In this paper, a bearing-based three-dimensional self-localization and distributed circumnavigation with connectivity preservation and collision avoidance are investigated for a group of quadrotor-type unmanned aerial...In this paper, a bearing-based three-dimensional self-localization and distributed circumnavigation with connectivity preservation and collision avoidance are investigated for a group of quadrotor-type unmanned aerial vehicles (UAVs). A leader–follower structure is adopted, wherein the leader moves with reference dynamics (a target). Different from the existing approaches that necessitate full knowledge of the time-varying reference trajectory, in this paper, it is assumed that only some vehicles (at least one) have access to the bearing relative to the target, and all other vehicles are equipped with sensors capable of measuring the bearings relative to neighboring vehicles. In this paper, a consensus estimator is proposed to estimate the global position for each vehicle using relative bearing measurements and an estimate of neighboring vehicles received from a direct communication network. Then, a continuous robust integral of the sign of the error (RISE) control approach is effectively integrated with the distributed vector field approach to ensure UAV formation orbiting around the moving target while avoiding obstacles and maintaining network links within available communication ranges. In contrast to the classical RISE control rule, a \(\tanh (\cdot )\) function is used instead of the \(\text {sgn}(\cdot )\) function to further decrease the high-gain feedback and to obtain a smoother control signal. Furthermore, by using the localized radial basis function (RBF) neural networks (NNs) in a cooperative way, deterministic learning theory is employed to accurately identify/learn model uncertainties resulting from the attitude dynamics. The convergence of the entire closed-loop system is illustrated using the Lyapunov theory and is shown to be uniformly ultimately bounded. Finally, numerical simulations show the effectiveness of the proposed approach.展开更多
This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premi...This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving target.Besides,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication traffic.Then,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular spacing.It is inferred from Lyapunov stability that all errors are demonstrated to be convergent.Simulations are offered to verify the utility of proposed protocol.展开更多
Zhang Bo is a legend in his own right:at the age of 52,he obtained his pilot’s license;at 54,he became the first Chinese citizen to circumnavigate the globe by air;and at 57,he completed his second round-the-world fl...Zhang Bo is a legend in his own right:at the age of 52,he obtained his pilot’s license;at 54,he became the first Chinese citizen to circumnavigate the globe by air;and at 57,he completed his second round-the-world flight.展开更多
Sacadura Cabral was one of the two Portuguese navigators that crossed by air the South Atlantic in the beginning of the 20<sup>th</sup> century. From 1901 to 1915 Sacadura was at Mozambique and Angola wher...Sacadura Cabral was one of the two Portuguese navigators that crossed by air the South Atlantic in the beginning of the 20<sup>th</sup> century. From 1901 to 1915 Sacadura was at Mozambique and Angola where he developed geodetic and geographical missions of the greatest importance for Portuguese interest at Africa. With the Great World War requirements as a Navy Officer with 34 years old he decided to serve Portugal at the Aviation. In 1915 he went to France and obtained its pilot license. In 1916 Sacadura returned to Portugal and begun its instructor pilot career. He developed the “path corrector” which he created to compensate the drift caused by wind. In 1922 Sacadura made the First Air cross from Europe to South Atlantic. In 1923 he proposes himself to make an attempt to the First Air Circumnavigation Journey. He developed all its possible efforts to initiate this journey in March of 1924;however some delays had forced him to postpone the journey. Sacadura received important official medals and prizes, including the PhD Honoris Causa from the Universities of Lisbon and Oporto. In 1924 he died before he could carry out its Circumnavigation Air Journey.展开更多
Gago Coutinho, jointly with another Portuguese aerial navigator, managed to perform the First Flight from Europe to the South Atlantic in 1922, a Journey exclusively guided by internal means of navigation. Despite Cou...Gago Coutinho, jointly with another Portuguese aerial navigator, managed to perform the First Flight from Europe to the South Atlantic in 1922, a Journey exclusively guided by internal means of navigation. Despite Coutinho being a person with multi-purpose activity on several areas of knowledge, he became known and glorified in the World in 1922, as an air navigator, a position that he achieved due to an aerial navigation device that he also had invented. Coutinho developed a new sextant model that could be used to measure the altitude of a star (when flying overseas) without the need of the sea horizon. This new device was called precision sextant and was provided with an artificial horizon line defined with the help of a water bubble. Due to his knowledge of Navigation, Astronomy, Geography and Mathematics, Coutinho received from the Portuguese King D. Carlos I, several assignments at Africa and Asia. Gago Coutinho received several important official medals and prizes, including the Ph.D. Honoris Causa from the Universities of Lisbon and Oporto and authored several scientific publications. Coutinho received the distinct position of Admiral of the Portuguese Navy in 1958 and died in the following year.展开更多
In this paper,a novel formation control strategy is proposed to address the target tracking and circumnavigating problem of multi-UAV formation.First,two sets of definitions,space angle definition and space vector def...In this paper,a novel formation control strategy is proposed to address the target tracking and circumnavigating problem of multi-UAV formation.First,two sets of definitions,space angle definition and space vector definition,are presented in order to describe the flight state and construct the desired relative velocity.Then,the relative kinematic model between the UAV and the moving target is established.The distributed control law is constructed by using dynamic feedback linearization so as to realize the tracking and circumnavigating control with the desired velocity,circing radius and relative angular spacing.Next,the exponential stability of the closed-loop system is further guaranteed by properly choosing some corresponding parameters based on the Lyapunov method.Finally,the numerical simulation is caried out to verify the effectiveness of the proposed control method.展开更多
文摘In this paper, a bearing-based three-dimensional self-localization and distributed circumnavigation with connectivity preservation and collision avoidance are investigated for a group of quadrotor-type unmanned aerial vehicles (UAVs). A leader–follower structure is adopted, wherein the leader moves with reference dynamics (a target). Different from the existing approaches that necessitate full knowledge of the time-varying reference trajectory, in this paper, it is assumed that only some vehicles (at least one) have access to the bearing relative to the target, and all other vehicles are equipped with sensors capable of measuring the bearings relative to neighboring vehicles. In this paper, a consensus estimator is proposed to estimate the global position for each vehicle using relative bearing measurements and an estimate of neighboring vehicles received from a direct communication network. Then, a continuous robust integral of the sign of the error (RISE) control approach is effectively integrated with the distributed vector field approach to ensure UAV formation orbiting around the moving target while avoiding obstacles and maintaining network links within available communication ranges. In contrast to the classical RISE control rule, a \(\tanh (\cdot )\) function is used instead of the \(\text {sgn}(\cdot )\) function to further decrease the high-gain feedback and to obtain a smoother control signal. Furthermore, by using the localized radial basis function (RBF) neural networks (NNs) in a cooperative way, deterministic learning theory is employed to accurately identify/learn model uncertainties resulting from the attitude dynamics. The convergence of the entire closed-loop system is illustrated using the Lyapunov theory and is shown to be uniformly ultimately bounded. Finally, numerical simulations show the effectiveness of the proposed approach.
基金supported in part by the National Natural Science Foundation of China under Grant Nos.62173312,61922037,61873115,and 61803348in part by the National Major Scientific Instruments Development Project under Grant 61927807+6 种基金in part by the State Key Laboratory of Deep Buried Target Damage under Grant No.DXMBJJ2019-02in part by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi under Grant 2020L0266in part by the Shanxi Province Science Foundation for Youths under Grant No.201701D221123in part by the Youth Academic North University of China under Grant No.QX201803in part by the Program for the Innovative Talents of Higher Education Institutions of Shanxiin part by the Shanxi“1331Project”Key Subjects Construction under Grant 1331KSCin part by the Supported by Shanxi Province Science Foundation for Excellent Youths。
文摘This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target.By defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving target.Besides,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication traffic.Then,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular spacing.It is inferred from Lyapunov stability that all errors are demonstrated to be convergent.Simulations are offered to verify the utility of proposed protocol.
文摘Zhang Bo is a legend in his own right:at the age of 52,he obtained his pilot’s license;at 54,he became the first Chinese citizen to circumnavigate the globe by air;and at 57,he completed his second round-the-world flight.
文摘Sacadura Cabral was one of the two Portuguese navigators that crossed by air the South Atlantic in the beginning of the 20<sup>th</sup> century. From 1901 to 1915 Sacadura was at Mozambique and Angola where he developed geodetic and geographical missions of the greatest importance for Portuguese interest at Africa. With the Great World War requirements as a Navy Officer with 34 years old he decided to serve Portugal at the Aviation. In 1915 he went to France and obtained its pilot license. In 1916 Sacadura returned to Portugal and begun its instructor pilot career. He developed the “path corrector” which he created to compensate the drift caused by wind. In 1922 Sacadura made the First Air cross from Europe to South Atlantic. In 1923 he proposes himself to make an attempt to the First Air Circumnavigation Journey. He developed all its possible efforts to initiate this journey in March of 1924;however some delays had forced him to postpone the journey. Sacadura received important official medals and prizes, including the PhD Honoris Causa from the Universities of Lisbon and Oporto. In 1924 he died before he could carry out its Circumnavigation Air Journey.
文摘Gago Coutinho, jointly with another Portuguese aerial navigator, managed to perform the First Flight from Europe to the South Atlantic in 1922, a Journey exclusively guided by internal means of navigation. Despite Coutinho being a person with multi-purpose activity on several areas of knowledge, he became known and glorified in the World in 1922, as an air navigator, a position that he achieved due to an aerial navigation device that he also had invented. Coutinho developed a new sextant model that could be used to measure the altitude of a star (when flying overseas) without the need of the sea horizon. This new device was called precision sextant and was provided with an artificial horizon line defined with the help of a water bubble. Due to his knowledge of Navigation, Astronomy, Geography and Mathematics, Coutinho received from the Portuguese King D. Carlos I, several assignments at Africa and Asia. Gago Coutinho received several important official medals and prizes, including the Ph.D. Honoris Causa from the Universities of Lisbon and Oporto and authored several scientific publications. Coutinho received the distinct position of Admiral of the Portuguese Navy in 1958 and died in the following year.
基金supported in part by the National Natural Science Foundation of China(61703081,62173082)the Liaoning Joint Fund of National Natural Science Foundation of China(U1908217)+2 种基金the Liaoning Revitalization Talents Program(XLYC1801005)Natural Science Foundation of Liaoning Province(20170520113)and the Fundamental Research Funds for the Central Universities(N2004016).
文摘In this paper,a novel formation control strategy is proposed to address the target tracking and circumnavigating problem of multi-UAV formation.First,two sets of definitions,space angle definition and space vector definition,are presented in order to describe the flight state and construct the desired relative velocity.Then,the relative kinematic model between the UAV and the moving target is established.The distributed control law is constructed by using dynamic feedback linearization so as to realize the tracking and circumnavigating control with the desired velocity,circing radius and relative angular spacing.Next,the exponential stability of the closed-loop system is further guaranteed by properly choosing some corresponding parameters based on the Lyapunov method.Finally,the numerical simulation is caried out to verify the effectiveness of the proposed control method.
