Dataset Information

Development of Magnetically Levitated Rotary Table for Repetitive Trajectory Tracking.

ABSTRACT: The magnetic levitation system has been considered as a promising actuator in micromachining areas of study. In order to improve the tracking performance and disturbance rejection of the magnetically levitated rotary table, an iterative learning PID control strategy with disturbance compensation is proposed. The estimated disturbance compensates for the control signals to enhance the active disturbance rejection ability. The iterative learning control is used as a feed-forward unit to further reduce the trajectory tracking error. The convergence and stability of the iterative learning PID with disturbance compensation are analysed. A series of comparative experiments are carried out on the in-house, custom-made, magnetically levitated rotary table, and the experimental results highlight the superiority of the proposed control strategy. The iterative learning PID with disturbance compensation enables the magnetically levitated rotary table to realize good tracking performance with complex external disturbance. The proposed control strategy strengthens the applicability of magnetically levitated systems in the mechanism manufacturing area.

SUBMITTER: Xu F

PROVIDER: S-EPMC9185631 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Development of Magnetically Levitated Rotary Table for Repetitive Trajectory Tracking.

Xu Fengqiu F Zhang Kaiyang K Xu Xianze X

Sensors (Basel, Switzerland) 20220603 11

The magnetic levitation system has been considered as a promising actuator in micromachining areas of study. In order to improve the tracking performance and disturbance rejection of the magnetically levitated rotary table, an iterative learning PID control strategy with disturbance compensation is proposed. The estimated disturbance compensates for the control signals to enhance the active disturbance rejection ability. The iterative learning control is used as a feed-forward unit to further re ...[more]

PMID: 35684891

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Project description:Due to the influence of coal rock shape, hardness, working environment and other factors in the cutting process of cantilever roadheader, the cutting head will produce irregular and violent vibration. As the rotary table of key stress components, its operation process stability, dynamic reliability and life affect the cutting efficiency and cutting stability of cantilever roadheader. In order to study the vibration characteristics of the rotary table in the cutting process, firstly, based on the theory of spatial force analysis and calculation, the spatial mechanical model of the rotary table of the cantilever roadheader is established. By solving the balance equation of the rotary table force system, the variation law of the load at the hinge ear of the rotary table with the cutting pitch angle and the horizontal angle is obtained. Secondly, based on the path transfer analysis method of working condition, the vibration data of cutting head, cutting cantilever, cutting lifting and rotary hydraulic cylinder under stable cutting condition are taken as input signals. By constructing the transfer path analysis model of rotary table working condition, the synthetic vibration of rotary table in cutting process is simulated, and the main vibration source of rotary table is determined. Then, the vibration contribution and contribution degree of each vibration excitation point to the hinge ear of rotary table are studied. By building a cutting test bench, the vibration response of rotary table in cutting process is tested to verify the correctness of the theoretical model.Thirdly, based on the frequency domain analysis method of random vibration fatigue life, combined with the S-N curve of the rotary table, the PSD curve at the maximum stress of the rotary table is obtained by modal excitation method, and the load data is imported into ANSYS nCode software to obtain the life cloud diagram and damage cloud diagram of the rotary table, and then the fatigue life of the rotary table under symmetrical cyclic load is solved. Finally, based on the response surface optimization analysis method, the maximum stress and maximum deformation of the rotary table are taken as the optimization objectives, and the aperture of each hinge ear of the rotary table is taken as the optimization variable. Based on Design Expert, a second-order regression model is established to realize the multi-objective optimization design of the key stress parts of the rotary table in the cutting process. The simulation results show that under the same cutting conditions, the maximum stress of the optimized rotary table is reduced by 15.82% year-on-year, and the maximum deformation is reduced by 24.70% year-on-year. The optimized rotary table structure can better adapt to the cutting process, which is beneficial to improve the service life of the rotary table and enhance its operation stability. The research results are beneficial to enrich the relevant research theory in the field of rotary table vibration of cantilever roadheader, and are beneficial to improve the service life of the rotary table and the efficiency of tunneling and mining.

Project description:ImportanceAlthough durable left ventricular assist device (LVAD) therapy has emerged as an important treatment option for patients with advanced heart failure refractory to pharmacological support, outcomes, including survival, beyond 2 years remain poorly characterized.ObjectiveTo report the composite end point of survival to transplant, recovery, or LVAD support free of debilitating stroke (Modified Rankin Scale score >3) or reoperation to replace the pump 5 years after the implant in participants who received the fully magnetically levitated centrifugal-flow HeartMate 3 or axial-flow HeartMate II LVAD in the MOMENTUM 3 randomized trial and were still receiving LVAD therapy at the 2-year follow-up.Design, setting, and participantsThis observational study was a 5-year follow-up of the MOMENTUM 3 trial, conducted in 69 US centers, that demonstrated superiority of the centrifugal-flow LVAD to the axial-flow pump with respect to survival to transplant, recovery, or LVAD support free of debilitating stroke or reoperation to replace the pump at 2 years. A total of 295 patients were enrolled between June 2019 to April 2021 in the extended-phase study, with 5-year follow-up completed in September 2021.ExposuresOf 1020 patients in the investigational device exemption per-protocol population, 536 were still receiving LVAD support at 2 years, of whom 289 received the centrifugal-flow pump and 247 received the axial-flow pump.Main outcomes and measuresThere were 10 end points evaluated at 5 years in the per-protocol population, including a composite of survival to transplant, recovery, or LVAD support free of debilitating stroke or reoperation to replace the pump between the centrifugal-flow and axial-flow pump groups and overall survival between the 2 groups.ResultsA total of 477 patients (295 enrolled and 182 provided limited data) of 536 patients still receiving LVAD support at 2 years contributed to the extended-phase analysis (median age, 62 y; 86 [18%] women). The 5-year Kaplan-Meier estimate of survival to transplant, recovery, or LVAD support free of debilitating stroke or reoperation to replace the pump in the centrifugal-flow vs axial-flow group was 54.0% vs 29.7% (hazard ratio, 0.55 [95% CI, 0.45-0.67]; P < .001). Overall Kaplan-Meier survival was 58.4% in the centrifugal-flow group vs 43.7% in the axial-flow group (hazard ratio, 0.72 [95% CI, 0.58-0.89]; P = .003). Serious adverse events of stroke, bleeding, and pump thrombosis were less frequent in the centrifugal-flow pump group.Conclusions and relevanceIn this observational follow-up study of patients from the MOMENTUM 3 randomized trial, per-protocol analyses found that receipt of a fully magnetically levitated centrifugal-flow LVAD vs axial-flow LVAD was associated with a better composite outcome and higher likelihood of overall survival at 5 years. These findings support the use of the fully magnetically levitated LVAD.Trial registrationClinicalTrials.gov Identifier: NCT02224755 and NCT03982979.

Dataset Information

Development of Magnetically Levitated Rotary Table for Repetitive Trajectory Tracking.

Publications

Development of Magnetically Levitated Rotary Table for Repetitive Trajectory Tracking.

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