Sliding Mode Control With Perturbation Estimation (SMCPE) and Frequency Shaped Sliding Surfaces

1997 ◽  
Vol 119 (3) ◽  
pp. 584-588 ◽  
Author(s):  
Jairo T. Moura ◽  
Rajiv Ghosh Roy ◽  
Nejat Olgac
Keyword(s):  
Sliding Mode Control ◽  
Upper Bound ◽  
Sliding Mode ◽  
A Priori ◽  
Tracking Errors ◽  
Mode Control ◽  
Uncertain Dynamic Systems ◽  
Estimation Scheme ◽  
Frequency Components ◽  
Perturbation Estimation

Sliding Mode Control with Perturbation Estimation (SMCPE) is a recent control routine which steers uncertain dynamic systems with disturbances to follow a desired trajectory. It eliminates the conventional requirement for the knowledge of uncertainty upper bound. A perturbation estimation scheme provides a tool for robustness. This text offers an additional robustizing mechanism: selection of time-varying sliding functions utilizing frequency shaping techniques. Frequency shaping together with sliding mode control introduces a behavior for selectively penalizing tracking errors at certain frequency ranges. This combination provides two advantages concurrently: (a) It filters out certain frequency components of the perturbations therefore eliminating the possible excitation on the unmodelled dynamics, and (b) it drives the state to the desired trajectory despite perturbations. The crucial point is that a priori knowledge of the perturbation upper bound is not necessary to eliminate the perturbation effects at the designated frequencies. Numerical examples prove the effectiveness of this novel scheme.

Sliding Mode Control of an Actuated Knee Joint Orthosis

2021 ◽  
Vol 15 ◽  
Author(s):  
Imen Saidi ◽  
Asma Hammami
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Sliding Mode ◽  
Position Tracking ◽  
Sliding Mode Controller ◽  
Mechanical Device ◽  
Tracking Errors ◽  
Mode Control ◽  
Speed Tracking ◽  
Human Morphology

Introduction: In this paper, a robust sliding mode controller is developed to control an orthosis used for rehabilitation of lower limb. Materials and Methods: The orthosis is defined as a mechanical device intended to physically assist a human subject for the realization of his movements. It should be adapted to the human morphology, interacting in harmony with its movements, and providing the necessary efforts along the limbs to which it is attached. Results: The application of the sliding mode control to the Shank-orthosis system shows satisfactory dynamic response and tracking performances. Conclusion: In fact, position tracking and speed tracking errors are very small. The sliding mode controller effectively absorbs disturbance and parametric variations, hence the efficiency and robustness of our applied control.

scholarly journals Finite-Time Adaptive Higher-Order SMC for the Nonlinear Five DOF Active Magnetic Bearing System

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1333
Author(s):  
Sudipta Saha ◽  
Syed Muhammad Amrr ◽  
Abdelaziz Salah Saidi ◽  
Arunava Banerjee ◽  
M. Nabi
Keyword(s):  
Sliding Mode Control ◽  
Finite Time ◽  
Sliding Mode ◽  
A Priori ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Mode Control ◽  
Adaptive Laws ◽  
Effective Performance ◽  
Unknown Disturbances

The active magnetic bearings (AMB) play an essential role in supporting the shaft of fast rotating machines and controlling the displacements in the rotors due to the deviation in the shaft. In this paper, an adaptive integral third-order sliding mode control (AITOSMC) is proposed. The controller suppresses the deviations in the rotor and rejects the system uncertainties and unknown disturbances present in the five DOF AMB system. The application of AITOSMC alleviates the problem of high-frequency switching called chattering, which would otherwise restrict the practical application of sliding mode control (SMC). Moreover, adaptive laws are also incorporated in the proposed approach for estimating the controller gains. Further, it also prevents the problem of overestimation and avoids the use of a priori assumption about the upper bound knowledge of total disturbance. The Lyapunov and homogeneity theories are exploited for the stability proof, which guarantees the finite-time convergence of closed-loop and output signals. The numerical analysis of the proposed strategy illustrates the effective performance. Furthermore, the comparative analysis with the existing control schemes demonstrates the efficacy of the proposed controller.

Observer-based sliding mode control with adaptive perturbation estimation for micropositioning actuators

2011 ◽  
Vol 35 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Hamed Ghafarirad ◽  
Seyed Mehdi Rezaei ◽  
Amir Abdullah ◽  
Mohammad Zareinejad ◽  
Mozafar Saadat
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Mode Control ◽  
Perturbation Estimation

scholarly journals Experimental Validation of a Sliding Mode Control for a Stewart Platform Used in Aerospace Inspection Applications

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 2051
Author(s):  
Javier Velasco ◽  
Isidro Calvo ◽  
Oscar Barambones ◽  
Pablo Venegas ◽  
Cristian Napole
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
A Priori ◽  
Absolute Error ◽  
Stewart Platform ◽  
System Stability ◽  
Pi Control ◽  
Positioning Systems ◽  
Control Approach ◽  
Mode Control

The authors introduce a new controller, aimed at industrial domains, that improves the performance and accuracy of positioning systems based on Stewart platforms. More specifically, this paper presents, and validates experimentally, a sliding mode control for precisely positioning a Stewart platform used as a mobile platform in non-destructive inspection (NDI) applications. The NDI application involves exploring the specimen surface of aeronautical coupons at different heights. In order to avoid defocusing and blurred images, the platform must be positioned accurately to keep a uniform distance between the camera and the surface of the specimen. This operation requires the coordinated control of the six electro mechanic actuators (EMAs). The platform trajectory and the EMA lengths can be calculated by means of the forward and inverse kinematics of the Stewart platform. Typically, a proportional integral (PI) control approach is used for this purpose but unfortunately this control scheme is unable to position the platform accurately enough. For this reason, a sliding mode control (SMC) strategy is proposed. The SMC requires: (1) a priori knowledge of the bounds on system uncertainties, and (2) the analysis of the system stability in order to ensure that the strategy executes adequately. The results of this work show a higher performance of the SMC when compared with the PI control strategy: the average absolute error is reduced from 3.45 mm in PI to 0.78 mm in the SMC. Additionally, the duty cycle analysis shows that although PI control demands a smoother actuator response, the power consumption is similar.

scholarly journals Terminal Sliding-Mode Control of Uncertain Robotic Manipulator System with Predefined Convergence Time

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yang Wang ◽  
Mingshu Chen ◽  
Yu Song
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Design Method ◽  
Robotic Manipulator ◽  
Convergence Time ◽  
Terminal Sliding Mode Control ◽  
Tracking Errors ◽  
Terminal Sliding Mode ◽  
Mode Control ◽  
Control Scheme

This paper concentrates on the predefined-time trajectory tracking for an uncertain robotic manipulator system. First, a modified predefined-time control (PTC) algorithm is proposed. Subsequently, with the help of proposed modified PTC algorithm and the nonsingular design method of terminal sliding mode, a novel nonsingular terminal sliding-mode control (NTSMC) scheme is proposed for ensuring the predefined-time convergence of tracking errors. The advantages of the newly proposed control scheme are as follows. (i) Unlike the conventional predefined-time sliding-mode control (SMC) which only guarantees the predefined-time convergence of sliding-mode surface, the proposed scheme can guarantee the predefined-time convergence of tracking errors. (ii) Compared with the conventional PTC algorithm, the proposed modified PTC algorithm can reduce the initial control peaking and enhance the precision of convergence time. The performance and effectiveness of the proposed control scheme are illustrated by comparing with the existing methods.

Fault Tolerance of a Reconfigurable Tilt-Rotor Quadcopter Using Sliding Mode Control

2018 ◽  
Author(s):  
Siddharth Sridhar ◽  
Rumit Kumar ◽  
Kelly Cohen ◽  
Manish Kumar
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Control Technique ◽  
State Variables ◽  
Servo Motor ◽  
Tracking Errors ◽  
Tilt Rotor ◽  
Sliding Surfaces ◽  
Mode Control ◽  
Non Linear

Tilt-rotor quadcopters are a novel class of quadcopters with a servo motor attached on each arm that assist the quadcopter’s rotors to tilt to a desired angle thereby enabling thrust vectoring. Using these additional tilt angles, this type of a quadcopter can be used to achieve desired trajectories with faster maneuvering and can handle external disturbances better than a conventional quadcopter. In this paper, a non-linear controller has been designed using sliding mode technique for the pitch, roll, yaw motions and the servo motor tilt angles of the quadcopter. The dynamic model of the tilt-rotor quadcopter is presented, based on which sliding surfaces were designed to minimize the tracking errors. Using the control inputs derived from these sliding surfaces, the state variables converge to their desired values in finite-time. Further, the non-linear sliding surface coefficients are obtained by stability analysis. The robustness of this proposed sliding mode control technique is shown when a faulty motor scenario is introduced. The quadcopter transforms into a T-copter design upon motor failure thereby abetting the UAV to cope up with the instabilities experienced in yaw, pitch and roll axes and still completing the flight mission. The dynamics of the T-copter design and the derivation of the switching surface coefficients for this reconfigurable system are also presented.

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