DroneGear: A Novel Robotic Landing Gear With Embedded Optical Torque Sensors for Safe Multicopter Landing on an Uneven Surface

One of the most serious disadvantages of the vertical takeoff and landing flying robots including multicopters is the necessity of the flat stable area for safe landing. The ability to land and takeoff from uneven surfaces and moving basements would help the rotorcrafts in many important applications. The special landing gears are used to provide rotorcrafts this ability. This letter explores multicopter landing on uneven surfaces using a novel adaptive landing platform DroneGear. The DroneGear contains four compliant robotic legs of two degrees of freedom each. The innovative optical torque sensor is integrated into the knee joint of each leg to provide timely adaptation to rough terrain in an unknown environment. Additionally, inertial measurement unit is embedded into the passive footpad of each leg for estimation of relief profile in the landing zone. The results of the experiments show that the DroneGear can be successfully used for the safe hexacopter landing on the different angle slopes, plane, step surfaces, and for terrain profile estimation as well.