Papers by Keyword: Yaw

Abstract: Aircraft morphing with regard to UAVs has recently gained incredible momentum; however, only a limited amount of research has been conducted on its effect on tailless aircraft. This is partly due to aerodynamic compromises such as directional instabilities that arise in the absence of a vertical stabilizer. Yet birds readily adapt to adverse flight conditions without vertical stabilizers and are unhindered with respect to stability and maneuvering due to their smooth continuous shape change and rapid muscle response. This research, motivated by the discrepancy between manmade and natural flight designs, investigates the aerodynamic effects of a smart morphing horizontal tail exhibiting bending-twisting coupling for yaw control on a bio-inspired aircraft. The structural response due to actuation was determined using Abaqus and coupled with a Reynolds-averaged-Navier-Stokes turbulence model for a low-Reynolds-number fluid analysis of the deformed shape. The morphing tail was simulated as piezoelectric Macro Fiber Composites with oriented PZT rods. Directional moment and stability derivative are presented to gain insight into the effect of the morphing horizontal tail on yaw control.

Abstract: To be able to more accurate analysis aerodynamic characteristic variation under yaw of NREL Phase VI wind turbine. The influence of yaw on the aerodynamic characteristic by using a three-dimensional unsteady CFD methods based sliding mesh in this paper. To flow, the overall performance and Cp of the three-dimensional flow numerical simulation were compared with experimental results with the same wind speeds to confirm the reliability of the model at a given axial wind speed conditions. In the yaw conditions, the effect of yaw on the aerodynamic performance of wind turbine blades, changing law and reveal the aerodynamic performance is in the flow details and rules in different azimuth.

Abstract: This paper derives the kinematic equations of 2 DOF articulated vehicle based on D-H method. When unilateral wheels of the articulated vehicle surmounting the depth cavity, the path is studied by simulation and experiment. The experiment result shows when the articulated vehicle surmounts the cavity of 0.46m, there is a yaw angle about 5o and the motion direction yaws. By calculating the differential kinematic equations, it is founded that the wheel-ground contact angles in both sides of the front (or rear) wheels change differently, which leads to the rotation around the vertical axis and yaw. Finally, we analyze the experiment and simulation errors.

Abstract: Wind power is an important direction of new energy, which has no pollution, no consuming fossil fuels, and no producing waste, which is widely used at this stage of clean energy. The small stand alone wind power has been paid more and more attention due to its low cost, flexible installation, strong adaptability. This paper introduces the mechanical and electrical structure, which are used in KW level stand alone mode wind turbine automatically track and yaw system. The motion rules and control strategies of the tracking and yaw system are discussed and then the control program flow is provided. The PIC16F873 chip is used as controller for this part in this system. It can fully meet the design requirements, which will reduce costs and increase the system's control ability. This system can automatically track and yaw, according to the wind direction and wind power.

Abstract: In this paper, a FEA model of non-normal(considering yaw angle and oblique angle) penetration into reinforced concrete is established by using software ANSYS/LS-DYNA. In order to validate the digital model which is sensitive to material parameters,mesh size,ect. Amounts of numerical simulations are performed. The numerical results of a process of peneration are compared with the experimental results, and a good agreement is obtained.In the study,the residual velocity and the ballistic attitude when a projectile penetrates into a reinforced concrete target are focused on, the relationship between positive yaw angle and negative yaw angle with the penetration capacity of the projectile is investigated. The results obtained by the numerical approach are useful for predicting the response of the penetration, and the proposed numerical simulation methods may be very beneficial to some experiment of perforation of reinforced concrete structures.

Abstract: Study Algorithm of roll, pitch and yaw angular velocity for three-axis gyroscope. the gyro have only one sensitive quality, can sensitize the three axial angular velocity of the rotating carrier at the same time. in the case of gyro’s spin angular velocity presence and pitch or yaw angular velocity worked, gyro output signal contain spin, pitch and yaw angular velocity. Through Uniaxial Gravity Accelerometer’s application, the roll, pitch and yaw angular velocity for three-axis gyroscope can be demodulated.

Abstract: This letter suggests a method to improve tracking performance of an H-type XY stage with air bearings and flexure hinge mechanisms. The flexure hinge mechanisms are employed to prevent failure of the air bearings when the yaw motion error of the H-type stage is controlled using a control algorithm called gantry control. Adoption of the flexure hinge mechanism combined with the gantry control leads to occurrence of mutual ripple. Ripple should be handled to obtain good tracking performance. Modeling of the mutual ripple and simulation of two compensation algorithms are presented.

Abstract: In order to detect the rolling、pitch and yaw angle of high-speed-spin vehicle, a novel attitude sensor system is designed by using a digital signal processor TMS320F2812. The configuration of the sensor consists of two MEMS sensing elements and signal processing circuit and micro-processor. A new silicon MEMS gyroscope based on the Coriolis effect can sense three angular rate of spin vehicle, which can provide a synthesis signal, including roll, yaw and pitch angular rate. And a MEMS accelerometer reacts on demodulating the three angular rates. The design of the hardware circuit, the algorithm and implement of software are presented. The demodulation algorithm is validated by simulation experiment on the ground and the experimental results are presented.

Abstract: The torque of the continuously variable transmission system with friction drive mechanism is transmitted by contacting roller with input and output disks. For the higher transmitted torque, it is necessary to apply large load in order to get higher friction force, which in turn generates severe high stress on the contact surfaces of roller and disks. The toroidal type CVT system has simple component arrays that have three contact points between roller and each input or output disk to get the torque transmitted. However, compact assembly design of the three sets of rollers contacting with input and output disks needs the roller to stay with unsymmetrical angled position with each other. Therefore, the contact shapes between roller and disk vary according to the transmission ratio and should be investigated to avoid the excessive contact stress over than ~1.8 GPa. In this study, the contact geometries of roller and disks in the toroidal type CVT system are computed during the gear ratios. The contact area of which the size depends on the material elasticity, curvatures of roller and disk, and applied load are all of elliptic shapes because of the convex and concave curvatures of roller and disk shapes, respectively. From the computed results considering the size of roller diameter, roller stroke and applied load, it is found that the shapes of contact area changes the sizes of major and minor elliptical diameters in the rolling direction during the gear ratios due to the unsymmetrical angled position of roller.