The background of this contribution is the enhancement of the achievable accuracy of servo-screw-presses. Therefore, the paper is concerned with the improvement of the dynamic precision for direct driven servo axes wh...The background of this contribution is the enhancement of the achievable accuracy of servo-screw-presses. Therefore, the paper is concerned with the improvement of the dynamic precision for direct driven servo axes which is still restricted by structural vibrations. For this purpose, a ball screw test rig was analyzed for which the standard cascade control structure was extended by an additional velocity feedback. This structural extension has the potential to improve the controller performance significantly due to a better damping of low frequent vibrations. Furthermore, a parametric dynamic model for the control structure was derived to investigate the effects of the controller extension. For this analysis, the influences of the used tuning factors and filters is discussed in the frequency domain based on bode plots. The results of these cognitions are transferred to the time domain and illustrated by step responses. In addition, an evaluation by the criterion of the IAE （integral of absolute error） and the Prony analysis is carried out. Finally, the results are experimentally verified at the ball screw test rig. The paper closes with the conclusions.展开更多
Ported wall extensions are important hydraulic structures used to reduce crosscurrents in upper approaches to locks.The effect of such extensions located upstream of a solid guard wall on flow characteristics depends ...Ported wall extensions are important hydraulic structures used to reduce crosscurrents in upper approaches to locks.The effect of such extensions located upstream of a solid guard wall on flow characteristics depends on many factors,including geometric and hydraulic parameters.In this study,the hydraulic performance of ported wall extensions was experimentally investigated in terms of the permeability coefficient,expanding angle,extension length,and flow depth.The results demonstrate that the dimensionless maximum transverse velocity is closely related to the permeability coefficient,expanding angle,and flow depth.By contrast,the dimensionless eddy length mainly depends on the permeability coefficient,expanding angle,and extension length.Furthermore,the optimum permeability coefficient increases with the expanding angle or flow depth,and it is approximately constant for different extension lengths.These results have the potential to provide direct guidance for the design of effective ported wall extensions in upper approaches to locks.展开更多
文摘The background of this contribution is the enhancement of the achievable accuracy of servo-screw-presses. Therefore, the paper is concerned with the improvement of the dynamic precision for direct driven servo axes which is still restricted by structural vibrations. For this purpose, a ball screw test rig was analyzed for which the standard cascade control structure was extended by an additional velocity feedback. This structural extension has the potential to improve the controller performance significantly due to a better damping of low frequent vibrations. Furthermore, a parametric dynamic model for the control structure was derived to investigate the effects of the controller extension. For this analysis, the influences of the used tuning factors and filters is discussed in the frequency domain based on bode plots. The results of these cognitions are transferred to the time domain and illustrated by step responses. In addition, an evaluation by the criterion of the IAE （integral of absolute error） and the Prony analysis is carried out. Finally, the results are experimentally verified at the ball screw test rig. The paper closes with the conclusions.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFB1600403)the Natural Science Foundation of Chongqing,China(Grant No.cstc2020jcyj-bshX0043).
文摘Ported wall extensions are important hydraulic structures used to reduce crosscurrents in upper approaches to locks.The effect of such extensions located upstream of a solid guard wall on flow characteristics depends on many factors,including geometric and hydraulic parameters.In this study,the hydraulic performance of ported wall extensions was experimentally investigated in terms of the permeability coefficient,expanding angle,extension length,and flow depth.The results demonstrate that the dimensionless maximum transverse velocity is closely related to the permeability coefficient,expanding angle,and flow depth.By contrast,the dimensionless eddy length mainly depends on the permeability coefficient,expanding angle,and extension length.Furthermore,the optimum permeability coefficient increases with the expanding angle or flow depth,and it is approximately constant for different extension lengths.These results have the potential to provide direct guidance for the design of effective ported wall extensions in upper approaches to locks.
