A dual-loop robust controller for DC electro-mechanical servo system

Author(s):  
Tianpeng He ◽  
Shu Li ◽  
Xiaodong Liu

In order to further improve the tracking performances of the conventional disturbance observer (DOB)-based control schemes, a dual-loop robust control scheme is proposed for DC electro-mechanical servo system. The outer-loop sliding mode controller (SMC) is designed in order to deal with the impacts from the remainder equivalent disturbances, which is due to the inadequate estimation of the inner-loop DOB. Meanwhile, the existence of DOB can reduce the switching gain of SMC law, which can suppress the high-frequency chattering of control input to a certain extent. Moreover, an approximate differential method is employed in order to reliably acquire the differential information in a noisy environment. From the experiment results on a DC motor servo system, it is presented that the proposed dual-loop control scheme can effectively improve the tracking performances with respect to higher tracking accuracy and stronger system robustness against external disturbances and parameter perturbations, compared with the traditional DOB+PD control scheme.

Author(s):  
Afef Hfaiedh ◽  
Ahmed Chemori ◽  
Afef Abdelkrim

In this paper, the control problem of a class I of underactuated mechanical systems (UMSs) is addressed. The considered class includes nonlinear UMSs with two degrees of freedom and one control input. Firstly, we propose the design of a robust integral of the sign of the error (RISE) control law, adequate for this special class. Based on a change of coordinates, the dynamics is transformed into a strict-feedback (SF) form. A Lyapunov-based technique is then employed to prove the asymptotic stability of the resulting closed-loop system. Numerical simulation results show the robustness and performance of the original RISE toward parametric uncertainties and disturbance rejection. A comparative study with a conventional sliding mode control reveals a significant robustness improvement with the proposed original RISE controller. However, in real-time experiments, the amplification of the measurement noise is a major problem. It has an impact on the behaviour of the motor and reduces the performance of the system. To deal with this issue, we propose to estimate the velocity using the robust Levant differentiator instead of the numerical derivative. Real-time experiments were performed on the testbed of the inertia wheel inverted pendulum to demonstrate the relevance of the proposed observer-based RISE control scheme. The obtained real-time experimental results and the obtained evaluation indices show clearly a better performance of the proposed observer-based RISE approach compared to the sliding mode and the original RISE controllers.


Author(s):  
Nasim Ullah ◽  
Irfan Sami ◽  
Wang Shaoping ◽  
Hamid Mukhtar ◽  
Xingjian Wang ◽  
...  

This article proposes a computationally efficient adaptive robust control scheme for a quad-rotor with cable-suspended payloads. Motion of payload introduces unknown disturbances that affect the performance of the quad-rotor controlled with conventional schemes, thus novel adaptive robust controllers with both integer- and fractional-order dynamics are proposed for the trajectory tracking of quad-rotor with cable-suspended payload. The disturbances acting on quad-rotor due to the payload motion are estimated by utilizing adaptive laws derived from integer- and fractional-order Lyapunov functions. The stability of the proposed control systems is guaranteed using integer- and fractional-order Lyapunov theorems. Overall, three variants of the control schemes, namely adaptive fractional-order sliding mode (AFSMC), adaptive sliding mode (ASMC), and classical Sliding mode controllers (SMC)s) are tested using processor in the loop experiments, and based on the two performance indicators, namely robustness and computational resource utilization, the best control scheme is evaluated. From the results presented, it is verified that ASMC scheme exhibits comparable robustness as of SMC and AFSMC, while it utilizes less sources as compared to AFSMC.


2021 ◽  
Author(s):  
Vangjel Pano

Developed in this thesis is a new control law focusing on the improvement of contour tracking of robotic manipulators. The new control scheme is a hybrid controller based on position domain control (PDC) and position synchronization control (PSC). On PDC, the system’s dynamics are transformed from time domain to position domain via a one-to-one mapping and the position of the master axis motion is used as reference instead of time. The elimination of the reference motion from the control input improves contouring performance relative to time domain controllers. Conversely, PSC seeks to reduce the error of the systems by diminishing the synchronization error between each agent of the system. The new control law utilizes the aforementioned techniques to maximize the contour performance. The Lyapunov method was used to prove the proposed controller’s stability. The new control law was compared to existing control schemes via simulations of linear and nonlinear contours, and was shown to provide good tracking and contouring performances.


1985 ◽  
Vol 107 (3) ◽  
pp. 200-206 ◽  
Author(s):  
Y. Sakawa ◽  
A. Nakazumi

In this paper we first derive a dynamical model for the control of a rotary crane, which makes three kinds of motion (rotation, load hoisting, and boom hoisting) simultaneously. The goal is to transfer a load to a desired place in such a way that at the end of transfer the swing of the load decays as quickly as possible. We first apply an open-loop control input to the system such that the state of the system can be transferred to a neighborhood of the equilibrium state. Then we apply a feedback control signal so that the state of the system approaches the equilibrium state as quickly as possible. The results of computer simulation prove that the open-loop plus feedback control scheme works well.


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Changfan Zhang ◽  
Qian Zhang ◽  
Jing He ◽  
Jianhua Liu ◽  
Xingxing Yang ◽  
...  

In the coordinated control of multiple motors for heavy-haul locomotives, the input value for a motor often exceeds its maximum allowable input value, resulting in the saturation problem. A traction total-amount coordinated tracking control (TACTC) strategy is proposed to address the input saturation of heavy-haul locomotives driven by multiple motors. This strategy reduces control input and suppresses input saturation. First, a multimotor traction model with uncertain parameter perturbations and external disturbances was established. Next, a sliding-mode disturbance observer (SMDO) was designed to reduce the sliding-mode switching gain, thereby decreasing the control input. An auxiliary anti-windup (AW) system was used to weaken the effect of input saturation on tracking performance. Then, the observed value and auxiliary state were fed back to the sliding-mode controller to design a TACTC protocol and ensure that the total amount of traction torque follows the desired traction characteristic curve. Finally, the Matlab/Simulink simulation and RT-Lab semiphysical experiment results show that the proposed strategy can effectively suppress the input saturation problem of multimotor coordinated control.


2016 ◽  
Vol 39 (3) ◽  
pp. 371-383 ◽  
Author(s):  
Alireza Modirrousta ◽  
Mahdi Khodabandeh

This paper proposes two different adaptive robust sliding mode controllers for attitude, altitude and position control of a quadrotor. Firstly, it proposes a backstepping non-singular terminal sliding mode control with an adaptive algorithm that is applied to the quadrotor for free chattering, finite time convergence and robust aims. In this control scheme instead of regular control input, the derivative of the control input is achieved from a non-singular terminal second-layer sliding surface. An adaptive tuning method is utilized to deal with the external disturbances whose upper bounds are not required to be known in advance in the inner loop. Secondly, a nonlinear disturbance observer based on the integral sliding mode with adaptive gains is proposed for position control, which is known as the outer loop. Stability and robustness of the proposed controller are proved by using the classical Lyapunov criterion. The simulation results demonstrate the validation of the proposed control scheme.


2008 ◽  
Vol 594 ◽  
pp. 401-406 ◽  
Author(s):  
Jin Wei Liang ◽  
Hung Yi Chen ◽  
Shy Yaw Chiang

The fuzzy sliding-mode control strategy is used to tackle tracking problem of a piezo-actuated stage in this paper. The piezo-actuated system is composed of the piezoelectric actuator and a positioning mechanism. Due to hysteretic nonlinearity of the piezoelectric actuator, the tracking accuracy of the system is limited. To compensate for this nonlinearity, a feedback fuzzy sliding-mode control augmented with a predictor-based feedforward compensator is proposed. The controller, denoted as the feedforward-feedback fuzzy sliding-mode controller (FF-FSMC), can be applied to eliminate tracking error caused by the hysteretic characteristics. Experimental results on different types of reference inputs indicate that the proposed control schemes may suppress the tracking error of the piezo-actuated system effectively.


Complexity ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-19
Author(s):  
Chen Zhang ◽  
Wen Qin ◽  
Ming-Can Fan ◽  
Ting Wang ◽  
Mou-Quan Shen

This paper proposes an adaptive formation tracking control algorithm optimized by Q-learning scheme for multiple mobile robots. In order to handle the model uncertainties and external disturbances, a desired linear extended state observer is designed to develop an adaptive formation tracking control strategy. Then an adaptive method of sliding mode control parameters optimized by Q-learning scheme is employed, which can avoid the complex parameter tuning process. Furthermore, the stability of the closed-loop control system is rigorously proved by means of matrix properties of graph theory and Lyapunov theory, and the formation tracking errors can be guaranteed to be uniformly ultimately bounded. Finally, simulations are presented to show the proposed algorithm has the advantages of faster convergence rate, higher tracking accuracy, and better steady-state performance.


Author(s):  
Nasim Ullah ◽  
Alsharef Mohammad

The coupled tank system is the most widely used sub-component in chemical process industries. Fluid mixing is a major step in chemical processes that alters the material properties and cost. Fluid flow and its level regulation between several tanks are important control problems. As the first step, this paper addresses the level regulation problem using classical integer order proportional, derivative, integral (PID), fractional order PID controllers. As a second step, model-based robust fractional order controllers are derived using sliding mode approach in order to achieve the desired response, parameters of the proposed controllers are tuned using genetic algorithm. Finally, system performance under all variants of control schemes has been tested using numerical simulations.


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