Real time control Logical architecture Discussion of logical architecture of real time control systems M.Jonker

Objectives Discuss real time control systems from a different perspective. I.e do not consider –why we need a real time system –how we can implement the real time system A discussion of the logical architecture will highlight some of the basic ingredients. At the end we should be able to see the problem from a larger perspective.

Objectives We will be able to find general concepts that can be specialized into solutions for specific problems. (Generalizing specific solutions may not always work). We will find new or different criteria for the physical implementation of a real time control system.

Data Processing & Summing Control knob processing Data Processing & Summing Control knob processing Objectives: be able to understand this Sources Measurement Data reduction Settings database Sources Other Intermediate Data Processing Data Surveillance Reference generators Control Feedback processing RT knob inputs Data Display Reference generators Feedback processing Measurement Data reduction Beam Abort Reference Function & settings Timing Feed-Forward

Objectives: be able to understand this IQ f IQ d MQMQ MQMQ M ij (E) function of energy given by the control system E(t) Energy function of ramp time given by the control system Start Stop t ramp ramp time generator QhQh QvQv Filter IQ d (t) IQ d reference function given by the control system IQ f (t) IQ f reference function given by the control system Q v (t) tune reference given by the control system Q h (t) tune reference given by the control system Q h Real Time Knob

Do we need a real time control system... Can we avoid it? If we deny the need for a real time control system we will end up with several real time systems ‘provided’ as specific solutions. –BI real time acquisition systems (BST, ATM? –PO (GPS-time Gbit Ethernet) –Multipole factory –RF... This will not necessarily provide an adequate framework for implementing a coherent control system.

Who is afraid of the real time control ? Real time does not mean fast and expensive. It implies reliable and deterministic. There may be many reliable and affordable solutions possible. But the implementation should not be driven by the solutions. Control: measurement, interpretation, correction –What are the measurements –Who is interpreting the data –How do we make the correction Real-time: deterministic –what are the required response times of measurement, interpretation and correction.

disclaimer I personally find the real time control system a very fascinating subject. But, I do not have the time (yet) to get deeply involved with this. However, I think it is important to share my perspectives with you because, it will help to advance in the ever ongoing real-time controls dilemma. finally, I want to make sure that this gets on the right track, so in a few years it will be a pleasure to join you in the real time control.

The following slides are taken from two previous un-presentations : LHC-RT-control-brainstorming.ppt In preparation of the LHC RT controls workshop 13-April 2000 RT-Architecture-brainstorming.ppt 25-October 2000

RT-Control Architecture If we need to implement an RT control somewhere, we should not only concentrate on specific requirement. It will be very helpful to see the problem in a larger perspective, i.e. as a specialisation of a more general problem. The aim of this presentation is to: concentrate on the essential elements taking part in the control structure. identify common control components. provide a framework for further discussions on performance and implementation issues. In this context we should not address realisation and implementation issues like: where we need the RT-control what the performance should be of the RT-control

Control connectivity Please note: The next slides show examples of connectivity in increasing complexity. It gives a logical view of how different components participating in the control are related. This should not be taken as a proposal for an actual implementation. There is no assumption made about the actual location of the various components. Certain control components with the same function are only drawn once (e.g. ramp time generator). This does not exclude that certain of this functional components may be duplicated in the actual implementation of the control system.

Control connectivity Observation Control Observation Control Transformation DataOut DataIn DataIn-DataOut Connections: Data may be more than one parameter DataOut may be connected to more than one data-in DataIn may be connected to (i.e. get its data from) more than one DataOut (we assume the data will be summed)

M ij constants given by the control system X M Q Control connectivity M ij (t) function of ramp time given by the control system Start Stop MQMQ MQMQ M ij (E) function of energy given by the control system E(t) Energy function of ramp time given by the control system Start Stop t ramp ramp time generator Filter IQ d (t) IQ d reference function given by the control system IQ f (t) IQ f reference function given by the control system Q v (t) tune reference given by the control system Q h (t) tune reference given by the control system Q h Real Time Knob IQ d IQ f QhQh QvQv

Real time control Connectivity of feedback loops: Measurement equipment Control Equipment Beam

Real time control Measurement equipment Control Equipment Beam By proper modelling, these blobs can often be controlled by a single or a few parameters Connectivity of feedback loops:

Real time control Connectivity of feedback loops: Measurement equipment Control Equipment Beam

Control connectivity PU 1 Corr.1 Corr.2 PU 2 PU 3 PU 4 PU n Calculate Orbit Bump Corr.3 Filter Start Stop t ramp ramp time generator Bump(t) Bump reference function E(t) Energy function of ramp time Corr.1(t) reference function Corr.1(t) reference function Corr.3(t) reference function Calculate Orbit Bump corrections

Control connectivity Is function generation inside or outside the digital controller ? This is part of the physical architecture sum MQMQ Start Stop t ramp ramp time generator IQ f (t) IQ f reference function given by the control system IQ f

Control connectivity ingredients Data Destinations: Data Transformations Controllers RT displays Data Transformation, Data in - Data out: Reference functions Multipole factories Filters (Feedback) Tune Matrices Orbit calculation Data transformations will need setting parameters from the controls system Data sources: Measurement RT-Knobs Data Transformations RT control can be considered as a network of: RT- connectivity: RT backbone RT configuration manager

RT control issues Hence we should answer these questions: Which Data sources –H ow much data, what frequency, potentially useful for doing what, and who said so. Which Control targets –H ow much data, what frequency, potentially useful for doing what, and who said so. Which Data Destinations, Control Origins, Feedback Applications –How much latency, need for synchronisation, etc. Do we need a configurable RT system? What are the advantages, are there any disadvantages? Is there in-house experience, commercial solutions, RT middleware ?

Identify real-time needs data sources, data destinations, control objects, control data sources, processing (feedback loops) Sources Control Destinations Origins Loops Settings database RT knobs, timing Reference values Operator

Data Processing & Summing Control knob processing Data Processing & Summing Control knob processing Identification of real-time needs Sources Measurement Data reduction Settings database Sources Other Intermediate Data Processing Data Surveillance Reference generators Control Feedback processing RT knob inputs Data Display Reference generators Feedback processing Measurement Data reduction Beam Abort Reference Function & settings Timing Feed-Forward

Identify real-time needs real-time data sources –Local orbit –Radial Position –Global Orbit –Beam Size –Beam Current –Beam Loss –Tune –Chromaticity –Beam Beam deflection –Luminosity You name it, we will control something with it? –Synchronisation

Identify real-time needs real-time data destinations –on-line displays –Beam Dump?

Identify real-time needs real-time control objects –Power converters –RF equipment –Reference settings for local feedback loops –Reference settings for RT surveillance –Measurement parameters Could we have one type of device model (or even better: hardware) for control please?

Identify real-time needs real-time control data sources –ramp functions and actual settings changes (trims) –feed forward data –feed back loops –RT knobs Where do they get the data from –RT input (timing, measurement, operator tools) –Controls data base with trim archival etc

Identify real-time needs real time processing –Operator: universal control, but real-time? –Application: feedback loops data surveillance –Note: RT processing could be distributed and partly included in the measurement, and/or in the control equipment. Example: A local orbit bump is measured with 5 pick-ups, the measurement system transforms these 5 signals into a single bump amplitude. A bump correction ‘knob’ is defined that corrects the bump amplitude using three correctors. A feedback loop takes the measured bump amplitude and regulates the feedback by controlling the bump knob. The feedback process has the responsibility to provide a stable regulation in time domain.

Logical Architecture Recommendations (to be reviewed and studied). Allow an efficient and flexible way to connect and parameterise the objects involved in RT control: –measurement, processing, control –RT network with RT agents. A system of “standard” rt-processes that can be reconfigured with configurable deterministic data channels for communication.

Physical Architecture Recommendations (to be reviewed and studied). The RT-architecture should not fix its application for the coming N years. The architecture should be open. It should allow implementing what is required today, and what may be asked tomorrow. –Example Generic reference generation agent to replace function generation capability in the electronics. Can be used for PC control, feedback reference, surveillance reference, etc.

Physical architecture … or the art of building pyramids POBI CO