Book Image

ROS Programming: Building Powerful Robots

By : Anil Mahtani, Aaron Martinez, Enrique Fernandez Perdomo, Luis Sánchez, Lentin Joseph
Book Image

ROS Programming: Building Powerful Robots

By: Anil Mahtani, Aaron Martinez, Enrique Fernandez Perdomo, Luis Sánchez, Lentin Joseph

Overview of this book

This learning path is designed to help you program and build your robots using open source ROS libraries and tools. We start with the installation and basic concepts, then continue with the more complex modules available in ROS, such as sensor and actuator integration (drivers), navigation and mapping (so you can create an autonomous mobile robot), manipulation, computer vision, perception in 3D with PCL, and more. We then discuss advanced concepts in robotics and how to program using ROS. You'll get a deep overview of the ROS framework, which will give you a clear idea of how ROS really works. During the course of the book, you will learn how to build models of complex robots, and simulate and interface the robot using the ROS MoveIt motion planning library and ROS navigation stacks. We'll go through great projects such as building a self-driving car, an autonomous mobile robot, and image recognition using deep learning and ROS. You can find beginner, intermediate, and expert ROS robotics applications inside! It includes content from the following Packt products: ? Effective Robotics Programming with ROS - Third Edition ? Mastering ROS for Robotics Programming ? ROS Robotics Projects
Table of Contents (37 chapters)
Title page
Copyright and Credits
Packt Upsell
Preface
Bibliography
Index

Designing and selecting the motors and wheels for the robot


The robot we are going to design should have a differential drive configuration, and from the preceding specification, we can first determine the motor torque values. From the payload value and robot body weight, we can easily compute the motor torque.

Computing motor torque

Let's calculate the torque required to move this robot.

The number of wheels is four, including two caster wheels. The number of wheels undergoing actuation is only two. We can assume the coefficient of friction is 0.6 and of wheel radius is 4.5 cm. We can use the following formula:

Total weight of robot = Weight of robot + Payload

Weight of the robot: 3 x 9.8 ≈ 30 N (W = mg)

Payload: 2 x 9.8 ≈ 20 N

Total weight: 30 + 20 = 50 N

This total weight should be split among the four wheels of the robot, so we can write it as W = 2 x N1 + 2 x N2, where N1 is the weight acting on each robot wheel and N2 is the weight acting on each caster wheels. The configuration of wheels...