Prescribed-time control weak disturbance decoupling problems for strict-feedback-like systems with unknown control...

Area of Science:

• Control Engineering
• Nonlinear Systems Theory
• Robotics

Background:

• Existing prescribed-time controllers face challenges with long-term operation due to ill-defined or non-differentiable adjustment functions.
• Disturbance decoupling has been a significant unaddressed issue in prescribed-time control.

Purpose of the Study:

• To design an adaptive controller for uncertain nonlinear systems that attenuates disturbances and bounds system output error at a prescribed time.
• To ensure bounded stability of system states in the absence of disturbances.

Main Methods:

• Smoothing existing prescribed-time adjustment functions using a linear combination of exponential functions for infinite-time differentiability.
• Defining a new weighted norm to handle system uncertainties and disturbances.
• Constructing an adaptive prescribed-time almost disturbance decoupling controller for strict-feedback-like nonlinear systems.

Main Results:

• The proposed controller effectively overcomes issues related to unbounded derivatives caused by non-differentiable functions in prior methods.
• Comparative simulations demonstrate superior performance over existing controllers, both before and after the prescribed time.
• The controller shows significant effectiveness in attenuating the impact of disturbances.

Conclusions:

• The developed adaptive prescribed-time controller offers improved performance and robustness for nonlinear systems with disturbances.
• The novel approach enhances the reliability and applicability of prescribed-time control in real-world scenarios like assembly line manipulators.
• The controller ensures arbitrarily small output error bounds at the prescribed time and bounded stability.