Cerberus - Robot Protector of The Realm!

Radical Brad

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Something I started back in my city days. Dug this out of my collapsed junk shack and put a little work on the rear steering system. This large robot will autonomously patrol our farm and chase away deer and bears. I will be using a combination of GPS and machine vision, which is much easier these days thanks to advances in deep learning and embedded computing.

Other features onboard will be...

  • Ability to take manual remote control (5 mile range).
  • Live video and audio feed to base station (house).
  • 3 joint robotic arm with a 10 foot reach and gripper.
  • Follow me mode and facial recognition.
  • Bear spray system for any problem intruders.
  • Possible garden watering.
Here is the frame so far. The Jeep differential has been narrowed by over 16 inches (by me using only hand tools).
All three wheels steer so the bot will have an amazingly small turning circle. Front wheel drive.


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The frame tubing is 5/8 wall 2x4 inch rectangular tube.
I intend to have a lot of fun with the body, maybe doing fiberglass work again.
Here is the "master plan", pretty much all I have for this entire build...

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Brad
 
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I did see some little robots that were ' autonomous ' and when the batteries were low they went to a charge station and plugged themselves in ?
 

Radical Brad

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Yes, I forgot to mention self docking. This will have that as well, and since Cerberus is a 3 headed dog, I guess it will be a dog house! The bot will mostly hide in its charging house, waiting for a deer, bear, or human to come on the property. At that point it will respond accordingly.

Brad

I did see some little robots that were ' autonomous ' and when the batteries were low they went to a charge station and plugged themselves in ?
 

Radical Brad

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The arm will have 4 degrees of freedom, and the turret will be able to spin almost 360 degrees. So... yes absolutely, there will be target tracking. I will most likely only allow weapons to fire under manual control though. I have had some painful lessons with my previous bots (and scars).

Brad

I don't see rotating auto-cannons in the design. I'm sure it will need them.
 

Radical Brad

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Finished the main frame on my lunch break! Now I just need to find another steel 17 inch rim, some bearings, and then complete the triple tree fork. After that, the fun stuff can happen... adding the main drive motor and 3 wheel steering servo.

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The old AC stick welder still works! Has been buried under snow and then wet grass for some time.

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Slight negative caster angle on the rear fork, and no rake. This robot should have an amazingly small turning circle since all three wheels turn.
More to come when I get another free hour!

Brad
 

Radical Brad

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Making a rear caster from a 32 inch diameter truck wheel is a bit of a challenge, but I managed to do it using only scrap that was laying around here.
Found this 6 inch disc and a piece of sched 40 tube, welded them together and then drilled the largest hole I had a bit for, which was 3/4".
Yep, since the axle I am using is 1 inch diameter, this meant hand filing out the hole. A bit of a task with that half inch thick plate!

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Added a washer on the other side of the tube and then welded the hub to my one inch axle. A spin test showed it was nice and true!

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To drill the studs, I first tack welded the hub to the rim and tested it for balance. It took a few attempts to get the wheel spinning true.
Once aligned, I then used the rim as a drilling template. Hand drill of course, since that's all I own!
Start with a 1/8" bit and then work all the way up to the half inch required for the wheel studs.

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Once the studs were installed, the wheel was set on some pillow blocks for a spin up test.
The alignment is within about 1/8" which is amazing for a hack job using scrap parts!
The Robot is only going to move at walking speed, so this was perfect.

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Next I will mount the wheel to the rear forks.

I shall make the next entry as a real blog on the main site, starting from the beginning of this build and with plenty of detail, including how I narrowed a Jeep differential using only hand tools to recut the spline. No... really, I am that crazy.

Cerberus the Robot shall soon be looking to have a motor installed. I will be using the DC motor from Sparky the Minibike.

Keep on hackin!
Brad
 

Radical Brad

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Took an hour to render up a few 3D views of the robot based on what I have done so far.
Next day off I will have it done up to the point shown in the renders.
Once the frame is welded to the differential I will need to bring it outside closer to my welder, so I have to wait for a non rainy day.

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Can't wait to see how maneuverable it will be with three wheels able to turn.

As for motor ans transmission, I am using the same setup as on the Yard Mule, but with a smaller motor.
The robot sill still be plenty powerful, but unlike the Mule, it does not have to move 2000 pounds up a steep hill.

Blog to come next.
Brad
 

Radical Brad

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Thanks!

All braking will be supplied by the resistance of the motor. With a top speed of "fast paced walk", wheel brakes will not be required since removal of motor power will stop the vehicle within a a foot. Also to note is that the rear steering is not a free caster, it is controlled along with the front steering (unlike the sidewinder recumbent trike).

Brad


With independent brakes on the driven axle (aka 'cutting brakes') it should be able to spin on its own axis, just about! Looking good :)
 

Radical Brad

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Did a bit more work on the triple tree. This beast takes up the entire 8x8 section of my old shack now! This is the only section that has not caved in from rot, so I am not complaining. The frame is not welded to the front diff. yet since it has to move outside very soon. Once welded, Cerberus must live outside until completion.

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It's going to be fun to get this robot running under remote control.
Not sure if I am going to go with high power 5G radios or old school 75 MHz RC links for manual control.
I have both in my collection, and there are pros and cons to both systems.

Brad
 
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