Autonomous Guided Vehicle for Package Delivery

An Arduino-based autonomous delivery robot that navigates a toy environment to collect and deliver packages to designated locations.

System Overview

System Diagram

flowchart TB
    subgraph System["Robot Control System"]
        direction TB
        S[/"<b>Sensors</b><br/>- line sensors<br/>- magnetic sensors<br/>- push button"/]
        Ag["<b>Agent</b><br/>policy π(a|s)"]
        Act[/"<b>Actuators</b><br/>- DC motors<br/>- servo claw"/]
        
        S -->|s_t| Ag
        Ag -->|"a_t ~ π(a|s_t)"| Act
    end
    
    E(("<b>Environment</b>"))
    E -->|"Get physical readings"| S
    Act -->|"Take actions and </br>interact with environment"| E

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Pin Connections

Component	Pin(s)
Line Sensors	Front Left (7), Back (9), Left (10), Right (11), Front Right (12)
Magnetic Sensor	6
DC Motors	Left (2), Right (3)
Servo Claw	13
LED Indicators	Blue (4), Red (3), Green (1)
Push Button	5

Code Structure

The codebase follows an object-oriented design with three main classes:

Sensor Class

• Manages line and magnetic sensor readings
• Maintains buffer of historical sensor values
• Line sensor setup:

Actuator Class

• Controls DC motors for movement
• Operates servo motor for claw
• Manages LED indicators
• Implements low-level motor actions:
  • Forward/backward steps
  • Left/right turns
  • Straight line movement

Agent Class

• Core decision-making module
• Maps sensor states to actuator commands
• Implements high-level navigation strategy

Navigation Strategy

1. Robot follows predefined paths stored in allPaths matrix

2. Each path contains sequence of junction decisions:

   • turn_forward_right/left: Turn at T-junctions
   • step_forward/backward: Move straight
   • straight_forward: Extended forward movement

3. Junction detection:

   • Uses line sensor buffer to confirm consistent readings
   • Increments junction counter when validated
   • Executes corresponding decision at that junction

4. Line following:

   • Error correction based on front sensors

5. Package handling:

   • Magnetic sensor detects package properties
   • LED indicators show package state
   • Servo claw for pickup/delivery

Development Environment

This project uses PlatformIO as the development environment. PlatformIO is an open-source ecosystem for IoT development, industry standard in embedded systems. We use the PlatformIO plugin for VSCode, so that we can compile and build files from VSCode.

platformio

Compared to a project without platformio, the main difference is the platformio.ini file which provides the key configurations for our project.

• lib_deps parameter specifies all the libraries that we'll use in our projects
• upload_port specifies which port of the computer we'll use to connect to the Arduino board, this is usually set automatically but may need to be configured depending on your system

Importing core libraries

Since we're not using the Arduino IDE, we'll have to import libraries ourselves using #include in the main file.

Extra Notes

• Different motor have different speeds
• Thinking blue crosses are junctions
• Serial.Print causes major lags, remove these in the loops
  • After line sensing, delayed action to motors
  • Use a buffer to make readings consistent before making a decision
• Added a double check whenever we encounter |- or -| junctions, make sure its not a cross
• Be careful about using delay! Delay makes it continue the previous action for some time, NOT stop the robot
• Make sure when you upload code or press the reset button, to disconnect the servo AND the motor
  • Otherwise the servo will do a 270deg turn