scholarly journals Output Feedback Control via Linear Extended State Observer for an Uncertain Manipulator with Output Constraints and Input Dead-Zone

Electronics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1355 ◽  
Author(s):  
Duc Thien Tran ◽  
Hoang Vu Dao ◽  
Truong Quang Dinh ◽  
Kyoung Kwan Ahn
Keyword(s):  
Lyapunov Function ◽  
Output Feedback ◽  
Dead Zone ◽  
External Disturbance ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Barrier Lyapunov Function ◽  
Output Constraints ◽  
Linear Extended State Observer

This paper proposes an output feedback controller with a linear extended state observer (LESO) for an n-degree-of-freedom (n-DOF) manipulator under the presence of external disturbance, an input dead-zone, and time-varying output constraints. First, these issues are derived in mathematical equations accompanying an n-DOF manipulator. The proposed control is designed based on the backstepping technique with the barrier Lyapunov function (BLF) and a LESO. The LESO is used for estimating both the unmeasured states and the lumped uncertainties including the unknown frictions, external disturbances, and input dead-zone, in order to enhance the accuracy of the robotic manipulator. Additionally, the BLF helps to avoid violation of the output constraints. The stability and the output constraint satisfaction of the controlled manipulator are theoretically analyzed and proven by the Lyapunov theorem with a barrier Lyapunov function. Some comparative simulations are carried out on a 3-DOF planar manipulator. The simulation results prove the significant performance improvement of the proposed control over the previous methods.

scholarly journals Sliding Mode Control Based on High-Order Linear Extended State Observer for Near Space Vehicle

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Ouxun Li ◽  
Ju Jiang ◽  
Li Deng ◽  
Shutong Huang
Keyword(s):  
Sliding Mode ◽  
External Disturbance ◽  
State Observer ◽  
High Order ◽  
Extended State Observer ◽  
Sliding Mode Controller ◽  
Extended State ◽  
Order Linear ◽  
Near Space ◽  
Linear Extended State Observer

Aiming at the uncertainty and external disturbance sensitivity of the near space vehicles (NSV), a novel sliding mode controller based on the high-order linear extended state observer (LESO) is designed in this paper. In the proposed sliding mode controller, the double power reaching law is adopted to enhance the state convergence rate, and the high-order LESO is designed to improve the antidisturbance ability. Moreover, the appropriate observer bandwidth and extended order are selected to further reduce or even eliminate the disturbance by analyzing their influences on the observer performance. Finally, the simulation demonstrations are given for the NSV control system with uncertain parameters and external disturbances. The theoretical analyses and simulation results consistently indicate that the proposed high-order LESO with carefully selected extended order and observer bandwidth has better performance than the traditional ones for the nonlinear NSV system with parametric uncertainty and external disturbance.

scholarly journals Robust Sliding Mode Control for a 2-DOF Lower Limb Exoskeleton Base on Linear Extended State Observer

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Zhenlei CHEN ◽  
Qing GUO ◽  
Yao YAN ◽  
Dan JIANG
Keyword(s):  
Sliding Mode Control ◽  
Lower Limb ◽  
Sliding Mode ◽  
External Disturbance ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Lower Limb Exoskeleton ◽  
Mode Control ◽  
Linear Extended State Observer

For the 2- Degree of Freedom (DOF) lower limb exoskeleton, to ensure the system robustness and dynamic performance, a linear-extended-state-observer-based (LESO) robust sliding mode control is proposed to not only reduce the influence of parametric uncertainties, unmodeled dynamics, and external disturbance but also estimate the unmeasurable real-time joint angular velocity directly. Then, via Lyapunov technology, the stability of the corresponding LESO and controller is proven. The appropriate and reasonable simulation was carried out to verify the effectiveness of the proposed LESO and exoskeleton controller.

scholarly journals PD-Based Optimal ADRC with Improved Linear Extended State Observer

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 888
Author(s):  
Zhen Zhang ◽  
Jian Cheng ◽  
Yinan Guo
Keyword(s):  
Disturbance Rejection ◽  
Dead Zone ◽  
State Observer ◽  
Extended State Observer ◽  
Control Law ◽  
Extended State ◽  
Pd Control ◽  
Active Disturbance Rejection ◽  
Linear Extended State Observer ◽  
The Dead

Taking dead-zone nonlinearlity and external disturbances into account, an active disturbance rejection optimal controller based on a proportional-derivative (PD) control law is proposed by connecting the proportional-integral-derivative (PID) control, the active disturbance rejection control (ADRC) and particle swarm optimization (PSO), with the purpose of providing an efficient and practical technology, and improving the dynamic and steady-state control performances. Firstly, in order to eliminate the negative effects of the dead-zone, a class of 2-order typical single-input single-out system model is established after compensating the dead-zone. Following that, PD control law is introduced to replace the state error feedback control law in ADRC to simplify the control design. By analyzing the characteristics of the traditional linear extended state observer, an improved linear extended state observer is designed, with the purpose of improving the estimation performance of disturbances. Moreover, employing PSO with a designed objective function to optimize parameters of controller to improve control performance. Finally, ten comparative experiments are carried out to verify the effectiveness and superiority of the proposed controller.

Extended state observer–based output feedback control for spacecraft pose tracking with control input saturation

2021 ◽  
pp. 095441002110177
Author(s):  
Kejie Gong ◽  
Ying Liao ◽  
Yafei Mei
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Finite Time ◽  
Output Feedback Control ◽  
State Observer ◽  
Extended State Observer ◽  
Control Input ◽  
Extended State ◽  
Pose Tracking ◽  
Control Scheme

This article proposed an extended state observer (ESO)–based output feedback control scheme for rigid spacecraft pose tracking without velocity feedback, which accounts for inertial uncertainties, external disturbances, and control input constraints. In this research, the 6-DOF tracking error dynamics is described by the exponential coordinates on SE(3). A novel continuous finite-time ESO is proposed to estimate the velocity information and the compound disturbance, and the estimations are utilized in the control law design. The ESO ensures a finite-time uniform ultimately bounded stability of the observation states, which is proved utilizing the homogeneity method. A non-singular finite-time terminal sliding mode controller based on super-twisting technology is proposed, which would drive spacecraft tracking the desired states. The other two observer-based controllers are also proposed for comparison. The superiorities of the proposed control scheme are demonstrated by theory analyses and numerical simulations.

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