In this article, we study the formation control problem of multiple agents. In the past studies on sliding mode control, when the state trajectory reaches the sliding mode surface, it is difficult to strictly slide along the sliding mode surface to the equilibrium point, but it travels back and forth on both sides to approach the equilibrium point, resulting in chattering. This is also the main obstacle in the practical application of sliding mode control, and in actual scenarios, the agent has a limited communication distance and perception distance. In order to solve this problem, we propose a dynamic sliding mode control method. First, we establish an agent motion model to determine the leader and follower. The trajectory of the formation is deter-mined by the leader, and the follower agent maintains an ideal position in the leader coordinate system. Then, multiple agents conduct formation movement under the guidance of the leader. In this paper, two examples are used for simulation, and the simulation results show the effectiveness of the pro-posed formation control method.
At present, electromechanical actuator is very popular in the industrial field because of environmental protection, energy saving and high efficiency. At the same time, it also puts forward higher requirements for its reliability. In this paper, a fault tolerant nonsingular terminal sliding mode control method for electromechanical system based on support vector machine (SVM) is proposed. SVM is designed to estimate the possible faults in the system by off-line learning from large sample data with gradient descent method. The estimation is used to compensate the possible fault with feedforward cancellation technique in the proposed controller. An observer is designed to estimate the system states to make fault detection and reconstruct the controller when something is wrong in electromechanical system. A nonsingular terminal sliding mode surface is designed, and Lyapunov theorem is used to derive a parameter adaptation law for handling the parametric uncertainty and a nonsingular terminal sliding mode control law. It is guaranteed the proposed controller can achieve bounded stability. Extensive comparative simulation and experimental results illustrate the effectiveness and advancement of the proposed controller compared with several other main-stream controllers.
An algorithm for recognizing cracks through images is presented for detection of any crack in inner wall of long-distance natural gas pipeline under complicated environment. This algorithm has low requirement on the image quality, simple pre-processing procedure, takes single continuous image areas as individual part, and carries out fuzzy judgment on cracks by multiple threshold values and crack approaching factors. Experiments showed that the algorithm is simple, of high recognition efficiency and accurate judgment.
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