Real time controlLogical 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 processingControl knob

processing

Data Processing & Summing

Control knob processing

Objectives: be able to understand this

Sources

Measurement Data reduction

Settings database

SourcesSourcesSourcesSources

Other Intermediate Data Processing

Data Surveillance

Reference generators

ControlControlControlControl

Feedback processing

RT knob inputs

Data Display

Reference generators

Reference generators

Feedback processing

Feedback processing

Measurement Data reduction

Measurement Data reduction

Beam Abort

Reference Function & settingsTiming

Feed-ForwardFeed-Forward

Objectives: be able to understand this

IQf IQd

MQMQ

Mij(E)function of energy given by the control system

E(t)Energy function of ramp time given by the control system

Start

Stop

tramp

ramp time generator

Qh

Qv

Filter

Filter

IQd(t)

IQd reference

function given by the control system

IQf(t)

IQf reference

function given by the control system

Qv(t)tune reference given by the control system

Qh(t)tune reference given by the control system

Qh

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 thereal 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.ppt25-October 2000

RT-Control ArchitectureIf 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)

Mij

constants given by the control system

X MQ

Control connectivity

Mij(t)function of ramp time given by the control system

Start

StopMQMQ

Mij(E)function of energy given by the control system

E(t)Energy function of ramp time given by the control system

Start

Stop

tramp

ramp time generator

Filter

Filter

IQd(t)

IQd reference

function given by the control system

IQf(t)

IQf reference

function given by the control system

Qv(t)tune reference given by the control system

Qh(t)tune reference given by the control system

Qh

Real Time Knob

IQdIQf

Qh

Qv

Real time controlConnectivity of feedback loops:

Measurem

entequipm

ent

Control EquipmentBeam

Real time control

Measurem

entequipm

ent

Control EquipmentBeam

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:

Measurem

entequipm

ent

Control EquipmentBeam

Control connectivity

PU1

Corr.1 Corr.2

PU2 PU3 PU4 PUn

Calculate OrbitBump

Corr.3

Filter

Start

Stop

tramp

ramp time generator

Bump(t)Bump reference function

E(t)Energy function of ramp time

Corr.1(t)reference functionCorr.1(t)reference function

Corr.3(t)reference function

Calculate OrbitBump corrections

Control connectivity

Is function generation inside or outside the digital controller ?This is part of the physical architecture

sum

MQ Start

Stop

tramp

ramp time generatorIQf(t)

IQf reference

function given by the control system

IQf

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– How much data, what frequency, potentially useful for doing what, and who said so.

• Which Control targets– How 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 processingControl knob

processing

Data Processing & Summing

Control knob processing

Identification of real-time needs

Sources

Measurement Data reduction

Settings database

SourcesSourcesSourcesSources

Other Intermediate Data Processing

Data Surveillance

Reference generators

ControlControlControlControl

Feedback processing

RT knob inputs

Data Display

Reference generators

Reference generators

Feedback processing

Feedback processing

Measurement Data reduction

Measurement Data reduction

Beam Abort

Reference Function & settingsTiming

Feed-ForwardFeed-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

PO BI

CO