In view of the complex marine environment of navigation,especially in the case of multiple static and dynamic obstacles,the traditional obstacle avoidance algorithms applied to unmanned surface vehicles(USV)are prone ...In view of the complex marine environment of navigation,especially in the case of multiple static and dynamic obstacles,the traditional obstacle avoidance algorithms applied to unmanned surface vehicles(USV)are prone to fall into the trap of local optimization.Therefore,this paper proposes an improved artificial potential field(APF)algorithm,which uses 5G communication technology to communicate between the USV and the control center.The algorithm introduces the USV discrimination mechanism to avoid the USV falling into local optimization when the USV encounter different obstacles in different scenarios.Considering the various scenarios between the USV and other dynamic obstacles such as vessels in the process of performing tasks,the algorithm introduces the concept of dynamic artificial potential field.For the multiple obstacles encountered in the process of USV sailing,based on the International Regulations for Preventing Collisions at Sea(COLREGS),the USV determines whether the next step will fall into local optimization through the discriminationmechanism.The local potential field of the USV will dynamically adjust,and the reverse virtual gravitational potential field will be added to prevent it from falling into the local optimization and avoid collisions.The objective function and cost function are designed at the same time,so that the USV can smoothly switch between the global path and the local obstacle avoidance.The simulation results show that the improved APF algorithm proposed in this paper can successfully avoid various obstacles in the complex marine environment,and take navigation time and economic cost into account.展开更多
Focusing on obstacle avoidance in three-dimensional space for unmanned aerial vehicle(UAV), the direct obstacle avoidance method in dynamic space based on three-dimensional velocity obstacle spherical cap is proposed,...Focusing on obstacle avoidance in three-dimensional space for unmanned aerial vehicle(UAV), the direct obstacle avoidance method in dynamic space based on three-dimensional velocity obstacle spherical cap is proposed, which quantifies the influence of threatening obstacles through velocity obstacle spherical cap parameters. In addition, the obstacle avoidance schemes of any point on the critical curve during the multi-obstacles avoidance are given. Through prediction, the insertion point for the obstacle avoidance can be obtained and the flight path can be replanned. Taking the Pythagorean Hodograph(PH) curve trajectory re-planning as an example, the three-dimensional direct obstacle avoidance method in dynamic space is tested. Simulation results show that the proposed method can realize the online obstacle avoidance trajectory re-planning, which increases the flexibility of obstacle avoidance greatly.展开更多
This paper presents a novel vision-based obstacle avoidance approach for the Autonomous Mobile Robot (AMR) with a Pan-Tilt-Zoom (PTZ) camera as its only sensing modality. The approach combines the morphological closin...This paper presents a novel vision-based obstacle avoidance approach for the Autonomous Mobile Robot (AMR) with a Pan-Tilt-Zoom (PTZ) camera as its only sensing modality. The approach combines the morphological closing operation based on Sobel Edge Detection Operation and the (μ-kσ) thresholding technique to detect obstacles to soften the various lighting and ground floor effects. Both the morphology method and thresholding technique are computationally simple. The processing speed of the algorithm is fast enough to avoid some active obstacles. In addition, this approach takes into account the history obstacle effects on the current state. Fuzzy logic is used to control the behaviors of AMR as it navigates in the environment. All behaviors run concurrently and generate motor response solely based on vision perception. A priority based on subsumption coordinator selects the most appropriate response to direct the AMR away from obstacles. Validation of the proposed approach is done on a Pioneer 1 mobile robot.展开更多
Rotorcraft in low-level flight is endangered by power lines or telephone wires. The development of automation tools that can detect obstacles in the flight path and warn the crew would significantly reduce pilot workl...Rotorcraft in low-level flight is endangered by power lines or telephone wires. The development of automation tools that can detect obstacles in the flight path and warn the crew would significantly reduce pilot workload and increase safety. Therefore, a cable detection radar system is developed The real-time dynamic imaging synchronizing with radar space scanning has been implemented in developed ladar system. The requirements of the flight mission to prevent "wire strike" are analyzed and estimated, the advantages and disadvantages of the millimeter wave system with the laser system are weighted The result shows that Laser system is the best suited for helicopter avoidance obstacle. In addition, several design gist of detecting wire radar that was used in the developed ladar system is proposed and the developed zero backlash imaging technology and several advanced warning function are described. The detailed results of system ground tests and the performances description are presented The ground test of the developed ladar system has demonstrated that the developed imaging ladar system performance can achieve and satisfy the requirements of the mission to prevent "wire strike".展开更多
由于果蔬采摘环境的不确定性和复杂性,机械臂在复杂环境中完成采摘,其路径规划需考虑实时避障。为实现采摘机械臂在不确定环境下安全采摘,提出一种改进RRT的动态避障算法,以提升机械臂在不确定采摘环境的适应性。针对基本快速扩展随机...由于果蔬采摘环境的不确定性和复杂性,机械臂在复杂环境中完成采摘,其路径规划需考虑实时避障。为实现采摘机械臂在不确定环境下安全采摘,提出一种改进RRT的动态避障算法,以提升机械臂在不确定采摘环境的适应性。针对基本快速扩展随机树算法(Rapidly-exploring Random Trees,RRT)在动态环境下迭代时间长、路径长、适应性差等问题,在RRT算法的基础上,引入目标导向策略,把终点以一定概率作为随机采样点的采样方向,提高算法的迭代效率;引入动态检测机制,对已完成规划的初始路径进行实时检测,使算法适应动态变化的环境。通过仿真分析改进RRT算法,结果表明:改进RRT算法的路径减少16%,迭代时间缩短86.5%;同时,动态检测机制使算法适应动态环境。展开更多
For the issue of nuclear radiation detection,this paper designs a remote control nuclear radiation detector which can trace a pre-determined route,avoid obstacles effectively,and can be controlled remotely by users wi...For the issue of nuclear radiation detection,this paper designs a remote control nuclear radiation detector which can trace a pre-determined route,avoid obstacles effectively,and can be controlled remotely by users wirelessly or through voice command.It can effectively replace manual probing due to convenience,flexibility and safety.The system mainly consists of a nuclear detection module,a voice control module,a route tracing module,an obstacle avoidance module,a data transmission module,storage and a display module,and a D.C.machine.An MSP430 microcontroller is used as a control chip to control the motor and the system uses infrared technology and ultrasonic sensors to achieve intelligent tracing and obstacle avoidance.Moreover,it applies a voice module and data transmission module to remotely controlling the device.The radiation data is shown on an LCD screen.展开更多
基金This work was supported by the Postdoctoral Fund of FDCT,Macao(Grant No.0003/2021/APD).Any opinions,findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the sponsor.
文摘In view of the complex marine environment of navigation,especially in the case of multiple static and dynamic obstacles,the traditional obstacle avoidance algorithms applied to unmanned surface vehicles(USV)are prone to fall into the trap of local optimization.Therefore,this paper proposes an improved artificial potential field(APF)algorithm,which uses 5G communication technology to communicate between the USV and the control center.The algorithm introduces the USV discrimination mechanism to avoid the USV falling into local optimization when the USV encounter different obstacles in different scenarios.Considering the various scenarios between the USV and other dynamic obstacles such as vessels in the process of performing tasks,the algorithm introduces the concept of dynamic artificial potential field.For the multiple obstacles encountered in the process of USV sailing,based on the International Regulations for Preventing Collisions at Sea(COLREGS),the USV determines whether the next step will fall into local optimization through the discriminationmechanism.The local potential field of the USV will dynamically adjust,and the reverse virtual gravitational potential field will be added to prevent it from falling into the local optimization and avoid collisions.The objective function and cost function are designed at the same time,so that the USV can smoothly switch between the global path and the local obstacle avoidance.The simulation results show that the improved APF algorithm proposed in this paper can successfully avoid various obstacles in the complex marine environment,and take navigation time and economic cost into account.
基金supported by the Aeronautical Science Foundation of China(20135584010)
文摘Focusing on obstacle avoidance in three-dimensional space for unmanned aerial vehicle(UAV), the direct obstacle avoidance method in dynamic space based on three-dimensional velocity obstacle spherical cap is proposed, which quantifies the influence of threatening obstacles through velocity obstacle spherical cap parameters. In addition, the obstacle avoidance schemes of any point on the critical curve during the multi-obstacles avoidance are given. Through prediction, the insertion point for the obstacle avoidance can be obtained and the flight path can be replanned. Taking the Pythagorean Hodograph(PH) curve trajectory re-planning as an example, the three-dimensional direct obstacle avoidance method in dynamic space is tested. Simulation results show that the proposed method can realize the online obstacle avoidance trajectory re-planning, which increases the flexibility of obstacle avoidance greatly.
基金TheNationalNaturalSienceFoundationofChina (No .6 2 385 2 )
文摘This paper presents a novel vision-based obstacle avoidance approach for the Autonomous Mobile Robot (AMR) with a Pan-Tilt-Zoom (PTZ) camera as its only sensing modality. The approach combines the morphological closing operation based on Sobel Edge Detection Operation and the (μ-kσ) thresholding technique to detect obstacles to soften the various lighting and ground floor effects. Both the morphology method and thresholding technique are computationally simple. The processing speed of the algorithm is fast enough to avoid some active obstacles. In addition, this approach takes into account the history obstacle effects on the current state. Fuzzy logic is used to control the behaviors of AMR as it navigates in the environment. All behaviors run concurrently and generate motor response solely based on vision perception. A priority based on subsumption coordinator selects the most appropriate response to direct the AMR away from obstacles. Validation of the proposed approach is done on a Pioneer 1 mobile robot.
基金Supported by Electronic Science Research Institute of China (No. BD02371)
文摘Rotorcraft in low-level flight is endangered by power lines or telephone wires. The development of automation tools that can detect obstacles in the flight path and warn the crew would significantly reduce pilot workload and increase safety. Therefore, a cable detection radar system is developed The real-time dynamic imaging synchronizing with radar space scanning has been implemented in developed ladar system. The requirements of the flight mission to prevent "wire strike" are analyzed and estimated, the advantages and disadvantages of the millimeter wave system with the laser system are weighted The result shows that Laser system is the best suited for helicopter avoidance obstacle. In addition, several design gist of detecting wire radar that was used in the developed ladar system is proposed and the developed zero backlash imaging technology and several advanced warning function are described. The detailed results of system ground tests and the performances description are presented The ground test of the developed ladar system has demonstrated that the developed imaging ladar system performance can achieve and satisfy the requirements of the mission to prevent "wire strike".
文摘由于果蔬采摘环境的不确定性和复杂性,机械臂在复杂环境中完成采摘,其路径规划需考虑实时避障。为实现采摘机械臂在不确定环境下安全采摘,提出一种改进RRT的动态避障算法,以提升机械臂在不确定采摘环境的适应性。针对基本快速扩展随机树算法(Rapidly-exploring Random Trees,RRT)在动态环境下迭代时间长、路径长、适应性差等问题,在RRT算法的基础上,引入目标导向策略,把终点以一定概率作为随机采样点的采样方向,提高算法的迭代效率;引入动态检测机制,对已完成规划的初始路径进行实时检测,使算法适应动态变化的环境。通过仿真分析改进RRT算法,结果表明:改进RRT算法的路径减少16%,迭代时间缩短86.5%;同时,动态检测机制使算法适应动态环境。
基金supported by the National Natural Science Foundation of China(No.61071016)
文摘For the issue of nuclear radiation detection,this paper designs a remote control nuclear radiation detector which can trace a pre-determined route,avoid obstacles effectively,and can be controlled remotely by users wirelessly or through voice command.It can effectively replace manual probing due to convenience,flexibility and safety.The system mainly consists of a nuclear detection module,a voice control module,a route tracing module,an obstacle avoidance module,a data transmission module,storage and a display module,and a D.C.machine.An MSP430 microcontroller is used as a control chip to control the motor and the system uses infrared technology and ultrasonic sensors to achieve intelligent tracing and obstacle avoidance.Moreover,it applies a voice module and data transmission module to remotely controlling the device.The radiation data is shown on an LCD screen.