@@ -75,7 +80,7 @@ A few useful hints, commands, web addresses, and file paths:
\begin{center}
\begin{tabular}{ll}
\large{\texttt{git checkout .}}
& Removes all changes
& Removes all changes (note the dot)
\\
\large{\texttt{git checkout master}}
& Switches to the ``master" branch
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@@ -92,7 +97,7 @@ A few useful hints, commands, web addresses, and file paths:
\large{\texttt{\roslaunchcommand}}
\end{center}
This will launch the Graphical User Interface (GUI) that is explained on the wiki and allows you to test out the flight performance of your control algorithm on the quad-rotor. This command works because \texttt{d\_fall\_pps} is defined as the absolute path to where the \texttt{Agent.launch} file is located.
This will launch the Graphical User Interface (GUI) that is explained on the wiki and allows you to test out the flight performance of your control algorithm on the quad-rotor. This command works because \texttt{\rospackagename} is defined as the absolute path to where the \texttt{\launchfilename} file is located.
\end{enumerate}
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@@ -104,9 +109,7 @@ A few useful hints, commands, web addresses, and file paths:
\item Kill the GUI process, (this is achieved by pressing the \texttt{Ctrl+c} in the terminal window from which \texttt{\roslaunchcommand} was run),
\item Re-compile all of the code. To do this, in a Terminal window first change to the \texttt{pps\_ws} folder of the repository (where \texttt{ws} stands for workspace), and then use the \texttt{catkin\_make} command, i.e.:
\texttt{catkin\_make}
\item Re-compile all of the code. To do this, in a Terminal window first change to the \texttt{\workspacefoldername} folder of the repository (where \texttt{ws} stands for workspace), and then use the \texttt{catkin\_make} command, i.e.:
\begin{center}
\begin{tabular}{ll}
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@@ -118,7 +121,7 @@ A few useful hints, commands, web addresses, and file paths:
\end{tabular}
\end{center}
This will compile all the code, or throw an error if your changes have introduced errors that prevent the compilation from completing successfully.
This will compile all the code, or throw an error if the compilation is unsuccessfully.
\item Relaunch the GUI, (by running \texttt{\roslaunchcommand} from a Terminal window).
\end{enumerate}
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@@ -126,11 +129,11 @@ A few useful hints, commands, web addresses, and file paths:
\vspace{0.3cm}
\noindent
Steps~\textbf{(1)} and \textbf{(2)} are required because the GUI and your controller is loaded into RAM when the system is launched, and so your newly compile changes in Step~\textbf{(3)} only take effect when the system is launched again in Step~\textbf{(4)}.
Steps~\textbf{(1)} and \textbf{(2)} are required because the GUI and your controller is loaded into RAM when the system is launched, and so your newly compiled changes in Step~\textbf{(3)} only take effect when the system is launched again in Step~\textbf{(4)}.
\vspace{0.3cm}
\noindent
Note also that the GUI will launch in Step~\textbf{(4)} even if there were compiler errors in Step~\textbf{(3)}, but it is launching the previously compiled version and hence any changes you made will not be running.
Note also that the GUI will launch in Step~\textbf{(4)} even if there were compiler errors in Step~\textbf{(3)}, but it is launching the previously compiled version and hence any changes you made will \textbf{not} be running.
\item Your controller is implemented using the following 3 files:
\begin{center}
\begin{tabular}{l}
\large{\texttt{\cppfile}}
\\
\large{\texttt{\headerfile}}
\\
\large{\texttt{\yamlfile}}
\end{tabular}
\end{center}
The \texttt{.cpp} file is where you implement your controller. The \texttt{.h} file is where you can define new variables and function (these can also be added at the top of the \texttt{.cpp} file). The \texttt{.yaml} file is where you add parameters that can be changed during flight.
\item In the \texttt{\cppfile}, locate the function named:
\begin{center}
\texttt{\computecontroloutputfunction}
\end{center}
This is the function where you implement your controller. When your controller is running, this function is called at the frequency of the motion capture system, normally set to 200Hz. Every time your function is called, it is provided with the most recent position and attitude measurement, and is expected to return the control action to be sent to your Crazyflie.
\item The position and yaw error are already computed in the first lines of the \texttt{\computecontroloutputfunction} function. You should check whether the error is computed as ``setpoint minus measurement" or the opposite.
\item A function for rotating the inertial frame position errors into body frame errors is already defined and named:
\begin{center}
\texttt{\convertintobodyframefunction}
\end{center}
however the conversion is not implemented. You should edit this function to implement the conversion from inertial frame into body frame.
\item A function for converting a thrust in Newtons to a 16-bit command is already defined and named:
\begin{center}
\texttt{\convertnewtonsintocommandfunction}
\end{center}
The conversion is correctly implemented, however, if the result is greater than ${(2^{16}\!-\!1)}$, then this is wrapped back around when the command is received by the Crazyflie. You should edit this function to limit commands to a maximum of \texttt{60000}, and set commands below \texttt{2000} to be \texttt{0}.
\end{enumerate}
\clearpage
\begin{center}
\textbf{The following steps expliain how to add a \texttt{yaml} parameter}
This defines a class variable named \texttt{yaml\_example\_parameter} which is where the value from the \texttt{.yaml} file will be stored when it is loaded.
\textbf{Note:} the variable can be given any name, we use the convention of a \texttt{yaml\_} prefix for variables that store values loaded from a yaml file.
\textbf{Note:} it is important to the initialise the variable with an appropriate value, in this case \texttt{1.0}. This is because the variable \texttt{yaml\_example\_parameter} may be used during execution of your code before it is loaded for the first time, and so the default initialisation value of zero will be problematic if you divide by this variable anywhere.
\item The loading of values from the \texttt{.yaml} file is performed in the \texttt{.cpp} file. Hence locate in the file \texttt{\cppfile} the function named:
The function \texttt{getParameterFloat} that is called by this line searches the appropriate \texttt{.yaml} file for the string \texttt{"example\_parameter"} and returns the respective value found in the \texttt{.yaml} file. Other functions available for loading different types of parameters are:
\begin{center}
\begin{tabular}{l}
\large{\texttt{getParameterInt}}
\\
\large{\texttt{getParameterBool}}
\\
\large{\texttt{getParameterFloatVector}}
\end{tabular}
\end{center}
The syntax for the first two functions is identical to \texttt{getParameterFloat}, while the syntax for the third function differs slightly and an example can be found in the \texttt{.cpp} file.
