Stepper Motor Torque issues

M

malcol

New Member
Hello all - a long shot with 24 hours to go before project presentation in Birmingham!

We have built a helper robot based on a Roomba vacuum cleaner, using Astrosyn B355 Steppers to drive a lazy tongs style lift on top. Have tried the test program from the manual (p17) with the correction in line 10 and have motion....

However, there seems to be little torque driving our threaded rod (in fact you can stop it with your fingers....)

Any thoughts/ sample listings on increasing torque would be much appreciated!
 
M

Mycroft2152

Senior Member
Acording to the data sheet, you will get the most torque at a step frequency of 100-200. That will also suckup about 500 ma. A 9v PP3 will not provide enough milliamps.

What is your step frequency and current draw?
 
M

malcol

New Member
Mycroft2152 said:
Acording to the data sheet, you will get the most torque at a step frequency of 100-200. That will also suckup about 500 ma. A 9v PP3 will not provide enough milliamps.

What is your step frequency and current draw?
Click to expand...
Getting beyond my knowledge limit now! Just following the circuit diagram and listing in the manual. Have checked connection and it is firm - can stop motor with fingers! Have resorted to bench supply - new motor rated at '5V nominal...' have wound up to 10V on the bench seemingly with no ill-effects but little improvement.

I am convinced that there must be a way to improve the torque with the software - in the Lincoln PICAXE Book it says to use this:
--++
-++-
++--
+--+
but when I tried (using 0 and 1) in the original listing the motor just buzzes.....getting desperate now..!
 
E

eclectic

Moderator
Last faint hope.

At the end of the program, insert

pause 5, like this

let pins = b2 ‘ output b2 onto control lines
pause 5
return

Does it make a difference?

e.
 
M

Mycroft2152

Senior Member
M.

On any project, the FIRST thing to do is to run a Search on the forum. Most likely you question , or something similar, has already been discussed.

Steppers are a popular subject.

Run a Search on Astrosyn.

One thing you haven't mentioned is what your steppers are connected to. Are you using driver transistors? all the power in the vorld will not be effective, if it is not getting to the coils of the stepper.

There is a limit on what you can do in software, it is the hardware that has more potential for tweaking. Understand that, The stepper you are using is a very small low power stepper. You can't put a Volkswagon car engine in a jet plane, and expect it to gwet off the ground.
Myc
 
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