Guaranteed Performance Anti-disturbance Control For Flexible Airbreathing Hypersonic Vehicles Under Multiple Constraints

Flexible air-breathing hypersonic vehicles(FAHV)have been regarded as the keys of space-aeronautics incorporation technology in the 21 st century,owing to its competences including hypersonic cruise speed(larger than 5 Mach),strong maneuverability as well as far attack range and its widespread applications such as penetration,long-range transportation and delivery,as well as strategic striking.A control technology with high performances(high robustness and strong adaptability)plays a fatal role in FAHV cruise and mission completion.However,FAHV dynamics is characterized as a multivariable system with high nonlinearity,strong coupling,fast time varying,and large uncertainties,whose complexity of kinetics,unknown flight surroundings,and multiple constraints induce unprecedented challenges into FAHV controller design listed as follows:a)Constraints of system states: Note that overlarge overshoot of velocity and altitude and overlong convergence time will deteriorate FAHV trajectory tracking performance.Besides,the overlarge response of angle of attack(Ao A)will lead to a lack of airflow to be inhaled for ensuring efficient supersonic combustion of scramjet.b)Constraints of airborne computational resources: Control methodology with excessive complexity is not suitable for airborne microchip with scarce computational resources.c)Constraints of magnitude and bandwidth of control input: Overlarge control input will surpass the accessible range of actuators,making control system be an open-loop control system.Digital communication channel cannot transmit signal with infinite precision.d)Constraints of execution efficiency: Owing to the cruise surroundings of FAHV has a stratosphere height,where the thin air density will cause low execution efficiency of elevator.Currently,fruitful investigations have been reported aiming at FAHV controller design with the aid of Lyapunov stability theory,while there is still rare results devoted for FAHV control designs with full considerations of aforesaid multiple constraints.As a consequence,it is still an open issue to study an advanced controller strategy for FAHV in parrel with full considerations of multiple constraints.To this end,supported by Youth Program of National Natural Science Foundation of China “Anti-disturbance tracking control theory and method for hypersonic flight vehicle with multiple disturbances and constrained angle of attack,” this dissertation devises a guaranteed performance anti-disturbance control for flexible air-breathing hypersonic vehicles under multiple constraints from the perspectives of robustness,safety,optimality,and fault tolerance,while the closed-loop stability has been proved via Lyapunov stability analysis.1.Guaranteed-cost anti-disturbance control for FAHV considering prescribed tracking performanceIn order to solve the FAHV control problem under multi-source interference environment and considering the limitation of airborne communication resources,based on prescribed performance mechanism,hysteresis quantizer and minimum parameter learning neural network,a quantitative guaranteed-cost anti-disturbance control mechanism is designed with immeasurable initial system states.The innovations of proposed method are presented as follows:1)In order to effectively solve the issue that the current FAHV controllers are difficult to reflect the physical characteristics of actual digital control system,under the classical backstepping control framework,the hysteresis logarithmic quantizer is first embedded into FAHV controller-to-actuator channel to obtain control signal with finite precision.To effectively reduce the communication data size without sacrificing the tracking performance,a compensation term is incorporated in a robust control law to eliminate the adverse effects induced by quantization errors.2)In addition,to circumvent the limitation of traditional controllers that the transient and steady-state tracking performance cannot be prespecified,and to pursue a trajectory tracking meeting the preset performance indices,based on prescribed performance control method proposed by Bechlioulis,an improved prescribed performance control technique is presented for FAHV by merits of hyperbolic cosecant function,such that the exact information of initial system states is no longer required with tracking profiles satisfying preselected indices.2.Chattering reduction control for FAHV with prescribed performanceTo address the inherent problem existing in current prescribed performance control that intense chattering is inevitable in face of a fast convergence speed,a chattering reduction prescribed performance control is proposed for FAHV,whose contributions can be summarized as follows:In order to ensure a prescribed fast tracking performance for FAHV without enticing strong chattering in control signals,a prescribe performance control equipped with a behavior function governed within time-optimal framework is proposed,such that the inability of current prescribed performance control designs to achieve a fast tracking performance with smooth control signals can be solved.3.Input-and-measurement guaranteed-cost control for FAHV with partial state constraintsFocusing on the issue of state constraints(velocity,altitude,and Ao A)and the unreasonable communication resource dissipation in both input and measurement channels in previous FAHV controller designs,this dissertation establishes an input-and-measurement guaranteed-cost control for FAHV with partial state constraints,whose contributions are listed as follows:1)An intermittent measurement-based extended state observer(IMESO)is proposed for FAHV to realize an online disturbance estimation with a reduced communication resource occupation and a competitive approximation accuracy compared with existing ESO-based reports,while the quantitative relationship between the upper bounds of estimation errors and the parameters of event-based sampler is derived to facilitate the parameter tuning process.Moreover,different from the existing event-triggering results utilizing a relative threshold sampler,an input-and-measurement event-triggered framework exploiting switching triggering conditions is proposed for FAHV to better balance system responses and energy reservation.2)For the first time,the issue of event-triggered control is studied for FAHV to avoid unnecessary communication resource consumption in the premise of competitive tracking accuracy,while the unreasonable energy and resources consumptions are extensive and inevitable in the current researches along the line of continuous sampling.4.Appointed time fault-tolerant control for FAHVTo realize a reliable trajectory tracking for FAHV even when input saturation and actuator faults occur,meanwhile removing the tedious parameter tuning process demanded in current prescribed performance control techniques for pursuing expected convergence time,herein,an appointed time fault-tolerant control is investigated for FAHV,whose innovations can be condensed as follows:1)An appointed-time prescribed performance control(APPC)is firstly presented to make the FAHV tracking errors converge to predefined residual sets without transgressing a pre-appointed time,while the current PPC results for FAHV can only achieve an exponential decaying rate,whose convergence time cannot be prespecified exactly prior to the implementation.2)To make the system dynamics stable when the input saturation occurs,auxiliary systems are employed to automatically modify the predefined reference,such that the influence of input saturation originating from the initial system deviation and lumped effect can be released.