A Widely Adaptive Time-Delayed Control and Its Application to Robot Manipulators

We present a practical adaptive sliding-mode control approach, namely, the strong and stable adaptive sliding-mode control (SS-ASMC), in this paper. There is a significant effort towards addressing the technical challenges associated with the switching gains with two adaptive laws, which are called parent and child adaptive laws. A parent adaptive law helps achieve strong switching gains through fast adaptation rate when sliding variable moves away from the sliding manifold. A child adaptive law updates the parameter of the parent adaptive law, which helps to achieve the switching gains with fast and stable adaptation rate in the vicinity of the sliding manifold. Such switching gains with two adaptive laws provide remarkably precise tracking performance while enhancing the robustness. Besides, to yield desirable closed-loop poles and simplicity of control approach structure, the proposed SS-ASMC approach employs a combination of time-delayed estimation and pole-placement method, which makes it unnecessary to have a rather complete system dynamics. It is shown by the bounded-input-bounded-output stability through the Lyapunov approach, and thus the tracking errors are also proved to be uniformly ultimately bounded. The effectiveness of the proposed SS-ASMC approach is illustrated in simulations with robot manipulators, which is compared with that of the existing control approaches.

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“…According to the well-known assumption, it is assumed that the following property [23][24][25] holds…”

Section: The Dynamics Of Robot Manipulatormentioning

confidence: 99%

Practical Adaptive Sliding-Mode Control Approach for Precise Tracking of Robot Manipulators

Baek

Kwon

2020

Applied Sciences

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“…Theorem 2. The control law in (18) and (20), which utilizes the estimation value of the unmeasurable state, and the lumped disturbance from the ESO in (9) guarantee the ultimately uniformly bounded tracking performance and satisfaction of the output constraint in (17) of the manipulator described by (1), under unknown friction, external disturbance, and an unknown vector of the input dead-zone.…”

Section: Stability Analysismentioning

confidence: 99%

“…In recent years, robots have attracted the interest of many researchers in institutes, universities, and technology companies around the world [1]. Challenges such as highly nonlinear dynamics, modeling error, and external disturbances can degrade the control performance of the robotic manipulator.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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“…Involved auxiliary SMCs of the MC-SMs contribute to the suppression of inherent time-delay estimation (TDE) errors and subsequently improving the tracking performance. All of the above existing MC-SMs have linear sliding variables for achieving asymptotic stability in a simple manner [17], [18]. However, linear sliding variables are disadvan-tageous in that the corresponding control effort becomes insensitive to tracking errors as the joint angles approach the reference target values.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Model-Free Control With Nonsingular Terminal Sliding-Mode for Application to Robot Manipulators

Choi

Baek

Lee³

et al. 2020

IEEE Access

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An adaptive model-free control with nonsingular terminal sliding-mode (AMC-NTSM) is proposed for high precision motion control of robot manipulators. The proposed AMC-NTSM employs onesample delayed measurements to cancel nonlinearities and uncertainties of manipulators and to subsequently obtain sufficiently simple models for easy control design. In order to maintain high gain controls even when the joint angles are close to the reference target values and accordingly achieve high precision and fast response control, a nonlinear sliding variable is also adopted instead of a linear one, asymptotically stabilizing controls by guaranteeing even a finite-time convergence. In addition, sliding variables are reflected on control inputs to support fast convergence while achieving uniform ultimate boundedness of tracking errors. The control gains of the proposed AMC-NTSM are adaptively adjusted over time according to the magnitude of the sliding variable. Such adaptive control gains become high for fast convergence or low for settling down to steady motion with better convergence precision, when necessary. The switching gains of the proposed AMC-NTSM are also adaptive to acceleration such that inherent time delay estimation (TDE) errors can be suppressed effectively regardless of their magnitudes. The simulation and experiment show that the proposed AMC-NTSM has good tracking performance. INDEX TERMS Adaptive control, time-delay control, time-delay estimation, nonsingular terminal slidingmode, robot manipulator.

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A Widely Adaptive Time-Delayed Control and Its Application to Robot Manipulators

Cited by 70 publications

References 33 publications

Practical Adaptive Sliding-Mode Control Approach for Precise Tracking of Robot Manipulators

Practical Adaptive Sliding-Mode Control Approach for Precise Tracking of Robot Manipulators

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

Adaptive Model-Free Control With Nonsingular Terminal Sliding-Mode for Application to Robot Manipulators

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