Due to the unique steering mechanism and driving characteristics of the articulated vehicle,a hybrid path planning method based on the articulated vehicle model is proposed to meet the demand of obstacle avoidance and...Due to the unique steering mechanism and driving characteristics of the articulated vehicle,a hybrid path planning method based on the articulated vehicle model is proposed to meet the demand of obstacle avoidance and searching the path back and forth of the articulated vehicle.First,Support Vector Machine(SVM)theory is used to obtain the two-dimensional optimal zero potential curve and the maximum margin,and then,several key points are selected from the optimal zero potential curves by using Longest Accessible Path(LAP)method.Next,the Cubic Bezier(CB)curve is adopted to connect the curve that satisfies the curvature constraint of the articulated vehicle between every two key points.Finally,Back and Forth Rapidly-exploring Random Tree with Course Correction(BFRRT-CC)is designed to connect paths that do not meet articulated vehicle curvature requirements.Simulation results show that the proposed hybrid path planning method can search a feasible path with a 90-degree turn,which meets the demand for obstacle avoidance and articulated vehicle back-and-forth movement.展开更多
An articulated vehicle is simplified as a multibody system. tires are simplified asparagraphic linear springs with damping, and the differential equations of system motion aregiven. Taking the ZL10 loader as an exampl...An articulated vehicle is simplified as a multibody system. tires are simplified asparagraphic linear springs with damping, and the differential equations of system motion aregiven. Taking the ZL10 loader as an example, and measuring three-dimensional dynamicstiffness and damping of the tires, seven orders of natural frequencies and related natural modesare obtained by modal analysis, and shown on the computer with three-dimensional moving pic-tures. The following conclusions are obtained: the first order frequency relates to the horizontalstability, the second order frequency relates to the vertical stability, and each order of frequencyrelates to the comfortability. All results of this work can be applied .to monitor stability and eval-uate comfortability.展开更多
With the development and improvement of the hydraulic steering system,the articulated steering system became the research focus of numerous domestic and foreign scholars.The full hydraulic steering system with a compa...With the development and improvement of the hydraulic steering system,the articulated steering system became the research focus of numerous domestic and foreign scholars.The full hydraulic steering system with a compact structure and ease of operation,is widely used in articulated steering mode.Furthermore,its performance can directly impact the steering sensitivity and stability.This paper studies the working principle and actual structure of the priority valve and the steering control valve,which are very important.By setting up a mathematic model,the system’s load-sensing characteristics and the impact of steering control valve bypass throttle damping on steering stability can be analyzed.The Hydraulic Components Design(HCD)model was established for the hydraulic part of this system.It is proved that the model can reflect the system’s actual properties by comparing simulation and experimental results.The dynamic model is based on its actual prototype parameters by taking the tire and ground forces into account.The steering process’s dynamic characteristics are co-simulated in the 1D+3D system model by combining AMESim and Virtual.Lab Motion.The simulation results show that the system’s load-sensing characteristics ensure the sensitivity of the steering operation,and the bypass throttle damping has significantly improved the operation stability and lowered down the cylinder pressure fluctuations.This can improve the system performance by appropriate optimization.展开更多
针对铰接农用车在变附着系数路面条件下的路径跟踪精度难以保证的问题,提出了引入侧滑补偿的非线性模型预测控制(Nonlinear Model Predictive Control,NMPC)算法。首先,构建了考虑侧滑补偿的铰接农用车二自由度运动学模型,并基于该模型...针对铰接农用车在变附着系数路面条件下的路径跟踪精度难以保证的问题,提出了引入侧滑补偿的非线性模型预测控制(Nonlinear Model Predictive Control,NMPC)算法。首先,构建了考虑侧滑补偿的铰接农用车二自由度运动学模型,并基于该模型在Simulink中构建了NMPC控制器,最后以Adams环境中的虚拟铰接农用车为被控对象,以农业典型的地头转弯路径为参考路径,开展了变附着系数路面条件下的试验验证。结果表明,该算法的跟踪误差最大约为0.03 m,能够实现铰接农用车在变附着系数路面下的高精度路径跟踪。展开更多
To improve maneuverability and stability of articulated vehicles, we design an active steering controller, including tractor and trailer controllers, based on linear quadratic regulator(LQR) theory. First, a three-deg...To improve maneuverability and stability of articulated vehicles, we design an active steering controller, including tractor and trailer controllers, based on linear quadratic regulator(LQR) theory. First, a three-degree-of-freedom(3-DOF) model of the tractor-trailer with steered trailer axles is built. The simulated annealing particle swarm optimization(SAPSO) algorithm is applied to identify the key parameters of the model under specified vehicle speed and steering wheel angle. Thus, the key parameters of the simplified model can be obtained according to the vehicle conditions using an online look-up table and interpolation. Simulation results show that vehicle parameter outputs of the simplified model and Truck Sim agree well, thus providing the ideal reference yaw rate for the controller. Then the active steering controller of the tractor and trailer based on LQR is designed to follow the desired yaw rate and minimize their side-slip angle of the center of gravity(CG) at the same time. Finally, simulation tests at both low speed and high speed are conducted based on the Truck Sim-Simulink program. The results show significant effects on the active steering controller on improving maneuverability at low speed and lateral stability at high speed for the articulated vehicle. The control strategy is applicable for steering not only along gentle curves but also along sharp curves.展开更多
基金This work was supported by the Jiangsu Natural Science Foundation Project BK20170681National Natural Science Foundation of China 51675281.
文摘Due to the unique steering mechanism and driving characteristics of the articulated vehicle,a hybrid path planning method based on the articulated vehicle model is proposed to meet the demand of obstacle avoidance and searching the path back and forth of the articulated vehicle.First,Support Vector Machine(SVM)theory is used to obtain the two-dimensional optimal zero potential curve and the maximum margin,and then,several key points are selected from the optimal zero potential curves by using Longest Accessible Path(LAP)method.Next,the Cubic Bezier(CB)curve is adopted to connect the curve that satisfies the curvature constraint of the articulated vehicle between every two key points.Finally,Back and Forth Rapidly-exploring Random Tree with Course Correction(BFRRT-CC)is designed to connect paths that do not meet articulated vehicle curvature requirements.Simulation results show that the proposed hybrid path planning method can search a feasible path with a 90-degree turn,which meets the demand for obstacle avoidance and articulated vehicle back-and-forth movement.
文摘An articulated vehicle is simplified as a multibody system. tires are simplified asparagraphic linear springs with damping, and the differential equations of system motion aregiven. Taking the ZL10 loader as an example, and measuring three-dimensional dynamicstiffness and damping of the tires, seven orders of natural frequencies and related natural modesare obtained by modal analysis, and shown on the computer with three-dimensional moving pic-tures. The following conclusions are obtained: the first order frequency relates to the horizontalstability, the second order frequency relates to the vertical stability, and each order of frequencyrelates to the comfortability. All results of this work can be applied .to monitor stability and eval-uate comfortability.
基金This work was supported by the National Key Research and Development Program of China,No.2018YFB2000900。
文摘With the development and improvement of the hydraulic steering system,the articulated steering system became the research focus of numerous domestic and foreign scholars.The full hydraulic steering system with a compact structure and ease of operation,is widely used in articulated steering mode.Furthermore,its performance can directly impact the steering sensitivity and stability.This paper studies the working principle and actual structure of the priority valve and the steering control valve,which are very important.By setting up a mathematic model,the system’s load-sensing characteristics and the impact of steering control valve bypass throttle damping on steering stability can be analyzed.The Hydraulic Components Design(HCD)model was established for the hydraulic part of this system.It is proved that the model can reflect the system’s actual properties by comparing simulation and experimental results.The dynamic model is based on its actual prototype parameters by taking the tire and ground forces into account.The steering process’s dynamic characteristics are co-simulated in the 1D+3D system model by combining AMESim and Virtual.Lab Motion.The simulation results show that the system’s load-sensing characteristics ensure the sensitivity of the steering operation,and the bypass throttle damping has significantly improved the operation stability and lowered down the cylinder pressure fluctuations.This can improve the system performance by appropriate optimization.
文摘针对铰接农用车在变附着系数路面条件下的路径跟踪精度难以保证的问题,提出了引入侧滑补偿的非线性模型预测控制(Nonlinear Model Predictive Control,NMPC)算法。首先,构建了考虑侧滑补偿的铰接农用车二自由度运动学模型,并基于该模型在Simulink中构建了NMPC控制器,最后以Adams环境中的虚拟铰接农用车为被控对象,以农业典型的地头转弯路径为参考路径,开展了变附着系数路面条件下的试验验证。结果表明,该算法的跟踪误差最大约为0.03 m,能够实现铰接农用车在变附着系数路面下的高精度路径跟踪。
基金supported by the Program for Changjiang ScholarsInnovative Research Team in University,China(No.IRT0626)
文摘To improve maneuverability and stability of articulated vehicles, we design an active steering controller, including tractor and trailer controllers, based on linear quadratic regulator(LQR) theory. First, a three-degree-of-freedom(3-DOF) model of the tractor-trailer with steered trailer axles is built. The simulated annealing particle swarm optimization(SAPSO) algorithm is applied to identify the key parameters of the model under specified vehicle speed and steering wheel angle. Thus, the key parameters of the simplified model can be obtained according to the vehicle conditions using an online look-up table and interpolation. Simulation results show that vehicle parameter outputs of the simplified model and Truck Sim agree well, thus providing the ideal reference yaw rate for the controller. Then the active steering controller of the tractor and trailer based on LQR is designed to follow the desired yaw rate and minimize their side-slip angle of the center of gravity(CG) at the same time. Finally, simulation tests at both low speed and high speed are conducted based on the Truck Sim-Simulink program. The results show significant effects on the active steering controller on improving maneuverability at low speed and lateral stability at high speed for the articulated vehicle. The control strategy is applicable for steering not only along gentle curves but also along sharp curves.
