From 4e66f84cb10a58a5a2d6a88f001d028ec09c3d19 Mon Sep 17 00:00:00 2001 From: Leandro Ebner Date: Sun, 16 Jun 2024 06:30:52 +0200 Subject: [PATCH] updated sr, looks good --- contents/safety-report.tex | 29 +++++++---------------------- 1 file changed, 7 insertions(+), 22 deletions(-) diff --git a/contents/safety-report.tex b/contents/safety-report.tex index 4005d78..dbdd540 100644 --- a/contents/safety-report.tex +++ b/contents/safety-report.tex @@ -7,7 +7,7 @@ \section{License} \begin{figure}[h!] \includegraphics{contents/figures/gfdl-logo.png} \end{figure} - + \section{Introduction} This document will serve as a comprehensive guide through the entire power distribution and wiring system of our rover. It meticulously details all relevant safety measures designed to minimize the likelihood of hazards or environmental damage. By following these guidelines, we aim to ensure that our work adheres to the highest safety standards. @@ -16,51 +16,36 @@ \section{Introduction} In addition to outlining essential safety protocols, this guide sets forth the minimum standards for both material and personal safety. These standards apply not only during the construction phase but also throughout the actual operation of all electronic components. To enhance understanding and clarity, we have included several schematics, data sheets, and detailed calculations. These resources are designed to provide a thorough illustration of the rover's internal architecture and functionality, making the document as informative and accessible as possible. - - \begin{table}[b] \centering \begin{tabular}{|c|c|c|c|} \hline Revision& Date submitted& Summary of changes &Authored\\ \hline - v1.0.0& 16.06.2024& Inital release &Leandro Ebner\\ \hline + v1.0.0& 16.06.2024& Initial release &Leandro Ebner\\ \hline \end{tabular} \end{table} \clearpage \section{Hazardous Material List} -Our rover contains - -Dino-bot's power architecture consists of an energy storage module, an emergency stop system, a main -power distribution system, a secondary power distribution and several -downstream devices. - - -The legend for the rover systems architecture, and the detailed circuit diagrams is -shown below. -The rover uses 5 standard voltages for the distribution. These are unregulated 22.2v -from the battery, a regulated 12v for linear actuators and Arduino Mega, a regulated 9v -four ip cameras, a regulated 6.5v for servo motors and regulated 5v for Rasperry Pi’s. \newpage - - \newpage \section{Power Architecture} - -The rover's power architecture is divided into two separate power systems. This approach ensures galvanic isolation between the power and logic components, which is necessary to eliminate any possible wiring configuration in which a so-called "ground loop" could form. The underlying problem is based on the fact that there exists an interface and thus an electrical connection between the individual components. While the communication between power and logic components is implemented by establishing a physical connection between their corresponding GPIO pins and reading different voltage levels, there must be a precise reference voltage available. Generally speaking, this is done by using a common ground. Hence, the most basic form to utilize that common ground connection is to form a "star ground." If there are multiple paths to ground, a "ground loop" is present. These ground loops, in combination with wire inductance, can cause issues for high-current electronics like our motor controllers (in this particular case we are utilizing ODrives). This is further illustrated in Figure XY. +The rover's power architecture is divided into two separate power systems. This approach ensures galvanic isolation between the power and logic components, which is necessary to eliminate any possible wiring configuration in which a so-called "ground loop" could form. The underlying problem is based on the fact that there exists an interface and thus an electrical connection between the individual components. While the communication between power and logic components is implemented by establishing a physical connection between their corresponding GPIO pins and reading different voltage levels, there must be a precise reference voltage available. Generally speaking, this is done by using a common ground. Hence, the most basic form to utilize that common ground connection is to form a "star ground." If there are multiple paths to ground, a "ground loop" is present. These ground loops, in combination with wire inductance, can cause issues for high-current electronics like our motor controllers (in this particular case we are utilizing ODrives). This is further illustrated in Figure \ref{ground_loop_bad}. \begin{figure}[h] \includegraphics[width=\textwidth]{contents/figures/ground_loop_bad.png} +\caption{Ground loop causes current flow $I_{Injected}$} +\label{ground_loop_bad} \end{figure} -The issue is the inductance of the power wires between the motor controllers and the battery. This inductance, coupled with the high current drawn by the motor controllers, causes $V_1$ to be different as $V_2$, leading to potential mismatch in the voltage levels. As the motor controllers demand substantial current, the wire inductance can generate significant voltage drops along the power lines. If the voltage caused by the wire inductance and current is high enough, the 0-5V GPIO signals can swing much higher or lower than the defined voltage range, potentially exceeding safe operational limits. These fluctuations in voltage can introduce erratic behavior in the control system, compromising the performance and reliability of the motor controllers. This causes a current to flow through the ODrives GPIO pins, which can lead to unintended electrical noise and potential damage to sensitive electronic components. To mitigate these effects, the following techniques were considered to maintain stable voltage levels within the desired range. +The issue is the inductance of the power wires between the motor controllers and the battery. This inductance, coupled with the high current drawn by the motor controllers, causes $V_1$ to be different as $V_2$, leading to potential mismatch in the voltage levels. As the motor controllers demand substantial current, the wire inductance can generate significant voltage drops along the power lines. If the voltage caused by the wire inductance and current is high enough, the 0-5V GPIO signals can swing much higher or lower than the defined voltage range, potentially exceeding safe operational limits. These fluctuations in voltage can introduce erratic behavior in the control system, compromising the performance and reliability of the motor controllers. This causes a current to flow through the ODrives GPIO pins, which can lead to unintended electrical noise and potential damage to sensitive electronic components. \subsection{Reducing length of high-current wires} -All wires have some amount of inductance, which is an inherent property of any conductor through which current flows. The inductance is proportional to the length of the wires and the area of the loop formed by the power wires, meaning longer wires and larger loops will have higher inductance. This inductance can create unwanted resistance to changes in current flow, leading to voltage drops and potential interference with the system's performance. It is beneficial to keep those wires as short as possible and as close together as possible. By doing so, the loop area is minimized, and the inductance is reduced, thereby mitigating the adverse effects. However, this reduces the effect of the problem but does not eliminate it entirely, as even minimal inductance can cause issues in high-frequency and high-current applications. +To mitigate these effects, it is substantial to keep the main powers as short as possible. All wires have some amount of inductance, which is an inherent property of any conductor through which current flows. The inductance is proportional to the length of the wires and the area of the loop formed by the power wires, meaning longer wires and larger loops will have higher inductance. This inductance can create unwanted resistance to changes in current flow, leading to voltage drops and potential interference with the system's performance. It is beneficial to keep those wires as short as possible and as close together as possible. By doing so, the loop area is minimized, and the inductance is reduced, thereby mitigating the adverse effects. However, this reduces the effect of the problem but does not eliminate it entirely, as even minimal inductance can cause issues in high-frequency and high-current applications. \subsection{Galvanic isolation}