Adaptive Helicopter Landing Gear Final Product

############################# Video Source: www.youtube.com/watch?v=JtoOWS18D3k

Concept • The adaptive landing gear consists of four legs with one degree of freedom each. This enables the adaption to the terrain and provides sufficient tilt resistance. This makes landings on hills with slopes exceeding 20° possible. The landing gear also enables overcoming up to 50 cm tall obstacles. An unmanned helicopter designed by Aeroscout was used as a platform. • Platform • The Scout B-100 is an ideal prototyping platform. Due to its empty weight of 50 kg and a rotor span of 3.2 m, the Scout B-100 belongs to the category of the Light Unmanned Rotorcraft Systems . It is equipped with an 18 PS two-stroke motor and can carry up to 28 kg of payload and fuel. • Features of the Adaptive Landing Gear • Autonomy • No input by the pilot is necessary during the landing procedure. This is a must for the system, since the pilot is already fully occupied during this stage of flight. With a single “Gear Down” input, the operation of the system is virtually as easy as todays retractable landing gears. • Dynamics • Each leg is controlled individually, allowing an optimal adaption to uneven terrain. Due to the use of force control, the adaption is fast and smooth. • Modularity • The modular design of the feet enables quick and simple adjustments for special operation areas such as snow and ice. For easy maneuvering on the ground, the use of wheels is possible as well. • Safety • In the case of partial or complete system failure, the position of the landing gear is still secured. This is accomplished by the use of safety brakes and a redundant control unit. • Stability • The system is robust enough to withstand a drop from 35 cm without any damage. This is possible due to the use of high strength materials and a high-performance damper. • Weight • The total weight adds up to 15 kg which is substantially less than other systems with comparable functionality. • Geometry • The animation shows our concept consisting of a parallelogram with adapted side lengths. The lengths were optimized to allow a vertical movement of the foot with as little lateral offset using only one degree of freedom. Thus, the point of contact's lateral movement is negligible while the system compensates the unevenness of the terrain. • Drivetrain • The legs are driven by a custom-built linear actuator consisting of an electric motor driving a ball screw. A brake can stop the movement of the ball screw. In series, a damper is installed to absorb the high loads occurring during hard landings. With an operating weight of only 1.2 kg per leg, loads of 300 kg can be carried. • Control • The adaption to the terrain during landings is achieved using force control. Logging the current induced, the motor enables registering ground contact. On contact, each leg is raised until all legs report contact. Then, the orientation of the helicopter is regulated using an IMU and finally all brakes are closed. • Result • The prototype was tested extensively on the testing setup as well as in flight. Wooden pallets were used as obstacles. All testing scenarios could be completed successfully. The inclination of the rotor after landing could be kept below 5°. Thus, the functionality of the concept was proven effectively. • Outlook • This project was carried out as a Focus-Project at ETH Zurich. Towards the end of 2017, the results will be published. Further work on the system will be conducted by means of semester and master theses. A commercial use of the technology is not yet at hand. • Film Production • MAX.Films • Stay connected with us: • http://www.athlas.ethz.ch • / projectathlas

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