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The steel industry has received serious attention under the background of carbon neutralization and carbon peaking. However, the traditional end-to-end energy consumption (EC) prediction method does not consider the effects of multi-step rolling, multi-time series, and error accumulation. To this end, a series-concatenation model based on a two-stage hybrid network is proposed to achieve EC high-precision prediction in multi-step continuous rolling. Specifically. First, this paper analyzed the mechanism between rolling EC and multiple variables. Second, a two-stage hybrid network with a deep neural network block, convolutional neural network block, long short-term memory block, and SoftBoost block (DCLS-Net) is established for EC prediction of single-step rolling. SoftBoost block is a double-layer structure method proposed in this paper for multi-block precision improvement based on two kinds of boosting strategies. Last, according to the error mechanism and multi-time series characteristics in the multi-step rolling, a series-concatenation EC prediction model is designed to suppress errors and achieve high-precision prediction. The experimental results show that the SoftBoost can effectively improve prediction performance. And the prediction precision of the two-stage DCLS-Net for single-step rolling is improved by 9.43% on average compared with the end-to-end machine learning algorithm. Furthermore, the precision of the series-concatenation model for multi-step rolling is improved by 4.96% compared with the traditional series model, which can satisfy the requirements of high accuracy and positive error in strip rolling production. Note to Practitioners—The inspiration for this paper mainly comes from the multi-objective process planning problem in the hot multi-step continuous roughing process, especially the energy consumption target. This method is also applicable to other variable prediction problems in the continuous multi-step process industry. The common method of energy consumption prediction is end-to-end machine learning. However, the characteristics of multi-step rolling and multi-time series, as well as the influence of intermediate process variables on the results, are not considered, which makes the precision and reliability of prediction unable to satisfy the requirements of industrial production. In this paper, the series-concatenation model structure is adopted to realize the high-precision energy consumption prediction and error suppression of multi-step rolling of strip steel. Such research is helpful for engineers to understand the energy consumption mechanism of strip rolling. It provides guidance for multi-objective roughing process planning. In future research, we will study the influence of more process variables on energy consumption.

The steel industry is the key industry of energy consumption. The optimization of rolling process parameters is an effective measure to reduce and optimize energy consumption. Accurate energy consumption prediction has an indispensable guiding function in the planning of process parameters. However, the traditional energy consumption prediction and machine learning methods have been unable to fit the needs of high precision and reliability. Taking the horizontal roughing process (HRP) of hot rolling process as the research object, this paper mainly introduces an energy consumption prediction mechanism model (ECPMM) based on a roller adaptive wear strategy by analyzing the strip forming mechanism and rolling process. Then, two directions adaptive differential evolution (TDADE) algorithm is proposed based on a novel adaptive strategy. This algorithm has better convergence speed and global optimization ability than other optimization algorithms in the parameter optimization of ECPMM. We carried out comparative experiments on five machine learning algorithms. The results show that the ECPMM optimized by TDADE is superior to the five machine learning algorithms in prediction accuracy and stability. Finally, we conducted ablation experiments on the energy consumption characteristics of the HRP process, which turns out that using a smaller reduction and roller radius can reduce energy consumption. Summarizing the above experimental results suggests that the ECPMM has high accuracy and robustness, and satisfies the requirements of practical application. Note to Practitioners—It is necessary to carry out the deep analysis and research of energy consumption prediction involved in the process planning of strip hot rolling, the inspiration of this article is stem from this point. The commonly used energy consumption prediction methods include mechanism modeling and machine learning, but both have disadvantages, like low prediction accuracy and black box, which must have to be performed to solve by adapting the production demand of high reliability. In this paper, the combination of the mechanism model and data-driven method is used to realize the accurate prediction of energy consumption and improve the reliability of the model. To the best of our knowledge, this is the first paper about the research on energy consumption prediction of hot rolling process based on mechanism model and data-driven, especially in data size, time granularity, algorithm design, and prediction performance. Such research is helpful to guide engineers to design rolling energy consumption. We will dive a bit deeper into learning the energy consumption and process parameters during the rolling process in future studies.

Extensive research has been dedicated to reinforcement learning (RL) for acquiring proficient optimal controllers through interactions with the environment. However, real-world demands, including enhanced safety performance, introduce considerable challenges to the present design of optimal controllers rooted in RL algorithms. A novel approach is introduced in this article for designing RL-based optimal controllers, employing a control barrier function (CBF) alongside a nonquadratic loss function related to the control signal. The aim is to enable the agent to learn the optimal controller in a secure and efficient manner. To tackle the instability issue in neural network training inherent to traditional RL-based controller design processes, the nonlinear model predictive control (NMPC) technique is employed for initializing the controller network’s weights. A formal demonstration of the method’s optimality is presented. Numerical simulations validate the proposed approach, illustrating its capacity to effectively learn the optimal controller while adhering to the input and state constraints of the system.

The policy gradient adaptive dynamic programming (PGADP) technique has gained recognition as an effective approach for optimizing the performance of nonlinear systems. Nonetheless, existing PGADP algorithms often demand a substantial volume of expensive or potentially risky interaction data with the system. Moreover, the utilization of neural networks in these algorithms can result in suboptimal learning efficiency and unstable training procedures. To address these challenges, a novel algorithm, referred to as OptNet-PGADP, has been introduced. This algorithm integrates an initially tailored control policy based on OptNet to tackle the optimization of control problems in discrete-time nonlinear systems. The OptNet-PGADP algorithm operates through a two-step process. Initially, the input–output trajectory of the system is computed using the nonlinear model predictive control (NMPC) method. Subsequently, an initial admissible control policy is acquired through OptNet. This policy is iteratively enhanced using the PGADP algorithm to attain the optimal controller. The resulting closed-loop control policy can be readily deployed in real-time applications. The implementation of the algorithm employs OptNet for the actor network and integrates an experience replay mechanism to bolster the controller’s learning efficiency. Furthermore, a convergence and optimality analysis of the algorithm is included. Simulation and experimental results conducted on two nonlinear systems conclusively demonstrate that the approach outperforms traditional PGADP and NMPC algorithms. These findings underscore the efficacy of OptNet-PGADP in mitigating the constraints of current methods and achieving superior control performance for nonlinear systems.