Digital image correlationmethod is awidely used non-contact deformationmeasurement method.However,in lowtemperature environment the airships stay in,the camera needs to be protected by thermal insulation device,the op...Digital image correlationmethod is awidely used non-contact deformationmeasurement method.However,in lowtemperature environment the airships stay in,the camera needs to be protected by thermal insulation device,the optical glass of which introduces the refraction error to photogrammetry technology.To solve the influence of refraction error on the deformation measurement accuracy of digital image correlation method,the displacement deviation caused by refraction is theoretically deduced to obtain the deviation model based on the analysis of refraction light path and digital image correlation method.Moreover,the corresponding refraction error correction based on deformation function is proposed.Through the contrast experiment,it is found that the refraction offset error model is consistent with the actual displacement deviation.The digital image correlation method based on the refraction error correction proposed in this paper can effectively depress the refraction effect of glass,reduce the measurement error and improve the deformation measurement accuracy.展开更多
The stratospheric airship uses the electric thrusters composed of motors and large diameter propellers to generate the forward thrust and heading manipulation torque.As the actuators of flight control,electric thruste...The stratospheric airship uses the electric thrusters composed of motors and large diameter propellers to generate the forward thrust and heading manipulation torque.As the actuators of flight control,electric thrusters have an important impact on the station-keeping and flight-control performance.Due to the high-altitude environment and low-speed flight of big volumetric stratospheric airships,the operating of electric thrusters is significantly different from that of electric aircraft,whichmakes the analysis and modeling of electric thrusters difficult.In this paper,the characteristics of motors and propellers for stratospheric airship is analyzed at first.Then,the propeller and motormodel expressions are summarized respectively,mainly concentrating on the relationship between torque,thrust,advance speed and rotational speed.Benefited from the methods in the field of marine propellers,a quantitative characterization method for the interaction between propeller and airship hull is introduced.Through themechanical motion equation of the motor,the dynamic matching model between themotor output electromagnetic torque and the propeller load torque is described.An example is used to illustrate the modeling process.Finally,some of the challenging issues in engineering practice are discussed.展开更多
Aiming at the problems of control consumption,obstacle avoidance and topology change of multi-UAV formation control,a variable topology optimal obstacle avoidance consensus formation control method for multi-UAV syste...Aiming at the problems of control consumption,obstacle avoidance and topology change of multi-UAV formation control,a variable topology optimal obstacle avoidance consensus formation control method for multi-UAV system is proposed in this paper.First,a nonlinear model of the fixed-wing UAV is established,which is simplified to a second-order integral model by feedback linearization method.Then,a basic consensus control protocol is designed based on graph theory for obstacle-free formation control.On this basis,considering control consumption and topology change comprehensively,a variable topology optimal consensus algorithm is proposed to achieve the consensus of position and velocity information with minimum control consumption.In addition,considering the improved artificial potential field function in the obstacle environment,the optimal consensus algorithm of obstacle avoidance is obtained.Then,the stability of the proposed method is proved by the Lyapunov stability theory.Finally,the effectiveness of the proposed method is verified by numerical simulation,and the multi-UAV system can achieve the desired flight formation with the minimum control cost under the condition of variable topology and obstacles.展开更多
In the future,the stratospheric airship will be used to accomplish the continuous cruising mission in the widely distributed area.To solve the trajectory planning problem of a single airship continuously cruising mult...In the future,the stratospheric airship will be used to accomplish the continuous cruising mission in the widely distributed area.To solve the trajectory planning problem of a single airship continuously cruising multi-target regions,a global trajectory planning algorithm with the minimum energy consumption is proposed under the assumption of constant horizontal wind and cruising altitude.First,the singular perturbation method is used to plan the trajectory of the airship with minimum energy consumption in the long-distance straight cruise phase between each two target regions.This method determines the optimal yaw angle and cruising speed of the airship.Then,quadratic programming is used to solve the trajectory of the airship cruising in the target region by considering the smoothness and continuity of the airship's flight,the requirements of cruising time,and the constraints of speed and acceleration.Finally,the trajectory is optimized by considering the yaw rate constraint to strengthen the dynamic feasibility.Based on the above algorithms,we give a specific trajectory planning case in the last section.展开更多
In this paper,the formation control problem of a second-order unmanned aerial vehicle swarm system with switching topology and collision/obstacle avoidance has been studied.First,the linear consensus protocol for form...In this paper,the formation control problem of a second-order unmanned aerial vehicle swarm system with switching topology and collision/obstacle avoidance has been studied.First,the linear consensus protocol for formation control with switching topology is designed using graph theory.The conditions for information consensus are given.Second,the problem of collision/obstacle avoidance is also considered.And the consensus protocol with switching topology and collision/obstacle avoidance is proposed.The improved artificial potential approach is applied to realize collision/obstacle avoidance,which can avoid potential fields falling into the local minimum.Third,system stability under the proposed protocol is proved using the Lyapunov theory.Finally,numerical simulations are presented to demonstrate the effectiveness of the proposed protocol.展开更多
基金funded by the National Natural Science Foundation of China(NSFC)(GrantNo.51205253)。
文摘Digital image correlationmethod is awidely used non-contact deformationmeasurement method.However,in lowtemperature environment the airships stay in,the camera needs to be protected by thermal insulation device,the optical glass of which introduces the refraction error to photogrammetry technology.To solve the influence of refraction error on the deformation measurement accuracy of digital image correlation method,the displacement deviation caused by refraction is theoretically deduced to obtain the deviation model based on the analysis of refraction light path and digital image correlation method.Moreover,the corresponding refraction error correction based on deformation function is proposed.Through the contrast experiment,it is found that the refraction offset error model is consistent with the actual displacement deviation.The digital image correlation method based on the refraction error correction proposed in this paper can effectively depress the refraction effect of glass,reduce the measurement error and improve the deformation measurement accuracy.
基金supported by the National Science Foundation of China(Grant numbers[62073216]and[51906141]).
文摘The stratospheric airship uses the electric thrusters composed of motors and large diameter propellers to generate the forward thrust and heading manipulation torque.As the actuators of flight control,electric thrusters have an important impact on the station-keeping and flight-control performance.Due to the high-altitude environment and low-speed flight of big volumetric stratospheric airships,the operating of electric thrusters is significantly different from that of electric aircraft,whichmakes the analysis and modeling of electric thrusters difficult.In this paper,the characteristics of motors and propellers for stratospheric airship is analyzed at first.Then,the propeller and motormodel expressions are summarized respectively,mainly concentrating on the relationship between torque,thrust,advance speed and rotational speed.Benefited from the methods in the field of marine propellers,a quantitative characterization method for the interaction between propeller and airship hull is introduced.Through themechanical motion equation of the motor,the dynamic matching model between themotor output electromagnetic torque and the propeller load torque is described.An example is used to illustrate the modeling process.Finally,some of the challenging issues in engineering practice are discussed.
基金funded by the National Natural Science Foundation of China(NSFC)(Grant number 62073216).
文摘Aiming at the problems of control consumption,obstacle avoidance and topology change of multi-UAV formation control,a variable topology optimal obstacle avoidance consensus formation control method for multi-UAV system is proposed in this paper.First,a nonlinear model of the fixed-wing UAV is established,which is simplified to a second-order integral model by feedback linearization method.Then,a basic consensus control protocol is designed based on graph theory for obstacle-free formation control.On this basis,considering control consumption and topology change comprehensively,a variable topology optimal consensus algorithm is proposed to achieve the consensus of position and velocity information with minimum control consumption.In addition,considering the improved artificial potential field function in the obstacle environment,the optimal consensus algorithm of obstacle avoidance is obtained.Then,the stability of the proposed method is proved by the Lyapunov stability theory.Finally,the effectiveness of the proposed method is verified by numerical simulation,and the multi-UAV system can achieve the desired flight formation with the minimum control cost under the condition of variable topology and obstacles.
基金supported by National Natural Science Foundation of China(Grant 62073216).
文摘In the future,the stratospheric airship will be used to accomplish the continuous cruising mission in the widely distributed area.To solve the trajectory planning problem of a single airship continuously cruising multi-target regions,a global trajectory planning algorithm with the minimum energy consumption is proposed under the assumption of constant horizontal wind and cruising altitude.First,the singular perturbation method is used to plan the trajectory of the airship with minimum energy consumption in the long-distance straight cruise phase between each two target regions.This method determines the optimal yaw angle and cruising speed of the airship.Then,quadratic programming is used to solve the trajectory of the airship cruising in the target region by considering the smoothness and continuity of the airship's flight,the requirements of cruising time,and the constraints of speed and acceleration.Finally,the trajectory is optimized by considering the yaw rate constraint to strengthen the dynamic feasibility.Based on the above algorithms,we give a specific trajectory planning case in the last section.
基金funded by the National Natural Science Foundation of China(NSFC)(Grant no.51906141).
文摘In this paper,the formation control problem of a second-order unmanned aerial vehicle swarm system with switching topology and collision/obstacle avoidance has been studied.First,the linear consensus protocol for formation control with switching topology is designed using graph theory.The conditions for information consensus are given.Second,the problem of collision/obstacle avoidance is also considered.And the consensus protocol with switching topology and collision/obstacle avoidance is proposed.The improved artificial potential approach is applied to realize collision/obstacle avoidance,which can avoid potential fields falling into the local minimum.Third,system stability under the proposed protocol is proved using the Lyapunov theory.Finally,numerical simulations are presented to demonstrate the effectiveness of the proposed protocol.
