Research on Position-Tracking Control Method for Fatigue Test Bed of Absorber Based on SCHO and Fuzzy Adaptive LADRC

Linear motors are widely used in semiconductor packaging equipment to achieve high-speed and high-acceleration linear motion as well as high positioning accuracy. The linear motor XY motion platform is an essential component of semiconductor packaging equipment and consequently, the improvement of its motion performance is of great significance to the packaging industry. The active disturbance rejection controller (ADRC) is the controller which not only inherits the advantages of traditional PID controller which decreases tracking errors based on tracking errors, but also can make system realize high response speed and small overshoot at the same time. The linear active disturbance rejection controller (LADRC) is a linear simplified ADRC with the characteristics of easier parameter tunning. In this paper, LADRC is proposed to be used in the linear motor XY motion platform servo system. System dynamics and disturbances are observed by the linear extended state observer (LESO) and compensated to improve interference rejection capability and stability of the servo system. Besides, the feedforward controller (FFC) is adopted to improve the response speed of the XY platform. A simulation model of the linear motor XY motion platform control system is established to verify the validity of LADRC. Disturbances are applied to the PID, LADRC and LADRC with FFC models respectively. Motion performances under these three situations are compared. The results show that compared with the PID control, linear active disturbance rejection control combined with feedforward compensation can improve the tracking performance and anti-interference ability of the system.

The high-precision motion control of the hydraulic position servo system (HPSS) is facing enormous challenges, because of the problems of parametric uncertainties, flow nonlinearity of servo valve, and unknown external disturbances in a hydraulic system. To address these problems in the framework of linear active disturbance rejection control (LADRC), the traditional third-order model of HPSS is reconstructed into two parts: a single integrator and generalized disturbances. The rationality of the model is demonstrated by the time domain and frequency domain. Then a first-order LADRC can be applied successfully. Meanwhile, a model-auxiliary linear extended state observer (MLESO) is established when the load pressure is measurable. Simulation and calculation show that the MLESO works only under heavy load applications. Co-simulations are carried out to illustrate the effectiveness of the proposed method.

To improve the robustness and the anti-disturbance of control system, regulate its stiffness, a scheme concluding linear active disturbance rejection controllers for pneumatic servo system is proposed. Two linear active disturbance rejection controllers are designed respectively to track the motion and pressure reference. The design of a linear active disturbance rejection controller is independent of precisely mathematical model of the system. The extended state observer can track successfully the states and extended state of the system, and it is possible to realize the states feedback and handle the model uncertainty and compensate external disturbance. The simulation results show that pneumatic servo system based on linear active disturbance rejection controllers is robust against modeling uncertainty and external disturbances. The dynamic performance of the system using linear active disturbance rejection controllers also can be improved as well.

PurposeThe purpose of this paper is to design a third-order linear active disturbance rejection controller (LADRC) to improve the response characteristics and robustness of the electrohydraulic servo system.Design/methodology/approachThe LADRC was designed by replacing the nonlinear functions in each part of ADRC with linear functions or linear combinations, and the parameters of each part of the LADRC were connected with their bandwidth through the pole configuration method to reduce the required tuning parameters, and used an improved grey wolf optimizer to tune the LADRC parameters.FindingsThe anti-interference control simulation and experiment on the LADRC, ADRC and proportion integration differentiation (PID) were carried out to test the robustness, anti-interference ability and superiority of the designed LADRC. The simulation and experiment results showed that the LADRC control and anti-interference control had excellent performance, and because of its simple structure and fewer parameters, LADRC was easier to implement and had a better control effect and anti-interference.Originality/valueFor the problems of parameter perturbation, unknown interference and inaccurate model in the electrohydraulic position servo system, the designed third-order LADRC has good tracking accuracy and anti-interference, has few parameters and is conducive to promotion.

An adaptive linear active disturbance rejection control method for HVDC transmission system

A new robust decentralized controller based on a modified linear active disturbance rejection control structure is proposed in this article. In this work, the proposed controller is designed in a two-degree-of-freedom internal model control framework, to overcome the limitations of extended state observer in active disturbance rejection control. In the proposed controller, tuning parameters, that is, observer bandwidth and controller bandwidth are the inverse of the two-time constants, that is, set-point filter and disturbance rejection filter of internal model control (IMC). Moreover, to show the efficacy of the proposed controller, it has been compared with the linear active disturbance rejection controller (ADRC). Furthermore, to exhibit the superiority, an experimentation is conducted on a coupled tank liquid-level multivariable system. From the obtained simulation and experimental results, it is envisaged that the proposed modified linear active decentralized disturbance rejection controller exhibits superior control performance to maintain a precise desired liquid level as compared to the linear ADRC.

Aiming at the problem of anti-swing and positioning of underactuated crane, this paper proposes a control strategy of underactuated bridge crane based on Linear Active Disturbance Rejection Control and controller parameter optimization method. Distinguished from other conventional control strategies of bridge crane, this method does not require any approximate decoupling or linearization of the crane model and allows the model to have some certain uncertainty, friction and air resistance of the system are also considered. At the same time, for the parameter tuning problem of the sensors, the bird swarm optimization algorithm is applied to optimize the parameters. And the excellent control performance of this method has been proved by simulation.

This paper investigates the stability and performance of the linear active disturbance rejection control (LADRC)–based system with uncertainties and external disturbance via transfer functions and a frequency-domain view. The performance of LADRC is compared with the state-observer-based state feedback control (SOSFC) and state feedback control (SFC). First, the transfer functions and the error transfer functions for LADRC, SOSFC, and SFC are studied using the state-space method. It is proven that the LADRC-, SOSFC-, and SFC-based closed-loop systems have the same transfer function from the reference input to the output and achieve the same control effects for the nominal system. Then, it is proven for the first time that the LADRC has a better anti-interference ability than the SOSFC and SFC. Besides, the asymptotic stability condition of LADRC-based closed-loop system considering large parameter perturbations is given first. Moreover, the sensitivity analysis of the closed-loop system is carried out. The results show that the LADRC has stronger robustness under parameter perturbations. According to the results, we conclude that the LADRC is of great disturbance rejection ability and strong robustness.

The lever-type electric erection system is a novel kind of erection system and the experimental platform in this paper operates with varying loads and low-resolution encoder. For high accuracy trajectory tracking, linear active disturbance rejection control (LADRC) is introduced. An approximate model, consisting of the servo system configured at velocity control mode and the lever-type erection mechanism, is built by means of system identification and curve fitting. Reduced-order LADRC based on the further simplified model is proposed to improve tracking accuracy and robustness. As comparisons, traditional LADRC and PID with high-gain tracking differentiator (HGTD) are designed. Simulation and experimental results indicate that reduced-order LADRC can realize higher trajectory tracking accuracy with low-resolution encoder and has better robustness to variation in erection loads, compared with traditional LADRC and PID with HGTD.

Linear active disturbance rejection control (LADRC) takes the controlled plant as a cascaded integral model and treats all other plant information and external disturbances as a generalized disturbance, and uses an linear extended state observer (ESO) to estimate the generalized disturbance and incorporates it in a linear state feedback control law to reject it quickly. This ESO-based LADRC controller is a fixed-structure controller as long as the (relative) order of the controlled system is specified. This article shows that any linear finite-dimensional controller can be implemented via the LADRC structure; thus, it is a general-purposed control structure in that it can be applied to any control system where linear control is sufficient. Case study shows that the implementation not only retains the disturbance rejection performance of the original linear controller but also improves its tracking performance due to the two-freedom-of-degree property of LADRC.

Path following control for towing system of cylindrical drilling platform in presence of disturbances and uncertainties

In this paper, a fuzzy adaptive linear active disturbance rejection control (Fuzzy-LADRC) is proposed for strong coupling and nonlinear quadrotor unmanned aerial vehicle (UAV). At present, UAV conveys new opportunities in the industry, such as power line inspection, petroleum conduit patrolling, and defects detection for the wind turbine, because of its advantages in flexibility, high efficiency, and economy. Usually, the scene of the UAV mission has a high risk, and there are internal sensor noise and unknown external disturbance. Thus, the attitude stability and anti-interference ability of UAV are especially essential. To solve the strong coupling problem of UAV, the dynamics model of UAV is established via the Newton-Euler method, and the coupling part of dynamics is modeled as an internal disturbance. According to the function of linear active disturbance rejection control (LADRC) parameters, a Fuzzy-LADRC is proposed to improve the dynamic performance of the system. The proposed control method makes full use of the adaptive ability of the fuzzy controller and the anti-interference ability of LADRC to the nonlinear and strong coupling systems. As we know, this is the first time that Fuzzy-LADRC has been used in UAV control. In the simulation, the performance indicators of four controllers, including Fuzzy-LADRC, LADRC, PID, and Fuzzy-PID are compared and analyzed. The results indicate that the average response speed of Fuzzy-LADRC is 12.65% faster than LADRC, and it is 29.25% faster than PID. The average overshoot of Fuzzy-LADRC is 17% less than LADRC and 77.75% less than PID. The proposed control method can significantly improve the response speed and anti-interference ability of UAV.

The principle and structure of linear active disturbance rejection controller(LADRC) are analyzed, and the algorithm of the controller is clarified and the parameter setting process is simplified. Completing the creation and packaging of functional modules of linear active disturbance rejection controller by Simulink modeling idea and creating a module library of linear active disturbance rejection controller. The validity of linear active disturbance rejection controller and the effectiveness of the modeling method are described by linear active disturbance rejection control simulation of a second—order nonlinear time—varying object.

It is well known that proportional-integral-derivative (PID) controllers are dominant in industrial scenarios. PID with high-order derivative or integral terms named generalized PID is superior to the PID. However, there is little literature investigating how to tune the parameters of the generalized PID to enhance the disturbance rejection ability. Toward that end, this article illustrates that the cascade controllers based on the first-order linear active disturbance rejection controllers (LADRCs) (cascade LADRCs) and high-order LADRCs can be interpreted as the generalized PID with low-pass filters for speed servo systems and position servo systems, which in turn is an alternative method to realize the generalized PID. Moreover, the differences between the high-order LADRC and cascade LADRCs are the generalized integral terms, which can be quantified by integral time multiplied absolute error. The proposed LADRC controllers are verified and compared with the current controllers by simulations in MATLAB/Simulink. Finally, one experimental example of the LADRC controllers is implemented on the position servo dc motor system platform.

A grid-connected inverter’s stability is easily influenced by the system’s internal and external characteristics, especially when the grid-connected inverter is connected to the grid by an LCL filter, which complicates the system design and operating conditions. To handle the problem of disturbance in the high-order grid-connected system of the inverter, a linear active disturbance rejection control (LADRC) strategy based on LCCL (which divides the capacitor of the LCL filter into two halves in a specified proportion) is proposed in this paper. First, the system is reduced from third order to first order by using the split capacitor control method, which solves the difficulties of complicated LCL grid-connected inverter controller design and easy resonance. Meanwhile, the internal and external disturbances of the inverter system are treated as generalized disturbances. Then, the LADRC control is used to adjust the closed-loop system’s parameters, which enhances the quality of the grid current and the system’s stability. Finally, the impacts of PI and LADRC control on the power mutation and voltage drop of an LCCL grid-connected inverter are compared by the experiments. The experimental results show the effectiveness of the proposed LADRC control strategy.