基于时变滑模结构的桥吊防遥定位控制器设计

针对变绳长条件下欠驱动桥式吊车系统的防摇和定位控制问题,提出了一种基于时变滑模的桥吊控制方法;该方法采用多滑模结构控制,在桥吊绳长变化的情况下,较好地实现了对桥吊小车位置和负载摆角的控制;该方法利用时变滑模面,减少了滑模面到达阶段的时间,提高了控制器鲁棒性;同时控制器设计中还采用了一种新的方法来削弱滑模控制器的抖振现象;利用李雅普诺夫理论证明了该控制方法的全局稳定性和收敛性,仿真结果验证了该方法的有效性。     

桥吊摆绳摆角的视觉检测

桥吊摆角的准确测量是实现吊车防摇控制的前提条件;文中将视觉识别技术引入到吊车防摆控制中来,提出了基于局部梯度变化和标准差的图像自适应增强处理算法,解决了不同背光条件下吊绳摆动位置信息获取问题,有效地实现了桥吊负载摆绳图像特征的提取;同时,采用两次下采样和梯度法相结合的圆心的识别算法,解决了圆检测的实时性问题,从而成功识别出目标及其所在的空间位置,并用几何方法准确地测量出负载钢丝绳的摆角;最后,实验结果证实了该方法的有效性。     

基于免疫遗传算法优化的集装箱桥吊防摇控制

桥吊系统存在严重的非线性,如果采用常规的PID控制器很难对其有较好的控制效果.可以采用基于遗传算法优化模糊控制器的方法对其控制,但采用普通遗传算法优化模糊控制器具有收敛慢的缺点,因此,本文提出了基于免疫遗传算法优化模糊控制的方法.仿真结果表明该控制器对桥吊防摇有很好的控制效果.且这种控制方法对于参数未知,时变负载扰动大的系统具有很好的工程实践价值.     

一种基于变频调速器的分布式群吊控制系统同步方法

针对铁路长轨搬运中多吊车协同工作过程中的晃动问题,给出一种基于变频器控制的分布式系统的同步方法.通过变频器自动调整吊车速度,进行运动偏差补偿,从而实现了群吊控制系统的同步控制.该方法还可实现吊车的软加速和软减速.     

双吊具欠驱动桥吊的建模与仿真

较之于传统的单吊具桥吊,双起升双吊具桥吊是一种新型高效集装箱装卸机械,但其本质上是一类复杂的欠驱动非线性系统,其建模和控制方法存在较大难度。利用拉格朗日分析方法和仿真手段对双起升双吊具桥吊的动力学特性进行了研究,分析了吊绳长度和负载变化对桥吊动态特性的影响,以及作业环境中的摩擦力和空气阻力对模型特性的影响;建立了双起升双吊具桥吊的动力学模型,并进行了简化。最后,仿真研究为验证双起升双吊具桥吊的动力学模型的正确性提供了依据。     

欠驱动三维桥式吊车系统自适应跟踪控制器设计

针对三维桥式吊车系统的欠驱动特性, 设计了一种目标轨迹自适应跟踪控制器. 相比其他常规的三维桥式吊车控制器, 它不需要对吊车模型进行任何近似解耦或线性化处理, 并且考虑了系统所受的摩擦力与空气阻力等干扰. 在负载质量和吊绳绳长等发生变化或存在不确定因素的情况下, 它依然能实现对台车的精确定位与负载摆动的有效抑制. 对于闭环系统的稳定性, 文中通过Lyapunov方法和芭芭拉定理对其进行了理论分析, 随后的实验结果也表明了这种自适应跟踪控制器良好的控制性能和对不确定性因素的适应性.     

采用单目视觉的桥吊负载空间定位方法

针对基于模板匹配算法的单目视觉桥吊负载空间定位系统中标识模板旋转、倾斜等造成的匹配性能降低的问题,提出一种结合垂直梯度方向线圆检测与线性预插值的桥式吊车负载实时空间定位方法。该方法通过设置一个附于负载上方的球形标识物, 利用球形标识物在被检测时对旋转和倾斜等情况不敏感的特性, 首先利用垂直梯度方向线的圆检测算法, 对兴趣区域内的球形标识物图像进行精确快速的检测; 再结合空间几何方法对球形标识物球心空间坐标进行计算; 此外, 还使用线性预插值的方法解决了空间坐标的实时反馈问题。通过物理实验, 将空间位置数据转换为负载摆角与吊绳绳长,与传统接触式方法进行对比。实验结果表明,该方法转换得到的摆角数据精确更高,且满足实时性要求;同时,绳长转换数据与接触式方法测得数据误差满足在2.49%以内,满足精度要求。     

桥吊时变滑模控制过程的优化建模仿真研究

利用传统方法对桥吊时变滑模控制策略中会产生收敛速度慢,控制作用不连续,误差大等诸多缺憾.针对这一问题,提出基于螺旋算法的桥吊时变滑模控制模型,在二阶超螺旋算法的基础上引入了新的高阶滑模控制律,跟踪了误差的高阶导数,建立滑动量,保证了控制的精度.仿真结果证明利用改进后的模型对桥吊时变滑模控制,具有控制过程收敛速度快、控制作用平滑连续等优势.     

基于实时内核的双起升双吊具桥吊实时仿真平台

双起升双吊具桥吊是一种复杂的多电机传动机械,其多电机协调控制需要实现桥吊操作的准确性、安全性和快速性;文中针对一种双起升双吊具桥吊实验装置的多电机协调控制的需要,构建了一个桥吊多电机实时仿真控制平台,提出了一种基于Real-TimeWorkshop(RTW)的实时内核的混合仿真实验构架,采用了S函数设计开发运动控制器驱动模块,并通过调用设备驱动函数操作运动控制器,最终实现桥吊多电机协调控制的方法;该方案具有技术先进、结构简单、使用灵活、成本低廉的特点,能够方便地实现针对双起升双吊具桥吊控制方法的数字仿真和半实物仿真。     

带有完整约束的双吊车系统输入整形控制

作为一种重要的物料运输工具,桥式吊车在各类工业场景中发挥着举足轻重的作用.然而随着负载体积/质量的增大,很多时候不得不使用两台吊车来协同运送负载.目前对于这类双吊车系统的防摆研究仍然较少.本文针对这一情况,率先提出了一种输入整形控制方法.具体来说,首先分析了双吊车系统中存在的完整约束,通过对系统模型的合理简化,在不失准确性的情况下获得了台车位移与负载姿态角之间的近似动力学关系.在此基础上,求取出系统真实的振荡周期并设计出了合适的输入整形器.该整形器能够在不影响台车定位的情况下,充分抑制负载的摆动,并且对系统参数不确定性具有良好的鲁棒性.仿真和实验结果也证明了这一点.     

基于滑模方法的桥式吊车系统的抗摆控制

针对桥式吊车这类欠驱动系统，提出一种基于滑模控制的抗摆方法．该方法将系统状态分成两组。构造出一种双层滑动平面．结合桥式吊车系统数学模型的特点。求取了总的滑模控制量并进一步设计了控制器的参数．采用Lyapunov方法，从理论上证明了各级滑动平面的稳定性．仿真结果验证了该方法对于桥武吊车系统抗摆控制的有效性．     

A novel trajectory planning-based adaptive control method for 3-D overhead cranes

A three-dimensional (3-D) overhead crane is a complicated nonlinear underactuated mechanical system, for which high-speed positioning and anti-sway control are the kernel objective. Existing trajectory-based methods for 3-D overhead cranes focus on combining efficient and smooth trajectories with anti-sway tracking controllers without regard for payload motion; moreover, the exact value of plant parameters is required for accurate compensation during the control process. Motivated by these facts, we present a two-step design tracking strategy which consists of a trajectory planning stage and an adaptive tracking control design stage for 3-D overhead cranes. As shown by Lyapunov techniques and Barbalat's Lemma, the proposed controller guarantees asymptotic swing elimination and trolley positioning result in the presence of system uncertainties including unknown parameters and external disturbances. Simulation results also showed the applicability of the proposed method with good robustness against parameter uncertainties and external disturbances.     

基于滑模控制的集装箱起重机防摇控制

针对集装箱起重机这类欠驱动系统,基于智能控制的方法,提出一种基于滑模控制的防摇方法。该方法先通过对集装箱起重机的数学模型进行线性化运算,然后设计2种滑模控制器,对线性简化的模型进行滑模控制,通过李雅普诺夫方法来证明所进行的滑模控制的有效性。通过Matlab的Simulink来搭建仿真模型,仿真模型的图形结果验证了该方法对于集装箱起重机系统防摇控制方面的有效性。     

Improved energy dissipation control of overhead cranes

In this paper, an improved energy dissipation controller is presented for overhead cranes. Our main contribution is the characterization of overhead cranes for which energy shaping method yields a significant storage function, where a nonlinear coupling controller is delivered that drastically increases the damping of the control system. Additional terms are fabricated to assure a soft start and a limited overshoot. In the frame of the Lyapunov theory, we apply LaSalle's invariance principle to illustrate the corresponding stability. Such a controller is experimented and some results are reported.     

A unified symplectic pseudospectral method for motion planning and tracking control of 3D underactuated overhead cranes

In this paper, a unified symplectic pseudospectral method for motion planning and tracking control of 3D underactuated overhead cranes is proposed. A feasible reference trajectory taking constraints into consideration is first generated offline by the symplectic pseudospectral optimal control method. Then, a trajectory tracking model predictive controller also based on the symplectic pseudospectral method is developed to track the reference trajectory. At each sampling instant, the trajectory tracking controller works by solving an open‐loop optimal control problem where linearized system dynamics is used instead to improve the computational efficiency. Since the symplectic pseudospectral optimal control method is the core algorithm for both offline trajectory planning and online trajectory tracking, constraints on state variables and control inputs can be easily imposed and hence theoretically guaranteed in solutions. By selecting proper weighted matrices on tracking error and control, the developed controller could achieve control objectives in both accurate trolley positioning and fast suppressing of residual swing angles. Simulations for 3D overhead crane systems in the presence of perturbations in initial conditions, an abrupt variation of system parameter, and various external disturbances demonstrate that the developed controller is robust and of excellent control performance.     

Skeletal-level control-based forward dynamic analysis of acquired healthy and assisted gait motion

In this paper, the system dynamics of an overhead crane are inverted by servo-constraints. The inversion provides a feedforward control for trajectory tracking of the system output. The overhead crane is inherently underactuated and modeled as a two-dimensional mechanical system with nonlinear system dynamics. Actuators are modeled as first-order systems to simplify implementation and account for velocity-controlled drives. The control based on servo-constraints is shown to be an effective method of trajectory control for overhead cranes. It will be demonstrated that the formulation is solvable in real-time using linear implicit Euler integration. The feedforward solution is made robust by an augmentation with LQR as well as a sliding mode controller. Experiments are conducted on a laboratory crane of 13 m motion range.     

Motion planning for three-dimensional overhead cranes with high-speed load hoisting

This paper proposes a systematic anti-swing motion-planning method for three-dimensional overhead cranes, based on the load-swing dynamics of a two-dimensional overhead crane. First, a model-following anti-swing control law is designed based on the load-swing dynamics of a two-dimensional overhead crane, where the Lyapunov stability theorem is used as a mathematical tool. Then a new anti-swing motion-planning scheme is designed for a two-dimensional overhead crane based on the model-following anti-swing control law and typical crane operation in practice. Finally, the new anti-swing motion-planning scheme is extended for a three-dimensional overhead crane, based on the geometric relationship between a three-dimensional overhead crane and its two-dimensional counterpart. As a result, the proposed method avoids solving the load-swing dynamics of a three-dimensional overhead crane which is much more complicated than that of its two-dimensional counterpart. Furthermore, the proposed method can be applied to any existing overhead cranes without increasing their actuator torque capacity. The effectiveness of the proposed method is demonstrated by generating high-performance anti-swing trajectories with high-speed long-distance load hoisting.     

Adaptive neural network hierarchical sliding mode control for six degrees of freedom overhead crane

This paper presents an effective control method for three-dimensional (3D) overhead cranes with six degrees of freedom (DOF). Two payload swings and an axial payload oscillation should be minimized besides driving the bridge, trolley, and hoisting drum to bring the payload to the desired position in space. First, a novel 3D-6DOF crane model is developed, where the sixth degree of freedom is axial cargo oscillation that has never been considered in previous studies. A controller is then designed using the hierarchical sliding mode control method. Moreover, a radial basis function neural network (RBFNN) is used to approximate the system's unknown dynamic model accurately. According to the Lyapunov principle, a control law and an updated law for the neural network's weight matrices are designed to ensure the stability of the closed-loop system. Simulation results on Matlab software show the proposed approach's effectiveness, such as smaller swing, minor axial oscillation, and precise position as desired.     

基于观测器的双吊具桥吊时变滑模同步控制

为针对双起升桥式吊车双吊具同步运行过程中普遍存在的无法精确建模、系统参数变化、外部扰动未知等问题,采用交叉耦合策略,提出了一种基于非线性扰动观测器的时变滑模同步控制方法。首先,采用时变滑模控制保证了控制器的全局鲁棒性;其次,利用非线性扰动观测器观测聚合扰动,对控制器进行扰动补偿;此外,提出一种可动态适应控制系统变化的变增益趋近律,有效抑制了控制输入抖振、缩短了趋近时间。最后,利用Lyapunov理论证明控制器的渐进稳定性,并通过仿真结果表明了所提出方法的有效性,控制器在未知扰动存在的情况下仍具有良好性能。