US3845370A - Credibility testing in sampled-data systems - Google Patents

Credibility testing in sampled-data systems Download PDF

Info

Publication number
US3845370A
US3845370A US00387267A US38726773A US3845370A US 3845370 A US3845370 A US 3845370A US 00387267 A US00387267 A US 00387267A US 38726773 A US38726773 A US 38726773A US 3845370 A US3845370 A US 3845370A
Authority
US
United States
Prior art keywords
feedback
period
network
data
valid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00387267A
Other languages
English (en)
Inventor
J Mantey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US00387267A priority Critical patent/US3845370A/en
Priority to GB2172574A priority patent/GB1463101A/en
Priority to IT23406/74A priority patent/IT1012994B/it
Priority to FR7422156A priority patent/FR2240476B1/fr
Priority to DE2431974A priority patent/DE2431974A1/de
Priority to JP7792474A priority patent/JPS5527681B2/ja
Priority to CA205,109A priority patent/CA1005859A/en
Application granted granted Critical
Publication of US3845370A publication Critical patent/US3845370A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B9/00—Safety arrangements
    • G05B9/02—Safety arrangements electric
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
    • H02P7/2855—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/42—Servomotor, servo controller kind till VSS
    • G05B2219/42293—Regenerate faulty feedback by using previous value, substitute

Definitions

  • FIG. 5 A ACCELERATE consmn DECELERATE SPEED RUN cousmn SPEED ACCELERATE RUN DECELERATE l
  • the present invention pertains to the field of closedloop sampled-data servomechanisms for use in controlling a process.
  • the present invention pertains to closed loop motor speed servomechanisms which de rive aperiodic speed feedback samples from a digital transducer driven by the motor being controlled.
  • An inherent characteristic of a sampled-data servomechanism is that a control decision is made at one sample time and. as a result ofthis decision. a mode of process control is instituted. and then maintained, in essentially open loop fashion. until a subsequent sample time. At this subsequent sample time, new feedback information is available and the mode of process control is updated.
  • the present invention operates upon the principle that whatever the mode of process control. the range of possible subsequent feedback samples can be predicted. If the subsequent feedback sample does not fall within this range. the particular sample is not credible and is classified as invalid. Rather than use the invalid sample to effect a change in the mode of process control. hoping that the invalid sample at least shows the trend in a process variable and any resulting overcorrection will appear in subsequent valid samples. the present invention discards the invalid sample and substitutes a sample based upon the most recent prior valid sample or samples.
  • the present invention provides a testing network or window which tests each feedback sample. Since the validity of a feedback sample is a function of the sample rate and may be variable with other process parameters. the window of acceptable parameter limits is variable with time and may be variable with other process parameters. In one embodiment. the arrival of each valid feedback sample is effective to reset the testing network. in anticipation of the need to test the subsequent feedback sample.
  • the present invention provides the simple control technique of testing the feedback information for validity. and then using the information if it passes the test. or. alternatively. making a substitution based upon the most recent valid feedback ifthe current feedback fails to pass the test.
  • FIG. I is a schematic showing of the invention applied to process control
  • FIG. 2 is a graph showing the operation of FIG. l's process variable window.
  • FIG. 3 is a schematic showing of the invention applied to a speed control process for a direct current motor
  • FIG. 4 is a graph showing the contents of FIG. 3s speed memory or store. whose contents define the desired tachometer period. i.e.. motor speed. for a startrun-stop sequence. and also showing the acceptable period window. i.e.. valid feedback information. which will be accepted and used in the closed-loop feedback system; and
  • FIG. 5 is a graph showing the contents of FIG. 4s speed command network.
  • process [0 is generally shown as having a process variable controller II. a sampled-data first process variable sensor 12, and a second process variable sensor 17.
  • This general showing of a controllable process is meant to embody a large variety of processes. such as the speed control process of FIG. 3. or. for example. a temperature control process wherein controller 1] compares the output of sensor 12 to a set point temperature and controls the temperature of the process to the magnitude defined by this set point.
  • controller ll The control set point or command for process 10 is received by controller ll by way of conductor 13.
  • Actual process variable information. corresponding to the set point characteristic. is received by controller ll by way of conductor l4.
  • Controller I1 is constructed and arranged to compare the command variable magnitude on conductor 13 with the actual variable magnitude on conductor 14 and to institute corrective action within process 10 in order to bring the magnitude of the process variable. for example temperature. to the command magnitude.
  • Sensor 12 operates to periodically or aperiodically sample the actual magnitude of the process variable and to supply sampled-data feedback on condutctor 15 to process variable window network 16.
  • Network l6 operates to compare the magnitude of each individual feedback sample to a reference magnitude and to make a decision as to whether or not the particular feedback sample is a valid feedback sample or an invalid feedback sample.
  • a valid feedback sample is a feedback sample which falls within the range of expected values. This range is defined by the extent to which controller ll can achieve change in the process variable. This change is always dependent upon the time between feedback samples. and may additionally be responsive to a second process variable. When the expected range of feedback magnitudes is in fact responsive to and variable with a second process variable.
  • a second process variable sensor 17 is associated with process It) and provides an output on conductor l8 to control the testing parameter utilized by network 16 to test feedback 15.
  • this sample is provided as valid feedback information on conductor 19.
  • This valid feedback sample is stored in last valid feedback memory network 20 and is additionally applied to conductor 14 to be used as current feedback information by controller II.
  • valid feedback information is effective to reset window network l6. by way ofconductor 21. preparing this network for a subsequent feedback sample. Since the ability of network 16 to test a given feedback sample is time dependent. it is necessary to reset this network to a zero time state such that its testing parameter may again begin its time dependent variation. awaiting a subsequent feedback sample.
  • network 20 may be a register which holds the last valid feedback in binary form. in addition. the output of network 20. which will be used only if subsequent feedback samples fail to pass the test imposed by network 16. may be a substitution which is based upon a most recent prior valid sample or samples. For example. this substituted signal may be a valid sample whose magnitude decays with time.
  • This mode of process control continues until a valid feedback sample is obtained from sensor l2.
  • this valid feedback sample is obtained. it is stored in memory network 20. it is supplied to conductor 14 for use by controller. and window network 16 is reset to its zero time state. awaiting the next feedback sample.
  • FIG. 2 is a graph showing schematically the operation of window network 16.
  • a nominal ex-' pected feedback magnitude is represented by broken line 30.
  • window network [6 is reset to its Yero time state wherein the window test to be subsequently instituted by network 16 is defined by solid lines 3t and 32.
  • curve 31 defines the magnitude of the process variable sensed by sensor 12 if controller ll institutes a lOt) percent ON control of the condition changing portion of process 10 at time t0. This in a temperature control process. for example. would constitute maximum energization of an associated heater. or in a speed control process. would institute full energization of a motor.
  • Curve 32 defines the expected feedback which can occur with variation in time if controller ll institutes a ltlt) percent OFF condition of the condition changing portion of process 10 at time it]. lt is known that valid feedback information must exist somewhere between curves 3l and 32. Any feedback sample which is either above curve 31 or below curve 32. is invalid feedback information.
  • FIG. 3 is a schematic showing of the present inven tion as applied to a process involving the speed control of direct current motor 40.
  • motor 40 is directly connected to tape drive capstan 4t. associated with magnetic recording tape 42. in this environment it is preferable that motor 40 be a high torque low inertia motor of the type described in U.S. Pat. No. 3.490.672. issued to G. A. Fisher and H. E. Van Winkle.
  • the feedback sensor in this process is a digital tachometer 43.
  • a digital tachometer 43 provides a feedback pulse on conductor 44 for each unit of rotation of motor 40.
  • tachometer 43 may provide 500 pulses for each revolution of motor 40.
  • period measurement network 45 This network is effective to count the number of cycles of high frequency clock 46 which occur between adjacent output pulses from tachometer 43. Network utilizes these two inputs to derive a tachometer period measurement. T. on conductor 46.
  • Capstan motor 40 operates in a start/stop mode and the apparatus of FIG. 3 is operable to control the speed of this motor during acceleration. constant speed run and deceleration of the motor.
  • Speed memory network 47 contains a stored memory of the desired tachometer period. Tr. which should occur during these three pha ses ofa motor cycle.
  • this network contains a stored memory of the acceptable deviation from this desired tachometer period. this deviation being defined as the acceptable period window ATr.
  • HO. 4 shows a representative content of memory 47 wherein solid line 62 represents the desired tachometer period Tr. or command set point for the motors accelerate. constant speed run. and decelerate intervals.
  • the AT range defined by broken lines 63 and 64 defines the acceptable period window ATr. At any given time. the actual period measurement. T. supplied by network 45. must fall within the bounds of broken lines 63 and 64 in order to be classified as valid feedback information.
  • Period comparison network 51 and period testing network 68 are effective to compare the period feedback information T on conductor 46 with the desired tachometer period information Tr received from mem ory 47 by way of conductor 52. and with the acceptable period window information Tr received from memory 47 by way of conductor 53 to determine if the feedback information is valid and. if valid. to compute the period error Te for use to control the speed of motor 40.
  • network 68 compares the actual period T to the desired period Tr to determine if the difference between these two periods is less than the acceptable period window.
  • Network 68 may. for example. be an arithmetic and logic unit controlled to perform the test lT-Trl ATr. in other words. equation lT-Trl ATr must be satisfied. lfthis test is passed.
  • network 51 is enabled by way of conductor 69.
  • This hold network may provide a steady magnitude signal to output conductor 61.
  • network may include a register holding the binary value of Te. the register driving a bipolar digital to analog converter whose output comprises conductor 6
  • this signal magnitude or output may exponentially decay toward the expected subsequent period error by providing the predictor network described in US. Pat. No. 3.758.757. by O. R. Buhler and J. T. Cutter.
  • the apparatus of FIG. 3 includes a speed command network 56 which is controlled by a start command on conductor 57 and a stop command on conductor 58 to provide a signal to power amplifier 59.
  • This signal is selected to normally energize motor to cause the motor to follow a desired acceleration. constant speed run and deceleration profile.
  • the output of network 56 appears on conductor 60 and is summed with the output of network 55 to variably control the energization of motor 40. For example. if the particular feedback sample derived from network indicates that the motor is slow. the output of network 61 is effective to add to the signal provided by conductor 60 and to thereby increase the encrgization of motor 40. On the other hand. should the motor be fast. the output of network 55 is effective to subtract from the output of network 56 and thereby decrease the energization of motor 40.
  • FIG. 5 shows the contents of speed command network 56 for the accelerate. constant speed run, and decelerate intervals of the motor.
  • the magnitude of curve 65 is representative of the degree of motor energization which will usually achieve the desired speed profile for a start/stop cycle of motor 40.
  • a closed-loop speed control servomechanism operable to variably energize a motor in a start-run-stop sequence to achieve a desired acceleration, constant speed run and deceleration profile. comprising:
  • digital tachometer means driven by said motor and operable to provide sampleddata period feedback data in accordance with actual motor speed, said feedback data being aperiodic during acceleration and deceleration, and being substantially periodic during constant speed run,
  • period testing network means receiving as inputs said period feedback. said desired period data and permissible period window data. and operating thereon to test said feedback data against a permissible period window data to determine if said feedback data is valid or invalid, hold network means controlled by said testing network means when said feedback data is valid and operable to hold said valid feedback data.
  • said hold network means operable to selectively supply current valid feedback data or to substitute therefor feedback data which is a function of prior valid feedback data for use by said servomechanism, in accordance with said current feedback data passing or failing said test. respec tively.
  • the servomechanism as defined in claim 1 including period comparison network means controlled by said period testing network and receiving as inputs said period feedback data and said desired period data. and operable to supply only valid feedback data to said hold network means. and means connecting the contents of said hold network for use by said servomechanism.
  • the servomechanism as defined in claim 2 including command speed network means. and means summing the output of said command speed network means with the contents of said hold network means.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Power Engineering (AREA)
  • Control Of Electric Motors In General (AREA)
  • Feedback Control In General (AREA)
  • Control Of Velocity Or Acceleration (AREA)
  • Testing And Monitoring For Control Systems (AREA)
  • Safety Devices In Control Systems (AREA)
US00387267A 1973-08-10 1973-08-10 Credibility testing in sampled-data systems Expired - Lifetime US3845370A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US00387267A US3845370A (en) 1973-08-10 1973-08-10 Credibility testing in sampled-data systems
GB2172574A GB1463101A (en) 1973-08-10 1974-05-16 Closed-loop system control apparatus
IT23406/74A IT1012994B (it) 1973-08-10 1974-05-31 Servomeccanismo perfezionato
FR7422156A FR2240476B1 (ja) 1973-08-10 1974-06-17
DE2431974A DE2431974A1 (de) 1973-08-10 1974-07-03 Prozessteuerung
JP7792474A JPS5527681B2 (ja) 1973-08-10 1974-07-09
CA205,109A CA1005859A (en) 1973-08-10 1974-07-17 Credibility testing in sampled-data systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00387267A US3845370A (en) 1973-08-10 1973-08-10 Credibility testing in sampled-data systems

Publications (1)

Publication Number Publication Date
US3845370A true US3845370A (en) 1974-10-29

Family

ID=23529162

Family Applications (1)

Application Number Title Priority Date Filing Date
US00387267A Expired - Lifetime US3845370A (en) 1973-08-10 1973-08-10 Credibility testing in sampled-data systems

Country Status (7)

Country Link
US (1) US3845370A (ja)
JP (1) JPS5527681B2 (ja)
CA (1) CA1005859A (ja)
DE (1) DE2431974A1 (ja)
FR (1) FR2240476B1 (ja)
GB (1) GB1463101A (ja)
IT (1) IT1012994B (ja)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2330055A1 (fr) * 1975-10-31 1977-05-27 Hagenuk Neufeldt Kuhnke Gmbh Limiteur de dispositifs de mesure de grandeurs reglees
US4216419A (en) * 1977-10-24 1980-08-05 U.S. Philips Corporation Tachometer system
EP0110325A1 (en) * 1982-11-26 1984-06-13 Fujikin International, Inc. Flow rate control system
USRE32102E (en) * 1976-04-19 1986-04-01 Acrison, Inc. Weigh feeding apparatus
EP0177683A2 (de) * 1984-10-10 1986-04-16 UTP - Schweissmaterial GmbH & Co. Verfahren zur Drehzahlregelung von Gleichstrommotoren
DE3739244A1 (de) * 1986-11-19 1988-06-01 Honda Motor Co Ltd Ladedruck-steuerverfahren
US4775949A (en) * 1986-06-27 1988-10-04 K-Tron International, Inc. Weigh feeding system with stochastic control
US4893262A (en) * 1986-06-27 1990-01-09 K-Tron International, Inc. Weigh feeding system with self-tuning stochastic control
US4954975A (en) * 1988-08-10 1990-09-04 K-Tron International, Inc. Weigh feeding system with self-tuning stochastic control and weight and actuator measurements
WO1991018334A1 (de) * 1990-05-22 1991-11-28 Siemens Aktiengesellschaft Verfahren zum betrieb eines lagemessystems
EP0541326A2 (en) * 1991-11-04 1993-05-12 General Electric Company Determination of control system status
EP1096343A3 (en) * 1999-10-12 2002-11-20 Visteon Global Technologies, Inc. Method and apparatus providing operation of an integration hub for automotive signals during low voltage conditions
US20090259340A1 (en) * 2008-04-15 2009-10-15 Olympus Medical Systems Corp. Manipulator and method of controlling manipulator

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5284152A (en) * 1976-01-07 1977-07-13 Nippon Kokan Kk Method of controlling continuous rolling machine
JPS5882316A (ja) * 1981-11-10 1983-05-17 Kubota Ltd 刈取収穫機の自動刈高さ制御装置
DE4302085C1 (de) * 1993-01-21 1994-07-21 Ihde Stefan Verfahren zum Dosieren und Mischen von aus mehreren Komponenten bestehenden Zahnfüllstoffen und Einrichtung zur Durchführung des Verfahrens

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3356921A (en) * 1964-04-24 1967-12-05 Minnesota Mining & Mfg Motor control circuit with compensation for dropout of control signals
US3790874A (en) * 1972-07-27 1974-02-05 Cleveland Machine Controls Motor drive control system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3356921A (en) * 1964-04-24 1967-12-05 Minnesota Mining & Mfg Motor control circuit with compensation for dropout of control signals
US3790874A (en) * 1972-07-27 1974-02-05 Cleveland Machine Controls Motor drive control system

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2330055A1 (fr) * 1975-10-31 1977-05-27 Hagenuk Neufeldt Kuhnke Gmbh Limiteur de dispositifs de mesure de grandeurs reglees
USRE32102E (en) * 1976-04-19 1986-04-01 Acrison, Inc. Weigh feeding apparatus
US4216419A (en) * 1977-10-24 1980-08-05 U.S. Philips Corporation Tachometer system
EP0110325A1 (en) * 1982-11-26 1984-06-13 Fujikin International, Inc. Flow rate control system
EP0177683A2 (de) * 1984-10-10 1986-04-16 UTP - Schweissmaterial GmbH & Co. Verfahren zur Drehzahlregelung von Gleichstrommotoren
EP0177683A3 (de) * 1984-10-10 1987-08-26 UTP - Schweissmaterial GmbH & Co. Verfahren zur Drehzahlregelung von Gleichstrommotoren
US4893262A (en) * 1986-06-27 1990-01-09 K-Tron International, Inc. Weigh feeding system with self-tuning stochastic control
US4775949A (en) * 1986-06-27 1988-10-04 K-Tron International, Inc. Weigh feeding system with stochastic control
DE3739244A1 (de) * 1986-11-19 1988-06-01 Honda Motor Co Ltd Ladedruck-steuerverfahren
US4954975A (en) * 1988-08-10 1990-09-04 K-Tron International, Inc. Weigh feeding system with self-tuning stochastic control and weight and actuator measurements
WO1991018334A1 (de) * 1990-05-22 1991-11-28 Siemens Aktiengesellschaft Verfahren zum betrieb eines lagemessystems
EP0541326A2 (en) * 1991-11-04 1993-05-12 General Electric Company Determination of control system status
EP0541326A3 (en) * 1991-11-04 1993-06-09 General Electric Company Determination of control system status
EP1096343A3 (en) * 1999-10-12 2002-11-20 Visteon Global Technologies, Inc. Method and apparatus providing operation of an integration hub for automotive signals during low voltage conditions
US20090259340A1 (en) * 2008-04-15 2009-10-15 Olympus Medical Systems Corp. Manipulator and method of controlling manipulator
EP2110212A3 (en) * 2008-04-15 2010-12-29 Olympus Medical Systems Corp. Manipulator
US8019473B2 (en) 2008-04-15 2011-09-13 Olympus Medical Systems Corp. Manipulator and method of controlling manipulator

Also Published As

Publication number Publication date
IT1012994B (it) 1977-03-10
DE2431974A1 (de) 1975-02-20
GB1463101A (en) 1977-02-02
FR2240476A1 (ja) 1975-03-07
JPS5037982A (ja) 1975-04-09
JPS5527681B2 (ja) 1980-07-22
FR2240476B1 (ja) 1977-06-24
CA1005859A (en) 1977-02-22

Similar Documents

Publication Publication Date Title
US3845370A (en) Credibility testing in sampled-data systems
US4609855A (en) Adaptive servomotor control
US3731176A (en) Deceleration and stop-lock motor control apparatus
EP0157191B1 (en) Method and apparatus for measuring velocity and position in servo system
US3731177A (en) Disc file head movement control system
US4851755A (en) Low power stepper motor drive system and method
US3206665A (en) Digital speed controller
US3836833A (en) Adaptive motor acceleration
US4777609A (en) Print head motor control system having steady state velocity compensation
US4775945A (en) Print head motor control system with automatic drive parameter calculations
US3629560A (en) Apparatus for controlled deceleration in numerical positioning
US4134106A (en) Absolute resolver angle to digital converter circuit
US3826964A (en) Digital servo controller
US4283715A (en) Control of display devices with electromagnetic drums
US3619757A (en) Variable speed closed loop digital servosystem
US4420715A (en) Apparatus for controlling motor speed
US4507592A (en) Microprocessor controlled tape capstan
US3835360A (en) Numerical control system
US4540920A (en) Relating to tape transport control systems
US3786333A (en) Digital regulating control for servo system
US3758757A (en) Exponential predictor and sampled-data systems
US4484137A (en) Wide dynamic range shaft speed sensor
US3644815A (en) Digital p.i. servocontrol system
US4494711A (en) Dual mode control system for controlling tape position in a reel to reel transport apparatus
US3465223A (en) Speed measuring system