Project Specification

Project IUGV: a three-wheeled differential drive UGV

Unmanned ground vehicle for remote area inspection with three-wheeled differential drive.

Specifications

Designing SoftwareAutodesk Fusion 360, Ansys, ROS
Mechanical Parts3D printed; PLA (500g)
MicrocontrollerStepper motor: ATmega
DC motor: Raspberry Pi
DC motorDC Geared Encoder Motors
Stepper motorNEMA 17 stepper motor
CameraIntel D435i stereo depth camera
PowerLypo battery and charger
WheelsRear wheels and caster wheels
Operating SystemROS 2

Overview

Problem / Solution

Robots are widely used in various industries to improve everyone's lives. Robots are constantly evolving and revolutionizing the industry, society, and daily human lives. Furthermore, robots handle repetitive work, hard lifting, hazardous materials, and risky jobs humans would otherwise have to perform. Robots have helped businesses avoid numerous incidents while saving them money and time. Mobile robots are a subcategory of robotics that include sensors controlled by software and artificial intelligence. Additionally, the software controls these sensors, allowing it to recognize and navigate its environment and carry out various tasks. Robots are used in multiple settings, including customer service, warehouse work, remote area inspection, and order fulfillment.

Project IUGV aims to design, prototype, and automate an unmanned ground vehicle (UGV) that can inspect remote areas. The robot created is a three-wheeled differential drive UGV prototype assembled after being created on a 3-D printer.

Design

The paper used different 3-D modeling software such as Autodesk Fusion 360, Ansys, and ROS. The paper also used hardware such as 3D printing the mechanical parts, electronics (RPi, Arduino Nano, etc.), DC geared encoder motors, NEMA 17 stepper motor, and Intel D435I camera to complete the design.

 

Mechanical

To improve strength and performance while using the least amount of material possible, Project IUGV used a generative design to create the UGV. It joins the UGB's caster wheel to the chassis front portion. Additionally, the IUGV project uses 3-D printed and assembled components. The project utilized 3-D printers: Maker-Bot for minor parts and Pratham 3.0 for large parts. A total of 500 gms of PLA filament are used for the project. The project's methodology has shown to be a workable approach that produces lasting components.

 

Electronics

Register Based Programming

Instead of relying on layers of abstraction for based programming, it seeks to write directly to the microcontroller's registers by doing some manipulation to obtain the required effects.

Serial Communication between RPi and Arduino

According to the study, an ATmega microcontroller is better suited to controlling the stepper motor. Additionally, this microcontroller has many ADC ports that can be used to measure the current LIPO voltage. RPi presents difficulties because it requires 3.3V operation and a separate IC to operate. As a result, it was found in the paper that the Atmega and RPi use the USART protocol to exchange the necessary data. The RPi is also in charge of controlling the DC motor speed.

PI Motor Speed Control

The difference between a system's output and a predetermined set point is utilized as the basis for the error signal calculation by a PI controller acting on a feedback loop. The system's output is moreover determined by the motor shaft speed. Additionally, the PWM on a matching RPI GPIO pin is tied to the motor speed. The RPi also uses software PWM on each and every pin.

Battery measurement

The design selected batteries with a better power density and a lower weight for the battery measurements. The report also found that the battery's price is inversely correlated with its power capacity and density. The chemistry employed inside a battery cell also affects the cell's voltage. Alkaline batteries are 1.5 volts, all lead acids are 2 volts, and lithium is 3 volts. Additionally, the batteries can only be recharged 100 times and are occasionally rechargeable.

Perfboard

It is a good material for electronic circuit prototyping (DOT PCB). The perfboard is a thin, rigid sheet with pre-drilled holes arranged in a grid at regular intervals. The pad is additionally electrically isolated. The builders link everything using microscopic point-to-point wiring methods or wire wrapping. Discrete components integrated onto the prototype board include resistors, capacitors, and integrated circuits.

Motors with encoders

An electric motor is fitted with a rotary encoder that tracks the rotational speed and location of the motor shaft to generate closed-loop feedback signals. Encoders also use mechanical motion to produce an electrical signal, which the control system operates to track particular characteristics.

 

Robot Operating System (ROS)

The ROS 2 robot operating system employed in the design can significantly simplify the hardware-software interaction. Furthermore, because ROS 2 is extensible and built on top of DDS/RTPS, it may be utilized for real-time, high-level system integration and embedded device applications.

References

Arvind Kaushik, Praneeth KVK, Rikin Ramachandran, Mukul Yadav, Manas Reddy, Juvvi Manas, Anshika Lodha, Chirag Agrawal, Rohith Narayan, Tanmay Sinha, Vedant Nath

Wevolver 2022