Micro-Aerial Vehicle (MAV) Research : Designing An Ornithopter for Urban Search and Rescue
Student: Soon Yu Sheng
Supervisor: Dr. Tomonari Furukawa
1. Introduction
An ornithopter is a device that flaps its wings to fly. This gives it the capability to hover around a fixed position like a helicopter. The difference between an ornithopter and a helicopter however, is that the ornithopter requires less energy and thus is more fuel efficient as compared to regular helicopters. By designing an ornithopter specialized in urban search and rescue it enables the rescuers to obtain aerial data of a catastrophe zone and provide assistance as soon as possible.
2. Objective
There are 2 objectives:
- Reducing the weight of the ornithopter.
-
Conducting research on other flapping mechanisms.
2.1 Reducing the Weight
The aim is to be able to reduce the weight of the ornithopter to less than 10g. This is achieved by replacing the parts previously made of wood to carbon fibers. The first prototype was built based on this principle with minor changes to the body structure. The joints were made of wood while the wooden beams were replaced by carbon fibers. This proved to be too weak as the structure swayed greatly and was not rigid enough to house the motor and the battery. The wing was also not well constructed enough as there were too much overlap and there were too much creases and wrinkles due to lack of tension in the wing.
Fig 1. First prototype of the MAV
Fig 2. Second prototype of the MAV
Due to that, the second prototype was constructed using only carbon rods for the main structure. The body structure was built according to research done on bridge structures.
Fig 3. Body structure of the second prototype
However, the wings were still not taut enough. Thus additional carbon rods were placed on the wing to make the wings more taut. Finally, the final design was completed and the motor and gears were assembled. The overall weight of the device was a little less than 10g, thus the set target was achieved.
Component |
Old model’s wt (g) |
Component |
New model’s wt (g) |
6mm 4.5Ohm motor |
1.3 |
6mm 4.5Ohm motor with Gear box 5.8 gear ratio |
2.4 |
Li Poly Cell 90mAh |
3 |
Li Poly Cell 90mAh |
2.8 |
Balsa Structure + tissue wings |
6 |
Carbon fiber Structure + Mylar wings |
4.1 |
Electronics |
3 |
Blue tag |
0.5 |
Gear box 26.6 reduction |
0.9 |
|
|
Total |
14.2 |
Total |
9.8 |
Table 1. Comparison between the weight of the old model and the new model
Fig 4. Refined wing structure with motor assembled
2.2 Researching other flapping mechanisms
The standard flapping mechanism involves the wings beating up and down in the vertical plane. However, when conducting research on insects, it has been discovered that insects do not have their wings just beating up and down, instead they move in a sweeping broom movement, as shown in the figure below:
Fig. 5 Insect wing flapping motion
Ref: Chopra, I., Leishman, J.G., Ramasamy, M., Singh, B., 2004, Insect-Based Flapping Wings for Micro Hovering Air-Vehicles: Experimental Investigations, Alfred Gessow Rotorcraft Center, Department of Aerospace Engineering, University of Maryland, USA.
3. Testing and Further Work
| Stages |
1st Prototype |
2nd Prototype |
2nd Prototype with refined wing structure |
| Average Distance |
1m |
3m |
5m |
Table 2. Comparison of gliding distance between each prototype
Further testing had been done with the motor and gearbox installed and it yielded an increased distance of about 7m, however adjustments to the wing structure should yield even better results. These adjustments have yet to be completed at this stage of the project.
Further work on imitating the insect wing flapping motion had been conducted using LEGO, but the full potential of this mechanism have yet to be implemented.
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