T4-K9 Cog the Dog Build of T3-01 Dancing Rider
I first drew Cog the Dog about 10 years ago and have been trying to build him ever since. I only got serious when I finally saw the Tamiya T3-01 Dancing Rider in October 2018. I immediately bought two and got to work figuring him out.
Early versions of Cog used LEGO Technic parts for easy prototyping as I experimented with steering geometry. Tamiya's T3 brilliantly uses a caster-type free steering at the front that is basically gravity controlled. A dozen Lego/Tamiya hybrid versions left me wanting something more stable...less likely to fall apart as I drove down the street. Cog 1 has a differential at the center of the front arms, and automatically adjusts the arms to suit the hip servo's lean. A simplified version of C4 could easily use this technique and still get adjustable rake on the front forks by adjusting the outer ring, but I digress.
With Cog 1 in a nice stable state I took the remaining parts and started to build Cog 2. Cog 2 originally used the cheapest servos I could find and was a little slow and sloppy. One slipped gear convinced me to get APEX fast servos and despite having arms hooked directly to servos, I have over 8 miles on Cog with no servo failures.
Initial tests were great, but winter took hold and I put him on the shelf. I was having a difficult time controlling the arms (set on the controller to a Delta Wing) along WITH the hip servo. I knew I needed a new radio, but it would have to wait.
Spring of 2019 I finally got my hands on a 10-channel FlySky controller that would do the trick (FS-i6s) and after a significant amount of trial and error I got the chassis and all three servos working together. But Cog2's paper head, while fashioned from the T3 box, just would not do. Close examination of the lower half of the T3 battery cover and a little imagination...and I could see a dog. Maybe more of a Voltron Lion, but it could work. I grabbed scissors and hacked away at the body shell some too. Yes, that could be eyes and ears and a helmet with an open back. Wrapping the lexan around and gluing it into a strap confirmed it. Slightly out of scale and kinda bobbly, but it was right out of the kit...T4-K9 was born. Looking at extra pieces from the C1 build, I also had the entire radio deck and rear tail and 'spoiler' as extra parts. Flipping them around a little doubled up the C3's top space frame into a usable shoulder/neck structure, and I had a platform.
Finally I added Adafruit's little micro-servo based pan and tilt on the platform and got to mounting electronics. The FreeSky 6-channel receiver is embedded in the nose, light controller is floating at the back of the head, loose.
The bottom battery cover pan was getting in the way of Cog's aggressive all-forward high-speed runs, so it was removed. The battery (a Venom 7.4V 1300 30C) sticks out a little, but made a great belly pan for sponsor logos.
In my first full-speed run I realized I had not glued the front tires. One rolled out and jammed, and Cog did a fantastic single-point handstand 180 and came down facing me with the engine still at full. The transmission didn't do well, the plastic/metal differential shattered. I was very proud.
Upgraded aluminum ball differential and steel axles brought C4 to final form.
High speed tests with an iPhone6 strapped to his back have Cog clocked at 24.2 mph. By the end of summer we will crack 25. (on 6/2/19 Cog hit 25.4 mph at the high school track)
I would love to see Tamiya take try at the C3-01 Chassis as a robotics kit. The chassis is really easy to work with, the caster front legs would even cater to a two-motor back-end. A sufficiently powerful version could self-balance.
I will next be experimenting with a few steering geometry ideas in Lego, but hope to start a Micro Servo version of C4 later this year. I also am planning Arduino integration later this year in hopes of eventually having a Cog that follows me on walks around the block, or can autonomously race other Cog's at the local dirt track.
SLOW-MO: https://www.youtube.com/watch?v=lnL_Zm5uwGQ
Movie Trailer: https://www.youtube.com/watch?v=c5BkB9NFOUE
5-MINUTE EPIC MOVES: https://www.youtube.com/watch?v=Gbt0KDOL7qY&
Comments
MAD-BEE
Brilliant!!!!
neobrunox
Very creative !! i like
Tamiyastef
It deserves it's own movie! This is great.
neobrunox
i see the vid, Tamiya can be inspired by you
pininy
Looks like fun!
Mr duke
Amazing love your work
BWGunner
Thanks all you have been so kind! Here's a big LONG video about Cog I made over the weekend. If you too want a T4-K9 make sure to Like and Share and post it to everywhere with #tamiya and #tamiyausa tags anywhere you can!
[Click here]
bjorklo
Congrats on such a genius rc ride. well done. I for sure would love to have one like that, and I'm pretty sure many others to would.
Tamiyastef
The video is really really nice! It's something else to see it on the move. I got visions of 6 T4-K9's chasing a T4 rabbit on an oval or a dozen T4-K9's chasing one T4-Feline. A whole new range of races is born!
BWGunner
@TAMIYASTEF That's a pretty clear vision. Yes!
My original daydream of Cog is centered around community Dog Races at local parks. Set distances with 'stock' Tamiya T4-K9s building to a side event at National races where stock dogs race a less technical, more organic event. Of course we'd have to have custom and modified divisions.
I can see a whole industry in just providing different head modifications. Different breeds, of course, but also different sensor and brain combos. Eventually I'd love to see Arduino powered rigs doing technical events with jumps and ramps and self-navigating of the course...with a trainer shouting at it, of course!
I adore the idea of a T4 Cat. You have inspired me!
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