There is a task to drop and pick up a payload for the 2026 VFS DBVF (Design-Build-Vertical-Flight) competition. Our team, CWRU VTOL, wanted to test several ideas out, so I developed an electromagnetic payload drop-and-pickup system.

Reliable payload release and re-acquisition was challenging within the power, integration, and alignment constraints. 

Process

I first estimated required magnetic holding force needed from inertial and aerodynamic loads with an applied factor of safety.

Then, I validated magnet performance empirically using a lab bench power supply, a force scale, and steel plate.

I had to consider landing terrain, alignment tolerances, geometry, and clearances to ensure consistent pickup under non-ideal conditions.

There was bench and flight-adjacent testing to refine performance and reliability.

Intermittent sticking due to residual magnetization became an issue, preventing release in some cases. 

I solved this with an H-bridge control strategy using current reversal and tapered ramp-down to de-magnetize the steel plate.

I prioritized clean cable management and control via PWM input from a standard Pixhawk for straightforward system integration.

Results