Barrier Lyapunov Function Based Output Control and Extended State Observer for a Manipulator with Time-Varying Output Constraints and Uncertainties

2019 ◽  
Author(s):  
Duc Thien Tran ◽  
Hoang Vu Dao ◽  
Huan Liu ◽  
Young Jin Yum ◽  
Kyoung Kwan Ahn
Keyword(s):  
Lyapunov Function ◽  
State Observer ◽  
Extended State Observer ◽  
Time Varying ◽  
Extended State ◽  
Output Control ◽  
Barrier Lyapunov Function ◽  
Output Constraints

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.

Dual extended state observer-based backstepping control of electro-hydraulic servo systems with time-varying output constraints

2019 ◽  
Vol 42 (5) ◽  
pp. 1070-1080
Author(s):  
Guichao Yang
Keyword(s):  
Hydraulic System ◽  
State Observer ◽  
Extended State Observer ◽  
Time Varying ◽  
Extended State ◽  
Servo Systems ◽  
Output Constraints ◽  
Unknown Disturbances ◽  
Hydraulic Servo ◽  
Mismatched Disturbances

In this paper, a novel nonlinear robust controller ensuring time-varying output constraints for the double-rod hydraulic servo systems in the presence of largely unknown matched and mismatched disturbances is proposed. By employing two extended state observers for each channel of the load dynamics and pressure dynamics of the considered hydraulic system, the large matched and mismatched disturbances are successfully compensated. In addition, a time-varying barrier Lyapunov function (BLF) of asymmetric type has been employed to make sure that the position output is never violated. The resulting controller is synthesized using the backstepping procedure. The stability of the whole closed-loop hydraulic system associated with the dual extended state observer (ESO)-based controller is strictly guaranteed. In theory, the proposed control strategy can not only ensure the output satisfy the preset constrained space, but also enhance the output tracking performance when the system faces various largely unknown disturbances. The effectiveness of the proposed controller has also been demonstrated via comparative simulation results.

Tracking Control for Switched Nonlinear Systems Subject to Time-Varying Output Constraints

2012 ◽  
Author(s):  
Ben Niu ◽  
Georgi M. Dimirovski ◽  
Jun Zhao
Keyword(s):  
Nonlinear Systems ◽  
Lyapunov Function ◽  
Tracking Control ◽  
Closed Loop ◽  
Time Varying ◽  
Switched Nonlinear Systems ◽  
Feedback Form ◽  
Barrier Lyapunov Function ◽  
Output Constraints ◽  
Asymptotic Tracking

In this paper, we address the tracking control problem for switched nonlinear systems in strict-feedback form with time-varying output constraints. To prevent the output from violating the time-varying constraints, we employ a Barrier Lyapunov Function, which relies explicitly on time. Based on the simultaneous domination assumption, we design a controller for the switched system, which guarantees that asymptotic tracking is achieved without transgression of the constraints and all closed-loop signals remain bounded under arbitrary switchings. The effectiveness of the proposed results is illustrated using a numerical example.

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