Thanos AMC1.6 USB 2DOF Motion Controller

[tronicgr]

Glad it works correctly now!

Its bad for all h-bridges to reverse the direction before the motor stops completely. The inertia of the motor generates lots of current that is shorting out the mosfets as they switch to other direction. And there is the problem with normal switching of the mosfets too, that it must not be faster than a certain pulse width. That's why many motor drivers are doing switching up to 95% and then jump to 100%. This avoids the mosfets getting too much hot. The opto-link board does this too, after 95% of the PWM it jumps to 100% speed that is really good feature!

Thanos

[ne02005]

And here is a video with my tests... Full speed, edge to edge and no incorrect rotation! Notice on the video, the dead zone on the end positions of the sensor developed in firmware v1.1e !





Thanos

Hi Thanos, very nice!

Only 90 degree rotation ?

Will be better presition 180 degree?

I see 0 to 255 values. With Pots are 0 to 1024.

How you connect the hall sensor? directly to A1 (feedback encoders)???

thanks

[tronicgr]

It is 90 degree rotation because I placed the magnets a little closer than I thought, plus the 10% deadzone on the edges of the motion range to protect normal potentiometers from mechanical damage.

You can get more that 180 degree rotation using the "AS5145 Automotive Rotary Encoder IC". Its actually a full 360 degree sensor!

In the last firmware I decided to divide the potentiometer readings to match the input positions from the PC, but it still using 1024 values internally for the smoother positioning. It's less confusing this way.

I connect the hall effect sensors in the same ports as the potentiometers. They are analog devices too that output voltage 0-5v. Although you could connect the AS5145 as quadrature encoder in the provided encoder port (not implemented yet as there is no demand).

Thanos

[ne02005]

@ Tonquites
Yes. It just splits the signals to the two pairs of h-bridges. I don't see why its not going to work.

How will be the xsim configuration? with 2 hbridges and 4 wipers?

Thanks

[tronicgr]

It will be still for two axis, but two motors working together for more power. It was done before.

[tonquites]

It will be still for two axis, but two motors working together for more power. It was done before.

I can not wait to be able to ride my my AMC1.6, I just get the card FT232RL, now I'm looking for processor ATMEGA644-20PU, the two H-bridges are already here ready to move the four engines, but will not use them to get stronger, I'll use them to double the speed of the motors.

The only thing that separates me from building AMC1.6, and my wife, who asked that I finished the mechanical part of the simulator so that our house does not look so cluttered with so many pieces throughout the house, hehehe.

hugs
Everton

Portuguese version

Não vejo a hora de poder montar minha a minha AMC1.6, acabei de receber a placa FT232RL, agora estou a procura do processador ATMEGA644-20PU, as duas pontes-H já estão aqui prontas para mover os 4 motores, mas não vou usar-los para obter mais força, vou usa-los para dobrar a velocidade dos motores.

A unica coisa, que me separa da construção da AMC1.6, e minha esposa, que pediu para que eu terminasse a parte mecanica do simulador para que nossa casa não fique tão bagunçada com tantas peças espalhadas pela casa, hehehe.

Abraços
Everton

[vicpopo]

Glad it works correctly now!

Its bad for all h-bridges to reverse the direction before the motor stops completely. The inertia of the motor generates lots of current that is shorting out the mosfets as they switch to other direction. And there is the problem with normal switching of the mosfets too, that it must not be faster than a certain pulse width. That's why many motor drivers are doing switching up to 95% and then jump to 100%. This avoids the mosfets getting too much hot. The opto-link board does this too, after 95% of the PWM it jumps to 100% speed that is really good feature!

Thanos

Hi Thanos ,
My friend told to me in this case ,the best solution is to put more transistors in paralel for sharing all this high current!
He said too that he often puts a varistor between the motor phases for absorbing this current.
In the forum I saw a h-bridge with more dc12volts motors from Speedy ?
Link : http://www.x-sim.de/forum/viewtopic.php?f=43&t=246#p1344
Did you think that this h-bridge could be a solution for bigger dc motors as wiper motors

[tronicgr]

Yes, this is another h-bridge that is more expensive since its using specialized IC for the switching of the mosfets. But its more strong as it uses more mosfets per channel. Mind that this board is only for one motor!! And yes it will be able to handle 180W DC motors like the ones you have.

My h-bridge was designed for use with low power wiper motors, that's why I recommend in the fist page of the amc1.6 project that a better solution for other DC motors would be using the Pololu High Power Motor drivers that I verified them working well under higher loads up to 25A. If you take a closer look at them they are using almost the same technology like "Speedy's" design with double mosfets.

Pololu 18v25.jpg (56.59 KiB) Viewed 7015 times

Thanos

[vicpopo]

My h-bridge was designed for use with low power wiper motors, that's why I recommend in the fist page of the amc1.6 project that a better solution for other DC motors would be using the Pololu High Power Motor drivers that I verified them working well under higher loads up to 25A. If you take a closer look at them they are using almost the same technology like "Speedy's" design with double mosfets.

Pololu 18v25.jpg

Thanos

Hi Thanos,
Did the pololu support high current peak ?I couldn't put a ampermeter already on the circuit , but when I look at what's happening unloaded ,I can suppose that in inversion direction in full load ,the current could be very high!
Regards
Gilles
In fact there are the same motors as Floriske
http://www.x-sim.de/forum/viewtopic.php?f=37&t=129#p797

[tronicgr]

Hi Gilles,

The pololu site says: "The motor driver can tolerate peak currents in excess of 200 A, and the continuous rating is 25 A"

I had ammeter connected on my sim before, and the max current that was passing from the battery cable that was providing power for both wiper motors was averaging around 10A with 20A peaks.

Watch my old video where I had my DSMhb1.2 on my sim with me on it (90kg): http://www.youtube.com/watch?v=WVItAoPYUtI
Pay attention on the minute 1.30 that you can see the ammeter (the bottom gauge). Its range was up to 30A, never reached it.

Oh, and the temperature sensor on the mosfets... only 2 degrees over the room temperature!! 24 degrees Celsius.

Thanos