Course Lesson 3 of 10: Assembling Raspberry Pi Pico 4WD Smart Car Kit from SunFounder by Robojax

Course Lesson 3 of 10: Assembling Raspberry Pi Pico 4WD Smart Car Kit from SunFounder by Robojax

Introduction

This guide walks you through the complete physical assembly of the SunFounder Raspberry Pi Pico 4WD Smart Car Kit, as demonstrated in Lesson 3 of the Robojax course. This project is your gateway to building a fully functional, programmable robot car. By the end of this assembly, you will have a robust hardware platform ready for a wide range of programming and control experiments.

This isn't just about putting parts together; it's about understanding the mechanical and electrical foundation that makes your car's future capabilities possible. The car you're building is designed to be controlled via a mobile app, offering features like forward/backward movement, turning, and headlight control. It also includes sensors for more advanced autonomous behaviors.

Once assembled, your smart car can be used for a variety of projects, including:

• Obstacle Avoidance: The ultrasonic sensor allows the car to detect and navigate around objects in its path, creating a truly autonomous rover.
• Line Following: Using the grayscale sensor, the car can be programmed to follow a black line on a white surface, a classic robotics challenge.
• Hand-Following Robot: By utilizing the ultrasonic sensor's distance readings, you can program the car to follow your hand at a set distance.
• Cliff Detection: The downward-facing sensors can be used to detect edges and prevent the car from driving off a table or ledge.
• Speed and Distance Measurement: The encoder wheels and photo-interrupter sensors allow you to measure the car's speed and distance traveled, which is essential for precise navigation.

This assembly guide will take you step-by-step through mounting motors, sensors, and the main control board, ensuring a solid and correctly wired foundation for your future coding adventures.

Hardware Components

Before starting, it's crucial to have all the components from the kit organized. The video emphasizes the importance of having all the small pieces ready. Here is a list of the primary components you will be assembling:

• Raspberry Pi Pico board
• 4WD Car Chassis (upper and lower plates)
• 4x DC Motors with gearboxes
• 4x Wheels
• Ultrasonic Sensor Module
• Grayscale (Line Tracking) Sensor Module
• RGB Light Module
• Servo Motor
• Battery Holder
• Encoder Wheels and Photo-Interrupter Sensors (for speed detection)
• Various screws, nuts, rivets, and standoffs (as detailed in the video)
• Jumper wires (various lengths and colors)

Wiring Guide

The video transcript provides a detailed, step-by-step assembly process. While the primary focus of this lesson is physical assembly, it also covers the initial wiring of the sensor modules to the main board. The key wiring steps are highlighted below.

For a visual representation of the complete circuit, please refer to the diagram below.

Grayscale Sensor Wiring

This module is connected using a 5-wire cable. The wiring is straightforward, with power and ground in the middle and three signal wires on the side.

• Black Wire: Connected to the ground (GND) terminal.
• Red Wire: Connected to the middle terminal, which provides power (VCC).
• White, Brown, and Yellow Wires: These are the three signal wires for the sensor's individual channels (as seen in the video at 24:30).

RGB LED Module Wiring

The RGB module uses a 4-wire cable. The video shows connecting it with matching colors: black, red, orange, black, red, and yellow. The video notes that the module is labeled "N" (for input) and "DO" (for output). The cable should be connected to the "N" (input) side of the module, and the wires are connected to the corresponding pins on the control board (in video at 25:06).

Ultrasonic Sensor Wiring

The ultrasonic sensor is connected using a 4-wire cable with yellow and white signal wires. The video demonstrates connecting it to the last row of pins on the board (in video at 30:28).

• Yellow Wire: Connected to pin 6 (Trig).
• White Wire: Connected to pin 7 (Echo).
• Red and Black Wires: Connected to the middle pins for power (5V) and ground (GND).

Assembly Steps

The assembly process is detailed and methodical. Here is a breakdown of the key stages as presented in the video, designed to be followed sequentially. The instructor emphasizes checking the orientation of parts and ensuring a snug fit throughout the process.

1. Preparing and Mounting Sensor Modules

The assembly begins with preparing the smaller sensor modules. The instructor first connects cables to the RGB module, ensuring the cable is inserted into the "N" (input) side. The module is then mounted to the car's chassis using small rivets, with careful attention to the direction of the cable holes (in video at 02:46).

Next, the grayscale sensor module is prepared. A potentiometer is inserted into its designated hole on the module, and it is then mounted to the chassis using larger rivets (in video at 06:39).

2. Motor Installation

The four motors are then installed. A crucial detail here is the orientation of the motor's wires; they must always face the inside of the car chassis. A special piece is used to hold the motor in place, and a curved metal bracket is attached with long screws. The instructor stresses that the curve of this bracket must face the motor body, not the shaft (in video at 07:13).

After all four motors are installed, the instructor labels them (Front Left, Front Right, Rear Left, Rear Right) to avoid confusion during later wiring (in video at 10:05).

3. Attaching Encoder Wheels and Sensors

For speed detection, an encoder wheel is attached to the back of the car's drive shaft. A photo-interrupter sensor is then mounted from the bottom of the chassis, and the encoder wheel is carefully positioned to pass through the gap in the sensor without touching it. The instructor uses a screwdriver to adjust the wheel's position to ensure it spins freely (in video at 10:54).

4. Mounting the Battery Holder and Standoffs

The battery holder is mounted on the top plate of the chassis. The ribbon cable from the holder is threaded through from the top to leave enough length underneath for connection. It is secured with screws and nuts (in video at 13:07).

Next, four standoffs are attached to the top plate. These will serve as the mounting points for the main control board (in video at 15:45).

5. Servo Motor and Ultrasonic Sensor Assembly

The servo motor is attached to a dedicated mounting board using rivets. This assembly is then secured to the front of the car chassis using standoffs and screws (in video at 17:25).

A mounting bracket is attached to the servo's horn. The ultrasonic sensor is then fixed to this bracket, facing upwards. The entire assembly is then carefully inserted onto the servo's shaft, ensuring it is straight (in video at 28:39).

6. Final Wiring and Board Installation

Before installing the main board, the instructor passes all the motor and sensor wires through the chassis to keep them organized. Then, the Raspberry Pi Pico board is inserted into its designated slot on the control board, with the USB port facing a specific direction (in video at 23:01).

The wiring for the grayscale, RGB, and ultrasonic sensors is completed as described in the Wiring Guide section above.

7. Attaching the Wheels

Finally, the wheels are attached. The instructor notes that it's important to hold the car's drive mechanism firmly from the inside to prevent it from separating when pushing the wheel on. After securing all four wheels, the assembly is complete (in video at 31:19).

Code Explanation

As this is an assembly lesson, no code is provided or explained in this video. The focus is entirely on the physical construction of the car. The programming and software setup are covered in subsequent lessons of the course.

Live Project Demonstration

This lesson is dedicated to the physical assembly of the car. The video concludes with a fully assembled 4WD smart car, ready for the next steps of programming and testing. The successful completion of this assembly is the critical first step toward bringing your robot to life. The next lessons in the course will cover the necessary code and control logic to make the car move, avoid obstacles, and follow lines.

Chapters

• [00:00] Introduction and Course Overview
• [02:46] Assembling the RGB and Grayscale Sensor Modules
• [07:13] Installing the Four DC Motors
• [10:54] Attaching Encoder Wheels and Speed Sensors
• [13:07] Mounting the Battery Holder and Standoffs
• [17:25] Assembling and Mounting the Servo and Ultrasonic Sensor
• [23:01] Installing the Raspberry Pi Pico Board and Wiring Sensors
• [31:19] Attaching the Wheels and Final Assembly