Thanos AMC1.6 USB 2DOF Motion Controller

[vicpopo]

I can't measure no resistance ! That means that the insulation is good.I tested a 10 kOhm multi turn pot and my multimeter measured around 10kOhm.I tried all scales and I measured anything between power cables and the housing.
The motors are for golf trolley applications , rpm 3600 rpm gear ratio 25 , 180 Watt.Reference is RP-Q-180

No, I don't mean between the housing and the cables, but measure the resistance between the two cables!!! The motor's coil must have a resistance right? For example the resistance for my wiper motor is 3 Ohm.

Ok, doing some calculations on the specifications of your motor I got figured out that most likely your motor's resistance is 0.8 Ohm (or 15A at 12V), that is quite low and almost the same as the IRF3205 RON resistance! But with VGS at 5V you will get only 12A power at room temperature (25 degrees Celsius). Then because of the low resistance the temperature of the mosfets junction rises up to 175 degrees Celsius to cope with the 15A demand.

One work-around would be to use the IRLZ44 in your case. Their RON resistance is about 0.028 Ohm

Personally I never had problems like that with my h-bridges, I was always using IRFZ44 and IRF3205 with no too much overheating, and never burn any mosfets! Maybe your h-bridge bottom needs to be cleaned for solder residue and then cover it with plastic coating. That's what I always do on all my boards.

Thanos

Hi Thanos ,
For bigworm motor I measured 6 Ohm and I measured on a wiper motor 1 Ohm.
PSU : Chinese PSU 12V 30 A
Gilles

[tronicgr]

Only 6 Ohm?? wow! You should connect and multimeter in series to the motor and measure the Ampere when you power it. From the calculations I get only 2A current! That should not be enough for the motor to rotate properly (only 24W!!!)

[tronicgr]

I checked the voltage p1d1 ( the same for all directions signals) and I measured that the voltage is changing (from 5v to 0) when the slider (test plugin mode effect 21 with Xsim) come truth middle course from the slider ( middle axis ,value 127).
In my mind when I move the slider up and down ,the voltage is changing when you inverse the direction of the slider! For exemple, I tested changing the slider in a half axis way ( 0-127 or 127-255) but the p1d1 had the same voltage eventhought I moved it up and down in half axis way!Do I clear for my desciption and does it normal ?

Fixed now!!! Thanks for the feedback, it was a forgotten assignment from the old AMC1.5 instead of the correct pin in the new board.

I replaced the firmware on the main page with the fix. Download it and load it again.

[vicpopo]

I checked the voltage p1d1 ( the same for all directions signals) and I measured that the voltage is changing (from 5v to 0) when the slider (test plugin mode effect 21 with Xsim) come truth middle course from the slider ( middle axis ,value 127).
In my mind when I move the slider up and down ,the voltage is changing when you inverse the direction of the slider! For exemple, I tested changing the slider in a half axis way ( 0-127 or 127-255) but the p1d1 had the same voltage eventhought I moved it up and down in half axis way!Do I clear for my desciption and does it normal ?

Fixed now!!! Thanks for the feedback, it was a forgotten assignment from the old AMC1.5 instead of the correct pin in the new board.

I replaced the firmware on the main page with the fix. Download it and load it again.

Hi Thanos,
I will try as soon as possible and I will try testing the start current for the 2 motors ,bigworm and wiper motor.
I can make some measurements with a oscilloscope if you want!You just have to tell me where put the cables , because I'm not sure and I don't want to burn it like my transistors
I would like to mesure what happen on the motor connection but I'm not really sure where connect the cables: from ground to one motor power cable or directly between the power cable!
I'm happy helping your job for the amc1.6!
Did you see the video on youtube I linked to you(asynchronus motor + inverter).I will probably open a new post reporting for this project, if I can take some time!
Gilles

[tronicgr]

Well, measuring the h-bridge with oscilloscope is a little tricky because the two motor power connectors are shifting polarity and you will not really see much. You can try capturing the signals in the four outputs of the 74HC08 chip to make sure they pass the PWM signal. I don't have any of my old h-bridges anymore to test them myself with my analog/digital oscilloscope.

If you insist measuring the output of the h-bridge, make sure you have 10x probe and you connect the ground alligator clip on the power ground input of the h-bridge and the probe nose to one of the outputs (where you attach the motor). Measure one output at a time.

[vicpopo]

Only 6 Ohm?? wow! You should connect and multimeter in series to the motor and measure the Ampere when you power it. From the calculations I get only 2A current! That should not be enough for the motor to rotate properly (only 24W!!!)

Hi ,
I measured the load current and for both motors that is 1.8 A ,when I try to stop shaft with my hand I reached 5 A.
The PSU seems to be OK!
If I could this evening I will test one more time the both motors with h-bridge and amc1.6 and keep in touch.
Gilles

[vicpopo]

Hi Thanos ,
I made a new test with a wiper motor.The result is the same , the motor is shaking trembling and it doesn't work very well.
As I said to you the PSU seems to be ok because when I connect it directly to the motor it runs well.
One think peharps a little bit surprizing! When I power on the PSU and without Xsim's runing the motor is shaking and the both leds is flashing as like as it tries holding a position.
For me until Xsim's runing the motor shouldn't be loaded by any voltage!
I confirm that the voltage is too low and I agree with you that the the reasons the motor's trembling.
When all the tests I could made with the slider in auto mode in test tablet or with my hand up and down ,I never had a voltage bigger than 4 volt.Once the motor's running continuisely and the voltage was 6 volts.
One finally think which for me is not normal or normal ,when I reach the position 255 for the axis the motor stoped and the pot position is 1023.I couldn't reach the position 0 because the pot reach never 0 (ss490)!
What is sure is like you thought the voltage is not enough to have a good positioning and dynamics but I don't know why ?
I checked the PSU on the h bridge and I 've got 12volts!
A little video
Regards
Gilles

[ne02005]

Congratulations Thanos!!!

I´ve just order the Sparkfun USB module to cbuild your new AMC, (I got an Amc 1.5).

I see you are recomend Pololu High-Power Motor Driver 18v25. Is better than your H-Bridge?

I´m waiting your answer to order at Pololu.

Thanks

ne02005

[vicpopo]

Hi Thanos,

Test amc1.6 + h-bridge : that looks better because I made a mistake I suppose.I was using pwm2 ( the simple h-bridge not burned ) and the pot ss490 was on pot1 in amc1.6!The second mistake is that I replaced e the 74CHO8 ,thinking it was burned, by a not good one.I replace it and it works better.
I tested the voltage and now I can reach 12v in the h-bridge which powered the motor.The only think I don't understand is that the motor is shaking , trembling all the time between differents positioning and I can't stop that.
Do you think this problems come for grounding ?

I posted 2 videos below.

When I move the slider manual he looks dynamic.The only disturbing effect is when positioning is over , motor turn until he found the right position but one turn after!You linked me a video showing the protection for this problems with switchers.that is the solution I suppose.

Kp setting : I tried with an another PC and the problem is always here.You can change the Kp setting but it takes time, you have to make several tries for entering new values.

Regards

Gilles

Video 1 :
Video 2 :

[tronicgr]

Hi Gilles,

I think the shaking is coming from the SS490 sensor trying to hold position. But its amplified because of poor cable shielding or too little range in the ADC range. Try to use full ADC range first (turn trim potentiometer all the way clockwise until you hear it clicking).

http://motionsim.blogspot.com/2012/06/s ... nsors.html


About the KP settings I seen that problem too, I'll try to address is as soon is possible.

Thanos