Research On The Impact Of Communication Delay On Engine Performance In Distributed Control System

Future aircraft engine control systems will be based on a distributed architecture, in which, the sensors and actuators will be connected to the controller through an engine area network. Distributed engine control architecture enables the use of advanced control techniques along with achieving weight reduction, improvement in performance and lower life cycle cost. The performance of distributed engine control system is predominantly dependent on the performance of communication network. The communication network will introduce some constraints, such as network-induced delay and data dropouts, which degrade the performance of the control system or in worst case, may even destabilize the control system. The main contents of this paper are as follows.Firstly, current centralized FADEC structure and various signals transmitted in the system were described. The centralized control system was the basis for distributed control system architecture and bus communicatio. Three different architectures for turbine engine control system based on a distributed framework were presented. A partially distributed engine control system for a turbofan engine was designed.Secondly, the communication network of distributed control system was studied. A set of guidelines are presented in this dissertation based on the comparison study. TTCAN, a general time-triggered standardization of Controller Area Network(CAN) was selected as the alternative communication bus. Communication bandwidth assessment and schematic design were conducted for a turbofan engine. True Time was exploited to develop a distributed control system simulation. Network delay and data dropout impact on the engine performance was studied.Then,a control design was proposed to stabilize the distributed turbine control system under the communication constraints. The system stability condition and maximum allowable delay were presented under Lyapunov stability theorem. The output feedback gains were obtained by solving linear matrix inequalities to ensure stability under conditions of network-induced time delay and random data loss. A reconfigurable fault tolerant control design was proposed to compensate both the time delay and data dropouts, which was applied for a nonlinear engine model. The results proved effective.Finally, a hardware in the loop simulation was carried out to verify the impact of time delay and data dropouts on the system performance. The effectiveness of the designed controller was verified under the hardware environment as well.