GB2389659A - A position measuring system - Google Patents
A position measuring system Download PDFInfo
- Publication number
- GB2389659A GB2389659A GB0213440A GB0213440A GB2389659A GB 2389659 A GB2389659 A GB 2389659A GB 0213440 A GB0213440 A GB 0213440A GB 0213440 A GB0213440 A GB 0213440A GB 2389659 A GB2389659 A GB 2389659A
- Authority
- GB
- United Kingdom
- Prior art keywords
- measuring system
- position measuring
- sensors
- piston
- cylinder
- 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- Withdrawn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
Classifications
-
- 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
- G01D5/142—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 using Hall-effect devices
- G01D5/145—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 using Hall-effect devices influenced by the relative movement between the Hall device and magnetic fields
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/20—Other details, e.g. assembly with regulating devices
- F15B15/28—Means for indicating the position, e.g. end of stroke
- F15B15/2815—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT
- F15B15/2861—Position sensing, i.e. means for continuous measurement of position, e.g. LVDT using magnetic means
-
- 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
- G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
- G01D11/24—Housings ; Casings for instruments
- G01D11/245—Housings for sensors
-
- 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
- G01D11/00—Component parts of measuring arrangements not specially adapted for a specific variable
- G01D11/30—Supports specially adapted for an instrument; Supports specially adapted for a set of instruments
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
- Actuator (AREA)
Abstract
The invention provides a system and method of determining the position of a first member linearly movable relative to a second member. The system includes several giant magnetoresistive (GMR) sensors associated with one member and means to receive signals from the sensors attached to the other member. One member may be a cylinder and the other a piston.
Description
r 1 2389659
IMPROVEMENTS IN OR RELATING TO POSITION CONTROL
This invention concerns improvements in or relating to position control.
More especially, the invention is concerned with determining the position 5 of a first member linearly movable relative to a second member, for example a piston slidable in a cylinder, and has application to a fluid power linear drive.
A common type of fluid power linear drive is a pneumatic piston/cylinder 10 unit in which reciprocating movement of the piston in the cylinder is employed to carry out a desired operation via a force transmitting member connected to the piston.
Currently a number of position measurement systems (position feedback 15 cylinders) are available for determining the position of a piston in a cylinder. The majority of these use either an LVDT (Linear variable differential transformer), linear potentiometer or magnetostrictive type position measurement device fitted concentrically inside the piston rod.
This requires the piston rod to be hollow and has many disadvantages for 20 both manufacture and use Firstly, the available piston area is reduced, reducing the available force for the cylinder. Secondly, the strength of the piston rod is severely reduced. Thirdly, manufacturing a hollow piston rod adds time and cost 25 to the manufacturing process - typically, due to logistical reasons, hollow piston rods will be gun drilled and not made from hollow stock. Fourthly the current methods increase the logistical complexity of the manufacturing process.
More especially, where such devices as described above are used, the position-sensing element is matched in length to the piston stroke of the device. As a result, the devices are frequently manufactured to the customers specified stroke length and this has obvious implications for the 5 logistics of matching the correct sized sensor to each individual stroke length. The combined effect of these is that to exert a force similar to a standard cylinder, then a position feedback cylinder must be sized bigger. Added 10 to this, the cost is significantly increased by the logistic complexity of the manufacturing process and increased lead times for getting the product to the customer.
Position feedback cylinders may be rodded in which the force 15 transmission member is a rod attached to the end of the piston or rodless in which the force transmission member is a carriage connected to the piston and slidable along the cylinder.
A further issue is that these measurement systems are difficult to integrate 20 into a rodless cylinder. For these devices and also for many rodded cylinder applications a "piggy back" approach is taken whereby the positioner is strapped onto the outside of the cylinder and the moveable portion is mechanically coupled onto the carriage (rodless) or end of the piston. This is generally a messy solution and leaves a sensitive 25 measuring device open to the atmosphere.
The present invention has been made from a consideration of the foregoing problems and disadvantages of the known position measurement systems.
Thus, according to one aspect of the present invention, there is provided a position measurement system for determining the position of a first member linearly movable relative to a second member, the system including magnetic means associated with the first member, a plurality of 5 giant magnetoresistive sensors associated with the second member and spaced apart in the direction of movement of the first member, and control means arranged to receive signals from the sensors in response to movement of the magnetic means past the sensors whereby the position of the first member relative to the second member can be determined By this invention, as the magnetic means moves past the array of giant magnetoresistive sensors (hereinafter GMR sensors), they each in turn output a signal that is input to the control means from which the position of the first part can be determined in real time by appropriate means.
For example, the control means may comprise electronic circuitry such as a microprocessor that interprets the input signals at high speed into an analogue output signal proportional to position in real time.
20 Typically, the system is calibrated on initial set-up to anew for any variance in the GMR sensors and the signals input to the control means from the GMR sensors may be amplified.
Preferably, the GMR sensors are uniformly spaced apart in the direction 25 of movement of the magnetic means and the magnetic means passes each GMR sensor at a uniform distance. In this way, a uniform response is obtained to movement of the magnetic means past each GMR sensor.
As each GMR sensor has an optimum range in which it operates, it is 30 desirable to operate in the optimum range to get the maximum benefit
from each GMR sensor. It is also desirable that the separation of the GMR sensors and the distance of the GMR sensors from the magnetic means remain constant throughout use to prevent incorrect outputs due to movement of the GMR sensors from their set or calibration positions.
Preferably, the system is shielded from outside magnetic influence. For example, shielding may be provided by a material with a suitable! permeability such as MuMetal (Registered Trade Mark).
10 Advantageously, the GMR sensors are provided on a circuit board for securing to the second member. In this way, the relative position of the i GMR sensors is fixed. As a result, installation is simplified.
In one arrangement, the circuit board extends over the range of relative 15 movement of the first and second members and includes all the GMR sensors. The circuit board preferably also includes the control circuitry (microprocessor) for input of signals from the GMR sensors. With this arrangement, the position measurement system is designed for a given application. In another arrangement, the GMR sensors are arranged in groups on circuit boards of pre-determined size to provide modules that can be connected together to provide an array of sensors for any desired range of relative movement of the first and second members.
The control circuitry (microprocessor) may be provided on one of the circuit boards (a master board) but more preferably, the control circuitry (microprocessor) is provided on a separate board to which a board having the GMR sensors is connected. With this arrangement, the position 30 measurement system can be adapted for different applications.
The magnetic means may comprise at least one permanent magnet such as a rare earth magnet on the first member. In this way, flying leads to the first member are avoided. As a result, installation and reliability is 5 enhanced.
In a preferred embodiment, the first member is a piston and the second member is a cylinder in which the piston is slidable with the position measurement system providing an indication of the position of the piston 10 in the cylinder.
The piston may be displaced by connecting one side of the piston to a source of pressure fluid. The fluid pressure may be a gas, for example air, or a liquid, for example oil. The piston may be reciprocated within 15 the cylinder by alternately connecting the source of pressure fluid to opposite sides of the piston.
The piston may be connected to a force transmitting member whereby movement of the piston is used to provide an output for any desired 20 purpose, for example, an actuator for a linear drive. The force transmitting member may be a piston rod connected to one end of the piston. Alternatively, the force transmitting member may be a carriage slidably mounted on the outside of the cylinder.
25 The piston may be reciprocated by alternately connecting the source of pressure fluid to opposite sides of the piston. The other side of the piston may be connected to vacuum or to a source of lower pressure fluid. In this way a pressure differential is created across the piston to displace the piston and the piston is reciprocated by reversing the pressure 30 differential.
According to another aspect of the invention, there is provided a method of determining the position of a first member linearly movable relative to a second member, the method comprising providing the first member with 5 magnetic means and the second member with a plurality of giant magnetoresistive sensors spaced apart in the direction of movement of the first member, and using signals generated by the sensors in response to movement of the magnetic means past the sensors to determine the position of the first member relative to the second member.
The first member may be a piston and the second member a cylinder in which the piston is slidable whereby the position of the piston can be accurately determined.
15 According to a further aspect of the invention, there is provided a cylinder, a piston movable lengthwise of the cylinder and a position measurement system for determining the position of the piston relative to the cylinder, the system including magnetic means associated with the piston, a plurality of giant magnetoresistive sensors spaced apart 20 lengthwise of the cylinder, each sensor being operable in response to movement of the magnetic means past the sensor to input a signal to control means for determining the position of the piston relative to the cylinder. 25 The piston may be connected to a force transmitting member for an actuator in the form of a linear drive or any other suitable purpose. The force transmitting member may be a rod attached to the piston and projecting from one end of the cylinder. Alternatively, the force transmitting member may be a carriage slidably mounted on the outside of 30 the cylinder.
The invention will now be described in more detail by way of example only with reference to the accompanying drawings wherein: 5 Figure l illustrates the lay-out of a position measurement system according to a first embodiment of the invention; Figure 2 illustrates the lay-out of a base unit of a modular position measurement system according to a second embodiment of the IO invention; Figure 3 illustrates the lay-out of a plug in sensor module for use with the base unit of the position measurement system shown in Figure 2; Figure 4 is a perspective view, partly exploded, showing application of the position measurement system of the invention to a linear actuator; and 20 Figure 5 is a section through the actuator of Figure 4.
Referring first to Figure 1 of the drawings, there is depicted schematically the lay-out of a first embodiment of a position measurement system. The system includes a plurality of GMR sensors 1-4 and a signal amplifier 5-8 for each sensor 1-4. In this embodiment, four sensors 1-4 are employed uniformly spaced apart in a longitudinal direction of movement of a signal magnet 9 indicated by the arrows Xl, X2.
The sensors 1-4 are connected in parallel between a power track 10 and a ground track It and the amplifiers 5-8 input signals to a microprocessor 12 via separate tracks 13-16.
5 The microprocessor 12 includes an application program to interpret the input signals from the sensors 1-4 into a proportional analogue signal via output track 17 representative of the real time position of the signal magnet 9 relative to the sensors 1-4.
10 Typically, the sensors 1-4, amplifiers 5-8, power track 10, ground track 11, microprocessor 12, input tracks 13-16 and output track 17 are assembled onto a circuit board. In this way, the spacing of the sensors 1 4 is fixed.
15 In use, the circuit board with sensors 1-4 thereon is mounted on one of two relatively movable members (not shown) and the signal magnet 9 is mounted on the other member. Generally, the circuit board will be on a stationary member and the signal magnet on a movable member.
20 In this way, as the magnet 9 passes each sensor 1-4, the sensor 1-4 generates a signal that is amplified and input to the microprocessor 12 from which the real time position of the moving member relative to the stationary member can be determined.
25 The system also includes a magnetic shield (not shown) that prevents any signals being generated by the sensors 1-4 as a result of any external magnetic source from directions other than the signal magnet 9.
Referring now to Figures 2 and 3, a second embodiment of the invention is shown that is a modular form of the first embodiment and capable of handling an array of up to 256 sensors.
5 This embodiment consists of a base unit 100 (Figure 2) and a plug in sensor module 101 (Figure 3).
The base unit 100 comprises a power input 102 and ground 103, an 8 bit demultiplexer 104, a microprocessor 105, an analogue output connection 10 106, a communications output 107, a signal input 108 and a connection socket 109 for the plug in sensor module all mounted on a circuit board.
The plug in sensor module 101 consists of an 8 bit decoder FIN, a plurality (in this case 4 are shown) of GMR sensors 111 and an associated 15 signal amplifier 112 for each sensor 111. The module 101 further includes a plug 113 at one end and a socket 114 at the other end, a power track 115, earth track 116, a communications track 117, an analogue signal track 118 and a means of identifying each board 119. The plug 113 enables the module 101 to be connected to the base unit 100 and the 20 socket 114 allows additional sensor modules 101 to be connected to increase the number of GMR sensors 111.
It will be appreciated that the above description of the electronic circuitry
is one example of a number of ways of achieving the same end result of a 25 modular GMR based position sensor capable of being adapted to different sizes. In use, the sensor module 101 is plugged into the base unit 100 and attached to one of two relatively movable members (not shown) , usually a 30 stationary member. A signal magnet (not shown) on the other, moving
al member is arranged to pass the GMR sensors 111 to generate signals that are input to the microprocessor 105 via the decoder 110 from which the real time position of the moving member can be determined.
5 Referring now to Figures 4 and 5, there is depicted application of the position measurement systems above described to an actuator 200 for a linear drive.
The actuator 200 consists of a fluid powered cylinder 201 having a piston 10 202 slidably mounted in cylinder body 203 and a piston rod 204 connected to the piston 202 and projecting from one end of the cylinder 201. The piston 202 can be reciprocated in the cylinder body 203 by 15 alternately connecting opposite sides of the piston 202 to a source of pressure fluid and vacuum via openings 205 (one only shown) in end caps 206, 207 at each end of the cylinder 201.
The pressure fluid may be a gas, for example air, in the case of a 20 pneumatic cylinder and a liquid, for example oil, in the case of a hydraulic cylinder.
The piston 202 is provided with a permanent magnet 203, for example a rare earth magnet such as neodymium-iron-boron (NdFeB) in the form of 25 an annular ring received in an annular groove in the outer surface of the piston 202.
A circuit board 209 on which a plurality of GMR sensors 210 (one only shown) are mounted together with the associated circuitry as described 30 previously is mounted externally along one side of the cylinder 201. The
J sensors 201 are uniformly spaced apart along the length of the cylinder 201. The board 209 is covered by a magnetic shield 211, for example a plate 5 of MuMetal (Registered Trade Mark) to protect the sensors 210 from the influence of any external magnetic fields.
In use, as the piston 202 moves in the cylinder 201, the magnet 208 passes the GMR sensors 210 generating signals that are fed into the 10 microprocessor (not shown) to generate an output signal representative of the real time position of the piston 202. By providing the magnet 208 in the form of an annular ring, the operation of the system is independent of the angular position of the piston 202 in the cylinder 201.
15 It will be appreciated that this system could be built into the cylinder 201 at point of manufacture or retrofitted as a separate part and that either a single sensing element (as in Figure 1) or a modular sensing element (as in Figures 2 and 3) could be used.
20 It will be understood that the invention is not limited to the embodiments above-described. For example, any number of GMR sensors may be employed as appropriate for a given application. One or more magnets may be used in conjunction with GMR sensors to generate the output signal for calculating the position of the movable member. Where more 25 than one magnet is provided these may be spaced apart axially and/or circumferentia11y and may interact with the same or different arrays of GMR sensors.
Other modifications that can be made will be apparent to those skilled in 30 the art and are deemed within the scope of the invention. Furthermore,
the invention includes any novel feature or combination of features described herein and the scope of the invention is to be construed accordingly. 5 It will also be appreciated that the system can be applied to a rodded cylinder as described in which the force transmitting member is a rod attached to the piston, and a rodless cylinder in which the force transmitting member is a carriage slidably mounted on an outer face of the cylinder and connected to the piston through a seal in the outer face.
Claims (21)
1. A position measuring system for determining the position of a first member linearly movable relative to a second member, the system including magnetic means associated with the first member, a plurality of giant magnetoresistive sensors (GMR) associated with the second member and spaced apart in the direction of movement of the first member, and control means arranged to receive signals from the sensors in response to movement of the magnetic means past the sensors whereby the position of the first member relative to the second member can be detennined.
2. A position measuring system according to claim 1, wherein the control means comprises electronic circuitry including a microprocessor.
3. A position measuring system according to claims I or 2, wherein the signal input to the control means from the GMR sensors is amplified.
4. A position measuring system according to any preceding claim, wherein the GMR sensors operate within their optimum range.
5. A position measuring system according to any preceding claim, wherein the GMR sensors are uniformly spaced apart in the direction of movement of the magnetic means and the magnetic means passes each GMR sensor at a uniform distance.
6. A position measuring system according to any preceding claim, wherein the separation of the GMR sensors and the distance of the GMR sensors from the magnetic means remains constant throughout use.
7. A position measuring system according to any preceding claim, wherein the GMR sensors are provided on a circuit board for securing to the second member.
(
8. A position measuring system according to claim 7, wherein the circuit board includes the control means including a microprocessor.
/
9. A position measuring system according to claims 7 or 8, wherein the circuit board extends over the range of relative movement of the first and second members and includes all the GMR sensors.
10. A position measuring system according to claim 7, wherein the GMR sensors are arranged in groups on circuit boards of pre-determined size connected to provide an array of sensors.
11. A position measuring system according to claims 10, wherein the control means comprising control circuitry is provided on a separate board with the circuits boards comprising the GMR sensors connected thereto.
12. A position measuring system according to any preceding claim, wherein the magnetic means comprises at least one permanent magnet on the first member.
13. A position measuring system according to claim 12, wherein the permanent magnet is a rare earth magnet.
14. A position measuring system according to any preceding claim, wherein the first member is a piston and the second member is a cylinder with the piston slidable therein.
15. A position measuring system according to any preceding claim, wherein the system is shielded from outside magnetic influences.
16. A method of determining the position of a first member linearly movable relative to a second member, the method comprising providing the first member with magnetic means and the second member with a plurality of GMR sensors spaced apart in the direction of movement of the first member, and using signals generated by the sensors in response to movement of the first member relative to the second member.
(
17. A method according to claim 16 wherein the first member is a piston and the ( second member is a cylinder in which the piston is slidable.
18. A device comprising a cylinder, a piston movable lengthwise of the cylinder and a position measuring system for determining the position of the piston relative to the cylinder, the system including magnetic means associated with the piston, a plurality of giant magnetoresisitive sensors spaced apart lengthwise of the cylinder, each sensor being operable in response to movement of the magnetic means past the sensor to input a signal to control means for determining the position of the piston relative to the cylinder.
19. A position measuring system substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.
20. A method of determining the position of a first member linearly movable relative to a second member substantially as hereinbefore described with reference to Figures 1 to 5 of the accompanying drawings.
21. A device substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0213440A GB2389659A (en) | 2002-06-12 | 2002-06-12 | A position measuring system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0213440A GB2389659A (en) | 2002-06-12 | 2002-06-12 | A position measuring system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0213440D0 GB0213440D0 (en) | 2002-07-24 |
| GB2389659A true GB2389659A (en) | 2003-12-17 |
Family
ID=9938408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0213440A Withdrawn GB2389659A (en) | 2002-06-12 | 2002-06-12 | A position measuring system |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2389659A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004090344A1 (en) * | 2003-04-07 | 2004-10-21 | Parker Hannifin Ab | Piston-cylinder device with position sensing means |
| WO2007064271A1 (en) * | 2005-12-02 | 2007-06-07 | Volvo Lastvagnar Ab | Magnetic detector arrangement |
| WO2012011918A1 (en) * | 2010-07-23 | 2012-01-26 | Halliburton Energy Services, Inc. | Method and apparatus for measuring linear displacment |
| EP3326269A4 (en) * | 2015-06-01 | 2018-10-10 | Prime Datum Development Company, LLC | Line replaceable unit (lru) sensor systems for motors and other machines |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2199145A (en) * | 1986-11-13 | 1988-06-29 | Ckd Corp | Piston position detector for fluid pressure cylinder |
| GB2205406A (en) * | 1987-06-04 | 1988-12-07 | Spectrol Reliance Ltd | Encoder apparatus |
| DE3833399A1 (en) * | 1988-10-01 | 1990-04-12 | Bosch Gmbh Robert | Method for measuring the position of a moving part arranged in a pump housing |
| DE4429857A1 (en) * | 1994-08-23 | 1996-02-29 | Balluff Gebhard Feinmech | Magnet position detector for magnet moving along a path |
| EP0707195A1 (en) * | 1994-10-14 | 1996-04-17 | Sumitomo Electric Industries, Ltd. | Magnetically controlled detection of the movement of a mobile part with respect to a fixed part |
| US5936400A (en) * | 1996-12-23 | 1999-08-10 | Federal Products Co. | Magnetoresistive displacement sensor and variable resistor using a moving domain wall |
| DE10022869A1 (en) * | 2000-05-10 | 2001-11-15 | Secatec Electronic Gmbh | Short sensor element, has electronics resistance to electromagnetic compatibility problems, short circuits, polarity inversion with giant magnetoresistive sensor detecting piston position |
| DE10046500A1 (en) * | 2000-09-20 | 2002-03-28 | Secatec Electronic Gmbh | Magneto-resistive sensor surface based on a thick layer paste deposited on a ceramic substrate in the form of a measurement strip that detects the movement of a permanent magnet attached to a pneumatic or hydraulic piston, etc. |
-
2002
- 2002-06-12 GB GB0213440A patent/GB2389659A/en not_active Withdrawn
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2199145A (en) * | 1986-11-13 | 1988-06-29 | Ckd Corp | Piston position detector for fluid pressure cylinder |
| GB2205406A (en) * | 1987-06-04 | 1988-12-07 | Spectrol Reliance Ltd | Encoder apparatus |
| DE3833399A1 (en) * | 1988-10-01 | 1990-04-12 | Bosch Gmbh Robert | Method for measuring the position of a moving part arranged in a pump housing |
| DE4429857A1 (en) * | 1994-08-23 | 1996-02-29 | Balluff Gebhard Feinmech | Magnet position detector for magnet moving along a path |
| EP0707195A1 (en) * | 1994-10-14 | 1996-04-17 | Sumitomo Electric Industries, Ltd. | Magnetically controlled detection of the movement of a mobile part with respect to a fixed part |
| US5936400A (en) * | 1996-12-23 | 1999-08-10 | Federal Products Co. | Magnetoresistive displacement sensor and variable resistor using a moving domain wall |
| DE10022869A1 (en) * | 2000-05-10 | 2001-11-15 | Secatec Electronic Gmbh | Short sensor element, has electronics resistance to electromagnetic compatibility problems, short circuits, polarity inversion with giant magnetoresistive sensor detecting piston position |
| DE10046500A1 (en) * | 2000-09-20 | 2002-03-28 | Secatec Electronic Gmbh | Magneto-resistive sensor surface based on a thick layer paste deposited on a ceramic substrate in the form of a measurement strip that detects the movement of a permanent magnet attached to a pneumatic or hydraulic piston, etc. |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004090344A1 (en) * | 2003-04-07 | 2004-10-21 | Parker Hannifin Ab | Piston-cylinder device with position sensing means |
| US7437988B2 (en) | 2003-04-07 | 2008-10-21 | Parker Hannifin Ab | Piston-cylinder device with position sensing means |
| WO2007064271A1 (en) * | 2005-12-02 | 2007-06-07 | Volvo Lastvagnar Ab | Magnetic detector arrangement |
| EP1969318A1 (en) * | 2005-12-02 | 2008-09-17 | Volvo Lastvagnar Ab | Magnetic detector arrangement |
| EP1969318A4 (en) * | 2005-12-02 | 2010-10-06 | Volvo Lastvagnar Ab | Magnetic detector arrangement |
| WO2012011918A1 (en) * | 2010-07-23 | 2012-01-26 | Halliburton Energy Services, Inc. | Method and apparatus for measuring linear displacment |
| US9671211B2 (en) | 2010-07-23 | 2017-06-06 | Halliburton Energy Service, Inc. | Method and apparatus for measuring linear displacement |
| EP3326269A4 (en) * | 2015-06-01 | 2018-10-10 | Prime Datum Development Company, LLC | Line replaceable unit (lru) sensor systems for motors and other machines |
| US10804770B2 (en) | 2015-06-01 | 2020-10-13 | Prime Datum Development Company, Llc | Line replaceable unit (LRU) sensor systems for motors and other machines |
| US11990798B2 (en) | 2015-06-01 | 2024-05-21 | Prime Datum Development Company, Llc | Line replaceable unit (LRU) sensor systems for motors and other machines |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0213440D0 (en) | 2002-07-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| COOA | Change in applicant's name or ownership of the application |
Owner name: PANKHURST DESIGN & DEVELOPMENTS LIMITED Free format text: FORMER APPLICANT(S): IMI VISION LIMITED |
|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |