E-WID(Euler-number-based whole-object intersection and difference)三维拓扑关系模型能够表达三维空间简单、复杂目标间的拓扑关系,具有区分能力强、无理论缺陷等优势,但目前尚缺乏E-WID三维模型自动计算的相关研究。因此,利用Nef...E-WID(Euler-number-based whole-object intersection and difference)三维拓扑关系模型能够表达三维空间简单、复杂目标间的拓扑关系,具有区分能力强、无理论缺陷等优势,但目前尚缺乏E-WID三维模型自动计算的相关研究。因此,利用Nef多面体三维数据模型能够表达带通道或空穴等复杂目标的特点,本文研究了一种基于Nef多面体的E-WID三维基本拓扑关系计算方法,其中包括三维基本空间数据间布尔运算结果的组件构建和欧拉数计算方法;并与已有方法进行对比。结果表明,本文方法实现了三维空间数据间的E-WID三维基本拓扑关系自动计算,并能够准确区分。展开更多
A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The...A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The front axle and rear axle of the vehicle chassis could rotate simultaneously around their respective center points and cut the turning radius in half at most through specific mechanical chassis structure design and four-wheel electrical drive.It had great potential to reduce wheel traffic damage to field crops if two rear electrical drive wheels can be controlled to follow wheel tracks of two front wheels during self-steering operation.Therefore,firstly,a two-degree-freedom dynamics model presenting this agricultural electric vehicle was constructed.Then,an MPC controller combined with DYC was applied to arrange torques from four wheels to match desired turning angles,direct yaw moments and travel speeds.The simulation results existed small steady error of steering angles below 0.22%as they were set at 5°,followed with yaw moment under 0.17%and velocity less than 1%.Finally,according to experiment results,the vehicle successfully made a working turning radius of 9.1 m with maximum error of 0.55%when desired steering angles were 5°at the speed of 1 m/s and a minimum turning radius of 1.51 m with maximum error of 6.6%when steering angles were 30°at the speed of 0.5 m/s.It verified that the 4WID agricultural electric vehicle could drive autonomously and steady with small self-steering angle error under the proposed control system and has a feasibility to reduce wheel traffic damage during driving and operation.展开更多
文摘E-WID(Euler-number-based whole-object intersection and difference)三维拓扑关系模型能够表达三维空间简单、复杂目标间的拓扑关系,具有区分能力强、无理论缺陷等优势,但目前尚缺乏E-WID三维模型自动计算的相关研究。因此,利用Nef多面体三维数据模型能够表达带通道或空穴等复杂目标的特点,本文研究了一种基于Nef多面体的E-WID三维基本拓扑关系计算方法,其中包括三维基本空间数据间布尔运算结果的组件构建和欧拉数计算方法;并与已有方法进行对比。结果表明,本文方法实现了三维空间数据间的E-WID三维基本拓扑关系自动计算,并能够准确区分。
基金This research work was funded by the National Natural Science Foundation of China(Grant No.51975260)Jiangsu Provincial Key Research and Development Program(Grant No.BE2018372),Jiangsu Natural Science Foundation(Grant No.BK20181443)+1 种基金Zhenjiang City Key Research and Development Program(Grant No.NY2018001)Qing Lan Project of Jiangsu Province,the Priority Academic Program Development(PAPD)of the Jiangsu Higher Education Institutions,China.The authors would like to acknowledge the other colleagues of the team for providing assistance in the experiment.
文摘A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The front axle and rear axle of the vehicle chassis could rotate simultaneously around their respective center points and cut the turning radius in half at most through specific mechanical chassis structure design and four-wheel electrical drive.It had great potential to reduce wheel traffic damage to field crops if two rear electrical drive wheels can be controlled to follow wheel tracks of two front wheels during self-steering operation.Therefore,firstly,a two-degree-freedom dynamics model presenting this agricultural electric vehicle was constructed.Then,an MPC controller combined with DYC was applied to arrange torques from four wheels to match desired turning angles,direct yaw moments and travel speeds.The simulation results existed small steady error of steering angles below 0.22%as they were set at 5°,followed with yaw moment under 0.17%and velocity less than 1%.Finally,according to experiment results,the vehicle successfully made a working turning radius of 9.1 m with maximum error of 0.55%when desired steering angles were 5°at the speed of 1 m/s and a minimum turning radius of 1.51 m with maximum error of 6.6%when steering angles were 30°at the speed of 0.5 m/s.It verified that the 4WID agricultural electric vehicle could drive autonomously and steady with small self-steering angle error under the proposed control system and has a feasibility to reduce wheel traffic damage during driving and operation.
