关节型机械臂高承载轨迹规划方法研究

针对关节型机械臂普遍具有负载自重比低的问题,提出了两种提高机械臂承载能力的轨迹规划方法。第一种为轨迹生成法,将运动过程分段,借助正确的动力学模型选取每段运动过程中的关节加速度值,然后,将所有的加速度值进行组合,生成一组力矩平滑的运动轨迹,避免了运动过程中出现过大的关节力矩峰值。第二种为轨迹优化法,预先选取一种标准预定义运动曲线作为运动轨迹,使用遗传算法优化运动曲线的参数,将机械臂的关节力矩峰值降到最低,同样避免了出现过大的关节力矩峰值。经过Adams仿真发现,相比于其他常用的各种轨迹规划方法,这两种方法明显提高了机械臂的承载能力。最后,通过实验,验证了所述方法的正确性与有效性。

Cooperative merging control strategy of connected and automated vehicles on highways

To improve traffic performance when on-ramp vehicles merge into the mainstream,a collaborative merging control strategy is proposed to determine the merging sequence and trajectory control of vehicles.Merging trajectory planning takes the minimization of vehicle acceleration as the optimization objective.Either the variational method or the quadratic programming method is utilized to determine arrival time,optimal time and control variables for each vehicle.As a supplement,the adaptive cruise control(ACC)model is used to calculate each control variable in each time interval on special occasions.Simulation results show that the cooperative merging control strategy outperforms the optimal control strategy.The root mean square(RMS)of acceleration and the root mean square error(RMSE)of time headway are significantly decreased,with the reductions up to 90.1%and 25.2%,respectively.Under the cooperative control strategy,the difference between the average speed and desired speed consistently approaches zero.In addition,few or no collisions occur.To conclude,the proposed strategy favours the improvements in passenger comfort,traffic efficiency,traffic stability and safety around highway on-ramps.

An Improved United Trajectory Optimization Approach in Boost-phase Considering Attitude Control Ability

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,

A survey of numerical algorithms for trajectory optimization of flight vehicles

As one of the important components of computational flight mechanics and control,numerical algorithms of trajectory optimization for flight vehicles are currently studied by many researchers in aerospace engineering to completely solve these difficult problems,but few papers on the survey of this research field have been published recently.Based on the investigation of more than one hundred literatures,considering the application perspectives of computational flight mechanics and recent developments of trajectory optimization,the numerical algorithms of trajectory optimizations for aerospace vehicles are summarized and systematically analyzed.This paper summarized the basic principle,characteristics and application for all kinds of current trajectory optimization algorithms;and introduced some new methods and theories appearing in recent years.Finally,collaborative trajectory optimization for many flight vehicles,and hypersonic vehicle trajectory optimization were mainly reviewed in this paper.In the conclusion of this paper,the future research properties are presented regarding to numerical algorithms of trajectory optimization and control for flight vehicles as follows:collaboration and antagonization for many flight vehicles and multiple targets,global,real-time online,high accuracy of 7-D trajectory,considering all kinds of unknown random disturbances in trajectory optimization,and so on.

Robust optimization of nonlinear impulsive rendezvous with uncertainty

The optimal rendezvous trajectory designs in many current research efforts do not incorporate the practical uncertainties into the closed loop of the design.A robust optimization design method for a nonlinear rendezvous trajectory with uncertainty is proposed in this paper.One performance index related to the variances of the terminal state error is termed the robustness performance index,and a two-objective optimization model(including the minimum characteristic velocity and the minimum robustness performance index)is formulated on the basis of the Lambert algorithm.A multi-objective,non-dominated sorting genetic algorithm is employed to obtain the Pareto optimal solution set.It is shown that the proposed approach can be used to quickly obtain several inherent principles of the rendezvous trajectory by taking practical errors into account.Furthermore,this approach can identify the most preferable design space in which a specific solution for the actual application of the rendezvous control should be chosen.