R/C Bot Takes Your Strawberries Away

Don’t let the friendly smile on this RC cart fool you, it will take your strawberries away — though that’s kinda the point. It’s an RC car that [transistor-man] and a few friends modified for carrying freshly picked strawberries at strawberry fields so that you don’t have to.

RC strawberry carrying robot before putting on the cooler
RC strawberry carrying robot – WIP

They started with an older Traxxas Emaxx, a 4-wheel drive RC monster truck. The team also bought a suitable sized water cooler at a local hardware store. A quick load test showed that 5lbs collapsed the springs and shock absorbers, causing the chassis to sink close to the ground. The team had two options: switching to stronger springs or locking out the springs altogether. They decided to replace one set of shocks with metal plates effectively locking them. After that it was time for some CAD work, followed by the use of a water jet to cut some aluminum plate. They soon had a mounting plate for the water cooler to sit in. This mounting plate was attached to 4 posts which originally held the vehicle’s Lexan body. A bungee cord wrapped around the cooler and posts on the mounting plate holds the cooler in place.

Thermal image of bad MOSFET
Thermal image of bad MOSFET

Some initial testing showed that the vehicle moved too fast even in low gear and tended to tip over, as you can see in the first video below. Some practice helped but a 3:1 reduction planetary gearbox brought the vehicle down to walking speed, making a big difference. A trip was arranged to go to local strawberry picking field at Red Fire Farms, but not without some excitement first. At 1AM the UNIK 320A High Voltage Speed controller emitted some magic smoke. A quick check with a thermal-camera found the culprit, one of the MOSFETs had failed, and after swapping it with one that was close enough they were back in business.

As you can see in the second video below, testing in the strawberry field went very well, though it wasn’t without some tipping. Kids also found it a fun diversion from picking strawberries, alternating between mock fright and delight.

They’ve also given some thought to enhancements, such as adding an accelerometer to govern its speed and reduce tipping. Methods for implementing follow-me behavior were also looked into. The team also looked into using a peltier cooler for the strawberries. The peltier but would require a significant cooldown period whereas ice-packs did the job just fine.

Below is some testing while still a little tippy.

And here you can see them testing at the strawberry farm.

Another enhancement we can think of would be to have this beer crate robot bring beer to you to cool you off on those hot strawberry picking days. And to keep picking even through the winter months there’s
[Dino]’s indoor hydroponic strawberry farm, also using a cooler-like container.

16 thoughts on “R/C Bot Takes Your Strawberries Away

  1. Come back here with my strawberries!
    Now we just need a robot with shortcake and that cheese wiz or ketchup robot modified to accept sprayed whip cream.

    Cute robot.

    1. And then he’s going to “BUILD A WALL!”
      lol. I don’t vote for anyone anymore federally. They’re both poor choices IMO.
      Stay local, hopefully less corruption and hyperbole. :/

      p.s. Stock Android can’t autocorrect “coruption”?
      Come on!

  2. Well, i’ve thought sometimes about this, and… I didn’t do it because i dont have the need, it would be only to play, but… since there are 1/5 1/8 monster truck rc that can pull a car (in neutral of course ) i think a wise move would be to do the container as a trailler, and use the monster as a tow truck.. Would lower the CG, would allow, large axles to improve stability.. and shocks… there are a lot of them size, stiffness, etc, eliminate them doesnt seem another good option to me, unless to save money. Besides, if they opt for a trailler, it is possible to use leaf suspension instead of springs as it is/was used in old days heavy trucks..

    Anyway, nice project.

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