Mechatronic Design of a High-Performance Propeller for Bi-Directional Thrust

MSc assignment

Project Supervisor: Prof. Antonio Franchi Co-Supervisors: (Engineering Staff, TBD)

Keywords: Mechatronics, Aerial Robotics, Actuator Design, System Modeling, Rapid Prototyping

1. The Challenge: A Bottleneck in Aerial Robotics

Standard multirotor drones, while agile, are limited by their propellers. These fixed-pitch actuators have a quadratic thrust-to-speed relationship ( $F \propto \omega^2$ ), which is efficient for simple flight but creates a major bottleneck for advanced robotic applications.

Specifically, this quadratic curve has a zero-derivative at the zero-thrust point. This makes it impossible to quickly or smoothly reverse the direction of thrust, as the actuator loses all control sensitivity. This is a major problem for:

Aerial Physical Interaction: Tasks requiring precise push/pull forces against a surface.
Omnidirectional Flight: Platforms that fly in any orientation, where propellers must constantly operate near or across the zero-thrust point.

2. Project Goal: A Novel Mechatronic Actuator

Existing solutions are not ideal. Reversing the motor is too slow, and Active Variable-Pitch (AVP) systems (like a helicopter's) are extremely complex, heavy, and prone to failure.

This project's goal is to design a novel "third path." We aim to create a new type of propeller that achieves the high-performance, bi-directional, and linear thrust control of an AVP system, but with the simplicity and robustness of a single-motor design. The objective is to fundamentally reshape the thrust-speed curve through smart mechatronic design, embedding the desired dynamic behavior directly into the propeller's hardware.

3. Thesis Scope and Objectives

This is an explorative, high-impact project at the intersection of mechanical design, system theory, and experimental robotics. The student will:

1. Modeling & Theory: Develop and refine the mathematical model for a novel propeller mechanism, exploring how to achieve the target bi-directional, linear thrust profile.
2. Mechatronic Design & Prototyping: Design and build a proof-of-concept prototype of the new propeller system using rapid prototyping tools (e.g., 3D printing, compliant mechanisms).
3. Experimental Validation: Design and build a test bench using a force-torque sensor to measure the propeller's thrust-speed characteristic curve.
4. Analysis & Iteration: Compare the experimental results against the theoretical model and the target performance. Based on these findings, you will iterate on the design to improve its performance.

The ultimate deliverable is a functional hardware prototype that successfully demonstrates a high-performance, bi-directional thrust response from a single motor.

5. Ideal Candidate Profile

This project is ideal for a student with a strong background in mechatronics and a passion for hands-on, practical work. You should be comfortable with:

Mechanical design (CAD) and rapid prototyping (3D printing).
System modeling and simulation (MATLAB/Simulink).
Integrating hardware (sensors, motors) and low-level coding (C/C++, Arduino, or similar).
A "theory-to-practice" mindset, using rigorous modeling to inform and improve a physical hardware build.

6. Contact

Prof. Antonio Franchi <a.franchi@utwente.nl>