Abstract: Yaw attitude dynamics equation of strato-heric- telecommunication-platform—unmanned dirigible airship are built according to the forces and moments acted on. The above piecewise functions are formulated by hybridize logical dynamics equation. Yaw attitude modulation is judged by tracking error. In case that yaw attitude is greatly modulated, assistant thrust system take out assistant moment, PID control via pole assignment modulates the airship great yaw attitude in order to make the closed loop system have needed specified dynamic performance and highly reliability. Otherwise, rudder steering angle is changed, sliding mode variable structure controller designed according to equivalent control principle reversely modulates little yaw attitude in order to make the closed loop system have good robustness. Reasonable assigned pole of PID and defined sliding surface parameter, 0-1 logical triggering switch succeeds in concording the two control application in reciprocal operating condition which avoids such phenomenon as tremble, unstability during the course of control mode switch. The digital simulation proves control means and the concord in reason.

Key words: Hybridize logical dynamics modeling, PID control, Sliding mode variable structure, Stratospheric telecommunication platform