How to Build LEGO®-compatible Hexapod Robot

By Tart Robotics |
How to Build LEGO®-compatible Hexapod Robot

Introduction

Legged robots have always been one of the most interesting creations in the robotic industry as they could help us in exploring mysterious lunar caves and other space exploration missions. In fact, legged robots are mobile robots with articulated leg mechanisms that provide locomotion on rough trains. As compared with wheeled robots,  they can move on different terrains, although, at a slower speed.

Legged robots are often complicated to make and control, as it requires precise control of each leg to maintain balance. In this project, we are aiming to make a fun and easy-to-build six-legged robot with LEGO®-compatible components and an Arduino board (Fig A).

To do so, we took advantage of interesting mechanical mechanisms that simulate the walking pattern of a six-legged insect, with only one or two DC gear motors. The result came up pretty interesting and pleasing to watch. Don't forget to follow our step-by-step instructions outlined below, and let us know what you think about this subject by commenting below. Your feedback will help us to improve our future work.

How to build a Hexapod robot with LEGO®-compatible blocks.
Fig A - Electrical assembly

In this tutorial, we will show you how to build a robotic hexapod, a six-legged robot, that can walk similar to an insect (Fig B). You will make the body and the leg mechanisms of the robot using LEGO®-compatible parts. Then, commercially available DC gear motors will be connected to the leg mechanism to move the legs.

In the next step, you will need to add a brain to your robot to control its motions. Therefore, we will use Arduino UNO as an intelligent brain (Fig C). Arduino enables you to expand your hexapod’s possibilities with various commercially available motors, sensors, shields, and modules.

Use Arduino Uno to build Hexapod robot for kids.
Fig B - Arduino UNO

The hexapod is made in two different fashions. The first design uses one DC gear motor to move the hexapod back and forth (Fig D), and the second one is driven by two DC gear motors to enhance the maneuverability of the robot (Fig E).

You can create a Hexapod robot with a DC motor and LEGO®-compatible blocks with your kids.
Fig C - Hexapod with one DC motor
You can create a Hexapod robot with two DC motor and LEGO®-compatible blocks with your kids.
Fig D - Hexapod with two DC motor

You can do a variety of different tasks with your hexapod. You can tell the hexapod to track a path by programming your Arduino board. Add a couple of your favorite sensors or even simply control it with a remote joystick,
similar to an RC car.

What materials do you need to build a Hexapod robot?

There are several electrical parts involved when build a Hexapod robot.
Fig E - List of electronic parts
  1. L298N Mini Motor Driver
  2. Lego-compatible Coupling
  3. Mini Toggle Switch
  4. Bread Boards
  5. Jumper Wire
  6. M3 Nut
  7. M3 Screw
  8. Battery
  9. Yellow Gear Motor
  10. Battery Holder
  11. Arduino Uno
There are several LEGO®-compatible parts involved when build a Hexapod robot.
Fig F - List of LEGO®-compatible parts
  1. Angular block 2, 180°
  2. Double cross block, 3-module
  3. Beam, 3-module
  4. Angular beam, 3x5 module
  5. Beam, 7-module
  6. Beam, 13-module
  7. Frame, 5x7-module
  8. Angular block 1, 0°
  9. Axle, 2-module
  10. Gear, 8-tooth
  11. Bushing, 1/2 module
  12. Gear, 24-tooth
  13. Axle, 6-module
  14. Axle, 3-module
  15. Connector peg, 2-module
  16. Connector peg with friction, 2-module
  17. Connector peg, 3-module
  18. Connector peg with axle, 2-module
  19. Connector peg with friction/axle, 2-module
  20. Bushing, 1-module
  21. Axle connector with axle hole
  22. Beam with crosshole, 2-module

How to use building blocks to assemble the robot?

First, let’s assemble our hexapod’s body and leg mechanisms. Prepare the LEGO®-compatible pieces according to Fig. F, and follow the step-by-step video tutorial below.

What 3D printed parts do you need?

LEGO®-compatible components only match with LEGO®-compatible gear motors. In order to connect the shafts of the commercially available gear motors to LEGO®-compatible components, we need to 3D print a coupling that makes the motor shaft compatible with its LEGO®-compatible counterpart. This is called LEGO®-compatible motor shaft coupling (Fig. G). So, go ahead and download the Lego-compatible Motor Shaft Coupling 3D-print file. Then, find a 3D printer nearby or use yours.

You can download 3D printed parts to build Hexapod robot
Fig. G - 3D printed LEGO®-compatible couplings.
How to use 3D printed parts to build Hexapod robot
Fig. H - General view of LEGO®-compatible gear motor.
You can download 3D printed parts to build Hexapod robot with LEGO®-compatible parts
Fig. I - General view of LEGO®-compatible gear motor.

Electronics and wiring

Grab your screwdriver, warm up your soldering iron, and follow the video instruction below. Don’t forget to carefully implement the circuit diagram, so you don’t end up toasting your precious Arduino board.

How to use electrical parts to create Hexapod robot with your kids
Fig. J - Wiring diagram.

Programming your DIY robot

And last but not least, is the intelligent brain of your hexapod. Although you can do more development with the mechanical and the electrical parts of your hexapod. Programming is indeed the part that you can be most creative at. For now, let’s start with this code.

/*
  Hexapod Walking Robot
    The idea:
    In this tutorial, we will show you how to build a robotic hexapod, a six-legged robot,
    that can walk similar to an insect. You will make the body and the leg mechanisms of the 
    robot using LEGO®-compatible parts. Then, commercially available DC gear motors will be
    connected to the leg mechanism to move the legs.
    The circuit:
    - In this circuit, an Arduino nano is used. Any other types of Arduino
    can be used. Do not forget to change the pin configurations
    if you want to change the Arduino on your preference.
    Visit Tart Robotics blog for more information:
    https://www.tartrobotics.com/blog/all
*/

#define M1 11
#define M12 10
#define M2 9
#define M22 5 


void setup() {
  // Initialize Arduino pins to outputs
  pinMode(M1, OUTPUT);
  pinMode(M12, OUTPUT);
  pinMode(M2, OUTPUT);
  pinMode(M22, OUTPUT);
}

void loop() {
  goForward();
  delay(3000);

  goBackward();
  delay(3000);

  turnLeft();
  delay(3000);

  turnRight();
  delay(3000);
}

// Configures driver motor pins to go forward.
void goForward() {
  digitalWrite(M1, LOW);
  analogWrite(M12, 200);
  analogWrite(M2, 200);
  digitalWrite(M22, LOW);
}

// Configures driver motor pins to go backward.
void goBackward() {
  digitalWrite(M12, LOW);
  analogWrite(M1, 200);
  analogWrite(M22, 200);
  digitalWrite(M2, LOW);
}

// Configures driver motor pins to turn left.
void turnLeft() {
  digitalWrite(M12, LOW);
  analogWrite(M1, 200);
  analogWrite(M2, 200);
  digitalWrite(M22, LOW);
}

// Configures driver motor pins to turn right.
void turnRight() {
  digitalWrite(M1, LOW);
  analogWrite(M12, 200);
  analogWrite(M22, 200);
  digitalWrite(M2, LOW);
}

Run your hexapod robot for your kids