Continuous Motor coding...

Jed

I'm looking at the manual for the continuous motor and it shows a pulse duration of 750 for center, 600 one direction and 900 the other? This is different than the 500,750,1000 duration I've been using with the unmodified servo. Why are the limits lower? I was expecting the numbers to change the speed of the rotation, with 500 being the fastest in one direction and 1000 the fastest in the other, 750 being no movement at all. Can someone please clarify how the pulse codes effect the modified servos?

Mike Green

There's some variation from servo to servo and from manufacturer to manufacturer. The only number that's fairly consistent is the 750 which represents a 1.5ms pulse (with each unit being 2us on a BS2). Most servos respond to a range of 1ms to 2ms which comes out to a PULSOUT value range of 500 to 1000. The continuous motion servos tend to plateau as you get close to the ends of their pulse range, so they respond less to variations near the extremes, so there's little difference between 500 and 600 or between 900 and 1000.

Jed

What about controlling speed. Can I do that with the duration (farther from center being faster) or do I have to do that with pauses?

Mike Green

Very close to the center value (750), the motors will slow down and that can give you some speed control. You'll have to experiment with values. Maybe you can plot speed (RPM) vs. PULSOUT values. Do keep in mind that these motors were not designed for fine control of speed.

Jed

Ok, I'll try that when my servo gets here. What about adding resistors to the servo's power supply? Will that slow the motor down any?

Matthew Burmeister

i would think it would. since servos are motors and i have read that you can add a resistor to a motor to slow down the motor

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
print "connecter"
input "Which com"; com$ ' displays text and lets user chose which com
open com; com$ for read ' opens com
close #com ' closes com
print "Com closed" ' displays text
end ' ends or stops the program
' JBASIC code www.justbasic.com

bennettdan

Jed
Read the WAM text their is a section on how to control the velocity of a standard servo this should be what you are looking for. Look at activity #3 converting position to motion on page # 125 in this text.
www.parallax.com/Portals/0/Downloads/docs/books/edu/wamv2_2.pdf

Jed

Thanks bennettdan, but I believe that code is for an unmodified servo. I'll be using a continuous servo and was hoping the duration would control the speed better than it's sounds like it actually does. I'll figure something out.