In light of the high nonlinearity of LuGre friction model, a novel method based on ant colony algorithm(ACA) for identifying the friction parameters of flight simulation servo system is proposed. ACA is a parallelized...In light of the high nonlinearity of LuGre friction model, a novel method based on ant colony algorithm(ACA) for identifying the friction parameters of flight simulation servo system is proposed. ACA is a parallelized bionic optimization algorithm inspired from the behavior of real ants, and a kind of positive feedback mechanism is adopted in ACA. On the basis of brief introduction of LuGre friction model, a method for identifying the static LuGre friction parameters and the dynamic LuGre friction parameters using ACA is derived. Finally, this new friction parameter identification scheme is applied to a electric-driven flight simulation servo system with high precision. Simulation and application results verify the feasibility and the effectiveness of the scheme. It provides a new way to identify the friction parameters of LuGre model.展开更多
Adaptive control of servo actuator with nonlinear friction compensation is addressed. LuGre dynamic friction model is adopted to characterize the nonlinear friction and a new kind of slid ing mode observer is designe...Adaptive control of servo actuator with nonlinear friction compensation is addressed. LuGre dynamic friction model is adopted to characterize the nonlinear friction and a new kind of slid ing mode observer is designed to estimate the internal immeasurable state of LuGre model. Based on the estimated friction state, adaptive laws are designed to identify the unknown model parameters and the external disturbances, and the system stability and asymptotic trajectory tracking perform ance are guaranteed by Lyapunov function. The position tracking performance is verified by the ex perimental results.展开更多
A new modified LuGre friction model is presented for electromagnetic valve actuator system.The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear cont...A new modified LuGre friction model is presented for electromagnetic valve actuator system.The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear continuous switch function.The proposed new friction model solves the implementation problems with the traditional LuGre model at high speeds.An improved artificial fish swarm algorithm(IAFSA)method which combines the chaotic search and Gauss mutation operator into traditional artificial fish swarm algorithm is used to identify the parameters in the proposed modified LuGre friction model.The steady state response experiments and dynamic friction experiments are implemented to validate the effectiveness of IAFSA algorithm.The comparisons between the measured dynamic friction forces and the ones simulated with the established mathematic friction model at different frequencies and magnitudes demonstrate that the proposed modified LuGre friction model can give accurate simulation about the dynamic friction characteristics existing in the electromagnetic valve actuator system.The presented modelling and parameter identification methods are applicable for many other high-speed mechanical systems with friction.展开更多
A nonlinear dynamic friction control is dealt with using dynamic friction observer and intelligent cantrol. The adaptive dynamic friction obsrver based on the LuGre friction is proposed to estimate the friction parame...A nonlinear dynamic friction control is dealt with using dynamic friction observer and intelligent cantrol. The adaptive dynamic friction obsrver based on the LuGre friction is proposed to estimate the friction parameters and a directly friction state variable The dynamic structured Fuzzy Neural Network （RFNN） is designed to give additional robustness to the cantrol system under the presence of the friction model uncertainty. A proposed composite cantrol scheme is applied to the position tracking control of the servo systen. The performances of the proposed friction observer and the friction controller are demonstrated by simulation.展开更多
Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness t...Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.展开更多
In order to control the vehicle body position precisely,1/4 nonlinear mathematical model of hydro-pneumatic suspension is established,and the influence of the frictional force in a hydraulic cylinder is analyzed.The f...In order to control the vehicle body position precisely,1/4 nonlinear mathematical model of hydro-pneumatic suspension is established,and the influence of the frictional force in a hydraulic cylinder is analyzed.The friction characteristics are described based on the LuGre model when the piston of a hydraulic actuator is operated at a low speed.Due to the fact parameters of the friction model are effected by the system condition,an adaptive friction compensation（AFC）controller is designed through the Backstepping method,and a dual-observer has been implemented to estimate the friction state.The global asymptotic convergence of a closed-loop system is proven by the Lyapunov theorem.The simulation results show that the positional accuracy of the adaptive friction compensation yiedls a significant improvement in the vehicle height adjustment as compared to the PID control,demonstrating the effectiveness of the adaptive fiction compensation method in the vehicle height adjustable system of the hydro-pneumatic suspension.展开更多
The accurate estimation of tire-pavement friction,especially under wet conditions,is critical to ensure pavement safety.For this purpose,this paper develops a modified tirepavement friction model which takes the effec...The accurate estimation of tire-pavement friction,especially under wet conditions,is critical to ensure pavement safety.For this purpose,this paper develops a modified tirepavement friction model which takes the effect of pavement texture and water film into consideration.The influence of pavement texture is quantified by a newly proposed parameter called texture influence coefficient,which is related to the real contact patch of tirepavement.The water effect is calculated from two parts,namely lubrication effect and hydrodynamic effect.Based on these two steps,a modified average lumped LuGre(ALL)model is developed.The proposed model is calibrated and verified by GripTester data collected under different vehicle velocities and water film thicknesses.The root mean square error between the calculated value of the model and the measured value is 0.023.In addition,the effects of vehicle velocity,slip rate,water film thickness,and pavement type on the friction coefficient are analyzed by numerical calculation.The results show that the friction coefficient reaches the maximum when the slip rate is in the range of[0.15,0.20].The increases in the vehicle speed and water film thickness will lead to the decrease in the friction coefficient.Besides,in thin water film(<1 millimeter)conditions,the deterioration effect of water film thickness on the friction coefficient is more remarkable.The results prove that the modified tire-pavement friction model provides a precise and reliable way to estimate the friction coefficient of pavement,which can assist the pavement management systems in risk warning and safety guarantee.展开更多
The friction force is an important environmental factor that influences dynamic walking.While most of the related works simply assume static friction or Coulomb friction,we use the LuGre friction,which accounts for bo...The friction force is an important environmental factor that influences dynamic walking.While most of the related works simply assume static friction or Coulomb friction,we use the LuGre friction,which accounts for both static and dynamic effects,to model the horizontal ground reaction force of passive dynamic walking.We present a detailed mathematical modeling method and perform numerical simulations using it.Furthermore,we analyze the ground surface cases of the Coulomb friction condition and static friction condition to verify the model’s generalization.We discover the required condition for the existence of the period-1 gait through investigation.Our mathematical model and theoretical analysis add to our understanding of passive dynamic walking,which helps to positively utilize the natural dynamics of the legged locomotion system in control design.展开更多
文摘In light of the high nonlinearity of LuGre friction model, a novel method based on ant colony algorithm(ACA) for identifying the friction parameters of flight simulation servo system is proposed. ACA is a parallelized bionic optimization algorithm inspired from the behavior of real ants, and a kind of positive feedback mechanism is adopted in ACA. On the basis of brief introduction of LuGre friction model, a method for identifying the static LuGre friction parameters and the dynamic LuGre friction parameters using ACA is derived. Finally, this new friction parameter identification scheme is applied to a electric-driven flight simulation servo system with high precision. Simulation and application results verify the feasibility and the effectiveness of the scheme. It provides a new way to identify the friction parameters of LuGre model.
基金Supported by State Key Laboratory of Explosion Science and Technology(QNKT11-08)
文摘Adaptive control of servo actuator with nonlinear friction compensation is addressed. LuGre dynamic friction model is adopted to characterize the nonlinear friction and a new kind of slid ing mode observer is designed to estimate the internal immeasurable state of LuGre model. Based on the estimated friction state, adaptive laws are designed to identify the unknown model parameters and the external disturbances, and the system stability and asymptotic trajectory tracking perform ance are guaranteed by Lyapunov function. The position tracking performance is verified by the ex perimental results.
基金Project(2015BAG06B00)supported by the National Key Technology Research from Development Program of the Ministry of Science and Technology of China
文摘A new modified LuGre friction model is presented for electromagnetic valve actuator system.The modification to the traditional LuGre friction model is made by adding an acceleration-dependent part and a nonlinear continuous switch function.The proposed new friction model solves the implementation problems with the traditional LuGre model at high speeds.An improved artificial fish swarm algorithm(IAFSA)method which combines the chaotic search and Gauss mutation operator into traditional artificial fish swarm algorithm is used to identify the parameters in the proposed modified LuGre friction model.The steady state response experiments and dynamic friction experiments are implemented to validate the effectiveness of IAFSA algorithm.The comparisons between the measured dynamic friction forces and the ones simulated with the established mathematic friction model at different frequencies and magnitudes demonstrate that the proposed modified LuGre friction model can give accurate simulation about the dynamic friction characteristics existing in the electromagnetic valve actuator system.The presented modelling and parameter identification methods are applicable for many other high-speed mechanical systems with friction.
基金supported by Ministry of Knowledge and Economy,Koreathe ITRC(Information Technology Research Center)support program(ⅡTA-2009-C1090-0902-0004)
文摘A nonlinear dynamic friction control is dealt with using dynamic friction observer and intelligent cantrol. The adaptive dynamic friction obsrver based on the LuGre friction is proposed to estimate the friction parameters and a directly friction state variable The dynamic structured Fuzzy Neural Network （RFNN） is designed to give additional robustness to the cantrol system under the presence of the friction model uncertainty. A proposed composite cantrol scheme is applied to the position tracking control of the servo systen. The performances of the proposed friction observer and the friction controller are demonstrated by simulation.
基金National Science Fund for Distinguished Young Scholars (50825502)
文摘Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.
基金Supported by the National Natural Science Foundation of China(51005018)
文摘In order to control the vehicle body position precisely,1/4 nonlinear mathematical model of hydro-pneumatic suspension is established,and the influence of the frictional force in a hydraulic cylinder is analyzed.The friction characteristics are described based on the LuGre model when the piston of a hydraulic actuator is operated at a low speed.Due to the fact parameters of the friction model are effected by the system condition,an adaptive friction compensation（AFC）controller is designed through the Backstepping method,and a dual-observer has been implemented to estimate the friction state.The global asymptotic convergence of a closed-loop system is proven by the Lyapunov theorem.The simulation results show that the positional accuracy of the adaptive friction compensation yiedls a significant improvement in the vehicle height adjustment as compared to the PID control,demonstrating the effectiveness of the adaptive fiction compensation method in the vehicle height adjustable system of the hydro-pneumatic suspension.
基金supported by the Ministry of Transport of China(No.2020-ZD3-025)the Shanghai Science and Technology Commission of China(No.22XD1433300).
文摘The accurate estimation of tire-pavement friction,especially under wet conditions,is critical to ensure pavement safety.For this purpose,this paper develops a modified tirepavement friction model which takes the effect of pavement texture and water film into consideration.The influence of pavement texture is quantified by a newly proposed parameter called texture influence coefficient,which is related to the real contact patch of tirepavement.The water effect is calculated from two parts,namely lubrication effect and hydrodynamic effect.Based on these two steps,a modified average lumped LuGre(ALL)model is developed.The proposed model is calibrated and verified by GripTester data collected under different vehicle velocities and water film thicknesses.The root mean square error between the calculated value of the model and the measured value is 0.023.In addition,the effects of vehicle velocity,slip rate,water film thickness,and pavement type on the friction coefficient are analyzed by numerical calculation.The results show that the friction coefficient reaches the maximum when the slip rate is in the range of[0.15,0.20].The increases in the vehicle speed and water film thickness will lead to the decrease in the friction coefficient.Besides,in thin water film(<1 millimeter)conditions,the deterioration effect of water film thickness on the friction coefficient is more remarkable.The results prove that the modified tire-pavement friction model provides a precise and reliable way to estimate the friction coefficient of pavement,which can assist the pavement management systems in risk warning and safety guarantee.
基金supported by Fundamental Research Funds for the Central Universities,China(buctrc202215).
文摘The friction force is an important environmental factor that influences dynamic walking.While most of the related works simply assume static friction or Coulomb friction,we use the LuGre friction,which accounts for both static and dynamic effects,to model the horizontal ground reaction force of passive dynamic walking.We present a detailed mathematical modeling method and perform numerical simulations using it.Furthermore,we analyze the ground surface cases of the Coulomb friction condition and static friction condition to verify the model’s generalization.We discover the required condition for the existence of the period-1 gait through investigation.Our mathematical model and theoretical analysis add to our understanding of passive dynamic walking,which helps to positively utilize the natural dynamics of the legged locomotion system in control design.
