This paper addresses double-loop robust tracking controller design of the miniaturized linear motor drive precision stage with mass and damping ratio uncertainties. As an inner-loop, a disturbance observer （DOB） is ...This paper addresses double-loop robust tracking controller design of the miniaturized linear motor drive precision stage with mass and damping ratio uncertainties. As an inner-loop, a disturbance observer （DOB） is employed to suppress exogenous low frequency disturbances such as friction and cutting force. To further eliminate the residual disturbance and to guarantee the robust tracking to the reference input, μ-synthesis outer-loop controller is designed. For eliminating the steady state error, a technique is proposed to design the μ-synthesis outer-loop controller with an integrator. A guideline to select the bandwidth of the Q-filter in the DOB is provided. Simulations using a model of a prototype micro-milling machine indicate that the proposed outer-loop synthesis scheme is superior to the H∞ suboptimal control in disturbance rejection performance and steady state tracking performance. Furthermore, it is shown experimentally that the proposed double-loop robust tracking controller improves the tracking performance of the stage by 29.6% over PID control with a DOB inner-loop.展开更多
We herein report the effective performance enhancement of the pentacene-based organic thin film transistors with silicon di- oxide dielectric by inserting a thin metal phthalocyanines interlayer between Au source/drai...We herein report the effective performance enhancement of the pentacene-based organic thin film transistors with silicon di- oxide dielectric by inserting a thin metal phthalocyanines interlayer between Au source/drain electrodes and the pentacene active layer. The threshold voltage decreased remarkably from ca. -20 V to a few volts （below -7.6 V） while the mobility in- creased 1.5-3 times after the insertion of the interlayer of only ca. 2 nm, which could be attributed to the reduction of the car- tier injection barrier. The results suggest a simple and effective way to achieve low-threshold-voltage pentacene-based organic thin film transistors with high mobility on silicon dioxide dielectric.展开更多
基金supported by the Canada Foundation for Innovation (CFI) and the National Natural Science Foundation of China (Grant No.50875257)
文摘This paper addresses double-loop robust tracking controller design of the miniaturized linear motor drive precision stage with mass and damping ratio uncertainties. As an inner-loop, a disturbance observer （DOB） is employed to suppress exogenous low frequency disturbances such as friction and cutting force. To further eliminate the residual disturbance and to guarantee the robust tracking to the reference input, μ-synthesis outer-loop controller is designed. For eliminating the steady state error, a technique is proposed to design the μ-synthesis outer-loop controller with an integrator. A guideline to select the bandwidth of the Q-filter in the DOB is provided. Simulations using a model of a prototype micro-milling machine indicate that the proposed outer-loop synthesis scheme is superior to the H∞ suboptimal control in disturbance rejection performance and steady state tracking performance. Furthermore, it is shown experimentally that the proposed double-loop robust tracking controller improves the tracking performance of the stage by 29.6% over PID control with a DOB inner-loop.
基金financially supported by the National Basic Research Program of China (973 Program) (Grant No. 2007CB936302)the National Natural Science Foundation of China (Grant No. 20833002)
文摘We herein report the effective performance enhancement of the pentacene-based organic thin film transistors with silicon di- oxide dielectric by inserting a thin metal phthalocyanines interlayer between Au source/drain electrodes and the pentacene active layer. The threshold voltage decreased remarkably from ca. -20 V to a few volts （below -7.6 V） while the mobility in- creased 1.5-3 times after the insertion of the interlayer of only ca. 2 nm, which could be attributed to the reduction of the car- tier injection barrier. The results suggest a simple and effective way to achieve low-threshold-voltage pentacene-based organic thin film transistors with high mobility on silicon dioxide dielectric.
