Ridiculously Huge RC Kart - $3,000 beast

[smooth90]

This is an awesome build!!!

Just one question though....I see that the frame is just tack welded together. Are you not concerned about that?

The large metal sheet is all one piece then the frame is welded on top of it. The metal sheet is tack welded to the frame. I will likely run a few short weld beads around the frame soon. Gravity is basically compressing the bottom and the top together so the tacks just keep them together they aren't taking a lot of stress (in most places) especially when compared to the corner welds on the square tube frame. Around where things are actually mounted to the bottom plate I'll definitely need to add more welds. I decided to tack weld only so that I could get everything assembled without warping, now when I go to finish the welds the risk will be a lot less since there's a lot to pull everything its the shape I want. I'm not an expert welder but in the beginning, I learned just how much overheating and warping can wreck a project lol

The turning radius on this doesn't look too sharp but once I got the tie rods on it's actually not too bad. I would say the wheels can turn about 35 degrees tops. I tried to get it higher but with the size of these wheels of how small I was trying to make the frame, there was a tradeoff between the two imo.

Here are some new pictures, I finally got the tierods in. I'll be hooking up the stepper motor electronics soon and testing it out. The big electronics enclosure comes in a couple days and then I can start loading it up with stuff.

 

[ezcome-ezgo]

Where did you source the steering box?

 

[Kartorbust]

Looks like a normal mini buggy rack and pinion, could be wrong, with an electric motor or servo at the end of it.

 

[smooth90]

Where did you source the steering box?

Sorry for the late reply,

I got it off ebay, it is a really nice little rack and pinion setup. The steering motor is a Nema 34 stepper motor. The part connecting them is a 3/4" to 3/4" shaft coupler with a rubber part in the center so it can flex and not be perfectly aligned. Another thing to note, the rack and pinion has a 5/8" x 36 spline input shaft so I bought an adapter off amazon that converts it from 5/8" x 36 spline to a straight 3/4" shaft. Then I just used a piece of 3/4" cold rolled steel to connect the adapter and the shaft coupler. Just an FYI if you buy that rack and pinion and 5/8" x 36 spline to 3/4" shaft adapter, you have to really hammer it on or at least I did. It will never come off. It should have slid on but I don't know why it didn't fit correctly.

Heres the rack and pinion link:

https://www.ebay.com/itm/8-1-2-Thin-Line-Billet-Rack-Pinion-for-Single-Seat-Buggy-Mini-Rail-Go-Kart/190737043387?hash=item2c68d04fbb:g:w~gAAOSw8x1ZepFW&vxp=mtr

This is the stepper motor that I'm using:

https://www.ebay.com/itm/NEMA-43-Stepping-Stepper-Motor-1586-oz-in-3-4-single-shaft/380937499458?hash=item58b1a4f342:g:v5YAAOSwq5lTrDjr

---------- Post added at 01:37 AM ---------- Previous post was at 01:28 AM ----------

So I've been working on this a lot since I last posted. I have been getting the project enclosures all set up. In the pictures you'll see what I'm talking about, it's not like a standard RC car, there's a lot going on inside that box.

Also, check out the emergency/control enclosure (its the one with the big red button on it). I haven't programmed it yet but once I'm done with it everything on it will be functional. All of the buttons and switches will serve a purpose. It'll serve as an emergency cutoff device to kill the rc car should it go haywire but it'll also let me monitor things. I'd like to be able to monitor engine temperature, rpm, speed, etc... These are all pretty simple to do.

I'm extremely close to being done. Tomorrow I'm going to be testing out the remote control to see if the steering/throttle/brake really work (software plus hardware). It it all checks out I could be driving it tomorrow night or within a few days!!!

 

[itsid]

wow..
as much as I love ratsnests like these (the puzzle nerd in me loves them... the german in me hates them LOL)
Anyways, five nanos??

What will it be able to do in the end?..
One should be able to do everything you want...

I understand that it could make some sense to source out unimportant controls (say lights accessories etc) and run important stuff (steering brakes) in redundancy.
but that'd make it three; even if I add one master to do nothing but check states and flip between the redundant control when necessary (not exactly what I'd do but okay)
I can't get past four...
Five? I'm lost in trying to imagine what you do with them ATM.

I count 20 relays... that's more than a handfull of toggles...
I'm curious.
one nano for the 16 array??

'sid

 

[smooth90]

wow..
as much as I love ratsnests like these (the puzzle nerd in me loves them... the german in me hates them LOL)
Anyways, five nanos??

What will it be able to do in the end?..
One should be able to do everything you want...

I understand that it could make some sense to source out unimportant controls (say lights accessories etc) and run important stuff (steering brakes) in redundancy.
but that'd make it three; even if I add one master to do nothing but check states and flip between the redundant control when necessary (not exactly what I'd do but okay)
I can't get past four...
Five? I'm lost in trying to imagine what you do with them ATM.

I count 20 relays... that's more than a handfull of toggles...
I'm curious.
one nano for the 16 array??

'sid

The four solid state relays form an H-Bridge to drive the brake motor, I tried using several types of brushed motor controllers but for whatever reason nothing but this diy H-Bridge worked which was a major pain. The 16 channel relay board isn't really being used (well one relay is) but in the future, it will be. I put it in there so I could upgrade the whole system with headlights and other accessories.

As for the five nano's, three of them perform the core functions (steering, throttle, brake). I chose to separate them like this because it's really compact, makes the code super simple, and made the wiring simpler. If I had used a Mega to do this the wiring would've been even more complex and the code would've had to make sure that all of the tasks were tended to in an orderly fashion. Arduino doesn't support multithreading so utilizing 5 arduino nano's is kind of like having 5 separate concurrent threads.

The fourth nano is the emergency override system, it can cut the engine, engage the brake, and report back data in the future.

The fifth nano currently doesn't have a purpose but I figured I'd put it in ahead of time because I'll probably find a purpose for in the future.

 

[itsid]

Ah I see..
concurrent threads.. I see..
Not sure if that's indeed necessary here but it's surely a viable solution (especially considering the costs of an Arduino nano LOL)

Anyways.. I myself would've likely have a single control loop
with an if-brake on top and a combined while for throttle and steering
that way you can sync throttle and steering update
and the brake would be checked (and override) once per PWM step.
IMHO that'd be enough multithreading for this case..
[ I MIGHT BE WRONG THOUGH! ]

but one more question about your setup..
You have a brake override throttle check? since the last thing you'd want is to power the motor while applying the brake.
and with seperate Arduinos that could be a pain to set up (either you check two states on the throttle arduino, or you need a serial connection between the brake and throttle nanos to transmit the "turn off motor" signal that overrides the throttle...

'sid