Unmanned Ground Vehicle (UGV)

 

Tech Stack

 

 

Budget

 

 

Technical Drawings

 

Mobile Platform Base

·         The platform bases are designed like a pegboard to make the UGV more modular, and they’re manufactured from acrylic using a laser cutter

o   This design facilitates designing and fastening peripheral mounts/attachments and flexibly position them as needed

o   The platform bases are manufactured from acrylic for the material’s low conductivity and ability to withstand heat, thereby reducing unintended influence on electronic components

o   Laser cutting the design onto an acrylic sheet allowed for consistent and accurate cuts

·         Laser Cut at Maker FX Maker Space on Boss Laser LS-1630

 

Raspberry Pi 4 Model B Mounting Block

·         3D Printed at Orange County Library – Melrose Center Maker Space on Bambu Lab A1 printer

 

Breadboard Mounting Plate

·         Breadboard dimensions: 3.25” X 2.125”

·         Breadboard comes with adhesive sheet to adhere to mounting plate

·         Laser Cut at Maker FX Maker Space on Boss Laser LS-1630

 

6V Battery Mounting Block

·         Rev A:

o   Fastener head clearance too tight

o   It is difficult to remove battery box from mounting block without flipping upside down

§  Needs space to fully grip battery box for removal from mounting block

·         3D Printed at Orange County Library – Melrose Center Maker Space on Bambu Lab A1 printer

 

DC ‘TT’ Motor

·         DC ‘TT’ Motor assembly file from GrabCAD, as indicated in drawing notes

·         Technical drawing by me

 

DC ‘TT’ Motor Mounting Block

·         Only the right drive motor mount was modeled, so the model was mirrored in the Bambu Studio slicing software when 3D printed to produce the left drive motor mount

·         3D Printed at Orange County Library – Melrose Center Maker Space on Bambu Lab A1 printer

 

L298N Mounting Plate

·         Laser Cut at Maker FX Maker Space on Boss Laser LS-1630

 

SG90 Servo Motor Mounting Block

·         Rev A

o   The mounting block is designed to fasten to the servo motor via two M2.5x5+6mm standoffs, so the print will be 5mm too short for a motor to sit directly in the saddle without standoffs

·         Rev B

o   Added missing width dimension in drawing

o   Taller standoff supports clearing fastener heads and motor wires’ bend radius

o   Narrower standoff supports improving servo fit in mount saddle

o   Standoff support thread holes’ diameter increased from 2.1mm to 2.2mm

o   Use M2x5+3mm standoffs to fasten servo motor to mount

·         3D Printed at Orange County Library – Melrose Center Maker Space on Bambu Lab A1 printer

 

 

ESP32 UWB DW1000 Housing

·         Made of clear acrylic so that pin labels and LCD (if present) are visible

·         2 housing plates per module:

o   Top (side with LCD, if present)

§  M2.5 x 10mm standoffs

o   Bottom (side with pinout labels), OPTIONAL

§  M2.5 x 15mm standoffs

·         Laser Cut at Maker FX Maker Space on Boss Laser LS-1630

 

 

Pictures of Manufactured and Assembled UGV

 

 

Mechanical

 

·         More technical information about motors can be found in my Motors Tech Notebook.

·         Code for driving motors with Python on the Raspberry Pi can be found in my github:

o   Raspberry Pi Motor Hat Driver

o   L298N Motor Driver Demo

o   SG90 Servo Motors

 

DC Gear Box Motor – DC ‘TT’ Motor

 

Technical Specifications

 

 

 

SG90 Micro Servo Motor

 

Technical Specifications

 

 

Electrical / Electronics

 

Raspberry Pi 4 Model B

 

 

L298N Motor Driver

·         The DC motors are rated for a voltage that exceeds what a microcontroller outputs

·         A motor driver provides the motors with an external power source that meets the motor’s specifications but receives logic signals from the connected microcontroller

·         The L298N microcontroller has H-bridge and Pulse Width Modulation (PWM) capability, controlling the motor’s output effort (i.e. rotation speed) and direction

 

 

·         The diagram below shows how the L298N motor driver is connected to the DC motors and the microcontroller logic pins

 

·         Code for driving motors on the L298N motor driver with Python on the Raspberry Pi can be found in my github:

o   L298N Motor Driver Demo

 

 

Ultra Wideband (UWB)

·         Ultra-Wideband (UWB) is a high-precision, short-range wireless radio technology used for accurate, low-power device localization at short distances

o   Devices send multiple short radio pulses over a wide frequency band and measure the time it takes for signals to travel between one another (Time of Flight, ToF) to determine their distance and position

o   Large bandwidth provides high data rates and stability to reduce interference while enabling precise positioning

§  Ideal for indoor positioning and navigation

 

 

·         These modules can communicate with the microcontroller using Universal Asynchronous Receiver/Transmitter (UART) protocol, an asynchronous serial communication for short-distance wired communication

o   See Communication Protocols: UART in Tech Notebook

 

ESP32 UWB Pro with DW1000

 

 

 

The ESP32 documentation defines the pinout for the chip that’s soldered on Makerfab’s board.  The board pins map to the ESP32 chip pins with the corresponding name, as defined in the documentation.

 

 

 

 

Algorithms

 

·         All algorithms implemented in this UGV are documented in the Tech Notes section of my digital notebook!

o   Localization: Trilateration

o   Path Planning: A* Path Planning

 

 

Software

 

·         All code implemented in this UGV is publicly available on my github!

o   Localization

o   Path Planning

o   Raspberry Pi Motor Hat Driver

o   L298N Motor Driver Demo

o   SG90 Servo Motors

o   ESP32 UWB Pro Demo

Helpful Links

·         Ultra Wideband Sensors

·         Makerfabs ESP32 UWB with DW1000

·         ESP32-WROVER Documentation