One-Motor Line Follower?
Is it possible? I have a design I'll build & try soon, so I'm throwing it out here to see if anyone else has any thoughts. Slow and simple is fine. Could be micro controlled or just analog hardware, but just one motor (or one servo if you want to take a shortcut). Any kind of sensor, but simple and cheap are always mo' bettuh.
The world is rife with two motor line followers (or one servo, one motor).
http://www.ebay.com/itm/272315964424
http://www.ebay.com/itm/221236229751
I hope to copy that last design where the motor shaft is the wheel/roller, tilted and in direct contact with the ground. No gears. Cheap!
The world is rife with two motor line followers (or one servo, one motor).
http://www.ebay.com/itm/272315964424
http://www.ebay.com/itm/221236229751
I hope to copy that last design where the motor shaft is the wheel/roller, tilted and in direct contact with the ground. No gears. Cheap!
Comments
1) The single motor drives both wheels via some arrangement of gears and or belts.
2) There is a ratchet mechanism in each of the left and right drive chains such that:
a) When the motor is driven in one direction it drives the right wheel forward but the ratchet in the left drive chain slips.
b) When the motor is driven in opposite direction it drives the left wheel forward but the ratchet in the right drive chain slips.
With this we can drive to the left or the right.
By alternating the direction of the motor we can 'wiggle' along. A bit to the left, then a bit to the right, bit to the left again...But on average in a straight line.
By varying the mark-space ratio of our left and right drive we vary the amount of turn left or right. Hence steer the thing.
All in all it's like rowing a boat with only one paddle.
Can't help thinking there must be more elegant solutions though...
A two wheel bot with a rear castor wheel.
Give it two "legs" sticking backwards. One left side, one right.
A servo driven in one direction pushes the right leg backwards, which pushes the bot forwards and a bit left.
Driven in the other direction pushes the left leg backwards, which pushes the bot forwards and a bit right.
Legs retract by springs.
If the servo only moves from center to right the bot is pushed left.
If it only moves from center to left the bot is pushed right,
Full swing on the servo gets us wiggling in a straight line.
When a motor drives in one direction the body of the motor is being pushed in the opposite direction.
Normally motors are rigidly mounted so their bodies don't move w.r.t. the chassis.
But what if we don't rigidly mounted. Then as it drives the torque reaction could rotate the body a bit.
That movement could be used to engage or disengage the left and right drives. Perhaps by altering the tension on belt drives and allowing them to slip or not.
Martin: You're a busy guy, so just combine challenges.
Peg puzzle, one motor. Done.
This clutch has three concentric disks. The outside two drive left and right wheels respectively.
The center clutch disk can move along the central axis a bit, thus engaging with either the left drive disk or the right drive disk.
By use of some helical shaft of for that disk the direction of drive will force it along the axis to engage left or right drive disks.
This sounds much more compact and elegant. If you can make it...
Edit: The bot is fully mobile and driving fine. It's not following a line yet but that's an easy peezy addition. Will also locate and track light and/or IR beacons.
At the risk of being called a spoiler or party pooper it seems to me that all of the suggestions for using one motor are more complicated than adding a second motor. They need two ratchets, clutches, swashplates, legs, linkages, cams, sliders, hooziewatches, doodly-boops, or a compressor and motor as well as two valves along with the control circuitry.
Can't wait to see it.
Two wheels, one left side one right side. Free wheeling. But ratcheted so they can only roll forwards.
The motor drives a tail wheel. But the tail wheel is transverse. It drives left to right not forwards.
The result of this is that if you drive the tail left the bot pivots around it's right side wheel. Drive the tail right and it pivots around the left side wheel. Overall forward motion and steering.
@kwinn,
Yes you are a spoiler. Two motors may well be easier. That is to say boring. The restriction of one motor makes it an interesting challenge.
At least not after I checked your second link in the opening post.
Actually years ago I bought a little robot kit for my 12 year son. It did not have wheels, just motors, mounted at funny angles, whose shafts rested on the floor. Bits of rubber tube pushed over the ends to get some grip.
How do you get out of blind alleys, or corners?
(just teasing)
Dave
I would love to see an example of a Heater-Built robot, The GP will probably have to study it for years. And may change what we take for granted in the art of robotics.
1) Gentlemen plan/scan ahead and turn accordingly.
2) Getting stuck in a corner is bad form.
I have not built anything resembling a robot since messing with meccano as a kid. They don't really count, they had motors but no brains. Sadly I did not have the where with all at that age to combine the sensors, transistors and stuff of my early electronics experiments, with Philips Electronic Engineer kits, with the mechanics of meccano.
I have been day dreaming of building some kind of smart bot, even with an analog brain, since high school circa 1970 something.
The result of all this. Nothing. Not one bot. Except that little Chinese kit my son and I assembled over ten years ago. And I have another little bit more sophisticated Chinese kit half built here and waiting for a Propeller brain transplant for a couple of years now. Is this a challenge?
Quite likely it would be different. I doubt it would change anything though.
No, I'm sure you have more important things to do, and your expertise should not be confined to a small platform. But a life-sized human like robot. If we could copy your knowledge and experience into a robot brain with an Atlas body, No telling where we could go, movie deals and supreme ruler to name a couple. Seriously Parallax Forums would have you around in 2116 for are much needed evaluation and consultation.
If you have the time, maybe a differential drive bot with a Propeller brain, something we could call Heater Jr.
Now, about that "supreme ruler" thing. That tickles my fancy...
Why try to grow organs, replace hands/arms/legs, etc?
Why not work out how to detach the head, supply the head/brain/eyes with blood/nutrients from a machine, and attach a robots sans head, controlled by your brain
Might extend your life by decades.
Research would be minimalised to what nutrients to supply the head with to keep it all working nicely!
https://www.walmart.com/ip/Meccano-MicroNoid-Basher-Blue/51503491
@Ttailspin: Ratchets and casters are for suckers.
Curiouser and curiouser!
Or badges!
Carefull and don't loose your magnetic undergarments.