scholarly journals A method for evaluating the wind disturbance rejection capability of a hybrid UAV in the quadrotor mode

2019 ◽  
Vol 11 ◽  
pp. 175682931986964
Author(s):  
Hang Zhang ◽  
Bifeng Song ◽  
Haifeng Wang ◽  
Jianlin Xuan
Keyword(s):  
Disturbance Rejection ◽  
Large Scale ◽  
Propulsion System ◽  
Equilibrium Analysis ◽  
Static Equilibrium ◽  
Wind Disturbance ◽  
Equilibrium Equations ◽  
Moment Arms ◽  
Thrust And Torque ◽  
Maximum Thrust

The wind disturbance rejection capability of a quadrotor fixed-wing hybrid unmanned aerial vehicle (QFHUAV) in the quadrotor mode is an important factor restricting its large-scale applications. In this paper, based on static equilibrium analysis of the quadrotor mode of a QFHUAV with a wind disturbance, a method for analyzing and evaluating the wind disturbance rejection capability of the QFHUAV in the quadrotor mode is presented. The six degrees-of-freedom (6-DOF) static equilibrium equations of the QFHUAV are established in headwind and crosswind situations. The maximum wind velocity that satisfies the equilibrium equations under the constraints of the maximum thrust and torque of the quadrotor propulsion system is used to determine the wind disturbance rejection capability of the QFHUAV in the quadrotor mode. A QFHUAV with a twin-boom is used as an example to analyze and evaluate its wind disturbance rejection capability in the quadrotor mode. The configuration parameters, quadrotor propulsion system parameters, and aerodynamic parameters affecting the wind disturbance rejection capability of the QFHUAV in the quadrotor mode are presented, discussed, and explained. The yawing moment from the wind disturbance is the main factor threatening the safe flight of the QFHUAV in the quadrotor mode. The rotor disk angle, the maximum thrust of the quadrotor propulsion system, and the moment arms of the components of the quadrotor propulsion system thrust are the main factors affecting the wind disturbance rejection capability of the QFHUAV in the quadrotor mode. Increasing these parameter values is an effective approach to improve the wind disturbance rejection capability of the QFHUAV in the quadrotor mode. From the perspective of wind disturbance rejection capability, tailless and X-type layouts are better choices for QFHUAVs. The correctness of results obtained by the proposed method is verified by two flight test schemes.

A Finger Model with Constant Tendon Moment Arms

1993 ◽  
Vol 37 (10) ◽  
pp. 710-714 ◽  
Author(s):  
Koo-Hyoung Lee ◽  
Karl H.E. Kroemer
Keyword(s):  
Sagittal Plane ◽  
Virtual Work ◽  
Static Equilibrium ◽  
Principle Of Virtual Work ◽  
Finger Movements ◽  
Equilibrium Equations ◽  
Finger Joints ◽  
Moment Arms ◽  
Finger Model

A kinematic finger model was developed with the assumption that the tendon moment arms at the finger joints were constant, and that the finger moved in the sagittal plane. Equations of static equilibrium for the model, derived using the principle of virtual work, were indeterminate. The number of variables was reduced based on the muscular activities in finger movements. The finger strengths were computed from the equilibrium equations, and mathematically expressed as functions of finger positions, tendon moment arms, and lengths of phalanges. Experiments were performed to measure finger strengths, and the measured finger strengths were compared to the computed results.

scholarly journals Static Analysis of Large-Scale Multibody System Using Joint Coordinates and Spatial Algebra Operator

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Mohamed A. Omar
Keyword(s):  
Equilibrium Position ◽  
Large Scale ◽  
Multibody System ◽  
Initial Conditions ◽  
Differential Algebraic Equations ◽  
Equilibrium Analysis ◽  
Static Equilibrium ◽  
Connectivity Matrix ◽  
Load Prediction ◽  
Joint Coordinates

Initial transient oscillations inhibited in the dynamic simulations responses of multibody systems can lead to inaccurate results, unrealistic load prediction, or simulation failure. These transients could result from incompatible initial conditions, initial constraints violation, and inadequate kinematic assembly. Performing static equilibrium analysis before the dynamic simulation can eliminate these transients and lead to stable simulation. Most exiting multibody formulations determine the static equilibrium position by minimizing the system potential energy. This paper presents a new general purpose approach for solving the static equilibrium in large-scale articulated multibody. The proposed approach introduces an energy drainage mechanism based on Baumgarte constraint stabilization approach to determine the static equilibrium position. The spatial algebra operator is used to express the kinematic and dynamic equations of the closed-loop multibody system. The proposed multibody system formulation utilizes the joint coordinates and modal elastic coordinates as the system generalized coordinates. The recursive nonlinear equations of motion are formulated using the Cartesian coordinates and the joint coordinates to form an augmented set of differential algebraic equations. Then system connectivity matrix is derived from the system topological relations and used to project the Cartesian quantities into the joint subspace leading to minimum set of differential equations.

Walking Machine Design Based on Certain Aspects of Insect Leg Design

1992 ◽  
Author(s):  
E. F. Fichter ◽  
D. R. Kerr
Keyword(s):  
Control System ◽  
Observational Data ◽  
The Body ◽  
Static Equilibrium ◽  
Machine Design ◽  
Ground Contact ◽  
Careful Attention ◽  
Equilibrium Equations ◽  
Walking Machine ◽  
Leg Design

Abstract A walking machine design originating from observations of insects is presented. The primary concept derived from insects is a leg used to apply force to the body without applying significant moments about the point of body attachment. This is accomplished with legs which have kinematic equivalents to ball-and-socket joints at body attachment and ground contact, with joints in the middle which only change distance between body and ground. Standing and walking with 6 legs of this design requires careful attention to static equilibrium equations but does not necessitate a control system which actively distributes forces to the legs. This paper considers necessary observational data, assumptions on which control is based, mathematical development for control and problems such as foot slip.

scholarly journals Experiences with inquiry-based learning in an introductory mechanics course

2018 ◽  
Author(s):  
Devin R. Berg
Keyword(s):  
Lessons Learned ◽  
Student Response ◽  
Equilibrium Analysis ◽  
Static Equilibrium ◽  
Educational Approach ◽  
Engineering Technology ◽  
Student Work ◽  
Inquiry Based Learning ◽  
Technology Students ◽  
Wide Range

Inquiry-based learning is an educational approach that allows the student to take ownership over the education process by self-identifying a problem and formulating their own solution. The application of this method of teaching was explored in an introductory mechanics course taken by both engineering and engineering technology students. Students were tasked with applying the principles of fundamental static equilibrium analysis to objects found in their normal surroundings. The deliverable for this assignment consisted of a photograph of an object they found to be in static equilibrium and a short description of how the state of the object could be described mathematically. Student submissions for this task exhibited a wide range of quality and imagination. Examples of student work are presented along with discussion of lessons learned and recommendations for the use of this method in the future. The overall student response to this task was positive and thus these efforts will be expanded.

scholarly journals Biofuels, poverty, and growth: a computable general equilibrium analysis of Mozambique

2009 ◽  
Vol 15 (1) ◽  
pp. 81-105 ◽  
Author(s):  
CHANNING ARNDT ◽  
RUI BENFICA ◽  
FINN TARP ◽  
JAMES THURLOW ◽  
RAFAEL UAIENE
Keyword(s):  
Computable General Equilibrium ◽  
Poverty Reduction ◽  
Large Scale ◽  
Green Light ◽  
Equilibrium Analysis ◽  
Unskilled Labor ◽  
Percentage Points ◽  
Land Rents ◽  
Biofuels Policy ◽  
Capital Intensive

ABSTRACTThis paper assesses the implications of large-scale investments in biofuels for growth and income distribution. We find that biofuels investment enhances growth and poverty reduction despite some displacement of food crops by biofuels. Overall, the biofuel investment trajectory analyzed increases Mozambique's annual economic growth by 0.6 percentage points and reduces the incidence of poverty by about 6 percentage points over a 12-year phase-in period. Benefits depend on production technology. An outgrower approach to producing biofuels is more pro-poor, due to the greater use of unskilled labor and accrual of land rents to smallholders, compared with the more capital-intensive plantation approach. Moreover, the benefits of outgrower schemes are enhanced if they result in technology spillovers to other crops. These results should not be taken as a green light for unrestrained biofuels development. Rather, they indicate that a carefully designed and managed biofuels policy holds the potential for substantial gains.

Dynamics Redesign of Marine Structures

1985 ◽  
Vol 29 (04) ◽  
pp. 285-295 ◽  
Author(s):  
Curtis J. Hoff ◽  
Michael M. Bernitsas
Keyword(s):  
Large Scale ◽  
Structural Changes ◽  
Dynamic Equilibrium ◽  
Degree Of Freedom ◽  
Attractive Alternative ◽  
Equilibrium Equations ◽  
Element Analysis ◽  
Solution Methods ◽  
Tower Model ◽  
Energy Equations

The dynamic response of a marine structure depends upon the exciting forces and the modal characteristics of the structure. Excessive vibratory response requires reduction of the exciting loads or redesign of the structure or both. In this paper the general redesign problem is formulated. It applies to large-scale structures and allows for large structural changes. Solution of the redesign problem is achieved through perturbation methods which are an attractive alternative to traditional trial-and-error methods. Perturbation solution methods are based on dynamic equilibrium equations or energy equations or both. A new method based on the energy equations which enforces the mode orthogonality conditions is developed and evaluated against all existing methods. Two test cases, a 191-degree-of-freedom two-dimensional ship model and a 810-degree-of-freedom offshore light tower model are used to compare the methods numerically. It is shown that the method developed in this paper can produce, with a single finite element analysis of the baseline system, a structure which satisfies within acceptable limits all nonconflicting design objectives.

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