Adaptive event trigger control method for nonlinear uncertain system

Abstract

The invention discloses an adaptive event trigger control method for a nonlinear uncertain system, which comprises the steps of firstly, for an input saturation phenomenon, adopting a smooth hyperbolic tangent function to approximate the saturation characteristic of system control input so as to avoid the phenomenon of unsmooth control input and facilitate the subsequent design; secondly, for an uncertain part of the system, improving the traditional Fuzzy Logic Systems (FLSs) to a certain extent, and taking the time-varying approximation error of an approximation system into consideration; finally, providing an event trigger control mechanism of a dynamic threshold for the bandwidth constraint existing in the actual system, wherein the trigger threshold changes along with the change of the control quantity at the last moment, so that more precise and flexible control can be realized, and the system bandwidth resources can be better saved on the basis of ensuring the control effect.

Description

technical field [0001] The invention relates to the technical field of system control, in particular to an adaptive event-triggered control method for nonlinear uncertain systems. Background technique [0002] As science and technology develop, practical systems such as robots, motors, and inverted pendulums become more and more complex. However, the actual system often suffers from a variety of constraints. The input saturation problem caused by the constraints of the mechanical structure and physical devices is ubiquitous: the input saturation problem will lead to the loss of the control input part, resulting in the loss of the control force of the system. Thus further affecting the control performance of the system. For the processing of input saturation, most of the traditional methods use a switching function to process the control input. When the value of the control input exceeds a specific threshold, the value of the control input is equivalent to the threshold for ...

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Problems solved by technology

However, the actual system often suffers from a variety of constraints. The input saturation problem caused by the constraints of the mechanical structure and physical devices is ubiquitous: the input saturation problem will lead to the loss of the control input part, resulting in the loss of the control force of the system. which further affects the control performance of the system

For the processing of input saturation, most of the traditional methods use a switching function to process the control input. When the value of the control input exceeds a specific threshold, the value of the control input is equivalent to the threshold for processing; this processing method is relatively simple and also It has a good effect, but there is a problem at the same time, that is, when the value of the control input is equivalent to the threshold value, a corner will appear on the curve of the control input, which will cause the control input to be not smooth, resulting in the subsequent use of Backstepping technology cannot be directly applied to the control design of the system

[0003] In addition, the actual system often has uncertain parts, how to properly deal with the uncertain parts of the system, which has a great impact on the performance of the system

Most of the traditional methods use neural networks (NNs) or fuzzy logic systems (FLSs) to approximate the uncertain part of the system, and then incorporate the obtained estimates into the design of the control system; such methods can also better solve this problem , the approximation system often has an approximation error, and the traditional method often treats it as a bounded constant for easy processing. However, the actual approximation error is time-varying. When the system control accuracy is high, the approximation error The problem will be further highlighted

[0004] Finally, the bandwidth resources of the actual system are often limited. When the system control force needs to be changed quickly to ensure the system performance, the transmission pressure of the system increases sharply; for this problem, the first proposed solution is periodic control, namely Set a specific cycle according to the actual situation, trigger once in each cycle, update the control input of the system, and save system bandwidth resources while ensuring system performance; however, this method lacks flexibility

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