2m望远镜主轴交流伺服控制系统设计

为了满足2m口径望远镜低速跟踪精度的要求,本文主要介绍了基于永磁同步力矩电机的望远镜交流伺服控制系统设计方法,首先,辨识出了系统结构的频率特性曲线;其次,根据系统的频率特性曲线设计了结构滤波器,以减小结构模态引起的谐振幅值;然后,根据系统的控制性能指标要求,设计了位置回路控制器和前馈控制器,以提高系统的位置跟踪性能;最后,在设计的硬件平台上进行了望远镜转台的低速控制实验。实验结果显示,当望远镜跟踪斜率为0.36″/s的位置斜坡曲线时,速度平稳性较好,位置跟踪误差RMS为0.006 1″,实现了极低速度跟踪的效果;在速度为5°/s,加速度为2°/s2条件下的正弦引导最大误差值为0.3″,稳态误差RMS值为0.066″。实验结果表明,2m口径望远镜交流伺服系统的设计满足了系统跟踪精度的要求,为大型望远镜交流伺服控制系统的设计提供了一定的参考。     

Adaptive output control of a mobile manipulator hanging from a quadcopter unmanned vehicle

This article summarizes the comprehensive design of an adaptive control that solves the trajectory tracking of a four-rotor unmanned aerial vehicle supplied by an own-designed grasping device. The controller design uses the regular proportional–derivative (PD) structure which is common to solve regulation, as well as tracking problems for robotic systems. The PD structure needs the estimation of the time-derivative to be exerted on-line. The super-twisting algorithm served to operate as a decentralized estimator of the derivatives for the tracking errors. The controller gains were adjusted by the differential laws aimed to track attainable reference trajectories. The adaptive strategy adjusts the controller gains enforcing the convergence of both the estimation and the tracking errors. A numerical example showed the observer/controller performance. A comparison with a classic non-adaptive PD controller confirms the effectiveness on the tracking task by the proposed design. In addition, a set of virtual numerical evaluations using the parameters of a real quadcopter system confirmed the performance benefits of the adaptive controller based on the PD structure aided with the estimation of the velocity obtained by the observer.     

Model tracking dual stochastic controller design under irregular internal noises

Although many methods about the control of irregular external noise have been introduced and implemented, it is still necessary to design a controller that will be more effective and efficient methods to exclude for various noises. Accumulation of errors due to model tracking, internal noises (thermal noise, shot noise and 1/f noise) that come from elements such as resistor, diode and transistor etc. in the circuit system and numerical errors due to digital process often destabilize the system and reduce the system performance. New stochastic controller is adopted to remove those noises using conventional controller simultaneously. Design method of a model tracking dual controller is proposed to improve the stability of system while removing external and internal noises. In the study, design process of the model tracking dual stochastic controller is introduced that improves system performance and guarantees robustness under irregular internal noises which can be created internally. The model tracking dual stochastic controller utilizing F-P-K stochastic control technique developed earlier is implemented to reveal its performance via simulation.     

直接驱动型机械手的变结构控制

针对直接驱动型机械手的随动控制问题,提出了一种基于滑动模态扰动观测器的变结构控制器.通过观测由系统的非线性、模型的不确定性和外来干扰所造成的广义扰动,将非线性、强耦合的机械手动力学系统线性化,并解耦为多个单输入、单输出线性系统.控制器的设计不再依赖于机械手的精确模型.在二连杆机械手上做的仿真研究表明,在负载大范围变化的条件下,采用滑动模态扰动观测器的控制系统,比全状态反馈的控制系统具有更好的鲁棒性.     

多边法激光三维坐标测量系统及其跟踪机构设计

为实现对空间目标三维坐标的测量,研究出一种基于多边法的激光三维坐标测量系统。系统使用了四路激光跟踪干涉仪,通过冗余设计使系统具有许多独到的功能特点。由于跟踪机构的性能对整个测量系统的影响大,为此设计了一种独立式跟踪机构。介绍了系统的工作原理和主要功能特点,论述了跟踪机构的工作原理、结构及其误差。对有关实验的方法、结果做了简要论述。     

一种带渐消因子的自适应“当前”统计模型

光电经纬仪对目标跟踪时,目标突发机动时的跟踪效果较差.为此设计了一种带渐消因子的自适应"当前"统计模型.引入渐消因子增强其对突发机动的自适应跟踪能力和其鲁棒性,改进的"当前"模型改善了普通"当前"模型对一般机动目标的跟踪性能.仿真结果表明,和一般"当前"统计模型算法相比,本文提出的算法明显提高了对目标突发机动的跟踪性能.     

Tracking control of robot manipulators via output feedback linearization

This paper presents a robot manipulator tracking controller based on output feedback linearization. A sliding mode perturbation observer (SPO) is designed to estimate unmeasurable states and system perturbations that involve system nonlinearities, disturbances and unmodelled dynamics. The use of SPO allows to input/output linearize and decouple the strongly coupled nonlinear robot manipulator system merely by the feedback of joint angles. The controller design does not need an accurate model of the robot manipulator. Simulation studies are undertaken based on a two-link robot manipulator to evaluate the proposed approach. The simulation results show that the proposed controller has more superior tracking control performance, with payload changing in a wide range, in comparison with a sliding mode controller (SMC) designed based on state feedback linearization with full states available. Selected from Journal of Shenzhen University (Science & Engineering), 2005, 22(3)     

Supervisory hybrid control of piezoelectric actuators utilized in tracking piecewise continuous trajectories

This article presents a supervisory hybrid control design for piezoelectric actuators utilized in tracking trajectories with intermittent jump discontinuities. We use a previously developed robust adaptive controller and a standard PID controller to construct this hybrid control strategy. We show that when the sub-controllers are used for step tracking, while primarily tuned for continuous trajectory tracking, large undesirable oscillations occur. Conversely, when the controllers are retuned for step tracking, their performance degrades in tracking high-frequency continuous trajectories. Thus, a supervisory hybrid controller is developed to track desired trajectories with occasional discontinuities, using both the robust adaptive and the PID controllers. The robust adaptive controller performs as the primary controller for tracking the continuous segments of the desired trajectory, while the PID controller is activated when the steps occur. Results indicate that the proposed supervisory hybrid controller outperforms both sub-controllers in tracking high-frequency trajectories with intermittent discontinuities.     

Vehicle active steering control research based on two-DOF robust internal model control

Because of vehicle’s external disturbances and model uncertainties, robust control algorithms have obtained popularity in vehicle stability control. The robust control usually gives up performance in order to guarantee the robustness of the control algorithm, therefore an improved robust internal model control(IMC) algorithm blending model tracking and internal model control is put forward for active steering system in order to reach high performance of yaw rate tracking with certain robustness. The proposed algorithm inherits the good model tracking ability of the IMC control and guarantees robustness to model uncertainties. In order to separate the design process of model tracking from the robustness design process, the improved 2 degree of freedom(DOF) robust internal model controller structure is given from the standard Youla parameterization. Simulations of double lane change maneuver and those of crosswind disturbances are conducted for evaluating the robust control algorithm, on the basis of a nonlinear vehicle simulation model with a magic tyre model. Results show that the established 2-DOF robust IMC method has better model tracking ability and a guaranteed level of robustness and robust performance, which can enhance the vehicle stability and handling, regardless of variations of the vehicle model parameters and the external crosswind interferences. Contradiction between performance and robustness of active steering control algorithm is solved and higher control performance with certain robustness to model uncertainties is obtained.     

机载光电跟踪测量设备的目标定位误差分析

光电跟踪和测量设备用于测量飞行器在空中的飞行轨迹,作为飞行器飞行性能的评价。随着现代技术的发展,对飞行器性能提出愈来愈高的要求,从而也对跟踪和测量飞行器飞行轨迹的光电跟踪和测量设备提出了相应的技术进步要求,特别是对其测量精度指标。如何做好和完善误差分析、误差分配和误差综合,成为研制更高性能的光电跟踪测量设备总体设计中的一个重要问题,贯穿从可行性论证、方案论证、方案设计、设计、制造、装调、直到试验等整个研制过程。就这一类设备中最为复杂的机载光电跟踪测量设备的目标定位误差(即3轴上的测量误差),通过建立从被测目标到地面中心测量站9个坐标系,进行31次线性变换,构造35个变量的统一测量方程;进行测量误差因素的分析和分配,以及用蒙特卡洛法来分析和计算系统的目标定位误差。     

Improving disturbance rejection of PI controllers by means of the magnitude optimum method

The magnitude optimum (MO) method provides a relatively fast and nonoscillatory closed-loop tracking response for a large class of process models frequently encountered in the process and chemical industries. However, the deficiency of the method is poor disturbance rejection when controlling low-order processes. In this paper, the MO criterion is modified in order to optimize disturbance rejection performance, while the tracking performance has been improved by an integral set-point filtering PI controller structure. The new tuning rules, referred to as the disturbance rejection magnitude optimum (DRMO) method, were applied to several different two-degrees-of-freedom PI controllers. The DRMO method has also been tested on several different representatives of process models. The results of experiments have shown that the proposed tuning method with the integral set-point filtering PI controller is quite efficient in improving disturbance rejection performance, while retaining tracking performance comparable to the original MO method.     

一类非自衡对象的最优PID控制

实际控制系统中输入控制对象的控制能量大小不可能是无限大的,本文对控制能量存在约束时一类非自衡对象的最优控制问题作了探讨.首先定义了一个包含跟踪误差和控制能量在内的积分平方性能指标,然后针对不同设计要求运用最优方法极小化该性能指标,从而导出2类PID控制器的解析设计方法,可使系统在控制能量约束条件下具有最优的控制性能.     

Submicrometer control of a traction drive using state feedback and estimation

Traction drives are direct-drive systems that are more sensitive to noise and disturbances than lead screws. Their performance using PID control is not always satisfactory. Therefore, there is a need to improve the tracking performance of traction drives while overcoming their inherent sensitivity to disturbances. To understand their behavior better, their operating characteristics are investigated and a system model is developed. Using this model, a state feedback regulator is designed. To eliminate steady-state errors to step commands and improve tracking performance, an outer PID loop is added. The performance of this controller is then compared with that of a PID controller. It is shown that the state feedback/PID scheme rejects disturbances more than three times as fast as the PID controller and reduces tracking errors by over 50%.     

正交基函数多项式实时拟合 在轴角编码器测速中的应用

提出了一种基于正交基函数的多项式实时拟合方法,并应用于轴角编码器测速,解决了常规算法中拟合多项式阶数大于3阶时法方程组容易出现病态,进而使测速精度降低的问题。光电跟踪测量设备地面目标跟踪实验表明,该算法通过对拟合处理后的角度值进行微分运算得到角速率,能有效地降低编码器角度输出中随机误差对测速的影响。在典型实验条件下,与采用同阶拟合多项式的常规方法进行了比对,前者的测速误差标准偏差为0.013 43°/s,后者为0.028 15°/s,采用本算法提高了编码器的测速精度,适合在工程上应用。     

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     

Attitude maneuver control of flexible spacecraft by observer-based tracking control

A constraint equation-based control law design for large angle attitude maneuvers of flexible spacecraft is addressed in this paper. The tip displacement of the flexible spacecraft model is prescribed in the form of a constraint equation. The controller design is attempted in the way that the constraint equation is satisfied throughout the maneuver. The constraint equation leads to a two-point boundary value problem which needs backward and forward solution techniques to satisfy terminal constraints. An observer-based tracking control law takes the constraint equation as the input to the dynamic observer. The observer state is used in conjunction with the state feedback control law to have the actual system follow the observer dynamics. The observer-based tracking control law eventually turns into a stabilized system with inherent nature of robustness and disturbance rejection in LQR type control laws.     

Fuzzy Torque Control of the Bionic Flexible Manipulator Actuated by Pneumatic Muscle Actuators

A bionic flexible manipulator driven by pneumatic muscle actuator(PMA) can better reflect the flexibility of the mechanism.Current research on PMA mainly focuses on the modeling and control strategy of the pneumatic manipulator system.Compared with traditional electro-hydraulic actuators,the structure of PMA is simple but possesses strong nonlinearity and flexibility,which leads to the difficulty in improving the control accuracy.In this paper,the configuration design of a bionic flexible manipulator is performed by human physiological map,the kinematic model of the mechanism is established,and the dynamics is analyzed by Lagrange method.A fuzzy torque control algorithm is designed based on the computed torque method,where the fuzzy control theory is applied.The hardware experimental system is established.Through the co-simulation contrast test on MATLAB and ADAMS,it is found that the fuzzy torque control algorithm has better tracking performance and higher tracking accuracy than the computed torque method,and is applied to the entity control test.The experimental results show that the fuzzy torque algorithm can better control the trajectory tracking movement of the bionic flexible manipulator.This research proposes a fuzzy torque control algorithm which can compensate the error more effectively,and possesses the preferred trajectory tracking performance.     

Robust discrete time tracking control using sliding surfaces

This paper deals with the robustness issues associated with the feedforward tracking control with respect to unmodeled plant uncertainties. Based on the Diophantine equation, a new discrete time sliding functions has been defined and utilized for the robust feedforward tracking control law. The robustness is achieved by using a sliding function-based nonlinear feedback. As for model/plant mismatches the plant order uncertainty and parameter uncertainty are taken into account for robustness analysis. Noncircular machining has been adopted as an application example of this algorithm. Through computer simulation it has been shown that the robust discrete time tracking control is effective for unmodeled plant uncertainties.     

位置跟踪系统的预测控制研究

在位置跟踪系统中,希望系统输出能快速,准确地跟随输入而变化。首先采用阶跃响应法建立了控制对象的数学模型,然后将预测控制的思想用于位置跟踪系统的控制,提出了位置控制器的一种设计方法,对有关设计参数的选择进行了讨论。并针对一快速成形系统的X轴永磁同步伺服电机的控制进行了仿真和实时控制实验研究,结果表明,所设计的控制器具有很好的跟踪性能和鲁棒性能。