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MRO Delay Line

List of Tests
INT-406-VEN-0108

The Cambridge Delay Line Team

rev 0.4 21 January 2008

Cavendish Laboratory JJ Thomson Avenue Cambridge CB3 0HE UK


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Change Record
Revision 0.1 0.2 0.3 0.4 Date 2008-01-10 2008-01-21 2008-02-04 Author(s) MF MF MF Changes Initial outline More tests added Minor changes to tests, general tidy up. Included references to top level requirements where necessary.

2008-02-08 MF

Objective
This document defines the list of tests to be undertaken for the testing of the prototype delay line and trolley.

Scope
The list is a comprehensive suite of tests defined to show that the derived requirements are met and to the extent possible in a prototype test facility that the top-level requirements can be met in the fully operational delay line. The tests listed in this document apply only to the prototype testing though they will form the basis for factory acceptance testing of the production trolley. These tests aim to demonstrate that the design and construction of the delay line structure is adequate for meeting the requirements of a 200m long delay line and that the performance of the trolley and the closed loops involving the metrology system and shear system meet requirements. The metrology system with which these test are conducted is the lab system and not the prototype metrology design which is proposed for MROI.

Reference Documents
RD1 Results of the Risk Reduction Experiments Rev. 1.0, 6th December 2005 RD2 Top-level requirements INT-406-TSP-0002

Applicable Documents
These are other review documents for review which are directly applicable, e.g. AD01 Derived Requirements INT-406-VEN-0107


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Acronyms and Abbreviations
BCA BCF BRS DL DLA ICD ICS Beam Combining Area Beam Combining Facility Beam Relay System Delay Line Delay Line Area Interface Control Document Interferometer Control System (now SCS) Interferometer MRAO Mullard Radio Astronomy Observatory NMT New Mexico Tech OPD SCS TBC TBD Optical Path Delay Supervisory Control System To be confirmed To be determined

MROI Magdalena Ridge Observatory


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Table of Contents
1 Introduction .................................................................................................................................. 5 1.1 Grouping of Tests................................................................................................................. 5 1.2 Test conditions ..................................................................................................................... 5 1.2.1 Testing at atmosphere .................................................................................................. 5 1.2.2 Testing under vacuum conditions ................................................................................ 5 2 Test Lists ...................................................................................................................................... 6 2.1 Test at atmosphere ............................................................................................................... 6 2.1.1 Trolley slew tests ......................................................................................................... 6 2.1.2 Trolley tracking tests.................................................................................................... 6 2.1.3 Trolley trajectory tests ................................................................................................. 7 2.1.4 Trolley roll and shear loop tests ................................................................................... 7 2.1.5 Datum tests................................................................................................................... 8 2.1.6 Focus mechanism tests ................................................................................................. 8 2.1.7 Trolley limits tests........................................................................................................ 8 2.1.8 Vacuum integrity test ................................................................................................... 8 2.2 Tests under vacuum ............................................................................................................. 9 2.2.1 Trolley slew tests ......................................................................................................... 9 2.2.2 Trolley tracking tests.................................................................................................... 9 2.2.3 Trolley trajectory tests ................................................................................................. 9 2.2.4 Trolley roll and shear loop tests ................................................................................... 9 2.2.5 Datum tests................................................................................................................. 10


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1

Introduction

The test list presented here is designed to show that the top level and derived requirements are met and that the performance of the system is maintained over representative observing periods. A short description of each test is given together with any specific conditions that should apply for the duration of the test. The derived requirement with which the test is associated is given in the last column of the tables. A top level requirement is identified with the letters TL followed by the section number and paragraph number. Tests are grouped into categories for convenience of referencing but this is not meant to imply any particular significance or order in testing. All tests are conducted at atmospheric pressure and but substantial subset of these tests are to be repeated under vacuum conditions. The differences between testing at atmosphere and testing under vacuum are explained below

1.1

Grouping of Tests

Tests are grouped under general categories that address some particular aspect of the requirements. These groups are: Slew tests: these test the repositioning time of the trolley, the maximum velocity and acceleration, the power consumption and trolley temperatures, and show that the metrology system maintains lock when the shear system and steering loops are closed. Tracking tests: these comprise constant velocity tests over a range of tracking velocities from 0.1mm/s to 15mm/s, sets of 10 minute long tracking tests to represent normal observation times and tracking over joins to assess the effect of the join. Trajectory tests: these test the re-positioning of a trolley from tracking at one position to tracking at another position, tracking at constant accelerations and tracking reversal and tracking offsets of 0.5µm to 10µm. Roll and shear tests: these check the operation of the shear loop, the secondary tip/tilt servo and the effect of the steering in open and closed loop. They also provide information on the deviations of the delay line pipe. Datum tests: these test the repeatability of the datum switch and the overall stability of the datum over a period of time. Focus tests: these test the resolution and stability of the cat's eye focussing system. Limit tests: these test the functionality of the limits and the characteristics of the trolley and cat's eye servos when a limit is encountered. Vacuum tests: this is a specific test of the hold time of the test rig when evacuated to less than 1mbar.

1.2

Test conditions

1.2.1 Testing at atmosphere
Testing at atmosphere is much more convenient than testing under vacuum conditions. Most tests that are met at atmosphere can be expected to meet the requirements under vacuum. The main difference in testing at atmosphere is that air in the pipe will be pushed about by the trolley and so servos will have to work harder and there is more coupling from the trolley to the cat's eye.. On the other hand air damping is also increased. The delay line pipe is left partially open at both ends to allow air to flow in or out and reduce the effect on the trolley. Special arrangements are made to hold the RF antennas, ground plane and RF absorbent material. There are no windows fitted in the metrology beam for these tests.

1.2.2 Testing under vacuum conditions
When testing under vacuum the proper end plates are installed on the delay line pipe and metrology windows are fitted whereas science beam ports are blanked off. The test rig is evacuated to approximately 0.5 mbar.


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2
2.1

Test Lists
Test at atmosphere

2.1.1 Trolley slew tests Test No. 1 Test Description Check velocity ramping under VME control by moving fixed distances (plus and minus): 4mm, 10mm, 20mm, 50mm 100mm 200mm 500mm 2m. Carry out a 17m slew with the maximum velocity set to +0.7m/s Carry out a 17m slew with the maximum velocity set to -0.7m/s Carry out a sequence of slews at maximum velocity equivalent to 380m of delay line travel Primary objective Test repositioning time Delay precision Check metrology lock Check metrology lock Check temperatures Check power Subordinate objectives Check track/slew switching Check time Check power Check time Check power Check steering performance Derived/ Requirement 2.2.1 2.2.2 (TL 5.2.4) 2.2.1 2.2.2 2.2.1 2.2.2 2.5.1

2 3 4

2.1.2 Trolley tracking tests Test No. 1a Test Description Test tracking at rates of (plus and minus) 0.1mm/s, 0.2mm/s, 0.4mm/s, 0.8mm/s and then 1 to 15mm/s in increments of 1mm/s. Steering loop open/closed as required. If necessary, repeat two constant velocity tracking tests (1mm/s and 10mm/s) with steering loop closed and actuating (may need to force actuation). Continuous tracking for 10 minutes at the following velocities: 0.2mm/s, -1mm/s, +5mm/s and -10mm/s. (may need to log in sections if log files are too long: 30s log is ~11MB) Continuous tracking across joins ­ position trolley so as to cross join at 0.2mm/s and again at 1mm/s and 5mm/s for each accessible pipe joint. Primary objective Test of OPD performance Subordinate objectives Derived Requirement (TL 5.2.6)

1b

Test of steering influence on OPD

(TL 5.2.6)

2

Test of OPD performance over typical observation time Test of performance over join ­ recovery time if out of specification

(TL 5.2.6)

3

(TL 5.2.6)


List of Tests INT-406-VEN-0108 v0.4.doc 2.1.3 Trolley trajectory tests Test No. 1 Test Description Test trajectory acquisition and time by switching from tracking at one position to tracking at another position for a range of distances e.g 4mm, 20mm, 100mm, 200mm, 500mm, 2m 10m and 14m. Test tracking at constant accelerations 0.3ms-2, 0.625ms-2, 1.25 ms-2. Test reversing direction while tracking with a realistic trajectory. Test response to fringe tracking offsets of 0.5µm and 1µm (also 10µm if can be rate limited) Primary objective Check reacquisition time & delay precision Test of OPD performance Test of OPD performance Test offset response

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Subordinate objectives

Derived Requirement (TL 5.2.4)

2 3 4

(TL 5.2.6) (TL 5.2.6) (TL 5.2.11)

2.1.4 Trolley roll and shear loop tests Test No. 1 Test Description Slew the trolley for the full length of the test rig at a constant velocity of 90mm/s With steering and tip/tilt loops closed Slew the trolley for the full length of the test rig at a constant velocity of 100mm/s while logging with steering loop off but centred and check roll. Slew the trolley for the full length of the test rig at a constant velocity of 100mm/s while logging and with steering loop off but set at maximum deviation. Operate the tip/tilt actuator between its limits in both axes and measure the resulting shear of the metrology beam using the shear sensor. Using the same results gathered in (4) obtain the slew rate of the tip/tilt device in both axes. Primary objective Check tip/tilt Subordinate Objectives Measure pipe deviation Check steering performance Check steering centre position Ensure trolley is retrievable if steering fails Derived Requirement 2.4.1

2

Check trolley balance. Check for limit of roll angle. Check tip/tilt range Check tip/tilt slew rate

-

3

-

4

2.1.2.2

5

2.1.2.3


List of Tests INT-406-VEN-0108 v0.4.doc 2.1.5 Datum tests Test No. 1 2 3 4 Primary objective Acquire datum 10 times from close range To check and check the deviation from zero at the datum switch instant before the reset. repeatability Acquire datum 10 times from different To check starting positions: at, near, far. Check datum deviation as for test 1 stability Acquire datum at various times through To check testing phase. Check deviation as for test 1 intra-night stability Acquire datum the following day. Check To check deviation as for test 1 inter-night stability Test Description

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Subordinate Objectives

Derived Requirement (TL 5.1.1) (TL 5.2.4) (TL 5.1.1) (TL 5.2.4) (TL 5.1.1) (TL 5.2.4) (TL 5.1.1) (TL 5.2.4)

2.1.6 Focus mechanism tests Test No. 1 2 Test Description Request a range of focus motions chosen to demonstrate the positioning resolution and repeatability. Measure the change in tilt of the return metrology beam while heating the trolley through continuous motion. Primary objective Test focus resolution Test focus drift Subordinate Objectives Derived Requirement 2.1.3.1 2.1.3.2

2.1.7 Trolley limits tests Test No. 1 Primary objective Drive trolley into each pre-limit and check Test limit that trolley stops within allowed distance, functionality will not drive further but will drive out of limit Drive trolley into each final limit and Test limit check that trolley stops and cannot be functionality driven. Test Description Subordinate Objectives Check cat's eye current limit. Check cat's eye current limit. Derived Requirement 2.3.1

2

-

2.1.8 Vacuum integrity test Test No. 1 Test Description Pump down to 0.2 to 0.5 mbar and check pressure over next few days Primary objective Test of seal Subordinate Objectives Test of system Derived Requirement 4.1.3


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2.2

Tests under vacuum

2.2.1 Trolley slew tests Test No. 1 2 3 Test Description Carry out a 17m slew with the maximum velocity set to +0.7m/s Carry out a 17m slew with the maximum velocity set to -0.7m/s Carry out a sequence of slews at maximum velocity equivalent to 380m of delay line travel Primary objective Check metrology lock Check metrology lock Check temperatures Check power Subordinate objectives Check time Check power Check time Check power Check steering performance Derived Requirement 2.2.1 2.2.2 2.2.1 2.2.2 2.5.1

2.2.2 Trolley tracking tests Test No. 1 Test Description Test tracking at rates of (plus and minus) 0.1mm/s, 0.5mm/s, 1mm/s, 5mm/s, 10mm/s and 15mm/s. Steering loop closed. Continuous tracking for 10 minutes at the following velocities: 0.2mm/s, 1mm/s, +5mm/s and -10mm/s. (may need to log in sections if log files are too long: 30s log is ~11MB) Primary objective Test of OPD performance Test of OPD performance over typical observation time Subordinate objectives Derived Requirement (TL 5.2.6)

2

(TL 5.2.6)

2.2.3 Trolley trajectory tests Test No. 1 Test Description Test trajectory acquisition and time by switching from tracking at one position to tracking at another position for a range of distances e.g 4mm, 20mm, 100mm, 200mm, 500mm, 2m 10m and 14m. Test response to fringe tracking offsets of 0.5µm and 1µm (also 10µm if can be rate limited) Primary objective Check reacquisition time Test step response Subordinate objectives Derived Requirement (TL 5.2.4)

2

(TL 5.2.11)

2.2.4 Trolley roll and shear loop tests Test No. 1 Test Description Slew the trolley for the full length of the test rig at a constant velocity of 90mm/s With steering and tip/tilt loops closed Primary objective Check tip/tilt Subordinate Objectives Measure pipe deviation Check steering performance Derived Requirement 2.4.1


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2.2.5 Datum tests Test No. 1 2 3 4 Primary objective Acquire datum 10 times from close range To check and check the deviation from zero at the datum switch instant before the reset. repeatability Acquire datum 10 times from different To check starting positions: at, near, far. Check datum deviation as for test 1 stability Acquire datum at various times through To check testing phase. Check deviation as for test 1 intra-night stability Acquire datum the following day. Check To check deviation as for test 1 inter-night stability Test Description Subordinate Objectives Derived Requirement (TL 5.1.1) (TL 5.2.4) (TL 5.1.1) (TL 5.2.4) (TL 5.1.1) (TL 5.2.4)