GB2446416A - Zero idle drift sensor voltage measurement potentiometer circuit - Google Patents
Zero idle drift sensor voltage measurement potentiometer circuit Download PDFInfo
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- GB2446416A GB2446416A GB0701132A GB0701132A GB2446416A GB 2446416 A GB2446416 A GB 2446416A GB 0701132 A GB0701132 A GB 0701132A GB 0701132 A GB0701132 A GB 0701132A GB 2446416 A GB2446416 A GB 2446416A
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- 238000005259 measurement Methods 0.000 title abstract 2
- 230000008859 change Effects 0.000 claims abstract description 12
- 230000001351 cycling effect Effects 0.000 claims abstract 2
- 238000004519 manufacturing process Methods 0.000 claims abstract 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/16—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance
- G01D5/165—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying resistance by relative movement of a point of contact or actuation and a resistive track
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R17/00—Measuring arrangements involving comparison with a reference value, e.g. bridge
- G01R17/20—AC or DC potentiometric measuring arrangements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D18/00—Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
Zero idle drift impedance sensor voltage measurement circuit that eliminates output voltage change at the end-points of a potentiometer as the result of physical mechanical wear at ambient and / or extreme temperatures and humidity, and minimises error voltage output between end-points as a result of physical mechanical cycling, and or dithering (over life) at ambient and or extreme temperatures and humidity. The voltages measured at the end points of the potentiometer (V0) and VZt) are independent of the track resistance (Zt) (see equations 5 and 6). The principle beneficiaries of such invention, development and application are automotive sensors. However this invention, development and application applies equally to other manufacturing, scientific, commercial, medical, Industrial and entertainment industries requiring such change critical sensors. Potentiometer, pre-slope resistance, post-slope resistance, track resistance, zero idle drift, beginning of track, end of track.
Description
Zero Idle Drift Circuit for Contact and Non-Contact Sensors The
invention relates to devices for linear and non-linear contact and non-contact sensors. See figure 2.
Sensor Definition: A sensor or transducer is a device, which provides a usable output in response to a specified measurand. The output defines an electrical quantity whilst the physical quantity, property, or condition, which is measured, defines the measurand.
This invention, development and application encompass electromechanical sensors that define the measurand as a rotational or translational displacement or position.
Principle Failure Modes and Causes: Displacement and position sensors used in industry demand stringent accuracy and minimum output change over lifetime. In particular, the automotive and medical industries that strive even more aggressively for change tolerant sensors are migrating from contact sensors (potentiometers) to the more expensive non-contact sensors (Hall and Inductive). The marn reason being the higher than normal failures due to the following; 1. Beginning (Idle) and end of track output drift over lifetime, 2. Excessive slope (linearity and or inter-linearity) change over lifetime, 3. Contact resistance above customer specified thresholds, In the case of the contact potentiometric sensor, failures mentioned above are a result of uncertain resistive ink and wiper (or tag) interface. In essence due to excessive mechanical wear. In the case with contact sensors (potentiometers), mechanical wear (which increases with usage of the sensor) will cause 4. An initial increase of track resistance due to the fresh wiper tip gouging its resistive ink surface. After the wiper has "worn in", a small reduction of track resistance is observed. Here the wiper starts to act as a file on the resistive ink surface and is commonly termed as the burnishing effect.
Finally, there is little track resistance change and the output stabilizes.
5. Build up of ink and wiper debris at the extremes of the wiper stroke. This extreme (in some cases) coincides with the transitional region between resistive ink and its conducting circuit. Any sudden mechanical or electrical hop because of such transition, or debris build up, can result in contact resistance failures.
Failures (I) and (2) caused by (4) is the main practical break through of the invention development and application. An added bonus from practical life tests when comparison is made with conventional sensors; show the Zero Idle Drift Circuit (Termed from here forth as ZID) to suppress failure (3) caused by (5).
Cause of Failure in Standard Circuit: We now outline the basic theory that explains failures (I) and (2) caused by (4) in standard circuits as described shown in figure 2.
For the sake of simplifying the explanation, we will from this point term the impedance as pure resistance. By this, we imply that the imaginary component of the impedance is zero. This invention, application and development will apply also when the imaginary component of the impedance is not zero. With reference to figure 2,4 and 4 are termecJ as the pre and post slope resistors and their values as a ratio of the track resistance Z determine the voltage output as the tag or wiper slides along the track. From Figure 2, the voltage output z5+zx X = Z5 + Z6 + Z, Eqi For 0 <4 4 At the end points
V
-Z5 + Z6 + Z, Eq2 And z5+z' 1= Z5 + Z6 + Z1 Eq3 As track resistance, Z changes (in value) over life due to cause (4), the voltage output at the ends Vo and Vzt also change. This defines the phenomenon of idle drift because in practice we require it not to differ from its value at the beginning of life (0 cycles).
Such a statement can only be true if for a Z is not a function of V0 and V1. We conclude from equations 2 and 3 that the ends change over lifetime usage.
Eliminating Track Drift with ZID Circuit: Solution of the circuit described in figure 1 yield, V2= 2 x (-Z6-Z5)Z +(Z6+ZS)ZIZX+(Z6Z4+Z6Z,+Z5Z4Z, ,Eq4 For 0<4 SZ1.
At the end points vz4z5 0Z6Z4+Z6Z5+Z5Z4 Eq5 V(Z6 Z4)Z3 Eq6 Equations 5 and 6 are independent of Z the track resistance. We thus prove that idle and end of track drift cannot occur in this circuit due to any unavoidable change in Z over lifetime. Q.E.D.
ZU) Circuit: Minimisation of Linearity Error In practice, we define the output voltage as a percentage of the input voltage V such that, vz Vref=IOO-V Eq7 The impedance Zx as the wiper travels across the track, generates an output ranging between V0 to Vz that depends on the material property and geometric dimensions 1. (Xx: the position along the track were Z, is observed, 2. A: Uniform cross-sectional area (m2) of the current travel Thus, Z=Ka,Eq8 Were K = p/A. p (em) is the resistivity of the track along which the wiper travels.
From equations 4, 7 and 8, an output transfer function is determined in terms of position and resistivity (-K2a2+(aK+Z6)Ka+aKZ)Z VIOO (_Z6_Zs)K2a2+(Z6+z5)a,K2a+(z6z4+z6zs ;z4)a,K Eq9 Given the true transfer function Z (Z a+Z a) VTa= 100 (Z6Z4+Z6Z5+Z5Z4)a, ,EqlO Linearity error of the circuit yields, a a+a2a2+a3ct3 a 2 (O I" 2' Eqil Were, a1=-IOOKZ6Z5 a, 2 100 Z6KZ5a,(2Z5+Z6) a3=-l0O Z6KZ5(Z6+z5) = a,2 (Z6 Z4 + Z6 Z5 + Z5 Z4)2 And 1 =cc,2K(Z6 Z5) (Z6Z4+Z6Z5 +Z5Z4) b2-,K(Z6 Z5)(Z6Z4+Z6Z ZZ) In linear systems, we can define the transfer function by defining the first (idle) and last point (end of track) so that 4, Z5 and 4 are related. Thus given an idle (VId,) and end of track point (V), Z4(-V2 + V0) z5= Eq12 And Z4 (V + V0) z6=-Eq13 Thus for any value, 4 there is a single value of Z5 and 4 that satisfies a chosen Vo and V. ZJD Application Example 1: a customer specfl cation for a Linear EGR Sensor is such that, Output Voltage: 5% -95% Linearity: 2.0% Angular Travel. 0 -110 mm Mechanical 5 _ 105 mm Electrical Track Radii (Outer).' 25.2 mm Track Thickness: 4.0 mm Voltage Supply: 5.0 0.1 V Overall Resistance (ROA): 2.2 K Q 40% (Typical) Evaluate linearity error using ZID circuit for Z4=2K2, 41<Q, 8Kg', J6KQ and 32KS?. Assume a 30% resistance increase over l4fetime. Compare ZID circuits with standard linear potentiometric sensor of the same resistivity and dimensions by summarizing difference in absolute linearity error.
For Example I: Ink resistivity p=O.00386 =m. Converting from angular to linear dimensions, L = Track Length = 40.71 mm. Z, = 1964 Q. Figure 3 is the output reference required for Example I Figure 4 is the expected linearity error of the ZID circuit for Z4 = 2K.Q, 41(1), SKQ, I 6Kg) and 32K.Q and show linearity error reducing with increasing Z4.
A 30% increase in track resistance due to mechanical wear implies that Z increases from l964Qto2554Q.
Figure 5 shows expected linearity error due to this increase.
Comparison made with the standard circuit Figure 5 and Figure 6, show that ZID circuits can yield 10 or even 100-fold improvement in linearity change over life resulting to mechanical wear.
Example 2: Exhaust gas recovery systems.
In modern engines, the reductions of pollution gasses are now controlled emissions.
One successful control method is the re-circulation of the exhaust gas on starting the engine to re burn the excess fuel until the correct operating temperature occurs. Such is a harsh environment can result significant mechanical and electrical output degradation. The critical input parameters are the closure of the re-circulation valve and the full open point of the re-circulation valve. A potentiometer device supplies position feedback. Changes in the two ends, particularly the closed position, will reduce the system efficiency and may cause failure. The cited circuit removes one of the electrical wear failures leaving only mechanical errors that can be now be over positioned by using a "Live" closed point.
This application is equally valid for I. Linear Motion Composition Slide Controls 2. Linear Exhaust Gas Recovery Sensors 3. Electronic Pedal Sensors 4. Electronic Accelerator Pedal Assemblies 5. Fuel Level Sensors 6. Rotary Position Sensors 7. Linear and Rotary Encoders 8. Any linear, non-linear, contact and non-contact sensor device
Claims (4)
- Claims 1. The invention, development and application of an impedancesensor circuit that eliminates output voltage change at the end-points as the result of physical mechanical wear at ambient and or extreme temperatures and humidity. See Figure 1.
- 2. The invention, development and application of the same impedance sensor circuit that minimises error voltage output between end points (linearity error) as a result of physical mechanical cycling, and or dithering (over life) at ambient and or extreme temperatures and humidity based on the appropriate selection of impedance in the circuit.
- 3. The principle beneficiaries of such invention, development and application are automotive sensors. However this invention, development and application applies equally to other manufacturing, scientific, commercial, medical, and industrial and entertainment industries requiring such change critical sensors.
- 4. The invention, development and application of the impedance circuit described in figure 1, is equally valid with contact and non-contact sensors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0701132A GB2446416A (en) | 2007-01-20 | 2007-01-20 | Zero idle drift sensor voltage measurement potentiometer circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0701132A GB2446416A (en) | 2007-01-20 | 2007-01-20 | Zero idle drift sensor voltage measurement potentiometer circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0701132D0 GB0701132D0 (en) | 2007-02-28 |
| GB2446416A true GB2446416A (en) | 2008-08-13 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0701132A Withdrawn GB2446416A (en) | 2007-01-20 | 2007-01-20 | Zero idle drift sensor voltage measurement potentiometer circuit |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2446416A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109490801A (en) * | 2017-09-12 | 2019-03-19 | 西门子(深圳)磁共振有限公司 | The detection method and device of the transmitting antenna level sensor of magnetic resonance imaging system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1127136A (en) * | 1964-12-18 | 1968-09-11 | David Hafler | Tone control |
| GB1192764A (en) * | 1967-07-03 | 1970-05-20 | British Petroleum Co | Method of Logging Boreholes |
-
2007
- 2007-01-20 GB GB0701132A patent/GB2446416A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1127136A (en) * | 1964-12-18 | 1968-09-11 | David Hafler | Tone control |
| GB1192764A (en) * | 1967-07-03 | 1970-05-20 | British Petroleum Co | Method of Logging Boreholes |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109490801A (en) * | 2017-09-12 | 2019-03-19 | 西门子(深圳)磁共振有限公司 | The detection method and device of the transmitting antenna level sensor of magnetic resonance imaging system |
| CN109490801B (en) * | 2017-09-12 | 2021-04-27 | 西门子(深圳)磁共振有限公司 | Method and apparatus for detecting transmitting antenna level sensor of magnetic resonance imaging system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0701132D0 (en) | 2007-02-28 |
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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) |