融合KCCA推断强化学习的机器人智能轨迹规划

针对当前模仿强化学习(LfDRL)框架面向新任务时并未考虑机器人各关节之间的联系,从而影响学习效果的不足,利用伪协方差矩阵的思想,基于再生核空间(RKHS)和广义瑞丽熵构建面向泛函指标的关节间摄动相关局部坐标系,进而设计出一种集成核典型相关分析(KCCA)与路径积分策略提升(PI~2)的强化学习方法.利用学习经验数据基于KCCA推断出机器人各关节间面向轨迹规划任务的隐含非线性启发式信息,引导PI~2搜索到最优/次优策略,使得机器人实现从示范轨迹规划任务到新轨迹规划任务的快速迁移学习,并高质量完成.选择顺应性装配机械手臂(SCARA)和优傲5(UR5)机器人的过单点、过两点迁移学习智能轨迹规划实验,结果表明:融合KCCA推断启发式信息的强化学习的平均代价下降率明显优于经典的PI~2算法,其机器人智能轨迹规划在提升学习收敛速度的同时也提高了机器人完成新任务的精度.     

基于DMPs的双机器人协同搬运轨迹的学习与泛化

针对双机器人协作系统执行具有强协调约束关系的仿人任务时,存在轨迹学习复杂、协调约束分析欠缺的问题,提出了基于动态运动基元（DMPs）的双机器人协同搬运轨迹学习及泛化方法。首先,从双机器人协同搬运任务出发,分析了双机器人协调约束关系,建立了双机器人运动约束模型。然后,将机器人运动轨迹解耦为位置轨迹和姿态轨迹,采用四元数实现姿态轨迹的无奇异描述,分别建立位置轨迹和姿态轨迹的动态运动基元模型,结合双机器人运动约束模型与动态运动基元模型,兼顾各自的任务要求和相对位姿约束,进而获得双机器人的运动轨迹。接着,开展了双机器人协同搬运轨迹的仿真与实验,结果表明：采用双机器人协同搬运轨迹的学习与泛化方法,当改变起、终点状态时,双机器人定姿态协同搬运的起、终点位置误差分别为0.029 2 mm和0.112 7 mm,变姿态协同搬运的起、终点位置误差分别为0.032 3 mm和0.113 1 mm,终点的四元数姿态偏差为0.001 4、0.002 7、0.001 8、0.003 0,表明该协同搬运轨迹的学习与泛化方法具有较高的运动控制精度,即使起、终点任务参数改变,泛化轨迹仍可保证目标的可达性,验证了提出的...     

基于双空间交替学习的机器人运动技能获取

针对如何基于示范任务学习让机器人自主获得完成新任务的能力的难题,提出一种高斯混合回归结合路径积分策略提升(GMR-PI2)的表达、模仿和优化框架,同时采用基函数、策略表达权系数两个空间上交替搜索执行方案来解决上述问题.核心思想是当权系数探索到最佳逼近点附近时,根据经验最优轨迹集进行基函数的自重组,然后再重启权系数搜索,从而实现从示范任务到指标集约束任务的渐进运动技能获取.经典的轨迹规划过点实验结果表明该方法是有效和可行的.     

基于ROS的移动机器人导航系统研究与仿真

针对移动机器人的自主环境感知与自主导航问题,本文提出了一种基于机器人操作系统(ROS),并结合同步定位与地图构建技术(SLAM)与路径规划的多目标点导航方式。首先利用GAZEBO仿真平台建立基于阿克曼结构的四轮机器人和仿真环境。然后利用SLAM技术,构建仿真环境的二维栅格地图。最后利用多目标点导航算法,开展机器人针对多个目标区域的自主导航测试。并通过调整TEB参数,优化机器人的运动轨迹。实验结果表明:机器人有效完成了多个目标区域的自主导航任务,并且规划路径较为合理,运行过程较为平稳。     

基于深度强化学习的水下机器人最优轨迹控制

为了实现水下机器人在跟踪复杂轨迹时具有出较高的精度和稳定性,提出了利用深度强化学习实现水下机器人最优轨迹控制的方法:首先,建立基于2个深度神经网络（Actor网络和Critic网络）的水下机器人控制模型,其中Actor网络用来选择动作,Critic网络用来评估Actor网络的训练结果;其次,构造合适的奖励信号使得深度强化学习算法适用于水下机器人的动力学模型;最后,提出了基于奖励信号标准差的网络训练成功评判条件,使得水下机器人在确保精度的同时保证稳定性. 仿真实验结果表明:在解决一定精度内的水下机器人复杂轨迹跟踪问题时,该算法与传统PID控制算法相比具有更优的性能.     

空中机器人(UAV)轨迹规划设计与仿真

研究空中机器人(UAV)的轨迹规划,使空中机器人(UAV)可以在顺利躲避障碍物的前提下从初始点到目标点。通过对空中机器人(UAV)的轨迹环境采用栅格化处理,在基于栅格划归的轨迹环境下运用蚁群算法寻求空中机器人(UAV)从初始点到目标点的最短路径,并在MATLAB中进行轨迹仿真。经过轨迹仿真,可以明显证明基于蚁群算法的空中机器人(UAV)可以寻求一条从初始点到目标点的最短路径。     

基于迭代学习控制算法的下肢外骨骼机器人跟随特性研究

目前下肢外骨骼机器人存在的运动控制算法追踪人体髋关节和膝关节期望轨迹时存在误差,从而导致人机系统随动性能差。因此,本文提出迭代学习控制算法追踪人体髋关节和膝关节期望轨迹。首先,结合人体下肢结构分析,建立下肢外骨骼机器人动力学模型;其次,基于迭代学习控制算法建立下肢外骨骼机器人随动控制模型;最后,利用Matlab软件设计指数变增益闭环D型运动控制系统,分析收敛速度与谱半径的关系,追踪得到人体下肢髋关节和膝关节期望轨迹。仿真结果表明该算法能够有效提高下肢外骨骼机器人步态轨迹跟踪精度,提升人机系统随动性能。     

基于费拉里法的Delta机器人动态目标抓取算法

针对Delta并联机器人难以在运动环境下有效分拣动态目标的问题,提出了基于费拉里法的动态目标抓取算法.首先,利用3-4-5次多项式运动规律进行了轨迹规划,并对轨迹的不同情况进行了分析.然后,对运动环境下的目标抓取问题建立了数学模型,并针对该数学模型提出了基于费拉里法的动态目标抓取算法.算法测试结果表明:该算法能精准地计算抓取位置,速度快,能满足实时性要求,且无须设置初值,使用便捷.样机实验结果表明:利用该算法能使Delta机器人以90次/min的速度进行动态目标抓取,证明了算法的准确性与稳定性.     

基于粒子群算法的可重构模块化机器人速度约束下轨迹规划

针对可重构模块化机器人速度约束下的时间最优轨迹规划进行研究.首先利用旋量理论实现模块化机器人运动学方程的自动生成,并在此基础上利用3-5-3多项式插值进行机器人的轨迹规划.由于可重构模块化机器人系统刚性差、在高速运动时会产生较大振动,需要对运动速度进行约束,本文利用粒子群算法对速度约束下的插值时间进行优化,使得机器人在速度限制下实现运行时间最优.最后通过仿真实验得到机器人角度、加速度以及角加速度曲线并进行分析,证明了方法能有效地实现速度约束下的最优轨迹规划.     

基于非刚性点云配准的运动鞋鞋帮打磨轨迹提取

为了解决冷黏运动鞋自动化生产过程中鞋帮打磨轨迹难以提取的问题，提出一种利用非刚性点云配准算法提取轨迹的方法。搭建三维视觉平台分别获取鞋底侧墙与鞋帮点云，基于高斯混合模型，结合运动相干性和先验分布构建了鞋底与鞋帮点云配准概率的联合概率密度分布，并采用变分贝叶斯推断计算出最佳配准参数，进而实现两种点云间的精确配准。对配准后的点云提取边缘轨迹并聚类分割，提取的边缘轨迹即为鞋帮打磨轨迹。研究证明，该方法可有效提取运动鞋的鞋帮打磨轨迹曲线，相比依靠离线采样点提取打磨轨迹的传统方法，可大幅缩减轨迹的获取时间且精度良好。     

可重构四足机器人的结构设计与协同导航算法

可重构足式机器人作为移动机器人的一个重要分支,具有承载能力好、运动灵活、适应性强等特点。综合变胞Metamorphic理论和机器人驱动技术,设计一种自由切换形态的足式机器人,可广泛应用于校园、工厂等复杂场景的物流工作。提出不同形态间的切换方案,针对倾覆后的翻身动作提出对应的方案,可以适应复杂的任务。设计场景中包含动态行人的协同导航算法,采用时空-图注意力神经网络对机器人节点和行人节点进行建模,并从历史轨迹中提取出行人和机器人的潜在特征,通过实验验证算法的可行性,实验结果证明了该算法具有更好的行人未来轨迹预测能力。     

基于A~*算法的机器人二维与三维路径规划实现

主要对移动机器人轨迹进行规划设计,将移动机器人的轨迹环境采用栅格化处理,提出了一种能结合全局和局部规划的改进的A*算法。使移动机器人在环境未知的情况下进行自主规划路径,通过MATLAB软件验证了算法的可实现性与稳定性,并将其与经典A*算法作对比,以证明改进算法的在运算能力,可实现性和稳定性上的优势。     

Learning of action through adaptive combination of motor primitives

Understanding how the brain constructs movements remains a fundamental challenge in neuroscience. The brain may control complex movements through flexible combination of motor primitives, where each primitive is an element of computation in the sensorimotor map that transforms desired limb trajectories into motor commands. Theoretical studies have shown that a system's ability to learn action depends on the shape of its primitives. Using a time-series analysis of error patterns, here we show that humans learn the dynamics of reaching movements through a flexible combination of primitives that have gaussian-like tuning functions encoding hand velocity. The wide tuning of the inferred primitives predicts limitations on the brain's ability to represent viscous dynamics. We find close agreement between the predicted limitations and the subjects' adaptation to new force fields. The mathematical properties of the derived primitives resemble the tuning curves of Purkinje cells in the cerebellum. The activity of these cells may encode primitives that underlie the learning of dynamics.     

Phosphatidylglycerol effect on oxygen-evolving activity in Ca2+-depleted photosystem II

The effect of anionic phosphatidylglycerol (PG) on oxygen evolution in a photosystem II (PS II ) particle depleted of Ca²⁺ (designated d_CaPSII ) has been investigated. The major finding is the observation of a new role of PG in the PSII function. That is, PG restores nearly the lost oxygen evolution in d_caPS II particle owing to Ca²⁺ depletion to the levels in intact PS II. Furthermore, there is a stimulation of oxygen-evolving activity in the d_CaPSII complexed with PG in the presence of exogenous CaCl₂, which PG enhances increasingly oxygen evolution with increasing CaCl₂ concentration. It is suggested that PG-induced oxygen evolution recovery of d_Ca PS II particle results from resumption of normal structure in protein by PG effect, whereas the enhancement of oxygen evolution in complex subject to CaCl₂ is ascribed to the optimization of such a structure due to coordination complex formation of Ca²⁺ ions with PG.     

一种新的力—位混控机器人工作任务描述方法

影响力－位置混合控制和机器人人工业应用的主要障碍之一,在于其工作任务的描述复杂,对使用人员的要求比较高,本文提出了一种新的工作任务描述方法,该方法建立在机器人的微运动描述之上,使描述工作由获得控制参数变成分析微运动组成,大大降低了任务描述难度,可使操作者较方便地描述机器人的工作任务。     

Real-time prediction of hand trajectory by ensembles of cortical neurons in primates

Signals derived from the rat motor cortex can be used for controlling one-dimensional movements of a robot arm. It remains unknown, however, whether real-time processing of cortical signals can be employed to reproduce, in a robotic device, the kind of complex arm movements used by primates to reach objects in space. Here we recorded the simultaneous activity of large populations of neurons, distributed in the premotor, primary motor and posterior parietal cortical areas, as non-human primates performed two distinct motor tasks. Accurate real-time predictions of one- and three-dimensional arm movement trajectories were obtained by applying both linear and nonlinear algorithms to cortical neuronal ensemble activity recorded from each animal. In addition, cortically derived signals were successfully used for real-time control of robotic devices, both locally and through the Internet. These results suggest that long-term control of complex prosthetic robot arm movements can be achieved by simple real-time transformations of neuronal population signals derived from multiple cortical areas in primates.     

Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning,China:New 40Ar÷39Ar dating of the Yixian and Tuchengzi Formations

We report new ⁴⁰Ar÷³⁹Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion ⁴⁰Ar÷³⁹Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion ⁴⁰Ar÷³⁹Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca÷K ratios, excellent reproducibility and gave a mean age of 125.0±0.18 (1SD)±0.04 (SE) Ma. Single sanidine crystal total fusion ⁴⁰Ar÷³⁹Ar analyses of the Hengdaozi tuff gave a mean age of 125.0±0.19 (1SD)±0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4±0.19 (1SD)±0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.     

The new sideway of CNTF signal transduction pathway

The action of ciliary neurotrophic factor (CNTF) on intercellular free Ca²⁺ concentrations [Ca²⁺]_i induced by glutamate (Glu) in primary cultured hippocampal neurons were detected with Fura2/AM, a Ca²⁺-sensitive fluorophore, and the morphological influence of G-protein on it was objected. Glu could induce rapid increase of [Ca²⁺]_i in hippocampal neurons. CNTF had no significant action on [Ca²⁺]_i in resting hippocampal neurons. However, after incubation of CNTF for 5 min, the increase of [Ca²⁺]_i in hippocampal neurons rapidly induced by Glu was inhibited. Pretussis toxin (PTX)-sensitive G protein could block the action. These results indicate that a new non-genomic rapid sideway might exist in the upper stream of CNTF signal transduction pathway, which was related to Ca²⁺ signal transduction. Keywords:     

Rearrangements of microtubule cytoskeleton in stomatal closure of <Emphasis Type="Italic">Arabidopsis</Emphasis> induced by nitric oxide

NO （nitric oxide）, known as a key signal molecule in plant, plays important roles in regulation of stomatal movement. In this study, microtubule dynamics and its possible mechanism in the NO signal pathway were investigated. The results were as follows： （i） In vivo stomatsl aperture assays revealed that both vinblastine （microtubule-disrupUng drug） and SNP （exogenous NO donor） prevented stomatsl opening in the light, and vinblastine even could enhance the inhibitory effect of SNP, whereas tsxol （a microtubule-stsbilizing agent） was able to reduce this effect; （ii） microtubules in the opening Arabi-dopsis guard cells expressing GFP：a-tubulin-6 （AtGFP：a-tubulin-6） were organized in parallel, straight and dense bundles, radiating from the ventral side to the dorsal side, and most of them were localized perpendicularly to the ventral wall; （iii） under the same environmental conditions, treated with SNP for 30 min, the radial arrays of microtubules in guard cells began to break down, twisted partially and be- came oblique or exhibited a random pattern; （iv） furthermore, the involvement of cytosolic Ca^2＋ in this event was tested. Stomatal aperture assays revealed that BAPTA-AM （a chelator of Ca^2＋） greatly suppressed the effect of NO on stomatal closure; however, it did not show the same function on stomatal closure induced by vinblastine. When BAPTA-AM was added to the SNP-pretreated solution, the SNP-induced disordered microtubulue cytoskeleton in guard cells underwent rearrangement in a time-dependent manner. After 30 min of treatment with BAPTA-AM, the cortical microtubules resumed the original radial distribution, almost the same as the control. All this indicates that NO may promote rearrangement of microtubule cytoskeleton via elevation of [Ca^2＋]cyt （free Ca^2＋ concentration in the cytoplasm）, finally leading to stomatsl closure.     

Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning, China: New 40Ar/39Ar dating of the Yixian and Tuchengzi

We report new ⁴⁰Ar/³⁹Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion ⁴⁰Ar/³⁹Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion ⁴⁰Ar/³⁹Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca/K ratios, excellent reproducibility and gave a mean age of 125.0 ± 0.18 (1SD) ± 0.04 (SE) Ma. Single sanidine crystal total fusion ⁴⁰Ar/³⁹Ar analyses of the Hengdaozi tuff gave a mean age of 125.0 ± 0.19 (1SD) ± 0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4 ± 0.19 (1SD) ± 0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.