Thanos AMC1.6 USB 2DOF Motion Controller

[jsmith2307]

Greetings,
I am still working the kinks out of my joyrider.
In an effort to cut my loses on Pololu High Power Motor Divers 24V23, yes I smoked two more of them this past week, I’m redoing my set up. First I’m relocating the AVR 1.6, from the tabletop next to my computers to the joyrider simulator, underneath the seat reducing the length of my leads going to the batteries, and the OUTA and OUTB leads that go to the motors. I Reduced the length of my wiring on the bank (rear) side by about 3 feet. And I want to relocate the whole High Power Motor Diver 24V23 packet heat sink and fan to the front end of the joyrider to reduce the length of the leads going to that motor. I figure I could lose 3 to 4 feet doing so! The question I have is: is there a limit of how long the leads going to PWM, DIR, and Gnd are? I’ve also reduced the voltage from 24 volts to 12 volts. Do you have any negative or positive information, etc.? I’m still using Pololu High Power Motor Driver 24V23 to accomplish this.

jsmith2307

[vicpopo]

Hi jsmith2307,

One question: when did you burn your pololu driver? When you start your sim , when playing under load etc?
Is it always on the same moments or there is no logic behind ?

I burned also h-bridge and for me the problem is identified:
- big worm motor (190 Watt at 12 volts)
- rotor frame impedance or resistor 0,5 ohm !! Yes you red right 0,5 ohm (wiper motors has got 2 or 3 ohms)
When?
- when I start the sim , the first positioning has got a ramp up with no delay.It's like the motor starts on a short circuit.To much amperes are coming...
Solution : until now I didn't find...

Edit : I tried to put a varistor between motor phase and a capacitor.With a capacitor I had not good results (because I don't have the right one I think ).With the varistor that was a little better but it's not the solution , it's just to try to protect the driver (which had its own protection also).

I want to,say also that I had no problem with wiper motors at 12 volts.The problem came with bigger motors.

[jsmith2307]

Greetings vicpopo,
Thank you for your response! It seems like I burn the darn things up on calibration of the motors. After motor calibration, if I get through the motor calibration every thing seems to go fine. If I put the simulator on a break, say if I’ve got to work and can not use it for an extended amount of time it seems like the problem seems to occur on start-up or after I charge the batteries. I’m using wheelchair motors rated at 24 volts. If I run them at 12 volts will I run into any problems increased with amps, heat or anything else? I’m not an electrical engineer just a person that likes to make things go!
I checked with Claire, at Pololu Support and she suggested I increase the supplied capacitors which were 100uf at 63 volts to 2200uf at 50 volts which I did. I was wondering about the length of the leads for Pwm, Dir and Gnd, can they be 4 feet long or longer? Currently I’ve got them at 8 inches but in order to put one motor driver on the front of the simulator I’ve got to run a 4 foot length of the lead to Pwm, Dir and Gnd,. This will cut the length of the OUTA and OUTB (motor leads). Or should I leave things as they are?
jsmith2307

[vicpopo]

Hi Bobbuilt,

Yes , I 've already checked and the isolation is good.I think the problem come from a very low motor impedance , resistor at the start up in combinaison with a not progressive inrush (google translate appel de courant) current .With wiper motors it works because the power of this motor aren't very high ( 50 or 60 Watt I believe).But for bigger powerfull motor the current needed is for far higher.
One solution, because with components(capacitor ,varistor) we didn't find the solution, should be a smoother ramp up,on the first start up for exemple.
And I don't be sure if when playing this problem could be happen when direction changing.

[tonquites]

Hello Thanos,

In our research on the internet, found an H bridge here in Brazil at a good price Super Motor ponte H 43A, which seems to meet all the specifications required for the proper functioning in the AMC 1.6, would like your opinion on this important bridge H.

A doubt in my specific case, is that I have to use 4 of these bridges H. You believe you have a problem?

hug
Everton

Portuguese version

Olá Thanos,

Em nossa pesquisas na internet, achamos uma ponte H aqui no Brasil a um bom preço Super Motor ponte H 43A, que parece atender a todas as especificações requeridas para um bom funcionamento na AMC 1.6, gostaria de sua importante opinião sobre esta ponte H.

Uma duvida no meu caso especifico, é que eu terei que usar 4 destas pontes H. Vc acredita ter algum problema?

Abraço
Everton

[tronicgr]

Hi,

The AMC1.6 supports only two motors so you need two of these h-bridges. I've tested h-bridges with the same mosfet chips before. Look back in the posts I made during summer 2012.

Thanos

[Turn]

Hi Thanos,

Thanks for those detailed DBK reviews. Very helpful.

I have the exact same one. Can you help? I seem to have lost the manual sheet that came with it. Do you remember if it came with one? The schematic on the seller's ebay page is not very helpful to me. Obviously, I'm very new to h-bridges/IC h-bridges.

I've got it powering a light bulb by supplying PWM to IN1_L. If I attach to IN2_L instead, the polarity changes. Makes sense.

But what about for motor control? What are all these other pins purpose?

IN1_L
IN2_L
IN3_R
IN4_R
EN_L
EN_R?

Here's what I think- please tell me if I'm right? I need to generate a complementary PWM pair of signals and apply them to IN1_L and IN2_L. By "complementary" I mean: PWM_1 + PWM_2 = 100% always. Then, as you vary the duty cycle of PWM_1 from 0-100% the motor starts at max speed, starts to slow down as PWM increases, stops at 50%, changes direction slowly, then reaches max reversal speed at 100% PWM? Is that right?

If that's right, then is 50% = a braking condition, or free-wheeling?

EN_L seems simple enough. Is it just like this table indicates?

DBK_mode_3.jpg (26.9 KiB) Viewed 6382 times

And, you said the manual says, (quote from you on Aug30/12): "... that a 470nF ceramic capacitor from VS to GND close to each device is recommended...". Does that mean on the DBK terminal labelled "VCC", i.e power supply? You put a cap on the output side with RC filtering results improving duty cycle noise - did you notice any difference with the cap on the VCC side, or did you not try that yet?

The BTN7960B IC used in it offers a current sensing feature, but I don't see that pinout implemented anywhere on the DBK board. It would be nice use. Is there one?

I'm pretty disgusted with the performance of this h-bridge so far, so want to make sure I'm using it right before I throw it out.

THANKS.

[Mysterious]

hello >>

ANY HELP?


i have to find an alternative Mosfet to the IRF4905, its not available now

ANY HELP ?

[Senetor]

Here is the alternative from STMICROELECTRONICS,

STP80PF55
http://uk.farnell.com/stmicroelectronic ... =STP80PF55
and the logic level N-channel to pair it with,
STP80NF55L-06
http://uk.farnell.com/stmicroelectronic ... 80NF55L-06
both are still available from Farnell element14.


Senetor.

[EmaLau]

Is the AMC source code avaliable?