STABILITY AUGMENTATION SYSTEM FOR RELAXED STATIC STABILITY AIRCRAFT

摘要

ABSTRACT OF THE DISCLOSUREThe outputs of a pair of linear accelerometers areutilized to provide measures of craft vertical acceleration andbody axis pitch angular acceleration. The pitch angularacceleration signal is integrated to provide a measure of bodyaxis pitch rate. The pitch rate signal is in turn integratedto provide a measure of body axis pitch attitude. An earthreferenced pitch attitude sensor provides a measure of earthreferenced pitch attitude and through a rate taker a measureof earth referenced pitch rate. The earth referenced sensoris utilized to calibrate out errors and effectively align thelinear accelerometers so that in the event of a loss of theearth referenced sensor, the calibrated accelerometers haveadequate accuracy to compute pitch rate and pitch attitudewithin the long period bandwidth needed to provide thestability augmentation function for a relaxed static stabilityaircraft. The earth referenced and body axis pitch ratesignals are blended and the earth referenced and body axispitch attitude signals are blended whereby steady statedifferences therebetween are washed out through a long timeconstant washout, the earth referenced signals dominating inthe steady state. The linear vertical acceleration andangular acceleration signals and the blended pitch rate andpitch attitude signals are combined in a control law to drivethe craft elevator servo. Failure of the earth referencedattitude sensor results in a graceful degradation of thecontrol law to washed out body axis attitude and attituderate control.