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

Binary Codes

• bit is just called as binary digit
• To represent 2n elements, n bits are needed

Here are the following Binary Codes,

For example, the BCD code is otherwise called as 8421 code where the 8,4,2,1 are the weights assigned to the digits

for number 3 (0011), the weightage will be 0 * 8 + 0 * 4 + 1 * 2 + 1 *1

in 84-2-1 code, the weights are arranged like this,

for example, for number 2 (0110),  it is 0 * 8 + 1 * 4 + 1 * –2 + 0 * –1

similarly the same case for 2421 codes.

Excess – 3 is a code which is in excess of 3 in decimal numbers .

Error Detection Codes

• Binary information is usually transmitted from one place to other through wired medium, due to the electromagnetic radiation or external noise, the information bits can be changed (ie 1 to 0 or 0 to 1), in this scenario, there is a provision to check whether the given word or byte is correct or not. Parity bits are used for that.
• Odd parity or even parity is adopted based on the application, but mostly even parity is adopted.
• Parity bit is an extra bit added along with the given byte to make the number of 1’s in the total word is even or odd (based on even or odd parity)
 Message odd parity bit Message Even parity bit 0000 1 0000 0 0001 0 0001 1 0010 0 0010 1 0011 0 0011 0 0100 0 0100 1 0101 1 0101 0 0110 1 0110 0 0111 0 0111 1 1000 1 1000 1 1001 1 1001 0 1010 1 1010 0 1011 0 1011 1 1100 1 1100 0 1101 0 1101 1 1110 0 1110 1 1111 1 1111 0

Gray Code

Gray code is different from binary code in which only one bit change is there in the code group. Moving from one number to another number, there is just only one bit change. here is an example of Gray Code

 Gray Code Decimal Equivalent 0000 0 0001 1 0011 2 0010 3 0110 4 0111 5 0101 6 0100 7 1100 8 1101 9 1111 10 1110 11 1010 12 1011 13 1001 14 1000 15

Other Alpha Numeric Codes

• ASCII (American Standard Code for Information Interchange)
• used in Keywords,
• take 7 bit data
• can able to address 128 characters

• EBCIC  (Extended Binary Coded Decimal Interchange Code)
• This code is from IBM
• uses 8 bits, so addresses up to 256

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&#