Analysis of Limit-cycle Phenomenon Caused by Actuators Non Linearity

W.C. Leite Filho and A.M. Bueno (Brazil)


Actuators, nonlinear model, parameter identification, limit-cycle.


. The attitude control of space vehicles is fundamental to accomplish a mission. This system faces several types of problems, among them stands out actuator's nonlinearities. The actuator's (movable nozzle) nonlinearities cause the limit-cycle phenomenon, which impairs the control system design. This work aims to analyze the limit-cycle phenomenon and determine the parameters of actuator which cause it. In order to do that, it is presented a method of identification based on the first harmonic analysis and data obtained from hardware in the loop simulation. The describing function approach leads to analytical solution to obtain nonlinear parameters. Digital simulation using such results is compared to hardware in the loop tests and shows the validation of the method.

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