scholarly journals Nonlinear Extended State Observer Based on Output Feedback Control for a Manipulator With Time-Varying Output Constraints and External Disturbance

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 156860-156870 ◽  
Author(s):  
Duc Thien Tran ◽  
Maolin Jin ◽  
Kyoung Kwan Ahn
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
External Disturbance ◽  
Output Feedback Control ◽  
State Observer ◽  
Extended State Observer ◽  
Time Varying ◽  
Extended State ◽  
Output Constraints ◽  
Nonlinear Extended State Observer

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.

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.

On the design of extended state observer-based robust finite controller: For underactuated robotic system with multiple sources of uncertainties

2020 ◽  
pp. 014233122096611
Author(s):  
Hui Li ◽  
Ruiqin Li ◽  
Jianwei Zhang
Keyword(s):  
Control Method ◽  
External Disturbance ◽  
Control Process ◽  
Output Feedback Control ◽  
State Observer ◽  
Robotic System ◽  
Extended State Observer ◽  
Extended State ◽  
Multiple Sources ◽  
Parameter Uncertainties

Controlling an underactuated robot is always an important research and engineering issue, especially when the robot is suffering from multiple sources of uncertainties, such as unmodeled dynamics, external disturbance, and parameter uncertainties. To cope with these uncertainties in such uncertain nonlinear systems which is not fully-actuated, this paper proposes a control method that can actively estimate these uncertainties via the extended state observer (ESO), under the scheme of output-feedback control, the lumped uncertainties can be online estimated and actively compensated. Every joint of the underactuated robotic system can robustly reach the pre-given state in finite-time even though there are only fewer joints than the actual number of joints that can be controlled directly. The experimental results demonstrate the control process and validate that the proposed method is feasible for the studied underactuated robotic system.

scholarly journals Adaptive output feedback control for a class of uncertain non-strict feedback systems with asymmetric time-varying output constraints

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402095882
Author(s):  
Min Wan ◽  
Shanshan Huang
Keyword(s):  
Feedback Control ◽  
Output Feedback ◽  
Tracking Error ◽  
Output Feedback Control ◽  
Time Varying ◽  
Dynamic Surface ◽  
Adaptive Output Feedback Control ◽  
Output Constraints ◽  
Fuzzy State ◽  
Strict Feedback

This study investigated a novel adaptive output feedback control scheme for non-strict feedback nonlinear systems with uncertainties, disturbances, and asymmetric time-varying output constraints. Because that the states of the system are unmeasurable, we used an adaptive fuzzy state observer to obtain the estimated values of the states. To make the output and tracking error satisfy their asymmetric time-varying constraints, an asymmetric time-varying barrier Lyapunov function was adopted. To overcome the “explosion of complexity” problem, we also adopted the dynamic surface control technology. The stability of the closed-loop system was proved by the Lyapunov method, and we give two simulation examples to show the effectiveness of the proposed control method.

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