Motor Master 5000 - rpm, thrust, power, etc. meter and tester - Discussions

OK, so I finally got sick of testing my motors/esc/props on make-shift test stands. I decided to make something that will be as close to finished product as possible and hopefully, if there is any interest I could make it into an official product.

Without further ado, I present Motor Master 5000 (as in 5000g max thrust). Here are the specs:

1) Max voltage - 28V (0.1V resolution)
2) Max current - 50A (0.01A resolution)
3) Max load - 5000g (1g resolution, ~175oz)
4) Max RPM - 30000 (for measuring performance without the prop)
5) Size - 50 x 35 x 10 cm (LxHxW ~ 20"x14"x4")
6) Weight - 2kg (~ 4lbs)

Right now It's a standalone product and it displays data on the color LCD and also sends data via serial connection to the computer where you can further analyze it.
It sends data in ASCII or binary format (to be interpreted in the client application e.g. Processing which I will post soon too). Here is the sample ASCII output that can be pasted in Excel and then you can do with it as you please.

MotorMaster 5000 ver 1.0.1
VCC[mV] 4935 Cell K 0.186423 Offset 2083.6311 RAM 972
Servo RPM Vb[mV] I[mA] Thr[g] Cell Eff[g/W]
1000 0 11229 0 2.49 2097 0
1000 0 11229 0 2.49 2097 0
1050 382 11200 114 4.17 2106 3.43
1050 410 11200 105 3.98 2105 3.68
1100 804 11200 168 24.49 2215 13.56
1100 813 11200 168 25.42 2220 14.11
1150 1081 11200 265 45.93 2330 15.81
1150 1082 11200 259 46.12 2331 15.91
1200 1362 11168 441 70.16 2460 14.30
1200 1369 11170 413 71.10 2465 15.45
...

I would like it to (eventually) become an open source project but for now I will keep polishing it until it is ready for "public scrutiny"

Here are some pictures (sorry for the lighting) and I will soon be posting more and some videos too.

Oh and yeah, good news is it's also an Arduino! (Pro Mini which was even cheaper than the ATMega328p chip and you can easily replace it or use elsewhere in a dire need)

I'm open for suggestions and comments so please feel free to write.

Cheers,
Misa

Thank you so much Andre for your kind words and advice, and if I may say so it is a great idea. If you can see next to the motor there is an MPU6050 already in place :)

Actually you can't see it there since I couldn't post so many pictures on this forum (limit of 3 to attach I believe), but here is the link to the rcgroups, check the photo #5 (actually I attached it here so take a look).

I am reading vibrations and can predict the imbalance to a certain extent, but there are some issues:

1) RPM reading is optical so I needed to put a tiny (5mm x 8mm) piece of black electrical tape to register. Well that is what is affecting the reading, I seem to detect that tape. Possible solution: black paint which I hope will work.

2) MPU has 1KHz max reading frequency which leaves too few points for the entire turn. Higher sampling rates would be better and interpolation and averaging could probably give good enough results.

For motor balancing I need motor turning at higher speeds and that further reduces number of useful data points.

As far as the client application is concerned I am using Processing and it seems to be able to create executable (I will make the source for it available anyways) as well as the (very simple) serial protocol it uses to communicate with the MM5K.

Anyways, I didn't want to make any promises but am working on it. For now I would like to keep it simple, make a tool that anyone can use, get useful information and not spend too much time building the test stand (as fun as it may be :))

Any further help/advice would be greatly appreciated.

05 ESC and cabling view.JPG

Replies

- - - - Andre K. > Misa Rakic March 18, 2014 at 5:56am
        
        I use a litte magic marker dot for balancing, on motor, or prop. then work from there.
        
        Until it proves to work, it is sufficient to compare vibrations while moving the weight "around the clock" in different positions in respect to the "dot" - I keep the dot up, then place extra weight at "3 ,6, 9 o'clock"
        
        Anyway - the methodology can be adapted, and vibration analysis does not have to be complex from the start - a simple RMS comparsion between runs is very useful too.
        
        Misa Rakic > Andre K. March 18, 2014 at 8:42am
        
        I see. We may have different approaches.
        
        I would like to determine the exact angle X with respect to the starting point (tape in my case) at which the imbalance is located. Then you can put tape to the opposite (X- 180) end and continue doing so until the minimal amplitude is reached. Just moving the tape (3, 6, etc.) is the "cell phone with seismometer app" approach which is something I would like to avoid since all the data necessary is already available.
      - Misa Rakic > Andre K. March 18, 2014 at 3:15am
        
        Yes, I was contemplating making it that way but was concerned about the reading being dependent on prop config (which can be entered through the setup/pc app/terminal) and possibly less accurate reading (shorter time between pulses, greater err). However that all might be worth it if I can't get rid of the tape. I'll give it a shot and see how it works.
- Misa Rakic > Andre K. March 17, 2014 at 5:31pm
  
  Thank you so much Andre for your kind words and advice, and if I may say so it is a great idea. If you can see next to the motor there is an MPU6050 already in place :)
  
  Actually you can't see it there since I couldn't post so many pictures on this forum (limit of 3 to attach I believe), but here is the link to the rcgroups, check the photo #5 (actually I attached it here so take a look).
  
  I am reading vibrations and can predict the imbalance to a certain extent, but there are some issues:
  
  1) RPM reading is optical so I needed to put a tiny (5mm x 8mm) piece of black electrical tape to register. Well that is what is affecting the reading, I seem to detect that tape. Possible solution: black paint which I hope will work.
  
  2) MPU has 1KHz max reading frequency which leaves too few points for the entire turn. Higher sampling rates would be better and interpolation and averaging could probably give good enough results.
  
  For motor balancing I need motor turning at higher speeds and that further reduces number of useful data points.
  
  As far as the client application is concerned I am using Processing and it seems to be able to create executable (I will make the source for it available anyways) as well as the (very simple) serial protocol it uses to communicate with the MM5K.
  
  Anyways, I didn't want to make any promises but am working on it. For now I would like to keep it simple, make a tool that anyone can use, get useful information and not spend too much time building the test stand (as fun as it may be :))
  
  Any further help/advice would be greatly appreciated.
  
  05 ESC and cabling view.JPG
  - Andre K. > Misa Rakic March 17, 2014 at 11:51pm
    
    I wasn't sure if 328p was fast enough, that's why I wrote "attempt to predict" - sure porting to Teensy 3.1 , or using teensyduino would most likely take care of that, (if extra math or extra many samples needed to be compared to get an idea - or faster acc was needed), it also got many more hw interrupts.
    
    regarding optical reading, please don't use the sticker method. a better method would be to hav a IR led pointed at the phototransistor from right above the control panel,
    
    - and the phototransistor (pointed at the diode), should be placed as near the center of the motor as possible , yet making space for those larger motors. - this will give longer "blackout" time even at crazy speeds, and make the counting easier.
    - Misa Rakic > Andre K. March 18, 2014 at 2:20am
      
      The problem is MPU not 328p (at this point). I am reading data at 1KHz (max for MPU) and sending to the PC but at 1KHz.
      
      However, teensy 3/3.1 is great so I am still contemplating having version with that. The limiting factor is that I want the price to be $99 and Teensy is more expensive...
      
      About the IR sensor, not exactly sure I understood, where do you propose I put the IR LED?

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