The assignment is worth $20\%$ of the total mark for this module. In this assignment, you

are required to program a Turtlebot $3$ burger robot to move following a square path using

ROS$2$ and Python. Your code also needs to record the odometry data collected when

the robot moves. The recorded data should be used to evaluate your codes and the

parameters set in the code. Finally, you are required to submit a report which describes

your code and the experiment results.

The Task:

The task is to program and test a differential drive robot to trace out a square trajectory.

The square tracing robot should move along a square trajoctory with the length of $1$

meter. The robot should start from $(0,0)$ with a heading of $0$ degree, move forward $1$

meter and stop at $(1,0).$ Then it should turn $90$ degrees, move forward $1$ meter, and stop

at $(1,1).$ Next it should turn $90$ degrees, move forward $1$ meter, and stop at $(0,1).$ Finally,

it should turn $90$ degrees, move forward $1$ meter, and stop at $(0,0).$ You need to use mm

in the code. Then the distance will be $1000mm.$

You should use appropriate methods in ROS$2$ and its dependent packages to control

the robot to move. You also need to use appropriate methods in ROS$2$ and its dependent

packages to keep the track of the robot pose. When you collect the odometry data, only

four points at the corners are not enough to show the square trajectory. More data points

should be sampled.

The robot should be displayed in Rviz when the robot is moving and also its pose should

be recorded in a data file. After completing the square, you can use the data file to draw

a trajectory in Microsoft Excel or other tools. More than one trial with different speeds

are required.

The robot can be controlled by varying the translational and rotational velocities. This

is implemented by publishing $"/$cmd$\_$vel" topic with "Twist" message to the robot. You

need to find a way to control the robot to move towards $4$ comer goal positions and turn

$90$ degrees on the spot. This part of your code is called the position controller.

Your code can subscribe to $\%$odom" topic with "Odometry" message to obtain the

odometry data when the robot is moving. There are two parts in Odometry message:

pose and twist. We need to access the pose information, which includes position $(x,y,$

z$)$ and orientation in quatemion. For a ground $2$D robot, we need to use position $(x,y)$

and heading which can be computed from quaternion. Please see the example $8$ in the

lab notes for more information. This part of your code is called the odometry logger$.$

The Report:

The report should be in PDF and must include a cover page with the module name,

student name and registration ID$.$ The source code $($for the node you developed$)$ should

be made as a text file and submitted together with the report. The maximum length of

the report is of $10$ pages $($include the appendix$).$ The report should include:

$1.$ Description of your controller for moving forward $1$ meter $(20\%).$

You should explain how to move the robot forward for $1$ meter or to next goal

position. As the robot is controlled by varying its translational and rotation

velocities, it is not straight forward to implement this function. There are multiple

ways to implement this function. For example, you can use a PID controller to

adjust the translational velocity until the distance between the robot and goal

position is less than a predefined error. You need to show how the parameters used

in the PID controller affect the performance of your controller by using diagrams

of recorded odometry data. If you use an open loop controller, you will lose

significant part of the marks.

$2.$ Description of your controller for turning $90$ degrees $(20\%).$

You should explain how to turn the robot for $90$ degrees. As the robot is controlled

by varying its translational and rotation velocities, it is not straight forward to

implement this function. There are multiple ways to implement this function. For

example, you can use a PID controller to adjust the angular velocity until the angle

the robot turned is close to $90$ degrees. You need to show how the parameters used

in the PID controller affect the performance of your controller by using diagrams

of recorded odometry data. If you use an open loop controller $($like move $1$s with a

fixed velocity $1$m$/$s$),$ you will lose significant part of the marks.

$3.$ Explanation of your odometry logger $(20\%).$

The odometry logger can produce the pose information. In $2$D case, the pose

information is x$,$ y$,$ and heading. The odometry data in Turtlebot$3$ burger is obtained

by fusing the readings of encoders and IMU. You need to understand the

information obtained in Odometry message and have the ability to convert it into

$($x$,$ y$,$ and heading$).$

use a PID controller please