5.2. Degrees of Freedom#
The table below shows an overview of the different elementary mechanical degrees of freedom of the telescope subsystems (AO subsystems are not included in this table). Axis groups are identified specifically. The first column identifies the name of the mechanism; the second column the number of instances; the Axes column identifies the number of axes per instance; the DOF column identifies the total number of degrees of freedom; the Controller Profile Mode column identifies the motion control profile as defined in IEC 61800-7 [IEC61800-7-1]; and the Actuator Type column identifies the generic category of the actuator.
Mechanism |
# |
Axes |
DOF |
Controller Profile Mode |
Actuator Type |
|
|---|---|---|---|---|---|---|
M1 |
||||||
Hardpoint X, Y, Z |
7 |
6 |
42 |
Interpolated Position |
Axis Group |
|
Hardpoint Actuator |
42 |
1 |
42 |
Cyclic Synchronous Position |
Servo motor |
|
Triple Support |
595 |
3 |
1785 |
Force |
Pneumatic |
|
Single Support |
560 |
1 |
560 |
Force |
Pneumatic |
|
Fan Assemblies |
322 |
1 |
322 |
Profile Velocity |
3-Phase Fan |
|
Mixing Valve |
7 |
1 |
7 |
Profile Position/Velocity |
Valve/Pump |
|
Mirror Cover (off-axis) |
6 |
1 |
6 |
Profile Position |
Servo motor |
|
Mirror Cover (on-axis) |
6 |
1 |
6 |
Profile Position |
Servo motor |
|
M2 |
||||||
Positioner X, Y, Z, Rx, Ry, Rz |
7 |
6 |
42 |
Interpolated Position |
Axis Group |
|
Linear Actuator |
42 |
1 |
42 |
Cyclic Synchronous Position |
Stepper Motor |
|
FSM, Tip, Tilt, Piston |
7 |
3 |
21 |
Interpolated Position |
Axis Group |
|
FSM Actuator |
21 |
1 |
21 |
Cyclic Synchronous Position |
Piezo |
|
FSM Pres/Vac Support |
7 |
1 |
7 |
Profile Position |
Pneumatic Valve |
|
M3 |
||||||
Deployment |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
Rotation |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
Tip, Tilt, Piston |
1 |
3 |
3 |
Interpolated Position |
Axis Group |
|
M3 Actuator |
3 |
1 |
3 |
Cyclic Synchronous Position |
Servo motor |
|
AGWS Probe Arms |
||||||
AGWS Arm Stage |
4 |
3 |
12 |
Interpolated Position |
Axis Group |
|
Azimuth |
4 |
1 |
4 |
Cyclic Synchronous Position |
Servo motor |
|
Radial |
4 |
1 |
4 |
Cyclic Synchronous Position |
Servo motor |
|
Focus |
4 |
1 |
4 |
Cyclic Synchronous Position |
Servo motor |
|
Pick-off Mirror Tilt |
4 |
1 |
4 |
Profile Position |
Voice Coil |
|
Fold Mirror Tilt |
4 |
1 |
4 |
Profile Position |
Voice Coil |
|
Sensor Select |
4 |
1 |
4 |
Profile Position |
Servo motor |
|
Ap/Cal Source Select |
4 |
1 |
4 |
Profile Position |
Servo motor |
|
TT7 De-Rotation |
4 |
1 |
4 |
Profile Position |
Newport motor |
|
AGWS Phasing Camera |
||||||
Phasing Camera Stage |
1 |
3 |
3 |
Interpolated Position |
Axis Group |
|
Azimuth |
1 |
1 |
1 |
Cyclic Synchronous Position |
Servo motor |
|
Radial |
1 |
1 |
1 |
Cyclic Synchronous Position |
Servo motor |
|
Focus |
1 |
1 |
1 |
Cyclic Synchronous Position |
Servo motor |
|
Pick-off Mirror Tilt |
1 |
1 |
1 |
Profile Position |
Voice Coil |
|
Fold Mirror Tilt |
1 |
1 |
1 |
Profile Position |
Voice Coil |
|
AGWS On-Axis AGWS |
||||||
OAWFS Depolyment |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
OAWFS Focus |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
Sensor Select |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
Ap/Cal Source Select |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
Pick-off Mirror Tilt |
1 |
1 |
1 |
Profile Position |
Servo motor |
|
Mount |
||||||
Azimuth Axis |
1 |
1 |
1 |
Cyclic Synchronous Position |
Axis Group |
|
Azimuth Forcers |
4 |
1 |
4 |
Cyclic Synchronous Torque |
Servo motor |
|
Elevation Axis |
1 |
1 |
1 |
Cyclic Synchronous Position |
Axis Group |
|
Elevation Forcers |
4 |
1 |
4 |
Cyclic Synchronous Torque |
Servo motor |
|
HBS Pump |
1 |
1 |
1 |
Profile Velocity |
Induction motor |
|
Azimuth Cable Wrap |
1 |
1 |
1 |
Cyclic Synchronous Position |
Servo motor |
|
Elevation Cable Wrap |
2 |
1 |
1 |
Cyclic Synchronous Position |
Servo motor |
|
Locking Pins |
2 |
1 |
2 |
Profile Position |
Linear Actuator |
|
Counter Weights Vertical |
4 |
1 |
4 |
Profile Position |
Servo motor |
|
Counter Weights Horizontal |
2 |
1 |
2 |
Profile Position |
Servo motor |
|
GIR |
||||||
Rotation Axis |
1 |
1 |
1 |
Cyclic Synchronous Position |
Axis Group |
|
Friction Actuator |
2 |
1 |
2 |
Cyclic Synchronous Torque |
Servo motor |
|
GIR Cable Wrap |
1 |
1 |
1 |
Cyclic Synchronous Position |
Servo motor |
|
GIR Counter Weights |
1 |
2 |
2 |
Profile Position |
Servo motor |
|
DG Instrument Deployment |
4 |
1 |
4 |
Profile Position |
Linear Actuator |
|
Corrector-ADC |
||||||
Deployment |
1 |
1 |
1 |
Profile Position |
Stepper motor |
|
Locking Mechanism |
2 |
1 |
2 |
Profile Position |
Pneumatic |
|
Prism Rotators |
2 |
1 |
2 |
Cyclic Synchronous Position |
Stepper motor |
|
Total |
76 |
3005 |
||||
There are a total of 77 different types of axes; some of them have multiple instances, for a total of 3005 mechanical degrees of freedom. Despite this large number, only 5 motion control profiles, based on the IEC 61800-7-201/301 [IEC61800-7-201] [IEC61800-7-301] standard, are necessary to implement the elementary degrees of freedom. This enables the possibility of a standardized motion platform.