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Obstacle avoidance under relative localization uncertainty
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作者 Yang LYU Quan PAN +1 位作者 Jinwen HU Chunhui ZHAO 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第8期188-190,共3页
Dear editor, Collision avoidance is one of the classical to pics in robotics research. Collision avoidance control is guided by implementing typical collision avoidance methods, such as potential field [1], dynamic pr... Dear editor, Collision avoidance is one of the classical to pics in robotics research. Collision avoidance control is guided by implementing typical collision avoidance methods, such as potential field [1], dynamic programming [2], and geometrical calculation [3], to various platforms. Since these methods usually assume the perfect localization of an obstaele, they may not guarantee collision-free operations during the stochastic operation of robots wherein the obstacle is localized using noisy sensors. In particular, for micro aerial vehicles (MAVs), the potential obstaeles are detected using low-resolution sensors, such as cameras [4] and low-cost radars [5], leading to obstacle localization with high uncertainty. 展开更多
关键词 OBSTACLE AVOIDANCE COLLISION AVOIDANCE LOCALIZATION
Fuzzy Behavior-based Control of Three Wheeled Omnidirectional Mobile Robot
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作者 Nacer Hacene Boubekeur Mendil 《国际自动化与计算杂志:英文版》 EI CSCD 2019年第2期163-185,共23页
In this paper, a fuzzy behavior-based approach for a three wheeled omnidirectional mobile robot (TWOMR) navigation has been proposed. The robot has to track either static or dynamic target while avoiding either static... In this paper, a fuzzy behavior-based approach for a three wheeled omnidirectional mobile robot (TWOMR) navigation has been proposed. The robot has to track either static or dynamic target while avoiding either static or dynamic obstacles along its path. A simple controller design is adopted, and to do so, two fuzzy behaviors "Track the Target" and "Avoid Obstacles and Wall Following" are considered based on reduced rule bases (six and five rules respectively). This strategy employs a system of five ultrasonic sensors which provide the necessary information about obstacles in the environment. Simulation platform was designed to demonstrate the effectiveness of the proposed approach. 展开更多
关键词 THREE WHEELED OMNIDIRECTIONAL mobile robot (TWOMR) autonomous navigation obstacle AVOIDANCE FUZZY behaviorbased control DYNAMIC target DYNAMIC environment
基于STM32的四轴飞行器设计与实现 预览
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作者 刘宝媛 龚赛君 崔治 《电子测试》 2019年第19期22-23,37,共3页
本文设计了一种基于STM32F103RC单片机的四轴飞行器。该系统由核心控制模块、姿态传感器模块、超声波模块、摄像头模块等组成。姿态传感器模块、超声波模块和摄像头模块将检测到的姿态数据经过滤波和转化成四元数等操作后,通过串口传给... 本文设计了一种基于STM32F103RC单片机的四轴飞行器。该系统由核心控制模块、姿态传感器模块、超声波模块、摄像头模块等组成。姿态传感器模块、超声波模块和摄像头模块将检测到的姿态数据经过滤波和转化成四元数等操作后,通过串口传给核心控制模块里的PID控制器,最后输出PWM波给驱动模块。此外,采用超声波模块实现一键定高和避障,采用OpenMV摄像头模块用于循迹。测试结果表明,该系统实现了预期的设计功能。 展开更多
关键词 STM32 四轴飞行器 避障 循迹
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Formation control with obstacle avoidance of second-order multi-agent systems under directed communication topology
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作者 Guoxing WEN CLPhilip CHEN +2 位作者 Hui DOU Hongli YANG Chunfang LIU 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第9期144-157,共14页
This paper addresses the obstacle avoidance problem of formation control for the multi-agent systems modeled by double integrator dynamics under a directed interconnection topology. The control task is finished by a l... This paper addresses the obstacle avoidance problem of formation control for the multi-agent systems modeled by double integrator dynamics under a directed interconnection topology. The control task is finished by a leader-follower formation scheme combined with an artificial potential field(APF) method.The leader-follower scheme is carried out by taking the desired trajectory with the desired velocity as virtual leader, while the APF method is carried out by dealing with the obstacles as the high potential points. When the obstacle avoidance tasks are finished, the artificial potential forces degrade the formation performance, so their undesired effects are treated as disturbances, which is analyzed by the robust H∞performance. Based on Lyapunov stability theory, it is proved that the proposed formation approach can realize the control objective. The result is also extended to the switching multi-agent formation. The effectiveness of the proposed formation scheme is further confirmed by simulation studies. 展开更多
关键词 formation control OBSTACLE AVOIDANCE artificial potential field method H_∞ performance SECOND-ORDER multi-agent system directed TOPOLOGY
论意定代理授权行为的取消——兼释《民法总则》第173条第2项前半句
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作者 崔拴林 《法学家》 CSSCI 北大核心 2019年第2期72-83,193共13页
《民法总则》第173条第2项前半句规定的'取消委托'不应解释为意定代理内部基础关系的无效或失效,而应解释为授权行为生效后非由于意思瑕疵被收回。授权行为生效后非由于意思瑕疵被收回也不应被界定为'撤回'或'撤销&... 《民法总则》第173条第2项前半句规定的'取消委托'不应解释为意定代理内部基础关系的无效或失效,而应解释为授权行为生效后非由于意思瑕疵被收回。授权行为生效后非由于意思瑕疵被收回也不应被界定为'撤回'或'撤销',而应界定为'取消'。这样才能使《民法总则》第173条第2项前半句规定的'取消'实至名归,才能确保意定代理制度中导致授权行为不生效或者丧失效力的三种意定事由在概念和逻辑上的清晰与和谐,也才能使民法典意定代理法的相关概念和规则与欧美代理法中的通行做法接轨。 展开更多
关键词 意定代理 授权行为 取消 撤回 撤销
地月L2点中继星长阴影影响研究 预览
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作者 梁伟光 刘磊 +1 位作者 刘勇 马传令 《深空探测学报》 2019年第1期52-56,共5页
地月L2点中继星环绕地月L2点飞行时,会经历由地球或月球遮挡太阳而产生的阴影,部分阴影时长较长,中继星进入长阴影,严重时会威胁卫星平台安全。基于月球背面软着陆探测工程目标和中继星绕飞地月L2点halo轨道特性,分析长阴影的分布特征,... 地月L2点中继星环绕地月L2点飞行时,会经历由地球或月球遮挡太阳而产生的阴影,部分阴影时长较长,中继星进入长阴影,严重时会威胁卫星平台安全。基于月球背面软着陆探测工程目标和中继星绕飞地月L2点halo轨道特性,分析长阴影的分布特征,以及阴影时长与轨道相位、振幅、构型等因素的关系,进而对长阴影的规避方法和适用范围进行探讨。研究结果为地月L2点中继星长阴影问题提供了分析方法和应对方案。 展开更多
关键词 长阴影 中继星 地月L2点 规避 调相
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基于强化学习的自主式水下潜器障碍规避技术 预览
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作者 Prashant Bhopale Faruk Kazi Navdeep Singh 《船舶与海洋工程学报:英文版》 CSCD 2019年第2期228-238,共11页
Obstacle avoidance becomes a very challenging task for an autonomous underwater vehicle(AUV)in an unknown underwater environment during exploration process.Successful control in such case may be achieved using the mod... Obstacle avoidance becomes a very challenging task for an autonomous underwater vehicle(AUV)in an unknown underwater environment during exploration process.Successful control in such case may be achieved using the model-based classical control techniques like PID and MPC but it required an accurate mathematical model of AUV and may fail due to parametric uncertainties,disturbance,or plant model mismatch.On the other hand,model-free reinforcement learning(RL)algorithm can be designed using actual behavior of AUV plant in an unknown environment and the learned control may not get affected by model uncertainties like a classical control approach.Unlike model-based control model-free RL based controller does not require to manually tune controller with the changing environment.A standard RL based one-step Q-learning based control can be utilized for obstacle avoidance but it has tendency to explore all possible actions at given state which may increase number of collision.Hence a modified Q-learning based control approach is proposed to deal with these problems in unknown environment.Furthermore,function approximation is utilized using neural network(NN)to overcome the continuous states and large statespace problems which arise in RL-based controller design.The proposed modified Q-learning algorithm is validated using MATLAB simulations by comparing it with standard Q-learning algorithm for single obstacle avoidance.Also,the same algorithm is utilized to deal with multiple obstacle avoidance problems. 展开更多
关键词 OBSTACLE AVOIDANCE AUTONOMOUS UNDERWATER vehicle Reinforcement learning Q-LEARNING Function APPROXIMATION
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A Fundamental Study on Multi-agent Pedestrian Model Based on Risk Avoidance Behavior during Road Blockage and Evacuation Simulation of Regional Urban Disaster 预览
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作者 Hideaki Takayanagi Tatsuto Kihara +5 位作者 Yosuke Kurita Kazuhide Kawaguchi Hidetoshi Kawaguchi Takaaki Furukawa Takuhi Ono Shogo Yamada 《土木工程与建筑:英文版》 2019年第4期219-237,共19页
Regional cities in Japan are at the risk of experiencing big fire accidents or earthquakes every day.However,neither the number nor the capacity of shelters has increased because local governments might not consider t... Regional cities in Japan are at the risk of experiencing big fire accidents or earthquakes every day.However,neither the number nor the capacity of shelters has increased because local governments might not consider them owing to budget shortfall.By contrast,wide-area evacuation simulations can easily provide an antagonizing image of regional urban disasters.After a disaster,the city collapses and the evacuation routes are closed;consequently,evacuees feel anxious and they cannot move as usual.This anxiety behavior has not been considered in previous related studies and simulations.In this study,a wide-area evacuation simulation is developed;this model can not only calculate the possibility of blocking escape routes when the city is broken but also provide safe and more realistic evacuation plans before a disaster occurs by incorporating into the simulation the risk avoidance behaviors of evacuees from road blockage,such as“the route re-seeking behavior”and“the shelter re-selecting behavior”. 展开更多
关键词 Wide-area EVACUATION simulation MULTI-AGENT model risk AVOIDANCE BEHAVIOR regional DISASTER prevention plan
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水锤的产生及有效规避 预览
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作者 李永红 段世良 郭孟彩 《河南科技》 2019年第4期45-46,共2页
工厂生产过程中供水系统的安全是保证工厂连续高效生产的重要环节。水锤问题是工厂供水系统中经常遇到的问题,诱发原因可能存在于设计、安装、使用的各个过程。寻求水锤问题的有效规避办法,从理论和实际应用中整理出一套完整解决方法,... 工厂生产过程中供水系统的安全是保证工厂连续高效生产的重要环节。水锤问题是工厂供水系统中经常遇到的问题,诱发原因可能存在于设计、安装、使用的各个过程。寻求水锤问题的有效规避办法,从理论和实际应用中整理出一套完整解决方法,保证供水系统的安全高效,显得很有必要。本文将结合一个具体工程论述相关问题。 展开更多
关键词 水锤 连续高效 安全 规避
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Collision free 4D path planning for multiple UAVs based on spatial refined voting mechanism and PSO approach
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作者 Yang LIU Xuejun ZHANG +1 位作者 Yu ZHANG Xiangmin GUAN 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第6期1504-1519,共16页
In this paper, a four-dimensional coordinated path planning algorithm for multiple UAVs is proposed, in which time variable is taken into account for each UAV as well as collision free and obstacle avoidance. A Spatia... In this paper, a four-dimensional coordinated path planning algorithm for multiple UAVs is proposed, in which time variable is taken into account for each UAV as well as collision free and obstacle avoidance. A Spatial Refined Voting Mechanism(SRVM) is designed for standard Particle Swarm Optimization(PSO) to overcome the defects of local optimal and slow convergence.For each generation candidate particle positions are recorded and an adaptive cube is formed with own adaptive side length to indicate occupied regions. Then space voting begins and is sorted based on voting results, whose centers with bigger voting counts are seen as sub-optimal positions. The average of all particles of corresponding dimensions are calculated as the refined solutions. A time coordination method is developed by generating specified candidate paths for every UAV, making them arrive the same destination with the same time consumption. A spatial-temporal collision avoidance technique is introduced to make collision free. Distance to destination is constructed to improve the searching accuracy and velocity of particles. In addition, the objective function is redesigned by considering the obstacle and threat avoidance, Estimated Time of Arrival(ETA), separation maintenance and UAV self-constraints. Experimental results prove the effectiveness and efficiency of the algorithm. 展开更多
关键词 4D path planning Collision free Multiple UAVS OBSTACLE AVOIDANCE Particle SWARM optimization SPATIAL refined VOTING mechanism
Use of the average age ratio method in analyzing age heaping in censuses:The case of China 预览
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作者 Danan Gu Qiushi Feng 《国际人口学期刊》 2019年第1期13-26,共14页
Based on the methods of the average period age ratio and the average cohort age ratio,this study systematically assesses age heaping or digit preference in all population censuses of China.Our study finds that the ove... Based on the methods of the average period age ratio and the average cohort age ratio,this study systematically assesses age heaping or digit preference in all population censuses of China.Our study finds that the overall age heaping was relatively low in the Chinese censuses;however,there was a notable preference for ages ending with zero after age 50 in the first two censuses,despite a weakening trend over time.Our study further shows that age heaping in China’s censuses is likely associated with age-related policies such as those on late marriage and retirement.As shown in the study,the average age ratio method can be an alternative of the Whipple’s Index and be improved if the size of birth cohort was taken into account when the number of births is generally reliable. 展开更多
关键词 Age concentration INDEX Age heaping age RATIO Age reporting AVERAGE age RATIO AVERAGE period age RATIO AVERAGE cohort age RATIO China CENSUS DIGIT preference DIGIT AVOIDANCE Whipple’s INDEX Myer’s blended INDEX
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解耦控制仿真实验设计与解算错误规避 预览
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作者 侯明 付兴建 +2 位作者 关静丽 陈雯柏 柏森 《实验室研究与探索》 CAS 北大核心 2019年第3期101-105,共5页
为促进学生对解耦控制的深入理解,设计了基于Simulink的仿真实验,在设计方案无误的情况下,发现仿真结果与理论分析差异较大,这将可能误导学生对知识的理解。通过研究仿真架构在不同仿真条件下的响应结果的差异,发现Simulink在处理冲激... 为促进学生对解耦控制的深入理解,设计了基于Simulink的仿真实验,在设计方案无误的情况下,发现仿真结果与理论分析差异较大,这将可能误导学生对知识的理解。通过研究仿真架构在不同仿真条件下的响应结果的差异,发现Simulink在处理冲激响应时,不同的解算方法结果差异很大,进一步分析产生差异的原因。综合一些实际因素,提出改善的方法,即能保证解耦控制结果基本正确反映理论,也能对残留的误差找到符合逻辑的解释,使得理论内容与仿真结果达到统一。 展开更多
关键词 解耦控制 实验设计 解算 冲激响应 规避
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基于STM32的智能物流机器人控制设计 预览
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作者 张帅 洪文辉 +2 位作者 朱镇坤 邢健豪 谭洪 《信息技术与信息化》 2019年第7期98-100,共3页
物流产业的迅速发展使得智能物流技术有着广阔的应用前景,选用STM32F013ZET6为主控芯片,设计制作了智能物流搬运小车。具有在特定场地自主循迹,场内定位,自主读取二维码,识别颜色,物流搬运等功能。小车四周装有超声波传感器可实现一定... 物流产业的迅速发展使得智能物流技术有着广阔的应用前景,选用STM32F013ZET6为主控芯片,设计制作了智能物流搬运小车。具有在特定场地自主循迹,场内定位,自主读取二维码,识别颜色,物流搬运等功能。小车四周装有超声波传感器可实现一定范围的自主避障功能,同时装有ESP8266传感器可实现与PC通信,远程接收任务指令,实现对物流的运输存放。 展开更多
关键词 STM32 定位 避障 PID算法 摄像头识别
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Association of Varroa destructor females in multiply infested cells of the honeybee Apis mellifera
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作者 Alexis L.Beaurepaire James D.Ellis +1 位作者 Klemens J.Krieger Robin F.A.Moritz 《昆虫科学:英文版》 SCIE CAS CSCD 2019年第1期128-134,共7页
The genetic diversity of Varroa destructor (Anderson &Trueman)is limited outside its natural range due to population bottlenecks and its propensity to inbreed.In light of the arms race between V.destructor and its... The genetic diversity of Varroa destructor (Anderson &Trueman)is limited outside its natural range due to population bottlenecks and its propensity to inbreed.In light of the arms race between V.destructor and its honeybee (Apis mellifera L.)host, any mechanism enhancing population admixture of the mite may be favored.One way that admixture can occur is when two genetically dissimilar mites coinvade a brood cell, with the progeny of the foundresses admixing.We determined the relatedness of 393 pairs of V.destructor foundresses,each pair collected from a single bee brood cell (n =five colonies).We used six microsatellites to identify the genotypes of mites coinvading a cell and calculated the frequency of pairs with different or the same genotypes.We found no deviation from random coinvasion,but the frequency of cells infested by mites with different genotypes was high.This rate of recombination,coupled with a high transmission rate of mites,homogenized the allelic pool of mites within the apiary. 展开更多
关键词 APIS MELLIFERA HOST-PARASITE coevolution INBREEDING avoidance mating behavior population genetics VARROA destructor
A Study on Development of a Hybrid Aerial/Terrestrial Robot System for Avoiding Ground Obstacles by Flight 预览
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作者 Chinthaka Premachandra Masahiro Otsuka +2 位作者 Ryo Gohara Takao Ninomiya Kiyotaka Kato 《自动化学报:英文版》 CSCD 2019年第1期327-336,共10页
To date, many studies related to robots have been performed around the world. Many of these studies have assumed operation at locations where entry is difficult, such as disaster sites, and have focused on various ter... To date, many studies related to robots have been performed around the world. Many of these studies have assumed operation at locations where entry is difficult, such as disaster sites, and have focused on various terrestrial robots, such as snake-like, humanoid, spider-type, and wheeled units. Another area of active research in recent years has been aerial robots with small helicopters for operation indoors and outdoors. However,less research has been performed on robots that operate both on the ground and in the air. Accordingly, in this paper, we propose a hybrid aerial/terrestrial robot system. The proposed robot system was developed by equipping a quadcopter with a mechanism for ground movement. It does not use power dedicated to ground movement, and instead uses the flight mechanism of the quadcopter to achieve ground movement as well. Furthermore, we addressed the issue of obstacle avoidance as part of studies on autonomous control. Thus, we found that autonomous control of ground movement and flight was possible for the hybrid aerial/terrestrial robot system, as was autonomous obstacle avoidance by flight when an obstacle appeared during ground movement. 展开更多
关键词 GROUND movement/flight control HYBRID aerial/terrestrial robot OBSTACLE avoidance by FLIGHT OBSTACLE recognition
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UGNX数控车编程优化设置的研究 预览
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作者 郭世帅 《内燃机与配件》 2018年第5期55-57,共3页
通过编程实例,探讨在UGNX数控车编程中利用添加事件处理、设置避让点和优化切削参数等方法与技巧,达到优化程序,提高程序的安全性、加工精度加工效率的目的。
关键词 UGNX 事件 避让点(AVOIDANCE)
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Conditioned taste aversions
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作者 Kathleen C. Chambers 《世界耳鼻咽喉头颈外科杂志(英文)》 2018年第1期92-100,共9页
When one becomes ill after consuming a meal, there is a propensity to target a particular taste as the cause of the illness. The qualities of the taste most likely targeted include more novel, less preferred, and high... When one becomes ill after consuming a meal, there is a propensity to target a particular taste as the cause of the illness. The qualities of the taste most likely targeted include more novel, less preferred, and higher protein content. This association between a particular taste and illness is a form of learning that is termed conditioned taste aversion (CTA). A consequence of the learned association is that the taste will become aversive. When experiencing the taste again, individuals will show aversive reactions such as expressions of loathing, will experience mimicked illness sensations such as nausea, and subsequently, will avoid further exposure to the taste. The ability to acquire CTA occurs across species and across ages within a species. In the rat animal model, however, age differences exist in the capability of acquiring CTAs when increasingly longer intervals are imposed between consumption of a novel sweet solution and onset of illness. Pups have a decreased ability compared to young adults while aged rats have an increased ability. Evidence suggests that the failure of pups to acquire CTA at longer intervals is due to an immature retrieval mechanism and the facili-tated ability of aged rats is due to a compromised clock mechanism that tracks the passage of time. Learned taste-illness association serves the critical function of informing individuals of the toxic nature of certain foods, thus preventing further illness and potentially death. Additionally, it contributes to the hypophagia observed during cancer chemotherapy and may contribute to the hypophagia found while suffering from bacterial infection, chronic med-ical conditions such as cancer, and restrictive food intake disorders such as anorexia nervosa. 展开更多
关键词 Age DIFFERENCES AVERSION REACTIONS AVOIDANCE HYPOPHAGIA Illness SENSATIONS
Research on Avoidance Behavior in the English Writing of English Majors 预览
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作者 崔金枝 《海外英语》 2018年第21期242-244,共3页
关键词 AVOIDANCE ENGLISH WRITING ENGLISH majors
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基于“τ-τ”的无人机规避告警准则分析
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作者 张志伟 陶建武 邵校 《系统仿真学报》 CSCD 北大核心 2018年第5期1877-1884,1892共9页
在无人机规避障碍的过程中,引入了基于时间τ告警逻辑,并在此基础上提出了基于时间τ-τ告警逻辑,构建了等τ-τ告警曲线。 根据自身无人机所进行机动动作的幅度,定义了三种告警区域,即高风险区、低风险区以及无风险区。该方法分... 在无人机规避障碍的过程中,引入了基于时间τ告警逻辑,并在此基础上提出了基于时间τ-τ告警逻辑,构建了等τ-τ告警曲线。 根据自身无人机所进行机动动作的幅度,定义了三种告警区域,即高风险区、低风险区以及无风险区。该方法分别针对两架飞机在平行相遇情形和垂直交叉相遇情形下,按照自身无人机速度大于、等于和小于入侵无人机速度三种不同情况,利用MATLAB软件仿真出两架飞机不同相对速度下的告警曲线,提出了告警区域的划分方法,重点分析了不同相遇情形中告警区的区别。所得实验结果为无人机规避策略的制定提供了数据支撑。 展开更多
关键词 无人机 规避 等τ-τ线 告警区域
母语为俄语的学习者对汉语话语标记习得的文化迁移模式 被引量:1
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作者 黄彩玉 谢红宇 《外语学刊》 CSSCI 北大核心 2018年第4期65-69,共5页
本文以俄罗斯学生汉语话语标记习得和使用情况为基础,从社会距离和心理距离两个角度探讨话语标记习得的文化迁移模式。努力营造和利用目的语环境,给予学生足量可理解的输入,才能在话语标记学习过程中缩小学习者与目的语群体的社会距... 本文以俄罗斯学生汉语话语标记习得和使用情况为基础,从社会距离和心理距离两个角度探讨话语标记习得的文化迁移模式。努力营造和利用目的语环境,给予学生足量可理解的输入,才能在话语标记学习过程中缩小学习者与目的语群体的社会距离。留学生对于话语标记的使用多采取消极规避的交际策略,主要原因是汉文化语境衍生出多元语用功能和文化内涵,留学生难以克服母语思维习惯和表达方式。 展开更多
关键词 话语标记习得 文化迁移模式 社会距离 心理距离 消极规避
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