五自由度立体视觉仿真平台设计与建模

从立体视觉与机器人控制集成的角度出发,建立了一个主动立体视觉跟踪和定位系统,用于柔性装配线中装配零件的运动跟踪和装配工位的精确定位。该系统具有五个自由度,其中三个是平移自由度,两个是转动自由度,该文针对平台的结构进行了运动学建模和分析,采用D—H方法建立了五自由度立体视觉平台的运动学模型,得到运动学的正解。在该运动学方程基础上开发了系统仿真平台,介绍了’系统仿真平台的设计原理和操作特点。该仿真平台验证了机构设计的正确性,验证了五自由度平台运动学分析的正确性。该仿真平台采用虚拟现实建模方法,建立了五自由度平台的三维立体模型和立体视觉跟踪运动物体的实验模型,具有良好的交互性和开放性。     

Vehicle Dynamics Modeling and Electronic Stability Program/ Active Front Steering Sliding Mode Integrated Control

Chassis integrated control can significantly improve vehicle handling stability and comfort. Because of the complexity of the problem, it has attracted significant research attention. We built a vehicle nonlinear dynamic model with multi‐degree freedom, including body movement, wheel movement, and electronically controlled hydraulic power steering system. We compared the magic formula tire model, Dugoff tire model, brush tire model, and LuGre dynamic friction tire model and steady model. The precision of the model was verified by a comparison between simulation results and the real vehicle test results. Then, based on the vehicle dynamics model, an AFS (active front steering) controller was designed based on sliding mode variable structure control, and an AFS and ESP (electronic stability program) integrated coordination controller was proposed. Finally, based on the nonlinear tire model and multi‐DOF (degree of freedom) vehicle model, sinusoidal and step steering angle input simulation analysis was proposed on different road friction coefficients. The results show that the vehicle has better response characteristics with coordinated control strategy when compared with AFS and ESP only control. The evidence suggests that the proposed integrated control system in this paper can improve vehicle stability and safety.     

Undulatory locomotion and effective propulsion for fish-inspired robot

Swimming, turning, and whip-sweeping propulsion for carangiform locomotion of a fish robot are investigated by means of a 4-link planar tail and an autonomous underwater vehicle (AUV)-like model. It is observed that excellent acceleration occurs when a whip sweeping behavior has been applied to the fish tail. The forward speed can even increases twice to the nominal swimming via the simulation study. The efficient movement is thus incorporated to the fish robot for agile movement. The robot's swimming patterns realize the effect in terms of the forward swimming, turning swimming, acceleration increasing, descended swimming, ascended swimming, depth regulating, and self-stabilization. Verification is accomplished by incorporating the 4-link planar tail, AUV-like model, and a two degree-of-freedom (DOF) barycenter mechanism. The four-link planar tail and 2-DOF barycenter mechanism act, respectively, as the thrust generator and stabilizing actuator for the fish robot. Sliding mode control (SMC) has been applied for three-dimensional (3D) trajectory tracking. Simulation results illustrate satisfactory performances of the fish robot in terms of the fish-like behaviors and maneuverability, which are due to the consequence of the mimicked predator-fish behaviors and performance robustness of the SMC for trajectory tracking under ocean current perturbations and modeling uncertainties.     

基于二维关节型人体模型和EM算法的人体跟踪

提出一种跟踪单眼图像序列中的行人,并恢复其运动参数的新方法.在跟踪中采用了基于SPM(Sealed Prismat Model)扩展的二维纸板人模型取代三维人体模型,以获取更快的计算速度.作者使用EM算法在概率框架下进行运动估计,同时,算法也考虑了混合的运动模型和运动约束,以减小解的搜索空间.试验结果证明了该方法的有效性.     

基于CPG控制的双髻鲨仿生机器人设计与实验研究

随着人类对自然的探索越来越深入,新型水下航行器的需求与日俱增,仿生机器人因其特殊的推进方式和高效的推进效率而受到越来越多的关注,而传统的仿生鱼类仅模拟了流线型外壳,少有提及仿生对象本身结构对于仿生性能的影响,本文提出了一种基于中央模式发生器(CPG)的类双髻鲨仿生机器人.以鱼类基本运动形态为基础,将鱼身抽象为关节连杆结构,建立了三关节四连杆的仿生机器鱼模型并进行了仿真计算.根据步态规律预估了其运动性能,随后通过实验验证了可行性.本仿生鱼旨在以简单的机械结构和较低的控制成本,实现对双髻鲨的最大限度模拟,得益于良好的仿生结构,中央模式发生器的引入,以及柔性硅胶材料在鱼身的应用,此机器人拥有体型小,控制简单,地形适应能力强,能量利用率高等特点,与传统水下推进器相比噪音更小,环境适应能力更强,在科研、农业等行业均具有广泛的应用前景,如野外勘测,水下救援,水域巡逻等.     

Catadioptric Visual Servoing From 3-D Straight Lines

In this paper, we consider the problem of controlling a 6 DOF holonomic robot and a nonholonomic mobile robot from the projection of 3-D straight lines in the image plane of central catadioptric systems. A generic central catadioptric interaction matrix for the projection of 3-D straight lines is derived using an unifying imaging model valid for an entire class of cameras. This result is exploited to design an image-based control law that allows us to control the 6 DOF of a robotic arm. Then, the projected lines are exploited to control a nonholonomic robot. We show that as when considering a robotic arm, the control objectives are mainly based on catadioptric image feature and that local asymptotic convergence is guaranteed. Simulation results and real experiments with a 6 DOF eye-to-hand system and a mobile robot illustrate the control strategy.     

Bio-harmonized control experiments of a carangiform robotic fish underwater vehicle

This paper presents experimental implementation and comparison of three different control schemes of a bio-inspired robotic fish underwater vehicle. The dynamics model is obtained by unifying conventional rigid body dynamics and bio-fluid dynamics of a carangiform fish swimming given by Lighthill’s(LH) slender body theory. It proposes an inclusive mathematical design for better control and energy efficient path travel for the robotic fish. The system is modeled as an two-link robot manipulator (caudal tail) with a mobile base (head). This forward thrust drives the robotic fish head represented by a combined non-linear equation of motion in earth fixed frame. We develop and compare the dynamic motion closed loop control strategy of the bio-harmonized robotic fish based on three different non-linear control schemes using CTM (Computed Torque Method), FF (Feed-Forward) controllers both with dynamic PD compensation and finally a proposed combination of CTM with FF. An inverse dynamic control method based on non-linear state function model including hydrodynamics is proposed to improve tracking performance. CTM control generates a feedback loop for linearization and decoupling robot dynamic model with a shorter response time, while a dynamic PD compensation in the FF path is employed by FF scheme through the desired trajectories. FF model-based strategy results in an improved tracking and shorter route to travel between two points. Overall results indicate that performances of the proposed control schemes based on the inverse dynamic model are comparable and useful for robotic fish motion tracking in fluid environment.     

A novel high degree of freedom sparse array with displaced multistage cascade subarrays

The coprime array is a recently developed sparse array that is widely used in direction-of-arrival (DOA) estimation. The degree of freedom (DOF) for existing coprime arrays relies on the virtual array model, which is limited to the array structure. Furthermore, the continuous virtual array aperture is restricted. This paper aims to propose a novel high DOF sparse array with displaced multistage cascade subarrays to further increase the length of the continuous virtual array and improve the DOF. Through cascading and separating the same sparse arrays, the continuous virtual array aperture is improved and the accuracy of the direction-of-arrival estimation is increased. It is proved that the range of the displaced distance for the maximized continuous virtual array can be obtained. The comparison between the array configuration presented in this paper and the existing common arrays are analyzed. The simulation experiments show that, compared with the uniform array, the coprime array, the nested array, and the coprime array with displaced subarrays (CADiS), the sparse array configuration proposed in this paper can significantly increase the aperture of the continuous virtual array, greatly improve the array DOF and the DOA estimation accuracy, and effectively estimate the DOA of multiple sources in underdetermined conditions.     

超空泡航行器极点配置变结构控制方法研究

超空泡航行器在航行过程中，尾部会周期性拍打空泡壁而表现出强烈的“尾拍”现象，尾部空泡是由空化器经历的历史位置形成，呈现强烈的时滞特性，动力学建模和稳定控制是制约其发展的核心难题。针对泡体耦合问题，建立了空泡/刚体相对几何关系一体化实时解算的动力学模型。针对后体非线性特性，采用分段线性化方法，在保留后体尾拍非线性特性的基础上，建立了面向控制的简化模型。为了解决超空泡航行器非线性时滞控制问题，针对弹体运动极其敏感、操纵效率高等特点，采用极点配置的方式将控制模型配置到理想状态。针对尾拍过程非线性和不确定极大的特点，建立了面向扰动的变结构控制器，实现超空泡航行器扰动运动控制。采用极点配置变结构控制方法，分别设计了滚转通道和俯仰通道控制律。利用泡体耦合动力学模型进行6DOF控制闭环轨迹仿真，稳定巡航过程中深度控制误差小于0.1m，滚转角控制误差小于4°，表明该控制方法能够对航行器滚转角和深度实现稳定控制，控制效果较好，能够满足超空泡航行器航行要求。     

胸鳍推进机器鱼俯仰稳定性分析

胸鳍推进机器鱼的胸鳍在通过扑动产生推力的同时,也会产生纵向扰动,引起机身的俯仰运动,对应用产生一系列的影响.本文在传统潜艇稳定性概念的基础上建立了胸鳍推进机器鱼的俯仰稳定性模型,证明了机器鱼的俯仰运动系统是一个二阶线性系统;分析了由胸鳍扑动引入的扰动,证明其中包含常量分量、扑动频率的一倍频分量和二倍频分量.最后进行了样机的游动实验,实验结果间接证明了俯仰运动模型和胸鳍扑动扰动模型的正确性.     

Internal model based robust inversion feedforward and feedback 2DOF control for LPV system with disturbance

To reduce the adverse effects on the control performance and disturbance rejection caused by system uncertainty, a novel internal model based robust inversion feedforward and feedback 2DOF control approach was proposed for LPV system with disturbance. The proposed control approach combines the internal model control and robust inversion based 2DOF control, it utilizes internal model based control to reject external disturbance, utilizes robust inversion 2DOF control to enhance the control resolution and guarantee the system control performance. At first, a LMI synthesis approach for LPV system model identification and a disturbance compensator optimization design method which could minimize H_∞ norm of output error caused by disturbance are presented. Then, combined with internal loop for disturbance compensation, a robust inversion feedforward controller is designed by robust inversion approach and the feedback controller which could render the requirements of reference signal tracking performance and robustness satisfied is obtained by the H_∞ mixed sensitivity synthesis approach. Finally, atomic force microscopy (AFM) vertical positioning simulation experiments are conducted and the experiment results showed that the proposed control approach could achieve better output performance and disturbance rejection compared with conventional internal model based control and robust inversion based 2DOF control approach.     

Maneuverability modeling and trajectory tracking for fish robot

This study develops a 6-DOF mathematical model for a robotic fish that considers surge, sway, heave, roll, pitch, and yaw. The model considers the conditions of a fish swimming in ocean current perturbations similar to the ocean current perturbations of the slender-body autonomous underwater vehicles. For swimming and turning behaviors, a nonlinear, dynamic, carangiform locomotion model is derived by using a planar four-link model. A 2-DOF barycenter mechanism is proposed to provide body stabilization and to serve as an actuating device for active control design. A barycenter control scheme is developed to change the center of gravity of the robot fish body by moving balancing masses along two axes. The projected torque on x and y axes propel pitch and roll angles to the desired settings. A Stabilizing controller, fish-tail mechanism, rigid body dynamics, and kinematics are incorporated to enable the fish robot to move in three dimensional space. Simulation results have demonstrated maneuverability and control system performance of the developed controller which is proposed to conduct path tracking of the robot fish as it swims under current perturbations.     

平面三自由度可控挖掘机构动力学建模与控制器设计

以一种平面三自由度可控挖掘机构为例,运用拉格朗日方法建立了机构的刚体动力学模型,求解得到了各主动杆的系统广义力;进而针对其半闭环控制系统的控制策略进行研究,基于机构驱动元件-交流控制电机及其驱动器的数学模型,运用模糊算法设计了一种模糊-PID双模控制器并对其进行仿真分析.结果表明:基于模糊算法的控制器在超调量、调节时间、上升时间和抗干扰能力等方面均具有较好性能,满足系统的控制要求.     

基于神经网络滑模的智能车辆横向控制

以智能车辆为研究对象,针对车辆模型存在高度非线性动态特性、参数不确定性以及行驶时受外部干扰较多导致控制精度不高、鲁棒性差等问题,提出了采用径向基函数(RBF)神经网络滑模控制方法.建立2自由度线性车辆模型和自由度非线性整车模型,在传统2自由度车辆控制模型状态方程的基础上推导出新的状态方程并以此设计了相应控制器.利用李雅普诺夫(Lyapunov)稳定性理论推导出神经网络的权,并证明控制系统的稳定性.仿真结果表明:与传统的滑模控制方法相比,该方法控制精度高,有较强的鲁棒性.     

Robust orientation control of multi‐DOF cell based on uncertainty and disturbance estimation

Multiple degrees‐of‐freedom (multi‐DOF) cell orientation control is a vital important technique involved in single cell surgery applications. Currently, few studies have been performed toward automation of multi‐DOF cell orientation control using robotically controlled optical tweezers. In this paper, a robust control framework is developed to perform multi‐DOF cell rotational control with consideration of model uncertainties and external disturbances. Both simulation and experimental studies are presented to illustrate the performance of the proposed control strategy. The main contributions of this work lie in that this is the first time to develop a unified framework to achieve multi‐DOF cell orientation control without the need for accurate dynamic model parameters and/or any knowledge about uncertainty characteristic, which greatly enhances the robustness of the overall system.     

直升机座舱操纵装置舒适性建模与仿真

建立了完整的5自由度人体上肢舒适操纵优化模型。建模时综合考虑了人体上肢生理结构及其运动特性,提出了基于RULA方法的人体上肢舒适操纵优化模型的建模方法。基于层次化、模块化的建模原则,整个仿真模型最终在SimMechanics平台上得到了实现。采用测定直升机飞行员人体数据,与CATIA仿真结果对比,验证了模型的合理性和有效性,得出了平面布局内直升机总距杆操纵舒适度分布曲线,结果可为直升机座舱操纵界面优化设计提供参考。     

基于模糊控制的汽车主动悬架仿真研究

本文建立了汽车振动的四分之一车体悬架模型和悬架系统的振动微分方程,并利用Matlab／Simulink软件实现了两自由度主动悬架的仿真模型。应用传递函数方法,对主动悬架在不同路况下的控制策略进行了深入研究,给出了相应的模糊控制策略,并进行仿真实验。仿真结果表明,装备了主动悬架的整车与被动悬架控制相比,前者在很大程度上降低了车身加速度、悬架动挠度和轮胎的相对动载荷,从而有效地提高了汽车的乘坐舒适性和操纵稳定性。     

Fuzzy Control of a Helio-Crane

In this paper we present a comparison of two fuzzy-control approaches that were developed for use on a non-linear single-input single-output (SISO) system. The first method is Fuzzy Model Reference Learning Control (FMRLC) with a modified adaptation mechanism that tunes the fuzzy inverse model. The basic idea of this method is based on shifting the output membership functions in the fuzzy controller and in the fuzzy inverse model. The second approach is a 2 degrees-of-freedom (2 DOF) control that is based on the Takagi-Sugeno fuzzy model. The T-S fuzzy model is obtained by identification of evolving fuzzy model and then used in the feed-forward and feedback parts of the controller. An error-model predictive-control approach is used for the design of the feedback loop. The controllers were compared on a non-linear second-order SISO system named the helio-crane. We compared the performance of the reference tracking in a simulation environment and on a real system. Both methods provided acceptable tracking performance during the simulation, but on the real system the 2 DOF FMPC gave better results than the FMRLC.     

基于CFD的仿鲹科机器鱼动力学建模与运动控制

仿生机器鱼的运动控制是仿生机器鱼推广应用的基础;然而,仿鲹科机器鱼的推进一般采用鱼体波数据,很少采用真实鱼类游动数据;为了深入探究仿鲹科机器鱼运动控制方法,采用了计算流体力学方法,通过标定流体介质、来流速度、鱼体几何形状等措施,利用Fluent软件进行了建模,然后针对鱼体波数据和真实金枪鱼游动采样数据两种不同推进数据对仿生机器鱼进行了仿真和实验;结果表明对于多关节仿生机器鱼推进方面,真实金枪鱼游动采样数据相较于常见的鱼体波产生的推进数据,在躯干进行大幅值摆动的情况下效果更好;这一仿真和实验对比为仿鲹科机器鱼的高效运动控制提供了一种新思路。     

直流位置伺服系统的二自由度分数阶控制

为提高直流位置伺服系统的控制性能,提出了一种2自由度（two degree-of-freedom,2DOF）分数阶控制方法．通过设计一种2DOF控制结构,实现了系统的跟随和抗扰特性的解耦控制;将内模控制（internal model control,IMC）与分数阶控制相结合,选用分数阶滤波器,推导出了跟随控制器和抗扰控制器设计方法;根据控制性能的要求,利用系统截止频率和最大灵敏度指标,实现了2DOF控制器参数的解析整定．仿真实验结果表明,2DOF分数阶控制方法具有良好的位置跟随特性和抗干扰能力．