This paper introduces a new method of providing motion cues to a moving base six-degree-of-freedom flight simulator utilizing nonlinear filters. Coordinated adaptive filters, used to coordinate translational and rotational motion, are derived based on the method of continuous steepest descent, and the basic concept of the digital controllers used for the uncoordinated heave and yaw cues is also presented. The coordinated adaptive washout method is illustrated by an application in a six-degree-of-freedom fixed-base environment. Nomenclature: angular position break point, rad = aircraft body axis translational accelerations, m/sec 2 : angular velocity threshold, rad/sec : coefficient for position penalty in cost function, per sec 4 : angular velocity washout rate, rad/sec 2 : coefficient for velocity penally in cost function, per sec 2 : damping parameters for second-order translational washout, rad/sec : frequency parameters for second-order translational washout, rad/sec 2 : inertial axis translational acceleration commands, m/sec 2 : body axis longitudinal and lateral acceleration at motion simulator centroid location, m/sec 2 : body axis vertical acceleration (referenced about Ig) at motion simulator centroid location, m/sec 2 P,q,r PV,I;PV t = gravitational constant, m/sec 2 = longitudinal and lateral cost function = digital controller gain parameter 3 = longitudinal gain parameters ,3 = lateral gain parameters = body axis angular velocity commands, rad/sec = body axis aircraft angular velocities, rad/sec -longitudinal adaptive parameters = lateral adaptive parameters = time, sec -arbitrary time, set; = angular rate weighting coefficient, m 4 /rad 2 sec 2 -commanded inertial translational position of motion simulator, rn -commanded inertial angular position of motion simulator, rad = angular velocity input commands, rad/sec j = time when \j/ reaches breakpoint, A, sec T. IntroductionA NEW method of providing motion cues to a moving base six-degree-of-freedom flight simulation has been developed at Langley Research Center. The method, coordinated adaptive washout, is based on the idea of coordination of rotation and translation to obtain accurate longitudinal and lateral force cues in a manner similar to the work of Schmidt and Conrad. 1 ' 2 The major differences between the subject scheme and the work of Schmidt and ;|;A dot over a variable indicates the time derivitive of that variable.Downloaded by UNIVERSITY OF OKLAHOMA on February 4, 2015 | http://arc.aiaa.org |

National attention has focused on the critical problem of detecting and avoiding windshear since the crash on 2 Aug. 1985 of a Lockheed L-1011 at Dallas/Fort Worth International Airport. As part of the NASA/FAA National Integrated Windshear Program, we have defined a measurable windshear hazard index that can be remotely sensed from an aircraft, to give the pilot information about the wind conditions he will experience at some later time if he continues along the present flight path. A technology analysis and end-to-end performance simulation measuring signal-to-noise ratios and resulting wind velocity errors for competing coherent laser radar (lidar) systems have been carried out. The results show that a Ho:YAG lidar at a wavelength of 2.1 microm and a CO(2) lidar at 10.6 microm can give the pilot information about the line-of-sight component of a windshear threat from his present position to a region extending 2-4 km in front of the aircraft. This constitutes a warning time of 20-40 s, even in conditions of moderately heavy precipitation. Using these results, a Coherent Lidar Airborne Shear Sensor (CLASS) that uses a Q-switched CO(2) laser at 10.6 microm is being designed and developed for flight evaluation in the fall of 1991.

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