\chapter{Introduction}

\section{Motivation}

\subsection{Transportation of Bulk Material}

It is necessary in several industries, including those of mining and manufacturing, to transport bulk material from one on-site location to another. In mining, it may be sand or gravel. In manufacturing, it may be powdered chemicals.

The transportation of this bulk material typically involves the use of a belt conveyor. These belt conveyors are designed especially with the purpose of containing bulk material, as well as applying the necessary forces to transport them.

\subsection{Measuring Bulk Material Flow}

\begin{wrapfigure}[10]{R}{0.4\textwidth}
	\centering
    \includegraphics[width=0.4\textwidth]{beltscale}
    \caption{A conventional electronic belt scale. Source: \url{https://www.mts-waagen.de/}}
\end{wrapfigure}

This transportation of bulk material flow introduces challenges into the processing engineering and automation ability of the facility.  This work deals with the specific challenge of measuring bulk material flow on a conveyor.

Possessing this information is important for the proper control and regulation of the conveyor system, as well as for safety functions. Knowing when a belt is overloaded, running empty, or broken may prevent damage to people and machinery.

\subsection{Conventional Belt Scales}

The conventional method of measuring bulk material flow in use in the industry today the electronic belt scale. These scales use load cells to translate compression and tension into electrical signals. These signals representing weight may be then be converted into measurements of volume.

These electronic belt scales are robust and proven in the field. However, there are also downsides with this approach.

Firstly, the retrofitting of these belt scales are difficult and costly. \todo{add more info}

Secondly, the cost of the units themselves are high, not including the necessary maintenance and servicing these units require. \todo{add cost examples}

Other specialized methods for measuring material flow, such as using a radiation based sensor, are not considered here, as they require highly-skilled personnel to design, develop, deploy and maintain.

\section{Aims of this Work}

\subsection{Research Question}
The central research question that is investigated in this work is the following:

\textit{How can a cheaper and easier to install measurement system for bulk material flow on a conveyor belt be designed?}

\subsection{Use of Commercially-Available Products}

As given by the research question above, one of the central requirements of the research question is a question of cost.

In order to reduce the costs of development, as well as to keep unit cost price low, this work strives to use commercially available products wherever suitable.

\subsection{Use of the LIDAR Sensor}

The usage of the LIDAR sensor was implemented in order to fulfill the second requirement of the research question, namely that the solution must be easier to install, than other conventional solutions.

As is discussed in the following section on design, the LIDAR sensor was selected primarily because it is a contact-less sensor. This means that installation can be carried out with little to no adjustments to the existing conveyor belt system. The LIDAR sensor must simply be suitably positioned in order to gather and deliver data.

\subsection{Requirements \& Restrictions}

Besides fulfilling the research question, the design solution should ideally fulfill the following restrictions and requirements as well.

\begin{itemize}
\item \textbf{Industrial Robustness} - The final product should be able to withstand the harsh environments that it would likely be installed in, i.e. in a gravel pit. This means the product must be adequately housed and protected from the environment, against vibrations and shocks.
\item \textbf{Industrial Connectivity} - The product should be able to interface with existing industrial networks, i.e. using Industrial Ethernet.
\item \textbf{Real-Time Ability} - The product should ideally deliver values in Real-Time through the required interface. This means not only a high enough data resolution, but also a high determinism.
\end{itemize}

Although not strictly necessary, a significant benefit would be:
\begin{itemize}
\item \textbf{Remote Control} - The product should be able to be configure and diagnosed remotely, in order to prioritize simplicity of installation and maintenance.
\end{itemize}

\subsection{Conception of the Design}

Analysis of the research question as well as the other requirements have led us to use the following components to build the final product.
\begin{itemize}
\item \textbf{Raspberry Pi 4B} - Provides a low-cost platform with a Linux kernel and OS for processing data
\item \textbf{netHAT} - A HAT format extension module for the Raspberry Pi that provides Industrial Ethernet capabilities
\item \textbf{Intel RealSense L515 LIDAR Sensor} - Commercially available LIDAR sensor unit, compatible with the Pi
\end{itemize}


\section{Approach}
The following lays out an overview of the steps taken in order to realize the final product of this project. For more details on the specifics of the steps, please see \autoref{chap:design}.

\subsection{Interfacing with the LIDAR sensor}
The initial step of this project was naturally to establish an interface with the sensor itself. This includes:
\begin{itemize}
\item Preparing the development environment
\item Building the necessary libraries and drivers
\item Writing basic test software to manipulate sensor data
\end{itemize}

\subsection{Proof-of-Concept Software}
After being able to successfully interface with the sensor, a proof-of-concept software was designed and written. Later, a GUI interface was also added the software to improve ease-of-use. The software was designed to be able to do the following things:
\begin{itemize}
\item Remotely acquire the raw sensor data over the network
\item Display the raw sensor data in a meaningful way
\item Display, calibrate and use the sensor data as a line scanner, with \textbf{instantaneous cross-sectional area} as an output
\end{itemize}

\subsection{Laboratory Prototype}
Once the proof-of-concept software was stable, the setup was moved into a laboratory environment in order to further develop the main functionalities of the prototype. Among the functionalities that were developed:
\begin{itemize}
\item Image preparation (offset, rotation, skew)
\item Cross-Correlation methods to determine band speed
\item Profinet interface to deliver processed data
\end{itemize}

\subsection{Field Testing and Refinement}
Eventually a staged was reached where development on the prototype in a small-scale laboratory setting was no longer adequate. Development and testing was then continued on-site at a gravel pit in order to validate laboratory results and further refine the software.