Vertebrate Flight Mechanics Physiology Morphology Ecology And Evolution

Motion-induced oscillations of crane payloads seriously degrade their effectiveness and safety. For the transport of a large object, the payload is modeled as a distributed-mass model, and is typically attached to the hook by four rigging cables. The manipulation task can be more challenging because of the payload swing toward the driving direction and the payload twisting about the rigging cables. The dynamics of bridge cranes transporting distributed-mass payloads are derived. A control scheme is designed for suppressing both the payload swing and twisting. Simulations of a large range of motions and various system parameters are used to analyze the dynamic behavior and the robustness of the control scheme. Experimental results obtained from a bridge crane transporting distributed-mass crate validate the simulated dynamic behavior and the effectiveness of the control scheme.

Control of Bridge Cranes With Distributed-Mass Payload Dynamics

Insect-inspired, tailless, hover-capable flapping-wing robots: Recent progress, challenges, and future directions

Flapping wing micro air vehicles (MAVs) take inspiration from natural fliers, such as insects and hummingbirds. Existing designs manage to mimic the wing motion of natural fliers to a certain extent; nevertheless, differences will always exist due to completely different building blocks of biological and man-made systems. The same holds true for the design of the wings themselves, as biological and engineering materials differ significantly. This paper presents results of experimental optimization of wing shape of a flexible wing for a hummingbird-sized flapping wing MAV. During the experiments we varied the wing 'slackness' (defined by a camber angle), the wing shape (determined by the aspect and taper ratios) and the surface area. Apart from the generated lift, we also evaluated the overall power efficiency of the flapping wing MAV achieved with the various wing design. The results indicate that especially the camber angle and aspect ratio have a critical impact on the force production and efficiency. The best performance was obtained with a wing of trapezoidal shape with a straight leading edge and an aspect ratio of 9.3, both parameters being very similar to a typical hummingbird wing. Finally, the wing performance was demonstrated by a lift-off of a 17.2 g flapping wing robot.

https://iopscience.iop.org/article/10.1088/1748-3190/aa5c9e/pdf

Experimental optimization of wing shape for a hummingbird-like flapping wing micro air vehicle

https://opus.lib.uts.edu.au/bitstream/10453/100178/4/OE-D-15-00651_Revised_ManuscriptQH.pdf

Fuzzy sliding mode control of an offshore container crane

Hovering flapping flight is inherently unstable and needs to be stabilized actively. We present a control mechanism that modulates independently the wing flapping amplitude and offset by displacing joints of a flapping linkage mechanism. We demonstrate its performance by high speed camera recordings of the wing motion as well as by direct measurements of pitch moment and lift force. While flapping at 17 Hz the prototype produces 90 mN of lift and generates pitch moments from -0.7 N.mm to 1.1 N.mm. The mechanism shows low level of cross-coupling in combined pitch and roll commands.

https://journals.sagepub.com/doi/pdf/10.1260/1756-8293.6.4.253

Pitch and roll control mechanism for a hovering flapping wing MAV

Analysis of the stick-slip vibration of a new brake pad with double-layer structure in automobile brake system

A simplified model of the system of unbalanced rotors coupled with pendulum rod is examined. The model consists of two counter-rotating rotors, a rigid pendulum rod and a rigid vibrating body, which is horizontally connected to a fixed support by means of springs. The synchronous state of the system, i.e. synphase and antiphase synchronization of the rotors, is studied by means of the Poincare method. Moreover, the assessment of the synchronous state is converted to find a solution that should satisfy a balanced function and a stability function of the system. However, frequency ratios and installation angular are included in the two functions. It is demonstrated that the spring stiffness and the installation angular have a large influence on the existence and stability of the synchronization state in the coupling system. Finally, computer simulations are preformed to verify the theoretical computations.

/pdf/study-of-synchronization-for-a-rotor-pendulum-system-with-43xopzpe17.pdf

Study of synchronization for a rotor-pendulum system with Poincare method

Micro Air Vehicles (MAVs) with flapping wings try to mimic their biological counterparts, insects and hummingbirds, as they can combine high agility manoeuvres with precision hovering flight. Near-hovering flapping flight is naturally unstable and needs to be stabilized actively. We present a novel mechanism for pitch moment generation in a robotic hummingbird that uses wing twist modulation via flexible wing root bars. A custom build force balance, sensitive enough to measure the cycle averaged pitch moment as well as lift force, is also presented. The introduced prototype mechanism generates pitch moment of up to ± 0.5 mNm. Finally we integrate a Shape Memory Alloy (SMA) wire to actuate the wing root bar ends. We present achievable displacement versus bandwidth as well as generated pitch moment.

https://journals.sagepub.com/doi/pdf/10.1260/1756-8293.5.4.299

Yanghai Nan

Papers

Experimental optimization of wing shape for a hummingbird-like flapping wing micro air vehicle

Pitch and roll control mechanism for a hovering flapping wing MAV

Analysis of the stick-slip vibration of a new brake pad with double-layer structure in automobile brake system

Study of synchronization for a rotor-pendulum system with Poincare method

Pitch Moment Generation and Measurement in a Robotic Hummingbird