Unmanned Aerial System Hybrid Powertrain Testbed

As a key member and Quality Assurance Coordinator for the award-winning (ASME 2nd Place) "Unmanned Aerial Systems Hybrid Powertrain Testbed" senior design project, I was deeply immersed in the practical design, intricate instrumentation, and rigorous testing phases critical to its success. Our objective, in collaboration with Kickstage Consulting, was to develop a modular testbench to characterize the thermal behavior of PCB stators and rotors for hybrid drone powertrains. I spearheaded the development and execution of the project's core testing and instrumentation capabilities, taking a leading role in bridging the gap between theoretical design and functional hardware. This encompassed the entire hardware testing lifecycle, from initial conceptualization of the electronic and data acquisition systems to the execution of detailed experimental procedures that formed the backbone of our project's performance analysis and findings.

My initial contributions focused on the design aspects, where I designed the PCB stator templates using Altium Designer. These templates, including 2-layer, 1oz copper configurations with 30-turn and 20-turn variants, were foundational for our thermal characterization goals, allowing us to simulate heat generation and test different stator configurations. I also contributed to the CAD modeling for several aspects of the overall motor and testbed assembly, ensuring our physical design was modular and robust for evaluating PCB stators and rotors, aligning with our aim to create a versatile testing platform.

A significant portion of my effort was dedicated to developing the complete instrumentation and control software, which was crucial for operating the testbench and gathering reliable data. I single-handedly wrote all the Arduino Uno code for the precise speed control of the Turnigy SK3 Brushless DC (BLDC) motor via an Electronic Speed Controller (ESC). This involved reading analog input from a potentiometer, implementing data smoothing techniques to reduce signal jitter, and mapping these values to precise PWM (Pulse Width Modulation) signals (1000-2000 μs) for the ESC, including the necessary ESC arming sequence for safe startup. Concurrently, to capture crucial thermal data, I developed the firmware for an ESP32 microcontroller to interface with three K-type thermocouples via MAX6675 modules. This system was engineered to manage timestamped temperature readings from the center, middle, and edge of the PCB stator traces, apply calibration offsets (e.g., 16.25∘C), and log data every 0.5 seconds to the serial monitor, which we then captured using PuTTY for detailed analysis.

My role extended to leading and executing nearly all hardware testing procedures. This involved meticulous setup of the testbench, including the 80/20 aluminum frame, motor and bearing blocks, ensuring the critical 1mm air gap between rotor and stator, and the careful, strategic placement of the fine-wire thermocouples. I conducted numerous static tests, applying DC currents ranging from 0.5A to 1.5A to both the 20-turn and 30-turn stator designs. During these tests, I meticulously recorded voltage drops, resistances, and characterized their thermal performance in still air, noting significant temperature rises (which could exceed 200∘C on the 20-turn stator at 1.5A before considering the Temperature Coefficient of Resistance). Subsequently, I performed all dynamic tests, operating the 30-turn stator with a 1A DC current while varying rotor speeds from 0 up to 3000 RPM. These dynamic tests were instrumental in evaluating the cooling efficacy of rotor-induced airflow. The experimental data I collected and analyzed demonstrated a significant maximum temperature reduction of 45.58∘C at the hottest stator location and achieved an overall cooling efficiency of up to 45.28% at 3000 RPM, thereby validating a key project hypothesis.

Throughout this intensive project, I was responsible for the rigorous collection and initial analysis of these thermal performance metrics, which were critical in understanding the stator's behavior under load and the effectiveness of different rotor speeds on heat dissipation. As the Quality Assurance Coordinator, I focused on ensuring the reliability and accuracy of our experimental data. This involved constant monitoring during tests, troubleshooting issues with the setup or instrumentation, and identifying operational challenges, such as the severe vibrations that unfortunately limited our testing speeds to 3000 RPM, well below our 9500 RPM design target. My hands-on involvement was crucial in providing the empirical data that underpinned our project's findings and recommendations. Through this experience, I not only honed technical skills in microcontroller programming (Arduino, ESP32), sensor integration (thermocouples, MAX6675), PCB design (Altium), CAD modeling, and experimental data analysis, but also gained invaluable experience in managing the iterative process of engineering design, the critical importance of robust instrumentation, overcoming practical hardware and software integration challenges in a team environment, and rigorously validating system performance against design goals.