String Racing Robots are Here !

This could be the start of a new thing. [HarpDude] showed off his String Car Racers over on the Adafruit forum. It’s like a small model cable car on caffeine. String up enough of them and go head to head racing with others.

A motor with a small pulley runs over a length of string stretched between 2 posts. Below the pulley, acting as a counterweight balance, is the rest of the racer. A Trinket board, motor driver, 9V battery and a pair of long lever micro switches to detect end of travel. The switches also help reverse the motor. A piece of galvanized wire acts as a guide preventing the String Car from jumping off the string. And discovering the benefits of a micro-controller design, as against discrete TTL/CMOS, old timer [HarpDude] added two operational modes via software. “Pong”, where the String Car keeps going back and forth over the string until it stops of (battery) exhaustion. The other mode is “Boomerang” – a single return trip back and forth.

We are guessing the next upgrade would be to add some kind of radio on the car (ESP8266 perhaps) and build an app to control the String Car. That’s when gaming could become fun as it opens up possibilities. One way to improve performance would be to add two “idler” pulleys in line with the main drive pulley, and then snake the string through the three of them. Now you know what to do with all of those old motors you’ve scavenged from tape drives, CD drives and printers. Let the Games begin!

Thanks [Mike Stone] for tipping us off on this.

24 thoughts on “String Racing Robots are Here !

  1. Yeah, definitely needs an ESP8266 to offload all that heavy computing to a desktop pc :)
    How about just a battery and a DPDT rocker with a long lever to detect ends and reverse the motor? You still need the motor though.

  2. “racing robot” ??? Sure. and my e-cig is a not less than a FRICKING “glycerol steam engine”, Are my shoes are “smart skin” btw.

    Still no article about a string phone.

    Seriously, do you guys get paid for writing such … “articles” ? Really ?

    1. Two outer idler pulleys could be lifted/pushed up/down by a servo to increase string path. Racing robot would then lift up and avoid detected obstacle(s) below.

      Wow – bad day in the troll basement ‘bin’ ?? Did Mommy not make you lunch or what? They’re not a Fanuc, but they do race and they’re robots. Give it a break.

      Great hacking opportunity.

  3. You could use proximity sensors to detect the ends and do a slow reverse. I was also thinking if you had feedback from the motor you could control the torque and manage the slip. This would yield much better battery life (minus the 1ghz CPU to run it :)

    1. Actually the possibilities are endless. Just need to think creatively outside the box. How about the robots need to drop a ‘bomb’ on/into target below.

      Soft Start/End
      Relay Race On Same String
      Steep Climbing
      Obstacle Avoidance
      Direction Reversal
      Jousting w/ Second Line Racing Robot
      Firing Projectile at Target While Line Racing Robot is Moving
      Target Capture
      Battery Optimization
      Payload Drop

      Could be VERY exciting code!

  4. add a revolution counter, simple camera, claw arm or hoist, and lift and stack things for Great Good! Tower of Hanoi contests. A container terminal for my model railroad! (oops, said too much)

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