Oscillators – Automatic frequency stabilization using a phase or frequency... – Particular error voltage control
Reexamination Certificate
2000-12-19
2004-04-20
Kinkead, Arnold (Department: 2817)
Oscillators
Automatic frequency stabilization using a phase or frequency...
Particular error voltage control
C331S00100A, C331S025000, C700S014000, C700S028000, C700S031000, C700S044000, C700S045000
Reexamination Certificate
active
06724264
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for changing the characteristics of a variety of devices of different scales, fields, types and so on such as plants, apparatus, microcomponents, circuits, circuit elements and so on.
Conventionally, a method of changing the characteristics of a device such as an electric circuit, an electronic circuit or the like, typically involves changing circuit constants or parameters such as resistance R, capacitance C and inductance L, changing the locations of circuit elements such as R, C, L within a circuit, or changing the entire configuration of the circuit. Such changes added to the device causes a change in the transfer function of the associated circuit, and consequently a change in an input/output response of the entire device such as time response and frequency response, and other arbitrary characteristics. Such a method provides an electric/electronic circuit having a response suitable for a particular target such as different control targets or a constant-desired-value control.
It should be noted herein that in this disclosure, the term “device” encompasses any devices which include a variety of apparatus of different scales such as plants, equipment, microcomponents, circuits, circuit elements and so on; apparatus for use in different fields such as electric, chemical, mechanical, physical fields, and apparatus of different types. Also, the “device” includes a “plant” or a “controlled object” which is so called in the field of control engineering.
In respect to a change in certain characteristic of a device, the time response characteristic of a control system will be described below by way of example with reference to FIGS.
31
(
a
) to
31
(
d
). The graphs in FIGS.
31
(
a
) to
31
(
d
) are described mathematically, and are not limited to any particular target. Possible controlled objects may span in a wide range of fields including, but not limited to, a positional (angular) control for a robot arm; a voltage control for a power supply regulator; a speed control for a bullet train; and so on. For example, disturbance is called “jitter” in an application to frequency tracking, while disturbance is called “ripple” in a power supply regulator. In this way, different expressions may be used for the same concept of control in different fields.
FIG.
31
(
a
) shows that an excessively high sensitivity for a better initial response results in oscillations and high susceptibility to disturbance if a certain desired value is given for control. On the other hand, FIG.
31
(
b
) shows that a lower sensitivity for suppressing disturbance results in a slower initial response. In this way, the sensitivity and disturbance suppression characteristics are different control targets and contradictory to each other. Conventionally, as shown in FIG.
31
(
c
), while an attempt is made to find a control point which satisfies both of the characteristics by appropriately adjusting them, this generally results in employment of an unsatisfactory control point which is a compromise for both of the characteristics. More specifically, a control system which exhibits a relatively slow initial response and a relatively high susceptibility to disturbance is typically employed. A conventional adaptive control is intended to achieve the characteristics closest possible to those as illustrated in FIG.
31
(
d
) by adaptively changing the sensitivity in accordance with a particular condition of a controlled object to simultaneously satisfy contradictory characteristics or control targets (the sensitivity and disturbance suppression characteristics in this example) to the utmost.
Referring now to FIGS.
32
(
a
) and
32
(
b
), the time responses illustrated in FIGS.
31
(
a
)-
31
(
d
) will be described from a viewpoint of the frequency response. Whether the sensitivity (or response) is high or low can be found by examining how long a high range characteristic of a transfer function extends. More specifically, as illustrated in FIG.
32
(
a
), a transfer function (representing the frequency characteristic of a system) exhibiting a high gain to a high frequency range may be created for increasing the sensitivity in order to improve the initial response. Conversely, as illustrated in FIG.
32
(
b
), a transfer function exhibiting a lower gain in a high frequency range may be created for decreasing the sensitivity in order to suppress disturbance. As can be understood from the foregoing, a lower sensitivity in the high frequency range is equivalent to a reduction in gain in the high frequency range. Conventionally, many approaches falling within the foregoing category have been proposed to adjust the high frequency range characteristic without damaging the low frequency characteristic.
A specific example of a device required to address contradictory characteristics may be a phase locked loop (PLL) circuit. The PLL typically comprises a controller for controlling a voltage controlled oscillator (VCO), so that circuit constants, circuit configuration and so on of the controller are manipulated to design the PLL to have desirable follow-up speed, stability and so on of oscillating frequencies. Among a wide variety of PLLs, a “time optimal PLL” is known as an example which pursues the response speed rather than jitter suppression. The time optimal PLL has been published, for example, in an article entitled “Time optimal PLL Using High Speed Null Method” by Kobayashi et al, Transactions of Sensing Instrument Control Engineering Systems Information Computer Ergonomics (SICE), 16-4, pp573-578, 1980.
While the foregoing description has been directed particularly to a typical problem in the prior art on a control system including a PLL, similar problems are encountered also in devices such as apparatus of any fields, scales, types and so on which require adjustments of contradictory characteristics, not limited in electric/electronic circuits. For example, similar problems may be encountered in large-scaled plants, electronic apparatus such as computers, electronic devices such as microcomponents, sensors or the like, semiconductor circuits, and so on.
Also, other examples of contradictory characteristics, which require appropriate adjustments, may be resolution and drawing speed, resolution and conversion speed of an A/D converter, and a variety of other paired characteristics, in addition to the aforementioned response speed and disturbance suppression characteristics.
Since the above-mentioned prior art changes the characteristic of a device only using existing design parameters such as circuit constants, circuit configuration, and so on of the “device,” complicated design procedures are often required for further improving the characteristics of the overall device. In addition, the realization of contradictory characteristics inevitably involves a considerable compromise, so that it is quite difficult to actually realize contradictory characteristics simultaneously.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and apparatus for changing the characteristics of devices such as a variety of plants, equipment, circuits, semiconductor devices, and so on in a variety of fields, a variety of scales, a variety of applications, a variety of types, and so on, in a manner different from the prior art.
It is another object of the present invention to provide a method and apparatus for controlling a controlled object in a manner different from the prior art.
It is a further object of the present invention to provide a control method and apparatus which are capable of simultaneously realizing contradictory characteristics such as operation, performance and so on in the prior art.
It is a further object of the present invention to provide a method and apparatus which are capable of improving the characteristics of a device such as the operation and performance more than the prior art.
To achieve the above objects, the present invention employs the concept of time scale in changing the characte
Brady W. James
Kinkead Arnold
Swayze, Jr. W. Daniel
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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