GB2041576A - Electric drive unit control apparatus - Google Patents
Electric drive unit control apparatus Download PDFInfo
- Publication number
- GB2041576A GB2041576A GB8000626A GB8000626A GB2041576A GB 2041576 A GB2041576 A GB 2041576A GB 8000626 A GB8000626 A GB 8000626A GB 8000626 A GB8000626 A GB 8000626A GB 2041576 A GB2041576 A GB 2041576A
- Authority
- GB
- United Kingdom
- Prior art keywords
- drive unit
- register
- change
- contents
- digital control
- 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.)
- Withdrawn
Links
- 230000000737 periodic effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims 1
- 238000000034 method Methods 0.000 description 4
- 235000001270 Allium sibiricum Nutrition 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
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
- G05B15/00—Systems controlled by a computer
- G05B15/02—Systems controlled by a computer electric
-
- 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
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/19—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
- G05B19/33—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path using an analogue measuring device
- G05B19/35—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path using an analogue measuring device for point-to-point control
- G05B19/351—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path using an analogue measuring device for point-to-point control the positional error is used to control continuously the servomotor according to its magnitude
Abstract
The apparatus changes the position of a drive unit 18 in accordance with desired changes periodically provided as a digital value and entered in a first register 30, which is then decremented to zero by counting actual increments of drive unit change. Power to change the drive unit is proportional to the residual value in the register, with no power when actual change has equalled desired change. The counting of actual change increments is determined from clock pulses updating a second register 60 representing position whenever the analog equivalent of this register differs from an analog signal provided by a position sensor 22 and representing actual position. <IMAGE>
Description
SPECIFICATION
Electric drive unit control apparatus
This invention relates to apparatus for controlling the position of an electric drive unit of a control system in response to digital signals indicative of the required change in drive unit position. The invention makes it possible to use digital signals for regulation of position changes of large drive units which, due to high inertia, have a non-linear relationship between drive unit travel and duration of energizing power.
It has been proposed to position a drive unit in response to digital signals, utilizing the computer which issues the digital signals also to compare the actual position of the drive unit with the desired position. That approach is often found undesirable because of the periodic nature of the feedback of a rapidly changing position. In other known systems, the drive units have frequently been positioned solely in response to the time duration of the signals sent to the drive units, thus resulting in a non-linear response by failing to take into account the nonlinear speed of the drive due to the inertia of the drive unit itself and caused by a variable load on the drive unit.
It is an object of this invention to provide apparatus for making precise changes in drive unit positions in a digital control system so as to overcome the disadvantages of the variable relationship between the time duration of energizing the drive unit and its actual change in position.
According to the present invention, there is provided, apparatus for controlling an electric drive unit in response to digital control signals commanding position changes of the drive unit, comprising a register into which each digital control signal is entered, a circuit arranged to decrement the contents of the register as the drive unit performs the position change, and a power supply circuit for the drive unit arranged to supply power to the drive unit proportional to the contents of the register.
The preferred embodiment of the invention controls the position of the electric drive unit in response to periodically produced digital control signals which are each indicative of the position change required for the drive unit during the ensuing period.
The apparatus includes a first register which re chives the digital control signal indicative of the position change required and changes the magnitude of its stored value accordingly. Means are provided for supplying power to the drive unit in an amount proportional to the stored value in the first register so as to move the drive unit in a direction and by an amount corresponding respectively to the sign and magnitude of that stored value. Means are also provided for producing an ananlog signal representing the actual position of the drive unit. A second register is provided for storing a signal indicative of the position of the drive unit. The contents of the second register is utilized through a digital to analog converter to produce an analog signal representing the position of the drive unit.The ananlog signal from the digital to analog converter is compared with the actual position signal and the output of the comparator operates a gate means which is operable to gate clock signals from a clock source to step the first and second registers until the analog signal from the converter corresponds with the actual position signal, thus up-dating the first and second registers so that the contents of the first register represents the change in position which has not yet been effected by the drive unit arid the contents of the second register represents the existing position of the drive unit. Until the contents of the first register are brought to zero, power is modulated to the drive unit. Thus the actual change in drive unit position is made in accordance with the digital control signal received.
The sole Figure of the accompanying drawing is a block diagram of a digital drive unit apparatus constituting the preferred embodiment of this invention.
In the drawing, a digital control computer 10 receives on line 12 an input from the process being controlled and produces on an external bus 14 digital signals indicative of the change in position required for the drive unit during the period between consecutive calculations of that change value. The computer 10 may utilize as one input digital signals from lines 16 representing the existing position of the drive unit, namely drive unit 18 which may be used in the data base. However, the signals on line 16 are not required for establishing drive unit position.
In the Figure the drive unit 18 is shown as an electric motor which is effective by way of a mechanical coupling 20 to change the position of a position sensor 22 as well as the position of a valve 24. The valve 24 may, for example, control the flow of a process fluid in a pipe 26 so as to modify the input to the process which affects the variable being measured and controlled, i.e. the variable transmitted to the computer over line 12.
The position sensor 22 may, for example, be a slidewire with a tap wherein the relationship of the tap to the slidewire is determined by the position of the shaft 20 of the drive unit motor 18. Such a position sensor will then produce on line 28 an analog signal in the form of a voltage, for example, which is continuously representative of the actual position of the drive unit. The position sensor may, of course, be any one of a number of other types of sensors as may be desired for the type of service involved.
The digital value on the bus 14 which is supplied as the input to the drive unit error register 30 is added to any remnant value in that register so that the stored value corresponds to the change in position called for by the last signals provided over lines 14 plus any remaining magnitude stored in that register from the previous change signals. Thus, the register provides on its output lines 32 a digital signal representing the total change in drive unit position which has been required by the computer 10 but which has not yet been effected by a change in position of the drive unit 18.
So long as the digital signals provided on lines 32 supply to the pulse modulating logic 34 an input which is other than zero, a signal is produced which will cause the drive unit to move in that direction which tends to reduce the input to zero. There is therefore provided by modulating logic 34 an output on either line 36 or line 38 to the output logic 40 indicating respectively either an increase or decrease requirement in the opening of the valve 24 and hence either a clockwise or anticlockwise rota tion, for example, of the drive unit 18.The signals which appear on either line 36 or 38 depend upon the polarity or sense of the change in drive unit position required and are processed in the output logic of block 40 to produce either on line 42 or line 44 signals to the power switch 48 which will be effective respectively to provide an output either on line 50 or 52 to energise the drive unit motor 18 for rotation in one direction or the other. For example, a signal on line 42 may cause the power switch to provide a pulse on line 50 into drive unit 18 which will produce clockwise rotation of the shaft 20 of the drive unit 18 whereas a comparable signal on line 44 instead of line 42 will be effective by way of the power switch 48 to provide a pulse of similar magnitude on line 52 to produce an equal anticlockwise rotation of the drive unit.
The pulse modulating logic which accepts the digital signal from the line 32 and produces outputs on line 36 or 38, depending upon the direction of position change required, may be made up of any of a number of circuits. For example, there may be utilized a ramp generator for generating a ramp signal over the duty cycle period established for the drive unit. The magnitude of that ramp signal may be compared with the magnitude of the drive unit error obtained from the lines 32 as, for example, by a digital comparator. A pulse may be started at the beginning of the ramp and terminated when the ramped signal equals the error signal so that the duration of the pulse produced in each duty cycle is proportional to the magnitude of the error signal from lines 32.Thus, there will be produced either on line 36 or line 38 for each duty cycle of the drive unit a pulse of duration corresponding to the magnitude of the change in position represented by the stored value in register 30. That pulse is effective in the output logic to provide a similar pulse on a corresponding output line 42 or 44 for operation of the power switch 48. The output logic also may, for example, include limit circuits or manual control logic, as required.
The signals on lines 42 and 44, as previously mentioned, initiate the application of the necessary power to either line 50 or 52. Forthis purpose the power switch 48 may, for example, be a solid state switching network which is controlled by the signals on lines 42 and 44.
In order to update the drive unit error register 30 as well as the position register 60, pulses are required on lines 62 and 64 such that each pulse represents an increment of position change for the drive unit 18, with that increment corresponding to the least significant digit in the register 30.
To produce the updating pulses provided on lines 62 and 64, the analog signal which appears on line 28 representing the actual position of the drive unit 18 is compared in a comparator 68 with the signal which is produced on a line 70 by a digital to analog converter 72 in accordance with the value stored in the position register 60 and read out of that position register over lines 74 as an input to the converter.
When the signal on line 28 differs from the signal on line 70, the comparator 68 produces a signal on its output line 78 to gating logic 80 which is effective to gate the output of a clock source 82 through the gating logic 80 to the lines 62 and 64 so that, by virtue of the clock signal gated to line 62, there is a resulting decrementing of the register 30 and by virtue of the clock signal gated to line 64, there is either an incrementing ordecrementing of the contents of the position register 60 depending on the direction of the position change of the drive unit.
When the signal on line 70 representing the position measurement is equal to the signal on line 38 representing actual drive unit position, there is neither incrementing or decrementing of the register 30. Thus the number of incremental pulses on lines 62 and 64 represent the actual change in drive unit position.
Therefore, any change in position of the drive unit 18 as a result of operation of the power switch 48 which is effective to produce a difference between the position sensed by position sensor 22 and the position stored in the position register 60 is effective to step the register 30 so as to decrement the value stored in that register while it increments or decrements and therefore updates the value stored in the position register 60 so as to cause that value to correspond with the position sensed by the position sensor 22. The position register 60 can therefore provide over lines 16 to the digital process controller 10 signals indicative of the existing position of drive unit 18 with the signal provided being in the digital form required by the digital computer.However these signals on line 16 are not a requirement for establishing the drive unit position change in accordance with that called for by the computer.
It will be evident from the above description that, over the number of duty cycles of the drive unit 17 which occur for each of the periodic outputs from the computer over line 14, there is produced a pulse input to the drive unit 18 for energizing it in an appropriate direction with the magnitude of each pulse corresponding to the magnitude stored in the register 30. As the drive unit 18 changes it position, causing a corresponding decrementing of the register contents in register 30, the duration of the pulses diminishes in view of the lower value of the contents of register 30 until the drive unit 18 has assumed the desired position, namely when the contents of register 30 are zero. This results in an actual drive unit position change, as represented by the number of decrements of register 30, exactly equaling the required position change which has initially been placed in register 30 from the computer on the bus 14.
Claims (7)
1. Apparatus for controlling an electric drive unit in response to digital control signals commanding position changes of the drive unit, comprising a register into which each digital control signal is entered, a circuit arranged to decrement the contents of the register as the drive unit performs the position change, and a power supply circuit for the drive unit arranged to supply power to the drive unit proportional to the contents of the register.
2. Apparatus according to claim 1, wherein each digital control signal is added algebraically to any value remaining in the register when the digital control signal is provided.
3. Apparatus according to claim 1 or 2, wherein the digital control signals are provided in a periodic manner.
4. Apparatus according to claim 1, 2 or 3, wherein the power supply circuit provides pulses to the drive unit having a duration proportional to the contents of the register.
5. Apparatus according to claim 1,2,3 or 4, wherein the decrementing circuit comprises a follow-up circuit with a second register whose contents represent the position of the drive unit, and wherein pulses applied to the second register to make its contents follow the position of the drive unit are also applied to the first said register to effect the decrementing thereof.
6. Apparatus according to claim 5, wherein the follow-up circuit comprises a position sensor providing an analogue signal representing the position of the drive unit, a digital-to-analogue converter connected to the second register and a comparator circuit arranged to gate pulses to the registers when the analogue signal and the output of the converter differ.
7. Apparatus for controllinr 1l electric drive unit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/214,617 US4374351A (en) | 1980-01-09 | 1980-12-09 | Digital drive unit regulator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US868079A | 1979-02-02 | 1979-02-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2041576A true GB2041576A (en) | 1980-09-10 |
Family
ID=21733057
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8000626A Withdrawn GB2041576A (en) | 1979-02-02 | 1980-01-09 | Electric drive unit control apparatus |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS55103606A (en) |
| DE (1) | DE3002835A1 (en) |
| FR (1) | FR2448178A1 (en) |
| GB (1) | GB2041576A (en) |
| IT (1) | IT1129609B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2151372A (en) * | 1983-11-10 | 1985-07-17 | Canon Kk | Control of shutter position |
| US4675490A (en) * | 1981-06-25 | 1987-06-23 | Fanuc Limited | Method and apparatus for controlling electrode position in an electric discharge machine by counting feedback pulses and repeatedly adding the count |
| EP0566025A1 (en) * | 1992-04-13 | 1993-10-20 | Fichtel & Sachs AG | Control device for an actuator |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3120691A1 (en) * | 1981-05-23 | 1982-12-16 | Teldix Gmbh, 6900 Heidelberg | Magnetic bearing |
| US4554496A (en) * | 1983-02-25 | 1985-11-19 | Johnson Service Company | Controllable rotary actuator |
| JP2971899B2 (en) * | 1990-02-14 | 1999-11-08 | 旭光学工業株式会社 | Zoom lens barrel |
| DE19707171A1 (en) * | 1997-02-22 | 1998-08-27 | Valeo Klimasysteme Gmbh | Actuator control |
-
1980
- 1980-01-09 GB GB8000626A patent/GB2041576A/en not_active Withdrawn
- 1980-01-26 DE DE19803002835 patent/DE3002835A1/en not_active Withdrawn
- 1980-01-30 JP JP887980A patent/JPS55103606A/en active Pending
- 1980-01-31 FR FR8002109A patent/FR2448178A1/en active Granted
- 1980-02-01 IT IT19640/80A patent/IT1129609B/en active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4675490A (en) * | 1981-06-25 | 1987-06-23 | Fanuc Limited | Method and apparatus for controlling electrode position in an electric discharge machine by counting feedback pulses and repeatedly adding the count |
| GB2151372A (en) * | 1983-11-10 | 1985-07-17 | Canon Kk | Control of shutter position |
| EP0566025A1 (en) * | 1992-04-13 | 1993-10-20 | Fichtel & Sachs AG | Control device for an actuator |
| US5483137A (en) * | 1992-04-13 | 1996-01-09 | Fichtel & Sachs Ag | Control device |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1129609B (en) | 1986-06-11 |
| DE3002835A1 (en) | 1980-08-14 |
| IT8019640A0 (en) | 1980-02-01 |
| FR2448178A1 (en) | 1980-08-29 |
| JPS55103606A (en) | 1980-08-08 |
| FR2448178B3 (en) | 1981-07-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |