Multirotor has been applied to many military and civilian mission scenarios. From the perspective of reliability, it is difficult to ensure that multirotors do not generate hardware and software failures or performanc...Multirotor has been applied to many military and civilian mission scenarios. From the perspective of reliability, it is difficult to ensure that multirotors do not generate hardware and software failures or performance anomalies during the flight process. These failures and anomalies may result in mission interruptions, crashes, and even threats to the lives and property of human beings.Thus, the study of flight reliability problems of multirotors is conductive to the development of the drone industry and has theoretical significance and engineering value. This paper proposes a reliable flight performance assessment method of multirotors based on an Interacting Multiple Model Particle Filter(IMMPF) algorithm and health degree as the performance indicator. First, the multirotor is modeled by the Stochastic Hybrid System(SHS) model, and the problem of reliable flight performance assessment is formulated. In order to solve the problem, the IMMPF algorithm is presented to estimate the real-time probability distribution of hybrid state of the established SHS-based multirotor model, since it can decrease estimation errors compared with the standard interacting multiple model algorithm based on extended Kalman filter. Then, the reliable flight performance is assessed with health degree based on the estimation result. Finally, a case study of a multirotor suffering from sensor anomalies is presented to validate the effectiveness of the proposed method.展开更多
A brief concept study of a modular research aircraft with potential applications to Mars exploration is conducted.Considered are dimensional and mass constraints of a launch vehicle payload compartment,mission radius ...A brief concept study of a modular research aircraft with potential applications to Mars exploration is conducted.Considered are dimensional and mass constraints of a launch vehicle payload compartment,mission radius extension applying ground mobility and overall flight envelope extension using fixed-wing aerodynamics.Also,some lessons learned from NASA Mars Ingenuity flights are considered and addressed with few solutions.The modular system includes a fixed-wing design along with a number of smaller autonomous quadcopter UAVs,encapsulated inside a geodesic spherical support through a gimbal mechanism for ground mobility.Analyzed is the feasibility of allocating to these mini drones both scout and mapping tasks of complex terrain such as crater walls,canyons and cave systems that might hold key insights into the planet's geologic history.Once docked with the mothership fixed wing,the mini drones serve as a distributed propulsion system,for vertical take-off and landing and control,completely replacing control surfaces on the flying wing itself,its engine and landing gear.CFD and structural simulations have demonstrated the flight-ability in Mars conditions of a flying wing design along with scout drone prototypes with a pentagon-hexagon geodesic shell.Also demonstrated is the great flexibility of the suggested modular approach for various research applications and mission profiles on Mars and other planets or moons,improving overall reliability and mission radius.展开更多
Web-like obstacles,such as safety nets,represent a unique hazard for drones,and especially UAVs(Unmanned Aerial Vehicles).Fencing and netting are particularly difficult to distinguish from the background using either ...Web-like obstacles,such as safety nets,represent a unique hazard for drones,and especially UAVs(Unmanned Aerial Vehicles).Fencing and netting are particularly difficult to distinguish from the background using either computer vision,lidar and sonar.In contrast,animals such as flying insects may detect these web-like obstacles using Optic Flow(OF),and more precisely motion parallax.A netting-avoidance solution was proposed using a OF-based detection method.The netting detection method was based on a signature defined by the shape of the OF magnitude across the visual field.We established that the OF shape depends on the orientation of the netting in relation to the hexarotor’s movement.This paper demonstrates netting detection in real-world experiments,according to any direction flight made by the UAV along the net.The proposed NOWA method(which stands for Netting Optical floW-based distinction Algorithm)separates the OF signatures belonging to these different surfaces-netting or background-whatever their orientations.By extracting the OF signatures of these different surfaces and separating them,the proposed visual method can estimate their relative locations and orientations.In a robotic simulations,the multirotor explores and navigates automatically using this netting detection method,using saccades to avoid obstacles.In the simulations,these saccades are also used to simplify netting detection by orienting itself systematically parallel to these planes,a behavior reminiscent of flying insects.展开更多
An aircraft quadrotor is a complex control system that allows for great flexibility in flight.Controlling multirotor aerial systems such as quadrotors is complex because the variables involved are not always available...An aircraft quadrotor is a complex control system that allows for great flexibility in flight.Controlling multirotor aerial systems such as quadrotors is complex because the variables involved are not always available,known,and accurate.The inclusion of payload changes the dynamic characteristics of the aircraft,making it necessary to adapt the control system for this situation.Among the various control methods that have been investigated,proportional-integralderivative(PID)control offers good results and simplicity of application;however,achieving stability and high performance is challenging,with the most critical task being tuning the controller gains.The Ziegler-Nichols(ZN)theory was used to tune the controller gains for pitch and roll attitude command;however,the performance results were not satisfactory.The response of this system was refined,resulting in an improvement in the reference tracking and the rejection of disturbances.This particular refinement was applied to the quadrotor,and via a reverse calculation,the parameters that allow the tuning of PID gains were obtained,based on ZN.The particularization of the ZN theory applied to a quadrotor with and without a load(termed ZNAQ and ZNAQL,respectively)is proposed and results in a significant improvement in the control system response performance(up to 75%),demonstrating that ZNAQ and ZNAQL are valid for tuning the controller PID gains and are more efficient than the original ZN theory approach.展开更多
There is a growing body of research indicating that drones can disturb animals.However,it is usu-ally unclear whether the disturbance is due to visual or auditory cues.Here,we examined the effect of drone flights on t...There is a growing body of research indicating that drones can disturb animals.However,it is usu-ally unclear whether the disturbance is due to visual or auditory cues.Here,we examined the effect of drone flights on the behavior of great dusky swifts Cypseloides senex and white collared swifts Streptoprocne zonaris in 2 breeding sites where drone noise was obscured by environmental noise from waterfalls and any disturbance must be largely visual.We performed 12 experimental flights with a multirotor drone at different vertical,horizontal,and diagonal distances from the colonies.From all flights,17%caused<1%of birds to temporarily a bandon the breeding site,50%caused half to abandon,and 33%caused more than half to abandon.We found that the diagonal distance explained 98.9%of the variability of the disturbance percentage and while at distances>50 m the disturbance percentage does not exceed 20%,at<40 m the disturbance percentage increase to>60%.We recommend that flights with a multirotor drone during the breeding period should be con-ducted at a distance of>50 m and that recreational flights should be discouraged or conducted at larger distances(e.g.100 m)in nesting birds areas such as waterfalls,canyons,and caves.展开更多
Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of ...Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors.To reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this study.First,the fast prediction method is used to estimate the global noise of the multirotor with different configurations online.Meanwhile,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation.Then,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited.Next,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain characteristics.Finally,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results.The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB.Moreover,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control.展开更多
Cooperation among multiple unmanned vehicles is an intensely challenging topic from a theoretical and practical standpoint, with far reaching indications in scientific and commercial mission scenarios. The difficulty ...Cooperation among multiple unmanned vehicles is an intensely challenging topic from a theoretical and practical standpoint, with far reaching indications in scientific and commercial mission scenarios. The difficulty of time coordination for a rapid of multirotor UAVs includes predefined spatial paths according to mission necessities. With the solution proposed, cooperative control is accomplished in the presence of time-varying communication networks, as well as stringent temporal constraints, such as concurrent arrival at the desired final locations. The proposed explanation solves the time-coordination problem under the acceptance that the trajectory-genera- tion and the path-following algorithms meeting convinced cohesion conditions are given. Communication is processed in unpredictable paths by the use of path following and directed communication graph. Dijik-Primbert algorithm for finding the shortest collision free paths is used to avoid and detect collision/congestion in unpredictable paths. Without collision detection, it doesn’t seem agreeable to have collision avoidance because there wouldn’t be everything to avoid. Dijikloyd algorithm is used for finding shortest paths in a weighted directed graph with positive and negative edges. Primloyd algorithm is used for finding shortest paths in a weighted undirected graph for conquering the complexity in matrix coding. In case of conges- tion or collision then the whole network is learned about it to all the communica- tors. Hence, communication is taken place in an unpredictable path in a secured manner.展开更多
基金co-supported by the Beijing Natural Science Foundation of China (No. 4194074)the National Key R&D Program of China (No. 2017YFC1600605)+1 种基金the Shandong Provincial Natural Science Foundation of China (No. ZR2018BF016)the Beijing Municipal Education Commission Research Program-General Project of China (No. KM201910011011)
文摘Multirotor has been applied to many military and civilian mission scenarios. From the perspective of reliability, it is difficult to ensure that multirotors do not generate hardware and software failures or performance anomalies during the flight process. These failures and anomalies may result in mission interruptions, crashes, and even threats to the lives and property of human beings.Thus, the study of flight reliability problems of multirotors is conductive to the development of the drone industry and has theoretical significance and engineering value. This paper proposes a reliable flight performance assessment method of multirotors based on an Interacting Multiple Model Particle Filter(IMMPF) algorithm and health degree as the performance indicator. First, the multirotor is modeled by the Stochastic Hybrid System(SHS) model, and the problem of reliable flight performance assessment is formulated. In order to solve the problem, the IMMPF algorithm is presented to estimate the real-time probability distribution of hybrid state of the established SHS-based multirotor model, since it can decrease estimation errors compared with the standard interacting multiple model algorithm based on extended Kalman filter. Then, the reliable flight performance is assessed with health degree based on the estimation result. Finally, a case study of a multirotor suffering from sensor anomalies is presented to validate the effectiveness of the proposed method.
基金funded by the Russian Science Foundation(No.22–49-02047)。
文摘A brief concept study of a modular research aircraft with potential applications to Mars exploration is conducted.Considered are dimensional and mass constraints of a launch vehicle payload compartment,mission radius extension applying ground mobility and overall flight envelope extension using fixed-wing aerodynamics.Also,some lessons learned from NASA Mars Ingenuity flights are considered and addressed with few solutions.The modular system includes a fixed-wing design along with a number of smaller autonomous quadcopter UAVs,encapsulated inside a geodesic spherical support through a gimbal mechanism for ground mobility.Analyzed is the feasibility of allocating to these mini drones both scout and mapping tasks of complex terrain such as crater walls,canyons and cave systems that might hold key insights into the planet's geologic history.Once docked with the mothership fixed wing,the mini drones serve as a distributed propulsion system,for vertical take-off and landing and control,completely replacing control surfaces on the flying wing itself,its engine and landing gear.CFD and structural simulations have demonstrated the flight-ability in Mars conditions of a flying wing design along with scout drone prototypes with a pentagon-hexagon geodesic shell.Also demonstrated is the great flexibility of the suggested modular approach for various research applications and mission profiles on Mars and other planets or moons,improving overall reliability and mission radius.
基金The participation of X.D.in this research was made possible by the joint PhD grant from the Agence Innovation Défense(AID)and Aix-Marseille UniversityFinancial support for the running costs was provided via a ProxiLearn project grant(ANR-19-ASTR-0009)to F.R.+2 种基金via SpotReturn project grant(ANR-21-ASRO-0001-02)to T.R.and F.R.from the ANR(Astrid Program)X.D.and F.R.were also supported by Aix Marseille University and the CNRS(Life Science,Information Science,and Engineering and Science&technology Institutes)The facilities for the experimental tests has been mainly provided by ROBOTEX 2.0(Grants ROBOTEX ANR-10-EQPX-44-01 and TIRREX ANR-21-ESRE-0015).
文摘Web-like obstacles,such as safety nets,represent a unique hazard for drones,and especially UAVs(Unmanned Aerial Vehicles).Fencing and netting are particularly difficult to distinguish from the background using either computer vision,lidar and sonar.In contrast,animals such as flying insects may detect these web-like obstacles using Optic Flow(OF),and more precisely motion parallax.A netting-avoidance solution was proposed using a OF-based detection method.The netting detection method was based on a signature defined by the shape of the OF magnitude across the visual field.We established that the OF shape depends on the orientation of the netting in relation to the hexarotor’s movement.This paper demonstrates netting detection in real-world experiments,according to any direction flight made by the UAV along the net.The proposed NOWA method(which stands for Netting Optical floW-based distinction Algorithm)separates the OF signatures belonging to these different surfaces-netting or background-whatever their orientations.By extracting the OF signatures of these different surfaces and separating them,the proposed visual method can estimate their relative locations and orientations.In a robotic simulations,the multirotor explores and navigates automatically using this netting detection method,using saccades to avoid obstacles.In the simulations,these saccades are also used to simplify netting detection by orienting itself systematically parallel to these planes,a behavior reminiscent of flying insects.
基金the National Natural Science Foundation of China(Nos.42130810,42004065,42074165)the Key Research and Development Program of Hunan Province,China(No.2020SK2058).
文摘An aircraft quadrotor is a complex control system that allows for great flexibility in flight.Controlling multirotor aerial systems such as quadrotors is complex because the variables involved are not always available,known,and accurate.The inclusion of payload changes the dynamic characteristics of the aircraft,making it necessary to adapt the control system for this situation.Among the various control methods that have been investigated,proportional-integralderivative(PID)control offers good results and simplicity of application;however,achieving stability and high performance is challenging,with the most critical task being tuning the controller gains.The Ziegler-Nichols(ZN)theory was used to tune the controller gains for pitch and roll attitude command;however,the performance results were not satisfactory.The response of this system was refined,resulting in an improvement in the reference tracking and the rejection of disturbances.This particular refinement was applied to the quadrotor,and via a reverse calculation,the parameters that allow the tuning of PID gains were obtained,based on ZN.The particularization of the ZN theory applied to a quadrotor with and without a load(termed ZNAQ and ZNAQL,respectively)is proposed and results in a significant improvement in the control system response performance(up to 75%),demonstrating that ZNAQ and ZNAQL are valid for tuning the controller PID gains and are more efficient than the original ZN theory approach.
文摘There is a growing body of research indicating that drones can disturb animals.However,it is usu-ally unclear whether the disturbance is due to visual or auditory cues.Here,we examined the effect of drone flights on the behavior of great dusky swifts Cypseloides senex and white collared swifts Streptoprocne zonaris in 2 breeding sites where drone noise was obscured by environmental noise from waterfalls and any disturbance must be largely visual.We performed 12 experimental flights with a multirotor drone at different vertical,horizontal,and diagonal distances from the colonies.From all flights,17%caused<1%of birds to temporarily a bandon the breeding site,50%caused half to abandon,and 33%caused more than half to abandon.We found that the diagonal distance explained 98.9%of the variability of the disturbance percentage and while at distances>50 m the disturbance percentage does not exceed 20%,at<40 m the disturbance percentage increase to>60%.We recommend that flights with a multirotor drone during the breeding period should be con-ducted at a distance of>50 m and that recreational flights should be discouraged or conducted at larger distances(e.g.100 m)in nesting birds areas such as waterfalls,canyons,and caves.
文摘Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors.To reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this study.First,the fast prediction method is used to estimate the global noise of the multirotor with different configurations online.Meanwhile,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation.Then,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited.Next,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain characteristics.Finally,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results.The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB.Moreover,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control.
文摘Cooperation among multiple unmanned vehicles is an intensely challenging topic from a theoretical and practical standpoint, with far reaching indications in scientific and commercial mission scenarios. The difficulty of time coordination for a rapid of multirotor UAVs includes predefined spatial paths according to mission necessities. With the solution proposed, cooperative control is accomplished in the presence of time-varying communication networks, as well as stringent temporal constraints, such as concurrent arrival at the desired final locations. The proposed explanation solves the time-coordination problem under the acceptance that the trajectory-genera- tion and the path-following algorithms meeting convinced cohesion conditions are given. Communication is processed in unpredictable paths by the use of path following and directed communication graph. Dijik-Primbert algorithm for finding the shortest collision free paths is used to avoid and detect collision/congestion in unpredictable paths. Without collision detection, it doesn’t seem agreeable to have collision avoidance because there wouldn’t be everything to avoid. Dijikloyd algorithm is used for finding shortest paths in a weighted directed graph with positive and negative edges. Primloyd algorithm is used for finding shortest paths in a weighted undirected graph for conquering the complexity in matrix coding. In case of conges- tion or collision then the whole network is learned about it to all the communica- tors. Hence, communication is taken place in an unpredictable path in a secured manner.
