outrunner motor RPM / KV?

Sorry that my description was not clear enough. I did connect the Simonk 20A ESC to the 12V/150W transformer. Then I used ESC tester to start the propeller and control its speed. Voltmeter did show 12.2V always. What changed was what amperemeter showed for different speeds selected by ESC tester:

Now I did measure again with laser tachometer for 12.2V/2.01A showing of voltmeter+amperemeter. It did show 7635rpm (I must have had more amps in measurement of previous posting).

Then I did place Raspberry v2 NoIR camera (with added M12 mount and M12 lens) above the scene. I tried my 48led IR light and it was good enough to light the scene for capturing with 50µs shutter time (1000lm lamp was not sufficient). https://www.aliexpress.com/item/32856122386.html |500x375

This was command used to capture 150fps video with 50µs shutter time after propeller was rotating with 12.2V and 2.01A:

$ raspivid -md 7 -w 640 -h 480 -p 22,50,640,480 -t 0 -fps 150 --shutter 50 -o tst.h264 -pts tst.pts

After aborting the recording I did run ptsanalyze tool on generated tst.pts timestamp file. It reported "535 frames were captured at 150fps" with no frame skips.

Finally I extracted frames from the video and created a 13 frame 2fps animation from the repeating pattern found: |500x375

The propeller is rotating clockwise, and it has three blades, with one blade having reflective material. The video is taken at 150fps framerate, and would stand still for exactly 9000rpm speed. But what you can see is that propller reflective blade always does a little less than one full round. If you follow the animation you will see that it looses 2 rounds per 13 frames. Total rpm less than 9000rpm is therefore 150/13*2*60=1385, resulting in 9000-1385=7615rpm.

This is nearly a perfect match for the 7635rpm measured with laser tachometer!

P.S: The video frames show crazy rolling shutter effect of rotating blades. I did take similar video of a mini drone propeller rotation with 26000rpm. I used my technique to make Raspberry v1 camera capture global shutter frames. This video of fast rotating propeller looks much nicer: https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter |500x281

I did measurements with ESC tester setting speed resulting in 1-10A in 1A steps, and a final measurement at 12.5A (outside of amperemeter 0-10A range). Looks quite good, nearly a straight line:

Voltage[V] Current[A] R.s.[rpm]
12.2       1          4791
12.2       2          7635
12.1       3          8652
12.0       4          9842
11.9       5          10883
11.8       6          11518
11.8       7          12740
11.7       8          13384
11.6       9          13871
11.5       10.1       14438
11.4       12.5       15321

I did take video of 10A measurement, it is so loud! https://www.youtube.com/watch?v=sKkpkJijsTQ |500x370

With 12.5A there is air to 20A the Simonk ESC can handle (I did order Simonk 30A ESCs as well). I ordered a new volt-/ampere-meter with 0-100V/0-50A that should arrive on Monday for >12.5A experiments.

What does the fastest measurement mean? New speed record at blade tip, 101.9m/s or 367km/h:

$ echo "pi=4*a(1); scale=2; 0.127*pi*15321/60" | bc -ql
101.88
$ echo "pi=4*a(1); scale=2; 0.127*pi*15321/60*3.6" | bc -ql
366.76
$

I did capture below 20000eps multiple exposure frame with 43 markers and created 20000fps video from it. The speed at 34mm diameter propeller blade tip was "only" 49.7m/s. Now 101.9m/s should allow for 40000eps multiple exposure, and since markers will be 63.5mm away from center compared to 17mm, much more markers should be convertible to a video, maybe first 50000fps video with Raspberry v1 camera. Before trying that lets see whether more than 101.9m/s can be done ... |500x281

HermannSW: With 12.5A there is air to 20A the Simonk ESC can handle (I did order Simonk 30A ESCs as well).

Not that much air, should not go above 18.5A, from A2212 KV2700 spec at start of this thread:

Load current: 18.5A
Power (Watt): 240
ESC(A): 30A,20A
Peak.Amps :14-22 A

For non-peak run 18.5A at 240W translates to 240W/18.5A=13V.

P.S: Update on speed sources at home currently for high speed global shutter experiments:

  • 36.3m/s airsoft pistol pellet
  • 63.8m/s at blade tip of 1S mini drone propeller, overpowered with 4.3V
  • 101.9m/s at blade tip of (11.4V/12.5A) outrunner motor propeller
  • 109.2m/s airgun pellet

P.P.S: Just ordered AC 110 V/220 V to DC 12 V 20 A 240 W Power Supply to go higher than 12.5A, should arrive on Friday ...

slipstick: Or if you are using a prop make sure you get the lowest pitch (second number in the spec) you can find. A 120 x 30 prop takes noticeably less power than a 120 x 75 prop.

I tried 2nd propeller today, with two blades, and same pitch: |500x323

I determined the values for 1-10A again in 1A steps. While this propeller rotated faster for each speed set by ESC tester, it produced much more vibrations. I was not able to get a laser tachometer reading for 12.5A because always the black tape seperates from blade, see magnification top right. These are the rpm values determined:

7011
9773
11801
13379
14640
15649
16470
17240
17611
18320

A picture says more than 1000 words, here is the diagram: |500x333

New speed record at blade tip, 121.8m/s or 439km/h:

$ echo "pi=4*a(1); scale=2; 0.127*pi*18320/60" | bc -ql
121.82
$ echo "pi=4*a(1); scale=2; 0.127*pi*18320/60*3.6" | bc -ql
438.55
$

The outrunner motor gets quite hot, but the problem is Simonk ESC gets hot as well running at 10A. Not sure how long it would work without dying, but I will not try out now.

Running with more than 10A is beyond what used amperemeter/voltmeter can handle (will get 0-100V/0-50A on weekend), and at the edge of what the 12V/150W transformer can deliver (12V/240W transformer will arrive Friday).

Since pitch and diameter are identical for 3-blade and 2-blade propeller, it seems the blade missing for 2-blade propeller makes the difference, less air needs to be pushed away.

Yes 3-blade props need more power than equivalent 2-blade props, that's very well known. It's roughly 10% more for the same rpm for 3 blades, 15% more for a 4 blade prop. And yes it is because more blades move more air.

Steve

HermannSW: The outrunner motor gets quite hot, but the problem is Simonk ESC gets hot as well running at 10A. Not sure how long it would work without dying, but I will not try out now.

There are online calculators for matching motor, prop and rpm. Very good advice to use them...

The motor is presumed to be air-cooled in the prop-wash, otherwise you'll need to de-rate it substantially.

slipstick: Yes 3-blade props need more power than equivalent 2-blade props, that's very well known. It's roughly 10% more for the same rpm for 3 blades, 15% more for a 4 blade prop.

Interesting, I assume you mean watts with "power". The voltage dropped slowly below 12V for both blades, so watts is roughly proportional to amps. 3-blade 13384rpm needed 9A, 2-blade 13379rpm needed 5A, and that is 80% more for 3-blade than 2-blade. I assume that this is caused by my testing setup, although propeller is more than 8cm above ground, the ground will affect the propellers.

MarkT: The motor is presumed to be air-cooled in the prop-wash, otherwise you'll need to de-rate it substantially.

That is true, I did some measurements and then paused to give the motor time to cool down. And not only the motor, Simonk ESC became hot as well. For my application the motor does not need to run long though. I will paint the propeller black besides a small area at blade tip and then do single digit microsecond flashes at more than 20KHz frequence to get multiple exposure global shutter frames. I did 20KHz already allowing to create first 20000fps Raspberry v1 camera slow-mo, and I will be able to do 50000eps (exposures per second) by the speeds seen here already. And yes, this is a specialized "misuse" of outrunner motor with propeller.

slipstick: The pitch/twist of the propeller adds to the power it takes and so the amount it slows the motor down. Or if you are using a prop make sure you get the lowest pitch (second number in the spec) you can find.

Thank you Steve for that hint. I saw that reducing blade count from 3 to 2 made a difference. Now following your "lowest pitch" guidance I ended up with the minimum possible, "1 blade with 0 pitch"! I did cut out a thin circular disk (123mm diameter) from blue cardboard. I did press 4 layers of that cardboard together and measured 1mm thickness. And I added the reflective marker for laser tachometer measurements. Luckily the blue was dark enough to allow for successful speed determination: |500x375

As you can see in the photo I did place Raspberry v2 NoIR camera again to capture a 150fps video of fast rotating circular disk. Scene is again lit by 48led 12V light from top, and like before I captured with only 50µs shutter time to get clear frames. They suffer from rolling shutter effect, though. Here you can see circular disk slowly rotating, animation played at 5fps, 30× slower than real. Look at top right outrunner motor bullet, it absolutely keeps in place. The nearly quadratic reflective marker turned out to be not reflective for IR light: |500x375

Here you can see a run powered with 12V/6A, slightly more than 17000rpm or nearly 300 rotations per second, with 123mm diameter more than 100m/s speed! Because of the high speed and v2 camera rolling shutter effect the reflective marker now looks like a thin line. And the outrunner motor bullet heavily shakes. Again animation plays at 5fps, 30× slower than real: |500x375

Finally I did measure between 1A and 10A again for circular disk. I did leave out 8A and 9A because I am really happy with 10A rpm reading, and because of the stress those runs are for Simonk ESC that gets hot:

Current[A] 3-blade 2-blade disk
12.5       15321
10         14438   18320   21591
9          13871   17611 
8          13384   17240 
7          12740   16470   18736
6          11518   15649   17451
5          10883   14640   16105
4          9842    13379   14604
3          8652    11801   12993
2          7635    9773    10992
1          4791    7011    7480

Here is the updated diagram -- I will not even look at propellers anymore for my high rotational speed experiments, 0-pitch circular disk is the way to go for highest speeds: |500x276

New speed record achieved again with 21591rpm for 12V/10A, 139m/s(!) or 501km/h(!!):

$ echo "pi=4*a(1); scale=2; 0.123*pi*21591/60" | bc -ql
139.05
$ echo "pi=4*a(1); scale=2; 0.123*pi*21591/60*3.6" | bc -ql
500.58
$

I was first surprised that the thin cardboard could stand the massive forces, the disk rotates with 360 rotations per second.

I was surprised as well that the imbalance shown in the fast rotating animation did not do harm to the disk and just works. As you can see in the animation the line and dot that can be seen on motor test station ground plate in lower left remain completely in place. Only the 6cm high wooden bar superglued onto ground plate, the outrunner motor is firmly screwed into, shakes.

With new 240W transformer and new 50A digital amperemeter on weekend more amps tests can be done to see where the speed limit might be. And I already did draw a 160mm diameter circle on the remaining piece of blue cardboard I have, need to cut that out and see what rpms and tip speeds can be achieved with 10A for that disk ...

P.S: The 123mm diameter blue cardboard disk with reflective marker does weigh 1.6g, the 160mm diameter disk with reflective marker does weigh 2.8g

Finally I was able to go even beyond V*KV ...

First I did try with 160mm diameter disk. That was a flop, compared to 123-disk -36% rpm and -17% disk edge speed.

Because of that I went into the other direction, 88-disk with 88mm diameter: |500x375

First test with only speed showing 3A did immediately show >20000rpm. Next test with 7A did show >30000rpm. And finally turning ESC tester knob to maximal position resulted in >33000rpm! I captured photo of amperemeter/voltmeter at maximal speed: |500x375

Doing the V*KV math gives 11.7V*2700KV=31590rpm -- that is 2000rpm less than the measured 33533rpm! Here are all values:

Current[A] 3-blade 2-blade 123-disk 160-disk 88-disk
12.5       15321
10         14438   18320   21591    13742
9          13871   17611                     33533
8          13384   17240 
7          12740   16470   18736             30240
6          11518   15649   17451
5          10883   14640   16105
4          9842    13379   14604
3          8652    11801   12993    8744     20163
2          7635    9773    10992
1          4791    7011    7480

New speed record with 33533rpm 88-disk, 154.5m/s or 556km/h:

pi@raspberrypi4B:~ $ echo "pi=4*a(1); scale=2; 0.088*pi*33533/60" | bc -ql
154.50
pi@raspberrypi4B:~ $ echo "pi=4*a(1); scale=2; 0.088*pi*33533/60*3.6" | bc -ql
556.20
pi@raspberrypi4B:~ $

Here is updated diagram, since 88-disk maxed out already, next experiments will be 123-disk with 240W transformer that just arrived for ESC tester speeds with >10A. If that does not top 154.5m/s, other diameters between 88mm and 123mm can be tried out ... |500x278

I did upload 150fps slowmo of 33533rpm run to youtube, and that shows only minimal movements of outrunner motor bullet top: https://www.youtube.com/watch?v=Spu8OzF8xrc&feature=youtu.be |500x378

I remembered that I have two v1 cameras installed at different side borders inside motor test station. I replaced the camera on front inside by a v1 NoIR camera after I realized that the camera lens was exactly on height of circular disk on outrunner motor. I typically place Pi ZeroW outside before motor test station to allow capturing when needed. Its camera cable connects to a Raspberry camera cable adapter (left of ESC tester that controls the outrunner motor) that is connected to v1 NoIR camera on the inside: |500x375

I took a raspivid video with 50µs shutter time again, this time with 90fps framerate because that is the maximal v1 camera framerate. I powered the outrunner motor with ESC tester from stand still to maximal speed of 559rps, kept that for 10s and then slowed down to stand still. With 559rps, a full rotation takes slightly less than 2ms, and circular disk does slightly more than 6 rotations between successive frames. I did capture timestamps, and did run ptsanalyze just on the 99 successive frames in the middle of high speed phase used to create below animation, covering 1.1s of the video. No frame skips, and all frame deltas in 10µs wide band:

pi@raspberrypi08X:~ $ ./ptsanalyze x.pts 0
creating tstamps.csv
99 frames were captured at 90fps
frame delta time[us] distribution
      1 11086
      3 11088
     10 11089
     32 11090
     23 11091
     10 11092
     13 11093
      3 11094
      1 11096
after skip frame indices (middle column)
0 frame skips (0%)
pi@raspberrypi08X:~ $

The animation is played at 3fps, 30× slower than real. Because the frames were nearly completely dark I took a raspistill image with same 48led infrared lighting used to record the video. Room window shutter was closed, room completly dark. I did cut out the active part from the frames and did overlay onto the raspistill image, and created animated .gif from that (only 260KB size). What you can see is that outrunner motor bullet keeps its position completely despite rotation with >150m/s. What I find interesting is that the circular cardboard seems to be not that flat as I would have thought. Forum software scales the animation down a bit, right click in order to see it at original 640x480 size: |500x375

Wow, I did capture 100fps video of laser tachometer and did turn ESC tester speed knob from off to full in less than a second with 88-disk. No frame skips, frame deltas are in range 9943..9998µs. The resultig g-force is really cool. First non-0 reading is 65rpm which is 1km/h. I treat this as "0", and next reading 23779rpm is shown after only 0.92s. Acceleration is 119.44 m/s² or more than 12g(!): |500x109

Here are the frames: |500x375

|500x375

|500x375

|500x375

|500x375

P.S: Maintenance work in motor test station: 0-100V/0-10A voltmeter+amperemeter ⇨ 0-100V/0-50A with shunt (ohmmeter says 00.7Ω) 12V/150W transformer ⇨ 12V/240W thin 6cm high wooden bar ⇨ thick 18cm (countermeasure to vibrations above 600km/h for 123-disk) |500x375

Maintenance work done:

  • 0-100V/0-50A ammeter with shunt
  • 12V/240W transformer
  • outrunner motor screwed onto thick 18cm high wooden bar (countermeasure to vibrations above 600km/h)
  • bullet top only 0.5cm below plexiglass
  • aluminum U-profile superglued under plexiglass to avoid plexiglass sag (not my idea, a friend told me to do so on hiking tour)

|500x375

I did measure 1A-7A in 1A steps for 123-disk again. Since start voltage is 12.9V now instead of 12.0V (both dropping with more amps), measured rpm values were roughly 1000 higher than powered with 150W transformer.

I took video of ammeter and sound is loud, you can hear also the loss of 123-disk due to unbalance: https://www.youtube.com/watch?v=RcfZqviNnOs&feature=youtu.be

The ammeter display is not totally clear, but I single stepped through phase with maximal ampere, and I think it was 12V/19A. It all happend quickly, but I think I did read 29xyz on laser tachometer. That means 187m/s or 672km/h at least with (now dead) 123-disk:

$ echo "pi=4*a(1); scale=2; 0.123*pi*29000/60" | bc -ql
186.76
$ echo "pi=4*a(1); scale=2; 0.123*pi*29000/60*3.6" | bc -ql
672.33
$

I will try again with thin cardboard, but maybe a thin firm solid material would be better ... |500x375

I did ask my son to 3D print 0.6mm and 1mm thick 100mm diameter disk with centered 3.17mm hole for outrunner motor shaft. This should allow for stable 622km/h edge speed:

$ echo "pi=4*a(1); scale=2; 0.100*pi*33000/60" | bc -ql
172.78
$ echo "pi=4*a(1); scale=2; 0.100*pi*33000/60*3.6" | bc -ql
622.00
$

The 1mm thick print is ongoing right now. |500x425

Today I learned much on 3D construction without installing any software, export as .stl file, online viewing the .stl file and that treatstock.com allows to upload self made or downloaded from thingverse.com .stl files and give cheap quotes for print+deliver from 3D-shops. Find details in this posting: https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=253300&p=1546345#p1546345 |500x207

HermannSW: I was first surprised that the thin cardboard could stand the massive forces, the disk rotates with 360 rotations per second.

You'd be less suprised if I called it an advanced lightweight biopolymer aligned-fibre composite material.

The acceleration of the edge of a disc is rw^2 where r is the radius in metres, w is the angular velocity in radians/second. 360rps = 2250 rad/s, with a disc of radius 5cm that's an acceleration of 0.05 * 2250^2 = 250000 m/s^2.

The low mass means the forces are a lot less than for a metal disc, which is just as well, but yes its impressive what cardboard can take.

MarkT: You'd be less suprised if I called it an advanced lightweight biopolymer aligned-fibre composite material.

Sure, if you name it that way it sounds better.

My wife and I visited our son Robert today in his University city Karlsruhe, and he gave me the two 100mm diameter disks he did 3D print for me. He used PETG, and print layer height was 0.2mm. Requested heights were 0.6mm and 1.0mm, I just measured and effective heights are 0.65mm and 1.1mm. I did weigh 5.8g and 9.8g for the disks (the lost 123mm cardboard disk did weigh 1.8g).

There were two communication errors.

First I did request centered hole of 3.17mm diameter (A2212 motor shaft diameter), but my son did understand 2.17mm diameter and that is what I got.

Second I did completely forgot on the bullet construction that is on top of A2212 motor shaft. I did measure outer diameter of the screw thread as 4.85mm, and that is what I would have to put the disks over per the original plan: |500x375

These are the two disks, the left 1mm disk with print top side up with a few irregularities, the right 0.6mm height disk with print bottom side up, which has a nicer look (right click, open 5MP photo in new tab and zoom in for details): |500x375

I thought that 1mm diameter difference might be doable to correct by using a bit of force, and I was right. I was able to just put both disks with 2.17mm hole over the 3.17mm diameter motor shaft directly. Because of the diameter mismatch the disk sits firm on motor shaft: |500x375

I did a fist test run with the 1mm disk with reflective marker added. It is really late here and I did not want to turn the motor on that loud. So I did a minimal test run with minimal speed, showing 0.5A only and I measured 8471rpm. It looks as if the firm mount by diameter mismatch seems to be enough, and the bullet construction might not be needed on top of motor shaft. I will see by tests tomorrow.

Not a good idea. It started with reflective marker disconnecting from the disk at 14000rpm. I did superglue it to disk, and that was better. But in next run the disk went up (left motor shaft) roughly at 20000rpm (something above 5A) and that was a good justification to always do runs with plexiglas on top closed. To my surprise the disk did rotate under the plexiglass, without falling down. It did so for say 25 seconds, moving around slightly under plexiglass, before rotation became too slow to keep it up, and then disk did fall down. Sadly I was not quick enough to capture this in a video. Next I will have to fit the center hole of a disk to the propeller bullet construction on top of motor shaft.

P.S: Just noticed that the high rotation speed disk under plexiglass did leave permanent impression to plexiglass: |500x375

I did more tests with the 1.1mm thick 100mm diameter 3D printed disk. Vibrations at 12V/18A were just too big to go further and see an improvement. So I switched to 0.65mm thick 100mm diameter 3D printed disk. While that disk did weigh only 5.8g instead of 9.8g, the vibrations were too big. Only seconds after above 18A motor/ESC degradation kicked in.

So I stopped trying to use 3D printed disks, they produce too much vibrations and cannot be handled, most likely because that are too heavy compared to 0.9g of cardboard 88-disk.

Next I did test cardboard 88-disk again and achieved above 33000rpm without issues.

Then I did cut a 100mm diameter disk out from new cardboard I have bought, of 1.0g weight. In a first run I read 29900rpm on laser tachometer, with 12.4V/12.2A shown on volt+amperemeter (captured on smartphone video). On second attempt (after cooling down) the disk got teared to tatters like the 123-disk before. So cardboard 100-disk is no option either.

This thread is basically on the "faster" part of "faster, higher, further", and 3D printed and 100-disk turned out to be dead ends.

So next I tried to get more voltage (because "rpm=KV*V"). After I discussed with a colleague that it is really safe to use both 12V (150W and 240W) transformers in series (only the DC parts, like batteries in series) I did the cabling and now I have 24.9V up to 12.5A (the lower transformer limit): |500x375

In a first run I did measure 36036rpm(!), and from smartphone video of volt+amperemeter I know that was at 24.2V/12.0A. So got new speed record of 165.9m/s or 597km/h:

$ echo "pi=4*a(1); scale=2; 0.088*pi*36016/60" | bc -ql
165.94
$ echo "pi=4*a(1); scale=2; 0.088*pi*36016/60*3.6" | bc -ql
597.38
$

P.S: On second run with rpm reading just above 34000, crazy sound happened and I turned the Simonk ESC knob to off. Motor and ESC were hot typically. Not powering off the ESC completely (volt+amperemeter showed 24.9V/0.0A) after some time I heard a big bang inside motor test station. I have lost Simonk ESCs in the past, but they died silently. This is ESC after big bang: |500x375

After powering off, I powered on again and was surprised to here the typical ESC audio startup sequence. Despite the photo, might the ESC still work after big bang? I did try and really the disk started to move for parts of a second, but then the ESC did die completely.

P.P.S: The three cheap Simonk ESCs ordered on aliexpress.com have not arrived yet. But ESC ordered on amazon will arrive tomorrow.

I ordered another 12V 240W transformer as well, will arrive on Thursday (17.50$). Two 12V 240W transformers in series will allow for 24V/20A tests. (88-disk with 11.7V/8.87A allowed for 154.5m/s, perhaps 24V and up to 20A will allow for double that speed ...)

I did some calculations on next milestone for high framerate slowmo creation, and realized that yesterday's results are near already. I don't need doubling of speed (although seeing >1000km/h at home would be cool). Last run yesterday had 36036rpm or 600rps. For capturing 100,000fps slowmo with 2mm distance between flash markers on edge of disk can be done whenever 24V/20A experiments (which can be done on delivery of 2nd 12V/240W transformer tomorrow) exceed 723rps -- not that much that is missing ... https://www.raspberrypi.org/forums/viewtopic.php?f=43&t=241418&p=1549204#p1549204

New ESC arrived today (right), the left ESC is the exploded one from yesterday: |500x375

New transformer arrived on Thursday, but only a 5V/20A transformer. I looked into my ordering details on Amazon, and indeed I ordered the wrong transformer (20A and same price, did not verify the 12V). First I did want to return the 5V/20A one, but then cancelled that. Reason is, that with one 5A/20A and two 12V/20A transformers I can get 5V/12V/17V/24V/29V by using 1-3 in series. This matches roughly the 0-31V range of my constant voltage/constant current power supply: https://www.raspberrypi.org/forums/viewtopic.php?p=1432400 But that can deliver 5A only, whereas the above voltages allow for 20A. I got the three transformers for 17.50$ each, 52.50$ in total. An adjustable voltage+current power supply that can deliver 20A does cost more than 100$.

Yesterday evening the new (second) 12V/20A transformer arrived, too late for loud experiments for new 88-disk speed record. Also on Sunday I want to avoid that loud noise, work on something funny with silent servos now (PT camera system [and 4DoF robot arm]): https://www.raspberrypi.org/forums/viewtopic.php?f=37&t=254180

P.S: I bought thicker cardboard as well, 0.2mm instead of 0.15mm, perhaps that will allow for more than 88m diameter runs without tearing to tatters. Also the three 3$/pc Simonk ESCs from aliexpress.com arrived -- and those are the 30A version, maybe will help a bit, the 20A versions I used sofar got quite hot.

P.P.S: Learned a lot on servo control ... https://github.com/Hermann-SW/4DoF_robot_arm#4dof-robot-arm

P.P.P.S: Made good progress on on the fly video stream frame analysis, in the animation you see that heuristic did correctly identified the airplane by the 2x2 white marker added to each frame: https://www.raspberrypi.org/forums/viewtopic.php?f=37&t=252272&p=1558081#p1558081 |500x375

Later the PT camera servos will be controlled and frame will not be modified, for always centered video of passing airplane: |500x411