WO2006056650A1 - Capteur d'efforts robuste, systeme de commutation, installation de terrain de jeu et procede d'installation associe - Google Patents

Capteur d'efforts robuste, systeme de commutation, installation de terrain de jeu et procede d'installation associe Download PDF

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Publication number
WO2006056650A1
WO2006056650A1 PCT/FI2005/000510 FI2005000510W WO2006056650A1 WO 2006056650 A1 WO2006056650 A1 WO 2006056650A1 FI 2005000510 W FI2005000510 W FI 2005000510W WO 2006056650 A1 WO2006056650 A1 WO 2006056650A1
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WO
WIPO (PCT)
Prior art keywords
wire
wires
force sensor
core
excitation
Prior art date
Application number
PCT/FI2005/000510
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English (en)
Inventor
Matti Rahkala
Original Assignee
Lappset Group Oy
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 Lappset Group Oy filed Critical Lappset Group Oy
Publication of WO2006056650A1 publication Critical patent/WO2006056650A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B2220/00—Measuring of physical parameters relating to sporting activity
    • A63B2220/50—Force related parameters
    • A63B2220/51—Force
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B5/00—Apparatus for jumping

Definitions

  • the invention concerns generally the technology of sensing force, i.e. giving an (electronic) indication about a detected occurrence of a force affecting a well- defined target. Especially the invention concerns force sensors that are used in playground equipment.
  • a playground is understood to be a place equipped for activities that aim at cognitive, motoric and social development and education through an attractive and amusing way.
  • An amusement park is not a playground, because it only aims at producing experiences of amusement and excitement without said educational function.
  • An amusement park is always built for occasional visits, manned with personnel, and subject to charge.
  • a playground is nearly always unmanned and freely accessible for regular visits by players.
  • a playground may be defined to be a place equipped with playthings that obey the appropriate standards, which in Europe means a standard known as EN 1176 for equipment and another known as EN 1177 for materials.
  • playground equipment might contain sensors adapted to generate inputs to a sig- nal processing entity that collects and processes information about what the play ⁇ ers are doing. This sets very tight requirements to the components used, because a playground constitutes a relatively hostile environment. All components must stand humidity, sand, dirt and dust, temperatures between at least -40 and +50 centigrade, harsh treatment and even pure vandalism. Additionally playground equipment are big, which usually means a relatively large amount of on-site work during installation.
  • One basic building block for an electronically enhanced playground is a force sen ⁇ sor. It may be used for a variety of applications having the common requirement that one wants to know, when a player exerts a force directly or indirectly against a certain target. Sometimes even the magnitude of the force should be detected.
  • playground equipment needing a number of force sensors we will consider the arrangement of adjacent flat squares on the ground illustrated sche- matically in fig. 1, to be used for games such as hopscotch.
  • a force sensor 101 within each square would be typically needed for detecting, when the player stands on a square, or touches or kicks one with his foot.
  • each force sensor 101 there comes the required number of wires. Basically it would be possible to implement each force sensor 101 as an independent on/off switch, e.g. so that a common source voltage line circulates through all squares and an individual return wire comes from each switch to an input/output unit of a signal processing unit. This would mean that an arrangement of N squares would need N+1 wires, where N is a positive integer. With an increasing number of squares this easily becomes a limiting factor, con- sidering e.g. the high cost of installation work outdoors and the accumulating reli ⁇ ability problems caused by numerous galvanic connections.
  • a known solution reducing the number of wires is to divide the "keypad" into a ma ⁇ trix of rows and columns, and to use one wire for each row and one for each col- umn like in fig. 1.
  • Selectively coupling excitation signals to either the row or the column wires and detecting their occurrence in the other group of wires enables deducing, at which crossing a switch was closed.
  • Such a switch matrix approach involves the inherent drawback of creating ghost couplings when more than two keys are pressed simultaneously. If, in the arrangement of fig. 1, one player has his feet on squares 111 and 112 and another stands on square 113, the circulation of currents may easily result in the detection electronics assuming that there is a coupling in square 114 also.
  • a single closed switch with very low impedance in the closed state may "leak" the excitation signal so effectively to the corresponding detection wire that simultaneously closing another switch further down the same excitation wire will only cause a negligible additional effect, causing the latter switch-closing to go undetected.
  • An objective of the present invention is to provide a sensing principle, a force sen ⁇ sor structure and a switching arrangement that enable building robust and reliable force sensors capable of surviving playground conditions. Additionally it is an ob- jective of the invention that the sensing principle, force sensor structure and switching arrangement make it possible to reliably detect multiple simultaneous forces. A yet another objective of the invention is that the sensing principle, sonce sensor structure and switching arrangement enable quick and easy installation in outdoor conditions. A yet another objective of the invention is to provide an instal ⁇ lation method of a playground appliance that includes a force sensor of the afore ⁇ mentioned kind.
  • the objectives of the invention can be achieved by using an inductive switch struc- ture, in which an exerted force causes a change in the mechanical characteristics of a ferromagnetic core, which carries an electromagnetic field induced by an exci ⁇ tation current.
  • a force sensor according to the invention is characterised by the features recited in the characterising part of the independent claim directed to a force sensor.
  • a switching arrangement according to the invention is characterised by the fea ⁇ tures recited in the characterising part of the independent claim directed to a switching arrangement.
  • a playground appliance according to the invention is characterised by the features recited in the characterising part of the independent claim directed to a playground appliance.
  • a method according to the invention for installing a playground appliance is char ⁇ acterised by the features recited in the characterising part of the independent claim directed to such a method.
  • An alternating excitation current coupled to an excitation wire causes an electro ⁇ magnetic field to be induced around the excitation wire. If a section of the excita ⁇ tion wire is placed close to a ferromagnetic core, said core acts a local concentra- tor of the electromagnetic field.
  • the density of magnetic flux in the core depends on a number of factors, including the mechanical characteristics of the core and its location in relation to the excitation wire. If the core constitutes an incomplete loop having an air gap, and the excitation wire goes through said loop, the density of magnetic flux in the core depends strongly on the width of the air gap. Narrowing the air gap strengthens the flux, while widening the gap weakens the flux.
  • the strength of the electromagnetic coupling between the excitation and detection wires depends also on the width of the air gap.
  • the amount of electric energy coupled from the excitation wire to the detection wire is the larger the narrower is the air gap in the core.
  • Two parts of the core may be supported, with the help of elastic support such as spring(s), rubber cushion(s) or the like, in a position where the air gap has a cer ⁇ tain first width.
  • elastic support such as spring(s), rubber cushion(s) or the like.
  • Exerting a force on the switch structure causes the width of the air gap to change, which causes a corresponding change in the amount of electric energy coupled from the excitation wire to the detection wire.
  • this change can be detected and associated with a force acting on a force sensor including the switch structure.
  • Fig. 1 illustrates a prior art switching arrangement
  • fig. 2 illustrates an operational principle used in an embodiment of the inven ⁇ tion
  • fig. 3 illustrates an operational principle used in another embodiment of the invention
  • fig. 4 illustrates a switch structure from above
  • fig. 5 illustrates a switch structure in cross-section
  • fig. 6a illustrates an alternative core configuration
  • fig. 6b illustrates another alternative core configuration
  • fig. 7a illustrates a wiring scheme
  • fig. 7b illustrates placing a switch under an elastic square
  • fig. 8 illustrates a detection interface circuit
  • fig. 9 illustrates a circuit arrangement for operating a switch matrix.
  • Fig. 2 illustrates a switch structure where the varying strength of inductive coupling is utilised for controlling the amount of electric energy transferred from an excita ⁇ tion wire to a detection wire.
  • the excitation wire 201 is a twisted pair loop, as is the detection wire 202.
  • An alternating excitation current 203 is fed into the excitation wire 201.
  • the switch is considered to be closed when a corresponding detection current 204 of sufficient magnitude occurs in the detection wire 202. This is achieved so that at one section of the twisted pair constituting the excitation wire 201 the intertwined configuration is opened enough to slide one branch of a ferro- magnetic U core 205 in between the wires.
  • the intertwined configuration of the twisted pair constituting the detection wire 202 is opened at a certain section enough to slide another branch of the ferromagnetic U core 205 in between the wires.
  • a ferromagnetic I section 206 is located next to the open ends of said branches of the ferromagnetic U core 205, but separated therefrom by an air gap 207.
  • the supporting arrangement of the ferromagnetic I section 206 comprises a degree of elasticity, which is schematically shown in fig. 2 as springs 208.
  • the alternating excitation current 203 induces an alternating magnetic field around the excitation wire 201.
  • the intertwined configuration of a twisted pair ensures that for most of the length thereof, magnetic fields of the forward and return direction wires cancel each other.
  • locally a relatively strong magnetic field is in ⁇ **d in the ferromagnetic U core 205.
  • the strength at which such a magnetic field is capable of transferring electric energy from the excitation wire 201 to the detection wire 202 depends on the width of the air gap 207.
  • the magnitude of alternating current observed in the detection wire 202, or some processed deriva- tive thereof, can be compared to a threshold, enabling on/off type detecting: an "on" signal is only given if the detection current 204 is larger than a certain limit.
  • the very same switch structure could be also used as an indicator of a pulling force rather than a pushing or pressing force 209 like in fig. 2.
  • the in- ductive coupling between the excitation and detection wires through the ferromag ⁇ netic core arrangement would be relatively strong in the rest position.
  • a pulling force would enlargen the air gap 207, which would be detected through a decreas ⁇ ing detection current 204 caused by a weakening inductive coupling.
  • Fig. 3 illustrates an alternative principle for a switch structure, in which a pressing force 309 is detected through a decreasing detection current 204 caused by a weakening inductive coupling.
  • a pulling force would be correspondinly detected through an increasing detection current 204 caused by the inductive coupling get ⁇ ting stronger.
  • the elastic support 308 now supports the ferromagnetic U core 205, and the moving effect of the pressing force 309 is brought to the ferromagnetic U core 205 through a strut 301.
  • Figs. 4 and 5 illustrate an exemplary physical implementation of a switch employ- ing the principle described previously in association with fig. 2.
  • the mechanical structure of the switch comprises two main units, which are here designated as the lower unit 400 and the upper unit 500.
  • Fig. 4 is a top view of a lower unit 400 with two twisted wire pairs installed, while fig. 5 is a cross-section view of a lower unit
  • the lower unit 400 is basically a cup-formed piece 401 of a material having good mechanical strength, such as aluminium or durable plastic.
  • the ma- terial of the cup-formed piece 401 should not exhibit substantial ferromagnetism.
  • the side walls of the cup-formed piece 401 comprise a number of openings for wiring. In this embodiment there are four openings 402, 403, 404 and 405 spaced at equal angular intervals, although some other number of openings and some other locations could also be used.
  • ferromagnetic U core 205 At the middle of the inner bottom of the cup-formed piece 401 there is a ferromagnetic U core 205, which is held in place with suitable fastening means, such as glue, screw(s), mechanical attachment clips or the like.
  • suitable fastening means such as glue, screw(s), mechanical attachment clips or the like.
  • a number of springs 208 are located around the ferromagnetic U core 205.
  • An ex ⁇ citation wire 201 comes in through one of the openings 402 as a twisted pair and exits through another opening 404. Close to the ferromagnetic U core 205 the in ⁇ tertwined configuration of the twisted pair has been opened enough to slide one branch of a ferromagnetic U core 205 in between the wires. The same applies to a detection wire 202, which comes in through opening 405 and exits through open ⁇ ing 403.
  • the upper unit 500 is basically just a cover plate 501 adapted to match the cup- like form of the lower unit 400 to constitute an essentially closed enclosure.
  • a ferromagnetic I section 206 is held in place with suitable fastening means, such as glue, screw(s), mechanical attach- ment clips or the like.
  • pegs 502 attached to the cover plate 501 , so that when the up ⁇ per and lower units are assembled together, the springs 208 glide over the pegs 502.
  • the pegs 502 serve both as supports for the springs 208, keeping them from bending sideways, and as movement limiters that keep the upper and lower units from being pushed together more than appropriate.
  • the limiting function is advan ⁇ tageous especially if the ferromagnetic pieces 205 and 206 are brittle: movement limiters keep them from hitting each other, which might otherwise cause mechani ⁇ cal damage.
  • the upper and lower units constitute a kind of a closed box, in which the lid (the cover plate 401) rests on the springs 208.
  • An air gap separates the ferromagnetic I section 206 from the branches of the ferromag ⁇ netic U core 205. If a pressing force presses the upper and lower units together, the longitudinal elastic contraction of the springs 208 allows the width of said air gap to decrease, until the pegs 502 hit the the lower unit 400 (in the embodiment of fig. 5, the bottom of the corresponding spring attachment hollows). When the pressing force disappears, the elasticity of the springs 208 push the upper unit 500 back to the rest position.
  • the variation range of the air gap should be selected so that it provides a wide dynamic range; in other words, the strength of the electromagnetic coupling between the excitation and de ⁇ tection wires should vary in a relatively wide range depending on whether a press- ing force acts on the switch or not.
  • the electromagnetic coupling should be "loose", so that only a few per cent of the energy of the excitation current will be transferred to the detection wire. The looseness of the coupling ensures that still enough energy will remain in the exci ⁇ tation wire for the needs of other, simultaneous couplings in switches further down the line.
  • the elastic support means and the movement limiters are structural de ⁇ tails that could be realised in practice with a number of widely different alternative ways.
  • the matching edges of the cup-formed piece 401 and the cover plate 501 could comprise matching lips or rebates so dimensioned that in the pressed configuration a lip in one part would touch a bench in the other part and thus act as a movement limiter.
  • the elastic support means could consist of an elastic ring seal between a lip in one part and a bench in the other.
  • the ferromagnetic core arrangement comprises a lower half toroid 611 and an upper half toroid 612, with the excitation wire 201 and the detection wire 202 having been slid onto dif ⁇ ferent halves (although they could be on the same half too).
  • Other possible combi- nations include but are not limited to an E+E pair, slotted potcore halves, slotted potcore with flat lid and half toroid with an I section.
  • fig. 6a could also be interpreted as representing an embodiment of the invention, in which the ferromagnetic material used for the core also has suitable mechanical properties to be used as the body material of the switching structure.
  • the lower part shown in fig. 6 could be the cross-section of a cup-formed body part otherwise resembling that shown in figs. 4 and 5 as 401 but having a protruding peg at its center.
  • the upper part shown in fig. 6 would then be the cross-section of a plate-like lid, which together with the cup-formed body part would constitute an enclosure, with the necessary elastic supports etc. placed therebetween (not shown in fig. 6a). This way one would avoid the need for a separate ferromagnetic core inside the mechanical overall structure of the switch.
  • the invention does not require the ferromagnetic core to consist of two pieces.
  • the ferromagnetic core could consist of a gapped toroid, resembling the embodiment of fig. 6b but with the halved toroid illustrated therein being continuous over one of the left-hand or right-hand side gaps shown in fig. 6b.
  • the material of such a gapped toroid core should be flexible enough both to allow a pressing force to narrow or widen the remaining gap enough to ob- tain the required dynamic range of electromagnetic coupling, and to stand such bending a very large number of times.
  • a typical requirement that applies to all switch constructions according to the invention is endurance over one million repe ⁇ titions.
  • the ferromagnetic core would not constitute a gapped loop but e.g. a linear shaft constructed in a way that allows changing the efficiency at which the ferromagnetic core transfers electromagnetic energy as a response to a move- ment.
  • the linear shaft could comprise two pieces with finger-like branches in the ends of said pieces facing each other, so that a compressing movement would slide the finger-like branches towards tighter interlocking.
  • Fig. 7a illustrates an exemplary way of wiring a 4 x 4 matrix of hopscotch squares that are equipped with switches 701 of the kind illustrated above in figs. 4 and 5.
  • the invention provides a system designer with a considerable degree of freedom in selecting a wiring strategy, mainly because adding switches to a wire does not increase the number of galvanic connections and because one closed switch only draws a very limited amount of energy from an excitation wire, meaning that even one excitation wire can support even a relatively large number of switches.
  • fig. 7a is mainly an example of the principle that the wiring does not need to conform strictly to the columns and rows, but for example a single excitation wire may serve a larger number of switches.
  • Each excitation wire and each detection wire is a twisted pair loop, which in fig.
  • 7a is illustrated by showing the two open ends of each wire at the lower part of the drawing and a closed loop at the oppo ⁇ site extremity; physically the closed loop may indeed be just a wire bend, so that the twisted pair is actually a single wire twisted around itself, or the closed loop may be a short circuit between two wires twisted around each other.
  • the principle of using a suitable number of excitation wires and a suitable number of detection wires can be easily extended to an arbitrary number of switches in arbitrary order.
  • Fig. 7b is a partial cross-section of an advantageous structural principle for con ⁇ structing one hopscotch square.
  • An elastic cushion 751 made e.g. of a material known by the trade name Softex constitutes the visible and touchable part.
  • a hol ⁇ low 752 below the elastic cushion 751 houses the switch 701 , so that stepping on the top surface of the elastic cushion 751 causes its central part to elastically bend downwards and to press the switch 701.
  • FIG. 8 illustrates an exemplary piece of detection circuitry 800.
  • One end of the twisted pair loop that serves as a detection wire 202 is connected to ground, while the other end is cou ⁇ pled through a DC separation capacitor 801 to the middle point of two Schottky di ⁇ odes 802 and 803 coupled in series.
  • the anode of the lower diode 802 is con- nected to ground. From the cathode of the upper diode 803 there are parallel con ⁇ nections to ground through a capacitor 804 and a resistor 805 respectively, as well as to the positive input terminal of a differential amplifier 806.
  • the negative input terminal of the differential amplifier 806 is coupled to a reference voltage Uref and the output line 807 of the differential amplifier 806 is coupled to a positive voltage Vcc through a pull-up resistor 808.
  • An oscillating current in the detection wire 202 causes a voltage to accumulate between the poles of the capacitor 804.
  • an output signal is given at the output line 807 of the differential amplifier 806.
  • the output line 807 gives a simple one-bit digital indication of whether a current has been detected or not.
  • a straightforward development towards detecting the magnitude of a pressing force would involve replacing the differential amplifier 806 with an A/D converter having its input range adapted to the range of input signals that are likely to occur at various pressing forces on a switch.
  • simple three-level detection could be implemented by using two differential amplifiers in parallel and giving each of them a different reference voltage.
  • Fig. 9 illustrates an exemplary circuit 900 adapted to be coupled to an array of switches, in order to provide the switches with excitation signals and to detect when switches are closed.
  • the functional core of the circuit 900 is a microproces ⁇ sor 901 , an input connection of which is coupled to a number of detection wires through interfacing circuits, which in fig. 9 are of circuits 800 of the type described above in association with fig. 8.
  • a signal source 902 is adapted to produce an exci ⁇ tation signal, which is preferably an AC voltage signal the frequency of which has been selected so that it propagates easily in the type of excitation and detection wires used and transfers energy efficiently through the ferromagnetic cores used in the switches.
  • the frequency of the signal produced by the signal source 902 is in the range of audio frequencies, i.e. a few thousands of kHz.
  • the output of the signal source 902 is coupled to a data input of a demultiplexer 903, an address input of which is coupled to an output of the microprocessor 901.
  • An N-bit address word given by the microprocessor 901 determines, which of the 2 N outputs of the demultiplexer 903 emits the signal from the signal source 902 to an excitation wire 201. Coupled in series with each excitation wire 201 there are a shunt resistor 904 and a DC decoupling capacitor 905.
  • the microprocessor 901 sequentially writes each valid address word in turn to the demultiplexer 903, which consequently couples the signal from the signal source 902 to each excitation wire in turn.
  • the frequency at which the microprocessor 901 changes the address word is such that a full cycle through all used address words is shorter than an expected minimum duration of a switch closing to be detected.
  • the microprocessor waits for detection sig- nals to come from the interface circuits 800.
  • microprocessors read data in a byte-oriented way (at least) 8 bits at a time, which means that up to (at least) 8 detection wire interface circuits can be read simultaneously. If a microprocessor reads less bits at a time than there are detection wires, it is possible to use a read-in multiplexer in a man ⁇ ner that is essentially a mirror image of that applied to the demultiplexer 903 on the excitation side. Making the microprocessor associate a detected combination of a current excitation address word and detected input signal(s) in is well known from the technique of keypads and does not need to be described here in detail.
  • an ordinary logic circuit such as a 74HC138 demultiplexer is more the enough to drive as many as eight excita ⁇ tion wires without any specific driver circuits therebetween.
  • An excitation voltage of 5 volts and an excitation current of 10 milliamperes has been found to produce de- tection voltages of several hundreds of millivolts in a detection capacitor like the one shown as 804 in the circuit 800, which is well sufficient for reliable detection.
  • the use of twisted wire pairs as excitation and detection wires helps to achieve a good signal to noise ratio, since twisted pairs pick up only a very limited amount of external electromagnetic noise. The use of twisted pairs also helps to keep any stray electromagnetic radiation emitted by the switch field at a negligible value.
  • circuit shown in fig. 9 can be built as a "black box" with no need of any soldering, wire skinning or galvanic contacts of any kind outside a main electronics unit. Operating power comes through one wire to the electronics unit, and excitation and detection wires come as twisted pairs. Separate wiring may be provided for interfacing with display and storage devices, if needed; in order to avoid wiring also wireless con- nections can be used.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)

Abstract

L'invention concerne un capteur d'efforts servant à détecter un effort dans une installation de terrain de jeu, et qui comprend un noyau ferromagnétique (205, 206, 601, 602, 611, 612) comportant un entrefer (207). Un support (208, 308) élastique, qui maintient une partie du noyau ferromagnétique, est sensible à une force (209, 309) exercée sur le capteur d'efforts et qui modifie une dimension de celui-ci. Un fil d'excitation (201, 711, 712) et un fil de détection (202, 721, 722, 723, 724, 725, 726, 727, 728) définissent ensemble une boucle autour d'une partie du noyau ferromagnétique. Une force (209, 309) produisant un changement dans l'entrefer (207) modifie le couplage électromagnétique entre le fil d'excitation et le fil de détection.
PCT/FI2005/000510 2004-11-25 2005-11-25 Capteur d'efforts robuste, systeme de commutation, installation de terrain de jeu et procede d'installation associe WO2006056650A1 (fr)

Applications Claiming Priority (2)

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FI20041516 2004-11-25
FI20041516A FI20041516A (fi) 2004-11-25 2004-11-25 Varmatoiminen voima-anturi, kytkentäjärjestely, leikkikenttäväline ja menetelmä sen asentamiseksi

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WO2006056650A1 true WO2006056650A1 (fr) 2006-06-01

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008134906A1 (fr) * 2007-05-04 2008-11-13 Carag Ag Balance
CN102500091A (zh) * 2011-11-03 2012-06-20 西安交通大学 一种多功能起跳板
EP2787336A4 (fr) * 2011-11-30 2015-09-02 Univ Zhejiang Dispositif de surveillance d'effort de type d'effet magnéto-élastique et magnétoélectrique

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5359902A (en) * 1993-07-15 1994-11-01 Bolt Beranek And Newman Inc. Load cell
US5814740A (en) * 1993-05-20 1998-09-29 Advanced Mechanical Technology, Inc. Multi-axis force platform
US20020092358A1 (en) * 2001-01-12 2002-07-18 Trw Inc. Magnetostrictive stress sensor
US20020160667A1 (en) * 2001-04-26 2002-10-31 Bbnt Solutions Llc Load measurement device
EP1279938A1 (fr) * 2001-07-24 2003-01-29 Starr Johnson Dispositif de detection de charge utilisant saturation magnétique
JP2003194639A (ja) * 2001-12-25 2003-07-09 Matsushita Electric Works Ltd 力センサ

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5814740A (en) * 1993-05-20 1998-09-29 Advanced Mechanical Technology, Inc. Multi-axis force platform
US5359902A (en) * 1993-07-15 1994-11-01 Bolt Beranek And Newman Inc. Load cell
US20020092358A1 (en) * 2001-01-12 2002-07-18 Trw Inc. Magnetostrictive stress sensor
US20020160667A1 (en) * 2001-04-26 2002-10-31 Bbnt Solutions Llc Load measurement device
EP1279938A1 (fr) * 2001-07-24 2003-01-29 Starr Johnson Dispositif de detection de charge utilisant saturation magnétique
JP2003194639A (ja) * 2001-12-25 2003-07-09 Matsushita Electric Works Ltd 力センサ

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008134906A1 (fr) * 2007-05-04 2008-11-13 Carag Ag Balance
CN102500091A (zh) * 2011-11-03 2012-06-20 西安交通大学 一种多功能起跳板
EP2787336A4 (fr) * 2011-11-30 2015-09-02 Univ Zhejiang Dispositif de surveillance d'effort de type d'effet magnéto-élastique et magnétoélectrique

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FI20041516A (fi) 2006-05-26
FI20041516A0 (fi) 2004-11-25

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