SBIR Phase I: Control Strategy for Parallel Hybrid Multirotor

The broader impact/commercial potential of this Small Business Innovation Research (SBIR) Phase I project is the development of a drone propulsion technology potentially capable of a 10X improvement in flight duration over all-electric heavy-lift solutions with other significant advantages. The initial market for this technology will be unmanned solutions for wildland firefighters. Applications include on-demand logistics solutions for supplies and large-area controlled ignition solutions, and ultimately around-the-clock air support for firefighters, where currently only 8 hours of air support per day is available. It has been suggested that every 10% reduction in time to contain a fire is worth approximately $300 M in savings in suppression costs alone. The overall wildfire suppression market in the US is estimated at $6.5 B, and additional opportunities exist in the the commercial unmanned air system market (estimated to grow to $34 B by 2022) and urban air mobility. This Small Business Innovation Research (SBIR) Phase I project will enable the development of a new UAS propulsion technology leading to new capabilities and missions. Electric-only multi-rotors offer limited flight for heavy lift applications, with the typical duration for a fully loaded electric multi-rotor of 15-20 minutes. One solution is serial hybrid multi-rotors with a generator added to the electric powertrain, but these systems suffer from low efficiency and low power-to-weight ratio. The combined parallel/serial hybrid approach eliminates many of the power conversion steps and components, yet retains the benefits of electric propulsion. The result is an estimated 1.54X gain in efficiency, lower mass, and higher power-to-weight ratio. The research objectives are to develop the control algorithm for parallel hybrid multi-rotor control, implement this scheme on a prototype aircraft, quantify overall system efficiency, and quantify flight performance. It is anticipated that parallel hybrid control of propeller angular velocity to be within +/- 1% of electric-only control. We also anticipate flight performance of the prototype system to have measured Control Power (CP) rates of 30 deg/s, 50 deg/s, and 60 deg/s for pitch, roll, and yaw, respectively. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.