### Simulation of URDF, Gazebo and Rviz | ROS Noetic Tutorial 8

Design a User-defined robot of your choice (or you can use the URDF file) and enable the LIDAR Scanner so that any obstacle placed on the path of the light scan will cut the light rays. Visualize the robot in the Gazebo workspace, and also show the demonstration in RViz.   (NB: Gain knowledge on wiring URDF file and .launch file for enabling any user-defined robot to get launched in the gazebo platform.) SLAM : One of the most popular applications of ROS is SLAM(Simultaneous Localization and Mapping). The objective of the SLAM in mobile robotics is to construct and update the map of an unexplored environment with the help of the available sensors attached to the robot which will be used for exploring. URDF: Unified Robotics Description Format, URDF, is an XML specification used in academia and industry to model multibody systems such as robotic manipulator arms for manufacturing assembly lines and animatronic robots for amusement parks. URDF is especially popular with users of the Robo

### Number Conversion

Number conversion is the fundamental operation of any digital systems.

There are different bases like base2, base8, base10 and base 16

 Base – 10 Base 2 (Binary) Base 8 (Octal) Base 16 (Hexadecimal) 0 0000 00 0 1 0001 01 1 2 0010 02 2 3 0011 03 3 4 0100 04 4 5 0101 05 5 6 0110 06 6 7 0111 07 7 8 1000 10 8 9 1001 11 9 10 1010 12 A 11 1011 13 B 12 1100 14 C 13 1101 15 D 14 1110 16 E 15 1111 17 F

The above table shows the various base systems.

Converting between one base to another base is of importance.  Usually all the numbering systems of day to day life is done using Base 10 or Decimal system. So it is necessary to convert

• Other Base to Decimal
• Decimal to other base

Any number represented as

 anan-1an-2an-3…..a1a0 . a-1a-2……..a-n

We will see one by one

Decimal to Binary (Base 10 to Base 2)

(19.456)10 – (?.?)2

In the above, the number 19.456 has to be converted to binary or base2 which will have only 0s and 1s.

First we will take 19

 Division Quotient Remainder Remarks 19/2 9 1 a0=1 9/2 4 1 a1=1 4/2 2 0 a2=0 2/2 1 0 a3=0 1/2 0 1 a4=1

so the conversion is 10011

Secondly we will take (0.456)10

 Multiplication Whole number decimal Remarks 0.456 * 2 0 0.912 a-1=0 0.912 * 2 1 0.824 a-2=1 0.824 * 2 1 0.648 a-3=1 0.648 * 2 1 0.296 a-4=1

Therefore (0.456)10 is (0.0111)2

Finally (19.456)10 = (10011.0111)2

Binary (Base 2) to Decimal (Base 10) Conversion

(11110.0111)2 = (?.?)10

Let us take the whole portion 11110

 1 1 1 1 0 . 0 1 1 1 a4 a3 a2 a1 a0 . a-1 a-2 a-3 a-4 1 * 24 1 * 23 1 * 22 1 * 21 0 * 20 . 0 * 2-1 1 * 2-2 1 * 2-3 1 * 2-4 16 8 4 2 0 . 0.5 0.25 0.125 0.0625

Total is 30.9375

Decimal to Octal (Base 10 to Base 8)

(19.456)10 – (?.?)8

In the above, the number 19.456 has to be converted to binary or base2 which will have only 0s and 1s.

First we will take 19

 Division Quotient Remainder Remarks 19/8 2 3 a0=3 2/8 0 2 a1=2

so the conversion is 23

Secondly we will take (0.456)10

 Multiplication Whole number decimal Remarks 0.456 * 8 3 0.648 a-1=3 0.648 * 8 5 0.184 a-2=5 0.824 * 8 1 0.472 a-3=1

Therefore (0.456)10 is (0.351)8

Finally (19.456)10 = (23.351)8

Octal (Base 8) to Decimal (Base 10) Conversion

(337.64)8 = (?.?)10

Let us take the whole portion 11110

 3 3 7 . 6 4 a2 a1 a0 . a-1 a-2 3 * 82 3 * 81 7 * 80 . 6 * 8-1 4 * 8-2 192 24 7 . 0.75 0.0625

Total is 267.8125

Decimal to Hexadecimal (Base 10 to Base 16)

(19.456)10 – (?.?)16

In the above, the number 19.456 has to be converted to binary or base2 which will have only 0s and 1s.

First we will take 19

 Division Quotient Remainder Remarks 19/16 1 3 a0=3 1/16 0 1 a1=1

so the conversion is (13)16

Secondly we will take (0.456)10

 Multiplication Whole number decimal Remarks 0.456 * 16 7 0.296 a-1=7 0.296 * 16 4 0.736 a-2=4 0.736 * 16 B 0.776 a-3=B

Therefore (0.456)10 is (0.74B)16

Finally (19.456)10 = (13.74B)16

Octal (Base 8) to Decimal (Base 10) Conversion

(1AB.62)16 = (?.?)10

Let us take the whole portion 11110

 1 A B . 6 2 a2 a1 a0 . a-1 a-2 1 * 162 10 * 161 11 * 160 . 6 * 16-1 2 * 16-2 256 160 11 . 0.375 0.007

Total is (427.382)10

### Installing ns3 in Ubuntu 22.04 | Complete Instructions

In this post, we are going to see how to install ns-3.36.1 in Ubuntu 22.04. You can follow the video for complete details Tools used in this simulation: NS3 version ns-3.36.1  OS Used: Ubuntu 22.04 LTS Installation of NS3 (ns-3.36.1) There are some changes in the ns3 installation procedure and the dependencies. So open a terminal and issue the following commands Step 1:  Prerequisites \$ sudo apt update In the following packages, all the required dependencies are taken care and you can install all these packages for the complete use of ns3. \$ sudo apt install g++ python3 python3-dev pkg-config sqlite3 cmake python3-setuptools git qtbase5-dev qtchooser qt5-qmake qtbase5-dev-tools gir1.2-goocanvas-2.0 python3-gi python3-gi-cairo python3-pygraphviz gir1.2-gtk-3.0 ipython3 openmpi-bin openmpi-common openmpi-doc libopenmpi-dev autoconf cvs bzr unrar gsl-bin libgsl-dev libgslcblas0 wireshark tcpdump sqlite sqlite3 libsqlite3-dev  libxml2 libxml2-dev libc6-dev libc6-dev-i386 libclang-dev llvm-

### Installation of NS2 (ns-2.35) in Ubuntu 20.04

Installation of NS2 (ns-2.35) in Ubuntu 20.04 LTS Step 1: Install the basic libraries like      \$] sudo apt install build-essential autoconf automake libxmu-dev Step 2: install gcc-4.8 and g++-4.8 open the file using sudo mode \$] sudo nano /etc/apt/sources.list Include the following line deb http://in.archive.ubuntu.com/ubuntu bionic main universe \$] sudo apt update \$] sudo apt install gcc-4.8 g++-4.8 Step 3:  Unzip the ns2 packages to home folder \$] tar zxvf ns-allinone-2.35.tar.gz \$] cd ns-allinone-2.35/ns-2.35 Modify the following make files. ~ns-2.35/Makefile.in Change @CC@ to gcc-4.8 change @CXX@ to g++-4.8 ~nam-1.15/Makefile.in ~xgraph-12.2/Makefile.in ~otcl-1.14/Makefile.in Change in all places  @CC@ to gcc-4.8 @CPP@ or @CXX@ to g++-4.8 open the file: ~ns-2.35/linkstate/ls.h Change at the Line no 137  void eraseAll() { erase(baseMap::begin(), baseMap::end()); } to This void eraseAll() { this->erase(baseMap::begin(), baseMap::end()); } All changes made Step 4: Open a new termi

### Installation of NS2 in Ubuntu 22.04 | NS2 Tutorial 2

NS-2.35 installation in Ubuntu 22.04 This post shows how to install ns-2.35 in Ubuntu 22.04 Operating System Since ns-2.35 is too old, it needs the following packages gcc-4.8 g++-4.8 gawk and some more libraries Follow the video for more instructions So, here are the steps to install this software: To download and extract the ns2 software Download the software from the following link http://sourceforge.net/projects/nsnam/files/allinone/ns-allinone-2.35/ns-allinone-2.35.tar.gz/download Extract it to home folder and in my case its /home/pradeepkumar (I recommend to install it under your home folder) \$ tar zxvf ns-allinone-2.35.tar.gz or Right click over the file and click extract here and select the home folder. \$ sudo apt update \$ sudo apt install build-essential autoconf automake libxmu-dev gawk To install gcc-4.8 and g++-4.8 \$ sudo gedit /etc/apt/sources.list make an entry in the above file deb http://in.archive.ubuntu.com/ubuntu/ bionic main universe \$ sudo apt update Since, it&#