8 results about "Stability theory" patented technology

The application provides a hydraulic mechanical arm system fixed time compensation control method with input dead zone and unknown disturbance, and is aimed at a hydraulic mechanical arm system with input dead zone and unknown disturbance, and based on a backstepping design framework, a novel adaptive compensation controller with fixed time convergence is provided by using relevant mathematical lemmas and adaptive control technology. First, an observer is designed for parameter uncertainty and unknown disturbance of the system model by using the sliding mode control and fixed time theory, and the observer is compensated; second, a controller is designed based on the backstepping design framework; third, an input dead zone adaptive compensation mechanism is constructed based on Lyapunov stability theory. Simulation experiments show that the observer can well estimate and compensate the system output uncertainty caused by parameter uncertainty and unknown disturbance, and the system can maintain good tracking accuracy and realize rapid stability even if the system is affected by the input dead zone.

This invention discloses a fixed-time adaptive sliding mode control method and system for improving the disturbance rejection performance of downhole permanent magnet synchronous motors (PMSMs). The method includes: establishing a mathematical model of the PMSM considering parameter uncertainties and external load disturbances, defining parameter uncertainties and external load disturbances as lumped disturbances; constructing a fixed-time extended state observer to observe the lumped disturbances in real time based on fixed-time stability theory and obtain an estimate of the lumped disturbances; designing a fixed-time adaptive sliding mode control law based on the lumped disturbance estimate, generating a q-axis reference current, and realizing speed control of the PMSM; wherein, the adaptive sliding mode control law is derived by combining a non-singular fast terminal sliding surface, a fixed-time reaching law, an adaptive gain based on a variable gain rate smoothing factor, and the lumped disturbance estimate. This invention achieves fast and accurate convergence of disturbance errors within a fixed time.

The invention belongs to the technical field of random system control and sewage treatment, and discloses a T-S fuzzy Markov jump system control method based on an activated sludge system. According to the method, a nonlinear kinetic model is constructed from key state variables of the system, and the complex biological reaction and substance transfer process in sewage treatment is accurately described. By introducing the Markov jump theory, parameter random jump caused by inlet water quality sudden change and the like is effectively described, and the adaptability and accuracy of the model under the dynamic working condition are enhanced. For possible faults of an actuator (such as a dilution valve and an aerator), a fault model is established and a corresponding fault-tolerant control strategy is designed, so that the reliability and robustness of the system are improved. On the basis of the Lyapunov stability theory, a linear matrix inequality condition which enables the system to be randomly stable under the fault and disturbance and meets the H-infinity performance index is deduced, the effectiveness of the linear matrix inequality condition is verified through strict mathematical derivation, and a theoretical basis is provided for implementation of a controller and stable operation of the system.

The invention discloses an inverter grid-connected synchronous optimization control method based on a backstepping method, and belongs to the technical field of new energy grid-connected control, and the method comprises the steps: building a second-order nonlinear mathematical model of a phase-locked loop based on a grid-connected inverter phase-locked loop control structure, and deducing a state-space equation; decomposing the state space equation according to the state variable, and determining the virtual control quantity of each order of subsystem; defining an error variable by using the virtual control quantity, and recursively constructing a control law by using a backstepping method based on a Lyapunov asymptotic stability theory; and controlling the phase-locked loop by using the obtained control law to realize closed-loop control. According to the method, backstepping design is carried out on the phase-locked loop variable, on the premise that an original phase-locked loop structure is reserved, an additional control law is introduced, the robustness of the system under the condition that the power grid impedance is increased is remarkably improved due to the addition of the control law, the stability of voltage and current of a grid-connected point can be maintained, and the frequency hopping and instability risk can be effectively restrained.

This invention proposes a method and system for fixed-wing UAV habitat planning based on the attraction domain, belonging to the field of UAV control technology. The method includes step S1: acquiring the core state parameters and control parameters during the flight of the fixed-wing UAV; step S2: estimating the UAV's flight attraction domain based on the Lyapunov model, combined with the core state parameters and control parameters, to obtain an attraction domain set; and step S3: generating a reference flight trajectory based on the attraction domain set and landing target data. This invention also proposes a fixed-wing UAV habitat planning system based on the attraction domain. This invention ensures stable convergence throughout the entire UAV habitat landing process from the perspective of nonlinear system stability theory. Simultaneously, through lightweight modeling and simplified solution, it adapts to the onboard computing capabilities of small UAVs, effectively solving the core defects of existing technologies such as weak robustness, lack of stability guarantee, and complex calculations, enabling small fixed-wing UAVs to achieve precise habitat landing in small spaces without taxiing.

The invention relates to the technical field of electro-hydraulic position servo control systems of excavators, in particular to a trajectory tracking control method and device for a mechanical arm of an excavator, and the method comprises the following steps: S1, establishing a mathematical model of an electro-hydraulic position servo system of the mechanical arm; s2, identifying system parameters on line based on samples of a proportional pressure reducing valve and a multi-way valve of the excavator; s3, based on the mathematical model of the electro-hydraulic position servo system of the mechanical arm in the S1 and the identification parameters in the S2, a self-adaptive backstepping sliding mode controller based on a parameter layering strategy is designed, and tracking control is conducted on the track of the mechanical arm of the excavator through the self-adaptive backstepping sliding mode controller; and S4, a Lyapunov stability theory is used to carry out stability proving on the adaptive backstepping sliding mode controller in the S3, and an asymptotically stable system tracking error is obtained.

This invention discloses a sliding mode control method based on a neural network adaptive observer, belonging to the field of hydraulic position servo system control technology. The method involves: establishing a nonlinear mathematical model of the hydraulic servo system; designing a state observer based on a radial basis function neural network to estimate the states in the system, and designing the system's sliding mode control law using the observed parameters; designing a neural network adaptive law using Lyapunov stability theory; smoothing the controller output using a filter; and selecting appropriate controller hyperparameters to enable the system to achieve the desired control effect and accurately track the desired signal. The control strategy designed in this invention can estimate nonlinearities that are difficult to model online, accurately observe the system state, exhibit good steady-state performance, and is easy to apply in engineering.