LEGO Mindstorms Beta Rex

The Beta Rex robot is built using only the pieces found in the LEGO MINDSTORMS Robot Inventor 51515 kit. As long as you have this kit, you will be able to build this robot!

LEGO Mindstorms Beta Rex Robot

My goal when designing the Beta Rex was to create a successor to the LEGO MINDSTORMS NXT 1.0 and 2.0 Alpha Rex robots. These robots were awesome walking humanoid robots that showed what’s actually possible with MINDSTORMS. Sadly, since the release of the EV3 system, the walking humanoid robots got replaced with those that used tracks or wheels as their feet, completely eliminating the walking motion.

Walking Humanoid Robot by EV3 System

Fortunately, I have created free building instructions and programs so that you can build this robot yourself! If you remember the old Alpha Rex robots, then you will love Beta Rex! But first let’s go over how to control the LEGO Mindstorms 51515 Beta Rex!

The main program, both the python and scratch 3.0 version, use the hub’s buttons and the color sensor as an input that tell Beta Rex what to do!

LEGO Beta Rex Robot Sensors

If the color sensor detects green, then Beta Rex will enter autonomous obstacle avoidance mode. He will walk forward until he sees an object, then he will randomly turn either left or right, and then he repeat this cycle until the color sensor detects red, which is the color used to stop the robot.

LEGO Ninjago Masters Full Episodes 24/7 Marathon

If the robot detects blue, he will dance once, and then wait for your next command!

If the robot detects yellow, he will grab or release with his right hand! Best of all, you can have the robot enter autonomous obstacle avoidance mode while he is holding an object!

LEGO Mindstorms 51515 Beta Rex

There’s also a full RC version of the program for Beta Rex, so if you want to manually control your robot from your computer, phone or tablet, then simply use the RC code.

Below are three versions of the code, the main scratch 3.0 version, the python version, and the full RC version! Click the button "Download" to get free building instructions and programs!

Build: LEGO Beta Rex Robot


Unbrickme's Beta Rex Instructions:

Unbrickme's Beta Rex (Update):

Unbrickme's Beta Rex (Main Version):

Unbrickme's Beta Rex (Python Version):

Unbrickme's Beta Rex (RC Version):