closen-loop servo control?

I newbie and need big servo driver whit my cnc project,
how i can make servo driver and feedback in to encoder.
I thing i drive fet irz44 type high voltage and current(servos need 80V 20A)
put dont know what i start,computer come out step/dir signal(master5,mach1,mach2 softwares)
have here some what work same project too?
i need scheatic what drive servos(3-4 axle)and how i connect picaxe thats,and pc-picaxe connection to parallerport? or serialport realtime.
secon proplem i need temperature driver to ac fan control.i understand input i made NTC to analog input measure temperature ok.but what i need output? how i control fan speed linear? or i thing possiple etc,08M serial pic do drive 4 step different speed to fan,
have some schematic what can control linear 230V ac motor,and include pixace instal here drive speed?

your question is too complicated to answer in a forum like this, ( someone will prove me wrong), you would be better off looking at the Picaxe manuals for driving stepper motors and doing some further internet research. Then when you have some ,more exact questions we may be able to help.

try the following links:

<A href='http://www.cs.uiowa.edu/~jones/step/' Target=_Blank>External Web Link</a>
<A href='http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/connect.html' Target=_Blank>External Web Link</a>
<A href='http://users.pandora.be/educypedia/electronics/motorstepdriver.htm' Target=_Blank>External Web Link</a>

also search for CAM software there is a lot of information out there.

I think stepper driver are different what dc brush servo motor driver? right?
I have working stepper motor system cnc-machine and working good use master5,mach2.
but find schematic anf how I make brush dc servomotor driver whit picaxe.
because servos all run high voltage 60-130V stepper 5-24V highes have do but i use 24V steppers,and servos use nominal high amperes 10-20A nominal,and sepper board meny use max 2-2,5A,stepper boar NOT can use servomotors when current is highes.
find schematik what same type is rutex.com are,rutex servo driver use 20-120V 20A
and input are normal driver signal step/dir out to computer,nominal paraller port out,meny new driver too serial port.
old stepper all drive step/dir signal paraller port.
no proplem what port driver use,mach2 cnc-control can use all.but need board what can use high current 20A and high volts 60-130Vbut dont found where.now I think must make own driver picaxe and need information what code inside,and board ,
sorry my englis not good but hope you understand what I thing.I have good working cnc but need better,change driver and motor to betters,servos have high torgue stepper have not high torgue only nema 42 serie but smal .small servos have highes torgue than biggest stepper,you know.
how I can make high current/volts board to servomotors ?
these picaxe is my first microcontroller and i newbie thats,stepper board i make itself style l297-298 (max,2,2A) and working good but servo not can drive same board.
and servos have more proplem-encoder feedbac and thats signal must read too.stepper boards not handle encoder signal.you know servo/stepper have very different driver.

Hello, You need to beak the problem down into small parts and do each one separately.
You may find that the picaxe may not do what you want it to. I gather you've seen, or used the l298 driver chip and seen that it has a limited current draw.

I would think that you need to use FETS to be able to handle the high voltages and currents, you need to take care in the way you design the circuit as the currents and voltages you are talking would fry a picaxe chip no worries.

We still need more information, as to the exact problem you are trying to solve. I still don't quite understand what your trying to achieve

 

It is possible to use a PICAXE as the basis of a servomotor. You can quite simply write a program to implement a closed loop feedback system. You will need to use the PICAXE monitor your demand and positional error signals and send out appropriate motor drive signals. If you do this, will have to buffer and then amplify the PIC outputs in order to drive a motor. The real issue is how you implement your demand signal. If you are using standard radio control signals then you can use the pulsin command or alternatively you can read your demand as an analogue signal. I recommend a PICAXE with a 12-bit ADC rather than the standard 18-part number.

just a thought if you are planning on implementing a tachogenerator servo system you could always use something like this: http://www.interq.or.jp/japan/se-inoue/e_pic6_91.htm

The usual approach when building any CNC equipment is to buy the drives matched to the motors. That said, very few servo motors can't accept mains voltage so the drives are the limiting factor for what voltage can be used.

Designing your own drive is not for the faint hearted and is a very expensive exercise - not recommended unless you intend to make hundreds of the suckers.


You get many options on prefered control method:

- The drive can be designed as a dumb amplifier which simply operates in torque mode, although, it will have an internal servo of sorts based on internal current sensing. The amplifier is commanded by an analogue signal of +-10 volts. The feedback device does not connect to the drive but instead goes straight to the controller (There is a kind of exception to this, old 3-phase brushless drives need the three hall sensors for field switching orientation but this is in no way the velocity or position feedback). The controller must perform all the servo functions. This can be a very rewarding setup because the controller will have many MIPS to spare and can perform complex synchronised tasks like multi-axis milling.

- The drive can be designed as a speed controller that performs a layer of servo control based on the motor speed which comes from a feedback device attached to the motor. The drive is commanded by an analogue signal of +-10 volts. The controller can be a simple one for simple jobs but still needs lots of MIPS for synchronous jobs.

- The drive can be designed as a position controller. Usually, this means a fully digital unit and will have both of the other modes selectable. The feedback device has to provide position data and if it is not an encoder then the drive will also have the feature of producing simulated encoder signals for an external controller to monitor. In this situation the drives can often be linked together and programmed to work in unison with movement commands arriving via a datalink and therefore not really needing a controller as such. The &quot;controller&quot; becomes the &quot;frontend&quot; data store, massager and operator interface.

A second common variant of the position controlling drive is it can follow another encoder or stepper pulse stream. Feedback is only between the drive and it's motor and is not usually used by the controller as the drive should be able to keep up with the pulse stream from the controller. It sounds like masaV is using this sort of setup already with the existing steppers so it makes a lot of sense to extend this approach.