Pi (physik Instrumente) L.p.

Physik Instrument (pi) Gmbh & Co. Kg

Scott Jordan

Bernhard Geyer

Berthold Besch

The invention relates to a method and a circuit arrangement for the precise, dynamic, digital control of especially piezoelectric actuators for micropositioning systems, comprising a regulator, whereby in order to minimise position order deviations the future system behaviour is estimated and current correction signals for the purpose of a feedforward correction are obtained. According to the invention, the signal of the command variable is passed via a switchable bypass to a digital/analog converter with highest resolution for the purpose of reducing the latency times in the feedforward loop of the sampling system, with said converter being operated at the sampling rate of the sampling system. The feedforward loop leads to a fast digital/analog converter which is controlled independent of the sampling system. The output signals of the converters, which represent control voltages are supplied in an added-up form to the device to be controlled, in particular, to a piezoelectric actuator which together with a position sensor forms the controlled system.

Method and circuit arrangement for the precise dynamic digital control of especially piezoelectric actuators for micropositioning systems

Samples are taken of radiation throughput intensities while a radiation supplying, first element advances along a dithering displacement path, where the displacement path is spaced slightly away from but extends adjacent to an initial position of the first element and while a reference radiation signal is coupled radiatively between the first element and a counterpart, radiation receiving, second element. Those samples that are seen to be the greatest (I) are identified. From this information, a determination is made of at least the approximate direction, if not the approximate length of an optimization vector which separates the initial position of the first element from a radiative coupling, new position having a greater coupling efficiency. The first element is automatically moved according to the optimization vector so as to be at or substantially close to the new radiative coupling position.

Aligning apparatus and method using on-the-fly determination of throughput-profile gradient for current positioning of radiated influence supplier and/or receiver

In one embodiment, one or more less significant input bits (LSB's) of a digital-to-analog converter (DAC) are pulsed or otherwise modulated at a frequency substantially higher than the response cutoff frequency of a driven analog plant (e.g., a finely positioned mechanical table). The band pass characteristics of the driven analog plant convert the high frequency energy content of the pulses applied to the DAC's input into a smoothed response having a substantially lower frequency (e.g., an essentially DC response). By varying the duty cycle of the high frequency pulses, the system can be controlled to make it appear as if the DAC has a greater number of input bit nodes than it actually has. The analog plant can then be driven with finer resolution than that provided by the limited number of input bit nodes of the DAC.

Method and apparatus for increasing effective resolution of analog output of digital-to-analog converter (DAC) having predetermined digital word size, where DAC drives plant

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Scott Jordan