CHOPP3R is a search-and-rescue helicopter made from a single 31313 Lego Mindstorms EV3 set. I built this as a potential model for a book, but as the book has not materialised I decided to publish it instead! CHOPP3R has working top and rear rotors driven my a medium motor. It searches for a liferaft containing the beacon using the IR sensor mounted under the cockpit. There is a winch mounted on the side to lower a rescue rope that is controlled using the up/down buttons on the EV3. I’m particularly pleased with this model as it looks realistic and yet only uses a single 31313 EV3 set to build. It just shows you that a single set can give you a lot of flexibility.
The Chopp3r.ev3 control program for CHOPP3R is broken into four parts.
- Monitor the touch sensor. If it is pressed then toggle the boolean variable flying
- If flying is true then turn on the rotor motor, otherwise turn it off.
- If flying is true then get the distance reading from the IR sensor and use that to compute the delay between beeps.
- Monitor the up/down buttons and power the winch motor.
To use this model all you need to do is:
- Press the top button on the IR beacon to put it into beacon mode; the green LED in the IR beacon should illuminate.
- Download and run the program on the EV3.
- Press the touch sensor to start the rotors.
- As the chopper gets closer to the IR beacon the beeps will get progressively quicker.
I made building instructions for this model available as a RescueChopper.pdf. Be warned; it’s a 21MB file so best to right-click and Save As… before viewing.
ERRATA: There is a mistake in the building instruction PDF at step 25. Two parts are missing to hold the EV3 onto the Chopper body. You need to attach a Technic Beam 3 x 3.8 x 7 Liftarm Bent 45 Double (part 32009) to both sides of the EV3. See the pictures in the gallery below for details.
CABLES: Connect the cables as follows:
- Motor A: small motor driving the rotors
- Motor D: winch motor
- Port 1: Ultrasonic sensor
- Port 4: Touch sensor