In this paper, an ornithopter prototype that mimics the flapping motion of bird flight is developed, and the lift and thrust generation characteristics of different wing designs are evaluated. This project focused on the spar arrangement and material used for the wings that could achieves improved performance. Various lift and thrust measurement techniques are explored and evaluated. Various wings of insects and birds were evaluated to understand how these natural flyers with flapping wings are able to produce sufficient lift to fly. The differences in the flapping aerodynamics were also detailed. Experiments on different wing designs and materials were conducted and a paramount wing was built for a test flight. The first prototype has a length of 46.5 cm, wing span of 88 cm, and weighs 161 g. A mechanism which produced a flapping motion was fabricated and designed to create flapping flight. The flapping flight was produced by using a single motor and a flexible and light wing structure. A force balance made of load cell was then designed to measure the thrust and lift force of the ornithopter. Three sets of wings varying flexibility were fabricated, therefore lift and thrust measurements were acquired from each different set of wings. The lift will be measured in ten cycles computing the average lift and frequency in three different speeds or frequencies (slow, medium and fast). The thrust measurement was measure likewise but in two cycles only. Several observations were made regarding the behavior of flexible flapping wings that should aid in the design of future flexible flapping wing vehicles. The wings angle or phase characteristic were analyze too and studied. The final ornithopter prototype weighs only 160 g, has a wing span of 88.5 cm, that could flap at a maximum flapping frequency of 3.869 Hz, and produce a maximum thrust and lift of about 0.719 and 0.264 N respectively. Next, we proposed resonance type flapping wing utilizes the near resonance phenomenon of a two-degree of freedom elastic system, that is, the wing is supported by the springs for flapping and feathering motions. Being oscillated close to the resonance frequency of the system, only by the torque in flapping motion, the amplitude gained is a few times higher than that of normal case. The first prototype was made from acrylic using a laser cutting machine. The wings were made up of carbon rods and kite material Ripstop. First test showed that the wings were too heavy for the mechanism to work. The third prototype was a smaller single gear crank design which was fabricated using a 3D printer. Initial test proved that the second prototype could withstand the high frequency flapping and near resonance amplitude as designed. With remote control, the third prototype was able to take off, climb, cruise and land in flapping mode successfully.

An analysis of the kinematics of a flapping membrane wing using experimental kinematic data is presented. This motion capture technique tracks the positon of the retroreflective marker(s) placed on the left wing of a 1.3-m-wingspan ornithopter. The time-varying three-dimensional data of the wing kinematics were recorded for a single frequency. The wing shape data was then plotted on a two-dimensional plane to understand the wing dynamic behaviour of an ornithopter. Specifically, the wing tip path, leading edge bending, wing membrane shape, local twist, stroke angle and wing velocity were analyzed. As the three characteristic angles can be expressed in the Fourier series as a function of time, the kinematics of the wing can be computationally generated for the aerodynamic study of flapping flight through the Fourier coefficients presented. Analysis of the ornithopter wing showed how the ornithopter closely mimics the flight motions of birds despite several physical limitations.

Both the unsteady flow and acoustic characteristics of the albatross-like flapping wing were numerically investigated. The flow around the flapping wing was predicted by using ANSYS FluentÒ unsteady three-dimensional compressible Navier-Stokes equations. The acoustic field was calculated by a built-in acoustic package, based on the FfowcsWilliams-Hawkings (FW-H) acoustic analogy. During the start-up motion, the large start-up vortices dominate the otherwise quiescent field with minimal sound generated. The sound is generated by the rotational and tangential motions of the wing using different sound generation mechanisms. A primary dipole tone at wing beat frequency is generated by the rotational motion, while other dipole tones at higher frequencies are produced by the vortex scattering at the trailing-edge of the wing during the tangential motion. The frequency composition of the primary tone changes with the pitching angle of the wing. During the steady flapping state, the quadruple sound is produced more due to the wake vortex interaction. The far-field sound spectrum is of broader bandwidth. The sound produced propagates only for short distance.

This paper presents research and development of our in-house object detection program for a digital camera that can be used in conjunction with a microprocessor on a micro aerial vehicle for autonomous flight in an indoor environment. The object detection program functions to create object boundaries and edges found in the video recorded by the camera. Thus creating boundaries of an environment. This work will use video and image analysis techniques to build colour co-relations and edges of the objects. The results from the analysis can then be passed to the microprocessor for processing. This then enables the micro aerial vehicle to be able to avoid and head towards objects in its surrounding autonomously. In our work, we also develop a 3D indoor navigation system, which is able to aid MAVs to safely navigate through the unknown and complicated indoor environment and complete autonomously necessary flight missions. The main tasks of this work involves hardware construction of an embedded navigation system (including multiple sensors, data and image processing units, and data and video links), the development and realization of robust 3D indoor navigation algorithms, and the tests of the system on the actual MAV platforms. In the navigation scheme, sophisticated machine vision algorithms such as robust feature extraction, an optical flow method and stereo vision approach are utilized to stabilize the MAVs and avoid the obstacles. The output of multiple sensors including inertial measurement sensors, visual sensors, and range sensors are employed to realize the 3D simultaneously localization and mapping (SLAM) for MAVs.

This paper presents a part of our ongoing development of a butterfly-like ornithopter (flapping wing) micro-aerial vehicle (MAV). Two kinds of butterfly were selected for studies: Monarch butterfly (Danaus plexippus) and Swallowtail butterfly (Papilio troilus)). The Monarch butterfly is well-known for its ability for long distance migratory flight. The Monarch butterfly is well-known for its high agility. It is also selected as baseline for comparison. The Swallowtail butterfly has unique tails (streamers) at the trailing edge of its hind wings. For both types of butterfly, the flow physics show that during free flights, they use a variety of unconventional aerodynamic mechanisms to generate force: wake capture, two different types of leading-edge vortex, active and inactive upstrokes. Free-flying butterflies often used different aerodynamic mechanisms in successive strokes. For Swallowtail butterflies, the streamer appears to help their flight more stable, by aligning the wake vortices behind its hind wings. The subsequent horse-shoes vortices also help create more vortex lift. For flexible wing, the result from fluid-structure interaction shows that the swallowtail butterfly deflect more than Monarch butterfly.