Research trends in methods for controlling macro-micro motion platforms

With ongoing economic,scientific,and technological developments,the electronic devices used in daily lives are developing toward precision and miniaturization,and so the demand for high-precision manufacturing machinery is expanding.The most important piece of equipment in modern high-precision manufacturing is the macro-micro motion platform(M3P),which offers high speed,precision,and efficiency and has macro-micro motion coupling characteristics due to its mechanical design and composition of its driving components.Therefore,the design of the control system is crucial for the overall precision of the platform;conventional proportional–integral–derivative control cannot meet the system requirements,and so M3Ps are the subject of a growing range of modern control strategies.This paper begins by describing the development history of M3Ps,followed by their platform structure and motion control system components,and then in-depth assessments of the macro,micro,and macro-micro control systems.In addition to examining the advantages and disadvantages of current macro-micro motion control,recent technological breakthroughs are noted.Finally,based on existing problems,future directions for M3P control systems are given,and the present conclusions offer guidelines for future work on M3Ps.

基于Motion/AMESim的某风洞迎角机构建模与仿真研究

通过研究仿真软件Motion和AMESim的接口技术,搭建机械、液压和控制系统有机集成的联合仿真平台。以某风洞迎角机构为例,进行机、电、液一体化建模与仿真研究。仿真结果表明:Motion/AMESim联合仿真平台能对机、电、液系统的设计和分析提供理论支持,有广阔的应用和发展前景。

基于VL Motion和AMESim的液压六自由度平台联合仿真及试验研究

为研究六自由度平台的优化设计及控制策略,需要对系统进行详细建模。针对液压六自由度平台仿真建模方法进行研究,提出一种机电液联合仿真的建模方法。采用AMESim对液压系统和控制系统建模,Virtual.Lab对平台机构动力学部分建模,通过软件之间的接口将机械、液压控制系统两部分模型联合,建立液压并联机构的通用仿真模型。通过与试验结果的对比验证了仿真模型的正确性。与传统数学建模方式相比,该方法发挥了各软件的优势,使建模过程简捷且高效,适用于复杂装备的设计与研究。

基于耦合的Vitual Lab Motion & AMESim的下肢外骨骼机电液系统建模及仿真分析

利用Virtual Lab Motion对下肢外骨骼进行了结构建模。依据现有的临床步态分析数据——关节角度随时间的变化关系,通过运动学分析逆向得出所设计系统各个液压缸的理想控制曲线,即液压缸位移随时间的变化关系。依据仿真得到的力臂及液压缸速度可对电液系统的压力和流量进行估算,利用Virtual Lab Motion与AMESim的耦合仿真验证了系统的合理性。

基于Motion/AMESim的某变载机构的建模与仿真分析

某变载机构在运动过程中承受顺载和逆载工况且负载变化范围大,针对这一问题,该文利用LMS Virtual.Lab Motion和AMESim进行联合仿真,首先利用LMS Virtual.Lab Motion建立变载机构的三维动力学模型,然后在AMESim中建立液压控制系统模型,最后再对系统进行联合仿真。设计控制方案,通过仿真分析,优化系统参数,为变载机构的运动试验奠定理论基础。

Adaptive Sliding Control of Six-DOF Flight Simulator Motion Platform

There is proposed an adaptive sliding controller in task space on the base of the linear Newton-Euler dynamic equation of motion platform in a six-DOF flight simulator. The uncertain parameters are divided into two groups： the constant and the time-varying. The controller identifies constant uncertain parameters using nonlinear adaptive controller associated with elimination of the influences of time-varying uncertain parameters and compensation of the external disturbance using sliding control. The results of numerical simulation attest to the capability of this control scheme not only to, with deadly accuracy, identify parameters of motion platform such as load, inertia moments and mass center, but also effectively improve the robustness of the system.

Effects of Second-Order Sum-and Difference-Frequency Wave Forces on the Motion Response of a Tension-Leg Platform Considering the Set-down Motion

This paper presents a study on the motion response of a tension-leg platform(TLP) under first-and second-order wave forces, including the mean-drift force, difference and sum-frequency forces. The second-order wave force is calculated using the full-field quadratic transfer function(QTF). The coupled effect of the horizontal motions, such as surge, sway and yaw motions, and the set-down motion are taken into consideration by the nonlinear restoring matrix. The time-domain analysis with 50-yr random sea state is performed. A comparison of the results of different case studies is made to assess the influence of second-order wave force on the motions of the platform. The analysis shows that the second-order wave force has a major impact on motions of the TLP. The second-order difference-frequency wave force has an obvious influence on the low-frequency motions of surge and sway, and also will induce a large set-down motion which is an important part of heave motion. Besides, the second-order sum-frequency force will induce a set of high-frequency motions of roll and pitch. However, little influence of second-order wave force is found on the yaw motion.

Modelling of the Vortex-Induced Motion of A Single-Column Platform with Non-Linear Mooring Stiffness Using the Coupled Wake Oscillators

A phenomenological model for predicting the vortex-induced motion (VIM) of a single-column platform with non- linear stiffness has been proposed. The VIM model is based on the couple of the Duffing-van der Pol oscillators and the motion equations with non-linear terms. The model with liner stiffness is presented for comparison and their results are compared with the experiments in order to calibrate the model. The computed results show that the predicted VIM amplitudes and periods of oscillation are in qualitative agreements with the experimental data. Compared with the results with linear stiffness, it is found that the application of non-linear stiffness causes the significant reductions in the in-line and transverse motion amplitudes. Under the non-linear stiffness constraint, the lock-in behavior is still identified at 8<Ur<15, and the trajectories of the VIM on the xy plane with eight-figure patterns are maintained. The results with different non-linear geometrically parameters show that both in-line and transverse non-linear characteristics can significantly affect the predict in-line and transverse motion amplitudes. Furthermore, the computed results for different aspect ratios indicate that the in-line and transverse motion amplitudes increase with the growth of aspect ratio, and the range of lock-in region is enlarged for the large aspect ratio.

Nonlinear Random Motion Analysis of A Tension Leg Platform Consider- ing the Set-down Motion of A Floating Body

The dynamic analysis of a Tension Leg Platform （TLP） in random wave is investigated by considering the set-down of a floating body. The nonlinear restoring stiffness is derived with the set-down motion of a floating body and the coupled motion of the tension leg and platform and the differential equations of the motion are established. The study focuses on the influence of the set-down motion on the nonlinear response of the platform. By considering different significant wave heights and currents, motion responses of the platform are calculated and compared. The analysis shows that the set-down motion significantly increases the heave motion with low frequency and the equilibrium position of the heave motion with the set-down motion is much lower than that without set-down motion. The results in this paper indicate that the set-down motion has a major impact on the safety of the platform inproduction operation, and it is also a threat to the strength of tension legs and risers.

The Nonlinear Bifurcation and Chaos of Coupled Heave and Pitch Motions of a Truss Spar Platform

This paper presents the results from a numerical study on the nonlinear dynamic behaviors including bifurcation and chaos of a truss spar platform. In view of the mutual influences between the heave and the pitch modes, the coupled heave and pitch motion equations of the spar platform hull were established in the regular waves. In order to analyze the nonlinear motions of the platform, three-dimensional maximum Lyapunov exponent graphs and the bifurcation graphs were constructed, the Poincare maps and the power spectrums of the platform response were calculated. It was found that the platform motions are sensitive to wave fre- quency. With changing wave frequency, the platform undergoes complicated nonlinear motions, including 1/2 sub-harmonic motion, quasi-periodic motion and chaotic motion. When the wave frequency approaches the natural frequency of the heave mode of the platform, the platform moves with quasi-periodic motion and chaotic motional temately. For a certain range of wave frequencies, the platform moves with totally chaotic motion. The range of wave frequencies which leads to chaotic motion of the platform increases with increasing wave height. The three-dimensional maximum Lyapunov exponent graphs and the bifurcation graphs reveal the nonlinear motions of the spar platform under different wave conditions.

Platform motion minimization using model predictive control of a floating offshore wind turbine

Wind turbines are installed offshore with the assistance of a floating platform to help meet the world’s increasing energy needs.However,the incident wind and extra incident wave disturbances have an impact on the performance and operation of the floating offshore wind turbine(FOWT)in comparison to bottom-fixed wind turbines.In this paper,model predictive control(MPC)is utilized to overcome the limitation caused by platform motion.Due to the ease of control synthesis,the MPC is developed using a simplified model instead of high fidelity simulation model.The performance of the controller is verified in the presence of realistic wind and wave disturbances.The study demonstrates the effectiveness of MPC in reducing platform motions and rotor/generator speed regulation of FOWTs.

基于VL motion与AMESim的飞机起落架及舱门收放控制联合仿真

该文以某型飞机起落架及舱门收放系统为研究对象,采用VL motion与AMESim软件分别对起落架运动机构和液压控制系统建立模型并进行联合仿真,利用联合仿真模型求解得到起落架及舱门收放时间和流量需求并验证其符合性。结果表明:通过基于VL motion与AMESim的联合仿真可完成起落架在预定时间内的收放功能,可为飞机起落架收放系统设计及部件参数优化提供参考。

Kinect-Based Motion Recognition Tracking Robotic Arm Platform

The development of artificial intelligence technology has promoted the rapid improvement of human-computer interaction. This system uses the Kinect visual image sensor to identify human bone data and complete the recognition of the operator’s movements. Through the filtering process of real-time data by the host computer platform with computer software as the core, the algorithm is programmed to realize the conversion from data to control signals. The system transmits the signal to the lower computer platform with Arduino as the core through the transmission mode of the serial communication, thereby completing the control of the steering gear. In order to verify the feasibility of the theory, the team built a 4-DOF robotic arm control system and completed software development. It can display other functions such as the current bone angle and motion status in real time on the computer operation interface. The experimental data shows that the Kinect-based motion recognition method can effectively complete the tracking of the expected motion and complete the grasping and transfer of the specified objects, which has extremely high operability.

6-DOF Motion Assessment of A Hydrodynamic Numerical Simulation of A Semisubmersible Platform Using Prototype Monitoring Data

Hydrodynamic numerical simulations are used to conduct structural analyses and inform the design of engineered marine structures.In this paper,a hydrodynamic numerical model of“Nanhai Tiaozhan”(NHTZ)FPS platform was established according to its design specifications.The model was assessed with two sets of field monitoring data representing harsh and conventional sea states.The motion responses of the platform according to the measured data and the hydrodynamic simulation were compared by reviewing their statistical characteristics,distributions,and spectrum characteristics.The comparison showed that the hydrodynamic model could correctly simulate the frequency domain characteristics of the motion responses of the platform.However,the simulation underestimated the reciprocating motions of the floating body and the influence of slow drift on the motion of the platform.Meanwhile,analysis of the monitoring data revealed that the translational degrees of freedom(DOF)and rotational DOF of the platform were coupled,but these coupled motion states were not apparent in the hydrodynamic simulation.

Numerical Simulation of Motion Response of an Offshore Observation Platform in Waves

Offshore observation platforms are required to have great ability to resist waves when they are operating at sea. Investigation on the motion characteristics of the platforms in the sea can provide significant reference values during the platform design procedure. In this paper, a series of numerical simulation on the interaction of a triple-hulled offshore observation platform with different incident waves is carried out. All of the simulations are implemented utilizing our own solver naoe-FOAM-SJTU, which is based and developed on the open source tools of OpenFOAM. Duration curves of motion characteristics and loads acting on the platform are obtained, and a comparison between the results of the amplitude in different incident waves is presented. The results show that the solver is competent in the simulation of motion response of platforms in waves.

Investigation of Pitch Motion Portion in Vertical Response at Sides of a Tension-Leg Platform

Tendons vertically moor Tension-Leg Platforms （TLPs）, thus, a deep understanding of physical tendon stresses requires the determination of the total axial deformation of the tendons, which is a combination of the heave, pitch, and surging responses. The vertical motion of the lateral sides of the TLP is coupled with surge and constitutes a portion of the pitch motion. Tendons are connected to the sides of the TLP; hence, the total displacement of the lateral sides is related to the total deformation of the tendons and the total axial stress. Therefore, investigating the total vertical response at the sides of the TLP is essential. The coupling between various degrees of freedom is not considered in the Response Amplitude Operator （RAO）. Therefore, in frequency domain analysis, the estimated vertical RAO is incomplete. Also, in the time domain, only the heave motion at the center of TLP is typically studied; this problem needs to be addressed. In this paper, we investigate the portion of the pitch motion in the vertical response at the sides of the TLP in both the frequency and time domains. Numerical results demonstrate a significant effect of the pitch motion in the vertical motion of the edges of the TLP in some period ranges.

用于航空相机像移补偿的三轴稳定平台设计与研究

航空相机在工作过程中,由于载机的抖动干扰,拍摄过程中会产生像移,而像移是影响图像质量的主要原因。为航空相机配备一套稳定平台系统是解决像移问题有效的解决办法,稳定平台系统的原理是通过将航空相机成像传感器与干扰隔离来稳定视轴。为了稳定视轴,实现推扫拍摄,这里设计了一种三轴稳定平台,对三轴稳定平台的姿态补偿方式和结构设计进行了研究。通过分析像移对像质的影响,确定了轴系的旋转精度,推导了基于角速度的横滚轴、俯仰轴与航向轴框架交叉耦合的平台补偿方程。然后,根据轴系精度和运动补偿方程,设计并分析了三轴稳定平台结构,通过实验来验证视轴稳定的性能。实验结果表明,平台在载波干扰下具有良好的稳定性能。

漂浮式海上风力机自适应超螺旋滑模桨距控制

针对额定风速以上漂浮式海上风力机系统的输出功率稳定、浮式平台运动和疲劳载荷抑制任务目标,考虑系统非线性和模型参数摄动及风浪扰动,提出一种基于自适应超螺旋二阶滑模和干扰观测补偿的桨距角鲁棒控制方案。首先,实现漂浮式海上风力机的仿射非线性不确定系统建模;其次,构建考虑风力机额定转速和平台纵摇的滑模函数,设计控制增益自适应调节的超螺旋二阶滑模控制律;再次,采用干扰观测器补偿模型参数摄动和风浪扰动不确定项;最后,基于FAST与Matlab/Simulink在不同风浪环境下进行仿真,验证所提方案有效性和优越性。时域和频域仿真结果表明,与传统比例积分控制方案相比,所提方案对稳定风力机系统输出功率、抑制浮式平台运动及减少塔基载荷具有更好的控制效果。

基于无模型自适应控制的半潜式平台运动性能研究

南海海域油气资源极其丰富,半潜式平台在该海域工作时常常面临着系泊失效这一重大危险情况。该研究以一艘装配有悬链式系泊系统和DP-3动力定位系统的半潜式平台为研究对象,利用AQWA软件开展系泊失效前后半潜式平台运动性能研究。同时,借助于AQWA软件二次开发功能,将无模型自适应控制作为动力定位系统控制理论,以研究半潜式平台系泊失效后运动性能恢复。数值仿真模拟结果表明,采用无模型自适应控制作为动力定位系统控制理论的半潜式平台能很好地恢复系泊失效后的运动性能,有效地减小系泊失效带来的危害;基于偏格式动态线性化和全格式动态线性化的无模型自适应控制比基于紧格式动态线性化的无模型自适应控制能让半潜式平台更快地恢复运动性能。

基于三维运动捕捉技术构建蒙医震脑术三维虚拟仿真平台的视觉呈现

背景:基于三维运动捕捉技术可以构建精准的、客观量化的医学虚拟仿真模型,有利于临床学习者精准、深入理解和掌握各种传统疗术。目前中医虚拟仿真模型已有报道,但蒙医传统疗术的虚拟仿真模型尚未见报道。目的:构建一种基于三维运动捕捉技术的交互式三维可视化的蒙医震脑术虚拟仿真模型。方法:使用Motion Analysis三维光学运动捕捉系统和足底测力台采集蒙医专家的运动捕捉数据,在Motion Builder软件中构建震脑术三维动作模型,使用Maya软件构建角色模型并与动作模型相匹配,运动Unity3D软件构建蒙医震脑术虚拟仿真系统,系统整合蒙医震脑术操作3D动画、运动学和动力学参数信息。结果与结论:通过三维运动捕捉技术和计算机仿真重现蒙医震脑术操作,能够显示施术者和受试者的运动姿态,记录关节运动的关键空间位置参数与变化情况,得出运动过程中的运动学、动力学参数。运用交互式三维虚拟仿真技术,实现蒙医震脑术的三维虚拟仿真的视觉呈现,为蒙医震脑术手法的标准化、数字化、可视化研究奠定基础。