Introduction: Crabot

The Crabot is an engineering project for people who want to learn more about electrical engineering, Arduino coding, and robotics. It is also meant for further experimentation, improvement, and fun!

Step 1: Build the MBot

The first step is to build the mBot. The kits can be bought on the Makeblock website, or can be found on Amazon. For this project, leave out the provided ultrasonic sensor, but if you want to build the entire robot first and play around with it, go right ahead! That's what I did! For more information on the mBot visit their website.

Step 2: 3D Print All Pieces

Download the stl. files of the claw and the servo holder, and choose a filament color for each. My claw is blue and my holder is black, but they can really be any color you want! Make a Tinkercad account if you don't have one, because you'll need it if you will want to edit the files.

Open the files in a Makerbot program, or any other 3D printing program you have, and start printing! It shouldn't take longer than two hours, altogether.

***The print design was based on a pre-existing design by Jon Goitia (thank you so much!), who made a super easy-to-make claw to hold a can of Red Bull. I took his design and made the claw larger, but if you would like your robot to hold a can of Red Bull, go ahead and use his design! (Also check out his robot that he made entirely from scratch, which is pretty cool!)

Step 3: Assemble the Claw

Screw the claw onto the servo using small screws and supports.

**Do not use big screws! They may break your servo!**

I used bolts and washers as supports but you can be creative! There are a bunch of ways (probably better ways) to assemble the claw.

Step 4: Arduino Wiring: Servo and Ultrasonic Sensor

I bought my Arduino Uno kit on Amazon, but the kit does not include an ultrasonic sensor, so you will have to buy that separately.

To set up the wiring you must first create a circuit:

  • (Red-- 5V to +)
  • (Black-- GND to -)

This will power the rest of the breadboard and enable the servo (the claw) and the ultrasonic sensor (the "eyes" of the robot) to be connected to power.

To connect the ultrasonic sensor:

  • (Short Black-- GND to -)
  • (White-- Echo to 6)
  • (Green-- Trig to 5)
  • (Orange-- Vcc to +)

To connect the servo:

  • (Black-- to -)
  • (Yellow/White-- to 2)
  • (Red-- to +)

** The colors of the wires do not matter that much, but generally people stick to making GND black and 5V red. The rest of the wires can be any color.**

Step 5: Upload the Code

Connect the Arduino Uno to a computer and download the Arduino software. Once you have done this, copy and paste the code into the program:

This is the code.

When the ultrasonic sensor detects an object 15 cm away, it opens the claw, then closes and waits for 10 seconds, then opens and closes again. These numbers can be changed in the code.

Step 6: Have Fun!

The last step is to have fun with it!

As this is my first engineering project, the model is far from perfect and can use a significant amount of improvement. Nevertheless, it is the challenge that makes it fun and interesting!

Things to try with this robot:

  • Try to align the robot with an object and wait till the claw opens. Once it does, use the remote control to drive it in and grab the object! Grab it, Crabot!
  • Use the line follower setting on the mBot and combine trying to grab an object while staying on course!
  • Try changing the code to make the Crabot hold objects longer or grab them faster!

If you want to see my process for coming up with this project, visit my google sites page.

Hope you make it!