| Paper | Title | Page |
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| S12FC01 | Feedback – Closing the Loop Digitall | 408 |
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Many feedback and feedforward systems are now using microprocessors within the loop. We describe the wide range of possibilities and problems that arise. We also propose some ideas for analysis and testing, including examples of motion control in the Flying Wire systems in Main Ring and Tevatron and Low Level RF control now being built for the Fermilab Linac upgrade. The standard techniques used to design and analyze analog feedback systems can also be applied to digital systems. It is desirable to consider frequency response, maximum tolerable error, and stability questions for systems controlled by processors. In modern digital systems a considerable amount of software not only replaces analog circuit functions but also allows additional features to be built into the system.
Operated by Universities Research Association for the Department of Energy. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC01 | |
| About • | Received ※ 11 November 1991 — Accepted ※ 20 November 1991 — Issued ※ 04 December 1992 | |
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| S12FC02 | Generalized Fast Feedback System in the SLC | 414 |
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Funding: Work supported by Department of Energy contract DE-AC03-76SF00515. A generalized fast feedback system has been developed to stabilize beams at various locations in the SLC. The system is designed to perform measurements and change actuator settings to control beam states such as position, angle and energy on a pulse to pulse basis. The software design is based on the state space formalism of digital control theory. The system is database-driven, facilitating the addition of new loops without requiring additional software. A communications system, KISNet, provides fast communications links between microprocessors for feedback loops which involve multiple micros. Feedback loops have been installed in seventeen locations throughout the SLC and have proven to be invaluable in stabilizing the machine. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC02 | |
| About • | Received ※ 10 October 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC03 | Smart Machine Protection System | 420 |
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Funding: Work supported by Department of Energy contract DE-AC03-76SF00515. A Machine Protection System implemented on the SLC automatically controls the beam repetition rates in the accelerator so that radiation or temperature faults slow the repetition rate to bring the fault within tolerance without shutting down the machine. This process allows the accelerator to aid in the fault diagnostic process, and the protection system automatically restores the beams back to normal rates when the fault is diagnosed and corrected. The user interface includes facilities to monitor the performance of the system, and track rate limits, faults, and recoveries. There is an edit facility to define the devices to be included in the protection system, along with their set points, limits, and trip points. This set point and limit data is downloaded into the CAMAC modules, and the configuration data is compiled into a logical decision tree for the 68030 processor. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC03 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC04 | Feedback Systems for Local Control of Race Track Microtron RF Accelerating Sections | 424 |
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| In order to obtain an electron beam with an excellent energy resolution and stable characteristics, a tight control of the amplitude and phase of the field in all rf accelerating sections is required. The high rf power level, dissipated in the accelerating section (AS), together with temperature dependence of the AS resonance frequency caused the creation of the original control system of resonance frequency. Amplitude, phase and resonance frequency local feedback control system have been designed. All systems are computer controlled analogue single loops. The control loops guarantee stable, repeatable amplitudes (10-1 relative error), phases (± 0.5°) of the rf fields in AS, resonance frequency of AS (± 2 kHz) and have optimal bandwidth. A model of feedback loops has been developed that agrees well with measurements. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC04 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC05 | PLS Beam Position Measurement and Feedback System | 427 |
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Funding: Work supported by Pohang Iron & Steel Co., Ltd. (POSCO) and Ministry of Science and Technology (MOST), Government of Republic of Korea. A real-time orbit correction system is proposed for the stabilization of beam orbit and photon beam positions in Pohang Light Source. PLS beam position monitor system is designed to be VMEbus compatible to fit the real-time digital orbit feedback system. A VMEbus based subsystem control computer, Mil-1553B communication network and 12 BPM/PS machine interface units constitute digital part of the feedback system. With the super-stable PLS correction power supply, power line frequency noise is almost filtered out and the dominant of beam orbit fluctuations are expected to appear below 15 Hz. DSP board in SCC for the computation and using an appropriate compensation circuit for the phase delay by the vacuum chamber, PLS real-time orbit correction system is realizable without changing the basic structure of PLS computer control system. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC05 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC06 | A Position Feedback Control System for the Test Facility of JLC | 431 |
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| In order to develop an alignment system for the Japan Linear Collider(JLC), we have constructed a test facility to study the position control system with multiple degrees of freedom for massive load. Noticeable points of the test facility are as follows. (1) Feedback fine alignment system which consists of piezoelectric actuators and laser interferometers. (2) High-speed controller using VME modules. (3) Level positioner driven by stepping motors. The controller can easily be connected with other computers by using RS-232C or Ethernet, so that their states such as positions can be monitored by another computer system. This facility achieves the alignment of multi-degrees of freedom with the accuracy of the order of submicron. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC06 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC07 | RF Control System of the HIMAC Synchrotron | 434 |
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| HIMAC is a heavy Ion accelerator facility dedicated to the medical use, especially for the clinical treatment of tumors. The ion species required for the clinical treatment range from 4He to 40Ar. An RF control system of the HIMAC synchrotron has been constructed. In this control system we have adopted a digital feed back system with a digital synthesizer (DS). Combining a high power system, performance of the control system have been tested in a factory (Toshiba) with a simulator circuit of the synchrotron oscillation. Following this test, we had beam acceleration test with this control system at TARN-II in INS (Institute for Nuclear Study, University of Tokyo). This paper describes the RF control system and its tested results. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC07 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC08 | Development of a VME Multi-Processor System for Plasma Control at the JT-60 Upgrade | 438 |
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| Design and initial operation results are reported of a VME multi-processor system for plasma control at a large fusion device named "the JT-60 Upgrade" utilizing three 32-bit MC88100 based RISC computers and VME components. Development of the system was stimulated by faster and more accurate computation requirements for the plasma position and current control. The RISC computers operate at 25 MHz along with two cache memories named MC88200. We newly developed VME bus modules of up/down counter, analog-to-digital converter and clock pulse generator for measuring magnetic field and coil current and for synchronizing the processing in the three RISCs and direct digital controllers (DDCs) of magnet power supplies. We also evaluated that the speed of the data transfer between the VME bus system and the DDCs through CAMAC highways satisfies the above requirements. In the initial operation of the JT-60 upgrade, it has been proved that the VME multi-processor system well controls the plasma position and current with a sampling period of 250 ¿sec and a delay of 500 ¿sec. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC08 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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| S12FC09 | Very Fast Feedback Control of Coil-Current in JT-60 Tokamak | 442 |
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| A direct digital control (DDC) system is adopted for controlling thyristor converters of power supplies in the JT-60 tokamak built in 1984. Microcomputers of the DDC were 5 MHz i8086 microprocessor and programs were written by assembler language and the processing time was under l ms. They were, however, too old in hardware and too complicated in software. New DDC system has been made in the JT-60 Upgrade (JT-60U) to control the power supplies more quickly under 0.25 and 0.5 ms of the processing time and also to write the programs used by high-level language. The new system consists of a host computer and five microcomputers with microprocessor on VMEbus system. The host computer AS3260 performs on-line processing such as setting the DDC under the discharge conditions and so on. Functions of the microcomputers with a 32-bit, 20 MHz microprocessor MC68030, whose OS are VxWorks and programs are written by C language, are real-time processing such as taking in instructions from a ZENKEI computer and in feedback control of currents and voltages of coils every 0.25 and 0.5 ms. The system is now operating very smoothly. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-ICALEPCS1991-S12FC09 | |
| About • | Received ※ 02 December 1991 — Accepted ※ 02 January 1992 — Issued ※ 04 December 1992 | |
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