Zone-based unmanned aerial vehicle landing systems and methods

A system, comprising:

• an unmanned aerial vehicle (UAV) configured to operate in a plurality of operational zones, each of the plurality of operational zones being associated with a range of altitudes, the UAV comprising a plurality of sensors, the UAV comprising a controller, a processor and memory for storing executable instructions, the processor executing the instructions to:
• cause the UAV to pass through the plurality of operational zones in a sequential manner from a highest altitude operational zone to a lowest altitude operational zone to land on the target location;
• determine when an error has occurred when the UAV is passing through one of the plurality of operational zones;
• and
• cause, in response to the error, the UAV to retreat from a current operational zone of the plurality of operational zones to a higher-altitude operational zone of the plurality of operational zones,
• wherein the controller determines that an error has occurred using proportional navigation where the controller determines a line of sight vector between the UAV and the target location,
• and wherein when rotation of the line of sight vector is at or above a threshold the controller causes the UAV to retreat to the higher-altitude one of the plurality of operational zones.

A method for landing an unmanned aerial vehicle (UAV), comprising:

• establishing a plurality of operational zones, each of the plurality of operational zones being associated with a range of distances from a target location;
• guiding an unmanned aerial vehicle (UAV) through each of the plurality of operational zones to land the UAV on the target location using sensors, wherein the sensors are configured to sense a distance between the UAV to the target location or an orientation between the UAV and the target location, wherein portions of the sensors are configured for use at different altitudes;
• and
• determining an error for the UAV during landing, wherein the UAV retreats to an operational zone having a greater distance than a current operational zone when the error is determined, and wherein determining the error includes determining a line of sight vector between the UAV and the target location, and wherein when rotation of the line of sight vector is at or above a threshold the UAV retreats to a higher altitude operational zone.