton beam power is 100 kW for the first phase. Overall, the scope of accelerator control system covers four parts, the global systems, the device layer local controls and remote controls, the high-level applications and services and the integration of conventional facilities. The principle guideline is to adopt as many as possible matured technologies and commercial products in the design and implementation. The control system is based on Experimental Physics and Industrial Control System. VME64x bus is chosen for timing system and fast protection system. PLCs and embedded industrial computers are used in the device layer slow controls. Control System Studio is adopted as the high-level applications. Blade server-based virtualization platform is deployed for the computer system. The accelerator control system was completed in September 2017 and then transited to routine operations. The design, implementation and operation of the accelerator control system are described in this paper.

Physics issues of the diffraction-limited storage ring light source

<p indent=0mm>The synchrotron radiation light source based on electron storage ring is the most widely used high-performance X-ray source in the field of basic scientific research in the 20th century, and has undergone three generations of development. One important direction of the new generation light source, i.e., the fourth generation light source, is the so-called diffraction-limited storage ring (DLSR) light source. DLSR, with ultra-high average brightness, high repetition frequency, multi-user, high stability, complementary to the free electron laser (FEL), has a great development in recent decades. By adopting lattice design based on compact multi-bend achromats (MBAs), DLSR allows to achieve one or two orders of magnitude lower emittance approaching the diffraction limit of X-rays, and much higher brightness and coherence than available in the third generation light source, while inheriting the high brightness, multi-user and high stability advantages of existing ring light sources. In this paper, the progress made in the last few decades in physics design and optimization of the DLSR, especially on the ultralow-emittance lattice and injection schemes, will be overviewed. To achieve an ultralow emittance, lattice structures of standard MBA and hybrid MBA, and novel magnets of high-gradient quadrupole, antibend, longitudinal gradient dipole and complex bend, have been proposed. To obtain optimized beam dynamics in a DLSR, theoretical and numerical methods have been developed to date. Due to the fact that the nonlinearities are extremely high in a DLSR and the nonlinear dynamics is greatly coupled with the linear optics, the most effective and most commonly used way is global and stochastic optimization of the ring performance evaluated by numerical tracking. To deal with the challenges of injecting to a DLSR with small dynamic acceptance, different injection schemes, such as, pulsed multipole injection, on-axis swap-out injection and on-axis longitudinal injection, have been proposed. Collective effects, especially the intra beam scattering and the Touschek effects, become significant as emittance decreases, requiring methods of bunch lengthening and transverse feedback to ensure the stability of the particle motion at a high beam current. Besides, a few developing topics in DLSR physics will be discussed. Machine learning, the method of transferring disorder data into useful information, is an important branch of artificial intelligence, and has been used in accelerator control system and beam commissioning. This method would be very useful and helpful in the design and optimization, initial commissioning and daily operation of a DLSR. A rational combination of machine learning and multi-objective optimization algorithm, like multi-objective genetic algorithm and multi-objective particle swarm algorithm, can effectively improve the optimization performance, and has been successfully applied in nonlinear optimization of light sources. In addition, improving the performance of synchrotron radiation by combining the beam physics of DLSR and the principle of FEL is one developing research topic which might be able to provide base for further development of the DLSR. Combined with bypass and transverse gradient undulator, high gain FEL could be achieved in the storage ring. Besides, double ring light source, divided into two loops, the inner ring is DLSR, and the other is FEL with more long straight sections, was proposed to improve the utilization rate of the beams.

Acceleration and spin control system for in-car crib with joint application of regular and inverted pendulum mechanisms

Acceleration and spin control system for in-car crib with joint application of regular and inverted pendulum mechanisms

The design of PACS (Physics-oriented Accelerator Control System) and its implementation in a heavy ion accelerator facility

As many diverse accelerator facilities are designed, constructed and operated by IMP (Institute of Modern Physics, Chinese Academy of Sciences), the existing physics control system cannot cover all requirements of these facilities. In order to save the construction time, improve the commissioning efficiency, simplify the operation and reach higher beam intensity and better beam quality, a new physics control system, PACS (Physics-oriented Accelerator Control System), is proposed, designed and implemented in the IMP. With the control layer in three layers, i.e. application layer, physics layer and control layer, the PACS is protocol neutral and can be deployed to all accelerator facilities in the IMP without massive reprogramming. The physics layer encapsulates all physics control processes, including device-level physics and system-level physics, into highly usable interfaces, which makes the development of the application layer and the customized applications simpler, more robust and efficient. Due to the OOP (Object-oriented Programming) technology used in this layer and specific designs, the PACS is highly scalable and can keep pace with the rapidly changing hardware and software. As the application layer is built upon the physics layer interfaces, no matter what is updated in the physics layer, the applications remain unchanged. Many new physics control processes can be tested and implemented in the physics layer by the developers or the users without influencing the operation of these facilities. Now, a version of PACS for miniature facilities is implemented and tested in the CSR, a heavy ion accelerator facility for scientific research in the IMP. It meets the expected goals and provides a solid base for following versions. In the future, the PACS will become a general-purpose physics control system for all heavy ion accelerator facilities.

RF System of Linear Accelerator for Natural Rubber Research

The natural rubber research is ongoing project at the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The project aims to use electron beam irradiation for high quality vulcanization process for natural rubber. The main accelerator system consists of a DC thermionic electron gun, 5-cell linear accelerator structure, control system, RF system and electron beam irradiation system. This accelerator system aims to generate adjustable electron beam energy range from 0.5 to 4.0 MeV with pulse current of 10 – 100 mA and pulse repetition rate of 20 – 200 Hz. The 4 MeV electron beam with current of 100 mA produced at pulse repetition rate of 200Hz is expected to achieve the maximum absorbed dose of 320 Gy. The control system is designed and built in-house to fit the accelerator system requirement. The RF system consists of Pulse Forming Network (PFN), trigger board and thyratron switch, pulse transformer and pulse magnetron. This RF system can achieve RF power of 0.9 to 2.0 MW with pulse width of 4 μs. The pulse repetition rate can be varied from 20 to 200 Hz to control RF average power. The performance of RF system as well as the results of RF commissioning will be present and discussed.

The Design of LEAF Motion Control System

The scientific installation project (HIAF)will be undertaken by the Institute of Modern Physics of the Chinese Academy of Sciences. LEAF (Low Energy intense-highly-charged Accelerator Facility) is a pre-research project for the future large-scale scientific installation about HIAF. It was received the support of the National Major Instrument Equipment R&D Fund. In the accelerator control system, motion control plays an important role. Motion control is a branch of automation. It mainly uses servos and motors to control the position or speed of the machine. The motion control system designed in this paper is mainly used to control the gas in and out, slits motion control, beam diagnostics and other equipment. It mainly studies the hardware architecture of the motion control system, the application of EPICS in the motion control system, the HMI design of the CSS and the test of the motion control system.

Embedded EPICS Control System of Hight Voltage Power Supply for Extraction Deflector on HIRFL-CSR

Control system of HIRFL-CSR accelerator is now upgrading to new architecture based on Experimental Physics and Industrial Control System (EPICS), a control sub-system of High Voltage (HV) for slow extraction on CSRm must be redesigned with the new architecture. The hardware of the new system based on a high-performance FPGA controller. Researched on embedded EPICS technology and implemented core function of the sub-system based on the technology. This paper describes the design and implementation of the new control system.