Amnon Katz

Flight Model for Unmanned Simulated Helicopters

This paper presents a flight model for use in simulating computer generated helicopters. Momentum and energy balance is used to define a rotor thrust envelope. The four basic control inputs take the form of thrust components and the sideslip angle. Time integrations are performed for the three center of mass degrees of freedom only. Six degrees of freedom information is derived for the visual displays. The model can inexpensively function in real time and faster than real time. Validity is demonstrated by comparing model performance predictions with published data.

A blade element model in a low cost helicopter simulation

The equations for a blade element helicopter rotor model are presented. The model was developed a t the University of Alabama Flight Dynamics Lab for use in real-time and off-line simulation. This blade element model simulates the trajectories of the individual rotor blades and allows the representation of some transient effects that are not included in some other models.

Event correlation for networked simulators

The timing and synchronization issues of networked simulation over large distances are studied. It is shown that the absolute time-stamp is effective in removing inconsistencies between the world pictures presented by the networked simulators. The tolerance that can be maintained on correlation errors is dominated by the precision of the dead-reckoning process over a time span that is the sum of propagation delay and clock error. Dead-reckoning statistics are invoked to determine the level of correlation that can be achieved for global networking. The clock accuracy required for this purpose is assessed.

Estimation of Wind from Airplane States in Coordinated Flight

A e lter is dee ned that extracts the wind aloft from the Earth velocity and the orientation of a e ight vehicle in coordinated e ight (data that are available in the context of distributed interactive simulation ). A convergence theorem is proved stating that the estimated wind monotonically approaches the true wind when the latter is horizontal and constant. The e lter builds the transverse component of the wind and converges to the full wind as the e ight vehicle changes heading. The fastest convergence occurs when the e lter is applied at heading intervals equal to a critical interval that depends on the bank.