Transcript Document

LYRA Instrument and Data Manager
Software Requirements Analysis
Spacebel, 5/04/05
Page 1
Agenda
•
•
•
•
•
Concept description
LIM requirements presentation (SBI)
LDM requirements presentation (SBI)
Interface issues
Open questions
Spacebel, 5/04/05
Page 2
Concept description
PROBA 2 orbit
• Sun synchronous
• LTAN: 6:00
• See emails F.Teston for details
eclipse duration
14/04/03 0:00
26/09/02 0:00
10/03/02 0:00
time [s]
•Eclipses:
• approximately 3
months eclipse season
• rest of the year: no
eclipses
• maximum eclipse
duration approx. 1100
sec.
22/08/01 0:00
03/02/01 0:00
18/07/00 0:00
00/01/00 0:00
10/10/06 0:00 28/04/07 0:00 14/11/07 0:00 01/06/08 0:00 18/12/08 0:00 06/07/09 0:00
date
Spacebel, 5/04/05
Page 3
Concept description
PROBA 2 Pointing
1. Frames definitions
Sun frame (Xsun, Ysun, Zsun)
Xsun is spacecraft-sun axis ( = unit(Rsun – Rsc) where Rsun is the
apparent sun vector from the Earth (Sun ephemeris) and Rsc is the
spacecraft position vector. If S/C position is unknown onboard, Rsc is
set to zero.
Ysun is perpendicular to Xsun, in the plane defined by Xsun and the normal to
the ecliptic plane, pointing towards the northern hemisphere.
Ysun
Xsun
Rsc
Sun
Earth
Rsun
Spacebel, 5/04/05
Page 4
Concept description
S/C Fixed Body Frame
Mechanical frame (Xmech, Ymech, Zmech)... With respect to S/C
Payload frame (Xpl, Ypl, Zpl)...With respect to SWAP
Spacecraft fixed body frame (Xbof, Ybof, Zbof) ... Related to Payload
frame, but origin in S/C COG. Reference frame for spacecraft attitude control.
Spacebel, 5/04/05
Page 5
Concept description
left
B
A
PROBA 2 Pointing
C
left
left
left
2. Pointing in observation mode
Illuminated face of
the Earth
D
 four (baseline, up to 8 possible) large-angle rotations of 90° (or 360° /
number of rotations) attitudes are commanded over one orbit in order to avoid
blinding of the star trackers; For the rest of presentation: baseline number of
rotations assumed)
 the timing of the manoeuvres is such that the exclusion angles from the star
trackers towards the earth are maximised; (performed on board -> cont. variation)
 the 90° manoeuvres will take a few minutes and will be centred around these
optimal switching times;
 the time until the next rotation is continuously provided;
 paving rotations are defined in the original sun frame.
Spacebel, 5/04/05
Page 6
Concept description
PROBA 2 Pointing
2. Pointing in observation mode
SUN
Large-angle rotation around
XSUN
SUN*
Paving rotation around
YSUN and ZSUN
REF
The observation mode is commanded as follows:
• the large rotation is commanded as a quaternion in the SUN frame:
[q1cmd, 0, 0, q4cmd];
• the commanded large angle rotations will be taken from a list (of maximum 8) quaternions,
configured by the ground;
• the index of the currently used large angle rotation will continuously be provided;
• the paving rotation is commanded as a quaternion in the SUN frame:
[0, q2paving, q3 paving, q4 paving]
Spacebel, 5/04/05
Page 7
Concept description
• LIM mode diagram
Off
FDIR/TC
FDIR/TC
TC
Warmup
TC/auto Acquisition
TC/auto
TC/auto
FDIR
Idle
Spacebel, 5/04/05
Page 8
Concept description
• Mode simplification:
–
–
–
–
Off (CSL/ROB survival mode -> idem SWAP)
Idle (CSL/ROB night mode -> idem SWAP)
Warm-up (CSL/ROB stand-by mode -> idem SWAP)
Acquisition (CSL/ROB nominal modes)
• Modes not implemented in SWIM:
– First swtich on: will be performed by uploaded procedure
– Bake-out mode: uploaded or onboard procedure
– Calibration mode: uploaded or onboard procedure, using
manually the imaging mode with different pointing
configurations
Spacebel, 5/04/05
Page 9
Concept description
• Sequence diagram Nominal observation
AOCS
manager
operator
Payload
manager
Data
manager
IIU
LYRA
Set observation mode
Configure pointing table
Configure instrument
Configure data manager
Activate warm-up mode
Close lumps
initialisation
Define & enable mode monitoring
Check VFC2
Check VFC1
Switch on LOB
Open cover
Read times to next
eclipse entry&exit
Wait for sun visibility period
Activate acquisition mode
Set AOCS in fixed off pointing
Spacebel, 5/04/05
Page 10
Switch on LOB
Concept description
Open cover
Read times to next
eclipse entry&exit
AOCS
Payload
Data
manager
manager
manager
Wait
for sun visibility period
IIU
LYRA
Activate acquisition mode
Set observation mode
Configure pointing
table in fixed off pointing
Set AOCS
Configure instrument
Wait TBD sec (off pointing movement duration)
Configure data manager
Reload ASIC
Activate warm-up mode
Send acquisition Cadence
Close lumps
initialisation
Define & enable mode monitoring
Check VFC2
Check VFC1to VFC
Apply 0V/2.5V/5V
Switch on LOB
Open cover
Switch ON/OFF LED
Read times to next
eclipse entry&exit
Repeat every
LED-Pulse_Period
seconds
Repeat every
VFC_CAL Period
seconds
Send data
Repeat until end of
sun-visibility period
(eclipse duration >
minimum duration of idle)
Wait for sun visibility period
Activate acquisition mode
Read times to next
Set AOCS
in entry&exit
fixed off pointing
eclipse
Calculate duration of idle time
Wait TBD sec (off pointing movement duration)
Reload ASIC
Activate idle mode
Send acquisition Cadence
Close lumps
Spacebel, 5/04/05
Page 11
LED-Pulse_Period
seconds
Send data
sun-visibilit
(eclipse du
minimum dura
Concept description
Read times to next
eclipse entry&exit
AOCS
manager
operator
Calculate duration of idle time
Payload
Data
manager
manager
IIU
LYRA
Activate idle mode
Set observation mode
Close lumps
Configure pointing table
Power off CD heaters
Configure instrument
Power off all heads
Configure data manager
Activate warm-up mode
Switch off all LEDS
Power VFC’s Off
Close lumps
Close Covers
initialisation
Read current time
Define & enable mode monitoring
Check VFC2
Activate warm up mode, TBD seconds before end of Idle mode
Check VFC1
Switch on LOB
Open cover
Read times to next
eclipse entry&exit
Wait for sun visibility period
Activate acquisition mode
Set AOCS in fixed off pointing
Wait TBD sec (off pointing movement duration)
Reload ASIC
Spacebel, 5/04/05
Page 12
Concept description
Spacebel, 5/04/05
Page 13
•Open questions
Spacebel, 5/04/05
Page 14
• Interace issues
Spacebel, 5/04/05
Page 15