How to make a small robotic car.

#ai

Lately, I've been thinking about a fun project — building a small robotic cart that can run errands for me. You know, the kind where I just press a button at home and it goes out to buy a bottle of soy sauce. Sounds pretty cool, right? I figured I’d put together a list of stuff I need and document the build process to share with everyone.

First, a shopping list:

The brain (main control board), with WiFi and Bluetooth, so it can go online easily.

The body (chassis and wheels)

4x N20 geared motors, with wheels included.

A motor driver board — basically the muscles that make the robot move.

Either tracks or regular wheels, just depends on what you like.

Power system

Batteries: 2x lithium batteries.

A battery holder, the kind with wires attached.

A switching power supply module: a step-down module to convert the battery voltage to a stable level for all the parts.

A charging module with protection, to keep the batteries from overcharging.

Control button

A 16mm latching button switch with an LED, used to start/stop the shopping task. Press once to turn on, press again to turn off. About 15 bucks.

Sensory system

A camera, for recognizing the road and items.

An ultrasonic sensor: for obstacle avoidance, so it doesn't run into walls.

The shell

A 3D-printed shell, or I could cut one myself from acrylic sheet.

Time to get building:

Step 1: Build the frame
First, mount the motors onto the chassis, then put the wheels (or tracks) on. N20 motors have screw holes, so just screw them on tight.

Step 2: Wiring
Connect the motor driver board to the ESP32. This part needs to be done carefully, plugging in the main signal wires according to the circuit diagram. Then, connect the LM2596 module to the battery holder and adjust the voltage (usually to 5V and 3.3V). Finally, connect the L19 button to a GPIO pin on the ESP32 to control power on/off.

Step 3: Install the brain
Secure the ESP32 main board in place, then connect the camera and the ultrasonic sensor. The camera should face forward, and the ultrasonic sensor should point a little bit forward and down.

Step 4: Write the code
Install the Arduino IDE on the computer and add the ESP32 board support package. The basic logic of the code will be something like this:

Press the L19 button, the system starts.

The camera starts recognizing the path, and it moves forward.

If the ultrasonic sensor detects an obstacle, it goes around.

When it arrives at the destination, it identifies the item to buy.

After buying, it comes back on its own and goes into standby.

Step 5: Put on the shell
Tidy up all the messy wires, snap the outer shell into place, and secure it with hot glue. It’ll look much cleaner.