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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 be made and controlled, as it requires precise control of each leg to maintain its balance. In this project, we are aiming to make a fun and easy-to-build four-legged robot with Lego-compatible and an Arduino board. To do so, we take advantage of interesting mechanical mechanisms that simulate the walking pattern of a real animal, with only one DC gear motor. The result is quite interesting.

In this tutorial, we will make the body and the leg mechanisms of the robot using Lego-compatible parts. Then, an off-the-shelf DC gear motor will be connected to the leg mechanism to move the legs.

In the next step, we will need to add a brain to our robot to control its motions. Therefore, we will use Arduino Nano as an intelligent brain. Arduino enables us to expand our Quadruped’s possibilities with various commercially available motors and sensors.

List of electronic parts

A) TT Gear Motor
B) 3D Printed Gear Motor Housing
C) 1x Arduino Nano
D) 1x Breadboard, Mini Size
E) 1x Power Jack, Barrel Type
F) 1x Ultrasonic Sensor
G) 3D Printed Lego-compatible Coupling
I) 1x M3 x 25 Machine Screw
J) 2x M3 x 10 Machine Screw
List of Lego Technic components
A) Frame, 5x7 module
B) Gear, 40-tooth
C) Gear, 24-tooth
D) Gear, 20-tooth and double bevel
E) Bevel gear, 12-tooth
F) Gear, 8-tooth
G) Beam, 9-module
H) Beam, 5-module
I) Beam, 3-module
J) Angular beam, 3x5 module
K1) Axle, 7-module
K2) Axle, 6-module
K3) Axle with stop, 4-module
K4) Axle, 3-module
L) Bushing/axle extender, 2-module
M) T-Beam, 3x3 module
N) Angular block 2, 180°
O) Connector peg with friction, 3-module
P1) Connector peg with friction, 2-module
P2) Connector peg with friction/axle, 2-module
Q) Beam with cross hole, 2-module
R) Double cross block, 3-module
S) Bushing, 1-module
T) Axle and pin connector perpendicular
U) Connector peg with axle, 2-module
V) Bushing, 1/2 module
W) Angular block 1, 0°
X) Axle connector with axle hole
Y) Angular block, 6 (90°)
Z1) Liftarm, 2 x 4 L-Shape Thick
Z2) Universal Joint 3L
Z3) Axle, 2-module”

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