Variable-Pitch Quadrotor

Fixed-pitch quadrotors are popular research and hobby platforms largely due to their mechanical simplicity relative to other hovering aircraft. This simplicity, however, places fundamental limits on the achievable actuator bandwidth and the possible flight maneuvers. This project shows that many of these limitations can be overcome by utilizing variable-pitch propellers on a quadrotor. I performed a detailed analysis of the potential benefits of variable-pitch propellers over fixed-pitch propellers for a quadrotor. This analysis is supported with experimental testing to show that variable-pitch propellers, in addition to allowing for generation of reverse thrust, substantially increase the maximum rate of thrust change. I also developed a nonlinear, quaternion-based control algorithm for controlling the quadrotor with an accompanying trajectory generation method that finds polynomial minimum-time paths based on actuator saturation levels. I implemented the control law and trajectory generation algorithms on a custom variable-pitch quadrotor, utilizing my own autopilot. Flight tests highlight the benefits of a variable-pitch quadrotor over a standard fixed-pitch quadrotor for performing aggressive and aerobatic maneuvers.

The videos below show the prototype variable-pitch quadrotor that I built. The quadrotor is controlled using the developed trajectory generation algorithms.


Since this work was completed, several commercial variable-pitch quadrotors (like this one and this one) have become available, further validating the original idea.

Media

My variable-pitch quadrotor was featured on several websites such as Gizmodo, Hackaday, and DIY Drones.

Fails

It probably goes without saying, but the variable-pitch quadrotor didn't always work. One of the most notable fails was when our autopilot power distribution board short-circuited during a crash, causing the battery to ignite. You can see the burn marks on the autopilot and the floor.

Get in Touch

@inproceedings{Michini11_ICRA,
  author = {Michini, Bernard and Redding, Josh and Ure, N. Kemal and Cutler, Mark and How, Jonathan P.},
  title = {Design and Flight Testing of an Autonomous Variable-Pitch Quadrotor},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
  year = {2011},
  pages = {2978--2979},
  month = {May},
  url = {http://markjcutler.com/papers/Michini11_ICRA.pdf}
}
@article{Barrett09_EJLA,
  title = {Minimum rank of edge subdivisions of graphs},
  author = {Barrett, Wayne and Bowcutt, Ryan and Cutler, Mark and Gibelyou, Seth and Owens, Kayla},
  journal = {Electronic Journal of Linear Algebra},
  volume = {18},
  pages = {530--563},
  year = {2009},
  url = {http://markjcutler.com/papers/Barret09_EJLA.pdf}
}
@inproceedings{Chen15_ICRA,
  address = {Seattle, WA},
  author = {Chen, Yufan and Cutler, Mark and How, Jonathan P.},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
  month = {May},
  title = {Decoupled Multiagent Path Planning via Incremental Sequential Convex Programming},
  year = {2015},
  url = {http://markjcutler.com/papers/Chen15_ICRA.pdf}
}
@inproceedings{Chowdhary12_GNC,
  author = {Chowdhary, Girish and Wu, Tongbin and Cutler, Mark and Ure, N. Kemal and How, Jonathan},
  title = {Experimental Results of Concurrent Learning Adaptive Controller},
  booktitle = {AIAA Guidance, Navigation, and Control Conference (GNC)},
  year = {2012},
  address = {Minneapolis, MN},
  month = {August},
  pages = {1--14},
  note = {Invited},
  url = {http://markjcutler.com/papers/Chowdhary12_GNC.pdf}
}
@inproceedings{Chowdhary13_ICRA,
  author = {Chowdhary, Girish and Wu, Tongbin and Cutler, Mark and How, Jonathan P.},
  title = {Rapid Transfer of Controllers Between {UAVs} using Learning Based Adaptive Control},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
  year = {2013},
  pages={5409--5416},
  month={May},
  address={Karlsruhe, Germany},
  url = {http://markjcutler.com/papers/Chowdhary13_ICRA.pdf}
}
@inproceedings{Cutler10_GNC,
  title = {Energy Harvesting and Mission Effectiveness for Small Unmanned Aircraft},
  author = {Cutler, Mark and McLain, Timothy W and Beard, Randal W and Capozzi, Brian},
  booktitle = {AIAA Guidance, Navigation, and Control Conference (GNC)},
  pages = {1--13},
  address = {Toronto, Canada},
  month = {August},
  year = {2010},
  url = {http://markjcutler.com/papers/Cutler10_GNC.pdf}
}
@inproceedings{Cutler11_GNC,
  author = {Cutler, Mark and Ure, N. Kemal and Michini, Bernard and How, Jonathan P.},
  title = {Comparison of Fixed and Variable Pitch Actuators for Agile Quadrotors},
  booktitle = {AIAA Guidance, Navigation, and Control Conference (GNC)},
  year = {2011},
  address = {Portland, OR},
  month = {August},
  pages = {1--17},
  url = {http://markjcutler.com/papers/Cutler11_GNC.pdf}
}
@inproceedings{Cutler12_GNC,
  author = {Cutler, Mark and How, Jonathan P.},
  title = {Actuator Constrained Trajectory Generation and Control for Variable-Pitch Quadrotors},
  booktitle = {AIAA Guidance, Navigation, and Control Conference (GNC)},
  year = {2012},
  address = {Minneapolis, Minnesota},
  month = {August},
  pages = {1--15},
  url = {http://markjcutler.com/papers/Cutler12_GNC.pdf}
}
@mastersthesis{Cutler12_Masters,
  author = {Cutler, Mark},
  title = {Design and Control of an Autonomous Variable-Pitch Quadrotor Helicopter},
  school = {Massachusetts Institute of Technology, Department of Aeronautics and Astronautics},
  year = {2012},
  month = {August},
  url = {http://markjcutler.com/papers/Cutler12_Masters.pdf}
}
@inproceedings{Cutler13_ICUAS,
  author = {Cutler, Mark and Michini, Bernard and How, Jonathan P.},
  title = {Lightweight Infrared Sensing for Relative Navigation of Quadrotors},
  booktitle = {International Conference on Unmanned Aircraft Systems (ICUAS)},
  year = {2013},
  pages = {1156--1164},
  address = {Atlanta GA},
  month = {May},
  url = {http://markjcutler.com/papers/Cutler13_ICUAS.pdf}
}
@inproceedings{Cutler13_NIPS,
  author = {Cutler, Mark and Walsh, Thomas J. and How, Jonathan P.},
  title = {Reinforcement Learning with Multi-Fidelity Simulators (Poster)},
  booktitle = {NIPS Transfer and Multi-Task Learning Workshop},
  month = {December},
  year = {2013}
}
@inproceedings{Cutler14_ICRA,
  author = {Cutler, Mark and Walsh, Thomas J. and How, Jonathan P.},
  title = {Reinforcement Learning with Multi-Fidelity Simulators},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
  year = {2014},
  address = {Hong Kong},
  pages = {3888--3895},
  month = {June},
  url = {http://markjcutler.com/papers/Cutler14_ICRA.pdf}
}
@article{Cutler15_TRO,
  author = {Mark Cutler and Thomas J. Walsh and Jonathan P. How},
  journal = {IEEE Transactions on Robotics},
  title = {Real-World Reinforcement Learning via Multifidelity Simulators},
  year = {2015},
  month = {June}, 
  volume = {31}, 
  number = {3}, 
  pages = {655-671},
  url = {http://markjcutler.com/papers/Cutler15_TRO.pdf}   
}
@article{Cutler15_DSMC,
  author = {Mark Cutler and Jonathan P. How},
  journal = {ASME Journal of Dynamic Systems, Measurement and Control},
  title = {Analysis and Control of a Variable-Pitch Quadrotor for Agile Flight},
  year = {2015},
  month = {October}, 
  volume = {137}, 
  number = {10}, 
  pages = {101002--101002-14},
  url = {http://markjcutler.com/papers/Cutler15_TRO.pdf}
}	
@inproceedings{Cutler15_ICRA,
  address = {Seattle, WA},
  author = {Cutler, Mark and How, Jonathan P.},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
  month = {May},
  title = {Efficient Reinforcement Learning for Robots using Informative Simulated Priors},
  year = {2015},
  url = {http://markjcutler.com/papers/Cutler15_ICRA.pdf}
}
@inproceedings{Michini13_ICRA,
  author = {Michini, Bernard and Cutler, Mark and How, Jonathan P.},
  title = {Scalable Reward Learning from Demonstration},
  booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
  year = {2013},
  month = {May},
  address = {Karlsruhe, Germany},
  pages = {303--308},
  url = {http://markjcutler.com/papers/Michini13_ICRA.pdf}
}
@inproceedings{Thomson09_ASM,
  title = {Experiment-Based Optimization of Flapping Wing Kinematics},
  author = {Thomson, Scott L. and Mattson, Christopher A. and Colton, Mark B. and Harston, Stephen P. and Carlson, Daniel C. and Cutler, Mark},
  year = {2009},
  month = {January},
  booktitle = {AIAA Proceedings of the 47th Aerospace Sciences Meeting},
  pages = {1--8},
  url = {http://markjcutler.com/papers/Thomson09_ASM.pdf}
}
@inproceedings{Ure13_ICUAS,
  author = {Ure, N. Kemal and Chowdhary, Girish and Chen, Yu Fan and Cutler, Mark and How, Jonathan P. and Vian, John},
  title = {Decentralized Learning based Planning Multiagent Missions in Presence of Actuator Failures},
  booktitle = {International Conference on Unmanned Aircraft Systems (ICUAS)},
  year = {2013},
  address = {Atlanta GA},
  month = {May},
  pages={1125--1134},
  url = {http://markjcutler.com/papers/Ure13_ICUAS.pdf}
}