Merge branch 'abescat-patch-1'

Article_Scientifique/main.tex

@@ -206,19 +206,157 @@ Third, the security of the wireless communication interface is investigated, wit
 vulnerabilities. A Flipper Zero device is used as a diagnostic tool to evaluate potential attack surfaces and identify 
 weaknesses in the communication layer.
 
-Finally, a dynamic model of the bicycle–cargo system is developed to improve rider experience. 
+Finally, a dynamic model of the bicycle-cargo system is developed to improve rider experience. 
 The objective is to minimize the perceived additional effort when towing a cargo cart. This is achieved through a 
-PID-based (Proportional–Integral–Derivative) control strategy combined with distance sensing, allowing adaptive 
+PID-based (Proportional-Integral-Derivative) control strategy combined with distance sensing, allowing adaptive 
 assistance based on system dynamics.
 
-% ***************************** Hardware-Based Six-Step Commutation Controller  ****************************************
+% ************************************** LOW TECH SIX STEP CONTROL ***************************************************** 
 
 \section{Hardware-Based Six-Step Commutation Controller}
 
-% ***************************** STM32-Based Field-Oriented Control Motor Drive *****************************************
+% ************************************** FIELD ORIENTED CONTROL ***************************************************** 
 
 \section{STM32-Based Field-Oriented Control Motor Drive}
+\label{sec:foc}
 
+This section presents the design and implementation of a high-performance 
+motor controller based on Field-Oriented Control (FOC).
+
+\subsection{Choice of FOC Over Trapezoidal Commutation}
+
+Table~\ref{tab:foc_vs_trap} summarizes the key differences between the 
+two commutation strategies, based on the literature reviewed in 
+Section~\ref{sec:related}.
+
+\begin{table}[htbp]
+\caption{Comparison between FOC and trapezoidal (six-step) commutation}
+\label{tab:foc_vs_trap}
+\centering
+\begin{tabular}{lcc}
+\toprule
+\textbf{Criterion} & \textbf{FOC} & \textbf{Six-Step} \\
+\midrule
+Torque ripple (at 500 rpm) & \SI{18.4}{\percent} & \SI{35.7}{\percent} \\
+Low-load efficiency & High & Moderate \\
+High-speed switching loss & Higher & Lower \\
+Position sensor requirement & Encoder (high resolution) & Hall sensors \\
+Implementation complexity & High & Low \\
+Hardware cost & Higher & Lower \\
+Dynamic response & Fast & Standard \\
+\bottomrule
+\end{tabular}
+\end{table}
+
+For our cargo bike application, rider comfort and smooth torque delivery 
+are priorities. FOC was therefore selected for the high-performance 
+controller, while a separate low-tech six-step board (Section~\ref{sec:sixstep}) 
+was developed for repairability.
+
+\subsection{Base Design: Cheap FOCer-2 Project}
+
+The starting point was the open-source \textit{Cheap FOCer-2} project, 
+which provides a complete KiCad design for a VESC-compatible board based 
+on an STM32F405 microcontroller. This design includes:
+\begin{itemize}
+    \item A three-phase MOSFET full-bridge power stage.
+    \item Gate drivers with built-in dead-time insertion.
+    \item Shunt resistors for phase current sensing.
+    \item USB and CAN interfaces.
+    \item An expansion header for encoder or Hall sensors.
+\end{itemize}
+
+The existing KiCad schematic and layout were used as the baseline for 
+our adaptations.
+
+\subsection{Integration of the Rocacher FOC Tile}
+
+Mr. Rocacher provided the Kicad schematic of a ready-to-use FOC tile based on an STM32L476 
+microcontroller.
+
+The initial idea was to make this tile \textit{pluggable} into our 
+carrier board, similar to an Arduino shield. This would allow :
+\begin{itemize}
+    \item Easy replacement of the computing core without re-soldering.
+    \item Modular upgrades of the microcontroller.
+    \item Simplified repair and maintenance.
+\end{itemize}
+
+However, the Cheap FOCer-2 project was not designed for such modularity. 
+Its routing is dense and highly optimized for a single, non-removable 
+F405 chip. Adapting it to accept an L476 tile while preserving all 
+critical functions (PWM, current sensing, USB communication) proved 
+challenging.
+
+\subsection{Pin Compatibility Verification: L476 vs F405}
+
+Before modifying the PCB, a thorough pin compatibility check was 
+performed between the STM32L476 and the STM32F405 
+(original Cheap FOCer-2 design). The following aspects were examined:
+\begin{itemize}
+    \item Physical pinout in LQFP64 package.
+    \item Alternate functions for PWM timers.
+    \item USB DP/DM pins (PA11/PA12).
+    \item Analog inputs for current sensing.
+    \item UART for BLE communication.
+\end{itemize}
+
+Three pin conflicts were identified and resolved as follows.
+
+First, the SPI\_MISO function on PA6 for the STM32F405 conflicts with a 
+DAC output on the same pin for the STM32L476 tile. Since this pin is 
+used for current sensing via SPI in the original Cheap FOCer-2 design, 
+the SPI communication was remapped to PA5 on the L476, which provides a 
+compatible alternate function.
+
+Second, the gate driver enable signal (EN\_GATE) was originally assigned 
+to PB5 on the F405. This pin is not accessible on the L476 
+tile. The signal was therefore moved to PC5, which is available and 
+can be configured as a standard GPIO output.
+
+Third, Hall sensor C was originally connected to PC8 (TIM8) on the F405. 
+This pin is not available on the L476 tile. The Hall sensor input was 
+therefore reassigned to PB3, configured as TIM2\_CH2, which provides 
+the necessary input capture functionality for Hall signal decoding.
+
+All other critical functions (PWM timers, complementary PWM, enable 
+signals, encoder inputs, UART, USB, and CAN) remain fully compatible 
+between the two microcontrollers. The ADC channel differences between 
+the F405 (ADC123/ADC12) and the L476 (ADC3) must still be handled in 
+firmware, as noted previously.
+
+\subsection{Schematic Design and KiCad Implementation}
+
+The original Cheap FOCer-2 schematic was modified in KiCad to replace the 
+integrated F405 with connectors for the L476 tile. The main modifications 
+included:
+\begin{itemize}
+    \item Removal of the F405 and its associated passive components.
+    \item Addition of two 20-pin headers to receive the Rocacher tile.
+    \item Re-routing of PWM, ADC, and USB signals to the headers.
+\end{itemize}
+
+The schematic passed Electrical Rule Check (ERC) with no errors. 
+
+\subsection{Routing Challenges and Current Status}
+
+The PCB layout was then started. The original Cheap FOCer-2 routing is 
+very dense. Inserting connectors for the removable tile while maintaining signal integrity proved 
+difficult.
+
+The main issues encountered were:
+\begin{itemize}
+    \item Some footprints for the tile connectors did not appear correctly 
+    in the layout after schematic import.
+    \item Routing of high-current paths (battery, motor phases) around the 
+    connectors required additional vias, increasing resistance.
+    \item Decoupling capacitors had to be repositioned, raising concerns 
+    about switching noise.
+\end{itemize}
+
+Currently, the schematic is validated, and the layout is under 
+development. Once routing is completed, the board will be manufactured 
+and tested with the VESC firmware adapted to the L476 tile.
 
 % ************************************** SOFTWARE AND CONNECTIVITY ***************************************************** 
 
@@ -304,7 +442,7 @@ for the the MAD associates.
 % ************************************ DYNAMIC MODELLING ***************************************************************
 
 
-\section{Dynamic Modelling and Control of the Bicycle–Cargo System}
+\section{Dynamic Modelling and Control of the Bicycle-Cargo System}
 
 \subsection{Dynamic System Modelling} 
 
@@ -376,7 +514,7 @@ where $e_{\text{ref}} = \SI{-0.5}{\meter}$ represents the desired equilibrium of
 
     \centering 
     \includegraphics[width=\linewidth]{./Figures/sys_dyn_matlab.png} 
-    \caption{Closed-loop model of the bicycle–cargo system with PI control.} 
+    \caption{Closed-loop model of the bicycle-cargo system with PI control.} 
     \label{fig:simulink-closedloop} 
 
 \end{figure} 
@@ -443,6 +581,33 @@ However, due to the absence of direct velocity measurements during the experimen
 be extracted from these tests. Consequently, a precise estimation of dynamic friction parameters and energy efficiency 
 could not be achieved.
 
+\subsection{FOC Controller Validation}
+
+\subsubsection{Current Status Summary}
+
+Table~\ref{tab:foc_status} summarizes the current status of the FOC 
+controller development.
+
+\begin{table}[htbp]
+\caption{FOC controller development status}
+\label{tab:foc_status}
+\centering
+\begin{tabular}{l c}
+\toprule
+\textbf{Task} & \textbf{Status} \\
+\midrule
+VESC firmware compilation & Completed \\
+Pin compatibility (F405 / L476) & Completed \\
+Schematic design (KiCad) & Completed \\
+ERC validation & Completed \\
+PCB routing & In progress \\
+Tile footprint correction & In progress \\
+Board manufacturing & Planned \\
+Hardware testing & Planned \\
+\bottomrule
+\end{tabular}
+\end{table}
+
 
 % ******************************** DISCUSSION **************************************************************************
 
@@ -476,6 +641,19 @@ What should be a clear conclusion from our test with the jammer is that a contro
 avoided when possible and practical. Examples where this could be relevant include electric skateboards, as cables could 
 impose a tripping hazard. There, an encapsulation of an encrypted control frame could be an thought. 
 
+% ******************************** Perspectives and Future Work ************************************************************
+
+\section{Perspectives and Future Work}
+
+Based on the results obtained and the limitations identified during this 
+project, several directions for future work are proposed.
+
+\subsection{Hardware Completion and Testing}
+The VESC-based FOC PCB requires routing completion and prototype 
+manufacturing. Once fabricated, the board must be tested under real 
+operating conditions (varying loads, road profiles, and battery voltage).
+
+% ******************************** CONCLUSION **************************************************************************
 
 \section{Conclusion/Summary}
 
@@ -495,8 +673,29 @@ impose a tripping hazard. There, an encapsulation of an encrypted control frame
 %quantities and units. For example, write ``Temperature (K)'', not 
 %``Temperature/K''.
 
+% ******************************** REMERCIEMENTS **************************************************************************
+
 \section*{Acknowledgment}
 
+The authors would like to thank Pascal Acco and Thierry Rocacher for their 
+continuous technical guidance and support throughout this project. Their 
+expertise in power electronics, embedded systems, and PCB design was 
+invaluable.
+
+We also thank La Manufacture Autonome Décentralisée (LaMAD) for providing 
+the use case, the technical requirements, and the cargo bike platform used 
+for validation.
+
+Finally, we acknowledge the INSA Toulouse GEI department for providing 
+access to laboratory facilities, measurement equipment, and the necessary 
+components for prototyping.
+
+This work was carried out as part of the 4th-year research project (PIR) 
+at INSA Toulouse.
+
+% ******************************** IA **************************************************************************
+\section*{Statement on AI Usage}
+
 The authors acknowledge the use of generative AI tools during this project, both for the development work and for 
 writing this paper.