15jan01 Tracking error on sine wave,
torque output, and measure friction.
16jan01 Ramp the dac output -10 to 10 counts (static,moving friction).
30jan01 Calibrate sliderule potentiometer versus encoder.
06jul01 Fiber,cable interconnections.
09jul01 Tertiary simulator output.
02aug01 Sine wave with motors installed on the tertiary.
02/08aug01 rfi from tertiary electronics and motors.
mar02 Focusing with the tertiary.
B will represent a fiber distribution box. B1.n will be connector n on the box.
P,C will be patch cables that connect to boxes (B).
Fiber cables can plug into the front (what the user sees) or the rear of a box.
- pntp2 . mvme167 single board computer in pointing vme crate. 3rd cpu from the left in the crate. The ethernet exits from the back of the cpu.
- B1 - Conrol room fiber distribution box #1.
- B2 - Gregorian distribution box # 2 in the dome transmitter room.
- B13 - turret floor distribution box on the left of the turret controler. It has two rows of 6 connectors on the left side B13L.(1-12) and 12 connectors on the right side (B13R.(1-12).
- B14 - service platform fiber distribution box.
- C1 - 36 pair multimode cable connecting B1rear -> B2rear.
- P1,P2 .. patch cables from pointing vme crate to B1front. Were also refered to as PA,PB.
- P6- is the fiber cable that goes from the gregorian dome box B2front to the fixed turret floor B13Rrear. (This was refered to as Patch cable 6 so check the labels).
- P14 - cable from B13Lrear to B14rear.
- originates at pnting vme crate pntp2 (3rd cpu from right connector in rear).
- Rx (at pnt) P1.6 -> B1.8front=B1.8rear->C1.8
- Tx (at pnt) P1.7 -> B1.9front=B1.8rear-> C1.9
- C1.8 -> B2.8rear, C1.9 -> B2.9rear
- B2.8front->P6.3 ->B13R.3rear (Rx at pnt.. will be Tx at tertiary).
- B2.9front->P6.4 ->B13R.4rear (Tx at pnt.. will be Rx at tertiary).
Need to define the cable that goes from B2 -> tertiary box.
A simulator has been written in idl to model the different parameter setting for the tertiary: (PI loop parameters, maxAcceleration time, maxVelocity, etc..). The idl code is in idl/ter/sim. The file setup.datdef holds the default setup info. The parameters are:
The figures show the results of the simulator. The horizontal and tilt drives have the same maximum velocity (3.5 in/sec) while the vertical drives can go at a maximum velocity of 2 inches/sec. There are separate plots for vertical and tilt/hor.
- piBw - the PI loop bandwidth in hertz.
- piDamping - the PI damping factor.
- maxVelDacCnts - will limit the maximum velocity we will allow. The dac max output is 2048 so a value of 1024 would limit you to .5 of maximum velocity.
- accTm - This is the time to go from 0 velocity to dacVelocity of 2048 counts (not the value in maxVelDacCnts).
- kfGain is the PI loop feed forward gain.
- kiThr is the encoder count error where the PI integral term is turned on. Above this value the KI term is set to zero.
Fig 1. 5 inch move at maximum velocity.For the upper plot is the vertical drive while the lower plot is the hor/tilt drive. The PIbw,damping,kiThr, maxDACnts, kf were fixed. The accTm was varied from .1 to 1 seconds (we use .5 seconds for the real tertiary). The vertical axis is the position error but an offset for each accTm has been added for plotting purposes. The horizontal value on the right of each line is posErr=0. The acceleration limit causes the overshoots. By making the accTm smaller (accel limit larger) you can reduce the overshoot. You can also see that the vertical drives take longer to do the move since they have a smaller max velocity. Fig 2. 1 inch move at max velocity and then start a sine wave.
The upper plot is the vertical drives while the lower is the horizontal/tilt. The parameters piBw,piDamping, maxVelDacCnts,accTm,damping are held constant. The amplitude of the sine wave is .1 inches. The frequency of the sine wave varies from .1 to 1 hertz. The system oscillates down to frequencies of .7 hz.
Fig 3. 5 inch tertiary move varying kiThr value.
Top plot is vertical drive, bottom is horizontal/tilt. In this example the kiThreshold is varied. The Ki term in the PI loop does not kick in until the position error drops below this value. The two columns of numbers show the Kithr used in inches and encoder counts. The tertiary is setup for KiThr = 500. Increasing Kithr requires more time to come back on position. You would like to keep the value small. Too small and the proportional term may not be strong enough to drive the system by itself.
Fig 3,4. Plot the maximum freq. and amplitude of a sine wave by accTm.Figure 3 is for the vertical drive while figure 4 is the horizontal tilt. If the position is Asin(wt) then the velocity is w*A*cos(wt) and the acceleration is -w^2*A*sin(wt). The maximum velocity is 2 in/sec and 3.5 in/sec for the ver, hor/tilt motors. The acceleration limit is maxVel/acctm. The top plot on each page shows the maximum frequency by maximum requested velocity for different accTm's. The rightmost velocity (2 for the ver) is for 2048 dacCnts. If we limit the system to 1024 dacCnts then we use the 3rd point from the left.
The lower plot shows the maximum sine wave amplitude versus requested velocity for various accTm's. These amplitudes are at the maximum allowable frequency.processing: ter/sim/dosim.pro
The motors on cover most of the band with the 2 mhz comb (at about 2% tsys). The 25 Mhz comb is about 10% of Tsys. The 8 Mhz comb with the motors off ranges from 2 to 8% tsys.
02aug01 plot of digital box on,off. Data was taken for 60 seconds with the motors off, digital box2 on. Then 60 seconds with everything off. The plot shows the strength of the signal as a fraction of Tsys. It is averaged over the 60 seconds. There is an 8 Mhz comb (marked with the green *). It gets to about 8% of tsys. This is about 20db higher than the noise for a 60 second 25Khz integration. The black line is pol A and the the red line is pol B. 08aug01 motors on, motors off, all off cycle (image 2.9 mb). Pol A was used for the image. It has 60 seconds motors on, 60 seconds motors off, then 60 seconds all off. This cycle was repeated twice (the cycle starts from the bottom of each plot). Horizontal lines were drawn at the transitions. The image was normalized by the average "all off " bandpass. It was also flattened in the time direction by averaging a set of frequency channels and then dividing this time series into all frequency channels (this is why the motor on birdies have some negative going regions).The motors have a large spike every 25 Mhz (the dsp chip in the amplifier runs at 25 Mhz). You can also see a comb at 2 Mhz (the wavey line are some new cameras mounted on the service platform.) 08aug01 motors on,motors off average plot. This plot averages the motors on (black line), and motors off (red line) (pol A). They were normalized to "all off" so the units are Tsys (28 K for lbn). The birdies at 1366-1368 is a radar. The birdie at 1420 is the galaxy.
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