A Novel Disturbance Observer Based Fixed-Time Sliding Mode Control for Robotic Manipulators With Global Fast Convergence

This paper proposes a new global fixed-time sliding mode control strategy for the trajectory tracking control of uncertain robotic manipulators.First,a fixed-time disturbance observer(FTDO) is designed to deal with the adverse effects of model uncertainties and external disturbances in the manipulator systems.Then an adaptive scheme is used and the adaptive FTDO(AFTDO) is developed,so that the priori knowledge of the lumped disturbance is not required.Further,a new non-singular fast terminal sliding mode(NFTSM) surface is designed by using an arctan function,which helps to overcome the singularity problem and enhance the robustness of the system.Based on the estimation of the lumped disturbance by the AFTDO,a fixed-time non-singular fast terminal sliding mode controller(FTNFTSMC)is developed to guarantee the trajectory tracking errors converge to zero within a fixed time.The settling time is independent of the initial state of the system.In addition,the stability of the AFTDO and FTNFTSMC is strictly proved by using Lyapunov method.Finally,the fixed-time NFESM(FTNFTSM) algorithm is validated on a 2-link manipulator and comparisons with other existing sliding mode controllers(SMCs) are performed.The comparative results confirm that the FTNFTSMC has superior control performance.

Design of integral sliding mode guidance law based on disturbance observer

With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.

Trajectory tracking guidance of interceptor via prescribed performance integral sliding mode with neural network disturbance observer

This paper investigates interception missiles’trajectory tracking guidance problem under wind field and external disturbances in the boost phase.Indeed,the velocity control in such trajectory tracking guidance systems of missiles is challenging.As our contribution,the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy.The global prescribed performance function,which guarantees the tracking error within the set range and the global convergence of the tracking guidance system,is first proposed based on the traditional PPF.Then,a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities.Meanwhile,an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem.A back propagation neural network(BPNN)extended state observer(BPNNESO)is employed in the inner loop to identify disturbances.The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors,convergence times,and overshoots.

温度自适应SMO算法估计锂离子电池的SOC

现有对锂离子电池荷电状态(SOC)的估计,没有考虑温度变化导致的SOC估计准确度降低。提出一种考虑温度的滑模观测(SMO)法进行SOC估计。基于混合脉冲功率测试(HPPC)实验的数据,得到18650型LiFePO4锂离子电池的SOC与温度、参数之间的拟合式,通过台风(Typhoon)系统进行半实物实验分析。温度自适应SMO算法在低温或常温工况下的平均误差较传统SMO算法降低0.3~0.5个百分点,直接通过拟合式所快速估计的SOC较温度自适应SMO算法平均误差在2%左右,常温25℃工况下误差低于1%,能够实现较高的估计精准度,为快速估计SOC提供了较好的算法参考。

改进STSMO的PMSM无传感器直接转矩控制系统

为提高滑模观测器转子位置观测精度,抑制抖振频发,提出了一种基于超螺旋滑模观测器(STSMO)的双重滤波直接转矩(DTC)控制方法。传统滑模观测器为了提取连续的扩展反电动势估计值,通常需要外加一个低通滤波器滤除高频信号,采用STSMO来提取反电动势,在低通滤波器前提下增加了卡尔曼滤波器,形成双重滤波结构,进一步滤除噪声和干扰信号,减小估算反电动势中的纹波,同时用饱和函数替代原有的符号函数以减小抖振。实验和仿真结果证明,改进STSMO控制系统能有效抑制系统抖振,具有更好的控制精度和稳态品质。

基于改进型SMO无位置传感器速度控制

针对传统SMO(Sliding Mode Observer)在开关函数切换过程中存在抖振现象,提出一种利用饱和函数代替开关函数的新型滑模观测器削弱抖振,并在位置信息提取过程中选用锁相环代替传统的反正切方法,从而提高对PMSM(Permanent-Magnet Synchronous Motor)转子位置的观测精度。在Matlab环境下,通过传统和新型SMO的对比,可观察到转子的转速误差提高了大约14 r/min,转子位置误差提高大约0.03 rad。

Backstepping Sliding Mode Control Based on Extended State Observer for Hydraulic Servo System

Hydraulic servo system plays an important role in industrial fields due to the advantages of high response,small size-to-power ratio and large driving force.However,inherent nonlinear behaviors and modeling uncertainties are the main obstacles for hydraulic servo system to achieve high tracking perfor-mance.To deal with these difficulties,this paper presents a backstepping sliding mode controller to improve the dynamic tracking performance and anti-interfer-ence ability.For this purpose,the nonlinear dynamic model is firstly established,where the nonlinear behaviors and modeling uncertainties are lumped as one term.Then,the extended state observer is introduced to estimate the lumped distur-bance.The system stability is proved by using the Lyapunov stability theorem.Finally,comparative simulation and experimental are conducted on a hydraulic servo system platform to verify the efficiency of the proposed control scheme.

基于HCCSMO的永磁同步直线电机无传感器控制

基于滑模观测器(SMO)的永磁同步直线电机(PMSLM)无传感器控制存在抖振和估计反电动势谐波,会造成速度和位置的估计误差。为解决上述问题,提出了一种谐波交叉消除滑模观测器(HCCSMO)。首先采用Sigmoid函数替代符号函数以削弱抖振,然后引入谐波交叉消除二阶广义积分器(SOGI)代替低通滤波器对估计反电动势进行处理,抑制由定位力产生的谐波分量,减小SMO的速度与位置估计误差。仿真与实验结果均表明所提出的方法能够有效抑制SMO的估计误差,提高速度和位置观测精度。

基于改进型SMO的PMSM无传感器控制研究

针对传统滑模观测器(SMO)对永磁同步电机(PMSM)反电动势估计存在高频抖动而导致位置和转速误差较大的问题,分析设计了一种新型滑模观测器。首先,从滑模变结构控制原理出发,分析了传统SMO中控制函数的不足,其次,设计了新型控制函数,改善传统滑模观测器因使用开关函数造成估算值抖动过大的问题;同时使用频率自适应复系数滤波器代替传统的低通滤波器,提升估计转子位置和转速的精度。最后,在Matlab/Simulink平台搭建了算法仿真,仿真结果表明,该观测器能够很好地观测跟踪电机转速和其转子位置,能有效抑制高频抖振,提高滑模观测器估算精度,提高了PMSM无传感控制系统的稳定性。

基于改进SMO的PMSM无传感器控制

由于传统滑模观测器(SMO)中控制函数采用具有不连续性的符号函数(sign),导致SMO采集到永磁同步电机(PMSM)的反电动势存在严重的高频抖振,进而使得转子位置估计值与转子位置实际值存在较大的偏差。为了提高PMSM无传感器控制精度,提出了一种基于新型控制函数的改进SMO,采用具有连续性的控制函数■(s)作为SMO的控制函数,利用锁相环(PLL)提取转子位置信息,以减小系统抖振,提高转子位置估计精度。同时,根据李雅普诺夫稳定性判据(Lyapunov)对系统的稳定性进行了验证。最后,基于Matlab/Simulink软件的仿真结果表明,提出的改进SMO有效降低了PMSM反电动势的抖振,提高了PMSM无传感控制系统的控制精度。

Observer-based robust high-order fully actuated attitude autopilot design for spinning glide-guided projectiles

This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.

基于改进PLL的永磁同步电机ASMO无传感器控制

永磁同步电机无位置传感器控制采用传统滑模观测器法来获取转子位置,由于滑模抖振严重、估计反电势中含有低次谐波干扰及传统锁相环在电机反转时有位置误差等因素,影响转子位置估计精度。通过设计自适应滑模观测器和改进锁相环来解决上述问题。首先采用非奇异快速终端滑模面及改进指数趋近律来降低滑模抖振。其次对传统锁相环鉴相器进行改进并在环路滤波器中引入二阶广义积分器,不仅使电机正反转时能准确提取转子位置信息,还能滤除估计反电势中的低次谐波。仿真结果表明所设计的算法能减小滑模抖振、降低位置跟踪延迟时间及提高位置观测精度。

Disturbance observer based time-varying sliding mode control for uncertain mechanical system

It is now well known that the time-varying sliding mode control （TVSMC） is characterized by its global robustness against matched model uncertainties and disturbances. The accurate tracking problem of the mechanical system in the presence of the parametric uncertainty and external disturbance is addressed in the TVSMC framework. Firstly, an exponential TVSMC algorithm is designed and the main features are analyzed. Especially, the control parameter is obtained by solving an optimal problem. Subsequently, the global chattering problem in TVSMC is considered. To reduce the static error resulting from the continuous TVSMC algorithm, a disturbance observer based time-varying sliding mode control （DOTVSMC） algorithm is presented. The detailed design principle and the stability of the closed-loop system under the composite controller are provided. Simulation results verify the effectiveness of the proposed algorithm.

Robust Adaptive Gain Higher Order Sliding Mode Observer Based Control-constrained Nonlinear Model Predictive Control for Spacecraft Formation Flying

This work deals with the development of a decentralized optimal control algorithm, along with a robust observer,for the relative motion control of spacecraft in leader-follower based formation. An adaptive gain higher order sliding mode observer has been proposed to estimate the velocity as well as unmeasured disturbances from the noisy position measurements.A differentiator structure containing the Lipschitz constant and Lebesgue measurable control input, is utilized for obtaining the estimates. Adaptive tuning algorithms are derived based on Lyapunov stability theory, for updating the observer gains,which will give enough flexibility in the choice of initial estimates.Moreover, it may help to cope with unexpected state jerks. The trajectory tracking problem is formulated as a finite horizon optimal control problem, which is solved online. The control constraints are incorporated by using a nonquadratic performance functional. An adaptive update law has been derived for tuning the step size in the optimization algorithm, which may help to improve the convergence speed. Moreover, it is an attractive alternative to the heuristic choice of step size for diverse operating conditions. The disturbance as well as state estimates from the higher order sliding mode observer are utilized by the plant output prediction model, which will improve the overall performance of the controller. The nonlinear dynamics defined in leader fixed Euler-Hill frame has been considered for the present work and the reference trajectories are generated using Hill-Clohessy-Wiltshire equations of unperturbed motion. The simulation results based on rigorous perturbation analysis are presented to confirm the robustness of the proposed approach.

Fixed-time Sliding Mode Formation Control of AUVs Based on a Disturbance Observer

In this paper,we investigate formation tracking control of autonomous underwater vehicles(AUVs)with model parameter uncertainties and external disturbances.The external disturbances due to the wind,waves,and ocean currents are combined with the model parameter uncertainties as a compound disturbance.Then a disturbance observer(DO)is introduced to estimate the compound disturbance,which can be achieved within a finite time independent of the initial estimation error.Based on a DO,a novel fixed-time sliding control scheme is developed,by which the follower vehicle can track the leader vehicle with all the states globally stabilized within a given settling time.The effectiveness and performance of the method are demonstrated by numerical simulations.

Continuous Sliding Mode Controller with Disturbance Observer for Hypersonic Vehicles

In this paper, a continuous sliding mode controller with disturbance observer is proposed for the tracking control of hypersonic vehicles to suppress the chattering. The finite time disturbance observer is involved to make that the continuous sliding mode controller has the property of disturbance rejection.Due to continuous terms replacing the discontinuous term of traditional sliding mode control, switching modes of velocity and altitude firstly arrive at small regions with respect to disturbance observation errors. Switching modes keep zero and velocity and altitude asymptotically converge to their reference commands after disturbance observation errors disappear. Simulation results have proved the proposed method can guarantee the tracking of velocity and altitude with continuous sliding mode control laws,and also has the fast convergence rate and robustness.

Target Tracking Algorithm Using Finite-time Convergence Smooth Second-order Sliding Mode Controller for Mobile Robots

Target tracking control for wheeled mobile robot （WMR） need resolve the problems of kinematics model and tracking algorithm.High-order sliding mode control is a valid method used in the nonlinear tracking control system,which can eliminate the chattering of sliding mode control.Currently there lacks the research of robustness and uncertain factors for high-order sliding mode control.To address the fast convergence and robustness problems of tracking target,the tracking mathematical model of WMR and the target is derived.Based on the finite-time convergence theory and second order sliding mode method,a nonlinear tracking algorithm is designed which guarantees that WMR can catch the target in finite time.At the same time an observer is applied to substitute the uncertain acceleration of the target,then a smooth nonlinear tracking algorithm is proposed.Based on Lyapunov stability theory and finite-time convergence,a finite time convergent smooth second order sliding mode controller and a target tracking algorithm are designed by using second order sliding mode method.The simulation results verified that WMR can catch up the target quickly and reduce the control discontinuity of the velocity of WMR.

Decoupling Adaptive Sliding Mode Observer Design for Wind Turbines Subject to Simultaneous Faults in Sensors and Actuators

This paper proposes an adaptive sliding mode observer(ASMO)-based approach for wind turbines subject to simultaneous faults in sensors and actuators.The proposed approach enables the simultaneous detection of actuator and sensor faults without the need for any redundant hardware components.Additionally,wind speed variations are considered as unknown disturbances,thus eliminating the need for accurate measurement or estimation.The proposed ASMO enables the accurate estimation and reconstruction of the descriptor states and disturbances.The proposed design implements the principle of separation to enable the use of the nominal controller during faulty conditions.Fault tolerance is achieved by implementing a signal correction scheme to recover the nominal behavior.The performance of the proposed approach is validated using a 4.8 MW wind turbine benchmark model subject to various faults.Monte-Carlo analysis is also carried out to further evaluate the reliability and robustness of the proposed approach in the presence of measurement errors.Simplicity,ease of implementation and the decoupling property are among the positive features of the proposed approach.

Consensus of second-order nonlinear multi-agent systems via sliding mode observer and controller

This paper investigates the consensus problem of second-order nonlinear multi-agent systems (MASs) via the sliding mode control (SMC) approach. The velocity of each agent is assumed to be unmeasurable. A second-order sliding mode observer is designed to estimate the velocity. Then a distributed discontinuous control law based on first-order SMC is presented to solve the consensus problem. Moreover, to overcome the chatting problem, two controllers based on the boundary layer method and the super-twisting algorithm respectively are presented. It is shown that the MASs will achieve consensus under some given conditions. Some examples are provided to demonstrate the effectiveness of the proposed control laws.

驱动高速开关的无刷直流电机SMO-ANF-DTC方法

无刷直流电机具有高效率和低噪声优点,在高速开关(high speed switch,HSS)的驱动方面具有良好的应用前景,但是电机转矩脉动会影响高速开关的稳态和动态调控性能。为此,研究了一种基于优化滑模观测器-自适应陷波器-直接转矩控制(SMO-ANF-DTC)的转矩脉动抑制方法。通过构建外环速度环和内环电流环的双闭环控制提升系统的精确度和抗干扰能力;在直接转矩控制基础上加入优化滑模观测器和自适应滤波器,进行电机驱动的谐波抑制。该控制方法在进行转矩脉动抑制的同时,提升了电机控制的精度和稳定性。通过仿真对比了传统控制策略与提出控制策略的相电流波形和转矩波形,在使用SMO-ANF-DTC控制方法后,相电流输出波形与转矩波形顶部的波动明显减少。结果表明所提出的控制策略能够提升电机的性能。