Gold: Integration of Model-based Control Systems with Artificial Intelligence and Workstations*

Our experience with model-based accelerator control started at SPEAR.. Since that time nearly al1 accelerator beamlines have been controlled using model-based application programs, for example, PEP and SLC at SLAC. In order to-take advantage of state-of-the-art hardware and software technology, the design and implementation of the accelerator control programs have undergone radical changes with time. Consequently, SPEAR, PEP and SLC all use different control programs. Since many of these application programs are embedded deep into the control system, they had to be rewritten each time. Each time this rewriting has occurred a great deal of time and effort has been spent on training physicists and programmers to do the job. Now, we have developed an integrated system called GOLD (G enetic Orbit & Lattice Debugger) for debugging and correcting trajectory errors in accelerator lattices. The system consists of a lattice modeling program (COMFORT), a beam simulator (PLUS), a graphical workstation environment (micro-VAX) and an expert system (ABLE). This paper will describe-some of the features and applications of our integrated system with emphasis on the automation offered by expert systems.-Up to now, our program has been developed to solve one type of problem that is often encountered during accelerator startup and commissioning. We have made a program that is generic because it can be used for the control of either storage rings or beamlines, large or small machines and also for the analysis of measured or simulated data. Also the integrated system can be run to automatically find errors in an accelerator lattice without human intervention. Finally, GOLD is transportable and can also be easily incorporated into any existing control system. COMFORT [I] is a lattice modeling program that performs first-order optics calculations from bends, quadrupoles, drifts and accelerator sections. COMFORT-uses as input the order, length and strength of the elements in the beamline. The user can also specify lattice function values or transfer matrix values at various fit points. The output are the transfer matrices across each element. The fits are done using a sophisticated nonlinear optimization program, NPSLAC [2]. A special version of COMFORT generates output that is used as input to the beam simulator, PLUS. PLUS [3] calculates beam trajectories at each Beam Position Monitor (BPM) including effects due to errors. These errors include beam kick errors such as: dipole field errors (due to misaligned quadropoles, miscal-ibrated bending magnet strengths); quadrupole field errors (due to quadrupole miscalibration); beam …