Battling 'robots' made from cheap toys

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Cheap RC Toys + Powertools + Hobby/Hacker Electronics
deathbots, the poor man's Battlebots/Robot Wars

Thrift store find RC cars are great. Typically cheap because they are missing a remote, or have a damaged receiver/driver board.

Arduino, Raspberry Pi, I2C breakouts, and other components are so readily and cheaply available that restoring life to these toys is now more accessible than ever.

Currently, we're working on the reanimation of each vehicle, and remote control. Following that comes the weapon-design phase.

There are two chassis in development, a rock-crawler and an excavator. Additional robots will be built in time as more chassis are added.

Yes, I know they're not technically robots, just RC toys... but that never stopped the TV series from calling them robots either.

This is ***ABSOLUTELY A DANGEROUS IDEA***. If you choose to try this yourself, I am not responsible for your results.

Currently we have two chassis.  

  • tracked excavator hull with the bottom-most portion of it's digger arm remaining
  • off-road "rock-crawler" style with a futuristic buggy shell

Both have motors, radio receiver boards, motor drivers, etc.

The tracked chassis is a skid-steer, obviously.  The rock-crawler style chassis has more traditional car-type steering.  For toy-grade rc cars, this typically means a small brushed DC motor with geartrain and torque-limit device (servo-saver in hobby parlance).  I've designed and 3d-printed an adapter for a hobby servo to (hopefully) replace this complex geartrain and full-swing-only steering.  The servo arrived, and I've been hacking away at the plastic structure with a dremel, test-fitting, and rolling ideas in my head about the 3d printed portion to come.

Both run on small brushed DC motors, and a direct-swap to hobby-style (540 can size) motors does not look straightforward.  However, in hacking the steering, I have now freed one motor that looks to be a direct replacement (same pinion, except in metal!) for the drive motor.  I have also removed the front-axle's motor and drivetrain, converting the vehicle to 2wd for now.

Common arduino motor driver shields are in testing currently.  I have also considered using an i2c PWM controller with a hobby ESC.  My concern is that most hobby ESCs pass a fair amount of current when prompted, and I may find myself repeatedly fragging these small brushed motors.

As for armaments, this is still very much a "drafting table" part of the project.  Scratch-built options, such as a brushless outrunner powered flail will consume a considerable amount of design time.  Off-the-shelf solutions, such as a modified cordless saw will require balancing size/power with the chassis' capability to carry it.

Controls may require an off-the-shelf replacement or custom-built solution.  Bluetooth gaming controllers are a very attractive option, with the low-cost of BT receivers.  Range is a concern, however the robots will likely be no more than 5 to 6 feet away from their operator at any time.

Lastly, fail-safes.  As we will be writing the software for each robot as it is developed, the mantra of "When this goes completely wrong, how do we stop it?" is repeated throughout.  A cordless saw mangling a lithium cell rapidly turns into a completely destroyed robot and using a fire extinguisher once the reaction has run its course.  Shorted components during battle must be met with existent and novel solutions.  Appropriately fusing the primary power source for both drive/control and weapon is a MUST.  In addition, weapons should default to idle/off.  Should the robot's control systems become too badly damaged to respond to commands, all weapons and drive systems MUST fail to idle/stop.

  • 1 × RC Toy Whatever you find at the thrift store, your choice here determines the layout of your robot
  • 1 × "Robot Controller" Your choice, could be a Arduino, PIC, ARM, SBC, whatever
  • 1 × RC Electronic Speed Control (brushed motor application) PWM-controlled high-current motor driver, standardized and cheaply available
  • 1 × RC Servo (as needed) PWM-controlled high-torque/speed positioning servo
  • 1 × Bluetooth HC-05 or HC-06 Radio-serial interface to controller logic from smartphone or tablet.

View all 9 components

  • name this robot

    Floz02/10/2018 at 21:16 0 comments

    The excavator chassis rapidly earned the name Gargoyle.  Partly because it kept the cats away from my desk, even when powered down.

    With the addition of the rock-crawler, it's time to name a robot.

    I'm putting this out to the HaD community, suggestions are welcome.  The more creatively offensive, the better.

  • skid-steer controller

    Floz02/10/2018 at 20:46 0 comments

    This is one option I'm testing for skid-steer on the excavator.  Currently it uses it's stock motor drivers, which are being monitored by the on-board arduino.

  • ...and in the blue corner, this guy!

    Floz02/10/2018 at 20:45 0 comments

    New chassis, a rock-crawler this time.

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Floz wrote 01/04/2019 at 07:08 point

Going to do a total rebuild of both robots this year and hopefully add weapons.

  Are you sure? yes | no

Floz wrote 04/14/2018 at 00:40 point

Slowly but surely building the electronics package for the buggy bot.

So far it's an arduino uno clone with a i2c pwm breakout, and some protoboard for power/ground distribution.  The pwm breakout controls a hobby esc and servo.

Bit by bit, it's coming back to life.

  Are you sure? yes | no

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