Method of investigating the gait of a living being

• US 5,186,062 A
• Filed: 03/30/1990
• Issued: 02/16/1993
• Est. Priority Date: 05/19/1988
• Status: Expired due to Fees

• Current Assignee: Standard St Sensortechnik AG
• Original Assignee: Standard St Sensortechnik AG
• Inventors: Roost, Walter
• Primary Examiner(s): Noland, Tom
• Application Number:
  US07/455,397
• Time in Patent Office: 1,054 Days
• Field of Search: 73/865.4, 73/862.04, 73/862.64, 73/862.65, 73/862.66, 73/862.67, 73/380, 73/381, 73/379, 128/779, 128/782
• US Class Current: 73/865.4
• CPC Class Codes: A61B 5/1038 Measuring plantar pressure during gait

Abstract

The force exerted on a measuring section is broken down into two components each acting on one end of a measuring section. The components are each broken down into a vertical part and a horizontal part. The two vertical parts obtained are measured separately. The measured values are cyclically interrogated in an interrogation sequence in the direction of movement of the living being and stored, to permit the determination of force, location, duration and course in time. The measuring surface is subdivided lamellar-fashion at right angles to the direction of movement. One measuring section is narrower than the foot and longer than the track width. The force sensing device (3) comprises a rigid crossbeam which is borne on a sensing block (7) on both sides and acts in the vertical direction on a measured value delivering sensor (23) disposed therein. The crossbeam is mounted to move only vertically and borne on a measuring spring (43) which bears against the sensing block and is preferably a flat spring. The measured value delivering sensor measures the vertical movement of the measuring spring. A transmission element (47) is disposed between the measuring spring and the measured value delivering sensor and is acted upon in the direction of the measuring spring.

Claims

1. A method of investigating the gait of a living being having feet by measuring the force exerted by its feet on the ground and of the location, duration and course in time of the application of force in a zone of a substantially horizontal measuring surface taking the form of part of the ground, the measuring surface being subdivided substantially at right angles to the direction of movement of the living being into elongate measuring sections parallel to each other and adjacent in succession in lamellar fashion, said method comprising the steps of:

(a) measuring the force exerted by the living being on a measuring section an dividing the force exerted into two components, one of each component acts on the measuring section adjacent a respective end thereof;

(b) breaking the two components into a vertical and a horizontal part resulting in two horizontal parts and two vertical parts;

(c) measuring the two vertical parts separately to obtain a measured value for each of the two vertical parts; and

(d) cyclically interrogating the measured values in the course of an interrogation sequence corresponding to the succession of measuring sections in the direction of movement of the living being, the measured values are put into intermediate storage in an analog measured value store and subsequently compared with a predetermined threshold value, and only those measured values put into intermediate storage which exceed the threshold values are passed on for an evaluation wherein the sum of the two measured values is formed for the determination of the total force exerted vertically on the measuring section and the ratio between the difference in the two measured values and their sum is formed to determine the location where the force is exerted on the measuring section.

2. The method according to claim 1, wherein in order to determine the total force exerted vertically on a measuring section, the sum of the two measured values is formed, such sum is on the one hand put into intermediate storage and on the other hand compared with a predetermined threshold value, and only those values of the sum put into intermediate storage which exceed the threshold value are passed on for evaluation.

3. The method according to claim 2, wherein those values put into intermediate storage which exceed the threshold value are subjected to an analog-to-digital conversion, after an amplification via an analog amplifier, while a digital identification of each corresponding measured value delivering sensor and a digital statement of time are associated therewith, and each value which is being passed on for evaluation is stored together with its identification and its statement of time.

4. The method according to claim 2, wherein the cyclic interrogation sequence is initiated only on the occurrence of a value put into intermediate storage which exceeds the threshold value, and the interrogation sequence is automatically discontinued if during a predetermined period no occurrence has been detected of a value put into intermediate storage which exceeds the threshold value.

5. An apparatus for investigating the gait of a living being having feet by measuring the force exerted by its feet on the ground and of the location, duration and course in time of the application of force in a zone of a substantially horizontal measuring surface taking the form of part of the ground, said apparatus comprising:

(a) elongate measuring sections, the measuring surface being subdivided substantially at right angles to the direction of movement of the living being into elongate measuring sections parallel to one another and adjacent in succession in lamellar fashion, the width of each of the measuring sections being smaller than the length of the foot of the living being and the length of each of the measuring sections being greater than the track width of the living being;

(b) a plurality of measured value delivering sensors connected to an electronic evaluating unit associated with each measuring section, each of the measured value delivering sensors being a path sensor for vertical movement of a measuring spring;

(c) a force sensing device having a substantially rectangular force sensing surface and comprising a stiff cross beam having an upper surface on which the measuring section is disposed, the cross beam borne on a lower surface thereof at opposing ends thereof, each end on a sensing block so as to act therein in the vertical direction on one of the plurality of measured value delivering sensors, the cross beam in the force sensing device mounted to move substantially only vertically and borne on a measuring spring which bears against the sensing block; and

(d) a transmission element for the vertical movement of the measuring spring disposed between the spring and each of the plurality of measured value delivering sensors, the transmission element being operatively connected to each of the plurality of measured value delivering sensors and acted upon by a resilient means in the direction of the measuring spring.

6. The apparatus according to claim 5, wherein the measuring spring takes the form of a flat spring and is so disposed in the sensing block that its bending is limited by its coming into contact with a stationary part of the sensing block, the transmission element being substantially vertically extending and having a rod section and a tappet rod adjoining a bottom end of said rod section and a sliding member adjoining atop end of such rod section, the sliding member being guided in the vertical direction in a guide sleeve provided in the sensing block and having in an upper portion thereof a head which is engaged from below by a sealing disc bearing against the sensing block and comprises an adjusting device in which a top end thereof has a receiving depression for a bottom part of a ball whose top having a top part which bears against the measuring spring.

7. An apparatus according to claim 6 wherein there is disposed between the crossbeam and the measuring spring a ball which is trapped in a matching ball receptacle in the sensing block and is borne on the measuring spring substantially in its center, the measuring spring being mounted on two rollers which are spaced from one another and symmetrically from the center of the measuring spring and are disposed substantially parallel with one another and at right angles to the longitudinal direction of the measuring section, one roller being stationary in relation to the sensing block and the other roller being movable.

8. The apparatus according to claim 7 wherein the sensing block contains a rail strip in which the measuring spring and the ball are received and which is engaged from above in roof fashion by a U-shaped sectional strip provided on the crossbeam.

9. The apparatus according to claim 6 wherein the measured value delivering sensor comprises permanent magnets, magnetically sensitive sensor elements and attaching elements, the attaching elements being made of a resilient material and movably retaining the sensor elements and having a resilient pre-stressing which acts on the sensor elements in the direction of the tappet rod.

10. The apparatus according to claim 5, wherein the crossbeam is mounted in the force sensing device on at least one beam extending upwardly from the sensing block and is connected to such a beam via a substantially horizontal spring strap, and the force sensing device is inserted in a groove, the sensing blocks each being attached in two parallel rows to a foundation section, let into the bottom of the groove, by means of threaded bolts and clamping blocks connected to the foundation section, such clamping blocks having lugs engaging in grooves in the sensing blocks and being so disposed offset in relation to the sensing blocks that fastening screws associated with the clamping blocks are accessible to a screwdriver inserted from above between the measured value delivering sensors inserted in the sensing blocks.

11. The apparatus according to claim 10, wherein a number of force sensing devices are disposed together on an auxiliary assembly frame, the clamping blocks being connected via the attaching screws to the auxiliary assembly frame, and the latter and the individual sensing blocks being connected via the threaded bolts to the foundation section.