Pub Date : 2026-04-01Epub Date: 2026-01-15DOI: 10.1016/j.conengprac.2026.106768
Julian Landauer , Paul Dollhäubl , Stefan Fuchshumer , Wilhelm Posch , Andreas Kugi , Andreas Steinboeck
In continuous casting of steel slabs, the ferrostatic pressure in the liquid core of the strand causes bending (also called bulging) of the strand shell between the guiding rolls. Unsteady bulging refers to a time-varying bending of the strand shell, leading to unwanted mold level fluctuations that can degrade the quality of the cast strand. Most mold level controller designs presented in the literature do not explicitly account for this disturbance due to the absence of suitable unsteady bulging models. As a result, these controllers often fail to sufficiently suppress unsteady bulging or even provoke it. This work presents a novel robust model-based controller design that systematically considers unsteady bulging by incorporating a control-oriented unsteady bulging model. Unlike previous approaches, the proposed method also accounts for variations in plant parameters to ensure robust suppression of unsteady bulging and consistent control performance across the entire range of operating conditions. The proposed controller is validated on industrial continuous slab casters, where it is now permanently used and achieves a significant reduction in mold level fluctuations.
{"title":"Robust control design to prevent unsteady bulging in continuous slab casters","authors":"Julian Landauer , Paul Dollhäubl , Stefan Fuchshumer , Wilhelm Posch , Andreas Kugi , Andreas Steinboeck","doi":"10.1016/j.conengprac.2026.106768","DOIUrl":"10.1016/j.conengprac.2026.106768","url":null,"abstract":"<div><div>In continuous casting of steel slabs, the ferrostatic pressure in the liquid core of the strand causes bending (also called bulging) of the strand shell between the guiding rolls. Unsteady bulging refers to a time-varying bending of the strand shell, leading to unwanted mold level fluctuations that can degrade the quality of the cast strand. Most mold level controller designs presented in the literature do not explicitly account for this disturbance due to the absence of suitable unsteady bulging models. As a result, these controllers often fail to sufficiently suppress unsteady bulging or even provoke it. This work presents a novel robust model-based controller design that systematically considers unsteady bulging by incorporating a control-oriented unsteady bulging model. Unlike previous approaches, the proposed method also accounts for variations in plant parameters to ensure robust suppression of unsteady bulging and consistent control performance across the entire range of operating conditions. The proposed controller is validated on industrial continuous slab casters, where it is now permanently used and achieves a significant reduction in mold level fluctuations.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106768"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to develop a high–performance Maximum Power Point Tracking (MPPT) strategy for Photovoltaic (PV) systems, with the objective of achieving fast convergence, minimal oscillations, and stable operation under rapidly changing irradiance. The nonlinear behavior of PV systems poses a significant challenge to meeting these goals and maximizing harvested energy. To address this, the paper presents a dynamic MPPT strategy that leverages PV characteristics through an Artificial Neural Network (ANN) trained using graph–based data processing methods to estimate the reference voltage. The neural estimator is integrated with a dynamic recurrent neurocontroller, which is trained via the Real–Time Recurrent Learning (RTRL) algorithm. To ensure system stability, a Lyapunov–based adaptive learning rate is applied to dynamic ANN–RTRL. Simulation studies were first performed to assess the effectiveness and robustness of the proposed ANN under varying meteorological conditions, and the results were subsequently validated experimentally using a Chroma PV emulator and a dSPACE 1202 MicroLabBox. The ANN performance was also compared with conventional, advanced, optimization, and intelligent algorithms under severe environmental fluctuations. The proposed ANN–RTRL was experimentally benchmarked against two reference methods: an ANN using the Least Mean Squares (ANN–LMS) algorithm and a conventional Perturb and Observe (P&O) with a Proportional–Integral (PI) controller. Results under both standard and rapidly varying irradiance conditions show that ANN–RTRL and ANN–LMS achieve tracking efficiencies above 99%, with reduced oscillations and improved precision. Notably, ANN–RTRL exhibits superior robustness and reaches the Maximum Power Point (MPP) 58% faster than ANN–LMS and 5% faster than P&O–PI, confirming its suitability for high–performance, real–time PV MPPT applications.
{"title":"Experimental implementation of neural network integration into a dynamic recurrent neurocontroller in PV system application","authors":"Mustapha Meraouah , Faiza Kaddari , Said Hassaine , Sandrine Moreau , Youcef Mihoub","doi":"10.1016/j.conengprac.2025.106753","DOIUrl":"10.1016/j.conengprac.2025.106753","url":null,"abstract":"<div><div>This study aims to develop a high–performance Maximum Power Point Tracking (MPPT) strategy for Photovoltaic (PV) systems, with the objective of achieving fast convergence, minimal oscillations, and stable operation under rapidly changing irradiance. The nonlinear behavior of PV systems poses a significant challenge to meeting these goals and maximizing harvested energy. To address this, the paper presents a dynamic MPPT strategy that leverages PV characteristics through an Artificial Neural Network (ANN) trained using graph–based data processing methods to estimate the reference voltage. The neural estimator is integrated with a dynamic recurrent neurocontroller, which is trained via the Real–Time Recurrent Learning (RTRL) algorithm. To ensure system stability, a Lyapunov–based adaptive learning rate is applied to dynamic ANN–RTRL. Simulation studies were first performed to assess the effectiveness and robustness of the proposed ANN under varying meteorological conditions, and the results were subsequently validated experimentally using a Chroma PV emulator and a dSPACE 1202 MicroLabBox. The ANN performance was also compared with conventional, advanced, optimization, and intelligent algorithms under severe environmental fluctuations. The proposed ANN–RTRL was experimentally benchmarked against two reference methods: an ANN using the Least Mean Squares (ANN–LMS) algorithm and a conventional Perturb and Observe (P&O) with a Proportional–Integral (PI) controller. Results under both standard and rapidly varying irradiance conditions show that ANN–RTRL and ANN–LMS achieve tracking efficiencies above 99%, with reduced oscillations and improved precision. Notably, ANN–RTRL exhibits superior robustness and reaches the Maximum Power Point (MPP) 58% faster than ANN–LMS and 5% faster than P&O–PI, confirming its suitability for high–performance, real–time PV MPPT applications.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106753"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For large-scale hydraulic manipulators (LHMs) equipped on non-road mobile machines, tool-center-point (TCP) control offers significant potential for alleviating operational burden. However, conventional TCP controllers designed for industrial manipulators generally fail to achieve high accuracy trajectory tracking for LHMs, due to the complex coupling properties of rigidity, flexibility and hydraulic nonlinearity. A dual-timescale dynamic decoupling framework is proposed to facilitate the design of high-accuracy TCP controllers for LHMs in engineering applications. Firstly, an accurate multibody flexible dynamic model of the LHM is established, and both of the rigid motion and elastic deformation are expressed in the generalized coordinate frame. The generalized coordinates and the system stiffness are extended in timescale based on the singular perturbation (SP) theory, so that the dynamic model of the LHM can be decomposed into two low-order independent subsystems. Further, the TCP controller is directly designed based on the decoupled model. It is validated on a concrete pumping spreader with a 13 m LHM. The maximum trajectory tracking error can be maintained within ±0.25 m when 2 of the 3 DOFs of the LHM are actuated, while the TCP can rapidly return to a stable state within 6.5 s following an external instantaneous excitation. Compared with the controller designed based on the undecomposed model, these two indicators are reduced by 30.04% and 55.45%, respectively. The results validate the effectiveness of the proposed method for engineering applications.
对于装备在非道路移动机械上的大型液压机械手(lhm),工具中心点(TCP)控制为减轻操作负担提供了巨大的潜力。然而,由于工业机械臂的刚度、柔性和液压非线性等复杂耦合特性,传统的TCP控制器无法实现对机械臂的高精度轨迹跟踪。提出了一种双时间尺度动态解耦框架,以方便工程应用中LHMs高精度TCP控制器的设计。首先,建立了精确的多体柔性动力学模型,将其刚性运动和弹性变形均表示为广义坐标系;基于奇异摄动(SP)理论,对广义坐标和系统刚度进行了时间尺度上的扩展,从而将LHM动力学模型分解为两个低阶独立子系统。在此基础上,直接设计了TCP控制器。在13 m LHM的混凝土泵送撒布机上进行了验证。当LHM的3个dof中的2个被驱动时,最大轨迹跟踪误差可以保持在±0.25 m以内,而TCP在外部瞬时激励后可以在6.5 s内快速恢复到稳定状态。与基于未分解模型设计的控制器相比,这两个指标分别降低了30.04%和55.45%。结果验证了该方法在工程应用中的有效性。
{"title":"High-accuracy tool-center-point trajectory tracking of large-scale hydraulic manipulators using dual-timescale dynamic decoupling","authors":"Junhui Zhang , Zhiwei Chen , Ruqi Ding , Weidi Huang , Min Cheng , Huaizhi Zong , Ruiheng Jia , Bing Xu","doi":"10.1016/j.conengprac.2025.106739","DOIUrl":"10.1016/j.conengprac.2025.106739","url":null,"abstract":"<div><div>For large-scale hydraulic manipulators (LHMs) equipped on non-road mobile machines, tool-center-point (TCP) control offers significant potential for alleviating operational burden. However, conventional TCP controllers designed for industrial manipulators generally fail to achieve high accuracy trajectory tracking for LHMs, due to the complex coupling properties of rigidity, flexibility and hydraulic nonlinearity. A dual-timescale dynamic decoupling framework is proposed to facilitate the design of high-accuracy TCP controllers for LHMs in engineering applications. Firstly, an accurate multibody flexible dynamic model of the LHM is established, and both of the rigid motion and elastic deformation are expressed in the generalized coordinate frame. The generalized coordinates and the system stiffness are extended in timescale based on the singular perturbation (SP) theory, so that the dynamic model of the LHM can be decomposed into two low-order independent subsystems. Further, the TCP controller is directly designed based on the decoupled model. It is validated on a concrete pumping spreader with a 13 m LHM. The maximum trajectory tracking error can be maintained within ±0.25 m when 2 of the 3 DOFs of the LHM are actuated, while the TCP can rapidly return to a stable state within 6.5 s following an external instantaneous excitation. Compared with the controller designed based on the undecomposed model, these two indicators are reduced by 30.04% and 55.45%, respectively. The results validate the effectiveness of the proposed method for engineering applications.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106739"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-29DOI: 10.1016/j.conengprac.2026.106809
Yiming Liu , Zhaojian Wang , Ruanming Huang , Bo Yang
This paper proposes a multi-objective control framework for wake-affected wind farms to manage the trade-off between power maximization and fatigue load minimization. The conflicting objectives are formulated using Nash bargaining theory, providing a fair, Pareto-efficient solution without heuristic weight tuning. A Warm-started Proximal Alternating Direction Method of Multipliers (W-PADMM) algorithm is proposed to efficiently solve the bargaining problem, which embeds a learning-aided mechanism using a Long Short-Term Memory (LSTM) network to proactively guide the optimization. Case studies on both an illustrative 9-turbine system and a real offshore wind farm under seasonally varying wind conditions demonstrate that the proposed W-PADMM approach achieves an improved power-fatigue trade-off together with substantial computational acceleration.
{"title":"Nash bargaining for power-fatigue co-optimization in wake-affected wind farms: A learning-aided approach","authors":"Yiming Liu , Zhaojian Wang , Ruanming Huang , Bo Yang","doi":"10.1016/j.conengprac.2026.106809","DOIUrl":"10.1016/j.conengprac.2026.106809","url":null,"abstract":"<div><div>This paper proposes a multi-objective control framework for wake-affected wind farms to manage the trade-off between power maximization and fatigue load minimization. The conflicting objectives are formulated using Nash bargaining theory, providing a fair, Pareto-efficient solution without heuristic weight tuning. A Warm-started Proximal Alternating Direction Method of Multipliers (W-PADMM) algorithm is proposed to efficiently solve the bargaining problem, which embeds a learning-aided mechanism using a Long Short-Term Memory (LSTM) network to proactively guide the optimization. Case studies on both an illustrative 9-turbine system and a real offshore wind farm under seasonally varying wind conditions demonstrate that the proposed W-PADMM approach achieves an improved power-fatigue trade-off together with substantial computational acceleration.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106809"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-25DOI: 10.1016/j.conengprac.2026.106803
Eyyup Sincar , Zeki Y. Bayraktaroglu , Eray A. Baran , Evren Emre
This paper introduces a unified joint–task-space control framework for a 6-DoF Stewart platform that overcomes the limitations of pure joint-space methods, including inverse-kinematic ambiguities, configuration flips, and sensitivity to dynamic variations. The proposed architecture integrates a nonsingular fast terminal sliding mode (NFTSM) controller, a nonlinear disturbance observer, and model-based feedforward compensation in the joint space, together with a complementary NFTSM-based task-space controller that continuously refines end-effector motion through Jacobian feedback. A rigorous Lyapunov analysis establishes finite-time convergence and robustness under modeling uncertainties and external disturbances. Extensive experiments—including sinusoidal and square-wave tracking, frequency-sweep tests, and payload variations—demonstrate that the unified controller consistently achieves the lowest tracking errors, superior robustness to excitation frequency and load changes, and smoother actuator effort without increasing energy consumption. The results confirm the suitability of the proposed method for high-precision parallel manipulators operating in dynamic, uncertain, and disturbance-rich environments.
{"title":"Robust unified dual-domain control framework for high-performance parallel robots","authors":"Eyyup Sincar , Zeki Y. Bayraktaroglu , Eray A. Baran , Evren Emre","doi":"10.1016/j.conengprac.2026.106803","DOIUrl":"10.1016/j.conengprac.2026.106803","url":null,"abstract":"<div><div>This paper introduces a unified joint–task-space control framework for a 6-DoF Stewart platform that overcomes the limitations of pure joint-space methods, including inverse-kinematic ambiguities, configuration flips, and sensitivity to dynamic variations. The proposed architecture integrates a nonsingular fast terminal sliding mode (NFTSM) controller, a nonlinear disturbance observer, and model-based feedforward compensation in the joint space, together with a complementary NFTSM-based task-space controller that continuously refines end-effector motion through Jacobian feedback. A rigorous Lyapunov analysis establishes finite-time convergence and robustness under modeling uncertainties and external disturbances. Extensive experiments—including sinusoidal and square-wave tracking, frequency-sweep tests, and payload variations—demonstrate that the unified controller consistently achieves the lowest tracking errors, superior robustness to excitation frequency and load changes, and smoother actuator effort without increasing energy consumption. The results confirm the suitability of the proposed method for high-precision parallel manipulators operating in dynamic, uncertain, and disturbance-rich environments.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106803"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-14DOI: 10.1016/j.conengprac.2026.106763
Bo Meng , Ke Zhang , Bin Jiang
This paper is dedicated to addressing fault-tolerant control and collision avoidance problems for fixed-wing unmanned aerial vehicles with engine degradation, control surface faults, and external disturbances. Primarily, a trajectory planning layer is developed based on the fully actuated system approach and the artificial potential function. In this framework, the projection of the relative velocity and the relative distance are fed into a fuzzy logic system to determine the collision avoidance potential intensity. Subsequently, the dynamic model of the fixed-wing unmanned aerial vehicle is divided into the translational and rotational dynamics subsystems, with control protocols designed separately via the fully actuated system approach. Simultaneously, adaptive disturbance observers are constructed to compensate for composite disturbances without prior knowledge of bounds. Moreover, to better align with practical flight control, the rotational subsystem is split into two channels. Reference signals for each channel are derived from the nonlinear guidance law and coordinated turn principle, and the Nussbaum function handles unknown control directions. Finally, the effectiveness of the proposed strategy is validated through simulation and comparative studies.
{"title":"Hierarchical structure-based adaptive fault-tolerant control and collision avoidance for multiple fixed-wing UAVs: A fully actuated system approach","authors":"Bo Meng , Ke Zhang , Bin Jiang","doi":"10.1016/j.conengprac.2026.106763","DOIUrl":"10.1016/j.conengprac.2026.106763","url":null,"abstract":"<div><div>This paper is dedicated to addressing fault-tolerant control and collision avoidance problems for fixed-wing unmanned aerial vehicles with engine degradation, control surface faults, and external disturbances. Primarily, a trajectory planning layer is developed based on the fully actuated system approach and the artificial potential function. In this framework, the projection of the relative velocity and the relative distance are fed into a fuzzy logic system to determine the collision avoidance potential intensity. Subsequently, the dynamic model of the fixed-wing unmanned aerial vehicle is divided into the translational and rotational dynamics subsystems, with control protocols designed separately via the fully actuated system approach. Simultaneously, adaptive disturbance observers are constructed to compensate for composite disturbances without prior knowledge of bounds. Moreover, to better align with practical flight control, the rotational subsystem is split into two channels. Reference signals for each channel are derived from the nonlinear guidance law and coordinated turn principle, and the Nussbaum function handles unknown control directions. Finally, the effectiveness of the proposed strategy is validated through simulation and comparative studies.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106763"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-17DOI: 10.1016/j.conengprac.2026.106791
Hui Xie , Sihan Chen , Gang Shen , Shuhui Fei , Yu Tang , Yongcun Guo , Yuanjing He
To address the challenges of inconsistent shoe-approaching motion and excessive transient impacts in the operation of multi-channel braking systems (MCBS) for mine hoists, this investigation presents a novel hybrid shoe-approaching/pressure control strategy utilizing real-time braking pressure feedback. First, the braking process is divided into two distinct stages: shoe-approaching motion and contact compression. A hybrid position/force switching control scheme, relying on braking pressure feedback, is developed using hysteresis switching principle. Second, an online fastest shoe-approaching trajectory planning algorithm is designed with a nonlinear filter, and a three-loop shoe-approaching control strategy is proposed, which consists of an outer loop for shoe-approaching trajectory planning, an inner loop for position tracking of brake, and a cross coupled loop for multi-channel synchronous shoe-approaching motion. Finally, two sets of comparative experiments are carried out on the multi-channel braking test bench of the hoist. The experimental results indicate that, compared with the traditional braking control mode, the proposed braking control strategy can effectively suppress the braking transient impact, shorten the shoe-approaching time, and enhance the consistency of shoe-approaching motion of the MCBS.
{"title":"Hybrid shoe-approaching and pressure control strategy for multi-channel braking systems of mine hoists","authors":"Hui Xie , Sihan Chen , Gang Shen , Shuhui Fei , Yu Tang , Yongcun Guo , Yuanjing He","doi":"10.1016/j.conengprac.2026.106791","DOIUrl":"10.1016/j.conengprac.2026.106791","url":null,"abstract":"<div><div>To address the challenges of inconsistent shoe-approaching motion and excessive transient impacts in the operation of multi-channel braking systems (MCBS) for mine hoists, this investigation presents a novel hybrid shoe-approaching/pressure control strategy utilizing real-time braking pressure feedback. First, the braking process is divided into two distinct stages: shoe-approaching motion and contact compression. A hybrid position/force switching control scheme, relying on braking pressure feedback, is developed using hysteresis switching principle. Second, an online fastest shoe-approaching trajectory planning algorithm is designed with a nonlinear filter, and a three-loop shoe-approaching control strategy is proposed, which consists of an outer loop for shoe-approaching trajectory planning, an inner loop for position tracking of brake, and a cross coupled loop for multi-channel synchronous shoe-approaching motion. Finally, two sets of comparative experiments are carried out on the multi-channel braking test bench of the hoist. The experimental results indicate that, compared with the traditional braking control mode, the proposed braking control strategy can effectively suppress the braking transient impact, shorten the shoe-approaching time, and enhance the consistency of shoe-approaching motion of the MCBS.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106791"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-12DOI: 10.1016/j.conengprac.2025.106756
Marco Fernandes dos Santos Xaud , Pål Johan From , Antonio Candea Leite
This paper presents the mechanical design, constructive aspects, kinematic modeling and control design methodology for a hyper-constrained parallel mechanism (HCPM), composed of six closed kinematic chains and twelve spherical joints, which is developed to carry out high-precision robotic tasks in industrial and agricultural environments. Here, we employ a systematic modeling methodology which considers the kinematic constraints of the mechanism from its structure equations, rather than explicitly using the constraint equations. This allows us to describe the kinematic constraints in the operation velocity space instead of the joint configuration space. From this analytical approach, we can compute the velocity of the non-actuated joints as a function of the velocity of the actuated ones. The control design uses an inverse kinematics algorithm based on the pseudo-inverse Jacobian matrix. In order to deal with many potential singular configurations which may occur during the task execution, we consider a recently proposed approach, called the Filtered Inverse method, which dynamically estimates the inverse of the Jacobian matrix instead of computing its true inverse instantaneously. The dynamic control of the HCPM is achieved using a simplified, Lagrangian-derived model to provide the computed-torque feedforward term for nonlinear compensation and decoupling, enabling motion simulation for high-speed trajectories while dismissing the need for a full explicit model, which is complex and difficult to obtain. Despite the simplifications, a robust cascade control strategy is proposed—featuring a second-order sliding mode (STA) compensator—to handle modeling uncertainties effectively. 3D computer modeling, numerical simulations, and laboratory experiments with two prototypes of the hyper-constrained parallel mechanism were conducted to validate the proposed approach and demonstrate its feasibility for high-precision robotic tasks.
{"title":"Modeling and cascade-based robust dynamic control of a hyper-constrained parallel mechanism for high-precision robotic tasks","authors":"Marco Fernandes dos Santos Xaud , Pål Johan From , Antonio Candea Leite","doi":"10.1016/j.conengprac.2025.106756","DOIUrl":"10.1016/j.conengprac.2025.106756","url":null,"abstract":"<div><div>This paper presents the mechanical design, constructive aspects, kinematic modeling and control design methodology for a hyper-constrained parallel mechanism (HCPM), composed of six closed kinematic chains and twelve spherical joints, which is developed to carry out high-precision robotic tasks in industrial and agricultural environments. Here, we employ a systematic modeling methodology which considers the kinematic constraints of the mechanism from its structure equations, rather than explicitly using the constraint equations. This allows us to describe the kinematic constraints in the operation velocity space instead of the joint configuration space. From this analytical approach, we can compute the velocity of the non-actuated joints as a function of the velocity of the actuated ones. The control design uses an inverse kinematics algorithm based on the pseudo-inverse Jacobian matrix. In order to deal with many potential singular configurations which may occur during the task execution, we consider a recently proposed approach, called the Filtered Inverse method, which dynamically estimates the inverse of the Jacobian matrix instead of computing its true inverse instantaneously. The dynamic control of the HCPM is achieved using a simplified, Lagrangian-derived model to provide the computed-torque feedforward term for nonlinear compensation and decoupling, enabling motion simulation for high-speed trajectories while dismissing the need for a full explicit model, which is complex and difficult to obtain. Despite the simplifications, a robust cascade control strategy is proposed—featuring a second-order sliding mode (STA) compensator—to handle modeling uncertainties effectively. 3D computer modeling, numerical simulations, and laboratory experiments with two prototypes of the hyper-constrained parallel mechanism were conducted to validate the proposed approach and demonstrate its feasibility for high-precision robotic tasks.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106756"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper addresses the position and attitude control of combined spacecraft in on-orbit servicing missions, taking into account model parameter uncertainties, unknown external disturbances, and fuel-optimal constraints. A novel flexible prescribed-performance optimal backstepping controller without initial constraints is proposed by incorporating an Actor-Critic-Identify neural network architecture. First, a dynamic model of the combined spacecraft is established, with all uncertainties treated as lumped disturbances. To improve transient performance and remove initial value constraints, a flexible prescribed performance function is designed, which accommodates input saturation and decouples settling time from both initial states and controller parameters. Subsequently, a steady-state performance optimized Identify weight adaptation law is employed for rapid and accurate estimation of the nonlinear lumped disturbances. For fuel optimization, a simplified Actor-Critic adaptation law is developed, eliminating the need for complex step-by-step derivations while ensuring weight convergence. The uniform ultimate boundedness of the closed-loop system is proven using Lyapunov theory. Numerical simulations and semi-physical experiments verify the proposed method’s advantages in both steady-state and transient performance, as well as its applicability to on-orbit implementation.
{"title":"Simplified optimal backstepping control for a spacecraft based on flexible prescribed performance with non-initial constraint","authors":"Zhen Li, Guohua Kang, Junfeng Wu, Jiaqi Wu, Chuanxiao Xu","doi":"10.1016/j.conengprac.2026.106786","DOIUrl":"10.1016/j.conengprac.2026.106786","url":null,"abstract":"<div><div>This paper addresses the position and attitude control of combined spacecraft in on-orbit servicing missions, taking into account model parameter uncertainties, unknown external disturbances, and fuel-optimal constraints. A novel flexible prescribed-performance optimal backstepping controller without initial constraints is proposed by incorporating an Actor-Critic-Identify neural network architecture. First, a dynamic model of the combined spacecraft is established, with all uncertainties treated as lumped disturbances. To improve transient performance and remove initial value constraints, a flexible prescribed performance function is designed, which accommodates input saturation and decouples settling time from both initial states and controller parameters. Subsequently, a steady-state performance optimized Identify weight adaptation law is employed for rapid and accurate estimation of the nonlinear lumped disturbances. For fuel optimization, a simplified Actor-Critic adaptation law is developed, eliminating the need for complex step-by-step derivations while ensuring weight convergence. The uniform ultimate boundedness of the closed-loop system is proven using Lyapunov theory. Numerical simulations and semi-physical experiments verify the proposed method’s advantages in both steady-state and transient performance, as well as its applicability to on-orbit implementation.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106786"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-13DOI: 10.1016/j.conengprac.2026.106760
Shuo Wang , Baorui Wang , Guoxiang Gu
This paper proposes rail-less trains, composed of electric buses which are coupled together. The dynamic model of the rail-less electric bus train (REBT) involves not only nonlinearities but also unknown and uncertain parameters, which pose significant challenges. To mitigate model nonlinearities and parameter uncertainties in practical REBT system, we develop centralized and distributed adaptive control laws based on high-order full actuation (HOFA) control. For developing the centralized adaptive control law, we propose a novel adaptive control method, integrating gamma-projection operators with sigma-modification in adaptive estimation. This method robustly constrains parameter estimates within the known set while suppressing drift and offering tradeoffs between the magnitudes of control signal and tracking performance. For developing the distributed adaptive control law, we propose a different adaptive control method, employing both autonomous and cooperative control actions and using again the gamma-projection. In addition, adaptive estimation is aided by an off-line least-squares (LS) algorithm that ensures the adaptive estimates to converge to the true system parameters under the persistent excitation condition, leading to asymptotic feedback linearization and global asymptotic stabilization. Disturbance rejection in the framework of -control is studied for the linearized REBT system. It is shown that the two proposed adaptive control laws ensure the -norm from the input disturbance to the output tracking errors for velocity and inter-EB-distance controls to be strictly smaller than any γ > 0, effectively suppressing energy bounded disturbances in the worst-case. The simulation study includes industrial-level simulators and validates the proposed adaptive control methods.
{"title":"Full actuation control for rail-less electric bus trains","authors":"Shuo Wang , Baorui Wang , Guoxiang Gu","doi":"10.1016/j.conengprac.2026.106760","DOIUrl":"10.1016/j.conengprac.2026.106760","url":null,"abstract":"<div><div>This paper proposes rail-less trains, composed of electric buses which are coupled together. The dynamic model of the rail-less electric bus train (REBT) involves not only nonlinearities but also unknown and uncertain parameters, which pose significant challenges. To mitigate model nonlinearities and parameter uncertainties in practical REBT system, we develop centralized and distributed adaptive control laws based on high-order full actuation (HOFA) control. For developing the centralized adaptive control law, we propose a novel adaptive control method, integrating gamma-projection operators with sigma-modification in adaptive estimation. This method robustly constrains parameter estimates within the known set while suppressing drift and offering tradeoffs between the magnitudes of control signal and tracking performance. For developing the distributed adaptive control law, we propose a different adaptive control method, employing both autonomous and cooperative control actions and using again the gamma-projection. In addition, adaptive estimation is aided by an off-line least-squares (LS) algorithm that ensures the adaptive estimates to converge to the true system parameters under the persistent excitation condition, leading to asymptotic feedback linearization and global asymptotic stabilization. Disturbance rejection in the framework of <span><math><msub><mi>H</mi><mi>∞</mi></msub></math></span>-control is studied for the linearized REBT system. It is shown that the two proposed adaptive control laws ensure the <span><math><msub><mi>H</mi><mi>∞</mi></msub></math></span>-norm from the input disturbance to the output tracking errors for velocity and inter-EB-distance controls to be strictly smaller than any <em>γ</em> > 0, effectively suppressing energy bounded disturbances in the worst-case. The simulation study includes industrial-level simulators and validates the proposed adaptive control methods.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106760"},"PeriodicalIF":4.6,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}