基于动力学不确定性的视觉伺服机器人控制

针对视觉伺服机器人系统中存在的动力学不确定性的问题,提出了一种基于动态补偿与摩擦力补偿的自适应鲁棒控制方案。该方案创新性在于将图像平面上的输出信号反馈至关节空间,结合动力学模型的参数线性化性质设计自适应算法在线标定不确定的动力学参数,同时无需测量摩擦力,通过设计自适应鲁棒项在线预估摩擦力。通过李亚普洛夫稳定性分析工具能证明提出的控制方案可以全局镇定闭环系统,同时实现精确的图像轨迹跟踪。仿真结果表明了所提出的自适应鲁棒控制方法的有效性。

一类具有多种不确定性机器人系统的自适应控制

机器人系统含有不同类型的不确定性因素,这些因素的存在可能会影响系统的控制精度,甚至引起系统不稳定。针对具有外部干扰、内部动力学参数不确定性以及未知死区特性的一类不确定性机器人系统,提出了一种基于干扰观测器的自适应控制器。首先建立具有外部干扰的机器人系统非线性数学模型,并对模型中内部动力学参数不确定性和未知死区特性进行了分析。采用非线性干扰观测器对系统所受到的外部干扰进行估计和补偿,在干扰观测器的基础上设计自适应控制器用来处理内部动力学参数的不确定性以及未知的死区特性。最后采用李雅谱诺夫函数法从理论上证明了系统的稳定性和位置跟踪误差的收敛性,并采用数值仿真验证了所设计方法的有效性。

参数不确定性遥操作系统的自适应同步控制

已有的遥操作自适应控制方案缺乏对系统中主-从机器人运动学参数不确定的考虑。针对同时具有动力学和运动学参数不确定性的遥操作系统,提出了一种逆动力学自适应控制方法,并利用Lyapunov函数法对系统的稳定性和位置同步性能进行了论证,最后通过仿真进行了验证。该方法在两类参数都无法精确获知的情况下,仍然可以取得主-从机器人的位置轨迹同步。该方法还可以获得线性解耦的闭环误差方程,便于对系统透明性进行分析。

未标定视觉伺服系统的动力学控制

针对具有动力学不确定性的未标定机器人视觉伺服系统,通过在机器人末端操作器上选取多个特征点,设计了一个基于机器人动力学的关节力矩控制器,使得特征点在图像平面上收敛到其期望值.首先,分别基于不含深度信息的图像雅可比矩阵和一组适当选取的机器人动力学参数,建立了摄像机和机器人动力学的线性参数模型.然后,在此基础上,进一步设计了摄像机和机器人动力学参数的在线自适应更新律,分析了系统的稳定性.最后,在一个三关节机械臂上进行了仿真实验,实验结果验证了该控制方案的良好控制效果.

2R1T并联机构的滑模控制与轨迹跟踪方法

针对并联机构存在建模误差和实际工作时会受到外界干扰的问题,设计了一种改进型的终端积分滑模控制方法(MTISMC),以提高并联机构的跟踪精度和跟踪误差快速收敛到零的性能。该方法基于跟踪误差设计改进型的PID滑模面,结合并联机构的不确定性动力学模型,设计出新型的终端积分滑模控制方法;并基于Lyapunov稳定性对该控制方法进行了稳定性分析。最后仿真结果表明,MTISMC控制方法跟踪误差的均方根均小于PID和TISMC控制方法,具有更高的跟踪精度和更强的鲁棒性。

直接驱动机器人自适应-PD复合运动控制研究

针对直接驱动机器人结构参数与摩擦参数的非确定性，提出机器人自适应-PD控制策略。首先分析了机器人的两类不确定性，推演了机器人动力学方程，给出不确定性动力学结构量的线性化表示；然后，对关节摩擦力矩矢进行了建模；为补偿动力学不确定性给机器人带来的控制误差，构建含位置与速度反馈的双闭环控制系统，引入自适应机构辨识不确定性参量，并据此规划出自适应控制律；为提高运动控制精度，在控制器中嵌入PD子控制器。仿真实验显示，系统的位置和角速度跟踪误差分别为-0.02°-0.03°与±0.005rad/s，表明自适应-PD控制律可实现直接驱动机器人精密轨迹控制。

Dynamic analysis and experimental study of vibro-acoustic system with uncertainties at middle frequencies

To take into account the influence of uncetainties on the dynamic response of the vibro-acousitc structure, a hybrid modeling technique combining the finite element method（FE）and the statistic energy analysis（SEA） is proposed to analyze vibro-acoustics responses with uncertainties at middle frequencies. The mid-frequency dynamic response of the framework-plate structure with uncertainties is studied based on the hybrid FE-SEA method and the Monte Carlo（MC）simulation is performed so as to provide a benchmark comparison with the hybrid method. The energy response of the framework-plate structure matches well with the MC simulation results, which validates the effectiveness of the hybrid FE-SEA method considering both the complexity of the vibro-acoustic structure and the uncertainties in mid-frequency vibro-acousitc analysis. Based on the hybrid method, a vibroacoustic model of a construction machinery cab with random properties is established, and the excitations of the model are measured by experiments. The responses of the sound pressure level of the cab and the vibration power spectrum density of the front windscreen are calculated and compared with those of the experiment. At middle frequencies, the results have a good consistency with the tests and the prediction error is less than 3. 5dB.

Study on the Cause and Dynamics of Seawater Intrusion in Laizhou Bay

In this paper, we conduct research on the cause and dynamics of seawater intrusion in the Laizhou bay. To consider modelling the Laizhou bay, we should then take the listed tools into consideration. In actual engineering, wave is a complicated stochastic process. If the numerical value of wave model is a little too large, the wave attenuation should be considered sufficiently, such as wave refraction caused by terrain change, wave attenuation due to submarine friction, wave into the very shallow waters of the broken and small wind area. We integrate the current conition of the Laizhou bay and the further model the seawater intrusion steps. The uncertainty research of ground water solute migration is at present a ground water research area quite popular topic, but the seawater intrusion is the variable density class solute migration issue, applies the uncertainty analysis of seawater intrusion simulation also to have certain difficulty the existing research results. In the future, more simulation will be down to verify the effectiveness.

Discussion of skill improvement in marine ecosystem dynamic models based on parameter optimization and skill assessment

Marine ecosystem dynamic models(MEDMs) are important tools for the simulation and prediction of marine ecosystems. This article summarizes the methods and strategies used for the improvement and assessment of MEDM skill, and it attempts to establish a technical framework to inspire further ideas concerning MEDM skill improvement. The skill of MEDMs can be improved by parameter optimization(PO), which is an important step in model calibration. An effi cient approach to solve the problem of PO constrained by MEDMs is the global treatment of both sensitivity analysis and PO. Model validation is an essential step following PO, which validates the effi ciency of model calibration by analyzing and estimating the goodness-of-fi t of the optimized model. Additionally, by focusing on the degree of impact of various factors on model skill, model uncertainty analysis can supply model users with a quantitative assessment of model confi dence. Research on MEDMs is ongoing; however, improvement in model skill still lacks global treatments and its assessment is not integrated. Thus, the predictive performance of MEDMs is not strong and model uncertainties lack quantitative descriptions, limiting their application. Therefore, a large number of case studies concerning model skill should be performed to promote the development of a scientifi c and normative technical framework for the improvement of MEDM skill.

Quaternion-based robust trajectory tracking control for uncertain quadrotors

This paper presents a robust nonlinear controller design approach for uncertain quadrotors to implement trajectory tracking missions. The quaternion representation is applied to describe the rotational dynamics in order to avoid the singularity problem existing in the Euler angle representation. A nonlinear robust controller is proposed, which consists of an attitude controller to stabilize the rotational motions and a position controller to control translational motions. The quadrotor dynamics involves uncertainties such as parameter uncertainties, nonlinearities, and external disturbances and their effects on closed-loop control system can be guaranteed to be restrained. Simulation results on the quadrotor demonstrate the effectiveness of the designed control approach.

Revisiting the Twist-3 Distribution Amplitudes of K Meson Within the QCD Background Field Approach

In the present paper, we investigate the kaon twist-3 distribution amplitudes （DAs）Cp within the QCD background field approach. The SUf （3）-breaking effects are studied in detail under a systematical way, especiaJ1y the sum rules for the moments of are obtained by keeping all the mass terms in the s-quark propagator consistently. After adding all the uncertainties in quadrature, the first two Gegenbauler moments of are a GeV. A detailed discussion on the properties tion parameters moments shows that the higher-order s-quark mass terms can indeed provide sizable contributions. Fhrthermore, based on the newly obtained moments, a model for the kaon twist-3 wavefunction with a better end-point behavior is constructed, which shall be useful for perturbative QCD calculations. As a byproduct, we make a discussion on the properties of the pion twist-3 DAs.