LISA Pathﬁnder signals, inputs, outputs, observationshewitson/presentations/presentations_201… · LISA Pathﬁnder signals, inputs, outputs, observations M Hewitson for the LPF

LISA Pathfindersignals, inputs, outputs, observations

M Hewitson for the LPF teamLPF School, ESTEC, 28th Feb 2012

Monday, February 6, 12

M Hewitson, LPF Inputs etc, LPF School, ESTEC, 28th Feb 2012

Contents

•signals, inputs, outputs•observations

2Monday, February 6, 12


Input Signals

•Guidance signals•Actuation Commands•Commanded forces

3

controllersensor signal decoupling to actuator

Guidance[m, rad]

Actuation[m s-2, m2 s-2]

CommandedForce

[N, Nm]



Output Signals

4

•Output in form of telemetry•We can downlink a subset of available

parameters•Per investigation, we define a Science Data

Mode• tells MOC which packets to downlink

•Data is converted to engineering values by MOC and delivered to STOC

•Data analysis starts from AOs



Science Data Modes

•Choose ICE telemetry• small subset of data to downlink at the start of SC

pass• choose from one of the predefined ICE packets

•Choose Rest• choose sampling frequency (1,2,5,10)• choose packets to downlink

• all come at chosen sampling frequency• one may be at 10 Hz (unfiltered)

• include diagnostics? (yes/no)



Telemetry flow



What outputs can we get?

7

coords

OB & PM

OB PM

DMU (@ 10Hz)

dT = 3*0.1 = 0.3s

OBC

Data Conversion

Inv OMS Conversion

DFACS

Measurement Processing

Sensor Mapping

OMS outputs [m]

Guidance &Ctrl Err Calc

Guidance

Controller

guidancetest output

[m]

err signaloutput [m]

ctrl output [m s^-2]

Decoupling

external commanded

output [m s^-2]

ActuationCommands

commandedforce outputs

[N]

X

FEEPS Algorithm

CapAct AlgorithmFEEP commands

[N] CapAct Algo

Sigma Delta

[V]

[N]

Cap Act Raw

CommandedVoltages [V]

Cap Act CommandedVoltages [V]

OBC

Data Conversion

DelaydT = ((int)0.5)*0.1 = 0s

Individual ThrusterCommands [N]

1

2

3

4

5

6

7

8

9

10

o_i [m]

g_i [N/kg]

FEEP Testinputs [N]

v_i [V]

1

2

3

4



Signal Names

8

SC Name DFACS Name LTP DA Name



Guidance on x1

•In science mode 1 full optical:• x1 control coordinate controls SC x position relative

to TM1• measurement taken from OMS X1 IFO

9

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS

commanded force on X

SC Dynamics

Commandedguidance

signal = P1 + P2 sin (P3 t + P4)

o1

F_cmd_X



Cross-couplings: x1 -> ?

•Commanding x motion on SC doesn’t result in only x motion• FEEP cross-coupling

• static misalignments• beam flutter

•x motion of SC is not only sensed by X1 IFO• imperfect common-mode rejection -> X12 IFO sees

some SC x motion•x motion of SC couples to both TMs through

residual stiffness• gravitational coupling (TM-SC, TM-TM)• electrostatic stiffness from actuation voltages



Guidance x1: observations

11

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics




11

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

~1mH

z

~1.7

mHz

~3.3

mHz

~6.7

mHz

~13.

3mHz

~26.

7mHz

~53.

3mHz




11

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

~1mH

z

~1.7

mHz

~3.3

mHz

~6.7

mHz

~13.

3mHz

~26.

7mHz

~53.

3mHz




11

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

~1mH

z

~1.7

mHz

~3.3

mHz

~6.7

mHz

~13.

3mHz

~26.

7mHz

~53.

3mHz



Cross-coupling: perfect IFO•signal in o12

arises from difference of stiffness• here we use

8e-7 s-2



Cross-coupling: matched stiffness on x, perfect IFO



Cross-coupling: matched stiffness

14

common mode rejection at 10,000

Cap. Act. force commanded

on TM2



FEEP cross-talk

•Trying to move SC along x results in angular motion



Open-loop gains



Open-loop gains

16

science band



Guidance on x2

•In science mode M1 full optical:• x2 control coordinate controls x position of TM2

relative to TM1• measurement taken from OMS X12 IFO

17

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act

commanded force on TM 2 x

SC Dynamics

Commandedguidance

o12

F_cmd_x2



Cross-couplings

•Actuation on x is not perfect• other degrees-of-freedom are disturbed

•Back-reaction on SC• 2kg/423kg• small signal should be present in X1 IFO output




19

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics




19

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics




19

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics




19

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics



SC motion: back reaction

20

x 1.96/422.7

high loop gain



Cap. Act. Cross-talk



Actuation on x1• In science mode 1 full optical:

• actuation commands on x1 drive SC along x using FEEPs

• decoupling matrix decides this

22

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

Decouplingx1

F_cmd_X

o1



Decoupling

23

Theta Eta Phi x1 y1 z1 theta1 eta1 phi1 x2 y2 z2 theta2 eta2 phi2

SC

X 0 0 0 422.7 -6.7452 250.7 0 0 0 0 6.7452 -250.7 0 0 0

SC

Y 0 0 0 0 216.97 0 94.262 0 0 0 205.73 0 0 0 0

SCZ 0 0 0 0 0 216.97 2.5362 0 0 0 0 205.73 0 0 0

SCTheta 0 0 0 0 2.6419 -0.033726 109.11 0 0 0 -2.6419 0.033726 0 0 0

SC

Eta 0 0 0 0 3.1702 -309.35 0.012681 0 0 0 -3.1702 309.35 0 0 0

SC

Phi 0 0 0 0 509.77 -3.1702 0.99335 0 0 0 -509.77 3.1702 0 0 0

TM1

x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

y 0 0 0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM1z 0 -0.36848 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1theta -0.0006912 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

eta 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0 0

TM1

phi 0 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0

TM2

x 0 0 0 0 0 0 0 0 0 -1.96 0 0 0 0 0

TM2

y 0 0 -0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM2z 0 0.36848 0 0 0 0 0 0 0 0 0 0 0 0 0

TM2theta 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0 0

TM2

eta 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0

TM2

phi 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912



Decoupling

23


SC

X 0 0 0 422.7 -6.7452 250.7 0 0 0 0 6.7452 -250.7 0 0 0

SC

Y 0 0 0 0 216.97 0 94.262 0 0 0 205.73 0 0 0 0

SCZ 0 0 0 0 0 216.97 2.5362 0 0 0 0 205.73 0 0 0

SCTheta 0 0 0 0 2.6419 -0.033726 109.11 0 0 0 -2.6419 0.033726 0 0 0

SC

Eta 0 0 0 0 3.1702 -309.35 0.012681 0 0 0 -3.1702 309.35 0 0 0

SC

Phi 0 0 0 0 509.77 -3.1702 0.99335 0 0 0 -509.77 3.1702 0 0 0

TM1

x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

y 0 0 0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM1z 0 -0.36848 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1theta -0.0006912 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

eta 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0 0

TM1

phi 0 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0

TM2

x 0 0 0 0 0 0 0 0 0 -1.96 0 0 0 0 0

TM2

y 0 0 -0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM2z 0 0.36848 0 0 0 0 0 0 0 0 0 0 0 0 0

TM2theta 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0 0

TM2

eta 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0

TM2

phi 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912



Example:

24

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

Decouplingx1



Example:

24

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

Decouplingx1



Example:

24

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

Decouplingx1



Example:

24

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

Decouplingx1



Actuation on x2

•In science mode M1 full optical:• actuation commands on x2 drive TM2 along x using

Cap. Act.• decoupling matrix decides this

25

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics

Decouplingx2

o12

F_cmd_x2



Decoupling

26


SC

X 0 0 0 422.7 -6.7452 250.7 0 0 0 0 6.7452 -250.7 0 0 0

SC

Y 0 0 0 0 216.97 0 94.262 0 0 0 205.73 0 0 0 0

SCZ 0 0 0 0 0 216.97 2.5362 0 0 0 0 205.73 0 0 0

SCTheta 0 0 0 0 2.6419 -0.033726 109.11 0 0 0 -2.6419 0.033726 0 0 0

SC

Eta 0 0 0 0 3.1702 -309.35 0.012681 0 0 0 -3.1702 309.35 0 0 0

SC

Phi 0 0 0 0 509.77 -3.1702 0.99335 0 0 0 -509.77 3.1702 0 0 0

TM1

x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

y 0 0 0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM1z 0 -0.36848 5.79E-17 0 0 0 0 0 0 0 0 0 0 0 0

TM1theta 0.0006912 0 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

eta 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0 0

TM1

phi 0 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0

TM2

x 0 0 0 0 0 0 0 0 0 -1.96 0 0 0 0 0

TM2

y 0 0 -0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM2z 0 0.36848 -5.79E-17 0 0 0 0 0 0 0 0 0 0 0 0

TM2theta 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0 0

TM2

eta 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0

TM2

phi 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912



Decoupling

26


SC

X 0 0 0 422.7 -6.7452 250.7 0 0 0 0 6.7452 -250.7 0 0 0

SC

Y 0 0 0 0 216.97 0 94.262 0 0 0 205.73 0 0 0 0

SCZ 0 0 0 0 0 216.97 2.5362 0 0 0 0 205.73 0 0 0

SCTheta 0 0 0 0 2.6419 -0.033726 109.11 0 0 0 -2.6419 0.033726 0 0 0

SC

Eta 0 0 0 0 3.1702 -309.35 0.012681 0 0 0 -3.1702 309.35 0 0 0

SC

Phi 0 0 0 0 509.77 -3.1702 0.99335 0 0 0 -509.77 3.1702 0 0 0

TM1

x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

y 0 0 0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM1z 0 -0.36848 5.79E-17 0 0 0 0 0 0 0 0 0 0 0 0

TM1theta 0.0006912 0 0 0 0 0 0 0 0 0 0 0 0 0 0

TM1

eta 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0 0

TM1

phi 0 0 0 0 0 0 0 0 -0.0006912 0 0 0 0 0 0

TM2

x 0 0 0 0 0 0 0 0 0 -1.96 0 0 0 0 0

TM2

y 0 0 -0.36848 0 0 0 0 0 0 0 0 0 0 0 0

TM2z 0 0.36848 -5.79E-17 0 0 0 0 0 0 0 0 0 0 0 0

TM2theta 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0 0

TM2

eta 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912 0

TM2

phi 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -0.0006912



Example

27

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics

Decouplingx2



Example

27

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics

Decouplingx2



Example

27

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics

Decouplingx2



Example

27

OMS X12 DMU

DFACS

Cap. Act.Algo

Cap. Act


SC Dynamics

Decouplingx2



Commanded force on SC

•Same as actuation on x1•Just scaled by SC mass

28

OMS X1 DMU

DFACS

FEEPSAlgo

FEEPS


SC Dynamics

Decouplingx1

F_cmd_X

o1



Commanded force on TM1 x

•In science mode M1 full optical:• open loop force on TM1 along x• at low frequency (high gain) SC follows• X1 IFO observes no signal (at low f)• X12 IFO sees full signal

• TM2 follows more slowly

29

injection



How much motion do we expect to observe in X1?

•Apply 0.25 nN force on TM1at 53mHz•Displacement:

30

x =F

!

2m1

[N]

[s�2][kg]

x =2.5⇥ 10�10

(2⇡ · 0.053)2 · 1.96[N]

[s�2][kg]= 1.15[nm]

•Loop gain at 53mHz is about 2• so we should observe about 0.6 nm



IFO X1: relative position of SC and TM1 along x

31

~1mHz ~1.7mHz ~3.3mHz~6.7mHz

~13.3mHz

~26.7mHz~53.3mHz




31


~13.3mHz

High-gain, SCfollows TM1 closely

~26.7mHz~53.3mHz




31


~13.3mHz

High-gain, SCfollows TM1 closely

~26.7mHz~53.3mHz

Low-gain, SCcan’t follow



Check IS reading

•Measures TM to SC (TM housing)



SC motion

•We apply 52nN of force on SC•This results in a motion of 1.1nm•BUT it’s out of phase with the 1.1nm motion of

TM1 by about XX degrees• relative motion observed with X1 is about 0.6nm



IFO X12: relative x position of TM1 and TM2



IFO X12: relative x position of TM1 and TM2



How much do we expect to observe in X12?

•At 53 mHz the suspension loop is essentially open• TM2 doesn’t move• X12 should see the full motion of TM1 relative to the

bench (SC)

35

detrended version of last

signal



Check IS•IS measures position of TM2 relative to SC (TM

housing)



Commanded force on TM2 x•In science mode M1 full optical:

• open loop force on TM2 along x• suspension loop has no gain above 1mHz• TM2 will just move as commanded• X1 will observe ~0

• back reaction->SC motion• X12 will observe full motion of TM2

37

injection



How much with TM2 move?

38

•Apply 0.25 nN force on TM1at 53mHz•Displacement:

x =F

!

2m1

[N]

[s�2][kg]

x =2.5⇥ 10�10

(2⇡ · 0.053)2 · 1.96[N]

[s�2][kg]= 1.15[nm]

•Loop gain at 53mHz is close to 0• so we should observe 1.15 nm



IFO X1 observation



IFO X12 observation



Confirm with IS measurement

41

~1.2nm

~6pm

Consistent with ratio of masses

~1/200


Documents

LISA Pathﬁnder signals, inputs, outputs, observationshewitson/presentations/presentations_201… · LISA Pathﬁnder signals, inputs, outputs, observations M Hewitson for the LPF