Sightline Servo Control Technology

Sightline Servo Control Technology

Matt MacDonald

Selex Technical Fellow

Sightline Control and Navigation Systems Design Group Leader

2 © 2014 Selex ES Ltd – All rights reserved

Contents

Introduction

Technology Heritage

Technology Competencies

Servo Design & Development

Future


Introduction

Both EO and Radar products essentially consist of 3 key sub-systems:

Receiver - EO Camera, Quad diode or Radar Rx etc

Transmitter - Laser or Radar Tx

Beam Pointing - Gimbal, stabilised mirror, Radar ESCAN array etc

Edinburgh has a vast Ferranti-era design heritage in pointing servos from both the EO Targeting and Radar sectors of the business – see next two slides

Servo engineering has been a core EO systems integration specialism since the founding of the Edinburgh based EO business in 1966

Basildon has also had a notable presence in EO Servo products such as MRT, Sea Owl, Titan and the Stormshadow seeker head.

With over 1500 DIRCM Transmitter units delivered into service, the next generation MPT now in low rate production and the latest Eclipse/SPT system in the development pipeline, Selex in Edinburgh has the leading DIRCM sightline servo control capability in the World


FERRANTI SCOTLAND – EO & NAV HERITAGE Is

t_E

_X

XX

XX


FERRANTI SCOTLAND - RADAR HERITAGE


EO Pointing System Heritage - Basildon

MRT

ALLTV

SEA-OWL

Titan 385

Stormshadow

Missile Seeker Head


Laser DIRCM Product Line


Technology Competencies

Control Theory Domain Knowledge: Sightline Pointing, Tracking and Stabilisation

Simulation and modelling Component technical Knowledge – motors, encoders, IMUs

Key component Vendor knowledge Mechanism Design Knowledge Sightline and Control Systems Test knowledge General Systems Engineering Knowledge: From spec-it to sell-off


Servo Systems Design

Ideally a Model Driven Process

Practically model referenced at least

Key requirements are: Pointing Accuracy

Slew time

Tracking accuracy

Sightline Jitter

Achieving these requirements over

the full environmental envelope is

nearly always a significant challenge


System

Requirements

Specification

Sightline Sub-

system Budget

(Model)

Static Pointing Errors (Optical Engineering)Structural deflection Errors (Mech Eng)

Test Equipment Accuracy (TE Eng)

SIMULINK

MODEL

Servo Rapid

Prototype

Control Tests

(Servo X-model)

Rapid Prototype

Performance Tests(Servo X-model)

Components &

Mechanism

Requirements

Specs

Full Development

Project

DSP/FPGA based

HardwareTarget

Servo Component &

Mechanism

Testing

(System Identification)

Sightline Servo Rapid Development Process

Servo Design

DocumentOpen-loop frequency response

Gain/Phase Margins

Step response etc

Full Tracking/stabilisation

Performance Tests under

temp/vib/OSM

Full Development

Integration

Early System

Performance Risk

Management

information to Project

Support

Sightline Servo

Subsystem Reqts Spec

ICDTest/Verfification

Spec

Representative

Servomechanism

Supplied by

Project

Validate

Verify

Verify

Validate

LabVIEW SIT

C-code/

SYSGEN

Plant Model

Validation

Design

Rapid Prototype TestPlant & Servo

Experimental Rig

(X-model)

Procure Mechanism

Plant Transfer Function

Friction & OoB tests


Servo Systems Development

Testing and model validation are the keys to a successful Servo Systems Engineering development:

Component testing

Mechanism “plant identification” testing

Servo model validation testing

Xperimental model performance testing

Fully Configured System performance testing

Environmental testing

Possibly “Test Driven and Model Referenced” would be a better description of the Servo development process?


Component/sub-system Testing - Motor & Drive Control


Servo Rapid Prototyping – the X-model

Objectives: To test that the

mechanism design meets its spec

and to validate/develop the overall

control systems model


Servo Lab


The Future

Radar ESCAN technology has reduced the need for mechanical beam steering – but not entirely

EO solid-state beam pointing based on optical phased array technology currently tends to have significant FoR and/or wavelength limitations

DIRCM and Advanced Targeting applications tend to demand hyper-hemispherical beam pointing

Conventional servomechanism based EO Sightline beam pointing is expected to remain an important core technology in this domain for many years to come

Documents

Sightline Servo Control Technology