Reliable Sliding-Mode Control for Markovian Jumping Systems Subject to Partial Actuator Degradation

In this work, a novel robust sliding-mode control (SMC) method has been provided for uncertain stochastic Markovian jumping systems subject to actuator degradation, such that the closed-loop system is globally asymptotically stable (with probability one). In the design of switching functions, a set of specified matrices are employed such that the connections among sliding surfaces corresponding to each mode are established. Then, a sliding-mode controller is synthesized to ensure the reachability of the specified switching surface despite actuator degradation and uncertainties. Finally, the simulation results illustrate the proposed method and the effectiveness.     

Trajectory Switching Control of Robotic Manipulators Based on RBF Neural Networks

In this paper, we discuss the trajectory switching neural control problem for the switching model of a serial n-joint robotic manipulator. The key feature of this paper is to provide the dual design of the control law for the developed adaptive switching neural controller and the associated robust compensation control law. RBF Neural Networks (NNs) are employed to approximate unknown functions of robotic manipulators and a robust controller is designed to compensate the approximation errors of the neural networks and external disturbance. Via switched multiple Lyapunov function method, the adaptive updated laws and the admissible switching signals have been developed to guarantee that the resulting closed-loop system is asymptotically Lyapunov stable such that the joint position follows any given bounded desired output signal. Finally, we give a simulation example of a two-joint robotic manipulator to demonstrate the proposed methods and make a comparative analysis.     

Hybrid Terminal Sliding-Mode Observer Design Method for a Permanent-Magnet Synchronous Motor Control System

This paper proposes a hybrid terminal sliding-mode observer based on the nonsingular terminal sliding-mode (NTSM) and the high-order sliding-mode (HOSM) for the rotor position and speed estimation in the permanent-magnet synchronous motor control system. An NTSM manifold is utilized to realize both fast convergence and better tracking precision. In addition, a derivative estimator is used to obtain the derivative of the sliding-mode function. Meanwhile, an HOSM control law is designed to guarantee the stability of the observer and eliminate the chattering, so that smooth back-electromotive-force (EMF) signals can be obtained without a low-pass filter. According to the back-EMF equations, the rotor position and speed of the motor can be calculated. Simulation and experimental results are presented to validate the proposed method.      

Antisway Tracking Control of Overhead Cranes With System Uncertainty and Actuator Nonlinearity Using an Adaptive Fuzzy Sliding-Mode Control

An adaptive fuzzy sliding-mode control (AFSMC) is presented for the robust antisway trajectory tracking of overhead cranes subject to both system uncertainty and actuator nonlinearity. First, a fuzzy sliding-mode control (FSMC) law is designed for the antisway trajectory tracking of the nominal plant. In association with a conventional trajectory tracking control law, this FSMC law guarantees asymptotic stability as well as improved transient response of the load sway dynamics while the trolley tracking error dynamics is rendered uniformly asymptotically stable. Second, a fuzzy uncertainty observer is designed to cope with system uncertainty as well as actuator nonlinearity present in an actual plant, and it is incorporated with the FSMC law for the development of the AFSMC law. In addition to stability analysis, the robust performance of the proposed AFSMC law is verified via numerical simulations and experiments.      

机械臂变指数趋近律滑模控制律设计

针对机械臂滑模控制中存在抖振的问题,采用改进趋近律的思想来设计滑模控制律,以达到有效抑制抖振的目的。在对滑模控制的特点和常用的指数趋近律进行分析的基础上,提出了一种变指数趋近律,并对其趋近性能进行了分析;结合机械臂动力学模型和改进的趋近律设计了相应的滑模控制策略,对其控制效果进行了验证。仿真结果表明,该控制策略不仅有效地抑制了系统的抖振,而且保证了机械臂系统对期望轨迹的快速跟踪性,进而提高了机械臂的工作性能。     

Fuzzy Sliding-Mode Control of Active Suspensions

In this paper, a robust fuzzy sliding-mode controller for active suspensions of a nonlinear half-car model is introduced. First, a nonchattering sliding-mode control is presented. Then, this control method is combined with a single-input–single-output fuzzy logic controller to improve its performance. The negative value of the ratio between the derivative of error and error is the input and the slope constant of the sliding surface of the nonchattering sliding-mode controller is the output of the fuzzy logic controller. Afterwards, a four-degree-of-freedom nonlinear half-car model, which allows wheel hops and includes a suspension system with nonlinear spring and piecewise linear damper with dry friction, is presented. The designed controllers are applied to this model in order to evaluate their performances. It has been shown that the designed controller does not cause any problem in suspension working limits. The robustness of the proposed controller is also investigated for different vehicle parameters. The results indicate the success of the proposed fuzzy sliding-mode controller.      

Sliding-Mode Tracking Control of Surface Vessels

A sliding-mode control law is presented and experimentally implemented for trajectory tracking of underactuated autonomous surface vessels. The control law is developed by introducing a first-order sliding surface in terms of surge tracking errors and a second-order surface in terms of lateral motion tracking errors. The resulting sliding-mode control law guarantees position tracking while the rotational motion remains bounded. The experimental vessel is a small boat with two propellers in an indoor pool. The position and orientation of the boat are measured using a camera that detects two infrared diodes attached near the front and back ends of the boat. A computer with a capture card processes the camera image to determine the position, calculates the control forces and their corresponding input voltages, and sends the control signals to wireless receivers on the vessel using a wireless transmitter. Several experiments are performed where the vessel accurately follows straight-line and circular trajectories.      

Application of Higher Order Sliding-Mode Concepts to a Throttle Actuator for Gasoline Engines

In this paper, the control of an electronic throttle valve based on second-order sliding-mode concepts is presented. The so-called twisting algorithm is chosen as the control law. It is shown that the tracking performance for discontinuous reference signals is significantly improved by introducing nonlinear damping by appropriately specifying the sliding surface. The control concept requires the measured plate angle as well as its time derivative, which is computed with the help of a robust exact differentiator. The effectiveness of the proposed concept, consisting of a twisting algorithm for control and supertwisting algorithm for differentiation, is demonstrated by experimental results.      

High-Order Sliding-Mode Control of Variable-Speed Wind Turbines

This paper deals with the power generation control in variable-speed wind turbines. These systems have two operation regions which depend on wind turbine tip speed ratio. A high-order sliding-mode control strategy is then proposed to ensure stability in both operation regions and to impose the ideal feedback control solution in spite of model uncertainties. This control strategy presents attractive features such as robustness to parametric uncertainties of the turbine. The proposed sliding-mode control approach has been validated on a 1.5-MW three-blade wind turbine using the National Renewable Energy Laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. Validation results show that the proposed control strategy is effective in terms of power regulation. Moreover, the sliding-mode approach is arranged so as to produce no chattering in the generated torque that could lead to increased mechanical stress because of strong torque variations.      

六开关三相Boost型整流器的电压滑模控制

三相PWM整流器功率因数校正实现的关键在于如何得到与输入电压同相位的输入电流,同时要保证当负载变化时,输出电压能够迅速地跟踪参考值并且稳定下来。首先根据六开关三相boost型整流器的物理模型,分别建立了以电感电流和电容电压为状态向量的数学方程,然后把静止三相坐标转换到旋转d-q坐标下进行电流内环的滞环控制,电压外环的滑模控制。通过仿真,表明该控制方法具有较强的鲁棒性和良好的动态特性,输入电流谐波较小。     

Dynamical Sliding-Mode Control of the Boost Inverter

The boost inverter is a device that is able to generate a sinusoidal voltage with an amplitude larger than the input voltage. Based on the idea of indirectly controlling the output voltage through the inductor current, a dynamical sliding-mode controller for the boost inverter is proposed in this paper. Unlike the usual approach of generating a sinusoidal voltage in both capacitors of the boost inverter, the strategy proposed in this paper focuses on generating a sinusoidal voltage on the load despite the voltage form of both capacitors. A consequence of doing so is that only the desired output voltage is required as reference to implement the controller. Furthermore, it has a fast response, is robust under load and input voltage variations, and yet, is remarkably simple to implement. Although it is strongly nonlinear, it can be implemented using standard electronics circuitry and only needs voltage measurements.      

High-Performance Position Control of Induction Motor Using Discrete-Time Sliding-Mode Control

A new way of induction-motor position control for high-performance applications is developed in this paper using discrete-time sliding-mode (DSM) control. In addition to the main DSM position controller, the proposed control structure includes an active disturbance estimator (ADE), in which a passive filter is replaced by another DSM-controlled subsystem, in order to improve system robustness and accuracy. Furthermore, the application of an ADE makes possible the design of both controllers using the knowledge of the nominal system only. Experiments have verified high efficiency of the proposed servo system under the influence of large parameter perturbations and external disturbances in the presence of unmodeled dynamics.      

滑模变结构控制在三电平变换器中的应用研究

滑模变结构控制策略具有鲁棒性强、算法简单、动态品质好等优点，为此，本文首次将滑模变结构控制策略引入到三电平变换器中。首先介绍了直接滑模控制策略，然后给出了三电平变换器直接滑模控制策略的设计方法，最后对滑模控制三电平变换器进行仿真分析，并和PWM控制三电平变换器做比较，仿真结果验证了滑模变结构控制策略可以大大提高变换器鲁棒性和动态品质。     

Buck三电平变换器中滑模控制应用研究

滑模变结构控制具有鲁棒性强,动态品质好等优点。文中以Buck三电平为例论述利用滑模变结构的理论分析,设计了Buck三电平变换器的方法,详细讨论了滑模面的选取对系统性能的影响,并进行了等效控制、稳定性和存在性的证明。最后将滑模控制buck三电平与传统的PWM控制Buck三电平变换器进行了仿真分析和比较。研究结果验证了滑模变结构控制策略可以大大提高变换器的鲁棒性和动态品质。     

异步电动机调速系统的滑模直接转矩控制方法

在交流调速技术中，直接转矩控制技术的特点是具有快速的动态响应特性和很强的鲁棒性，这种控制方法存在的问题是在稳态运行时会出现转矩和磁链的脉动。为了降低转矩和磁链的脉动，本文基于滑模控制方法介绍了一种新的直接转矩控制方法，其特点是继承了直接转矩控制方法的优点，同时降低了稳态时转矩和磁链脉动，改善了调速系统的低速性能。最后对整个调速系统进行了实验研究，实验的结果表明了这种控制方法的有效性。     

Complex Discretization Behaviors of a Simple Sliding-Mode Control System

In this brief, we show that discretization of a simple sliding-mode control system can lead to very complex behaviors. Theoretical results are derived to depict the intrinsic behaviors with simulations given for illustration.     

Six-DOF Impedance Control of Dual-Arm Cooperative Manipulators

In this paper, the problem of impedance control of dual-arm cooperative manipulators is studied. A general impedance control scheme is adopted, which encompasses a centralized impedance control strategy, aimed at conferring a compliant behavior at the object level, and a decentralized impedance control, enforced at the end-effector level, aimed at avoiding large internal loading of the object. Remarkably, the mechanical impedance behavior is defined in terms of geometrically consistent stiffness. The overall control scheme is based on a two-loop arrangement, where a simple proportional integral derivative inner motion loop is adopted for each manipulator, while an outer loop, using force and moment measurements at the robots wrists, is aimed at imposing the desired impedance behaviors. The developed control scheme is experimentally tested on a dual-arm setup composed of two 6-DOF industrial manipulators carrying a common object. The experimental investigation concerns the four different controller configurations that can be achieved by activating/deactivating the single impedance controllers.     

Distributed Simulation of Differential Algebraic Systems Using Optimal Sliding-Mode Control

In this paper, the optimal solution of differential algebraic equation (DAE) systems over a network of processors is investigated. A sliding-mode control (SMC) approach is used to enforce the algebraic constraints of the DAEs. Time delays associated with network communication give rise to a sliding-control problem with sensor time delays. A new approach is presented that decouples this problem into two independent problems. Using this property, a mixed H_infin optimization approach is applied to minimize errors. The results are applied to solve the problem of the optimal bandwidth allocation between the processors under the constraint of limited communication bandwidth. Experimental results for a distributed simulation application on a TDMA network demonstrate the validity of the approach     

Cascade Control of PM DC Drives Via Second-Order Sliding-Mode Technique

This paper presents a novel scheme for the speed/position control of permanent-magnet (PM) dc motor drives. A cascade-control scheme, based on multiple instances of a second-order sliding-mode-control (2-SMC) algorithm, is suggested, which provides accurate tracking performance under large uncertainty about the motor and load parameters. The overall control scheme is composed of three main blocks: 1) a 2-SMC-based velocity observer which uses only position measurements; 2) a 2-SMC-based velocity control loop that provides a reference command current; and 3) a 2-SMC-based current control loop generating the reference voltage. The proposed scheme has been implemented and tested experimentally on a commercial PM dc motor drive. The experimental results confirm the precise and robust performance and the ease of tuning and implementation, featured by the proposed scheme.      

Accurate Sliding-Mode Control of Pneumatic Systems Using Low-Cost Solenoid Valves

A control law is developed for an inexpensive pneumatic motion control system using four solenoid on/off valves and a position feedback sensor. A sliding-mode approach is used, which is well known for its tolerance for system uncertainties. In contrast to previous control laws, our approach does not use pulsewidth modulation. The control law has an energy-saving mode that saves electrical power, reduces chattering, and prolongs the valve's life. Our simulation and experimental results show that the proposed tracking control law performs very well with good tracking and relatively low steady-state position errors