Fixed-Time-Convergent Generalized Extended State Observer Based Motor Control Subject to Multiple Disturbances

Cooperative output regulation problem has been studied on the basis of an observer which is capable of estimating the state of the leader system in a distributed fashion. However, in the literature, the convergence rate is at best exponential with infinite settling time. To improve the transient performance of the closed-loop system, a prescribed-time distributed control law is synthesized to solve the cooperative output regulation problem for a class of linear multi-agent systems with external disturbances. Different from existing works, we first design a distributed observer to estimate the state of the dynamic leader in the fixed time which is independent of the initial conditions. The design of such an observer extends the results from a homogeneous multi-agent system to a heterogeneous one. And then a time-varying distributed control law is designed on the basis of the parametric Lyapunov function technique. The efficiency of our design has been validated in the control of the lateral directional dynamics of aircraft systems.

Section: Prescribed-time Cooperative Output Regulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prescribed‐time cooperative output regulation of heterogeneous multi‐agent systems

Dong

Wang

2023

“…Within this framework, researchers have successfully integrated fixed time theory with SMC to achieve better control results for motor servo systems. [16][17][18][19] Reference 20 proposes a global fixed-time non-singular TSM (FTNTSM) that enhances the speed tracking performance of PMSM systems. However, all the aforementioned papers modify the control law to avoid singularities, which makes parameter tuning more difficult and is not conducive to practical applications.…”

Section: Introductionmentioning

confidence: 99%

Fixed‐time dual sliding mode control for linear synchronous motor maglev systems

Lei,

Lan,

et al. 2024

A dual fixed‐time terminal sliding mode control strategy is proposed to address the problems of magnetic coupling, end effects and unknown disturbances in linear synchronous motor maglev systems, which ensures that the system tracking trajectory achieves fixed‐time convergence and high accuracy. First, a fixed‐time integral terminal sliding mode surface is designed to obtain the desired dynamic properties and avoid the singularity problem. Second, based on the dynamic sliding mode theory, a second fixed‐time terminal sliding mode surface is designed to weaken the chattering problem in the controller by replacing the discontinuous switching signal with a continuous switching rule. The proposed controller is theoretically proved to be fixed‐time convergent and the convergence time is independent of the initial conditions by means of the Lyapunov function and the fixed‐time convergence theorem. Finally, simulations and experiments are carried out on a linear maglev experimental platform. Compared with the fixed‐time sliding mode control, the simulation and experimental results show that the proposed strategy improves the tracking accuracy by 37.5%, the convergence speed by 33.3%, and the robustness by 42.1%, which has the advantages of fast convergence speed, strong robustness, and weak chattering.

“…1 In particular, the discontinuous and fast time-varying friction dynamics around the zero velocities can generate the undesirable stick-slip, flat peak and limit cycle. [2][3][4][5][6][7] In theory, the friction can be approximately described by a function in terms of the velocity. Therefore, the online compensation is extremely difficult in the absence of velocity measurement, which is a common situation in practice for cost saving and weight reduction.…”

Section: Introductionmentioning

confidence: 99%

“…To be specific, the friction dynamics is very complicated, and it is affected by many different mechanisms, such as the contact geometry, the surface materials of the bodies, the presence of the lubrication, as well as the displacement and the relative velocity of the bodies 1 . In particular, the discontinuous and fast time‐varying friction dynamics around the zero velocities can generate the undesirable stick‐slip, flat peak and limit cycle 2‐7 . In theory, the friction can be approximately described by a function in terms of the velocity.…”

Section: Introductionmentioning

confidence: 99%

Disturbance observer‐based robust motor control enhanced by adaptive neural network in the absence of velocity measurement

Piao

Tan

Wang³

et al. 2022

Self Cite

High‐precision servo motor control has been a challenging problem due to the multiple disturbances such as the friction, the load variation and the wide/narrow‐band torque disturbances. Particularly, the discontinuous and fast time‐varying friction is very difficult to be compensated, which tends to trigger the undesirable limit cycle. In addition, the friction is a function of the angular velocity, which makes the online compensation extremely hard in the absence of velocity measurement. To make the matter worse, the nonvanishing narrow‐band torque disturbances in some applications often cause residual vibrations if they are not sufficiently rejected. To address these problems, a robust motor control method, which can effectively reject the multiple disturbances without velocity measurement, is proposed in this article. To be specific, an adaptive hybrid model, which includes an adaptive neural network and a sign function, is employed to compensate the discontinuous and fast time‐varying friction dynamics. Furthermore, by incorporating the internal models of the narrow‐band disturbances into the plant, a resonant extended state observer is designed to estimate the remaining lumped disturbance. To derive the high‐order derivatives of the angular position, a fixed‐time‐convergent differentiator is employed. Different from the previous studies, elaborately designed filters are introduced in the adaptive laws. In this way, the possible degradation of transient performance and stability robustness caused by the adaptive control can be effectively avoided. The closed‐loop stability can be rigorously proved by using the Lyapunov theory. Finally, extensive experiments are performed on a servo motor to validate the effectiveness of the proposed method.