Feedforward control is one of the most effective control techniques to increase the robot’s tracking accuracy.However,most of the dynamic models used in the feedforward controllers are linearly simplified such that t...Feedforward control is one of the most effective control techniques to increase the robot’s tracking accuracy.However,most of the dynamic models used in the feedforward controllers are linearly simplified such that the nonlinear and time-varying characteristics of dynamics in the workspace are ignored.In this paper,an iterative tuning method for feedforward control of parallel manipulators by taking nonlinear dynamics into account is proposed.Based on the robot rigid-body dynamic model,a feedforward controller considering the dynamic nonlinearity is presented.An iterative tuning method is given to iteratively update the feedforward controller by minimizing the root mean square(RMS)of the joint errors at each cycle.The effectiveness and extrapolation capability of the proposed method are validated through the experiments on a 2-DOF parallel manipulator.This research proposes an iterative tuning method for feedforward control of parallel manipulators considering nonlinear dynamics,which has better extrapolation capability in the whole workspace of manipulators.展开更多
Under the condition of large inertia load,the stability of the servo system is more sensitive to the response speed and more likely to produce overshoot oscillations.In order to realize the requirements of high-precis...Under the condition of large inertia load,the stability of the servo system is more sensitive to the response speed and more likely to produce overshoot oscillations.In order to realize the requirements of high-precision and fast-response control of permanent magnet synchronous motor(PMSM)under large inertia load,an improved feedforward control strategy based on position impulse compensation and PD iterative algorithm is proposed to improve the response speed of the PMSM servo system and reduce the overshoot oscillation.This paper analyzes the mathematical models of the speed servo system and position servo system of the PMSM,calculates position overshoot impulse of the PMSM servo system,and improves the traditional feedforward control strategy to reversely compensate when the position is about to overshoot.Moreover,in order to further reduce the position overshoot,the PD iterative control algorithm is superimposed without increasing the complexity of the algorithm.The input signal is continuously corrected through multiple runs to achieve a smoother response control.The effectiveness of the proposed feedforward control strategy is verified by simulation and experiment.展开更多
This paper,evaluate the effectiveness of a proposed speed loop pseudo derivative feedforward(PDFF)controller-based direct torque controller(DTC)for a PMSM drive against the performance of existing PI speed controller-...This paper,evaluate the effectiveness of a proposed speed loop pseudo derivative feedforward(PDFF)controller-based direct torque controller(DTC)for a PMSM drive against the performance of existing PI speed controller-based DTC and hysteresis current controller(HCC).The proposed PDFF-based speed regulator effectively reduces oscillation and overshoot associated with rotor angular speed,electromagnetic torque,and stator current.Two case studies,one using forward-to-reverse motoring operation and the other involving reverse-to-forward braking operation,has been validated to show the effectiveness of the proposed control strategy.The proposed controller's superior performance is demonstrated through experimental verification utilizing an FPGA controller for a 1.5 kW PMSM drive laboratory prototype.展开更多
Objective:To analyze the application effect of feedforward control in outpatient blood specimen management.Methods:1,200 patients who had their venous blood collected in outpatient phlebotomy room of our hospital'...Objective:To analyze the application effect of feedforward control in outpatient blood specimen management.Methods:1,200 patients who had their venous blood collected in outpatient phlebotomy room of our hospital's outpatient clinic from January 2021 to April 2021 were selected as study subjects and divided into 600 cases in the control group and 600 cases in the observation group.The two groups of patients were compared in terms of their satisfaction with the staff,the efficiency of the nurses and the quality of nursing care,turnaround time before specimen analysis,the rejection rate of the blood specimens,and the time of result reporting.Results:After the implementation of feedforward control,patients'satisfaction with staff,nurses work efficiency and quality of care,turnaround time before specimen analysis,specimen rejection rate,and result reporting time in the observation group were significantly higher than those in the control group(P<0.05).Conclusion:The application of feedforward control in the management of outpatient blood specimens has significant effect,which effectively improves patients'satisfaction,enhances the efficiency of nurses and the quality of nursing care,shortens the turnaround time of specimens before analysis and the reporting time of results,and reduces the rejection rate of specimens.展开更多
Parallel manipulators with less than six degrees of freedom （DOF） have been increasingly used in high-speed hybrid machine tools. The structural features of parallel manipulators are dynamic, a characteristic that i...Parallel manipulators with less than six degrees of freedom （DOF） have been increasingly used in high-speed hybrid machine tools. The structural features of parallel manipulators are dynamic, a characteristic that is particularly significant when these manipulators are used in high-speed machine tools. However, normal kinematic control method cannot satisfy the requirements of the control system. Many researchers use model-based dynamic control methods, such as the dynamic feedforward control method. However, these methods are rarely used in hybrid machine tools because of the complex dynamic model of the parallel manipulator. In order to study the dynamic control method of parallel manipulators, the dynamic feedforward control method is used in the dynamic control system of a 3-PSP （prismatic-spherical-prismatic） 3-DOF spatial parallel manipulator used as a spindle head in a high-speed hybrid machine tool. Using kinematic analysis as basis and the Newton-Euler method, we derive the dynamic model of the parallel manipulator. Furthermore, a model-based dynamic feedforward control system consisting of both kinematic control and dynamic control subsystems is established. The dynamic control subsystem consists of two modules. One is used to eliminate the influence of the dynamic characteristics of high-speed movement, and the other is used to eliminate the dynamic disturbances in the milling process. Finally, the simulation model of the dynamic feedforward control system of the 3-PSP parallel manipulator is constructed in Matlab/Simulink. The simulations of the control system eliminating the influence of the dynamic characteristics and dynamic disturbances are conducted. A comparative study between the simulations and the normal kinematic control method is also presented.The simulations prove that the dynamic feedforward control method effectively eliminates the influence of the dynamic disturbances and dynamic characteristics of the parallel manipulator on high-speed machine tools, and significantly improves the trajectory accuracy. This is the first attempt to introduce the dynamic feedfordward control method into the 3-PSP spatial parallel manipulator whose dynamic model is complex and provides a study basis for the real-time dynamic control of the high-speed hybrid machine tools.展开更多
A gain-scheduled feedforward controller, based on pseudo-LIDAR （light detection and ranging） wind speed measurement, is designed to augment the baseline feedback controller for wind turbine＇s load reduction in abov...A gain-scheduled feedforward controller, based on pseudo-LIDAR （light detection and ranging） wind speed measurement, is designed to augment the baseline feedback controller for wind turbine＇s load reduction in above rated operation. The pseudo-LIDAR measurement data are generated from a commercial software- Bladed using a designed sampling strategy. The nonlinear wind turbine model has been simplified and linearised at a set of equilibrium operating points. The feedforward controller is firstly developed based on a linearised model at an above rated wind speed, and then expanded to the full above rated operational envelope by employing gain scheduling strategy. The combined feedforward and baseline feedback control is simulated on a 5MW industrial wind turbine model. Simulation studies demonstrate that the proposed control strategy can improve the rotor and tower load reduction performance for large wind turbines.展开更多
Objective:To explore the application of feedforward control in the nursing emergency management of COVID-19.Methods:The feedforward control theory was applied to the emergency management of COVID-19 nursing,including ...Objective:To explore the application of feedforward control in the nursing emergency management of COVID-19.Methods:The feedforward control theory was applied to the emergency management of COVID-19 nursing,including grasping the latest epidemic information,preparing for the early stage,formulating nursing workflow,implementing flexible management,standardizing isolation and protection measures,unifying nursing document record format,and implementing humanistic care.Results:During the period of support to Wuhan,the nursing work in the isolated area was orderly,the nursing staff's job satisfaction was high,no nursing errors and hospital infections occurred.Conclusion:Efficient feedforward control in the nursing emergency management that could avoid work blindness to a certain extent and play a guiding role in maintaining the normal operation of treatment and nursing work and protecting the safety of patients and medical staff in the ward during the epidemic period of COVID-19.展开更多
Objective: to explore the application effect of feedforward control in nursing safety management in operating room. Methods: 70 cases of surgical patients admitted to our hospital were selected for research, and the s...Objective: to explore the application effect of feedforward control in nursing safety management in operating room. Methods: 70 cases of surgical patients admitted to our hospital were selected for research, and the selected time was from January 2020 to December 2021. The patients were randomly divided into the observation group and the control group with 35 cases in each group. The patients in the control group were given routine management, while the patients in the observation group were given feedforward management. The application effects of the two management methods were compared and observed. Results: the scores of nursing service attitude, implementation of rules and regulations, nursing quality ability and quality control examination in the observation group were (14.56±2.16), (13.45±1.72), (94.89±3.26) and (95.68±3.60) respectively, and the difference was statistically significant (p < 0.05) when compared with the control group. In the observation group, the patients' satisfaction with nursing was 97.14%, and the incidence of nursing risk events was 5.71%. Compared with the control group, the difference was statistically significant (P < 0.05). Conclusion: the application of feedforward control management measures in the nursing safety management of operating room can improve the nursing safety management level, reduce the occurrence of nursing safety incidents, achieve patient satisfaction, ease the relationship between nurses and patients, and has good clinical popularization.展开更多
Three feedforward (FFD) control techniques for position-servo machine axesare compared. All three FFD controllers are used with two different PID feedback (FBK) controllers.The two different FBK controllers have two d...Three feedforward (FFD) control techniques for position-servo machine axesare compared. All three FFD controllers are used with two different PID feedback (FBK) controllers.The two different FBK controllers have two different closed-loop bandwidths. They are demonstratedusing experimental data from a linear motor test system and from simulations. Laboratory resultsusing the linear motor hardware demonstrate that the velocity & acceleration (V&A) FFD controllerimproves tracking in all case considered, while the other two FFD controllers actually degradeperformance in many cases. Through simulation this degradation is attributed to extreme sensitivityto round off errors. This sensitivity is the result of a complex controller that is implementedoutside of the feedback loop.展开更多
A feedforward controller for the automatic regulation of chemical composition of molten steel in the tundish of a continuous casting machine is proposed in this work. The flow of molten steel inside the tundish is mod...A feedforward controller for the automatic regulation of chemical composition of molten steel in the tundish of a continuous casting machine is proposed in this work. The flow of molten steel inside the tundish is modeled as a distributed parameter system, and the resulting partial differential equation is transformed into a set of ordinary differential equations by means of the finite differences technique. From the above set and using a proper boundary condition, a feedforward control law is synthesized. No experimental tests are reported, however, the dynamic performance of the controller is illustrated by means of numerical simulations.展开更多
The acquisition,tracking,and pointing(ATP)system is widely used in target tracking,counter-UAV operations,and other related fields.As UAV technology develops,there is a growing demand to enhance the tracking capabilit...The acquisition,tracking,and pointing(ATP)system is widely used in target tracking,counter-UAV operations,and other related fields.As UAV technology develops,there is a growing demand to enhance the tracking capabilities of ATP systems.However,in practical applications,ATP systems face various design constraints and functional limitations,making it infeasible to indefinitely improve hardware performance to meet tracking requirements.As a result,tracking algorithms are required to execute increasingly complex tasks.This study introduces a multi-rate feedforward predictive controller to address issues such as low image feedback frequency and significant delays in ATP systems,which lead to tracking jitter,poor tracking performance,low precision,and target loss.At the same time,the pro-posed approach aims to improve the tracking capabilities of ATP systems for high-speed and highly maneuverable targets under conditions of low sampling feedback rates and high feedback delays.The method suggested is also characterized by its low order,fast response,and robustness to model parameter variations.In this study,an actual ATP system is built for target tracking test,and the proposed algorithm is fully validated in terms of simulation and actual system application verification.Results from both simulations and experiments demonstrate that the method effectively compensates for delays and low sampling rates.For targets with relative angular velocities ranging from 0 to 90°/s and angular accelerations between 0 and 470°/s^(2),the system improved tracking accuracy by 70.0%-89.9%at a sampling frequency of 50 Hz and a delay of 30 m s.Moreover,the compensation algorithm demonstrated consistent performance across actuators with varying characteristics,further confirming its robustness to model insensitivity.In summary,the proposed algorithm considerably enhances the tracking accuracy and capability of ATP systems for high-speed and highly maneuverable targets,reducing the probability of target loss from high speed.This approach offers a practical solution for future multi-target tracking across diverse operational scenarios.展开更多
To enhance the tip positioning accuracy and robustness against disturbances of linear colocated motion systems,a novel composite feedforward(COMFF)control with Bi-Loop iterative feedforward tuning(IFFT)is proposed.The...To enhance the tip positioning accuracy and robustness against disturbances of linear colocated motion systems,a novel composite feedforward(COMFF)control with Bi-Loop iterative feedforward tuning(IFFT)is proposed.The tip positioning error consists of the coupled tip residual vibration and linear motor tracking error.Given the influence of nonlinear friction and load flexibility,the topology of COMFF is designed as decoupled structures so that COMFF can suppress the tip residual vibration and compensate for the linear motor tracking error compatibly.Furthermore,Bi-Loop IFFT is built to improve the robustness of COMFF in high-precision motor tracking performance.In the state space of the linear motor tracking error based on the projection theorem,two loops are performed in parallel along the iteration direction.One is the P-type iteration loop that drives linear motor tracking errors to converge to the zero state.The other is the observation loop constructed by the recursive least square with forgetting factors to accelerate the P-type iteration loop.Driven by the P-type iteration loop with the aid of the observation loop,the proposed COMFF is integrated with fast convergence and high robustness when confronted with model disturbances.The effectiveness of the proposed COMFF combined with Bi-Loop IFFT is validated by experiments.展开更多
The optimal control is investigated for linear systems affected by external harmonic disturbance and applied to vibration control systems of offshore steel jacket platforms. The wave-induced force is the dominant load...The optimal control is investigated for linear systems affected by external harmonic disturbance and applied to vibration control systems of offshore steel jacket platforms. The wave-induced force is the dominant load that offshore structures are subjected to, and it can be taken as harmonic excitation for the system. The linearized Morison equation is employed to estimate the wave loading. The main result concerns the existence and design of a realizable optimal regulator, which is proposed to damp the forced oscillation in an optimal fashion. For demonstration of the effectiveness of the control scheme, the platform performance is investigated for different wave states. The simulations are based on the tuned mass damper and the active mass damper control devices. It is demonstrated that the control scheme is useful in reducing the displacement response of jacket-type offshore platforms.展开更多
Feedforward control based on an accurate dynamic model is an effective approach to reduce the dynamic effect of the robot and improve its performance. However, due to the complicated work environment with considerable...Feedforward control based on an accurate dynamic model is an effective approach to reduce the dynamic effect of the robot and improve its performance. However, due to the complicated work environment with considerable uncertainty, it is difficult to obtain a high-precision dynamic model of the robot, which severely deteriorates the achievable control performance. This paper proposes an iterative learning method to accurately design the industrial feedforward controller and compensate for the external uncertain dynamic load of the robot. Based on a standard dynamic model, a complete linear feedforward controller is presented.An iterative design strategy is given to iteratively update the feedforward controller by combining the Moore-Penrose Inverse and the PID learning rate. Experiments are carried out on a 5-DOF industrial hybrid robot to validate the effectiveness of the proposed iterative learning method. The experiment results illustrate that the industrial feedforward controller can rapidly converge to the optimal controller and significantly improve the servo performance by using the proposed method. This paper provides an effective method for applying iterative learning control to an unopened industrial control system. It is very useful for the practical control of hybrid robots in industrial field.展开更多
Underwater gliders are highly efficient,buoyancy-driven,and winged autonomous underwater vehicles.Their dynamics are multivariable nonlinear systems with unstable internal dynamics and thus their motion control is a s...Underwater gliders are highly efficient,buoyancy-driven,and winged autonomous underwater vehicles.Their dynamics are multivariable nonlinear systems with unstable internal dynamics and thus their motion control is a significant challenge.To improve the inherent efficiency and enhance the behavior of the underwater glider over a wide operating regime,a nonlinear feedforward and feedback controller was developed.The nonlinear feedforward control design is based on a new stable inversion technique which determines a causal and bounded solution for the unstable internal dynamics.The feedback control law was designed by a quadratic optimal control method.Simulation results show that the derived control system is able to deal with nonminimum phase system and successfully achieves the tracking of planned output trajectories from initial to final conditions.Furthermore,the control effort is very low,which means the glider with limited power storage has longer range and higher endurance.展开更多
Automatic gauge control is an essentially nonlinear process varying with time delay,and stochastically varying input and process noise always influence the target gauge control accuracy.To improve the control capabili...Automatic gauge control is an essentially nonlinear process varying with time delay,and stochastically varying input and process noise always influence the target gauge control accuracy.To improve the control capability of feedforward automatic gauge control,Kalman filter was employed to filter the noise signal transferred from one stand to another.The linearized matrix that the Kalman filter algorithm needed was concluded;thus,the feedforward automatic gauge control architecture was dynamically optimized.The theoretical analyses and simulation show that the proposed algorithm is reasonable and effective.展开更多
To improve the efficiency of nitrogen removalwith lower energy consumption,the study of feedforwardcontrol was carried out on a pilot-scale anaerobic-anoxicoxic(AAO)plant for the treatment of municipal wastewater.The ...To improve the efficiency of nitrogen removalwith lower energy consumption,the study of feedforwardcontrol was carried out on a pilot-scale anaerobic-anoxicoxic(AAO)plant for the treatment of municipal wastewater.The effluent qualities of the pilot plant underdifferent control strategies were investigated.The resultsindicated that the change of external recycle was not asuitable approach to regulate the sludge concentration ofplug-flow reactors;adjusting the aeration valve anddissolved oxygen set-point according to ammonia loadcould overcome the impact of influent fluctuation;and thedenitrification potential could be estimated based on thetransit time of anoxic zone and the relative content ofcarbon resource entering the anoxic zone.Simple feedforwardcontrol strategies for aeration and internal recyclewere subsequently proposed and validated.The nitrogenremoval was successfully improved in the pilot plant.Theeffluent total nitrogen had decreased by 29.9%and wassteadily controlled below 15 mg·L^(-1).Furthermore,approximately 38%of the energy for aeration had beensaved.展开更多
The optimal control problem for linear time-varying systems affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions is consider and a design procedure of a feedfo...The optimal control problem for linear time-varying systems affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions is consider and a design procedure of a feedforward and feedbaek optimal controller is presented. The condition of existence and uniqueness of the control law is given. The disturbanee observer is proposed to make the feedforward control law realizable physically. Simulation results demonstrate that the feedforward and feedbaek optimal control law is more effective and robust than the elassical state feedbaek control law with respect to external disturbanees.展开更多
This paper proposes a neural network-based intelligent feedforward gust alleviation framework,which includes a neural network identification model and a neural network controller.A neural network training dataset is f...This paper proposes a neural network-based intelligent feedforward gust alleviation framework,which includes a neural network identification model and a neural network controller.A neural network training dataset is formed by collecting flight data and the gust data encountered during the aircraft flight.A neural network identification model is first trained to accurately predict the aircraft’s output.Then,based on the output of the identification model and the collected flight data,the parameters of the time-delay neural network controller are obtained through a learning process.The simulation results show that the designed intelligent controller has good gust alleviation effects for both continuous turbulence excitation and discrete gust excitation.For example,when the aircraft is 40000 kg and the flight speed is 0.81Ma,the controller achieves a 67.82%reduction in wingtip acceleration and a 35.90%reduction in center of mass acceleration under continuous turbulence excitation.When considering the measurement uncertainties,such as noise existing in the collected data,the trained controller can still achieve an acceptable gust alleviation effect.Finally,considering a flight in which the aircraft mass is constantly changing,the intelligent controller,which continuously learns from new flight data,maintains a good gust alleviation effect throughout the flight.展开更多
A three-dimensional （3-D） physiological articulatory model was developed to account for the biomechanical properties of the speech organs in speech production. Control of the model to investigate the mechanism of sp...A three-dimensional （3-D） physiological articulatory model was developed to account for the biomechanical properties of the speech organs in speech production. Control of the model to investigate the mechanism of speech production requires an efficient control module to estimate muscle activation patterns, which is used to manipulate the 3-D physiological articulatory model, according to the desired articulatory posture. For this purpose, a feedforward control strategy was developed by mapping the articulatory target to the corresponding muscle activation pattern via the intrinsic representation of vowel articulation. In this process, the articulatory postures are first mapped to the corresponding intrinsic representations; then, the articulatory postures are clustered in the intrinsic representations space and a nonlinear function is approximated for each cluster to map the intrinsic representation of vowel articulation to the muscle activation pattern by using general regression neural networks （GRNN）. The results show that the feedforward control module is able to manipulate the 3-D physiological articulatory model for vowel production with high accuracy both acoustically and articulatorily.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52375502)EU H2020 MSCA R&I Programme(Grant No.101022696).
文摘Feedforward control is one of the most effective control techniques to increase the robot’s tracking accuracy.However,most of the dynamic models used in the feedforward controllers are linearly simplified such that the nonlinear and time-varying characteristics of dynamics in the workspace are ignored.In this paper,an iterative tuning method for feedforward control of parallel manipulators by taking nonlinear dynamics into account is proposed.Based on the robot rigid-body dynamic model,a feedforward controller considering the dynamic nonlinearity is presented.An iterative tuning method is given to iteratively update the feedforward controller by minimizing the root mean square(RMS)of the joint errors at each cycle.The effectiveness and extrapolation capability of the proposed method are validated through the experiments on a 2-DOF parallel manipulator.This research proposes an iterative tuning method for feedforward control of parallel manipulators considering nonlinear dynamics,which has better extrapolation capability in the whole workspace of manipulators.
基金supported in part by the National Natural Science Foundation of China under Project No.52207043。
文摘Under the condition of large inertia load,the stability of the servo system is more sensitive to the response speed and more likely to produce overshoot oscillations.In order to realize the requirements of high-precision and fast-response control of permanent magnet synchronous motor(PMSM)under large inertia load,an improved feedforward control strategy based on position impulse compensation and PD iterative algorithm is proposed to improve the response speed of the PMSM servo system and reduce the overshoot oscillation.This paper analyzes the mathematical models of the speed servo system and position servo system of the PMSM,calculates position overshoot impulse of the PMSM servo system,and improves the traditional feedforward control strategy to reversely compensate when the position is about to overshoot.Moreover,in order to further reduce the position overshoot,the PD iterative control algorithm is superimposed without increasing the complexity of the algorithm.The input signal is continuously corrected through multiple runs to achieve a smoother response control.The effectiveness of the proposed feedforward control strategy is verified by simulation and experiment.
基金supported by Prince Sultan University,Riyadh,Saudi Arabia,under research grant SEED-2022-CE-95。
文摘This paper,evaluate the effectiveness of a proposed speed loop pseudo derivative feedforward(PDFF)controller-based direct torque controller(DTC)for a PMSM drive against the performance of existing PI speed controller-based DTC and hysteresis current controller(HCC).The proposed PDFF-based speed regulator effectively reduces oscillation and overshoot associated with rotor angular speed,electromagnetic torque,and stator current.Two case studies,one using forward-to-reverse motoring operation and the other involving reverse-to-forward braking operation,has been validated to show the effectiveness of the proposed control strategy.The proposed controller's superior performance is demonstrated through experimental verification utilizing an FPGA controller for a 1.5 kW PMSM drive laboratory prototype.
文摘Objective:To analyze the application effect of feedforward control in outpatient blood specimen management.Methods:1,200 patients who had their venous blood collected in outpatient phlebotomy room of our hospital's outpatient clinic from January 2021 to April 2021 were selected as study subjects and divided into 600 cases in the control group and 600 cases in the observation group.The two groups of patients were compared in terms of their satisfaction with the staff,the efficiency of the nurses and the quality of nursing care,turnaround time before specimen analysis,the rejection rate of the blood specimens,and the time of result reporting.Results:After the implementation of feedforward control,patients'satisfaction with staff,nurses work efficiency and quality of care,turnaround time before specimen analysis,specimen rejection rate,and result reporting time in the observation group were significantly higher than those in the control group(P<0.05).Conclusion:The application of feedforward control in the management of outpatient blood specimens has significant effect,which effectively improves patients'satisfaction,enhances the efficiency of nurses and the quality of nursing care,shortens the turnaround time of specimens before analysis and the reporting time of results,and reduces the rejection rate of specimens.
基金supported by National Hi-tech Research and Development Program of China(863 Program, Grant No. 2007AA041901)National S&T Major Project of China(Grant No. 2009ZX04014-035)National Basic Research Program of China (973 Program, Grant No. 2006CB705400)
文摘Parallel manipulators with less than six degrees of freedom （DOF） have been increasingly used in high-speed hybrid machine tools. The structural features of parallel manipulators are dynamic, a characteristic that is particularly significant when these manipulators are used in high-speed machine tools. However, normal kinematic control method cannot satisfy the requirements of the control system. Many researchers use model-based dynamic control methods, such as the dynamic feedforward control method. However, these methods are rarely used in hybrid machine tools because of the complex dynamic model of the parallel manipulator. In order to study the dynamic control method of parallel manipulators, the dynamic feedforward control method is used in the dynamic control system of a 3-PSP （prismatic-spherical-prismatic） 3-DOF spatial parallel manipulator used as a spindle head in a high-speed hybrid machine tool. Using kinematic analysis as basis and the Newton-Euler method, we derive the dynamic model of the parallel manipulator. Furthermore, a model-based dynamic feedforward control system consisting of both kinematic control and dynamic control subsystems is established. The dynamic control subsystem consists of two modules. One is used to eliminate the influence of the dynamic characteristics of high-speed movement, and the other is used to eliminate the dynamic disturbances in the milling process. Finally, the simulation model of the dynamic feedforward control system of the 3-PSP parallel manipulator is constructed in Matlab/Simulink. The simulations of the control system eliminating the influence of the dynamic characteristics and dynamic disturbances are conducted. A comparative study between the simulations and the normal kinematic control method is also presented.The simulations prove that the dynamic feedforward control method effectively eliminates the influence of the dynamic disturbances and dynamic characteristics of the parallel manipulator on high-speed machine tools, and significantly improves the trajectory accuracy. This is the first attempt to introduce the dynamic feedfordward control method into the 3-PSP spatial parallel manipulator whose dynamic model is complex and provides a study basis for the real-time dynamic control of the high-speed hybrid machine tools.
基金supported by UK Engineering and Physical Sciences Research Council(EPSRC)Supergen Wind project(No.EP/N006224/1)
文摘A gain-scheduled feedforward controller, based on pseudo-LIDAR （light detection and ranging） wind speed measurement, is designed to augment the baseline feedback controller for wind turbine＇s load reduction in above rated operation. The pseudo-LIDAR measurement data are generated from a commercial software- Bladed using a designed sampling strategy. The nonlinear wind turbine model has been simplified and linearised at a set of equilibrium operating points. The feedforward controller is firstly developed based on a linearised model at an above rated wind speed, and then expanded to the full above rated operational envelope by employing gain scheduling strategy. The combined feedforward and baseline feedback control is simulated on a 5MW industrial wind turbine model. Simulation studies demonstrate that the proposed control strategy can improve the rotor and tower load reduction performance for large wind turbines.
基金We would like to thank Peng‑Zhi ZHANG and Xue‑Song WANG for their assistance in nursing workflow sorting.
文摘Objective:To explore the application of feedforward control in the nursing emergency management of COVID-19.Methods:The feedforward control theory was applied to the emergency management of COVID-19 nursing,including grasping the latest epidemic information,preparing for the early stage,formulating nursing workflow,implementing flexible management,standardizing isolation and protection measures,unifying nursing document record format,and implementing humanistic care.Results:During the period of support to Wuhan,the nursing work in the isolated area was orderly,the nursing staff's job satisfaction was high,no nursing errors and hospital infections occurred.Conclusion:Efficient feedforward control in the nursing emergency management that could avoid work blindness to a certain extent and play a guiding role in maintaining the normal operation of treatment and nursing work and protecting the safety of patients and medical staff in the ward during the epidemic period of COVID-19.
文摘Objective: to explore the application effect of feedforward control in nursing safety management in operating room. Methods: 70 cases of surgical patients admitted to our hospital were selected for research, and the selected time was from January 2020 to December 2021. The patients were randomly divided into the observation group and the control group with 35 cases in each group. The patients in the control group were given routine management, while the patients in the observation group were given feedforward management. The application effects of the two management methods were compared and observed. Results: the scores of nursing service attitude, implementation of rules and regulations, nursing quality ability and quality control examination in the observation group were (14.56±2.16), (13.45±1.72), (94.89±3.26) and (95.68±3.60) respectively, and the difference was statistically significant (p < 0.05) when compared with the control group. In the observation group, the patients' satisfaction with nursing was 97.14%, and the incidence of nursing risk events was 5.71%. Compared with the control group, the difference was statistically significant (P < 0.05). Conclusion: the application of feedforward control management measures in the nursing safety management of operating room can improve the nursing safety management level, reduce the occurrence of nursing safety incidents, achieve patient satisfaction, ease the relationship between nurses and patients, and has good clinical popularization.
基金This project is supported by United State's National Science Foundation (No.997761).
文摘Three feedforward (FFD) control techniques for position-servo machine axesare compared. All three FFD controllers are used with two different PID feedback (FBK) controllers.The two different FBK controllers have two different closed-loop bandwidths. They are demonstratedusing experimental data from a linear motor test system and from simulations. Laboratory resultsusing the linear motor hardware demonstrate that the velocity & acceleration (V&A) FFD controllerimproves tracking in all case considered, while the other two FFD controllers actually degradeperformance in many cases. Through simulation this degradation is attributed to extreme sensitivityto round off errors. This sensitivity is the result of a complex controller that is implementedoutside of the feedback loop.
文摘A feedforward controller for the automatic regulation of chemical composition of molten steel in the tundish of a continuous casting machine is proposed in this work. The flow of molten steel inside the tundish is modeled as a distributed parameter system, and the resulting partial differential equation is transformed into a set of ordinary differential equations by means of the finite differences technique. From the above set and using a proper boundary condition, a feedforward control law is synthesized. No experimental tests are reported, however, the dynamic performance of the controller is illustrated by means of numerical simulations.
基金supported by the National Natural Science Foun-dation of China(Grant No.52275099).
文摘The acquisition,tracking,and pointing(ATP)system is widely used in target tracking,counter-UAV operations,and other related fields.As UAV technology develops,there is a growing demand to enhance the tracking capabilities of ATP systems.However,in practical applications,ATP systems face various design constraints and functional limitations,making it infeasible to indefinitely improve hardware performance to meet tracking requirements.As a result,tracking algorithms are required to execute increasingly complex tasks.This study introduces a multi-rate feedforward predictive controller to address issues such as low image feedback frequency and significant delays in ATP systems,which lead to tracking jitter,poor tracking performance,low precision,and target loss.At the same time,the pro-posed approach aims to improve the tracking capabilities of ATP systems for high-speed and highly maneuverable targets under conditions of low sampling feedback rates and high feedback delays.The method suggested is also characterized by its low order,fast response,and robustness to model parameter variations.In this study,an actual ATP system is built for target tracking test,and the proposed algorithm is fully validated in terms of simulation and actual system application verification.Results from both simulations and experiments demonstrate that the method effectively compensates for delays and low sampling rates.For targets with relative angular velocities ranging from 0 to 90°/s and angular accelerations between 0 and 470°/s^(2),the system improved tracking accuracy by 70.0%-89.9%at a sampling frequency of 50 Hz and a delay of 30 m s.Moreover,the compensation algorithm demonstrated consistent performance across actuators with varying characteristics,further confirming its robustness to model insensitivity.In summary,the proposed algorithm considerably enhances the tracking accuracy and capability of ATP systems for high-speed and highly maneuverable targets,reducing the probability of target loss from high speed.This approach offers a practical solution for future multi-target tracking across diverse operational scenarios.
基金supported by the National Natural Science Foundation Regional Innovation and Development Joint Fund Integrated Project(Grant No.U23A6017)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(Grant No.226Z1805G).
文摘To enhance the tip positioning accuracy and robustness against disturbances of linear colocated motion systems,a novel composite feedforward(COMFF)control with Bi-Loop iterative feedforward tuning(IFFT)is proposed.The tip positioning error consists of the coupled tip residual vibration and linear motor tracking error.Given the influence of nonlinear friction and load flexibility,the topology of COMFF is designed as decoupled structures so that COMFF can suppress the tip residual vibration and compensate for the linear motor tracking error compatibly.Furthermore,Bi-Loop IFFT is built to improve the robustness of COMFF in high-precision motor tracking performance.In the state space of the linear motor tracking error based on the projection theorem,two loops are performed in parallel along the iteration direction.One is the P-type iteration loop that drives linear motor tracking errors to converge to the zero state.The other is the observation loop constructed by the recursive least square with forgetting factors to accelerate the P-type iteration loop.Driven by the P-type iteration loop with the aid of the observation loop,the proposed COMFF is integrated with fast convergence and high robustness when confronted with model disturbances.The effectiveness of the proposed COMFF combined with Bi-Loop IFFT is validated by experiments.
文摘The optimal control is investigated for linear systems affected by external harmonic disturbance and applied to vibration control systems of offshore steel jacket platforms. The wave-induced force is the dominant load that offshore structures are subjected to, and it can be taken as harmonic excitation for the system. The linearized Morison equation is employed to estimate the wave loading. The main result concerns the existence and design of a realizable optimal regulator, which is proposed to damp the forced oscillation in an optimal fashion. For demonstration of the effectiveness of the control scheme, the platform performance is investigated for different wave states. The simulations are based on the tuned mass damper and the active mass damper control devices. It is demonstrated that the control scheme is useful in reducing the displacement response of jacket-type offshore platforms.
基金the National Key Research and Development Program of China(Grant No.2017YFE0111300)EU H2020-MSCA-RISEECSASDPE(Grant No.734272)the National Natural Science Foundation of China(Grant No.51975321)。
文摘Feedforward control based on an accurate dynamic model is an effective approach to reduce the dynamic effect of the robot and improve its performance. However, due to the complicated work environment with considerable uncertainty, it is difficult to obtain a high-precision dynamic model of the robot, which severely deteriorates the achievable control performance. This paper proposes an iterative learning method to accurately design the industrial feedforward controller and compensate for the external uncertain dynamic load of the robot. Based on a standard dynamic model, a complete linear feedforward controller is presented.An iterative design strategy is given to iteratively update the feedforward controller by combining the Moore-Penrose Inverse and the PID learning rate. Experiments are carried out on a 5-DOF industrial hybrid robot to validate the effectiveness of the proposed iterative learning method. The experiment results illustrate that the industrial feedforward controller can rapidly converge to the optimal controller and significantly improve the servo performance by using the proposed method. This paper provides an effective method for applying iterative learning control to an unopened industrial control system. It is very useful for the practical control of hybrid robots in industrial field.
基金the National Natural Science Foundation of China(No. 50979058)the Special Research Fund for the Doctoral Program of Higher Education(No. 20090073110012)
文摘Underwater gliders are highly efficient,buoyancy-driven,and winged autonomous underwater vehicles.Their dynamics are multivariable nonlinear systems with unstable internal dynamics and thus their motion control is a significant challenge.To improve the inherent efficiency and enhance the behavior of the underwater glider over a wide operating regime,a nonlinear feedforward and feedback controller was developed.The nonlinear feedforward control design is based on a new stable inversion technique which determines a causal and bounded solution for the unstable internal dynamics.The feedback control law was designed by a quadratic optimal control method.Simulation results show that the derived control system is able to deal with nonminimum phase system and successfully achieves the tracking of planned output trajectories from initial to final conditions.Furthermore,the control effort is very low,which means the glider with limited power storage has longer range and higher endurance.
文摘Automatic gauge control is an essentially nonlinear process varying with time delay,and stochastically varying input and process noise always influence the target gauge control accuracy.To improve the control capability of feedforward automatic gauge control,Kalman filter was employed to filter the noise signal transferred from one stand to another.The linearized matrix that the Kalman filter algorithm needed was concluded;thus,the feedforward automatic gauge control architecture was dynamically optimized.The theoretical analyses and simulation show that the proposed algorithm is reasonable and effective.
基金This work was supported by the key project under the National Science and Technology Supporting Program of China(No.2006BAC19B01-05)the project of Research Fund of State Key Joint Laboratory of Environmental Simulation and Pollution Control.
文摘To improve the efficiency of nitrogen removalwith lower energy consumption,the study of feedforwardcontrol was carried out on a pilot-scale anaerobic-anoxicoxic(AAO)plant for the treatment of municipal wastewater.The effluent qualities of the pilot plant underdifferent control strategies were investigated.The resultsindicated that the change of external recycle was not asuitable approach to regulate the sludge concentration ofplug-flow reactors;adjusting the aeration valve anddissolved oxygen set-point according to ammonia loadcould overcome the impact of influent fluctuation;and thedenitrification potential could be estimated based on thetransit time of anoxic zone and the relative content ofcarbon resource entering the anoxic zone.Simple feedforwardcontrol strategies for aeration and internal recyclewere subsequently proposed and validated.The nitrogenremoval was successfully improved in the pilot plant.Theeffluent total nitrogen had decreased by 29.9%and wassteadily controlled below 15 mg·L^(-1).Furthermore,approximately 38%of the energy for aeration had beensaved.
基金This project was supported by the National Natural Science Foundation of China (60074001) and the Natural ScienceFoundation of Shandong Province (Y2000G02)
文摘The optimal control problem for linear time-varying systems affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions is consider and a design procedure of a feedforward and feedbaek optimal controller is presented. The condition of existence and uniqueness of the control law is given. The disturbanee observer is proposed to make the feedforward control law realizable physically. Simulation results demonstrate that the feedforward and feedbaek optimal control law is more effective and robust than the elassical state feedbaek control law with respect to external disturbanees.
文摘This paper proposes a neural network-based intelligent feedforward gust alleviation framework,which includes a neural network identification model and a neural network controller.A neural network training dataset is formed by collecting flight data and the gust data encountered during the aircraft flight.A neural network identification model is first trained to accurately predict the aircraft’s output.Then,based on the output of the identification model and the collected flight data,the parameters of the time-delay neural network controller are obtained through a learning process.The simulation results show that the designed intelligent controller has good gust alleviation effects for both continuous turbulence excitation and discrete gust excitation.For example,when the aircraft is 40000 kg and the flight speed is 0.81Ma,the controller achieves a 67.82%reduction in wingtip acceleration and a 35.90%reduction in center of mass acceleration under continuous turbulence excitation.When considering the measurement uncertainties,such as noise existing in the collected data,the trained controller can still achieve an acceptable gust alleviation effect.Finally,considering a flight in which the aircraft mass is constantly changing,the intelligent controller,which continuously learns from new flight data,maintains a good gust alleviation effect throughout the flight.
基金Supported partly by the Promoting Science and Technology by the Japan Ministry of Education,Culture,Sports,Science and Technology and the SCOPE of the Ministry of Internal Affairs and Communications (MIC),Japan (No.071705001)
文摘A three-dimensional （3-D） physiological articulatory model was developed to account for the biomechanical properties of the speech organs in speech production. Control of the model to investigate the mechanism of speech production requires an efficient control module to estimate muscle activation patterns, which is used to manipulate the 3-D physiological articulatory model, according to the desired articulatory posture. For this purpose, a feedforward control strategy was developed by mapping the articulatory target to the corresponding muscle activation pattern via the intrinsic representation of vowel articulation. In this process, the articulatory postures are first mapped to the corresponding intrinsic representations; then, the articulatory postures are clustered in the intrinsic representations space and a nonlinear function is approximated for each cluster to map the intrinsic representation of vowel articulation to the muscle activation pattern by using general regression neural networks （GRNN）. The results show that the feedforward control module is able to manipulate the 3-D physiological articulatory model for vowel production with high accuracy both acoustically and articulatorily.
