A compound controller is proposed to alleviate the considerable chattering in output of zero phase error tracking controller (ZPETC), when the flight simulator losses command data of simulation signal. Besides, the ...A compound controller is proposed to alleviate the considerable chattering in output of zero phase error tracking controller (ZPETC), when the flight simulator losses command data of simulation signal. Besides, the shortcomings, caused by conventional differential methods in retrieving velocity and acceleration signals, are avoided to a certain extent. The compound controller based on disturbance observer (DOB) is composed of a feed-forward controller and a feedback controller. It estimates velocity and acceleration of unknown tracking signal, and also velocity response with an approximate method for differential. The experiments on a single-axis flight simulator show that the proposed method has strong robustness against parameter perturbations and external disturbances, owing to the introduced DOB. Compared with the scheme with ZPETC, the proposed scheme possesses more simple design and better tracking performance. Moreover, it is less sensitive to position command distortion of flight simulator.展开更多
A robust controller for bank to turn(BTT) missiles with aerodynamic fins and reaction jet control system(RCS) is developed based on nonlinear control dynamic models comprising couplings and aerodynamic uncertainties. ...A robust controller for bank to turn(BTT) missiles with aerodynamic fins and reaction jet control system(RCS) is developed based on nonlinear control dynamic models comprising couplings and aerodynamic uncertainties. The fixed time convergence theory is incorporated with the sliding mode control technique to ensure that the system tracks the desired command within uniform bounded time under different initial conditions. Unlike previous terminal sliding mode approaches, the bound of settling time is independent of the initial state, which means performance metrics like convergence rate can be predicted beforehand. To reduce the burden of control design in terms of robustness, extended state observer(ESO) is introduced for uncertainty estimation with the output substituted into the controller as feedforward compensation. Cascade control structure is employed with the proposed control law and therein the compound control signal is obtained.Afterwards, control inputs for two kinds of actuators are allocated on the basis of their inherent characteristics. Finally, a number of simulations are carried out and demonstrate the effectiveness of the designed controller.展开更多
The impact dynamics, impact effect, and post-impact unstable motion sup- pression of free-floating space manipulator capturing a satellite on orbit are analyzed. Firstly, the dynamics equation of free-floating space m...The impact dynamics, impact effect, and post-impact unstable motion sup- pression of free-floating space manipulator capturing a satellite on orbit are analyzed. Firstly, the dynamics equation of free-floating space manipulator is derived using the sec- ond Lagrangian equation. Combining the momentum conservation principle, the impact dynamics and effect between the space manipulator end-effector and satellite of the cap- ture process are analyzed with the momentum impulse method. Focusing on the unstable motion of space manipulator due to the above impact effect, a robust adaptive compound control algorithm is designed to suppress the above unstable motion. There is no need to control the free-floating base position to save the jet fuel. Finally, the simulation is proposed to show the impact effect and verify the validity of the control algorithm.展开更多
This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil le...This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations: the first-order kinetics equation [N1=N0 (1-e^-kt)], Elovich equation (N1=a + blnt), and parabola equation (N1=a + bt^0.5), with the best fitting by the first-order kinetics equation for different N (r= 0.9569^**-0.9999^**). The release potentials (No values estimated by the first-order kinetics equation) of different N in the UCRF decreased in the order of total N 〉 DON 〉 urea-N 〉 NH4^+-N 〉 NO3^-N in water, and total N 〉 NH4^+-N 〉 DON 〉 urea-N 〉 NO3^--N in soil, respectively, being in accordance with cumulative amounts of N release. The constants of N release rate (k values and b values) for different N forms were in decreasing order of total N 〉 DON 〉 NH4^+-N 〉 NO3^--N in water, whereas the k values were urea- N 〉DON 〉 NH4^+-N 〉 total N 〉 NO3^--N, and the b values were total N 〉 NH4^+-N 〉 DON 〉 NO3^--N 〉 urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg^-1, and 5.17 kg kg^-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0 (l-e^kt)] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.展开更多
To solve the control allocation problem of dual aero/jet vane control missile, dynamics e- quations in longitudinal plane are derived, and the structure of compound control loop is designed based on attitude autopilot...To solve the control allocation problem of dual aero/jet vane control missile, dynamics e- quations in longitudinal plane are derived, and the structure of compound control loop is designed based on attitude autopilot. Four brief compound control allocation strategies are researched and an- alyzed. Furthermore, a new strategy called chain combination variable proportional coefficient strat- egy based on rudder effect is presented. By simulation of initial climb trajectory, the characteristics of all the strategies are researched, and the results illustrate that the new strategy can meet the re- quirement well.展开更多
Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering...Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering motor rapidly rotates, extra force is directly superimposed on the original static loading error, which becomes one of the main sources of the final error. It is key to achieve ELS precise loading control for the entire EPS test bench. Therefore, a three-part compound control algorithm is proposed to improve the loading accuracy. First, a fuzzy proportional–integral plus feedforward controller with force feedback is presented. Second, a friction compensation algorithm is established to reduce the influence of friction. Then, the relationships between each quantity and the extra force are analyzed when the steering motor rapidly rotates, and a net torque feedforward compensation algorithm is proposed to eliminate the extra force. The compound control algorithm was verified through simulations and experiments. The results show that the tracking performance of the compound control algorithm satisfies the demands of engineering practice, and the extra force in the ELS system can be suppressed by the net torque corresponding to the actuator’s acceleration.展开更多
Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which...Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which can obtain optimal dynamic damping ratio through real-time altering pressure-flow gain of the throttle control unit, improve the dynamic characteristic of tension follow-up control for the tension system with high inertia loads. Moreover, the characteristic when the cable linear velocity variation causes change of tension is investigated, and a compound control strategy is proposed. The theoretical analysis and experimental results show that the electro-hydraulic compound control circuit is effective and the characteristic of the compound control strategy is satisfactory.展开更多
Aiming at characteristic of time delay, time-varying parameters and much disturb in glass greenhouse heating system, fuzzy smith cascade compound control policy based on typical PID cascade compound control policy is ...Aiming at characteristic of time delay, time-varying parameters and much disturb in glass greenhouse heating system, fuzzy smith cascade compound control policy based on typical PID cascade compound control policy is proposed. Simulation results show that it is effective to overcome the influence of time delay on stability of control system and the system possesses strong robust and good dynamic performance..展开更多
A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control...A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.展开更多
The relevant results of thermodynamics simulation test, recrystallization study and FEM numercal simulation are described. A method is also introduced that the controlled hot forming is carried out by adopting the pro...The relevant results of thermodynamics simulation test, recrystallization study and FEM numercal simulation are described. A method is also introduced that the controlled hot forming is carried out by adopting the program of expansion-extrusion compound forming.展开更多
Gas turbine engines must be operated by means of control,and how to achieve multivariable control decoupling with aero-engine control constraints is an open thorny issue attracting increasingly more attention.The pape...Gas turbine engines must be operated by means of control,and how to achieve multivariable control decoupling with aero-engine control constraints is an open thorny issue attracting increasingly more attention.The paper considers the multivariable decoupling problems of aero-engines by using a compound controller,which originates from the fact that it is impossible to eliminate all the nonlinear dynamics of system to obtain desired constant linear closed-loop system by using full actuated control because of modeling errors and some physical constraints.Two controllers are involved in the compound controller.One is a fully actuated controller and the other is classical feedback controller.In order to use fully actuated control and maintain the accuracy of engine model,a full state scheduling linear parameter-varying(LPV)modeling method is proposed based on fuzzy neural network weights.For a general input matrix of the system,its generalized inverse is applied to design fully actuated controller to result in a pseudolinear system.Combined with a feedback controller and control limiter,the control synthesis is achieved.The simulation shows that the proposed method is possessed of a better decoupling and tracking effect compared with traditional control approach.展开更多
A quantised backstepping robust guidance law of three-dimension(3-D)space for compound control of reaction control jets and aerodynamic surfaces is proposed to attenuate the unknown target manoeuvre in this paper.The ...A quantised backstepping robust guidance law of three-dimension(3-D)space for compound control of reaction control jets and aerodynamic surfaces is proposed to attenuate the unknown target manoeuvre in this paper.The presented guidance law guarantees that the rates of line of sight converge to a residual circle centred at the origin whose radius is depended on the target manoeuvres,quantised length and guidance law gains.The simulations are given to illustrate the effectiveness of the proposed guidance law.展开更多
基金Program for New Century Excellent Talents in University (NCET-07-0044)
文摘A compound controller is proposed to alleviate the considerable chattering in output of zero phase error tracking controller (ZPETC), when the flight simulator losses command data of simulation signal. Besides, the shortcomings, caused by conventional differential methods in retrieving velocity and acceleration signals, are avoided to a certain extent. The compound controller based on disturbance observer (DOB) is composed of a feed-forward controller and a feedback controller. It estimates velocity and acceleration of unknown tracking signal, and also velocity response with an approximate method for differential. The experiments on a single-axis flight simulator show that the proposed method has strong robustness against parameter perturbations and external disturbances, owing to the introduced DOB. Compared with the scheme with ZPETC, the proposed scheme possesses more simple design and better tracking performance. Moreover, it is less sensitive to position command distortion of flight simulator.
基金supported by the National Natural Science Foundation of China(11572036)
文摘A robust controller for bank to turn(BTT) missiles with aerodynamic fins and reaction jet control system(RCS) is developed based on nonlinear control dynamic models comprising couplings and aerodynamic uncertainties. The fixed time convergence theory is incorporated with the sliding mode control technique to ensure that the system tracks the desired command within uniform bounded time under different initial conditions. Unlike previous terminal sliding mode approaches, the bound of settling time is independent of the initial state, which means performance metrics like convergence rate can be predicted beforehand. To reduce the burden of control design in terms of robustness, extended state observer(ESO) is introduced for uncertainty estimation with the output substituted into the controller as feedforward compensation. Cascade control structure is employed with the proposed control law and therein the compound control signal is obtained.Afterwards, control inputs for two kinds of actuators are allocated on the basis of their inherent characteristics. Finally, a number of simulations are carried out and demonstrate the effectiveness of the designed controller.
基金supported by the National Natural Science Foundation of China(Nos.11072061 and 11372073)the Natural Science Foundation of Fujian Province(No.2010J01003)
文摘The impact dynamics, impact effect, and post-impact unstable motion sup- pression of free-floating space manipulator capturing a satellite on orbit are analyzed. Firstly, the dynamics equation of free-floating space manipulator is derived using the sec- ond Lagrangian equation. Combining the momentum conservation principle, the impact dynamics and effect between the space manipulator end-effector and satellite of the cap- ture process are analyzed with the momentum impulse method. Focusing on the unstable motion of space manipulator due to the above impact effect, a robust adaptive compound control algorithm is designed to suppress the above unstable motion. There is no need to control the free-floating base position to save the jet fuel. Finally, the simulation is proposed to show the impact effect and verify the validity of the control algorithm.
文摘This study examined the release characteristics of different N forms in an uncoated slow/controlled-release compound fertilizer (UCRF) and the N uptake and N-use efficiency by rice plants. Water dissolution, soil leaching, and pot experiments were employed. The dynamics of N release from the UCRF could be quantitatively described by three equations: the first-order kinetics equation [N1=N0 (1-e^-kt)], Elovich equation (N1=a + blnt), and parabola equation (N1=a + bt^0.5), with the best fitting by the first-order kinetics equation for different N (r= 0.9569^**-0.9999^**). The release potentials (No values estimated by the first-order kinetics equation) of different N in the UCRF decreased in the order of total N 〉 DON 〉 urea-N 〉 NH4^+-N 〉 NO3^-N in water, and total N 〉 NH4^+-N 〉 DON 〉 urea-N 〉 NO3^--N in soil, respectively, being in accordance with cumulative amounts of N release. The constants of N release rate (k values and b values) for different N forms were in decreasing order of total N 〉 DON 〉 NH4^+-N 〉 NO3^--N in water, whereas the k values were urea- N 〉DON 〉 NH4^+-N 〉 total N 〉 NO3^--N, and the b values were total N 〉 NH4^+-N 〉 DON 〉 NO3^--N 〉 urea-N in soil. Compared with a common compound fertilizer, the N-use efficiency, N-agronomy efficiency, and N-physiological efficiency of the UCRF were increased by 11.4%, 8.32 kg kg^-1, and 5.17 kg kg^-1, respectively. The ratios of different N to total N in the UCRF showed significant correlation with N uptake by rice plants. The findings showed that the first-order kinetics equation [Nt=N0 (l-e^kt)] could be used to describe the release characteristics of different N forms in the fertilizer. The UCRF containing different N forms was more effective in facilitating N uptake by rice compared with the common compound fertilizer containing single urea-N form.
文摘To solve the control allocation problem of dual aero/jet vane control missile, dynamics e- quations in longitudinal plane are derived, and the structure of compound control loop is designed based on attitude autopilot. Four brief compound control allocation strategies are researched and an- alyzed. Furthermore, a new strategy called chain combination variable proportional coefficient strat- egy based on rudder effect is presented. By simulation of initial climb trajectory, the characteristics of all the strategies are researched, and the results illustrate that the new strategy can meet the re- quirement well.
基金Supported by National Natural Science Foundation of China (Grant No. 51505178)China Postdoctoral Science Foundation (Grant No. 2014M561289)。
文摘Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering motor rapidly rotates, extra force is directly superimposed on the original static loading error, which becomes one of the main sources of the final error. It is key to achieve ELS precise loading control for the entire EPS test bench. Therefore, a three-part compound control algorithm is proposed to improve the loading accuracy. First, a fuzzy proportional–integral plus feedforward controller with force feedback is presented. Second, a friction compensation algorithm is established to reduce the influence of friction. Then, the relationships between each quantity and the extra force are analyzed when the steering motor rapidly rotates, and a net torque feedforward compensation algorithm is proposed to eliminate the extra force. The compound control algorithm was verified through simulations and experiments. The results show that the tracking performance of the compound control algorithm satisfies the demands of engineering practice, and the extra force in the ELS system can be suppressed by the net torque corresponding to the actuator’s acceleration.
基金This project is supported by National Natural Science Foundation of China (No.50475105).
文摘Based on the pressure regulation circuit adopting electro-hydraulic proportional relief valve to control tension, a new type of electro-hydraulic compound control circuit with throttle control unit is presented, which can obtain optimal dynamic damping ratio through real-time altering pressure-flow gain of the throttle control unit, improve the dynamic characteristic of tension follow-up control for the tension system with high inertia loads. Moreover, the characteristic when the cable linear velocity variation causes change of tension is investigated, and a compound control strategy is proposed. The theoretical analysis and experimental results show that the electro-hydraulic compound control circuit is effective and the characteristic of the compound control strategy is satisfactory.
文摘Aiming at characteristic of time delay, time-varying parameters and much disturb in glass greenhouse heating system, fuzzy smith cascade compound control policy based on typical PID cascade compound control policy is proposed. Simulation results show that it is effective to overcome the influence of time delay on stability of control system and the system possesses strong robust and good dynamic performance..
基金This project is supported by National Natural Science Foundation of China (No.50275102)Provincial Foundation for Abroad Return People of Shanxi (No.101045).
文摘A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved.
文摘The relevant results of thermodynamics simulation test, recrystallization study and FEM numercal simulation are described. A method is also introduced that the controlled hot forming is carried out by adopting the program of expansion-extrusion compound forming.
基金supported by National Science and Technology Major Project(2017-V-0010-0060,2017-V-0013-0065,J2019-V-0010-0104),Original exploration project of National Natural Science Foundation of China(62250056)Major Basic Research of Natural Science Foundation of Shandong Province(ZR2021ZD14)+2 种基金High-Level Talent Team Project of Qingdao West Coast New Area(RCTD-JC-2019-05)Key Research and Development Program of Shandong Province(2020CXGC01208)National Natural Science Foundation of China(51506176).
文摘Gas turbine engines must be operated by means of control,and how to achieve multivariable control decoupling with aero-engine control constraints is an open thorny issue attracting increasingly more attention.The paper considers the multivariable decoupling problems of aero-engines by using a compound controller,which originates from the fact that it is impossible to eliminate all the nonlinear dynamics of system to obtain desired constant linear closed-loop system by using full actuated control because of modeling errors and some physical constraints.Two controllers are involved in the compound controller.One is a fully actuated controller and the other is classical feedback controller.In order to use fully actuated control and maintain the accuracy of engine model,a full state scheduling linear parameter-varying(LPV)modeling method is proposed based on fuzzy neural network weights.For a general input matrix of the system,its generalized inverse is applied to design fully actuated controller to result in a pseudolinear system.Combined with a feedback controller and control limiter,the control synthesis is achieved.The simulation shows that the proposed method is possessed of a better decoupling and tracking effect compared with traditional control approach.
基金National Science Foundation of China[grant number 61673050]Aeronautical Science Foundation of China[grant number 201401M5001]Open Research Project of the State Key Laboratory of Industrial Control Technology,Zhejiang University,China[grant number ICT1600229].
文摘A quantised backstepping robust guidance law of three-dimension(3-D)space for compound control of reaction control jets and aerodynamic surfaces is proposed to attenuate the unknown target manoeuvre in this paper.The presented guidance law guarantees that the rates of line of sight converge to a residual circle centred at the origin whose radius is depended on the target manoeuvres,quantised length and guidance law gains.The simulations are given to illustrate the effectiveness of the proposed guidance law.