COBEM99

S8 Engenharia Aeroespacial

Title:

FLIGHT CONTROL LAW DESIGN WITH AND WITHOUT PRE-DECOUPLING

Summary :

A SATELLITE LAUNCHER FLIGHT CONTROL LAW THAT TRACKS A REFERENCE ATTITUDE AND MAINTAINS ATTITUDE RESPONSE DECOUPLING WAS DESIGNED. THE DESIGN FIRST DECOUPLES THE SYSTEM AND THEN THE TRACKER IS DESIGNED BY LINEAR QUADRATIC OPTIMAL CONTROL METHOD. THE DESIGN WAS ASSESSED RESPECT TO FLYING QUALITIES IN THE TIME DOMAIN AND IN THE FREQUENCY DOMAIN. AN ALTERNATIVE STUDY ABOUT HOW TO DESIGN THE SAME CONTROL LAW THAT NOT ONLY KEEP FOLLOWING A REFERENCE ATTITUDE BUT ALSO MAINTAINS ATTITUDE DECOUPLING DUE TO THE VEHICLE MANOEUVRES HAS BEEN PERFORMED. HOWEVER, THIS ALTERNATIVE METHOD DOES NOT MAKE A PRE-DECOUPLING OF THE SYSTEM, BUT INSTEAD DIRECTLY PERFORMS THE DESIGN, AGAIN BY LINEAR QUADRATIC OPTIMAL CONTROL METHOD. IT HAS BEEN NOTICED IN BOTH DESSIGNS, THAT IN ORDER TO ACHIEVE THIS OBJECTIVE IT IS NECESSARY TO USE A LINEAR COUPLED MODEL TO CARRY ON THE CONTROL LAW DESIGN, INSTEAD OF THE USUAL LINEAR UNCOUPLED MODEL USED TO DESIGN A REGULAR TRACKING CONTROL LAW. A COMPARISON OF THE SYSTEM STABILITY WORKING WITH BOTH CONTROL LAWS HAS BEEN PERFORMED, AS ALSO THE FLIGHT PERFORMANCE OF BOTH DESIGNS. BY THE END OF THE WORK SOME STUDIES ABOUT HOW TO IMPLEMENT BOTH CONTROL LAWS HAVE ALSO BEEN STUDIED, AS THE ADVANTAGES AND DISADVANTAGES OF EACH APPROACH. IN WHIS WORK BOTH DESIGN METHODS ARE APPLIED FOR THE BRAZILIAN VLS STUDY.

Author :

Leite Filho, Waaldemar C.
Oliva, Alvaro P.

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