Pub Date : 2026-01-16DOI: 10.1016/j.conengprac.2026.106767
John Cortés-Romero , Horacio Coral-Enriquez , Brian Camilo Gómez-León , Hebertt Sira-Ramírez
Implementable applications are often compromised by signals that allow some algebraic representation. Those signals, namely disturbances, negatively affect the performance of control strategies, especially in high-performance contexts. Common issues with existing methods that try to estimate and compensate for those disturbances include complex dimensions, inflexibility, cumbersome design processes, and problems related to high-gain observers that effectively compensate for the disturbances considered in the scheme. This paper introduces a novel, structurally simple multi-observer scheme that leverages prior knowledge of disturbances. By incorporating internal models for each disturbance component, this strategy enhances design simplicity, increases flexibility by allowing the addition of new observers for emerging disturbances, and circumvents problems associated with high dimensions and high gain. Additionally, a novel solution is presented to address the estimation of periodic signals without including a high-dimension observer. The effectiveness of this approach is demonstrated through well-executed and convincing experimental results.
{"title":"Decoupled multi-observer design for disturbance estimation with low-order internal models","authors":"John Cortés-Romero , Horacio Coral-Enriquez , Brian Camilo Gómez-León , Hebertt Sira-Ramírez","doi":"10.1016/j.conengprac.2026.106767","DOIUrl":"10.1016/j.conengprac.2026.106767","url":null,"abstract":"<div><div>Implementable applications are often compromised by signals that allow some algebraic representation. Those signals, namely disturbances, negatively affect the performance of control strategies, especially in high-performance contexts. Common issues with existing methods that try to estimate and compensate for those disturbances include complex dimensions, inflexibility, cumbersome design processes, and problems related to high-gain observers that effectively compensate for the disturbances considered in the scheme. This paper introduces a novel, structurally simple multi-observer scheme that leverages prior knowledge of disturbances. By incorporating internal models for each disturbance component, this strategy enhances design simplicity, increases flexibility by allowing the addition of new observers for emerging disturbances, and circumvents problems associated with high dimensions and high gain. Additionally, a novel solution is presented to address the estimation of periodic signals without including a high-dimension observer. The effectiveness of this approach is demonstrated through well-executed and convincing experimental results.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106767"},"PeriodicalIF":4.6,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979886","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":"2026-01-16","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 : 2026-01-16DOI: 10.1016/j.conengprac.2026.106788
Mengmeng Liu , Yuqiang Wu
The article proposes a dynamic event-triggered adaptive neural network (NN) stabilization control strategy for uncertain nonholonomic systems with irregular output constraints. Unlike existing methods which require continuous constraint boundaries, the proposed approach considers output constraints that occur only during specific time intervals. The irregular output constraints are handled by introducing a novel shift function and incorporating barrier functions. The dynamic event-triggered mechanism employs an adjustable threshold to conserve communication resources. Meanwhile, the NN technique addresses the system uncertainties. Rigorous stability analysis confirms that all closed-loop system signals remain bounded and that the irregular output constraints are never violated throughout the control process. In addition, the Zeno behavior is successfully avoided. Finally, numerical simulations and experimental tests are conducted on a QBot2e mobile robot to validate the effectiveness of the proposed control approach.
{"title":"Dynamic event-triggered stabilization of irregular output-constrained nonholonomic systems with experimental verification","authors":"Mengmeng Liu , Yuqiang Wu","doi":"10.1016/j.conengprac.2026.106788","DOIUrl":"10.1016/j.conengprac.2026.106788","url":null,"abstract":"<div><div>The article proposes a dynamic event-triggered adaptive neural network (NN) stabilization control strategy for uncertain nonholonomic systems with irregular output constraints. Unlike existing methods which require continuous constraint boundaries, the proposed approach considers output constraints that occur only during specific time intervals. The irregular output constraints are handled by introducing a novel shift function and incorporating barrier functions. The dynamic event-triggered mechanism employs an adjustable threshold to conserve communication resources. Meanwhile, the NN technique addresses the system uncertainties. Rigorous stability analysis confirms that all closed-loop system signals remain bounded and that the irregular output constraints are never violated throughout the control process. In addition, the Zeno behavior is successfully avoided. Finally, numerical simulations and experimental tests are conducted on a QBot2e mobile robot to validate the effectiveness of the proposed control approach.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106788"},"PeriodicalIF":4.6,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979885","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 : 2026-01-15DOI: 10.1016/j.conengprac.2025.106725
Salvatore Pedone, Adriano Fagiolini
In this paper the robust trajectory tracking control problem for a quadrotor aircraft is addressed by utilizing the estimates from an Enhanced Extended State Observer (EESO). More specifically, first, the quadrotor dynamics is reformulated by decoupling the known linear terms from the unknown and nonlinear ones and by modeling the latter as new additional state variables. Secondly, by exploiting the information deriving from the output and input vectors, respectively, an EESO is derived allowing an asymptotic estimation of the state vector even when the rate of change of the unknown disturbances is fast and not negligible. Finally, on the basis of the EESO estimates, a robust trajectory tracking controller is designed, ensuring the asymptotic convergence of system state trajectories to the desired ones. The full asymptotic stability is demonstrated analytically. Simulation results on a quadrotor model through a high-fidelity low-altitude simulation environment are shown to illustrate the efficiency of the proposed method also with respect to existing solution (Extended State Observer based Control).
{"title":"Robust trajectory tracking control for quadrotors based on an enhanced extended state observer","authors":"Salvatore Pedone, Adriano Fagiolini","doi":"10.1016/j.conengprac.2025.106725","DOIUrl":"10.1016/j.conengprac.2025.106725","url":null,"abstract":"<div><div>In this paper the robust trajectory tracking control problem for a quadrotor aircraft is addressed by utilizing the estimates from an Enhanced Extended State Observer (EESO). More specifically, first, the quadrotor dynamics is reformulated by decoupling the known linear terms from the unknown and nonlinear ones and by modeling the latter as new additional state variables. Secondly, by exploiting the information deriving from the output and input vectors, respectively, an EESO is derived allowing an asymptotic estimation of the state vector even when the rate of change of the unknown disturbances is fast and not negligible. Finally, on the basis of the EESO estimates, a robust trajectory tracking controller is designed, ensuring the asymptotic convergence of system state trajectories to the desired ones. The full asymptotic stability is demonstrated analytically. Simulation results on a quadrotor model through a high-fidelity low-altitude simulation environment are shown to illustrate the efficiency of the proposed method also with respect to existing solution (Extended State Observer based Control).</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106725"},"PeriodicalIF":4.6,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979980","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 : 2026-01-15DOI: 10.1016/j.conengprac.2026.106777
Giacomo Galuppini , Enrico Creaco , Lalo Magni
Leakage reduction is an extremely important goal in the management of Water Distribution Networks (WDNs). Due to the dependence of leakage on pressure, Real Time Control (RTC) represents an effective tool to mitigate leakage by dynamically removing pressure excess as the users demand varies during the day. Cost-effectiveness of RTC can be improved by transforming part of the pressure excess into electric energy. This result can be achieved by means of Pump-as-Turbines (PATs). This paper proposes a novel RTC scheme able to simultaneously regulate pressure at multiple WDN nodes, and recover part of the excess energy, which can be sent directly to the main electrical grid. The control scheme is based on a Kalman Filter for joint state and disturbance estimation, a tracking Model Predictive Controller for multi-output regulation, and an Actuator Settings Optimiser to adjust the PAT settings. Thanks to its modular structure, the algorithm is scalable, flexible, and computationally cheap. The effectiveness of the proposed RTC scheme is demonstrated with several closed-loop simulations, carried out on a detailed, pressure-driven, unsteady flow model of an existing WDN. Moreover, the proposed algorithm can be directly applied to real WDNs, as it does not require any hydraulic model of the entire plant to be designed and tuned.
{"title":"Multi-Node real time control for pressure regulation and energy recovery in water distribution networks using Pump-as-Turbines","authors":"Giacomo Galuppini , Enrico Creaco , Lalo Magni","doi":"10.1016/j.conengprac.2026.106777","DOIUrl":"10.1016/j.conengprac.2026.106777","url":null,"abstract":"<div><div>Leakage reduction is an extremely important goal in the management of Water Distribution Networks (WDNs). Due to the dependence of leakage on pressure, Real Time Control (RTC) represents an effective tool to mitigate leakage by dynamically removing pressure excess as the users demand varies during the day. Cost-effectiveness of RTC can be improved by transforming part of the pressure excess into electric energy. This result can be achieved by means of Pump-as-Turbines (PATs). This paper proposes a novel RTC scheme able to simultaneously regulate pressure at multiple WDN nodes, and recover part of the excess energy, which can be sent directly to the main electrical grid. The control scheme is based on a Kalman Filter for joint state and disturbance estimation, a tracking Model Predictive Controller for multi-output regulation, and an Actuator Settings Optimiser to adjust the PAT settings. Thanks to its modular structure, the algorithm is scalable, flexible, and computationally cheap. The effectiveness of the proposed RTC scheme is demonstrated with several closed-loop simulations, carried out on a detailed, pressure-driven, unsteady flow model of an existing WDN. Moreover, the proposed algorithm can be directly applied to real WDNs, as it does not require any hydraulic model of the entire plant to be designed and tuned.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106777"},"PeriodicalIF":4.6,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979891","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}
Nonlinear Model Predictive Control (NMPC) demonstrates strong capability in handling complex constrained systems; however, its non-convex optimization nature results in high computational complexity that limits practical implementation in real-time control scenarios. To address this computational bottleneck, this paper proposes an efficient Fully Actuated Fast Model Predictive Control (FA-FMPC) method. This method leverages the fully actuated (FA) system approach to modify the open-loop characteristics of nonlinear systems exhibiting complex nonlinearity, strong coupling, or time-delay effects, thereby constructing a linear time-invariant closed-loop system with a freely configurable characteristic structure. Based on this linear time-invariant system, a Fast Model Predictive Control (Fast MPC) method is designed. When the system constraints are convex, the NMPC problem can be transformed into a convex MPC problem. To improve computational efficiency, the Alternating Direction Method of Multipliers (ADMM) is employed to decompose the global optimization problem into multiple subproblems and solve them through alternating iterations. Meanwhile, the Riccati solution of the Linear Quadratic Regulator (LQR) is utilized to optimize the primal variable update process in ADMM, and by precomputing matrix operation components, online matrix decomposition is avoided, significantly enhancing computational efficiency. To validate the effectiveness of the proposed method, simulation verification is conducted on an under-actuated robotic system and a Universal Robots UR5 manipulator simulated in ROS Noetic with Gazebo.
{"title":"Design of a fast model predictive controller based on the fully actuated system approach","authors":"Shijie Zhang , Yuebin Qiu , Mingzhe Hou , Xiang Wu , Hui Zhang , Jilong Wang","doi":"10.1016/j.conengprac.2026.106762","DOIUrl":"10.1016/j.conengprac.2026.106762","url":null,"abstract":"<div><div>Nonlinear Model Predictive Control (NMPC) demonstrates strong capability in handling complex constrained systems; however, its non-convex optimization nature results in high computational complexity that limits practical implementation in real-time control scenarios. To address this computational bottleneck, this paper proposes an efficient Fully Actuated Fast Model Predictive Control (FA-FMPC) method. This method leverages the fully actuated (FA) system approach to modify the open-loop characteristics of nonlinear systems exhibiting complex nonlinearity, strong coupling, or time-delay effects, thereby constructing a linear time-invariant closed-loop system with a freely configurable characteristic structure. Based on this linear time-invariant system, a Fast Model Predictive Control (Fast MPC) method is designed. When the system constraints are convex, the NMPC problem can be transformed into a convex MPC problem. To improve computational efficiency, the Alternating Direction Method of Multipliers (ADMM) is employed to decompose the global optimization problem into multiple subproblems and solve them through alternating iterations. Meanwhile, the Riccati solution of the Linear Quadratic Regulator (LQR) is utilized to optimize the primal variable update process in ADMM, and by precomputing matrix operation components, online matrix decomposition is avoided, significantly enhancing computational efficiency. To validate the effectiveness of the proposed method, simulation verification is conducted on an under-actuated robotic system and a Universal Robots UR5 manipulator simulated in ROS Noetic with Gazebo.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106762"},"PeriodicalIF":4.6,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979979","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 : 2026-01-15DOI: 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":"2026-01-15","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}
Pub 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":"2026-01-14","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 : 2026-01-13DOI: 10.1016/j.conengprac.2026.106766
Sen Yang , Xiaofeng Li , Yanan Li
Piezoelectric fast steering mirrors (PFSMs) are widely employed in beam pointing systems. However, achieving high-precision tracking of fast trajectories remains challenging due to biaxial cross-coupling and a limited input range. Based on a Hammerstein-structured PFSM model, this paper proposes a model predictive control (MPC) approach to decouple the multiple-input-multiple-output rate-dependent biaxial linear dynamics with system constraints, where the state vector is augmented with error integral variables to eliminate steady-state errors. Then an inverse hysteresis compensator is series-connected for the rate-independent nonlinearities. Furthermore, theoretical proofs of zero steady-state error and disturbance rejection for the proposed controller are provided. Tracking experiments on step, sinusoidal, and composite trajectories are conducted. Compared to proportional-integral-derivative model-free controller and various model-based approaches, including the direct inverse model feedforward, normalized least mean squares adaptive control, and adaptive sliding mode control, the proposed MPC achieves a 69% reduction in the root-mean-square error for 400Hz sinusoidal tracking relative to the baseline controllers, while also exhibiting robustness to frequency variations.
{"title":"Design of an MPC with hysteresis compensation for high-accuracy trajectory tracking of piezoelectric fast steering mirrors","authors":"Sen Yang , Xiaofeng Li , Yanan Li","doi":"10.1016/j.conengprac.2026.106766","DOIUrl":"10.1016/j.conengprac.2026.106766","url":null,"abstract":"<div><div>Piezoelectric fast steering mirrors (PFSMs) are widely employed in beam pointing systems. However, achieving high-precision tracking of fast trajectories remains challenging due to biaxial cross-coupling and a limited input range. Based on a Hammerstein-structured PFSM model, this paper proposes a model predictive control (MPC) approach to decouple the multiple-input-multiple-output rate-dependent biaxial linear dynamics with system constraints, where the state vector is augmented with error integral variables to eliminate steady-state errors. Then an inverse hysteresis compensator is series-connected for the rate-independent nonlinearities. Furthermore, theoretical proofs of zero steady-state error and disturbance rejection for the proposed controller are provided. Tracking experiments on step, sinusoidal, and composite trajectories are conducted. Compared to proportional-integral-derivative model-free controller and various model-based approaches, including the direct inverse model feedforward, normalized least mean squares adaptive control, and adaptive sliding mode control, the proposed MPC achieves a 69% reduction in the root-mean-square error for 400Hz sinusoidal tracking relative to the baseline controllers, while also exhibiting robustness to frequency variations.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106766"},"PeriodicalIF":4.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980020","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 : 2026-01-13DOI: 10.1016/j.conengprac.2026.106764
Sen Li , Qi Chen , Weihua Li , Mingfeng Wang , Sungsung Pang , Kai Wu
Robotic ultrasound systems can improve imaging consistency and reduce operator workload by maintaining stable probe–tissue contact forces. However, variations in tissue stiffness and surface position often degrade force-tracking performance. This paper presents a disturbance observer–based sliding mode admittance control (DOSMAC) framework to address these challenges. Stiffness and position variations are uniformly modeled as lumped external disturbances, estimated online by a disturbance observer and compensated through sliding mode control. The resulting signal is introduced as a virtual input to the admittance model, enhancing robustness without requiring online stiffness identification or extensive parameter tuning. The stability of the closed-loop system is established through Lyapunov analysis. Simulations and experiments with stiffness ranging from 500 to 3500 N/m verify the effectiveness of the proposed approach. In experiments with simultaneous stiffness and position variations, DOSMAC reduces overshoot by 29.1% and 55.4%, peak force error by 4.36 N and 0.46 N, and root mean square error by 1.79 N and 0.4 N, respectively, compared with conventional admittance control and adaptive variable admittance control. These results demonstrate that the proposed method enables stable and reliable force tracking under complex time-varying conditions, supporting the clinical translation forceof robotic ultrasound.
{"title":"Observer-based sliding mode admittance control for ultrasound robot force-tracking in complex interaction environments","authors":"Sen Li , Qi Chen , Weihua Li , Mingfeng Wang , Sungsung Pang , Kai Wu","doi":"10.1016/j.conengprac.2026.106764","DOIUrl":"10.1016/j.conengprac.2026.106764","url":null,"abstract":"<div><div>Robotic ultrasound systems can improve imaging consistency and reduce operator workload by maintaining stable probe–tissue contact forces. However, variations in tissue stiffness and surface position often degrade force-tracking performance. This paper presents a disturbance observer–based sliding mode admittance control (DOSMAC) framework to address these challenges. Stiffness and position variations are uniformly modeled as lumped external disturbances, estimated online by a disturbance observer and compensated through sliding mode control. The resulting signal is introduced as a virtual input to the admittance model, enhancing robustness without requiring online stiffness identification or extensive parameter tuning. The stability of the closed-loop system is established through Lyapunov analysis. Simulations and experiments with stiffness ranging from 500 to 3500 N/m verify the effectiveness of the proposed approach. In experiments with simultaneous stiffness and position variations, DOSMAC reduces overshoot by 29.1% and 55.4%, peak force error by 4.36 N and 0.46 N, and root mean square error by 1.79 N and 0.4 N, respectively, compared with conventional admittance control and adaptive variable admittance control. These results demonstrate that the proposed method enables stable and reliable force tracking under complex time-varying conditions, supporting the clinical translation forceof robotic ultrasound.</div></div>","PeriodicalId":50615,"journal":{"name":"Control Engineering Practice","volume":"169 ","pages":"Article 106764"},"PeriodicalIF":4.6,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980022","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}
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