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Hybrid iterative learning control of a flexible manipulator
This paper presents an investigation into the development of a hybrid control scheme with iterative learning for input tracking and end-point vibration suppression of a flexible manipulator system. The dynamic model of the system is derived using the finite element method. Initially, a collocated proportional-derivative (PD) controller using hub angle and hub velocity feedback is developed for control of rigid-body motion of the system. This is then extended to incorporate a non-collocated proportional-integral-derivative (PID) controller with iterative learning for control of vibration of the system. Simulation results of the response of the manipulator with the controllers are presented in the time and frequency domains. The performance of the hybrid iterative learning control scheme is assessed in terms of input tracking and level of vibration reduction in comparison to a conventionally designed PD-PID control scheme. The effectiveness of the control scheme in handling various payloads is also studied
On the efficiency of quantum lithography
Quantum lithography promises, in principle, unlimited feature resolution,
independent of wavelength. However, in the literature at least two different
theoretical descriptions of quantum lithography exist. They differ in to which
extent they predict that the photons retain spatial correlation from generation
to the absorption, and while both predict the same feature size, they differ
vastly in predicting how efficiently a quantum lithographic pattern can be
exposed.
Until recently, essentially all experiments reported have been performed in
such a way that it is difficult to distinguish between the two theoretical
explanations. However, last year an experiment was performed which gives
different outcomes for the two theories. We comment on the experiment and show
that the model that fits the data unfortunately indicates that the trade-off
between resolution and efficiency in quantum lithography is very unfavourable.Comment: 19 pages, extended version including a thorough mathematical
derivatio
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