Here is today's uber-simple bot, an ugly but quite functional duckling. We're probably going to 3D print an improved version of this chassis to use in a robot camp. Two 9g servos, one continuous rotation drives, one steers. And a 1 PPR mechanical encoder. Easy peezy, works every time. Just have to calibrate servo turning radius to match up to a 360 degree turn with an integer multiple of my wheel circumference. In this case, 12 wheel revolutions per circle. Accelerates & decelerates. First test was this figure 8 course. Bot will soon have IR and ultrasonic sensors and audio output. Maybe light tracking too.
Video thumbnail shows bare chassis before the electronics were added. So hideous that it's beautiful.
All my wheels are hacked out of thin sheet styrene, hand-turned on a shaft against a belt sander. Rubber band tire is a slit of road bike innertube stretched around the disk. Crude, quick, works great!
All my wheels are hacked out of thin sheet styrene, hand-turned on a shaft against a belt sander. Rubber band tire is a slit of road bike innertube stretched around the disk. Crude, quick, works great!
No glue on the rubber? I guess if you cut it short enough to stretch, it will hold.
Videos show wheel encoder (Oh Mr. Demille, I'm ready for my closeup) and bare chassis with both servos being driven by a servo tester in oscillate mode. A random pattern, but delightfully fluid.
I love your robot reports! They amuse and amaze me! That's a very impressive figure eight for such an unorthodox configuration. The simple and elegant encoder is great!!
I'm almost inspired to actually do something!! There must be some excuse I can come up with that I haven't used yet.........
Excellent feedback, Rick! Come on in, the water's fine... Here's a table top-sized figure 8 for my presentation today. Didn't even use the encoder, it's quick & easy to use timing commands and calibrate for consistent 90 degree turns. This simple little trike bot is actually a lot of fun to use.
It's fun to watch! I really like how well the outside rear wheel sticks on a turn. It looks like your success with accuracy comes from how well you have center of the front wheel aligned with the center of the pivot attaching it to the body.
If I jump in the water now, I'd have to shove a bunch of other neglected projects off the bench to make room. Of course, I am supposed to have a 3D printer coming and something like this would be post-justification for that purchase! Hmmmm, maybe I can rationalize it that way!!
IMO the best thing is that you can go straight just by steering the servo to a certain location. You don't have to monitor two wheel/motor encoders and synchronize wheels as required by differential steering. Freedom at last!
This older related video is a little hard to watch, as it sounds like fingernails on a chalkboard, but it eventually does do an 8 around 2 IR beacons after some dramatic pauses.
Nice little bot. Tricycle drive definitely has its place in robotics. You lose the ability to turn in place, but can go straight or turn in arcs easily.
New requirement: All contest videos posted this point on must contain either at least one adorable kid, or one cute dog or cat. Extra credit if you can get in at least two of the three!
So Jason, what was the huge package you bought from Amazon?
Pretty sure that was a whiteboard. The box has a huge surface area, but it's only 4" thick. And Whit, this isn't an April Fool's joke - The thing (and the dog) exists, though I'm steering it with a joystick and moving it with balance, so it probably violates some of the rules of the contest.
This is V1, so it's still got a ways to go. It's rideable as is, but I need to change the form factor, and hopefully add wheel encoders so I can improve the control loop and adjust the PIDs for different speeds. Currently I'm using the gyro to keep it going in the intended direction, which works surprisingly well.
There's another video of it in the Projects forum, under "SideWay".
New requirement: All contest videos posted this point on must contain either at least one adorable kid, or one cute dog or cat. Extra credit if you can get in at least two of the three!
I have an image in my head of my baby and the cat in the seat of a cute babyblue hexapod and my wife screaming at me. Would the angry screaming detract points?
I hear that argument often, but of course it depends on how you view your chassis. Many diff steered chasses are circular, so it's easier to visualize. But if I put a circular body on a trike chassis (and keep the CG forward of the two trailing wheels), the two behave very similarly. The trike's powered wheel becomes the caster on the DS robot.
@erco - agreed and a very different movement from the old ARobot with exactly the opposite arrangement - that is - one drive wheel and two wheels that steer - all located at the perimeter.
Comments
[video=youtube_share;0PgDEv8_bMk]
Video thumbnail shows bare chassis before the electronics were added. So hideous that it's beautiful.
Nicely done. Love the rear wheels and tires.
No glue on the rubber? I guess if you cut it short enough to stretch, it will hold.
Looks nice man.
I love your robot reports! They amuse and amaze me! That's a very impressive figure eight for such an unorthodox configuration. The simple and elegant encoder is great!!
I'm almost inspired to actually do something!!
If I jump in the water now, I'd have to shove a bunch of other neglected projects off the bench to make room. Of course, I am supposed to have a 3D printer coming and something like this would be post-justification for that purchase! Hmmmm, maybe I can rationalize it that way!!
Same bot does "slalom" course faster: https://www.youtube.com/watch?v=9152JjyRkJE
Oh yes, it does! Well done Jason.
!0 Points!
Jim
It's not an April Fool's CGI creation is it? The dog looked a little fake... :-)
So Jason, what was the huge package you bought from Amazon?
That looks really cool Jason, is it almost ready for production?
-Tommy
I am with Tommy!
Great project - who, or whatever is driving it!
There's another video of it in the Projects forum, under "SideWay".
I have an image in my head of my baby and the cat in the seat of a cute babyblue hexapod and my wife screaming at me. Would the angry screaming detract points?
Well done, as always!!
I hear that argument often, but of course it depends on how you view your chassis. Many diff steered chasses are circular, so it's easier to visualize. But if I put a circular body on a trike chassis (and keep the CG forward of the two trailing wheels), the two behave very similarly. The trike's powered wheel becomes the caster on the DS robot.