To improve the robustness of visual tracking in complex environments such as: cluttered backgrounds, partial occlusions, similar distraction and pose variations, a novel tracking method based on adaptive fusion and pa...To improve the robustness of visual tracking in complex environments such as: cluttered backgrounds, partial occlusions, similar distraction and pose variations, a novel tracking method based on adaptive fusion and particle filter is proposed in this paper. In this method, the image color and shape cues are adaptively fused to represent the target observation; fuzzy logic is applied to dynamically adjust each cue weight according to its associated reliability in the past frame; particle filter is adopted to deal with non-linear and non-Gaussian problems in visual tracking. The method is demonstrated to be robust to illumination changes, pose variations, partial occlusions, cluttered backgrounds and camera motion for a test image sequence.展开更多
In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state constraints.Due to the coexist of the non-affine structure and ful...In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state constraints.Due to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered system.According to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be applied.Then,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear terms.The presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to zero.Meanwhile,it is shown that the constraint requirement on the system will not be violated during the operation.Finally,two simulation examples are provided to show the effectiveness of the proposed control scheme.展开更多
In this paper,the authors tackle a fixed-time average-tracking problem for multi-agent systems which do not require velocity measurements and are affected by external mismatched and matched disturbances.The objective ...In this paper,the authors tackle a fixed-time average-tracking problem for multi-agent systems which do not require velocity measurements and are affected by external mismatched and matched disturbances.The objective requires the considered agents with second-order dynamics to follow the average value of several time-varying reference signals,each of which is acquired by only one agent.First of all,the average value is estimated by using a novel distributed average estimator in a fixed time.Second,an original observer is created to provide estimated values in a fixed time for external mismatched and matched disturbances as well as unmeasured velocities of agents.Then,the authors propose a novel fixed-time anti-disturbance average-tracking protocol with the aid of the observer and a sliding mode surface.In the end,the feasibility of theoretical analysis is illustrated by some simulation experiments.展开更多
While different species in nature have safely solved the problem of navigation in a dynamic environment, this remains a challenging task for researchers around the world. The paper addresses the problem of autonomous ...While different species in nature have safely solved the problem of navigation in a dynamic environment, this remains a challenging task for researchers around the world. The paper addresses the problem of autonomous navigation in an unknown dynamic environment for a single and a group of three wheeled omnidirectional mobile robots(TWOMRs). The robot has to track a dynamic target while avoiding dynamic obstacles and dynamic walls in an unknown and very dense environment. It adopts a behavior-based controller that consists of four behaviors: "target tracking", "obstacle avoidance", "dynamic wall following" and "avoid robots". The paper considers the problem of kinematic saturation. In addition, it introduces a strategy for predicting the velocity of dynamic obstacles based on two successive measurements of the ultrasonic sensors to calculate the velocity of the obstacle expressed in the sensor frame. Furthermore, the paper proposes a strategy to deal with dynamic walls even when they have U-like or V-like shapes. The approach can also deal with the formation control of a group of robots based on the leader-follower structure and the behavior-based control, where the robots have to get together and maintain a given formation while navigating toward the target, avoiding obstacles and walls in a dynamic environment. The effectiveness of the proposed approaches is demonstrated via simulation.展开更多
An impulsive control scheme is proposed to investigate the tracking synchronization of ring and inline networked Lagrangian systems.Given a time-varying target trajectory,some algebraic synchronization criteria are de...An impulsive control scheme is proposed to investigate the tracking synchronization of ring and inline networked Lagrangian systems.Given a time-varying target trajectory,some algebraic synchronization criteria are derived to make the networked Lagrangian systems synchronize to the target trajectory.A distinctive feature of the proposed work is that the impulsive control scheme is used to investigate the highly nonlinear Lagrangian systems.By the impulsive control,each agent described by the Lagrangian system instantaneously interacts with its neighbors only at some discrete moments.Furthermore,the proposed control strategy requires only local coupling feedback for global convergence.As a direct application of the obtained theoretical results,the tracking synchronization of multiple 3-DOF mobile robots is discussed in detail and simulated.Simulation results verify the effectiveness of the proposed control strategy.展开更多
基金This work was jointly supported by the National Natural Science Foundation of China (No. 60375008)China PH.D Discipline Special Foundation (No. 20020248029)China Aviation Science Foundation (No. 02D57003)Aerospace Supporting Technology Foundation (No.2003-1.3 02), EXPO Technologies Special Project of National Key Technologies R&D Programme (No. 004BA908B07)Shanghai Key Technologies Preresearch Project (No. 035115009).
文摘To improve the robustness of visual tracking in complex environments such as: cluttered backgrounds, partial occlusions, similar distraction and pose variations, a novel tracking method based on adaptive fusion and particle filter is proposed in this paper. In this method, the image color and shape cues are adaptively fused to represent the target observation; fuzzy logic is applied to dynamically adjust each cue weight according to its associated reliability in the past frame; particle filter is adopted to deal with non-linear and non-Gaussian problems in visual tracking. The method is demonstrated to be robust to illumination changes, pose variations, partial occlusions, cluttered backgrounds and camera motion for a test image sequence.
基金supported in part by the National Natural Science Foundation of China under Grant No.62303278in part by the Taishan Scholar Project of Shandong Province of China under Grant No.tsqn201909078。
文摘In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state constraints.Due to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered system.According to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be applied.Then,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear terms.The presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to zero.Meanwhile,it is shown that the constraint requirement on the system will not be violated during the operation.Finally,two simulation examples are provided to show the effectiveness of the proposed control scheme.
基金supported by the National Natural Science Foundation of China under Grant Nos.61973139,61973082 and 61473138the Fundamental Research Funds for the Central Universities under Grant No.JUSRP22014。
文摘In this paper,the authors tackle a fixed-time average-tracking problem for multi-agent systems which do not require velocity measurements and are affected by external mismatched and matched disturbances.The objective requires the considered agents with second-order dynamics to follow the average value of several time-varying reference signals,each of which is acquired by only one agent.First of all,the average value is estimated by using a novel distributed average estimator in a fixed time.Second,an original observer is created to provide estimated values in a fixed time for external mismatched and matched disturbances as well as unmeasured velocities of agents.Then,the authors propose a novel fixed-time anti-disturbance average-tracking protocol with the aid of the observer and a sliding mode surface.In the end,the feasibility of theoretical analysis is illustrated by some simulation experiments.
文摘While different species in nature have safely solved the problem of navigation in a dynamic environment, this remains a challenging task for researchers around the world. The paper addresses the problem of autonomous navigation in an unknown dynamic environment for a single and a group of three wheeled omnidirectional mobile robots(TWOMRs). The robot has to track a dynamic target while avoiding dynamic obstacles and dynamic walls in an unknown and very dense environment. It adopts a behavior-based controller that consists of four behaviors: "target tracking", "obstacle avoidance", "dynamic wall following" and "avoid robots". The paper considers the problem of kinematic saturation. In addition, it introduces a strategy for predicting the velocity of dynamic obstacles based on two successive measurements of the ultrasonic sensors to calculate the velocity of the obstacle expressed in the sensor frame. Furthermore, the paper proposes a strategy to deal with dynamic walls even when they have U-like or V-like shapes. The approach can also deal with the formation control of a group of robots based on the leader-follower structure and the behavior-based control, where the robots have to get together and maintain a given formation while navigating toward the target, avoiding obstacles and walls in a dynamic environment. The effectiveness of the proposed approaches is demonstrated via simulation.
基金supported by the National Natural Science Foundation of China under Grant No.61603174the 2015th Training Programme Foundation for Excellent Youth Researching Talents of Fujian’s Universities under Grant No.2001B11540
文摘An impulsive control scheme is proposed to investigate the tracking synchronization of ring and inline networked Lagrangian systems.Given a time-varying target trajectory,some algebraic synchronization criteria are derived to make the networked Lagrangian systems synchronize to the target trajectory.A distinctive feature of the proposed work is that the impulsive control scheme is used to investigate the highly nonlinear Lagrangian systems.By the impulsive control,each agent described by the Lagrangian system instantaneously interacts with its neighbors only at some discrete moments.Furthermore,the proposed control strategy requires only local coupling feedback for global convergence.As a direct application of the obtained theoretical results,the tracking synchronization of multiple 3-DOF mobile robots is discussed in detail and simulated.Simulation results verify the effectiveness of the proposed control strategy.
