Autonomous-rail rapid transit(ART)is a new medium-capacity rapid transportation system with punctuality,comfort and convenience,but low-cost construction.Combined velocity planning is a critical approach to meet the r...Autonomous-rail rapid transit(ART)is a new medium-capacity rapid transportation system with punctuality,comfort and convenience,but low-cost construction.Combined velocity planning is a critical approach to meet the requirements of energy-saving and punctuality.An ART velocity pre-planning and re-planning strategy based on the combination of punctuality dynamic programming(PDP)and pseudospectral(PS)method is proposed in this paper.Firstly,the longitudinal dynamics model of ART is established by a multi-particle model.Secondly,the PDP algorithm with global optimal characteristics is adopted as the pre-planning strategy.A model for determining the number of collocation points of the real-time PS method is proposed to improve the energy-saving effect while ensuring computation efficiency.Then the enhanced PS method is utilized to design the velocity re-planning strategy.Finally,simulations are conducted in the typical scenario with sloping roads,traffic lights,and intrusion of the pedestrian.The simulation results indicate that the ART with the proposed velocity trajectory optimization strategy can meet the punctuality requirement,and obtain better economy efficiency compared with the punctuality green light optimal speed advisory(PGLOSA).展开更多
This study proposes a new nonlinear tracking control method with safe angular velocity constraints for a cushion robot. A fuzzy path planning algorithm is investigated and a realtime desired motion path of obstacle av...This study proposes a new nonlinear tracking control method with safe angular velocity constraints for a cushion robot. A fuzzy path planning algorithm is investigated and a realtime desired motion path of obstacle avoidance is obtained. The angular velocity is constrained by the controller, so the planned path guarantees the safety of users. According to Lyapunov theory, the controller is designed to maintain stability in terms of solutions of linear matrix inequalities and the controller's performance with safe angular velocity constraints is derived.The simulation and experiment results confirm the effectiveness of the proposed method and verify that the angular velocity of the cushion robot provided safe motion with obstacle avoidance.展开更多
High-speed parallel robots have been extensively utilized in the light industry.However,the influence of the nonlinear dynamic characteristics of high-speed parallel robots on system’s dynamic response and stable ope...High-speed parallel robots have been extensively utilized in the light industry.However,the influence of the nonlinear dynamic characteristics of high-speed parallel robots on system’s dynamic response and stable operation cannot be ignored during the high-speed reciprocating motion.Thus,trajectory planning is essential for efficiency and stability from pick-and-place(PAP)actions.This paper presents a method for planning the equal-height pick-and-place trajectory considering velocity constraints to improve the PAP efficiency and stability of high-speed parallel robots.The velocity constraints in the start-and-end points can reduce vibration from picking and placing,making the trajectory more suitable to complex beltline situations.Based on velocity constraints,trajectory optimization includes trajectory smoothness and joint torque to optimize cycle time is carried out.This paper proposes an online trajectory optimization solution.By using back propagation(BP)neural networks,the solution is simplified and can be solved in real-time.Simulation and experiments were carried out on the SR4 parallel robot.The results show that the proposed method improves the efficiency,smoothness,and stability of the robot.This paper proposes an online trajectory planning method which is velocity constraints based and can improve the efficiency and stability of high-speed parallel robots.The work of this research is conducive to finely applying high-speed parallel robots.展开更多
For permanent magnet linear synchronous motor(PMLSM) working at trapezoidal speed for long time, high thrust brings high temperature rise, while low thrust limits dynamic performance. Thus, it is crucial to find a bal...For permanent magnet linear synchronous motor(PMLSM) working at trapezoidal speed for long time, high thrust brings high temperature rise, while low thrust limits dynamic performance. Thus, it is crucial to find a balance between temperature rise and dynamic performance. In this paper, a velocity planning model of the PMLSM at trapezoidal speed based on electromagnetic-fluid-thermal(EFT) field is proposed to obtain the optimal dynamic performance under temperature limitation. In this model, the winding loss is calculated considering the acceleration and deceleration time. The loss model is indirectly verified by the temperature rise experiment of an annular winding sample. The actual working conditions of the PMLSM are simulated by dynamic grid technology to research the influence of acceleration and deceleration on fluid flow in the air gap, and the variation rule of the thermal boundary condition is analyzed. Combined with the above conditions, the temperature rise of a coreless PMLSM(CPMLSM) under the rated working condition is calculated and analyzed in detail. Through this method and several iterations, the optimal dynamic performance under the temperature limitation is achieved. The result is verified by a comparison between simulation and prototype tests, which can help improve the dynamic performance.展开更多
Most researches focus on the regenerative braking system design in vehicle components control and braking torque distribution,few combine the connected vehicle technologies into braking velocity planning.If the brakin...Most researches focus on the regenerative braking system design in vehicle components control and braking torque distribution,few combine the connected vehicle technologies into braking velocity planning.If the braking intention is accessed by the vehicle-to-everything communication,the electric vehicles(EVs)could plan the braking velocity for recovering more vehicle kinetic energy.Therefore,this paper presents an energy-optimal braking strategy(EOBS)to improve the energy efficiency of EVs with the consideration of shared braking intention.First,a double-layer control scheme is formulated.In the upper-layer,an energy-optimal braking problem with accessed braking intention is formulated and solved by the distance-based dynamic programming algorithm,which could derive the energy-optimal braking trajectory.In the lower-layer,the nonlinear time-varying vehicle longitudinal dynamics is transformed to the linear time-varying system,then an efficient model predictive controller is designed and solved by quadratic programming algorithm to track the original energy-optimal braking trajectory while ensuring braking comfort and safety.Several simulations are conducted by jointing MATLAB and CarSim,the results demonstrated the proposed EOBS achieves prominent regeneration energy improvement than the regular constant deceleration braking strategy.Finally,the energy-optimal braking mechanism of EVs is investigated based on the analysis of braking deceleration,battery charging power,and motor efficiency,which could be a guide to real-time control.展开更多
Sharp corners usually are used on glass contours to meet the highly increasing demand for personalized products,but they result in a broken wheel center toolpath in edge grinding.To ensure that the whole wheel center ...Sharp corners usually are used on glass contours to meet the highly increasing demand for personalized products,but they result in a broken wheel center toolpath in edge grinding.To ensure that the whole wheel center toolpath is of G1 continuity and that the grinding depth is controllable at the corners,a transition toolpath generation method based on a velocity-blending algorithm is proposed.Taking the grinding depth into consideration,the sharp-corner grinding process is planned,and a velocity-blending algorithm is introduced.With the constraints,such as traverse displacement and grinding depth,the sharp-corner transition toolpath is generated with a three-phase motion arrangement and with confirmations of the acceleration/deceleration positions.A piece of glass with three sharp corners is ground on a three-axis numerical-control glass grinding equipment.The experimental results demonstrate that the proposed algorithm can protect the sharp corners from breakage efficiently and achieve satisfactory shape accuracy.This research proposed a toolpath generation method based on a velocity-blending algorithm for the manufacturing of personalized glass products,which generates the transition toolpath as needed around a sharp corner in real time.展开更多
In order to satisfy the high efficiency and high precision of collaborative robots,this work presents a novel trajectory planning method.First,in Cartesian space,a novel velocity look-ahead control algorithm and a cub...In order to satisfy the high efficiency and high precision of collaborative robots,this work presents a novel trajectory planning method.First,in Cartesian space,a novel velocity look-ahead control algorithm and a cubic polynomial are combined to construct the end-effector trajectory of robots.Then,the joint trajectories can be obtained through the inverse kinematics.In order to improve the smoothness and stability in joint space,the joint trajectories are further adjusted based on the velocity look-ahead control algorithm and quintic B-spline.Finally,the proposed trajectory planning method is tested on a 4-DOF serial collaborative robot.The experimental results indicate that the collaborative robot achieves the high efficiency and high precision,which validates the effectiveness of the proposed method.展开更多
Path planning for space vehicles is still a challenging problem although considerable progress has been made over the past decades.The major difficulties are that most of existing methods only adapt to static environm...Path planning for space vehicles is still a challenging problem although considerable progress has been made over the past decades.The major difficulties are that most of existing methods only adapt to static environment instead of dynamic one,and also can not solve the inherent constraints arising from the robot body and the exterior environment.To address these difficulties,this research aims to provide a feasible trajectory based on quadratic programming(QP) for path planning in three-dimensional space where an autonomous vehicle is requested to pursue a target while avoiding static or dynamic obstacles.First,the objective function is derived from the pursuit task which is defined in terms of the relative distance to the target,as well as the angle between the velocity and the position in the relative velocity coordinates(RVCs).The optimization is in quadratic polynomial form according to QP formulation.Then,the avoidance task is modeled with linear constraints in RVCs.Some other constraints,such as kinematics,dynamics,and sensor range,are included.Last,simulations with typical multiple obstacles are carried out,including in static and dynamic environments and one of human-in-the-loop.The results indicate that the optimal trajectories of the autonomous robot in three-dimensional space satisfy the required performances.Therefore,the QP model proposed in this paper not only adapts to dynamic environment with uncertainty,but also can satisfy all kinds of constraints,and it provides an efficient approach to solve the problems of path planning in three-dimensional space.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.52072073 and 52025121)National Key R&D Program of China(Grant No.2018YFB1201602).
文摘Autonomous-rail rapid transit(ART)is a new medium-capacity rapid transportation system with punctuality,comfort and convenience,but low-cost construction.Combined velocity planning is a critical approach to meet the requirements of energy-saving and punctuality.An ART velocity pre-planning and re-planning strategy based on the combination of punctuality dynamic programming(PDP)and pseudospectral(PS)method is proposed in this paper.Firstly,the longitudinal dynamics model of ART is established by a multi-particle model.Secondly,the PDP algorithm with global optimal characteristics is adopted as the pre-planning strategy.A model for determining the number of collocation points of the real-time PS method is proposed to improve the energy-saving effect while ensuring computation efficiency.Then the enhanced PS method is utilized to design the velocity re-planning strategy.Finally,simulations are conducted in the typical scenario with sloping roads,traffic lights,and intrusion of the pedestrian.The simulation results indicate that the ART with the proposed velocity trajectory optimization strategy can meet the punctuality requirement,and obtain better economy efficiency compared with the punctuality green light optimal speed advisory(PGLOSA).
基金supported by the Program for Liaoning Excellent Talents in University of China(LJQ2014013)the Liaoning Natural Science Foundation of China(2015020066)
文摘This study proposes a new nonlinear tracking control method with safe angular velocity constraints for a cushion robot. A fuzzy path planning algorithm is investigated and a realtime desired motion path of obstacle avoidance is obtained. The angular velocity is constrained by the controller, so the planned path guarantees the safety of users. According to Lyapunov theory, the controller is designed to maintain stability in terms of solutions of linear matrix inequalities and the controller's performance with safe angular velocity constraints is derived.The simulation and experiment results confirm the effectiveness of the proposed method and verify that the angular velocity of the cushion robot provided safe motion with obstacle avoidance.
基金National Natural Science Foundation of China(Grant Nos.51922057,91948301).
文摘High-speed parallel robots have been extensively utilized in the light industry.However,the influence of the nonlinear dynamic characteristics of high-speed parallel robots on system’s dynamic response and stable operation cannot be ignored during the high-speed reciprocating motion.Thus,trajectory planning is essential for efficiency and stability from pick-and-place(PAP)actions.This paper presents a method for planning the equal-height pick-and-place trajectory considering velocity constraints to improve the PAP efficiency and stability of high-speed parallel robots.The velocity constraints in the start-and-end points can reduce vibration from picking and placing,making the trajectory more suitable to complex beltline situations.Based on velocity constraints,trajectory optimization includes trajectory smoothness and joint torque to optimize cycle time is carried out.This paper proposes an online trajectory optimization solution.By using back propagation(BP)neural networks,the solution is simplified and can be solved in real-time.Simulation and experiments were carried out on the SR4 parallel robot.The results show that the proposed method improves the efficiency,smoothness,and stability of the robot.This paper proposes an online trajectory planning method which is velocity constraints based and can improve the efficiency and stability of high-speed parallel robots.The work of this research is conducive to finely applying high-speed parallel robots.
基金supported in part by the National Natural Science Foundation of China under Grant 52022040in part by the Postgraduate Research&Practice Innovation Program of NUAA。
文摘For permanent magnet linear synchronous motor(PMLSM) working at trapezoidal speed for long time, high thrust brings high temperature rise, while low thrust limits dynamic performance. Thus, it is crucial to find a balance between temperature rise and dynamic performance. In this paper, a velocity planning model of the PMLSM at trapezoidal speed based on electromagnetic-fluid-thermal(EFT) field is proposed to obtain the optimal dynamic performance under temperature limitation. In this model, the winding loss is calculated considering the acceleration and deceleration time. The loss model is indirectly verified by the temperature rise experiment of an annular winding sample. The actual working conditions of the PMLSM are simulated by dynamic grid technology to research the influence of acceleration and deceleration on fluid flow in the air gap, and the variation rule of the thermal boundary condition is analyzed. Combined with the above conditions, the temperature rise of a coreless PMLSM(CPMLSM) under the rated working condition is calculated and analyzed in detail. Through this method and several iterations, the optimal dynamic performance under the temperature limitation is achieved. The result is verified by a comparison between simulation and prototype tests, which can help improve the dynamic performance.
基金Supported by Jiangsu Provincial Key R&D Program(Grant No.BE2019004)National Natural Science Funds for Distinguished Young Scholar of China(Grant No.52025121)+1 种基金National Nature Science Foundation of China(Grant Nos.51805081,51975118,52002066)Jiangsu Provincial Achievement Transformation Project(Grant No.BA2018023).
文摘Most researches focus on the regenerative braking system design in vehicle components control and braking torque distribution,few combine the connected vehicle technologies into braking velocity planning.If the braking intention is accessed by the vehicle-to-everything communication,the electric vehicles(EVs)could plan the braking velocity for recovering more vehicle kinetic energy.Therefore,this paper presents an energy-optimal braking strategy(EOBS)to improve the energy efficiency of EVs with the consideration of shared braking intention.First,a double-layer control scheme is formulated.In the upper-layer,an energy-optimal braking problem with accessed braking intention is formulated and solved by the distance-based dynamic programming algorithm,which could derive the energy-optimal braking trajectory.In the lower-layer,the nonlinear time-varying vehicle longitudinal dynamics is transformed to the linear time-varying system,then an efficient model predictive controller is designed and solved by quadratic programming algorithm to track the original energy-optimal braking trajectory while ensuring braking comfort and safety.Several simulations are conducted by jointing MATLAB and CarSim,the results demonstrated the proposed EOBS achieves prominent regeneration energy improvement than the regular constant deceleration braking strategy.Finally,the energy-optimal braking mechanism of EVs is investigated based on the analysis of braking deceleration,battery charging power,and motor efficiency,which could be a guide to real-time control.
基金Supported by National Key R&D Program of China(Grant No.2017YFB0309800)National Natural Science Foundation of China(Grant No.51405445)
文摘Sharp corners usually are used on glass contours to meet the highly increasing demand for personalized products,but they result in a broken wheel center toolpath in edge grinding.To ensure that the whole wheel center toolpath is of G1 continuity and that the grinding depth is controllable at the corners,a transition toolpath generation method based on a velocity-blending algorithm is proposed.Taking the grinding depth into consideration,the sharp-corner grinding process is planned,and a velocity-blending algorithm is introduced.With the constraints,such as traverse displacement and grinding depth,the sharp-corner transition toolpath is generated with a three-phase motion arrangement and with confirmations of the acceleration/deceleration positions.A piece of glass with three sharp corners is ground on a three-axis numerical-control glass grinding equipment.The experimental results demonstrate that the proposed algorithm can protect the sharp corners from breakage efficiently and achieve satisfactory shape accuracy.This research proposed a toolpath generation method based on a velocity-blending algorithm for the manufacturing of personalized glass products,which generates the transition toolpath as needed around a sharp corner in real time.
文摘In order to satisfy the high efficiency and high precision of collaborative robots,this work presents a novel trajectory planning method.First,in Cartesian space,a novel velocity look-ahead control algorithm and a cubic polynomial are combined to construct the end-effector trajectory of robots.Then,the joint trajectories can be obtained through the inverse kinematics.In order to improve the smoothness and stability in joint space,the joint trajectories are further adjusted based on the velocity look-ahead control algorithm and quintic B-spline.Finally,the proposed trajectory planning method is tested on a 4-DOF serial collaborative robot.The experimental results indicate that the collaborative robot achieves the high efficiency and high precision,which validates the effectiveness of the proposed method.
基金supported by National Natural Science Foundation of China (Grant Nos. 61035005,61075087)Hubei Provincial Natural Science Foundation of China (Grant No. 2010CDA005)Hubei Provincial Education Department Foundation of China (Grant No.Q20111105)
文摘Path planning for space vehicles is still a challenging problem although considerable progress has been made over the past decades.The major difficulties are that most of existing methods only adapt to static environment instead of dynamic one,and also can not solve the inherent constraints arising from the robot body and the exterior environment.To address these difficulties,this research aims to provide a feasible trajectory based on quadratic programming(QP) for path planning in three-dimensional space where an autonomous vehicle is requested to pursue a target while avoiding static or dynamic obstacles.First,the objective function is derived from the pursuit task which is defined in terms of the relative distance to the target,as well as the angle between the velocity and the position in the relative velocity coordinates(RVCs).The optimization is in quadratic polynomial form according to QP formulation.Then,the avoidance task is modeled with linear constraints in RVCs.Some other constraints,such as kinematics,dynamics,and sensor range,are included.Last,simulations with typical multiple obstacles are carried out,including in static and dynamic environments and one of human-in-the-loop.The results indicate that the optimal trajectories of the autonomous robot in three-dimensional space satisfy the required performances.Therefore,the QP model proposed in this paper not only adapts to dynamic environment with uncertainty,but also can satisfy all kinds of constraints,and it provides an efficient approach to solve the problems of path planning in three-dimensional space.