Dynamic Modeling and Motion Simulation for A Winged Hybrid-Driven Underwater Glider

PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV （autonomous underwater vehicle）. It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.

Stability Analysis of Hybrid-Driven Underwater Glider

Hybrid-driven underwater glider is a new type of tmmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steady- state operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulations.and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

Modelling and Simulation of System Dynamics of Hybrid-Driven Precision Press

Different from conventional mechanical systems with single degree of freedom (DOF), the main idea of the system of hybrid-driven precision press is to combine the motion of a constant speed motor with a servomotor via a two-DOF mechanism to provide flexible output. In order to make the feasibility clear, this paper studies theoretically the dynamic characteristics of this hybrid-driven mechanical system.Firstly,the dynamics model of the whole electromechanical system is set up by combining dynamic equations of DC motors with those of two-DOF nine-bar mechanism deduced by the Lagrange′s formula. Secondly through the numerical solution with the fourth Runge-Kutta, computer simulation about the dynamics is done, which shows that the designed and optimized hybrid-driven precision press is feasible in theory. These provide theoretical basis for later experimental research.

A New Design Method for Realizing Accurate Track of Hybrid-driven Five-bar Mechanism

The concept of virtual slider crank mechanism is proposed and decoupled to obtain parameters of controllable five bar mechanism without any principle error for any given trajectory. The model is simple and easy to solve. This method has no convergence,flexible workspace and singularity of the mechanism problem. Through this method,we don’ t need any curve to fit the trajectory point. Using MATLAB program to calculate,the computation time can be reduced to less than 3% of the original. Finally,an example is given to illustrate the method which is meanwhile compared with the traditional five bar design method.

Research and experiment of a novel flower transplanting device using hybrid-driven mechanism

Aiming at decreasing the component complexity and cost of flower transplanting machine,an integrated transplanting method for picking and planting flower seedlings was proposed,and a hybrid-driven five-bar parallel mechanism was designed.A“beak-shaped”trajectory was designed for integrated transplanting requirements,and meantime,either the posture requirements of transplanting claw were determined.Based on the transplanting trajectory of the mechanism,a corresponding mathematical model for solving the link parameters was established,and then the five-bar mechanism was divided into two bar groups,optimization was conducted in two steps based on genetic algorithm and NSGA-II algorithm.Consequently,the optimal solution of the hybrid-driven five-bar parallel mechanism for flower seedling transplanting was obtained.Compared with similar designs,the trajectory displacement of the proposed mechanism is larger in the condition of smaller link size,which indicates that the mechanism can effectively decrease the machine size.The real-time controllable motor angular acceleration fluctuation is smaller and the commutation times are less,which has the advantage of reducing the difficulty of the mechanism control system.Subsequently,the correctness of the design method is verified by kinematics simulation.Finally,the synchronous linkage motion control methods of the two motors were designed,a transplanting experiment of the prototype was carried out,the picking success rate had reached 90%-93.4%and transplanting success rate was 80.5%-86.9%during experiment,which showed that the integrated operation of picking and planting flower seedlings can be realized by the proposed mechanism.

Design,hydrodynamic analysis,and testing of a bioinspired controllable wing mechanism with multi-locomotion modes for hybrid-driven underwater gliders

Hybrid-driven technology,which can improve the sailing performance of underwater gliders(UGs),has been successfully used in ocean observation.However,a hybrid-driven UG(HUG)with an added tail propeller is still unable to achieve backward and turning motion with a body length radius,and the hydrodynamic pitch moment acting on the HUG that is mainly caused by the fixed-wing makes it difficult to achieve high-precision attitude control during fixed-depth navigation.To solve this problem,a two-degree-of-freedom bioinspired controllable wing mechanism(CWM)is proposed to improve the maneuverability and cruising ability of HUGs.The CWM can realize five motion modes:modifying the dihedral angle or anhedral angle,changing the frontal area of the wing,switching the wing from horizontal to be a vertical rudder,flapping the wing as propulsion,and rotating the wing as a vector propeller.First,the design process of the CWM is provided,and hydrodynamic forces in each motion mode of three CWMs with different trailing edge sweepback angles(TESA)and attitude angles are analyzed through computational fluid dynamics simulation.The relationship between hydrodynamics and the attitude angles or TESA of the CWM is analyzed.Then,experiments are conducted to measure the hydrodynamics of the CWM when it is in a flapping wing mode and rotating the wing as a vector propeller,respectively.The hydrodynamic forces obtained from the simulation are consistent with data measured by a force sensor,proving the credibility of the simulated hydrodynamics.Subsequently,by applying the results of the hydrodynamic force in this study,the flapping trajectory of the wingtip is planned using the cubic spline interpolation method.Furthermore,two underwater demo vehicles with a pair of CWMs are developed,and experiments are conducted in a water tank,further validating and demonstrating the feasibility of the proposed CWM.

基于数据物理混合驱动的超短期风电功率预测模型

为提升超短期风电功率预测精度,提出一种数据-物理混合驱动的超短期风电功率预测方法。首先,构建一种融合双向门控循环单元的残差网络结构,将其在测试集的预测结果作为预测模板。然后,根据风速-风电转换特性,基于多项式-线性回归模型拟合风电场风速-功率曲线,在风速高波动时点,以物理机理透明的风速-功率曲线进行预测。最后,根据风速波动阈值建立不同模型之间的动态切换机制,按切换的时点修改模板预测值,对于修正风速小于切入风速的时点,将预测值置零。在吉林省某装机容量为400.5 MW的风电场提供的数据上进行仿真实验得到,测试集第16步预测的平均归一化均方根误差为0.1589,全部切换中有利切换占比达到90.86%,验证了提出的超短期风电功率预测模型的有效性和适用性。

数模联动的多特征工件加工能耗预测方法研究

在实际切削加工过程中材料去除率是不断变化的,现有将其视为恒量的能耗建模方法难以实现能耗准确预测。为了提高切削过程能耗预测精度,提出了一种基于材料去除率的数模联动加工能耗预测方法。首先,基于切削过程刀具与工件的接触关系分析了切入、完全切入和切出阶段材料去除率变化规律,并对相应的加工能耗特性进行了分析;其次,提出了数据驱动的刀具切入,切出阶段加工能耗预测方法,以及模型驱动的完全切入阶段加工能耗预测方法,实现加工过程能耗准确预测;最后,利用实验案例验证了所提模型及方法的有效性,为今后研究能耗预测精度奠定了基础。

机电系统网络控制课程的多维度混合式教学探索与实践

针对研究生课程机电系统网络控制的教学现状与发展需求,开展多维度混合式教学探索与实践。构建包含课堂讲授、资源库、专题研讨等在内的线上线下多维度教学体系;针对主题研讨实践环节引入翻转课堂,以项目驱动和研讨式教学引导学生分组完成课程相关的项目任务,掌握并运用所学知识分析解决问题,体验科学研究的过程与思维方法,形成理论知识到科研实践的闭环训练;最终建立形成性和终结性相结合的多元考核评价体系,旨在通过课程学习培养专业基础扎实、科研素养和工程实践能力突出的高端创新型人才。

高职“机械设计基础”课程混合式教学改革创新路径研究

基于“机械设计基础”这门课程的特点和高职学习者学情,探索“学做研创”专业基础课程改革路径,通过设计不同的产品结构设计主题,以机械产品设计为主线,有机融入“机械原理设计→机械结构设计→机械产品评价”教学方式,创新实施基于成果导向的“1+1+N”线上线下混合式教学模式,以宿舍为单位组建学习型组织,团队协作完成不同难易程度的机械作品以检验学习成果,实现“教与学、学与做、做与创”深度融合,让“学习者成为课堂主体”“教师成为课堂主导教练员”,打造高效优质金课堂。

基于混合驱动的分离罗拉运动轨迹规划研究

针对当前棉精梳机分离接合机构运动输出特性固定、振动大等问题,分析棉精梳机分离罗拉分离接合工艺,确定分离罗拉运动的位移关键点位置,根据差动轮系的运动规律提出交替驱动和分段驱动2种动力分配方案,并采用三次样条曲线作为交替驱动位移曲线、S型加减速曲线作为分段驱动位移曲线,通过对比分析得到最佳分离罗拉运动轨迹。指出:当设定棉纤维长度为30 mm时,2种驱动方案均能满足分离接合要求;采用混合驱动机构对分离罗拉高速正反转运动进行分解,实现伺服电机混合驱动分离罗拉,其运动性能更佳。

基于数据驱动的混合式教学质量保障机制的研究——以民办高职院校为例

本研究的目的是将基于数据驱动的混合式教学质量保障机制融合到高等院校的教学质量保证体系中,试图对所确定的问题进行更深入的理解,以便提出干预和变革,加强高等院校混合式教学和学习过程,最重要的是,改善高等院校的教学质量和学习体验。为了实现这一目标,本研究首先明确基于数据驱动的混合式教学质量保障机制的作用,进而论述基于数据驱动的混合式教学质量保障机制的设计,最终提出基于数据驱动的混合式教学质量保障机制的实现。所做研究与高等教育混合式教学质量增强维度有关,是协助高等院校教务部门加深对混合式教学质量管理及保障的探索,具有一定的参考和借鉴意义。

基于内嵌物理知识卷积神经网络的电力系统暂态稳定评估

针对现有数据驱动的电力系统暂态评估方法依赖大规模数据集且可解释性不足的问题,文中将物理知识嵌入传统数据驱动方法,提出一种基于内嵌物理知识卷积神经网络的电力系统暂态稳定评估方法。该方法考虑大规模风电并网的电力系统,将电力系统暂态稳定物理方程内嵌至神经网络损失函数,通过神经网络直接逼近物理过程,使输出结果满足物理规律,提高暂态稳定评估的可靠性与可解释性。通过数据与知识双驱动,所提方法不依赖大规模训练数据集,依然具有较好的鲁棒性与泛化能力。此外,所提方法通过卷积神经网络进行特征提取与降维,解决拓扑数据无法直接作为神经网络输入的难题。在含风机的IEEE 9节点和IEEE 39节点测试系统上的实验结果表明,所提方法在准确率、计算效率、泛化能力等方面相较现有方法有显著提升。

精梳机分离罗拉齿轮传动机构优化

混合驱动的精梳机分离罗拉齿轮传动机构的动力学性能直接影响车速的提高,为改善传动机构的动力学性能,首先,分析现有混合驱动的精梳机分离罗拉齿轮传动机构,采用集中质量法建立传动机构的固有频率模型,并计算传动机构在不同精梳机车速下的激励频率,发现当车速为600钳次/min时机构会出现共振;然后,采用导数法建立传动机构固有频率对机构中各个构件转动惯量的灵敏度模型,发现行星轮p的转动惯量对一阶固有频率的影响较大;最后,通过优化传动机构中WW型差动轮系的各个齿轮齿数以改变其转动惯量,使传动机构的一阶固有频率比原先提高了43.44%,避免了机构在600钳次/min时出现共振。

机理模型与集成学习混合驱动的机器人关节摩擦建模方法

机器人一体化关节广泛应用于医疗、协作机器人等领域,其摩擦特性是影响机器人性能的关键因素.为此,提出了一种机理模型与集成学习混合驱动的机器人关节摩擦建模方法,以提高模型精度.首先,综合考虑转速、负载等关节摩擦特性的影响因素及其周期波动特性,基于先验知识和物理分析分别建立了伺服电机与谐波减速器的参数化机理模型,描述摩擦特性的变化规律.然后,针对机理建模中因线性假设、忽略高阶项等产生的非线性残差,提出了基于eXtreme gradient boosting(XGBoost)的残差补偿模型建模方法,通过采用Boosting集成学习策略,提高残差补偿模型的泛化能力.同时,采用贝叶斯优化方法进行XGBoost模型的超参数寻优,以提高模型精度和训练效率.相比于传统的参数化机理模型,本文所提出的混合驱动模型具有更高精度.与反向传播神经网络、支持向量机、长短时记忆神经网络等多种典型方法的对比实验表明,本文所提出的基于XGBoost的残差补偿模型具有更强的特征提取能力,能够较好地预测强非线性的波动摩擦残差,有效地提高了整体模型的精度.

基于捕获点理论的混合驱动水下刀锋腿机器人稳定性判据

由8个推进器和6条刀锋腿混合驱动的水下机器人可在水底或水下结构物表面上行走.所提方法旨在研究这类机器人运动稳定性的评判准则,即稳定性判据.现有的稳定性判据多集中于同一机构(腿)驱动的陆地机器人,未涉及混合驱动的水下刀锋腿机器人.针对该问题,提出了基于捕获点理论的混合驱动水下刀锋腿机器人稳定性判据.首先,在建立混合驱动水下滚动倒立摆模型的基础上,利用机器人运动状态预测摆动腿和支撑腿切换瞬间机器人的动能;然后,根据推进器所能提供的推力范围,计算迫使机器人静止的捕获点变化范围,即获取捕获域;最后,根据捕获域与支撑域的空间关系,判断机器人是否稳定,并计算机器人的稳定裕度.水下实验结果表明,所提出的稳定性判据具有较好的充要性和普适性.

机理-数据混合驱动的气象敏感负荷需求响应潜力评估

为准确评估电网中气象敏感负荷需求响应潜力,提出了一种基于机理-数据驱动方法融合的气象敏感负荷需求响应潜力评估方法。该方法根据数据驱动的双分支神经网络模型估算电网层级的气象敏感负荷功率,基于热力学等值模型建立气象敏感负荷的机理聚合模型,并以聚合功率与估算功率误差最小为目标,采用控制变量法和粒子群优化算法优化确定机理聚合模型的等效参数(温控负荷设备数量、温度设定值等),同时综合考虑用户舒适度与意愿度等因素评估气象敏感负荷需求响应潜力。实例验证结果表明,该方法估算的气象敏感负荷功率与温度具有显著相关性,获得的机理聚合模型等效参数及需求响应潜力与实际情况相符且合理。

电力系统定碳排运行域:概念与方法

该文首次提出电力系统定碳排运行域(committed carbon emissions operation regions,CCEOR)的概念,刻画电力系统低碳安全运行空间(low-carbon operation space,LCOS),为新型电力系统低碳、安全运行提供科学、全面的决策依据,进一步丰富现有的低碳分析理论。针对高维非线性时空耦合变量下,定碳排运行域边界求解的关键技术瓶颈,基于数据与模型混合驱动思想建立域边界的高效求解方法。该方法结合特征工程,基于注意力机制与深度卷积的神经网络架构,以及数据与模型混合驱动的训练机制,有效保障CCEOR边界求解的高效性和准确性。最后,通过IEEE-118测试系统进行仿真分析,验证CCEOR能够有效评估系统的低碳运行态势,并确定低碳安全的调控方向。同时,验证所提域边界求解方法的高效性和高维适用性。通过可视化分析CCEOR随关键约束的变化特性,剖析LCOS的边界特征并发现其存在的空间饱和现象,进一步揭示电力系统运行的电碳耦合机理。

机理和数据混合驱动的城市排水管网建模方法研究

针对城市排水管网的高精度仿真,提出一种机理与数据混合驱动的城市排水管网水力建模方法。该方法利用一维圣维南方程组和人工神经网络分别刻画排水系统中的水量传输过程、机理方程模拟的误差。为评估模型性能,以某市排水系统某排水片区为模拟对象建模,分别利用实际监测和数学试验进行混合驱动模型测试,并与纯机理驱动模型进行对比。结果表明混合驱动模型在实际降雨下流量、液位模拟准确性比纯机理模型提升26.5%;在数学试验场景下流量、液位准确性分别提升59.0%和6.1%,稳定性提升54.5%,2.6%;而模拟耗时仅增加了1.1%。研究提出的混合驱动仿真模型在一定程度上提升了模拟的准确性和稳定性,可更好地支撑城市排水系统的运行管理。

基于复数神经网络的双视角视觉转角测量方法

为改善单视觉的转角测量方法容易受到环境或系统随机干扰的不稳定性,提出了一种基于复数神经网络的双视角视觉转角测量方法。人为进行特征提取,并评估其与角度的相关性和单调性来进行特征筛选。为解决0°和360°标签数值差距大对训练结果的影响,将角度用欧拉公式表示,并构建复数输入,复数输出的复数神经网络来进行转角计算。实验结果显示,这种测量方法在测量准度上有显著提升,相比基于深度神经网络的单视角方法,其平均误差降低0.322°,均方根误差降低0.64°,在不同环境测试集上保持高效性能。该模型在保持传统数学模型的约束和稳定性的前提下,充分利用了双视角对于环境干扰的鲁棒性,结合复数神经网络对于角度标签的强大拟合能力,提高了径向视觉角度测量的准确性和稳定性。