As a proof of concept, we developed a system that uses a video game joystick to control the Human Drone during flight. One of the joystick buttons is being used to capture control (overriding the radio) and the other is used to "return" the control back to the radio (the system's fall-safe also returns control to the radio). The transition will only be performed with the positions of the roll, pitch, and yaw sticks in the center, both on the radio and on the joystick (which is simple to place, as the springs guarantee their central position in both systems).
Although the position of the radio's throttle stick does not necessarily always coincide with the joystick's throttle stick at the time of transition, the algorithm guarantees a smooth transition, that is, without an abrupt change in power. This way the pilot has time to match the power set over the radio before the transition.
The advantage of this system is that someone on the ground will be able to control the vehicle in the event of a joystick system failure. Don't worry, we'll test this a lot before actually flying.