Design a Laser Cat Toy

In this DIY project, we will create a simple and fun laser cat toy!

This project uses two servos, a NodeMCU, and a 9V battery to control a laser that moves around in a random pattern, keeping your cat entertained for hours.

The laser is mounted onto a 3D-printed arm and housing, making the setup sturdy and visually appealing.

Supplies

There are only a few things you will require:

NodeMCU – Or a similar Arduino module
Two 9G servos
9V battery and battery clip
Laser toy – Make sure it has a clip or a method to secure it onto the arm (You can find lots of these online for cheap)
Jumper wires
M2*8 Screws – You will need a few of these to secure the servos and 3D-printed arms together.
M2 Nut – You will need two of these to secure one of the servos to the Base.
M4*8 Screws – You will need four of these to secure the Base Cover onto the bottom of the housing.
3D Printer & Filament – You will need access to a 3D printer and some filament to print the cat toy housing.

Step 1: 3D Printing

I designed the housing in Fusion 360 and printed them using white PLA.

The design consists of four main parts.

Base.stl – This is where the electronic components will be stored
Arm Bracket.stl – This allows the Z rotation.
Laser Holder.stl – This holds the laser and allows the X rotation.
Base Cover.stl – This covers the bottom of the base and protects the electronics.

I used the following print settings:

Infil: 20%
Layer height: 0.28mm
Supports: Yes (Specifically: Tree Supports)

Attachments

Step 2: Assembly

There are only a few steps required to assemble the entire cat toy.

First, mount one of the servos into the Arm Bracket and secure it using M2 screws.

Then, using two M2 Screws and Nuts, secure the other servo to the Base by slotting it into the allocated slot. (Make sure that the gear of the servo motor is in the centre)

Afterwards, secure the Laser Holder to the servo arm of the Arm Bracket by using M2 Screws.

Do the same thing by screwing the Arm Bracket into the servo arm of the Base.

Finally, thread the Servo cable from the Arm Bracket through the hole in the Base.

Now you should be complete with the assembly!

If you are confused, please look at the images above for some clarification!

Step 3: Wiring

The wiring of the Cat Laser Toy is simple, you can either follow the Fritzing diagram above or read the wiring diagram below.

9V Battery – NodeMCU

Positive (+) – VIN
Negative (-) – GND

X-Axis Servo Motor – NodeMCU

Positive (+) – 3.3V
Negative (-) – GND
Signal -D6

Z-Axis Servo Motor – NodeMCU

Positive (+) – 3.3V
Negative (-) – GND
Signal -D5

Step 4: Code

How it works:

The code works by controlling the two servos to move the laser in random patterns.

In the main loop, the code generates random target positions and speeds for the servos within predefined limits.

After each movement, the code introduces a random delay, before the next movement occurs.

Adjusting the Angle Limiters:

Within the code, there are limiters in place so the Servo only draws the dot within a specified range.

You can customize the range of motion for each servo by adjusting the angle limiters in the code. This allows you to control how far the laser can move horizontally and vertically. Modify the minAngleX, maxAngleX, minAngleZ, and maxAngleZ variables to suit your preferences.