A control scheme based on model-free adaptive control (MFAC) is presented for the input-constrained problem in this paper. Firstly, an equivalent linear system is established using the dynamic linearisation method. A ...
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Real-time and accurate monitoring of tool wear is an important link to realizing intelligent manufacturing, which has an important impact on product quality and production cost. Due to its convenience and strong nonli...
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ISBN:
(纸本)9798350321050
Real-time and accurate monitoring of tool wear is an important link to realizing intelligent manufacturing, which has an important impact on product quality and production cost. Due to its convenience and strong nonlinear mapping capability, deep learning has attracted extensive attention in the field of tool wear monitoring. However, the monitoring signal in the machining process will inevitably be interfered with by the noise from the machine tool, which will affect the models' reliability and optimization. In this work, the effectiveness of monitoring signals is analyzed, and a machine tool inherent characteristic frequency interception method and a time-frequency domain decoupling technique based on wavelet transform with tunable Q-factor are introduced to perform targeted noise removal during machining. The method is naturally interpretable. Meanwhile, a frequency-separation attention mechanism is proposed to weigh the frequency at different stages adaptively. The validity of the proposed method is verified by using real machining data. And the interpretability of the model is briefly analyzed.
The goal of this paper is to study model-free data-drivencontrol evaluation and design strategies for discrete-time linear time-invariant systems, where the system model is unknown. In particular, our main contributi...
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The goal of this paper is to study model-free data-drivencontrol evaluation and design strategies for discrete-time linear time-invariant systems, where the system model is unknown. In particular, our main contribution is twofold: 1) new state-input exploration and data collection schemes from experiences;2) new data-driven linear matrix inequalities and dynamic programming methods for stabilization and optimal control problems. The proposed exploration and data collection schemes theoretically guarantee to acquire sufficient information from the system's state-input trajectories that can solve the underlying control design problems. We prove that under mild assumptions, as more and more data is accumulated, the collected data can solve the problems with higher probability along with the proposed algorithms.
In view of the defects of noise in the industrial data of the oxygen-rich top blown smelting and time lag in off-line detection of matte grade, it is difficult to accurately establish the prediction model of process p...
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ISBN:
(纸本)9798350321050
In view of the defects of noise in the industrial data of the oxygen-rich top blown smelting and time lag in off-line detection of matte grade, it is difficult to accurately establish the prediction model of process parameters. A process parameter prediction model based on wavelet denoising sparrow search algorithm optimized support vector machine (WD-SSA-SVM) was proposed. Firstly, wavelet denoising is used to improve the quality of the data. Secondly, the sparrow search algorithm was used to optimize the support vector machine to establish the nonlinear relationship model between the melting process and the process index, and the model parameters were identified by the sample data after denoising, so as to effectively predict the process index of frosted sand grade in the process of the oxygen-rich top blown smelting. The experimental results on the actual production data of a smelter show that the WD-SSA-SVM model proposed in this paper has high accuracy, meets the accuracy requirements in the actual industrial production, and can effectively guide the optimization and adjustment of the operating parameters of the oxygen-rich top blown smelting process.
Various biological and abiotic factors influence the process of sludge bulking, showing a high degree of nonlinearity. Various inducing factors interact with each other and have strong coupling. In theory, the artific...
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ISBN:
(纸本)9798350321050
Various biological and abiotic factors influence the process of sludge bulking, showing a high degree of nonlinearity. Various inducing factors interact with each other and have strong coupling. In theory, the artificial neural network can approximate any nonlinear system with any precision, so it is determined to use a neural network algorithm for prediction. The Middle BP algorithm is the most common and effective method. This paper proposes a prediction method based on the BP neural network optimized by the grey wolf optimization algorithm and chaotic particle swarm optimization algorithm to predict the trend of sludge bulking, in which the grey wolf algorithm and messy particle swarm optimization method are used to optimize the neural network algorithm. This algorithm can solve the problems of the BP neural network in the early stage, such as convergence, easy falling into the local minimum value, too dependent on the early weight, and effectively improve the neural network's calculation speed and prediction accuracy.
As one efficient technique in reinforcement learning, policy iteration (PI) requires an initial admissible (or stabilizing for linear systems) control policy that renders the existing PI-based results to be model depe...
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As one efficient technique in reinforcement learning, policy iteration (PI) requires an initial admissible (or stabilizing for linear systems) control policy that renders the existing PI-based results to be model dependent. To attain a completely data-driven adaptive optimal control, this article suggests integrating a homotopic design with PI for unknown continuous-time nonlinear systems. Technically, we leverage a homotopic constant to construct an artificially stable system that allows zero control to initialize PI. Utilizing a homotopic strategy, we recursively update the artificial system and then enforce it to gradually recover the original system. This ultimately allows us to obtain an admissible control policy in a finite number of iterations without carrying out a model-based initialization. Once the admissible control is obtained, the proposed homotopic PI inherits fast convergence from the traditional PI technique and ensures learning the optimal control solution from the data measured from unknown nonlinear systems.
This work presents a novel learning Model Predictive control (LMPC) strategy for autonomous racing at the handling limit that can iteratively explore and learn unknown dynamics in high-speed operational domains. We st...
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ISBN:
(纸本)9798350384581;9798350384574
This work presents a novel learning Model Predictive control (LMPC) strategy for autonomous racing at the handling limit that can iteratively explore and learn unknown dynamics in high-speed operational domains. We start from existing LMPC formulations and modify the system dynamics learning method. In particular, our approach uses a nominal, global, nonlinear, physics-based model with a local, linear, data-drivenlearning of the error dynamics. We conducted experiments in simulation and on 1/10th scale hardware, and deployed the proposed LMPC on a full-scale autonomous race car used in the Indy Autonomous Challenge (IAC) with closed loop experiments at the Putnam Park Road Course in Indiana, USA. The results show that the proposed control policy exhibits improved robustness to parameter tuning and data scarcity. Incremental and safety-aware exploration toward the limit of handling and iterative learning of the vehicle dynamics in high-speed domains is observed both in simulations and experiments.
A Furuta pendulum is a typical underactuated mechanical system with two degrees of freedom (DOF) and only one input. We address the robust stabilization control problem for this 2-DOF underactuated system with a match...
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ISBN:
(纸本)9798350321050
A Furuta pendulum is a typical underactuated mechanical system with two degrees of freedom (DOF) and only one input. We address the robust stabilization control problem for this 2-DOF underactuated system with a matched external disturbance. A fixed-time sliding mode control method is presented. First, the dynamic motion model of the system is established using the Euler-Lagrange modeling method. And then, we get the approximate linearization model of the system around the origin equilibrium point and construct a homeomorphic coordinate transformation for this model. After that, a sliding mode surface and a fixed-time robust controller are designed for the transformed system. The developed controller ensures the system's state variables to reach the sliding mode surface in a fixed time. This guarantees the fixed-time robust stabilization control objective to be achieved. Finally, two numerical examples demonstrate the validity of our presented control strategy.
This paper presents a velocity planning method for autonomous vehicles (AVs) to guarantee safe interactions with pedestrians at unsignalized crosswalks and with surrounding vehicles on the AV's route. The method i...
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This paper presents a velocity planning method for autonomous vehicles (AVs) to guarantee safe interactions with pedestrians at unsignalized crosswalks and with surrounding vehicles on the AV's route. The method is structured within a hierarchical framework that includes robust control, a learning-based component, and a supervisory element. The learning-based component is trained using reinforcement learning techniques to reduce traveling time, minimize control interventions, and set the priority ratio between the AV and pedestrians. The supervisory element employs scenario optimization, using statistical data on pedestrian motions to ensure collision avoidance. A complex game-theory-based pedestrian model is formulated and analyzed in order to evaluate the effectiveness of the proposed velocity planning method. Extensive simulations are performed using the high-precision traffic simulator software SUMO. These simulations evaluate various aspects of the velocity planner, including computation time, traveling time, control interventions, and parameter settings. The results demonstrate the method's ability to achieve real-time implementation while maintaining safety and performance objectives.
This paper develops a novel method named wavelet denoising convolutional neural network (WDECNN) for fault diagnosis with background noise. The continuous wavelet transform (CWT) is first applied to transform the meas...
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ISBN:
(纸本)9798350321050
This paper develops a novel method named wavelet denoising convolutional neural network (WDECNN) for fault diagnosis with background noise. The continuous wavelet transform (CWT) is first applied to transform the measured raw vibration data into time-frequency images which serve as the inputs of WDECNN. Then, a light-weight two-dimensional CNN (2DCNN) model is incorporated in WDECNN to simplify the network architecture, while a wavelet denoising module is also applied in it to achieve high accuracy of fault identification in the noisy environment. Particularly, the wavelet denoising module which consists of wavelet decomposition and denoising is parallel to the 2DCNN model, and the denoising results are integrated into pooling layers in the 2DCNN model. Thus, the denoised information is added to the 2DCNN model to improve its feature learning ability. Finally, the effectiveness of the developed method is validated on Paderborn bearing dataset, which illustrates its fault diagnosis capability under background noise.
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