Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely co...Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.展开更多
This paper presents a new type of automotive braking actuator for a kind of brake-by-wire system called decentralized electro-hydraulic braking system( DEHB) to replace the traditional automobile braking system. The a...This paper presents a new type of automotive braking actuator for a kind of brake-by-wire system called decentralized electro-hydraulic braking system( DEHB) to replace the traditional automobile braking system. The actuator of this system is driven by an electrical motor instead of the conventional vacuum booster to make the brake pressure be linearity controlled quickly. Therefore,the system has the advantages of quick response speed,good control performance and simple structure. Firstly,an overview of the actuator and the whole DEHB system is shown. Secondly,the possibility of this new kind of actuator working for the system is ensured based on some braking theories. Thirdly,the appropriate dynamic simulations are done to get some results to show the relations of different parameters and the effect of braking. Eventually,the proper parameters are determined to build a test bench which shows that DEHB system can achieve the maximum pressure of 13 MPa within 100 ms after parametric optimization,and meanwhile,the actuator is able to reduce pressure quickly after maintaining high pressure. All of the bench test results can meet with the design requirements and real demand of vehicle and this actuator may improve vehicle braking effect in the future. Besides,this actuator can be widely applied to the regenerative braking system because of its linear braking performance.展开更多
Most current researches working on improving stiffness focus on the application of control theories.But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated,so...Most current researches working on improving stiffness focus on the application of control theories.But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated,so the control action is lagged.Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms.In this paper,the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed.On this basis,the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward.And a scheme using double servo valves to realize flow feedforward compensation is presented,in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time.The two valves are arranged in parallel to control the cylinder jointly.Furthermore,the model of flow compensation is derived,by which the product of the amplitude and width of the valve’s pulse command signal can be calculated.And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations.Using the proposed scheme,simulations and experiments at different positions with different force changes are conducted.The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time.That is,system dynamic load stiffness is evidently raised.This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.展开更多
The position control system of an electro-hydraulic actuator system （EHAS） is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system： the friction and the in...The position control system of an electro-hydraulic actuator system （EHAS） is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system： the friction and the internal leakage. A variable load that simulates a realistic load in robotic excavator is taken as the trajectory reference. A method of control strategy that is implemented by employing a fuzzy logic controller （FLC） whose parameters are optimized using particle swarm optimization （PSO） is proposed. The scaling factors of the fuzzy inference system are tuned to obtain the optimal values which yield the best system performance. The simulation results show that the FLC is able to track the trajectory reference accurately for a range of values of orifice opening. Beyond that range, the orifice opening may introduce chattering, which the FLC alone is not sufficient to overcome. The PSO optimized FLC can reduce the chattering significantly. This result justifies the implementation of the proposed method in position control of EHAS.展开更多
In this paper,we deal with both velocity control and force control of a single-rod electro-hydraulic actuator subject to external disturbances and parameter uncertainties.In some implementations,both velocity control ...In this paper,we deal with both velocity control and force control of a single-rod electro-hydraulic actuator subject to external disturbances and parameter uncertainties.In some implementations,both velocity control and force control are required.Impedance control and an extended disturbance observer are combined to solve this issue.Impedance control is applied to regulate the dynamic relationship between the velocity and output force of the actuator,which can help avoid impact and keep a proper contact force on the environment or workpieces.Parameters of impedance rules are regulated by a fuzzy algorithm.An extended disturbance observer is employed to account for external disturbances and parameter uncertainties to achieve an accurate velocity tracking.A detailed model of load force dynamics is presented for the development of the extended disturbance observer.The stability of the whole system is analyzed.Experimental results demonstrate that the proposed control strategy has not only a high velocity tracking performance,but also a good force adjustment performance,and that it should be widely applied in construction and assembly.展开更多
基金supported by Research Foundation funded by Thu Dau Mot University。
文摘Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.
基金Sponsored by the National High Technology R&D Program of China(Grant No.2012AA111204 and 2012AA110903)National Key Basic Research Program of China(Grant No.2011CB711205)Free Research Project of State Key Laboratory of Automotive Safety and Energy(Grant No.zz2011-052)
文摘This paper presents a new type of automotive braking actuator for a kind of brake-by-wire system called decentralized electro-hydraulic braking system( DEHB) to replace the traditional automobile braking system. The actuator of this system is driven by an electrical motor instead of the conventional vacuum booster to make the brake pressure be linearity controlled quickly. Therefore,the system has the advantages of quick response speed,good control performance and simple structure. Firstly,an overview of the actuator and the whole DEHB system is shown. Secondly,the possibility of this new kind of actuator working for the system is ensured based on some braking theories. Thirdly,the appropriate dynamic simulations are done to get some results to show the relations of different parameters and the effect of braking. Eventually,the proper parameters are determined to build a test bench which shows that DEHB system can achieve the maximum pressure of 13 MPa within 100 ms after parametric optimization,and meanwhile,the actuator is able to reduce pressure quickly after maintaining high pressure. All of the bench test results can meet with the design requirements and real demand of vehicle and this actuator may improve vehicle braking effect in the future. Besides,this actuator can be widely applied to the regenerative braking system because of its linear braking performance.
基金supported by National Natural Science Foundation of China(Grant No.51075291)Shanxi Scholarship Council of China(Grant No.2012-076)
文摘Most current researches working on improving stiffness focus on the application of control theories.But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated,so the control action is lagged.Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms.In this paper,the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed.On this basis,the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward.And a scheme using double servo valves to realize flow feedforward compensation is presented,in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time.The two valves are arranged in parallel to control the cylinder jointly.Furthermore,the model of flow compensation is derived,by which the product of the amplitude and width of the valve’s pulse command signal can be calculated.And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations.Using the proposed scheme,simulations and experiments at different positions with different force changes are conducted.The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time.That is,system dynamic load stiffness is evidently raised.This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.
文摘The position control system of an electro-hydraulic actuator system （EHAS） is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system： the friction and the internal leakage. A variable load that simulates a realistic load in robotic excavator is taken as the trajectory reference. A method of control strategy that is implemented by employing a fuzzy logic controller （FLC） whose parameters are optimized using particle swarm optimization （PSO） is proposed. The scaling factors of the fuzzy inference system are tuned to obtain the optimal values which yield the best system performance. The simulation results show that the FLC is able to track the trajectory reference accurately for a range of values of orifice opening. Beyond that range, the orifice opening may introduce chattering, which the FLC alone is not sufficient to overcome. The PSO optimized FLC can reduce the chattering significantly. This result justifies the implementation of the proposed method in position control of EHAS.
基金the National Natural Science Foundation of China(No.51605256)the National High-Tech R&D Program(863)of China(No.2012AA041803)and the China Postdoctoral Science Foundation(No.2016M590633)。
文摘In this paper,we deal with both velocity control and force control of a single-rod electro-hydraulic actuator subject to external disturbances and parameter uncertainties.In some implementations,both velocity control and force control are required.Impedance control and an extended disturbance observer are combined to solve this issue.Impedance control is applied to regulate the dynamic relationship between the velocity and output force of the actuator,which can help avoid impact and keep a proper contact force on the environment or workpieces.Parameters of impedance rules are regulated by a fuzzy algorithm.An extended disturbance observer is employed to account for external disturbances and parameter uncertainties to achieve an accurate velocity tracking.A detailed model of load force dynamics is presented for the development of the extended disturbance observer.The stability of the whole system is analyzed.Experimental results demonstrate that the proposed control strategy has not only a high velocity tracking performance,but also a good force adjustment performance,and that it should be widely applied in construction and assembly.
