A study of the kinematic characteristics a three degree-of-freedom (dof) parallel mechanism is presented. The architecture comprised mobile platform attached to base through identical prismatic-revolute-spherical jointed serial linkages. prismatic joints are considered be actuated. These actuators lie on common plane and have radial directions action. mechanism’s inverse displacement solution obtained. Since has only 3 dof, constraint equations describing inter-relationship between six...

Changes in the design of software algorithms for generating physical motion flight simulators have typically been put forward on grounds improved cueing. Little attention has paid to more practical criteria such as computational cost, ease adjustment, or evaluation by experienced pilots a realistic simulation environment. A comparison three most commonly found literature performed: classical washout, optimal control, and coordinated adaptive. This consisted pilot evaluations these...

Small unmanned aerial vehicles (UAVs) come in many types, the most common being fixed-wing and rotorcraft. Most of these are powered by brushless dc motors driving fixed-pitch propellers. Since thrusters typically quite powerful, relative to weight aircraft, motion UAVs is usually dominated thruster dynamics. It therefore becomes particularly important have a good model thruster, which can be assembled based on simple measurements system properties, rather than from exhaustive testing. This...

The real-time control of cooperating manipulators, mechanical hands, and walking machines involves the optimization an underdetermined force system subject to both equality inequality constraints. constraints arise as a result passive frictional contacts in systems that depend on these for transmission, or when taking into account limited torque capability actuators. Since results are used provide setpoints actuators, they must be obtained real time. A technique is presented solving...

We present the results of a study aimed at determining simulation realism that might be achieved using reduced-degree-of-freedom flight simulator motion bases. More specifically, quality produced by two different three-degree-of-freedom platforms was compared to conventional six-degree-of-freedom Stewart platform. The bases investigated were spherical mechanism allowing only rotational motions, as well base capable heave, pitch, and roll motions. To compare bases, three characteristic...

To accurately simulate the motion of slack marine cables, it is necessary to capture effects cable’s bending and torsional stiffness. In this paper, a computationally efficient novel third-order finite element presented that provides representation both accelerates convergence model at relatively large sizes. Using weighted residual approach, discretized equations for new cubic are developed. Applying inter-element constraint equations, we demonstrate how an assembly these elemental can be...

The use of physical motion in flight simulation is still a much debated topic. This paper investigates the more narrow issue its application commercial jet transport simulators. We have attempted to quantify perceptions airline pilots about quality possible when number different motion-drive algorithms are tested on simulator employing state-of-the-art six-degrees-of-freedom motion-base. Four broad categories were tested: classical washout, optimal control, coordinated adaptive, and...

This paper proposes a modeling approach for the nonlinear dynamics simulation of airships. The flight mechanics, aerostatics, and aerodynamics are incorporated into model. A comprehensive estimation method is provided aerodynamics, including added-mass terms, viscous effect, forces on fins, hull due to axial drag. program developed from model applied analyze control responses Skyship-500 airship. comparison between test results different inputs shows that gives reasonable behavior. then...

The large adaptive reflector is a Canadian design concept for new type of large-scale radio telescope. This telescope would be composed made individually actuated panels and multitethered feed platform held aloft by an aerostat. paper focuses on the position orientation control platform. Models both cables are first derived. Then, strategy adapted to particular system's dynamics designed. based cascade-control architecture, in which inner loop adjusts tension each cable. controller...

A new dynamics modeling approach is proposed for flexible airships, which integrates the flight dynamics, structural aerostatics, and aerodynamics. In particular, a comprehensive aerodynamic computation presented, including potential-flow aerodynamics, viscous effects, forces on fins, hull due to axial drag. The coupling between flexibility aerodynamics incorporated through local velocity of deformed airship. resulting model represented by single set nonlinear ordinary differential...

This paper investigates the ability of a quadrotor to maneuver in wind field. A dynamic model is presented its motion. The includes effect quantify on dynamics quadrotor. proportional-integral-derivative (PID) controller shown as baseline typically used quadrotors. LQR then an alternative PID controller. These two controllers are compared simulation environment using and simulated disturbances. Both found have similar performance field, though be easier tune.

Purpose – The purpose of this paper is to develop a physics-based model for UAV propellers that capable predicting all aerodynamic forces and moments in any general forward flight condition such as no flow, pure axial flow side etc. Design/methodology/approach methodology adopted the widely used Blade Element Momentum Theory (BEMT) propeller development. difficulty arising from variation induced with blade’s angular position overcome by supplementing BEMT inflow developed Pitt Peters. More...

Ground effect on rotary aircraft has been studied for many decades. Although a large body of research results is now available conventional helicopters, this topic just beginning to receive attention in the unmanned aerial vehicle community, particularly small size UAVs. The objective paper assess applicability widely-used ground model, developed middle last century, predicting UAV. particular employed work, Draganflyer X8, actuated by 8 propellers arranged 4 coaxial pairs quadrotor...

Recent interest in high-angle-of-attack flight, aerobatic maneuvering, vertical/short takeoff and landing, etc., of small unmanned aerial vehicles necessitates more detailed modeling the complex aerodynamics associated with these flight regimes. This includes effect propeller slipstream, also called prop wash, which is main source airflow that helps maintain lift control during near-zero forward-speed like encountered as well flight/aerobatic maneuvering hovering. Propeller slipstream models...

The constraint performance analysis in the limited kinetostatic subspace of parallel manipulators is a significant but ignored issue. motion/force constrainability analysis, with focus on lower-mobility manipulators, subject this study. Via theory screws, three generalized frame-invariant indices are proposed based concept power coefficient. introduced can not only identify singularity and fully constrained property also measure closeness between particular pose an unconstrained...