EP0088626A2
Expired / Lapsed
EP
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Apparatus for controlling the speed of a rotating body
Assignee: Lanteris Space LLC
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Filing: 1983-03-08
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Granted: —
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Expires: 2003-03-08
Abstract
Abstract A closed-loop system for precisely regulating the speed of an electrically driven rotating body. A tachometer rotor (53) mechanically linked to the rotating body is provided with p "teeth" (55) around its periphery. A sensor (57) produces a pulse signal upon passage of each of these teeth, to generate a cyclic tachometer signal having a frequency p times the frequency of rotation. A tachometer counter (5) counts this signal and produces a single output pulse after every n x p pulses from the sensor, such that the same one of the p teeth is responsible for triggering each of the successive output pulses, and variations in spacing between teeth do not cause variations in the period of the counter output. A high frequency clock (17) is counted by a second counter (14) which transfers its count to a storage register (23) and resets upon each pulse from the tachometer counter (5), such that the count held by the storage register is a continuously updated, highly accurate digital respresentation of the period of the rotating body. A period comparator (39) derives a speed control signal which is proportional to the inverse of the difference between the count and a digital speed command signal representative of the rotational period at the desired rotational speed.
Inventors
- 👤 Fred Nai-Tsang
- 👤 Ernest Wuethrich
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 00:21
CPC Classifications
G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/489; H; H02; H02P; H02P23/00; H02P23/22
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
208 words
Apparatus for controlling the speed of a otating body, comprising tachometer means (57,5) for deriving a periodic electrical pulse signal having a period which is inversely proportional to the rotational frequency of said body (53); free-running counter mea.3 (17) connected to said tachometer means (57,5) for continuously counting at a fixed frequency and accumulating a count throughout each period of said periodic pulse signal, for responding to each said periodic pulse signal by resetting said count to zero, and for continuously producing a digital electrical signal which is a numerical representation of said count at the end of the most rcent period of said periodic pulse signal; means (37) to produce a command digital reference signal representative of the desired rotational speed of said rotating body (53); period comparator means (39) for comparing said digital electrical signal with said digital reference signal and for generating in response to the difference therebetween a speed control signal having a magnitude representative of said difference; speed control means (49) connected to said period comparator means (39) to vary the rotational speed of said rotating body (53) in response to said speed control signal in a sense to continuously minimise said difference between said digital electrical signal and said digital reference signal.
Claim 2
Dependent Claim
208 words
Apparatus for controlling the speed of a otating body, comprising tachometer means (57,5) for deriving a periodic electrical pulse signal having a period which is inversely proportional to the rotational frequency of said body (53); free-running counter mea.3 (17) connected to said tachometer means (57,5) for continuously counting at a fixed frequency and accumulating a count throughout each period of said periodic pulse signal, for responding to each said periodic pulse signal by resetting said count to zero, and for continuously producing a digital electrical signal which is a numerical representation of said count at the end of the most rcent period of said periodic pulse signal; means (37) to produce a command digital reference signal representative of the desired rotational speed of said rotating body (53); period comparator means (39) for comparing said digital electrical signal with said digital reference signal and for generating in response to the difference therebetween a speed control signal having a magnitude representative of said difference; speed control means (49) connected to said period comparator means (39) to vary the rotational speed of said rotating body (53) in response to said speed control signal in a sense to continuously minimise said difference between said digital electrical signal and said digital reference signal.
Claim 3
Dependent Claim
36 words
The apparatus of Claim 1, wherein said tachometer means comprises tachometer signal generating means (57) for generating a tachometer signal at a frequency which is an integral multiple of the rotational frequency of said rotating body.
Claim 4
Dependent Claim
48 words
The apparatus of Claim 2, wherein said tachometer means comprises tachometer counter means (5) connected to said tachometer signal generating means (57) and producing in response to said tachometer signal said periodic pulse having a period which is an integral multiple of the period of said tachometer signal.
Claim 5
Dependent Claim
80 words
The apparatus of Claim 1, wherein said tachometer means comprises a tachometer rotor (53) mechanically coupled to said rotating body for synchronous rotation therewith, and a tachometer sensor (57) adjacent and in close proximity to the periphery of said rotor, said rotor having a plurality of sensible poles (55) periodically spaced about the periphery thereof, said tachometer sensor (57) having sensing means therewithin to respond to the passage of each said sensible pole by producing a corresponding electrical output pulse.
Claim 6
Dependent Claim
126 words
The apparatus of claim 4, wherein the tachometer rotor (53) has p sensible poles substantially equispaced about the periphery thereof; the tachometer sensor means (57) produces a cyclic electrical signal having a frequency p times the rotational frequency of said rotating body, a counter means (5) is connected to said sensor means (57) to count the cycles of said cyclic electrical signal and to produce an output periodic electrical pulse signal for each n x p cycles of input signal, where n is an integer; whereby the successive output pulse signals are produced in response to the passage by the sensor of the same one of the p poles, and variations in interpole spacing do not cause variations in the frequency of the output pulse signal.
Claim 7
Independent Claim
36 words
The apparatus of any preceding claim, wherein said free-running counter means includes a free-running, fixed frequency clock signal generator (17) and a numerical counter (14) connected to said clock signal generator to count the cycles thereof.
Claim 8
Independent Claim
31 words
The apparatus of any preceding claim, wherein said free-running counter means includes a buffer gister (23) for storing said count at the end of each period of said periodic pulse signal.
Claim 9
Dependent Claim
53 words
The apparatus of Claim 7, wherein said counter means comprises transfer and reset means (9) connected to receive said periodic electrical pulse signal and to respond thereto by: (1) causing said count to be transferred to said buffer register, and (2) causing said counter means to be reset to a preset =nitial condition.
Claim 10
Independent Claim
36 words
The apparatus of any preceding claim, wherein said counter means includes counter overflow detector means (19) to detect counter overflow and, in response thereto, to transmit an underspeed digital electrical signal to said comparator means (39).
Claim 11
Independent Claim
72 words
The apparatus of any preceding claim, wherein said period comparator means comprises a first register (31) for storing said digital electrical signal, a second register (35) for storing said digital reference signal, an arithmetic-and-logical means (39) for comparing said digital electrical signal with said digital reference signal to produce a digital error signal, and a digital-to-analogue converter means (42) to produce said speed control signal in response to said digital error signal.
References Cited (Backward Citations)
No citation records indexed.
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