We have been working on the realization of our idea since our Focus-Project “Adaptive Helicopter Landing Gear” started in the middle of September. We are going to present a functional prototype on the 30th of Mai at the yearly Focus-Roll-out at ETH. We are using an unmanned helicopter from Aeroscout as a prototyping platform.
Our prototype consists of four individually controllable legs, guaranteeing stability and adaptability. They are however not actively steered by the pilot but adapt autonomously to the unevenness of the ground. The complete system is designed with the goal of not significantly reducing the payload of the helicopter it is mounted on- neither is it extremely heavy nor does the system occupy important space for mounting payload. A safe landing is always possible, even in case of a partial or total failure of the electronic components, since the brakes are closed in the non actuated state.
Landing on slopes exceeding 20 degrees of inclination are possible.
Our system should be able to clear obstacles with a difference in height of up to 50cm.
The landing system autonomously adapts to the ground without any input from the pilot.
The feet are modularly exchangeable to enable maximal grip on various surfaces.
The model shows our basic geometrical concept, based on a parallelogram. The advantage of such a structure is that the leg's tip moves up and down on a vertical line. Thus, the foot's contact point does not move horizontally while adapting to the uneven surroundings. Furthermore, the structure is almost solely strained along the longitudinal direction in each element, enabling both a lightweight and stable construction. The leg's actuation is built into the parallelogram structure such that the forces to move it can be produced by small lightweight actuators.
We developed and designed our custom drive train to fulfill all of our requirements, the most important of which are the weight restriction and the capability of compensating the large forces occurring during a rough landing. We use a damper to absorb the released energy, mechanically decoupled from fragile parts such as the motor. This makes the complete system much more secure and more robust.
We use force control to interact with the ground during the adaption phase. This enables us to maintain a significantly small force on the main body and therefore almost no additional moments act on the main body, enabling the pilot to land as with a state of the art landing gear. A stable positioning of the legs is reached when the force on each leg is almost equal. An advantage of force control is the ability to instantly react to soft ground and slipping.
In the third and final year of the Bachelor’s program in Mechanical Engineering at ETH Zurich, the students can decide between doing a Focus-Project and a Focus-Specialization. The aim of the Specialization is widening the theoretical knowledge in a certain engineering field. Focus-Projects on the other hand allow students to apply the knowledge acquired during the Bachelor’s program to find an optimal solution to a complex problem. This goal is accomplished by tackling the different steps of product development in a practical context.
The complete Focus-Project team is made up of students in Mechanical Engineering and is completed by students from other departments at ETH, the Zürcher Hochschule für Angewandte Wissenschaften (ZHaW) and the Zürcher Hochschule der Künste (ZHdk).
The final goal of a Focus-Project is presenting a fully functional prototype at the Roll-out presentation on the 30th of May. It is however possible and likely that successful and promising projects are further pursued after the Roll-out. This date merely means the end of the Focus-project.
Examples of previous Focus-Projects: