# the assignment is attached to the zip file but here is some of it so u have an i

the assignment is attached to the zip file but here is some of it so u have an i

the assignment is attached to the zip file but here is some of it so u have an ideaSV Basic Properties:
– SV has same 3 reaction wheels (RWs) as & MOI as HW4
– Body-mount radiator normal: -?2 (point away from sun and Earth for max efficiency)
– Solar panel normal: ― ?3 (point towards sun whenever possible)
– Payload boresight: ?3 (point this axis towards targets when asked to)
– Sun direction: ― ?2
– Control Law: ? = ?? ??(1:3) + ??? + ?? ∑? ― 4
? ??(1:3)∆??
?2
o Gains: ?? = 70 ?? = 1200 ?? = 30
SV Thruster Properties:
– 8x 1 N thrusters (See
properties sheet on
CANVAS)
– Nominal thrust is 0.9 N
at beginning of life (BOL)
– Tank filled with 5.5 kg
of propellant (LMP-103S)
– Assume each pulse
consumes 6.93E-05
kg/pulse where each
pulse is 100 ms in
duration (same as
controller frequency)
CASE 1 (1 pt) – Thruster Detumble to Sun Safe Mode
Goal: Detumble SV only using thrusters and point solar panels
directly at sun (see fig.)
Requirements:
Use thrusters in model as shown above (turn RWs off)
Initial quaternion: ?(0) = [ ―0.3062 0.1768 0.362 0.839]?
Final quaternion: see image on right
SV initial angular rates: ??(0) = ?
SV final angular rates: ?? = ?
Initial & final RW spin rates: ?(0) = 2?
s ]
Analysis time period: 0 – 1,000 s
Deliverables:
a. Explain which thruster pairs need to be fired for control about each SV axis, both
+ and – torque needed to attain 3-DOF control. For example, “thrusters 5 & 1 fire
together for torque about the ― ?2 axis”
b. Explain how much torque is applied when thrusters are firing in the pairs as
described in part a. of this problems – both positive and negative torques?
c. Provide graphical screenshots showing the initial and final SV orientations
d. Write 2-3 sentences explaining “bang-bang” control and show evidence in the
plots where you see this type of control in effect
e. How much propellant did the thrusters consume (kg & percentage of total)?
CASE 2 (1 pt) – Thruster & RW Detumble to Sun Safe
Goal: Detumble SV using thrusters and RWs and point solar panels
at sun
Requirements:
Use thrusters and RWs, but never at the same time
Initial quaternion: ?(0) = [ ―0.3062 0.1768 0.362 0.839]?
Final quaternion: see image on right
SV initial angular rates: ??(0) = ?
SV final angular rates: ?? = ?
Initial RW spin rates: ?(0) = 2?
s ]
Analysis time period: 0 – 1,000 s
Commanded Attitude with
constraints applied
Commanded Attitude with
constraints applied
Deliverables:
a. Provide graphical screenshots (main screen w/values showing) showing the initial
and final SV orientation
b. Write 2-3 sentences explaining when thrusters are used and when RWs are used
– show they are not used at the same time
c. How much propellant did the thrusters consume to detumble and compare to
Case 1? Was it less?
CASE 3 (1 pt) – Disturbance Torque
Goal: Use RWs and thrusters to fight a gravity gradient disturbance torque
Requirements:
Initial quaternion: ?(0) = [0 0 0 1]?
Final attitude: ?3 axis pointed at ? = 1
3[1 1 1]
Final attitude: ― ?2 axis pointed from sun ( ― ?2) as well as
you can
SV initial and final angular rate: ??(0) = ?
Initial RW spin rates: ?(0) = 2?
s ]
Dist. Torque: M_b_ext = [ 0.001 0.001 0.001 ]? [Nm]
Analysis time period: 0 – 2,600 s (may be greater to see RW saturation)
Deliverables:
a. Provide graphical screenshots (main screen with values) showing starting and
final SV orientations and values
b. Plot the total SV angular momentum ?? in the inertial frame and RW speeds –
explain in 2 sentences what is occurring (1 sentence per topic)
c. Did RW rates change or saturate? Provide a plot and 2 sentences of explanation
BONUS QUESTIONS:
a. (1 POINT) Your boss said Case 2 uses too much propellant. Figure out how to
reduce propellant by half. Your boss said to turn in evidence to prove it and 2
sentences explaining how you did it.