Abstract:In view of the PIO (PilotInducedOscillation) problem prone to occurrence in ultralowaltitude airdrop, a closedloop system with actuatorrate limitation is established, and the formula of PIO of the closedloop system is deduced. Based on the synchronization and Neal-Smith model and the different actuator saturation values, the descriptive function method and the GAP criterion are used to predict the PIO trend. The results show that the PIO prediction results are different for different pilot models. Compared with the NealSmith pilot model, the synchronous control model is more effective, and predicted by the simultaneous control model. When the absolute gain of the driver is greater than 11.5, the closedloop system is unstable and prone to PIO problems. If the PIO is induced by the pilot, the occurrence of PIO can be effectively avoided by reducing the manipulated gain for the pilot. Within the reasonable and permissible range, The limit value avoids the occurrence of PIO to a certain extent.