How to control a motor
Dan Michaels email (remove spam text)
Tom Handley wrote:
> Dan, I took a look at that Nikko Hummer and I've had similar problems. My
>car has a mechanical lever to switch between high and low grear ratios but
>even then, the ratio doesn't supply much torque at the low end. This car
>uses an H-Bridge but no PWM in the original. Their "Turbo Boost" is simply
>bumping the motor voltage from 6V to 12V. The front steering is a motor that
>drives the wheels to one side or the other with a limit switches made out of
>a cheap PCB with wiper arms. Anyway, I quickly decided to throw that out and
>start from scratch...
I was off looking at the RadioShack cars this weekend. I noticed
some of the 4WD trucks have a high-low switch on the differential
- indicating gear-switching. Not sure how many feet/sec the cars
go in low-gear. Of course, no one at RS can ever answer any
"technical" questions, but the high-gear on these cars is 500ft/min,
much below the 1200+ for the racers, so low-gear may be usable.
However, you seem pretty low on the RC-car route.
Also, I noticed RS and others have an M1 tank, with cat-treads
and a motor for each side - just the sort of thing you were after.
Have you checked this out? Probably pretty slow and torque-y.
Most of these 4WD jobs with low-gear say they can climb 37-45deg
slopes. sounds like plenty of torque. I wonder if the new year's
offerrings have addressed the slow-speed/high-torque issue better
than in the past.
> Again, the problem is torque and the gear ratio. I'm using the 16F876's
>PWM but I have to ramp up the PWM duty cycle quite a bit to get it to roll
>and then back down to track my target tach speed. Right now it takes about
As mentioned, maybe the new year's 4WD trucks or the M1 tank do
better in the torque arena.
> I'll have to admit I'm addicted and, due to the modular nature of my
>`hacks', I can easily use them on another platform. I would love to get into
>"Battle Bots" but it takes lot's of money and time and I really don't
>consider those robots, just R/C toys on steroids ;-)
I figure about the "best" battle bot would be a thing with a
circular scythe that would stick out and flip over the enemy from
the side. [Leonardo invented this 500 years ago for hacking
enemy troops in two - but all you had to do was shoot the horse
that pulled it].
I think it would be fun to build an autonomous bot that would
wander around on its own and map the terrain. Come back home
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads
See also: www.piclist.com/techref/io/motors.htm?key=motor
You must be a member of the
piclist mailing list
(not only a www.piclist.com member) to post to the