Research on variable mass control of series manipulator based on linear active disturbance rejection control

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.

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.

This paper investigates the design problem of the attitude controller for air-breathing supersonic vehicle subject to uncertainties and disturbances. Firstly, the longitudinal model is established for the attitude controller design which is devised as a strict feedback formulation, and a transformed tracking error is derived with the prescribed performance control technique such that it can limit the tracking error to a predefined region. Then, a novel linear active disturbance rejection control scheme is proposed for the attitude system to enhance the steady-state and transient-state performances by incorporating the transformed tracking error. On the basis of the Lyapunov stability theorem, the convergence and stability characteristics are both rigorously proved for the closed-loop system. Finally, extensive contrast simulations are conducted to demonstrate the effectiveness, robustness, and advantage of the proposed control strategy.

The control strategy research of the time-delay system is a focused issue in the control field. In order to furthermore improve the performance of the first-order time-delay inertial system, firstly, a new Smith predictor structure is proposed, which solves the constraint that the conventional Smith predictor needs to match the actual object model. Secondly, the performance and parameter function of the new Smith predictor are discussed in theory to provide the basis for parameter tuning. Finally, a new Smith predictor combined with linear active disturbance rejection control (LADRC) is proposed to solve the problem that the two input signals of the linear extended state observer (LESO) are not synchronized on the time scale, and the stability of the new Smith + LADRC time-delay control system is proved theoretically for known and unknown controlled complex objects. Simulation analysis is conducted to verify the robustness of the proposed strategy under the condition of the different parameters. The results indicate that the proposed strategy has better performance than the conventional method in response speed, overshoot, adjustment time, and stability.

For joint space control of the pneumatic translational parallel manipulator, in order to improve the tracking accuracy of the space trajectory, not only the tracking error of a single driving limb needs to be reduced, but also the coupling of driving limbs and the motion coordination need to be considered. A linear active disturbance rejection control with consideration of position error compensation is proposed for pneumatic translational parallel manipulator. A linear active disturbance rejection controller is used for single driving limb to overcome the compressibility of the gas, the time-varying load and the friction. In addition, position error compensation is used to solve the problem of the motion coordination, further reducing tracking error of space trajectory. The effectiveness of the control strategy is verified by experiment.

Remotely operated vehicles (ROVs) face challenges in achieving optimal trajectory tracking performance during underwater movement due to external disturbances and parameter uncertainties. To address this issue, this paper proposes a position and attitude control strategy for underwater robots based on a reinforcement learning active disturbance rejection controller. The linear active disturbance rejection controller has achieved satisfactory results in the field of underwater robot control. However, fixed-parameter controllers cannot achieve optimal control performance for the controlled object. Therefore, further exploration of the adaptive capability of control parameters based on the linear active disturbance rejection controller was conducted. The deep deterministic policy gradient (DDPG) algorithm was used to optimize the linear extended state observer (LESO). This strategy employs deep neural networks to adjust the LESO parameters online based on measured states, allowing for more accurate estimation of model uncertainties and environmental disturbances, and compensating the total disturbance into the control input online, resulting in better disturbance estimation and control performance. Simulation results show that the proposed control scheme, compared to PID and fixed parameter LADRC, as well as the double closed-loop sliding mode control method based on nonlinear observers (NESO-DSMC), significantly improves the disturbance estimation accuracy of the linear active disturbance rejection controller, leading to higher control precision and stronger robustness, thus demonstrating the effectiveness of the proposed control strategy.

Hydrogen energy storage systems are becoming increasingly accepted owing to their environmental friendliness. The efficiency and performance of these systems largely depend on the attributes of their power electronic interface systems. Among the promising solutions is a multiport-isolated DC-DC converter with characteristics of reduced component count, fewer conversion stages, and galvanic isolation. However, this system presents a challenge due to its inherent cross-coupling effect, complicating precise control. To address this, linear active disturbance rejection control (LADRC) is a viable option, leveraging dynamic/disturbance properties observed by linear extended state observers. LADRC serves as a decoupling controller, mitigating the cross-coupling effect. However, LADRC has several gains, and selecting them can be a difficult task, often requiring manual tuning. To streamline this process, this paper proposes utilising particle swarm optimisation to determine the optimum gains of LADRC. By employing this approach, the implementation of LADRC is facilitated with reduced design efforts while ensuring effective decoupling control within the system. Simulations are conducted to validate the performance of the optimised gain LADRC.

This paper takes the single-phase off-grid inverter as the research object, proposes a linear active disturbance rejection control (LADRC) strategy, and conducts discretization processing. Firstly, a mathematical model of the single-phase off-grid inverter is established, and a state-space model is constructed. Then, according to the state-space model, a continuous-domain LADRC controller is designed. Subsequently, the current Euler method and the current zero-order hold(ZOH) method are respectively employed to discretize the controller. Finally, through Matlab/Simulink simulation, the performances of the two discretization methods in terms of total harmonic distortion(THD), output voltage error, etc., under different operating conditions are compared, which provides a reference for practical engineering applications.

In this paper, linear active disturbance rejection control (LADRC) is investigated for the load frequency control (LFC) systems with wind turbine. The wind power is considered as a stochastic load to the power grid. To compensate the stochastic disturbance with LADRC, we adopt a two-stage design method. First an LQG controller is designed to handle the stochastic nature of the load, then the intrinsic link between LQG and LADRC is analyzed and the designed LQG controller is converted to a conventional LADRC so that the LADRC maintains the same property of rejecting stochastic disturbance with the LQG controller. Simulation results show that the designed LADRC with the proposed method can damp the stochastic load disturbance very well.

LLC resonant converter, which is widely used in the charging of new energy vehicles, can achieve zero-voltage switching (ZVS) of the primary side MOSFET and zero-current switching (ZCS) of the secondary side rectifying diode. They also have the advantages of high efficiency and high-power density. The output voltage is still affected by input voltage fluctuation, reference voltage change, load mutation and other factors. The charging mode of automobile batteries with different materials is also different. In order to stabilize the output voltage and realize automatic switching of constant voltage and current, this paper proposes a double closed-loop linear active disturbance rejection control (LADRC) scheme. Firstly, the transfer functions of the system are obtained by extended description function (EDF) method and simulation method respectively. The transfer functions of the two methods are compared and analysed. Finally, the LADRC controller and PI controller are simulated and compared, and the dynamic performance of the control system is evaluated by ITAE index. The experimental results show that the output voltage of LADRC control is more stable.

A position-disturbing force servo loading system consisting of two opposing hydraulic cylinders, a hydraulic loading cylinder and a bearing hydraulic cylinder, is the most common loading form. Aiming at the problem that the bearing hydraulic cylinder would bring superfluous force to the loading system, a solution to the ADRC controller is proposed. Based on the analysis of the mathematical model of the position disturbance type electro-hydraulic servo force loading mechanism, a first-order linear active disturbance rejection controller is designed according to the relative order of the system. The total disturbance of the system, including the superfluous force, is estimated by the extended state observer, and the linear error feedback control law is used for real-time compensation. The simulation results show that compared with the PID controller, the ADRC controller has better tracking accuracy, higher response speed and stronger robustness, and has the stronger anti-interference ability when the bearing system moves.

The direct drive of the permanent magnet linear synchronous motor (PMLSM) requires excellent disturbance rejection capability to achieve precise position control. This article proposes an improved adaptive linear active disturbance rejection control (IALADRC) to improve trajectory tracking and disturbance rejection capability. First, we explain the difference between proportional–integral–derivative (PID) control and LADRC in terms of trajectory tracking and disturbance rejection. Unlike PID, which uses the integral controller to reject disturbances, LADRC uses the extended state observer (ESO) to decouple reference tracking and disturbance rejection. This simplifies the PMLSM control system to a second-order system, which in turn inspired the proposal of the improved LADRC (ILADRC). ILADRC reconstructs the disturbance from the position error using the inverse closed-loop model and injects it into the control output, resulting in better control performance. Due to the complex disturbance existing in the motion process of PMLSM, an improved adaptive ESO (AESO) is proposed to strike a balance between disturbance estimation and noise reduction. The ILADRC and the improved AESO are combined to form the IALADRC. Comparative experiments show that the IALADRC has excellent disturbance rejection capability and significantly improves the position control accuracy of the PMLSM system.

New fractional-order LADRC scheme based on a novel filtered-Bode’s ideal transfer function for integer-order systems

In order to improve the grid-connected stability of wind power grid-connected inverter, solve the harmonic and resonance problems encountered at the grid-connected interface of inverter when the load jumps. An improved linear active disturbance rejection control strategy combined with active damping (ILADRC-AD) is designed. Firstly, the mathematical model of inductance-capacitance-inductance (LCL) inverter is established, and the principle of traditional third order active disturbance rejection controller is analyzed. Based on the idea of lead correction, an improved LADRC is designed by series lead correction links on the total disturbance channel of the linear extended state observer (LESO). Capacitive current feedback active damping is introduced in combination with improved LADRC to generate an ILADRC-AD control strategy. The stability and robustness of the system are effectively improved. Finally, the frequency characteristics of the ILADRC-AD inverter system are analyzed by frequency domain analysis method, and the MATLAB simulation comparison of improved control and traditional PI and LADRC the grid current waveform. The results show that the improved control not only has more stable grid-connected current, but also has fast dynamic response and strong harmonic suppression when the load fluctuates.

There exists a steady-state error in the closed-loop system output with some conventional linear active rejection control approaches when the pitch channel control variable of the near space vehicle is the angle of attack. In this study, a cascaded linear active disturbance rejection control approach based on the cascaded control idea is proposed. Both the inner-loop controller and the outer-loop controller are designed by the linear active disturbance rejection control method. The inner-loop is built by angular rate feedback to improve dynamic performance of the closed-loop system, and the outer-loop is built by angle of attack feedback to remove the undesired steady-state error. The approach is employed to a hypersonic near space vehicle autopilot. The numerical simulations show that the proposed approach preserves the performances on time domain and frequency domain as good as those of the conventional active disturbance rejection control approaches, and it has the better performances on disturbance rejection and angle of attack command tracking accuracy than those of some previous active disturbance rejection control approaches.