WO2004091399A1 - Method and independent device for the determination of the relative position of two objects moving on a plane or in space - Google Patents

Method and independent device for the determination of the relative position of two objects moving on a plane or in space Download PDF

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Publication number
WO2004091399A1
WO2004091399A1 PCT/FR2004/000806 FR2004000806W WO2004091399A1 WO 2004091399 A1 WO2004091399 A1 WO 2004091399A1 FR 2004000806 W FR2004000806 W FR 2004000806W WO 2004091399 A1 WO2004091399 A1 WO 2004091399A1
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Prior art keywords
characterized
length
objects
wire
transmitter
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PCT/FR2004/000806
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French (fr)
Inventor
Maurice Ouaknine
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Universite De La Mediterranee Etablissement Public D'enseignement Superieur Et De Recherche
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Priority to FR0304300A priority Critical patent/FR2853221B1/en
Priority to FR03/04300 priority
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Publication of WO2004091399A1 publication Critical patent/WO2004091399A1/en

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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/68Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6813Specially adapted to be attached to a specific body part
    • A61B5/6829Foot or ankle
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/103Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/1036Measuring load distribution, e.g. podologic studies
    • A61B5/1038Measuring plantar pressure during gait
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00Navigation; Navigational instruments not provided for in preceding groups
    • G01C21/20Instruments for performing navigational calculations
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C22/00Measuring distance traversed on the ground by vehicles, persons, animals, or other moving solid bodies, e.g. using odometers, using pedometers

Abstract

The invention relates to an independent device for the determination of the relative position of two objects or bodies moving on a plane or in space, for example of application in the kymographic analysis of gait, characterised in comprising at least two complementary devices (1, 3, 2, 4), for carrying out a measurement of the length of the straight line between two reference points (D, G), respectively attached to two objects when placed at a distance from each other and for the measurement of at least one angle for said straight line with relation to a plane from which at least one end of said straight line extends.

Description

Method and self-contained device for determining the relative position of two objects moving in a plane or in space.

The present invention relates to a method and self-contained device for determining the relative position of two objects or bodies moving in a plane or in space.

The method and the autonomous device according to the invention are more particularly useful in applications where it is desired to analyze the motion of a set of at least two objects in reciprocating motion relative to each other. However, to simplify the presentation of the prior art, reference is made primarily in the following discussion, to posturology applications or studies of walking. On the other hand, in sake of brevity, the method and the self-contained device of the invention are only described below with reference to their preferred application to kymographique gait analysis.

The kymographique gait analysis is based on kinematic measurement of one or several points of the body of a living being for locomotion. Its purpose is to determine the spatio-temporal gait parameters such as the speed, stride length, cadence, asymmetry not, support phases, swinging, etc., for example in order to take stock of the locomotor function of a subject.

To highlight the value of the process and standalone device according to the invention, it is well to remember the art in the field of travel. Among the known systems include: A - video kymographique analysis (Elite® systems Vicon® etc.). One or more cameras placed in the subject field evolution capture the reflective target images pasted on the body of the subject. An acquisition and processing software determines the coordinates of said target. This type of device has the advantage of letting free to move the topic. But has the following disadvantages: - Low frequency dependent acquisition of the number of frames per second

- Scope limited changes (a few meters)

- Complex processing software - delicate calibration procedure

- The target of the masking problem involves the use of multiple cameras.

- Very expensive ; etc.

Among the devices that are within image analysis are:

• US Patent 4631676 James W.Pugh of 23 December 1986 which describes a walking analysis method based on the principle described above. The reflective markers are placed on the major joints (ankles, knees, hips) of the subject.

• US Patent 6438255 Jon R.Lesniak of 20 August 2002 discloses a certainly interesting variant in that the targets are temperature points on the body of the subject obtained by irradiation on any body part to study. A thermal camera can track said points during their evolution. But the drawbacks are those inherent in the video kymographique analysis. o US Patent 4813436 Jan C.Au 21 March 1989 describes an analytical system of walking using one or more cameras to analyze the movement of reflective markers placed on joints. The supports of the feet on the floor as well as the distribution of forces are measured using piezo-sensitive surface sandals.

B - Treadmill with piezo-sensitive cells

The subject moves on a treadmill capable of providing through a matrix of piezo-sensitive cells the electronic fingerprint of each step. This device has the following disadvantages:

- very limited evolution of surface.

- Poor spatial and dynamic resolution

- very complex processing software - cost solution. Etc.

C - The analysis systems using inertial sensors

The accelerometers are used to perform dynamic measurements of a system. Sensors are placed on the body parts that we want to know their acceleration over time. These assay systems are not in principle subject to referential constraints. The field of development is almost infinite. However, they have the following disadvantages:

- No static measurement is possible; so it is not possible to determine at rest relative position of the feet;

- The mathematical determination of the position of the sensor in space requires a double integration of the acceleration signal which is known as a constant. In addition, this double integration introduces important drifts due mainly to the vagueness of piezoelectric sensors and amplifiers. For this reason, the position can not be determined in the short term.

Among the devices which are the measurement of acceleration are:

• The European Patent EP 1066793 A2 FYFE Kenneth R FYFE Kipling W. ROONEY, James K. of July 4, 2000.

• US Patent 2002/0040601 A1 FYFE Kenneth R FYFE Kipling W. ROONEY, James K. April 11, 2002.

D - son to locometer Des son purposes are attached at one end to the legs (pins) of the subject.

The other end is wound in the manner of a reel about the axis of rotation of one or more potentiometers or tachometer. The bodies of the potentiometers are attached to a base fixed to the ground. During operation, the traction son rotates potentiometers that recognize a number of turns proportional to the distance traveled. This type of device is particularly simple, accurate, reliable and inexpensive. However, it has the following disadvantages:

- Scope limited changes (a few meters)

- On straight in the axis of the reels, imposed - directional ambiguity. Pulling the son can be obtained in various ways.

- The distance between the feet is not measured, etc.

Different walking analysis systems described above relate their measurements directly to a fixed reference frame generally attached to the evolution space. The invention particularly relates to a method and an embedded standalone device capable of solving the problems set forth above, without using the laws of dynamics that govern the forces and accelerations.

According to the present invention, this object is achieved by a method which comprises carrying out alternately measures for each object or body, the other object or device being taken as a reference measure.

According to an advantageous example of implementation of this relative reference method, measuring the length of the line that connects both assigned reference points, respectively, to each of the two objects or moving parts, and each position is determined from these past in relation to this right.

According to very advantageous application of the invention to kymographique Gait analysis was measured on the one hand the length of the straight line connecting two points of reference respectively attached to right and left feet of the subject and, hand, the angles between said line and each of the two feet, so as to obtain, without ambiguity, the relative position on the ground of both feet. It will be shown later that one can also reconstruct the path of the succession of foot supports that characterize walking.

The autonomous device according to the invention is characterized in that it comprises two complementary units able to perform on the one hand, the measurement of the length of the chute between two reference points assigned respectively to two objects, when placed at a distance from each other, and, secondly, measuring at least one angle of this line with respect to a plane which originates at least one of the ends of said right.

One of the big advantages of the invention lies in the fact that the field of evolution is almost unlimited. Another advantage is inherent in the accuracy of any differential measurement. It is much better effect when it is on only when the result of a difference of absolute measurement.

The objects, features and advantages above, and still others, will become clearer in the following description and accompanying drawings in which:

1a is a schematic floor of the relative position of two objects designated by G and D which are also the origins of their repositories. From the measurement of the length of GD straight line I connecting said reference and angles β and one can infer the coordinates of D in the repository of coordinates G and G in the repository D. Referring to a Cartesian orthonormal original G with a horizontal axis carried by the normal to the long side of the object G and an axis of ordinate parallel to the long side, the measurement e is the abscissa and D is the ordinate D in the G repository

1b shows an exemplary timing diagram showing schematically the evolution of the variables α, β and I over time and the distance traveled by each foot of a subject during a normal operation. The relative position of the feet in the double support phase (both feet are in contact with the ground) is shown by plateaus where α and β are maximum absolute value, derived is then zero. In this illustration, the legs move together so that I is minimum when α = β = 0.

2a shows the objects "G & D" which are respectively linked oriented angles α and β and the agreement they sign. With this agreement, we can easily identify the climber as one where the angle attached believes in algebraic value as that of the foot in motion decreases.

Figure 2b shows the relative positions of objects "G & D". The object D is an angle α + β according counterclockwise with respect to the object "G". The α and β signs being determined according to the convention of Figure 2a. Figure 3 shows an example of successive investments in two trajectories arcs objects "G & D" in alternate movement that have their origins in an absolute coordinate system initially confused with that of G. The evolution of objects "and G D "is made in this example according to increasing x. Successive measurements of space vectors and angles attached to investments related objects "G & D" used to calculate the space vectors related to absolute reference G or D.

Figure 4 shows the method of determining the successive coordinates of G and D in an absolute reference frame allowing to trace the path of the objects' G and D "Figure 5 illustrates a method for determining according to the invention the relative positions of objects "G and D" using two transmitters (1 and 2) and two receivers (3 and 4) to ultrasound. In this example, transmitters and receivers are placed with a gap (e) known on the objects G and respectively D. The transmitters 1 and 2 emit ultrasound wave trains in sequence which are received by the receivers 3 and 4. The flight time of the wave train emitted by the transmitter 1 for measuring the respective distances between 1 and 3 and 1 and 4. While, when the transmitter 2 is activated it is the distance between 2 and 3 and between 2 and 4 which are measured. Of these four steps, it is easy to unambiguously determine the relative position of objects "G & D". In this illustration, the circle C1, the point of equal distance R1 between 1 and 3 intersects the radius R2 of the circle C2 which is the distance between 2 and 3. The position of 3 with respect to the object G is determined without ambiguity. By applying the same method on 4, fully determining the D position with respect to G.

6 shows another method of determination according to the invention the relative position of objects 'G and D' based on the measuring magnetic field emitted by an embedded transmitter 5. The magnetic sensors 6 and 7 are capable of measuring their relative position in the six degrees of freedom of the space relative to the transmitter 5. The relative position of sensor 7 with respect to the sensor 6, for example, is easily deduced by a calculation difference of the coordinates, relative to 5, 6 and 7.

Figures 7, 8 and 9 respectively show a top view, a front view, and a method of fixing a device according to the invention, particularly cheap, for the study of a straight-ahead at a distance constant foot. Under these conditions, one angle (α or β) is required to calculate the characteristics of not from the sign and magnitude of the angle (β in this example). The connecting rod 15 to the radial axis 14 of the angular encoder 13 is aligned by rotation about 14 in the direction of the tension of the elastic thread 12 attached to the ends 11 and 14. Figure 7 shows two positions of the left foot with respect to right foot: a rear G in position with an angle βi <0 and a forward position with an angle β> 0. d1 represents the length of not right relative to the left foot and the length d2 of the step left relative to the foot law

10 shows the simplified shape of the evolution of the angle β, its derivative and not a function of time. Figure 11 shows a more sophisticated embodiment than that of Figure 7 in that it allows through two angular encoders (13g and 13d) respectively secured to the left and right foot, for the α and β angles. This embodiment applies to the case of a walking distance of the feet maintained constant according to any one path.

Figures 12 and 13 show a top view and a front view of a device according the invention capable of providing a straight 12 materialized by the thread 12 of inextensible measurable length I and the α and β angles. In this embodiment, the housing 8 (attached to left foot) carries an angular encoder of the angle α, 13g and a counter wire 18. These two devices together to provide on the one hand the length of the wire around the pulley debited 16 under the action of traction of the housing 9 and on the other hand the angle α between the wire stretched by the return spring 19 and the housing 8. the housing 9 has the angular encoder of the angle β, 13d . All (8 and 9) is an embodiment according to the invention particularly cheap capable of measuring the characteristics of the market in all circumstances.

Referring to the drawings to describe interesting examples, although not limiting, implementation of the method and embodiment of the self apparatus for determining the relative position of two objects, according to the invention.

As stated previously, is described below, in a simplification, only applications of the invention to the analysis kymographique walking. Under these conditions, the words "right foot" and "left foot" used in the remainder of this paper have no restrictive nature, the invention can be applied to the analysis kymographique other organs or other objects moving.

If there is shown to simplify the feet by two rectangles (Figure 1a), call: I the length of the line that connects them with the G and points D, α the angle of said straight line with the line normal to the longitudinal axis the left foot at the point G and the angle β with the line normal to the longitudinal axis of the right foot at the point D.

The distance d between two foot rests (stride length) is given by the formula: d = l.sinus (α). The spacing e between the two feet is given by e = l.cosinus (α). The graph in Figure 1b illustrates by means of a timing diagram of four steps the principle of obtaining the route depending on the time points D and G respectively attached to right and left foot. Those skilled in the art readily understand that only three parameters (I, α and β) to have at any time the ground projection of the provision of both feet, not by accumulating easily determining the distance traveled by each foot and the path of the walker. But it is easy to translate in space, it is sufficient to define and measure for this two other angles that are the pitch angles (about the transverse axis of the foot) and roll (around the longitudinal axis of foot). The angles of the ground supports (α or β) being yaw angles (around the line perpendicular to the plane defined by the longitudinal axis and the transverse axis).

The origin of the invention has in fact his idea of ​​walking characteristics in the biped for example which is carried out by sequential and timed phases. The pitch: it is the action of getting the support of the body from one foot to the other. The stride of the right foot support on the left foot and vice versa. So that only one foot is moving while the other bears. It is this feature that tracks the path of the walker from relative measurements. Just set from the origins of reference of both feet against a reference associated with the evolution of space (the floor for example). Based on these considerations, the measurement reference is not necessarily attached to a fixed base. It can be embedded.

To demonstrate the feasibility of the process according to the invention, we adopt the convention (2a) below: in the coordinate system of one of the two feet, the angle (α or β) of the geometrical line connecting the other foot is counted positive in said index if said right is directed to the forefoot. It is counted negative if said right is directed toward the heel. With this convention, each new step (ongoing support), realized with the support foot an α + β angle. In the example of Figure 2b, the support foot is left and the right foot is in progress; α is positive, β is negative, of absolute value greater than that of α. The right foot is rotated in the anti-trigonometric direction to the left foot.

In its evolution, the walker, sends a sequence of vector-space Vi (Figure 3) whose origin part of the supporting foot and the foot end terminates in progress. The sequence of said vectors determines the route. Each space-vector Vi is perfectly determined according to the invention in the reference of its origin. The method for determining the coordinates of each vector in an absolute reference (attached to the ground, for example) is given in Figure 4. In this illustration, the mark left foot support (original G 0) is confused, but not necessarily the absolute reference. The vector G 0 D 0 has coordinates (abscissa and ordinate) 0 xd, yd 0 measured by the data length of said vector (module) and the angle α 0. The vector ^ DoG has the coordinates x '0 and y' 0 in the original mark. Said marker is rotated by an angle R f = α 0 + βo relative to the reference of the previous vector, in this case, it is also with respect to the absolute coordinate system. The coordinates of G_ in the absolute coordinate system are given by the following equations of transformation well known reference (translation + rotation): xg-i = xd 0 + xOcosR yOsinR-i y i = y d 0 + x '0 sinRι + yOcosR-i

The same transformation method is applied to the i-dD vector whose origin mark is rotating, + β, with respect to reference vector DOGI and rotationally R 2 = R, + α-ι + β_ β = 0 + 0 + a_ + βi relative to absolute reference. We get: xdi = xgι + X 'I COSR 2 - y' 1 = SINR 2 ydi YGI x'ιSinR + 2 + y '2 1 COSR

The recursive method described above therefore makes it possible to trace the locus of the ends of successive vectors in a particular frame of reference, and thus the path the walker. Furthermore, all the characteristics of travel (speed, stride length, frame rate, asymmetry not, support phases, swinging, etc.) are also measured. In a different area than the study of walking, it can be interesting to investigate the contours of a surface or a free-form. It would be enough for it to move objects "G & D" alternately along the contour to evaluate. An application of the above principles is the system of the invention which consists of at least two devices in solidarity with two (or more) items that we want to know the relative positions. For simplicity we reason on the relative positions of two solids in a plan - for example- the ground. But it is easy to transpose into space, simply define and measure it to two other angles. The set of two devices cooperate to measure, on the one hand, the length of the straight line which connects them and, secondly, measuring at least one angle of said line with respect to a plane which resulted one end of the right. In several embodiments of the invention, the right is immaterial (laser, ultrasonic, microwave system, magnetic field etc.), it is determined by a wireless method of triangulation or telemetry, comprising at least a transmitter or transceiver and at least one receiver of the waves emitted by the latter. In one implementation of the method and of the self apparatus according to the invention (Figure 5), is fixed by an unillustrated suitable method, two ultrasonic transmitters 1 and 2, with an arrangement and spacing known e on one of the two solids (G in this representation). On the other solid D, is fixed, with an arrangement and spacing known two ultrasonic sensors 3 and 4 operating at the same frequencies that the transmitters 1 and 2. In this embodiment, the ultrasound emissions from transmitters 1 and 2 are activated sequence. The sensors 3 and 4 receive the alternating emission of 1 and 2. In the transmitter 1 transmission time is measured by a well-known telemetry methods (time measurement runs or phase difference between the transmitted signal and the signal received), distances between 1 and 3 and between 1 and 4. During the transmission time of the transmitter 2, measuring the distances between 2 and 3 and between 2 and 4. with this measuring principle, unambiguously known the relative position of the detectors 3 and 4 with respect to the transmitters 1 and 2. A simple calculation then possible to deduce the geometrical line connecting the two solid angles and it defines with respect thereto. To emphasize the unambiguity of the measurement, trace the circle C1, locus of equal distance R1 between the transmitter 1 and the receiver 3. Setting a circle C2 of radius R2 representing the distance between 1 and 4. The cut-off point of the circles C1 and C2 to determine the position of the receiver 3. The same method as used to determine the position of the receiver 4. For a variant of the previous embodiment, incorporating a device for measurement of angles in two directions in space in a different application than that of the invention, reference may be made to the publication: A. Rollero, Oυaknine M. et al. Two-Axis Ultrasonic Detector rotation, IEEE Transactions On Biomedical Engineering. Flight. 37. No. 5. May 1990 p 450-457.

In another embodiment particularly sophisticated, for which one wants to know, for example, at any time in a walker, the 6 degrees of freedom of the two feet (3 translations and 3 rotations) can advantageously benefit from commercial devices such as the system of measuring position and orientation "the Flock of Birds®" society Ascention Technology Corporation (USA) whose measurement principle is based on the transmission of a pulsed magnetic field that is simultaneously measured by a or more sensors. Each sensor independently calculates its position and orientation. However, the range of such a system is limited to about 1, 5 meters, and the transmitter is too heavy to be attached to one of two feet. It may however either be worn by the subject, for example at the belt or be carried by a device moving with the subject - on a carriage for example-. And embedded at a distance less than its radius of action, the system can easily determine according to the principles mentioned above, the parameters (right angles) required for gait analysis. 6 illustrates the method of determining said parameters. The transmitter 5 is worn by the subject. The sensors 6 and 7 are set to toe G and D. At any time, the device measures the coordinates and rotations sensors 6 and 7 with respect to the transmitter 5. To understand the method, we will reason in a projection ground. The length I of the GD line is given by Pythagoras:

Figure imgf000013_0001
The following angles are calculated by trigonometric relationships:

Figure imgf000013_0002

The magnetic device is, as we said, can measure three angles of space for each sensor. Therefore, it provides: φg and φd respectively represent the rotation of the sensor 6 and 7 with respect to the transmitter 5. These angles are oriented, and, according to previously established conventions, one can easily verify the following relations: = θg-β φg? - = - & (£ ._- θd + φd) the three elements (I, α, β) calculated in the mode of determining the path is the same as that already explained above.

In the embodiments that follow, the geometrical line is materialized, it mechanically connects G and D solids while allowing the expression of their movement. Their achievements are the invention of increasing complexity according to the requirements of the analysis and the experimental conditions of the march.

Thus, if the experimental conditions require about a straight walking with a width adjustment Constant-setpoint being, for example placing the feet along two parallel strips, e spacing, labeled sol, it suffices to know a one of the two angles (α or β), since they are equal (alternate interior angles), to determine the dynamic parameters of each step. In this case, the pitch length d = e.tangente (α). The signs of alternating (α or β) mark changes not. Under these conditions, Figure 7 (top view) and Figure 8 (front view) illustrate an embodiment according to the invention particularly inexpensive. According to this embodiment, there are two brackets. The support 8 is for example attached to the left foot and the support 9 to the right foot. The fixing method is not specified here, but it can be for example an adhesive strip 10 or other quick and convenient means such as a self-close fastening tape of the Velcro type (registered trademark). For this use, the mounting location is at the foot, preferably the heel as figuratively (Figure 9), but not necessarily, the inner edges of the feet may also be suitable. The supports 8 and 9 are, for example constituted by brackets or sheet of sufficiently rigid plastic material. The bracket 8 supports, on its horizontal bottom, a shaft 11 freely rotatably mounted or fixed. Said rod has, in this embodiment, a role of an anchor. The bracket 9 supports an electronic device 13 to rotate with a rotary member such as a shaft 14 and capable of providing a signal, for example electric, proportional to the rotation angle of the axis 14 relative to the body the electronic device 13. the device may, for example, be an angular optical encoder, an electronic gyroscope, a potentiometer or other device encoding a rotation angle. The rod 11 and the rotation axis 14 are joined by an extendible wire 12 which may be a spring whose tension is sufficient to define a straight line without interfering with the movement of 8 and 9, so that if one moves in the direction antero -postérieur a support (8 or 9) with respect to each other, the wire 12, due to its tension, rotates the axis 14 until alignment of its point of attachment on the connecting rod 15 integral with said axis. This alignment is facilitated by said rod fixed transversely on the axis 14 and which is operable to increase the torque and to overcome friction of said axis. Figure 7 shows the position of two supports of the left foot with respect to the right foot which perform the β- angles (negative) and β 2 (positive) measured by angular encoder 13. The graphs of Figure 10 clearly show that one can not separate the right foot: dj = e.tangente (β 1) and the pitch of the left foot: d 2 = e.tangente (β 2) with the aid of alternating the angle β and that of its derivative β. Stable support phases coincide in fact with the phases in which the derivative β '= 0.

In a variant of the previous embodiment, the devices 8 and 9 are identical. This variant (Figure 11) of interest to the analysis of a step according to any one path but with a spacing kept constant feet. The coders 13g and 13d of the support 8 of the carrier 9 cooperate to provide the α and β angles from which we can determine the translation and rotation of a foot relative to the other. For gait analysis without burden to the subject, it is necessary to complete the previous embodiment, according to the invention, by a device capable of providing the application and measuring the length of yarn 12 required for connecting the two devices (8 and 9) while ensuring a sufficient tension to rotate the angle encoders 13g and 13d. One solution would be to use an expandable wire whose electrical properties are changed when it is stretched. The carbon foam for example see their son electrical resistance increase with traction. Another solution is to wind the wire 12 which is flexible but not elastic end, around a spool capable of unwinding a length of wire needed while maintaining the tension by a return mechanism which may be for example a spring spiral or a constant torque motor. By mounting said spool on the spindle of an angle encoder, a tachometer or a potentiometer, one can deduce the length of unwound wire. The variant in Figure 12 (top view) and Figure 13 (front view) illustrates an embodiment wherein the wire 12 is rewound around a spool 16 which is integral with the shaft 17 of an encoder angular 18 capable of measuring a number of revolutions and a residual angle proportional to the length of unwound wire. The wire 12 is held in tension by a spiral spring 19 which exerts a torque which opposes its unwinding. Said spring is fixed on the shaft 17 at its central end, and the body 18 at its peripheral end. At its outlet, the thread 12 is guided in a radial direction to the axis 17 by a guide 20 integral with the shaft encoder 18. The body of the angle encoder 18 is free to rotate on the support 8 through a second angular encoder 13g which the axis of rotation 21 is fixed to the bottom of the holder 8. the body of the encoder 18 and the encoder 13g are secured by any bonding mode represented by the plate 22. the lateral forces exerted on the guide by the tension of wire 12 rotates the body of the encoder 18 as the wire 12 is always tensioned in the same direction as the tangent of its separation point on the coil 16. a voltage change in the direction of the yarn, not rotationally drives that axis 17, a change in the direction of the wire rotates the body of 13g encoders and 18 relative to the axis 21. the embodiment according to the invention described above is capable providing the 3 parameters (I, α and β) to allow a number analysis No restrictive walking.

Claims

1. A method for determining the relative position of two objects or bodies moving in a plane or in space, for example applicable to the kymographique gait analysis, characterized in that is carried out alternately, measurements on each subject or body, object or body other being taken as reference measurement.
2. An independent device for determining the relative position of two objects or bodies moving in a plane or in space, for example applicable to the kymographique gait analysis, characterized in that it comprises at least two input devices (1, 3; 2, 4; 8, 9) capable of carrying out, firstly, the measurement of the length of the straight between two reference points (D, G) attached respectively to the two objects, when they are placed at a distance from each other, and, secondly, measuring at least one angle (α, β) of this straight line with respect to a plane which originates at least one of the ends of said straight.
3. A method relating repository according to claim 1, characterized in that the length is measured from the right side (DG) which connects the two reference points (D,
G) allocated respectively to each of the two objects or moving parts, and the position of each is determined of the latter with respect to this line.
4. The method of claim 3, characterized in that one measures on the one hand, the length of the straight (DG) which connects the two reference points (D, G) attached respectively to two objects or bodies , for example the right foot and left foot of a subject, and, on the other hand, the angles (α, β) formed between said straight line and each of said legs.
5. Method according to one of Claims 3 or 4, characterized in that the measuring the length of the line (DG) by means of complementary telemetry apparatus comprising at least one transmitter (1, 2) and at least one detector (3, 4) attached respectively to objects or moving body.
6. A process according to any of claims 3 to 5, characterized in that the measuring the length of the line (DG) by means of complementary telemetry apparatus comprising two transmitters (1, 2) and two detectors (3 , 4) fixed, respectively, with a position and a given distance (e) to the objects or moving body, the transmitters (1, 2) emitting in alternation and each receiver (3, 4) being tuned in frequency to one said transmitters (1, 2).
7. Method according to one of Claims 3 or 4, characterized in that the measuring the length of the line (DG) by a wire (12) of variable length connecting the objects or bodies in motion, and in that there is the length variations of the wire by means of at least one device (13-14) attached to at least one of the objects or bodies and capable of measuring length variations.
8. An independent device according to claim 2, characterized in that said additional devices comprise, firstly, a transmitter or transmitter (1, 2) of light waves, or ultrasonic waves, or radio waves, or magnetic field and, secondly, at least one receiver (3, 4) tuned to said transmitter, for generating a light line (DG) between transmitter and receiver.
9. An independent device according to claim 2, characterized in that said additional devices comprise at least two spaced apart transmitters or emitters (1, 2) and at least two spaced receivers (3, 4), said transmitter being subject to a device for activate alternately.
10. An independent device according to Claim 2, characterized in that it comprises a wire (12) of variable length, whose ends are fixed to said input devices (8, 9), at least one of these devices being arranged to measuring the variations in length of said wire when tensioned.
11. An independent device according to claim 10, characterized in that one end of the wire (12) is fixed to a rotary member (14) of an electronic device i (13) known per se, capable of encoding an angle of rotation.
12. An independent device according to Claim 11, characterized in that each end of the wire (12) is fixed to the rotary member means (13g, 13d) capable of encoding a rotation angle.
13. An independent device according to claim 11, characterized in that the rotary member is constituted by a coil (16) mounted on the rotary axis (17) of an angular encoder (18) and on which can be wound the wire (12), said coil being secured to means for unwinding a length of said wire (12) while maintaining the tension by a return mechanism (19), the body of the angular encoder (18) being free to rotate and being provided with a guide between which the thread (12) at its output of the coil (16).
14. autonomous device of claim 13, characterized in that the tensioning means and for returning the wire (12) is constituted by a spiral spring (19) fixed on the one hand, to the axis (17) of the encoder angular (18) via its central end and, on the other hand, the body of said angular encoder (18) via its peripheral end.
PCT/FR2004/000806 2003-04-07 2004-03-31 Method and independent device for the determination of the relative position of two objects moving on a plane or in space WO2004091399A1 (en)

Priority Applications (2)

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FR0304300A FR2853221B1 (en) 2003-04-07 2003-04-07 Method and device for the autonomous determination of the relative position of two objects moving in a plane or in space
FR03/04300 2003-04-07

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FR2896401B1 (en) * 2006-01-25 2008-10-17 Andre Maurice Ouaknine Device and method stabilometry postural REALIZED BY automatic determination of the position of the feet coupled to a tensile properties of the ground pressures podal
US7724610B2 (en) 2007-09-18 2010-05-25 Honeywell International Inc. Ultrasonic multilateration system for stride vectoring
US8078401B2 (en) 2007-09-18 2011-12-13 Honeywell International Inc. Method of personal navigation using stride vectoring
US7943874B2 (en) 2007-09-18 2011-05-17 Honeywell International Inc. Ground contact switch for personal navigation system

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FR2853221B1 (en) 2005-10-14

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