High-accuracy motion trajectory tracking control of a pneumatic cylinder driven by a proportional directional control valve was considered. A mathematical model of the system was developed firstly. Due to the time-var...High-accuracy motion trajectory tracking control of a pneumatic cylinder driven by a proportional directional control valve was considered. A mathematical model of the system was developed firstly. Due to the time-varying friction force in the cylinder, unmodeled dynamics, and unknown disturbances, there exist large extent of parametric uncertainties and rather severe uncertain nonlinearities in the pneumatic system. To deal with these uncertainties effectively, an adaptive robust controller was constructed in this work. The proposed controller employs on-line recursive least squares estimation(RLSE) to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodeled dynamics and disturbances. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology was applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping was used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Extensive experimental results were presented to illustrate the excellent achievable performance of the proposed controller and performance robustness to the load variation and sudden disturbance.展开更多
Based on theory of variable-mass system thermodynamics, the dynamic mathematic models of each component of the horizontal steam-launch system were established, and by the numerical simulation of the system launching p...Based on theory of variable-mass system thermodynamics, the dynamic mathematic models of each component of the horizontal steam-launch system were established, and by the numerical simulation of the system launching process, the thermodynamics and kinetics characteristics of the system with three valves of different flow characteristics were got. The simulation results show that the values of the peak-to-average ratios of dimensionless acceleration with the equal percentage valve, the linear valve and the quick opening valve are 1.355, 1.614 and 1.722, respectively, and the final values of the dimensionless velocities are 0.843, 0.957 and 1.0, respectively. In conclusion, the value of the dimensionless velocity with the equal percentage valve doesn't reach the set value of 0.90 when the dimensionless displacement is 0.82, while the system with the linear valve can meet the launching requirement, as well as the fluctuation range of dimensionless acceleration is less than that of the quick opening valve. Therefore, the system with the linear valve has the best performance among the three kinds of valves.展开更多
基金Projects(50775200,50905156)supported by the National Natural Science Foundation of China
文摘High-accuracy motion trajectory tracking control of a pneumatic cylinder driven by a proportional directional control valve was considered. A mathematical model of the system was developed firstly. Due to the time-varying friction force in the cylinder, unmodeled dynamics, and unknown disturbances, there exist large extent of parametric uncertainties and rather severe uncertain nonlinearities in the pneumatic system. To deal with these uncertainties effectively, an adaptive robust controller was constructed in this work. The proposed controller employs on-line recursive least squares estimation(RLSE) to reduce the extent of parametric uncertainties, and utilizes the sliding mode control method to attenuate the effects of parameter estimation errors, unmodeled dynamics and disturbances. Therefore, a prescribed motion tracking transient performance and final tracking accuracy can be guaranteed. Since the system model uncertainties are unmatched, the recursive backstepping design technology was applied. In order to solve the conflicts between the sliding mode control design and the adaptive control design, the projection mapping was used to condition the RLSE algorithm so that the parameter estimates are kept within a known bounded convex set. Extensive experimental results were presented to illustrate the excellent achievable performance of the proposed controller and performance robustness to the load variation and sudden disturbance.
基金Project(20080431380)supported by the National Postdoctoral Science Foundation,China
文摘Based on theory of variable-mass system thermodynamics, the dynamic mathematic models of each component of the horizontal steam-launch system were established, and by the numerical simulation of the system launching process, the thermodynamics and kinetics characteristics of the system with three valves of different flow characteristics were got. The simulation results show that the values of the peak-to-average ratios of dimensionless acceleration with the equal percentage valve, the linear valve and the quick opening valve are 1.355, 1.614 and 1.722, respectively, and the final values of the dimensionless velocities are 0.843, 0.957 and 1.0, respectively. In conclusion, the value of the dimensionless velocity with the equal percentage valve doesn't reach the set value of 0.90 when the dimensionless displacement is 0.82, while the system with the linear valve can meet the launching requirement, as well as the fluctuation range of dimensionless acceleration is less than that of the quick opening valve. Therefore, the system with the linear valve has the best performance among the three kinds of valves.
