重复控制及其在变速非圆车削中的应用

为了提高变速非圆车削中直线伺服单元的跟踪精度和鲁棒性，建立了变速非圆车削的进给驱动直线电机、运动控制目标函数、主轴变速、切削力等的数学模型，分析了主轴变速精度对直线伺服单元控制的影响。应用重复控制理论设计了适于直线伺服单元的重复控制器，给出了详细的设计过程和稳定性分析，对控制器的性能进行了仿真分析。结果表明，基于重复控制的直线伺服单元能很好地跟踪变速非圆车削中刀具运动的目标值，能抑制波动的切削力对跟踪精度的影响。     

基于自抗扰控制的变速非圆车削技术研究

为了抑制非圆截面工件加工时的颤振,将变速加工应用于非圆截面车削中,设计了变速车削系统结构,分析了变速车削抑制颤振、提高稳定性的机理,设计了适于变速非圆车削的直线伺服单元,单元控制采用自抗扰控制技术.车床控制系统采用PMAC(Programmable multi-axis controller)时基控制法,实现刀具驱动进给和工件变速旋转的协调控制,完成非圆截面的变速车削.结果表明,直线伺服单元能很好地跟踪刀具目标值,非圆截面车削加工精度和稳定性得到了提高.     

基于二次型性能指标的PMLSM单神经元自适应PID控制

为了满足数控机床用永磁直线同步电动机(PMLSM)位置伺服和速度控制的性能要求,抑制参数摄动和负载扰动等不确定因素对伺服单元的影响,在建立PMLSM数学模型的基础上,引入二次型性能指标,设计了单神经元自适应PID速度控制器.仿真结果表明,对于永磁直线同步电动机,采用该控制器获得的跟踪精度、响应速度和自适应性等方面具有明显的改善.     

集成制造系统中基于重复控制的直线伺服单元

重复控制的直线伺服单元主要适合于跟踪快速变化的周期性信号，其输出为期望的周期性直线机械运动。这种运动在ＣＩＭＳ上的自动化设备中较为常见。文章介绍了永磁直线伺服单元的机械结构及重复控制的基本原理；给出了重复控制的直线伺服单元的典型应用场合和实例。     

基于Windows 2000的非圆截面车削数控系统

提出了基于Windows 2000以及高速实时串行总线的非圆截面车削数控系统结构。系统由普通数控功能扩展非圆加工模块实现。PC机与信号接口板联合实现普通数控功能，数控系统的实时性在Windows 2000平台下通过设备驱动程序配合高速实时串行总线实现。为实现直径方向的高速往复运动，非圆截面车削通过在X方向叠加U轴来实现非圆车削的直线进给运动，由专用直线伺服模块完成。刀架进给机构采用超磁致伸缩直线位移驱动器。直线伺服模块跟踪主轴编码器角度确定非圆加工刀具进给量。数控系统在中凸变椭圆活塞表面加工生产线投入应用，加工结果证明了系统的实用性。     

基于PCI的直线伺服控制系统在非圆加工中的应用研究

快速伺服刀架是非圆加工过程中非圆截面生成的关键部件,要求控制系统具有很高的响应频率和实时性能。文章设计了一种基于PCI总线的直线伺服控制系统,采用双口RAM进行DSP与上位机之间的高速通信,并实现快速刀架的精密位置跟踪控制。对控制器的硬件结构及软件系统进行了设计,实验结果表明设计的直线伺服控制系统能够满足非圆加工的需求。     

直线伺服系统时滞参数辨识与补偿研究

为解决直线伺服固有时滞特性对轨迹跟踪性能的影响,以典型的前馈加反馈二自由度控制结构为基础,分析直线伺服时滞特性对其轨迹跟踪精度的影响。在此基础上设计了前馈环节上的时滞控制器,之后针对时滞控制器位于前馈通道时作为一个超前环节控制上无法实现的问题,将时滞参数分为两部分,分别调节理想轨迹指令按照整数倍伺服周期延时及前馈控制信号滤波延时以达到时滞补偿的目的,引入牛顿迭代寻优进行最优时滞参数辨识。仿真与试验结果表明,在前馈加反馈二自由度控制的基础上加入时滞控制器可以有效减小直线伺服系统的闭环位置跟踪误差,特别是显著减小非零加加速度段的闭环位置跟踪误差,提高轨迹跟踪性能。     

新型直线回转式快刀伺服装置的性能测试与分析

基于快刀伺服的金刚石车削技术是光学自由曲面、非圆柱面和微结构表面等方面高效率、高精度的加工技术,受到国内外的广泛关注。在该技术中,随着被加工曲面面型的变化,刀具的瞬态工作前角会实时发生变化,而影响刀具磨损、切削力的变化以及切削稳定性。设计一套直线回转式快刀伺服装置,可在自由曲面车削中实现刀具工作前角的调整。该装置实现了亚微米级的工作精度和10nm的运动分辨率。试验测试的结果表明该装置具有了良好的工作性能。     

垂直运动永磁同步直线电机的复合控制研究

为了改善永磁同步直线电机在数控珩磨机主轴往复运动时的伺服性能,建立了永磁同步直线电机的数学模型。通过对直线电机运动系统数学模型进行分析,得出系统参数摄动、推力波动、负载扰动等不确定因素是造成控制性能下降的主要因素。提出以典型三闭环PID控制、前馈控制和干扰观测器相结合的复合控制结构来提高系统的控制性能,并对控制器进行设计。在MATLAB中对控制系统进行建模和仿真,仿真结果表明,采用复合控制后,系统可以达到较好的抗干扰效果,基本上消除了响应滞后,能准确的跟踪输入信号。     

凸轮数控车削系统关键技术的研究

研究了基于数控车削加工凸轮的方法,并对数控车削凸轮的关键技术进行研究,提出了有效的方法,为凸轮的高效率加工提供了一个新的途径。一般在凸轮数控车削加工过程中,切削角与切削速度随加工凸轮轮廓位置不同会发生很大变化,为了实现切削角随凸轮轮廓位置实时变化,采用了高频响直线伺服电动机驱动刀具高频摆动的方法,实现刀具的位置实时控制。凸轮的轮廓是一个非圆截面,为了生成凸轮非圆截面,采用高频响直线伺服电动机驱动刀具往复高速运动,实现凸轮非圆截面的生成。车削凸轮时,切削速度一般需要保持恒定,这样有利于刀具的寿命延长,并保证凸轮表面的粗糙度,为了实现凸轮车削的恒定线速度,采用变主轴转速的车削方法,解决这个重要的切削工艺问题。     

Design,implementation, and test of skid steering-based autonomous driving controller for a robotic vehicle with articulated suspension

This paper describes an autonomous driving control algorithm based on skid steering for a Robotic Vehicle with Articulated Suspension (RVAS). The driving control algorithm consisted of four parts: speed controller for following the desired speed, trajectory tracking controller to track the desired trajectory, longitudinal tire force distribution algorithm which determines the optimal desired longitudinal tire force and wheel torque controller which determines the wheel torque command at each wheel to keep the slip ratio below the limit value as well as to track the desired tire force. The longitudinal and vertical tire force estimators were designed for optimal tire force distribution and wheel slip control. The dynamic model of the RVAS is validated using vehicle test data. Simulation and vehicle tests were conducted in order to evaluate the proposed driving control algorithm. Based on the simulation and test results, the proposed driving controller was shown to produces satisfactory trajectory tracking performance.     

Practical motion control with acceleration reference for precision motion—New NCTF control and its application to non-contact mechanism

This paper presents an improved practical controller for enhancing precision motion performance. For practical use, high motion control performance and ease of controller design are desired. A nominal characteristic trajectory following control (NCTF control) has been studied to satisfy the desired response. The NCTF controller consists of a nominal characteristic trajectory (NCT) which is the reference motion of control system and a compensator which makes the motion of the controlled object to follow the NCT. The NCT is easily determined from experimental open-loop time responses of the mechanism. The controller parameters can be also determined easily, without any given model parameters. In the present paper, the Continuous Motion NCTF controller for high continuous motion performance is improved in order to enhance the following characteristic of the object motion on NCT and improve the positioning and tracking accuracies of the system. The improved Continuous Motion NCTF controller (referred to as Acceleration Reference-Continuous Motion NCTF controller (AR-CM NCTF controller)) provides the advantages such as the high overshoot reduction characteristics and the low sensitivity disturbance. The AR-CM NCTF controller includes the structure of the Continuous Motion NCTF controller and acceleration reference for the object motion as the additional controller elements. The design procedure of the AR-CM NCTF controller remains easy and practical. In order to confirm the advantages, the AR-CM NCTF controller was examined in positioning and tracking motion performances using the non-contact mechanism. The experimental results prove that the AR-CM NCTF controller achieves the better positioning and tracking performances than the Continuous Motion NCTF controller.     

电机波动力矩的重复学习控制补偿

为较好地解决伺服系统的低速抖动问题,研究了重复学习控制方法抑制电机波动力矩等非线性干扰,以提高系统的低速平稳性问题。在讨论电机波动力矩成因的基础上,重点研究了电机齿槽效应引起的电机力矩波动的理论模型、量值大小等问题,并在模型转台上进行了实验测试。实验结果表明了理论分析的正确性,并证明了电机波动力矩的周期性。根据上述结论,引用重复学习控制来抑制这种周期性干扰,介绍了带有低通滤波器和前馈滤波器的改进型重复学习控制器的设计方法,设计了实际的控制系统。对采用重复学习控制的伺服系统进行正弦跟踪实验测试,结果说明,重复学习控制较好地补偿了低速或零速附近的系统死区特性,系统的跟踪误差最大值为0.72″。     

Adaptive Robust Tracking Control of Pressure Trajectory Based on Kalman Filter

When adaptive robust control(ARC) strategy based on backstepping design is applied in pneumatic servo control, accurate pressure tracking in motion is especially necessary for both force and position trajectories tracking of rodless pneumatic cylinders, and therefore an adaptive robust pressure controller is developed in this paper to improve the tracking accuracy of pressure trajectory in the chamber when the pneumatic cylinder is moving. In the proposed adaptive robust pressure controller, off-line fitting of the orifice area and on-line parameter estimation of the flow coefficient are utilized to have improved model compensation, and meanwhile robust feedback and Kalman filter are used to have strong robustness against uncertain nonlinearities, parameter fluctuations and noise. Research results demonstrate that the adaptive robust pressure controller could not only track various pressure trajectories accurately even when the pneumatic cylinder is moving, but also obtain very smooth control input, which indicates the effectiveness of adaptive model compensation. Especially when a step pressure trajectory is tracked under the condition of the movement of a rodless pneumatic cylinder, maximum tracking error of ARC is 4.46 kPa and average tracking error is 0.99 kPa, and steady-state error of ARC could achieve 0.84 kPa, which is very close to the measurement accuracy of pressure transducer.     

基于线性时变模型预测控制的自主车辆轨迹跟踪控制器设计与验证

随着自动驾驶技术的快速发展,精确的轨迹跟踪已经成为汽车工业和学术领域公认的实现自主车辆运动控制的核心技术之一。为提高自主车辆轨迹跟踪的实时性与准确性,提出一种应用于自主车辆的线性时变模型预测跟踪控制器（Linear time-varying model predictive controller,LTV-MPC）设计方法。根据运动学原理建立某自主无人小车的二自由度运动学模型,其次,基于该模型构建车辆轨迹跟踪系统的误差模型并利用线性参数化理论对其进行离散化,在模型预测控制框架内将该轨迹跟踪控制器的设计转化为一个线性二次规划最优问题。在一个实际搭建的自主车辆试验平台上对所提出控制器的有效性进行不同预设参考路径轨迹下的实车验证,结果表明,该自主车辆能够对所预设的实际参考道路轨迹进行快速、准确的轨迹跟踪控制,且具有较好的行驶稳定性能。     

Adaptive robust motion trajectory tracking control of pneumatic cylinders with LuGre model-based friction compensation

Friction compensation is particularly important for motion trajectory tracking control of pneumatic cylinders at low speed movement. However, most of the existing model-based friction compensation schemes use simple classical models, which are not enough to address applications with high-accuracy position requirements. Furthermore, the friction force in the cylinder is time-varying, and there exist rather severe unmodelled dynamics and unknown disturbances in the pneumatic system. To deal with these problems effectively, an adaptive robust controller with LuGre model-based dynamic friction compensation is constructed. The proposed controller employs on-line recursive least squares estimation（RLSE） to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbances. In addition, in order to realize LuGre model-based friction compensation, the modified dual-observer structure for estimating immeasurable friction internal state is developed. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology is applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping is used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Finally, the proposed controller is tested for tracking sinusoidal trajectories and smooth square trajectory under different loads and sudden disturbance. The testing results demonstrate that the achievable performance of the proposed controller is excellent and is much better than most other studies in literature. Especially when a 0.5 Hz sinusoidal trajectory is tracked, the maximum tracking error is 0.96 mm and the average tracking error is 0.45 mm. This paper constructs an adaptive robust controller     

基于轨迹控制的AGV运动控制器设计研究

对基于计算机视觉的AGV路径跟踪技术进行了研究,提出了基于轨迹控制的AGV运动控制器设计新方法,重点解决AGV路径跟踪效果与高速运动稳定性问题。首先对AGV工作环境与计算机视觉的特点进行分析,设计了适合AGV路径跟踪的图像处理流程。然后在深入分析两轮差速驱动运动平台的基础上,提出了基于轨迹控制的AGV运动控制器设计新方法。该控制器以AGV相对路径所处的状态量为输入,输出AGV控制指令——两轮的速度差和运动时间,从而控制AGV按指定轨迹运动,实现轨迹控制即AGV路径跟踪的目标。试验结果表明,AGV路径跟踪技术对直线和弧线具有较好的跟踪效果且AGV运动平稳。     

Disturbance observer and adaptive controller design for a linear-motor-driven table system

This paper presents a disturbance observer and adaptive controller design for a direct drive motion control system. An indirect adaptive controller is implemented to achieve desired tracking performance as well as deal with system parameters variation. To reduce tracking errors, a newly designed adaptive feed-forward controller is proposed based on an on-line estimated inverse model of the linear motor drive system. A digital disturbance observer is implemented to be included in the proposed feedback-feed-forward control structure to compensate for the undesired nonlinearity and external load disturbance of the direct drive system. Experimental results show that this control scheme can achieve superior contouring accuracy, disturbance rejection and robustness under the influence of friction and cogging force.     

2R耦合驱动关节动力学建模与参数辨识

围绕护理机器人的人机安全接触和轻量大负载需求,提出了一种2R耦合驱动关节构型,并解决了耦合驱动动力学建模问题,为高性能运动控制器搭建提供基础。该关节设计紧凑、负载能力强,两个伺服电机经过三级减速后,通过差动结构实现两自由度耦合输出,且表面光滑适宜与人接触。通过运动学分析了耦合驱动的原理,利用拉格朗日法建立了耦合驱动动力学模型。为解决速度零点摩擦力不连续,造成基于模型的控制器运动性能变差的问题,引入了连续可微摩擦模型,利用连续可微特性采用灰色模型提高了辨识精度。研制了机器人关节样机,进行了关节解耦、摩擦数据采集、参数辨识及轨迹跟踪等试验,结果表明所设计的耦合驱动关节可以完成周转、俯仰两个转动自由度的单独及耦合运动,并且输出扭矩与重量的比值达到了143.6 N·m/kg,可以满足轻量大负载护理需求,同时基于所建立动力学模型的运动控制可以显著提高轨迹跟踪的准确性。