基于目前新近提出的离散机械最优控制(Discrete Mechanics and Optimal Control)算法针对水下机器人的路径规划进行了仿真研究,设计的轨迹的轨迹经仿真实验能够按照能量或者最优的路径对设定的障碍进行有效避让。证明此算法能够有较强...基于目前新近提出的离散机械最优控制(Discrete Mechanics and Optimal Control)算法针对水下机器人的路径规划进行了仿真研究,设计的轨迹的轨迹经仿真实验能够按照能量或者最优的路径对设定的障碍进行有效避让。证明此算法能够有较强的实用性。同时文章涉及的理论算法为进一应用到其它类似机械装置,比如无人飞行器,机器人的路径规划与控制提供了一种新的方法思路。展开更多
A general approach for controlling of periodical dynamic systems was presented by taking robotic yoyo as an example. The height of the robot arm when the yoyo arrives at the bottom was chosen as virtual control. The i...A general approach for controlling of periodical dynamic systems was presented by taking robotic yoyo as an example. The height of the robot arm when the yoyo arrives at the bottom was chosen as virtual control. The initial amplitude of yoyo could be mapped to the desired final amplitude by adjusting the virtual control. First,the yoyo motion was formulated into a nonlinear optimal control problem which contained the virtual control. The reference trajectory of robot could be obtained by solving the optimal problem with analytic method or more general numerical approach. Then,both PI and deadbeat control methods were used to control the yoyo system. The simulation results show that the analytic solution of the reference trajectory is identical to the numerical solution,which mutually validates the correctness of the two solution methods. In simulation,the initial amplitude of yoyo is set to be 0.22 m which is 10% higher than the desired final amplitude of 0.2 m. It can be seen that the amplitude achieves the desired value asymptotically in about five periods when using PI control,while it needs only one period with deadbeat control. The reference trajectory of robot is generated by optimizing a certain performance index; therefore,it is globally optimal. This is essentially different from those traditional control methods,in which the reference trajectories are empirically imposed on robot. What's more,by choosing the height of the robot arm when the yoyo arrives at the bottom as the virtual control,the motion of the robot arm may not be out of its stroke limitation. The proposed approach may also be used in the control of other similar periodical dynamic systems.展开更多
This paper covers the hicles. Different from the traditional trajectory optimization design problem ＂once downward＂ movement principle of a class of demonstration flight test ve of negative attack angle, the ＂twice...This paper covers the hicles. Different from the traditional trajectory optimization design problem ＂once downward＂ movement principle of a class of demonstration flight test ve of negative attack angle, the ＂twice down ward＂ lower trajectory is proposed based on a SOP algorithm to meet the requirement for validating thermal protec- tion materials, Furthermore, an important advantage of this presented method, compared to the traditional method, is that both trajectory constraints and attitude control constraints are considered. An engineering example is also given to show the advantage and effectiveness of this method,展开更多
Significant propellant mass saving can be obtained with the use of complex multiple intermediate flyby maneuvers for conventional propulsion systems,and trip time also decreases for a portion of the proper solar sail ...Significant propellant mass saving can be obtained with the use of complex multiple intermediate flyby maneuvers for conventional propulsion systems,and trip time also decreases for a portion of the proper solar sail missions.This paper discusses the performance of gravity assist(GA)in the time-optimal control problem of solar sailing with respect to sail lightness number and the energy difference between the initial and final orbit in the rendezvous problem in a two-body model,in which the GA is modeled as a substantial change in the velocity of the sailcraft at the GA time.In addition,this paper presents a method to solve the time-optimal problem of solar sailing with GA in a full ephemeris model,which introduces the third body’s gravity in a dynamic equation.This study builds a set of inner constraints that can describe the GA process accurately.Finally,this study presents an example for evaluating the accuracy and rationality of the two-body model’s simplification of GA by comparison with the full ephemeris model.展开更多
文摘基于目前新近提出的离散机械最优控制(Discrete Mechanics and Optimal Control)算法针对水下机器人的路径规划进行了仿真研究,设计的轨迹的轨迹经仿真实验能够按照能量或者最优的路径对设定的障碍进行有效避让。证明此算法能够有较强的实用性。同时文章涉及的理论算法为进一应用到其它类似机械装置,比如无人飞行器,机器人的路径规划与控制提供了一种新的方法思路。
基金Project(50475025) supported by the National Natural Science Foundation of China
文摘A general approach for controlling of periodical dynamic systems was presented by taking robotic yoyo as an example. The height of the robot arm when the yoyo arrives at the bottom was chosen as virtual control. The initial amplitude of yoyo could be mapped to the desired final amplitude by adjusting the virtual control. First,the yoyo motion was formulated into a nonlinear optimal control problem which contained the virtual control. The reference trajectory of robot could be obtained by solving the optimal problem with analytic method or more general numerical approach. Then,both PI and deadbeat control methods were used to control the yoyo system. The simulation results show that the analytic solution of the reference trajectory is identical to the numerical solution,which mutually validates the correctness of the two solution methods. In simulation,the initial amplitude of yoyo is set to be 0.22 m which is 10% higher than the desired final amplitude of 0.2 m. It can be seen that the amplitude achieves the desired value asymptotically in about five periods when using PI control,while it needs only one period with deadbeat control. The reference trajectory of robot is generated by optimizing a certain performance index; therefore,it is globally optimal. This is essentially different from those traditional control methods,in which the reference trajectories are empirically imposed on robot. What's more,by choosing the height of the robot arm when the yoyo arrives at the bottom as the virtual control,the motion of the robot arm may not be out of its stroke limitation. The proposed approach may also be used in the control of other similar periodical dynamic systems.
文摘This paper covers the hicles. Different from the traditional trajectory optimization design problem ＂once downward＂ movement principle of a class of demonstration flight test ve of negative attack angle, the ＂twice down ward＂ lower trajectory is proposed based on a SOP algorithm to meet the requirement for validating thermal protec- tion materials, Furthermore, an important advantage of this presented method, compared to the traditional method, is that both trajectory constraints and attitude control constraints are considered. An engineering example is also given to show the advantage and effectiveness of this method,
文摘Significant propellant mass saving can be obtained with the use of complex multiple intermediate flyby maneuvers for conventional propulsion systems,and trip time also decreases for a portion of the proper solar sail missions.This paper discusses the performance of gravity assist(GA)in the time-optimal control problem of solar sailing with respect to sail lightness number and the energy difference between the initial and final orbit in the rendezvous problem in a two-body model,in which the GA is modeled as a substantial change in the velocity of the sailcraft at the GA time.In addition,this paper presents a method to solve the time-optimal problem of solar sailing with GA in a full ephemeris model,which introduces the third body’s gravity in a dynamic equation.This study builds a set of inner constraints that can describe the GA process accurately.Finally,this study presents an example for evaluating the accuracy and rationality of the two-body model’s simplification of GA by comparison with the full ephemeris model.
