Stepper Improved ramp.

BTX

Hi all.
Here's my 2nd version of PaP controller, it's an improved acceleration/deceleration ramp and a better control for pulses sent, it accepts any quantity of pulses, and adjust automatically the ramp for each.
The ramp could be controlled by a potenciometer using RCTime object, as the speed too.
This adds too, a zero machine state, to get an initial position of motors from start (with 2 sensors per motor), you can call, it zero position, any times you want, by sending a null byte to a variable.
Since it is for replace some existing hardware on my machines, some functionality is a quiet·strange, due·to maintain compatibility with my old system.

Hope it could be usefull for somebody.
Regards.

Alberto.

PS. Could be good some feedback.

Envio editado por (BTX) : 12/12/2006 1:39:29 AM GMT

babinda01

Hi Alberto,

Looks very interesting, thanks for sharing it with us.
What type of machine are you controlling with this controller????
I am planning to have a bash at making a simple CNC controller (seems a few other folk are as well). I would love to have all the motion profiles (linear, circular etc)·done onboard the prop chip and just send serial commands from the pc.· I would love also to·implement an encoder feedback system for·closed loop stepper control.
Not sure I have enough time to make it all happen, but it will be fun trying.
Thanks again for sharing your system. It will give me a starting point to play with.

Best Regards
Andrew.

Gavin

Ditto linear, circular curves.

I stated a yahoo group for a microCNC controller recently.
http://groups.yahoo.com/group/MicroCNC/
It has ended up being a propeller based design because it kicks Smile compared to other alternative micros.
There are some schematic files on the yahoo group and I have started some test pcb layouts.
I would be interested in any suggestions.

I have seen a few threads now on stepper controlling, perhaps we can start a sticky thread on motion control?
It can be hard to find the old threads. Seperate sticky for BLDC motor controllers?

Gavin

BTX

Thanks Gavin and Andrew.

I'm automatizing brooms and brushes machines with this motors,one per axis x,y,z.

These are big machines I'm using 6.5 Nm Sig Positec motors, those motors are obsolete parts for new machines, but in my country, the servos has a·veri big price, and that is·too much for the budgets for·my clients. (take a look at www.btxsistemas.com.ar "Fotos" = Pictures in Spanish)

Look at this thread..there are some video about positioning: http://forums.parallax.com/showthread.php?p=619570

Talking about CNC machines, this code is not usefull, cause it's good for many positions one not near the following,·but it's very easy with propeller to implement a·Bresenham algorithm to do CNC, and using the same technique, could be great.....send the Gcode by USB and then let the propeller to do the job, I would like to do this..but I've not never time...my CNC project is ever waiting......

Gavin. I'll see the Yahoo group early....

Thanks guys and regards.

Alberto.

Gavin

Alberto, lucky there was pictures my spanish is non existant.
That is some serious size motors. Are you using encoders for feedback?
Going to stick bable fish on you.

Animitronics? 32 I/O, 32 servos?

Gavin

BTX

Gavin.
I'm not using encoders for feedback, is is not necessary, if motor torque is correctly chose, and if your controller works fine, you'll never lost the correct position.
In fact, these machines position turning about one turn each motor "x,y,z" 230 times in a minute, working 12 hours per day and never lose steps.
Sorry... my English is worse than your Spanish..."Going to stick bable fish on you." What means that ???????

Not so many servos........
Look at this: http://www.btxsistemas.com.ar/Fotos%20y%20Videos.htm
The three last are videos.

Regards.
Alberto.

Gavin

I thought they were servo motors, steppers won't need encoders.
Some people say servos are better because they never lose step, you just proved that good steppers work well.

Altavista babelfish spanish to english translation.
http://babelfish.altavista.com/

Sometimes chinese and Japnese translations are very funny.

Gavin

BTX

Gavin.
Our test results, give, servos are fastest than steppers, more resolution, and have a big torque on the start, but here they're too expensive.
For low speed applications and no so high resolutions, stepper were fine, and cheaper !! We use them between 4 Nm to 14 Nm.

I'll try with that translator....hahaha... mine give very very funny answers.
Regards.
Alberto.

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Gavin

Cheap servos are second hand ones[noparse]:)[/noparse]
Got mine when someone was throwing out old computer tape drives, cost zero and a bit of missing skin.
Still need to belt reduction drive for them, way too fast, steppers are just easier to use.

Yippee counter ap note is out, need that for better understanding the counters relating to motion controll..

Gavin