Force measuring device

Description

technical field

[0001] The present invention relates to a device for measuring a force.

[0002] The invention falls within the field of metrology. The field of the invention is more particularly, but not exclusively, that of measuring force on a potentially very weak patient, for example, the extension or flexion force of a knee, the abduction of a shoulder, or the flexion of an elbow. Prior art

[0003] We know of devices for measuring strength on potentially very weak patients.

[0004] Among these devices, we know of fixed dynamometer devices comprising a force sensor placed between two straps, one of which is fixed to a stationary point (most often a point on a wall structure) and the other is connected to the patient by means of an ergonomic strap adapted to the size of the patient and the size of the limb being tested.

[0005] One technical problem posed by this type of device is that some patients are so weak that they cannot put the sensor and strap under tension.

[0006] The aim of the present invention is to solve this problem.

[0007] Document FR 2 988 838 describes a system for measuring palmar grip strength.

[0008] Document EP 0 083 568 A2 describes a portable manual muscle tester.

[0009] US document 3,680,386 describes a physical therapy diagnostic device.

[0010] Document JP S58 190727 describes a kitchen scale. Document US3577779 describes a force sensor with means for mounting via a threaded hole in the base. Description of the invention

[0011] This objective is achieved with a force measurement device according to claim 1.

[0012] The sensor preferably has an accuracy less than or equal to 0.5N.

[0013] The sensor preferably has a measurement range of at least 0N to 900N.

[0014] The measuring member can be provided with a screw thread arranged to attach to the measuring member an external element extending along the measuring axis through the through hole.

[0015] The device according to the invention may include at least one electronic board arranged to: a shaping of an electronic signal from the sensor into force measurement data and / or a power supply to the sensor and / or other elements of the device, and / or a communication, outside the device, of force measurement data from the sensor, and / or a storage of force measurement data from the sensor.

[0016] At least one electronic card preferably extends: parallel to the measurement axis, and / or under the sensor and under the fixing means.

[0017] According to yet another aspect of the invention, a set comprising is proposed: a device according to the invention, in which at least one electronic card is arranged for wireless communication, outside the device, of force measurement data from the sensor, and a remote means arranged for displaying the measurement data and / or processing the measurement data, said remote means being connected to said device by a wireless link. Description of the figures and methods of realization

[0018] Other advantages and features of the invention will become apparent upon reading the detailed description of implementations and embodiments, which are by no means limiting, and the following attached drawings: there figure 1is a top view of a first embodiment of the device according to the invention, which is the preferred embodiment of the invention, the figure 2 is a perspective view of a side face of the first embodiment of the device according to the invention, the figure 3 is a perspective view of another lateral face of the first embodiment of the device according to the invention, and the figure 4 is a perspective view from below of the first embodiment of the device according to the invention, without its base plate to make visible the inside of the device according to the invention.

[0019] These embodiments are not exhaustive; in particular, variants of the invention may be considered that comprise only a selection of features described or illustrated hereafter, isolated from the other described or illustrated features (even if this selection is isolated within a sentence including these other features), provided that this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, and / or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0020] We will first describe, with reference to figures 1 to 4 , a first embodiment of device 1 according to the invention.

[0021] The force measurement device 1 comprises: fastening means 2, arranged for fixing the device 1 to a support, for example to a bed, any table or a clinic table, a Bobath table, a chair, typically to a leg or frame or edge of one of these elements, a sensor 8, comprising a measuring member 9 (visible on the figure 3 ) arranged to move (relative to the frame of device 1) along a measuring axis 10 and only along this measuring axis 10, said sensor 8 being arranged to measure a force exerted on the measuring member 9 as a function of the displacement of this measuring member 9.

[0022] The fixing means 2 are arranged so that, when the measuring member 9 moves along the measuring axis 10, they exert on a support on which they are fixed an average force carried by the measuring axis 10. In other words, the axis 10 of the sensor 8 coincides with the axis 10 of the fixing means 2.

[0023] The invention has the advantage that the patient does not need to use a strap to compensate for the weight of the sensor 8, which is particularly beneficial for frail patients who have developed, for example, a neuromuscular, neurological, or cardiovascular condition, and / or for elderly people.

[0024] The measuring member 9 of the sensor 8 is movable relative to the frame of the device 1. The sensor further comprises a housing which is fixed relative to the frame of the device 1, and held together with the frame of the device 1 by fixing to the frame between a nut 11 and a washer 12.

[0025] Sensor 8 includes a strain gauge or dynamometer.

[0026] The sensor used 8 is an "SML Low Height Load Cell" sensor marketed by Interface Inc, for example reference SML-200 or SML-300. The preferred sensor 8 has a nominal capacity of approximately 89kgf (200 Ibf).

[0027] Sensor 8 can be calibrated by a process as described in patent FR 2 988 838.

[0028] Sensor 8 has an accuracy less than or equal to 0.5N and a resolution less than or equal to 0.1N.

[0029] Sensor 8 has a measuring range of up to at least 900 N.

[0030] Device 1 is accompanied by a remote display means (not shown in the figures) arranged to display measurement data and / or processing (change of scale, unit, reduction of measurement noise, etc.) of measurement data, said remote means being connected to said device 1 by a wireless link (for example by Bluetooth or Wifi).

[0031] This remote display means typically includes a tablet (preferably touchscreen) or a PDA ("Personal Digital Assistant") or a smartphone or a bracelet with a screen (preferably touchscreen) and intended to be worn on a person's wrist, typically on the wrist of a doctor or physiotherapist or any other medical personnel.

[0032] This remote method allows you to see in real time the value of force generated on sensor 8 and to memorize the maximum value of each test.

[0033] This remote display means also includes a battery (battery life of about ten hours when measuring sensor 8).

[0034] This remote display means further includes means for storing (typically at 50 Hz or 100 Hz) measurement data or the processing of measurement data.

[0035] This remote display means also includes means (USB port or other) for exporting measurement data or processing measurement data to other technical means such as a computer.

[0036] This remote display means (for example a touch tablet) is also a remote control means arranged to control certain functions of device 1, in particular the calibration of sensor 8 of device 1.

[0037] The fastening means 2 include mechanical fastening means, typically clamping means. The fastening means include a vise comprising: two jaws 4, 5 arranged to clamp the support on which the vise is fixed, of which one jaw fixed 4 relative to the frame of the device 1 and one jaw movable 5 relative to the frame of the device 1, rails 3, arranged to guide a movement of the movable jaw 5 relative to the frame of the device 1, a handle 7 and a rod 6, allowing the jaw 5 to be moved parallel to the axis 10 forwards or backwards according to the direction of rotation of the handle 7 and the rod 6.

[0038] Device 1 includes an outer wall 13 (attached to the frame of device 1). The sensor 8 is located inside the outer wall 13 such that the outer wall 13 has a through hole 14 facing the measuring member 9 along the measuring axis 10, the measuring member 9 being located on a face 16 of the sensor 8 such that this face 16 is not in contact with the outer wall 13. This ensures better measurement accuracy.

[0039] The measuring member 9 is provided with a screw thread arranged to attach to the measuring member 9 an external element extending along the measuring axis 10 through the passage hole 14. This external element is typically a threaded rod attached to a hook or loop or any other fastening system connected to a strap which a user or patient must pull or to a rigid rod which a user or patient must push.

[0040] Device 1 comprises at least one electronic card 15 arranged to: a shaping of an electronic signal from the sensor 8 into force measurement data, a power supply for the sensor 8 and the other elements of the device 1, by a rechargeable battery having an autonomy of about ten hours during a measurement by the sensor 8; the card 6 is arranged to control an automatic switching off of the device 1 and the remote display means, after 10 minutes of non-use of the device 1 and this remote means, a wireless communication (typically by Bluetooth or via a Wifi network), to the outside of the device (more precisely to the remote display means), of force measurement data from the sensor, a storage of force measurement data from the sensor 8, a calibration of the sensor, typically controlled by the remote display and control means.

[0041] At least one electronic card 15 extends parallel to the measuring axis 10, under the sensor 8 and under the fixing means 2.

[0042] In more detail, the at least one electronic board 15 includes in particular sub-modules for the power supply and electrical charging of the device 1, including a connector 19 (USB) for connection to an external power supply source to the device 1, a battery, a battery management sub-module, and a power supply regulation sub-module for each element of the device 1 requiring power.

[0043] A diode 18 indicates, when lit (typically green), a correct charge level of the device 1 battery.

[0044] At least one electronic board 15 also includes a microcontroller.

[0045] The microcontroller advantageously includes an EPROM (Erasable Programmable Read Only Memory).

[0046] The microcontroller can be connected to a computer and the remote display means via a wireless connection (Bluetooth or Wifi) as well as via connector 19. A diode 21 is lit (typically red) when the wireless link is faulty or has a connection problem with the remote display means.

[0047] The microcontroller module integrates several components, including RAM, FLASH memory, and an analog-to-digital converter. These components are configured to allow for force measurement calibration. To this end, a computer program is loaded into the microcontroller's memory to perform the calibration and measurements of sensor 8.

[0048] A button 17 allows the device 1 to be switched on and off. A diode 20 is lit (typically green) when the device is on.

[0049] Device 1, just described, allows multiple force measurements on a potentially very weak patient, for example, extension or flexion force of a knee or abduction of a shoulder or flexion of an elbow.

[0050] For example, in the context of an inflammatory myopathy, inclusion body myositis, it has been possible to validate la The quality of device 1 according to the invention for knee extension was assessed by comparing the torques estimated from the reference isokinetic / isometric device System 3 pro from BIODEX with those estimated from a device according to the invention. The results show excellent absolute agreement between the two measurement systems.

[0051] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the invention.

[0052] For example, in a variant of what has just been described, the means of attachment include a suction cup or a magnet or a hose clamp or clipping means.

Claims

1. Device (1) for measuring a force comprising: - fastening means (2) arranged in order to fasten the device to a support, the fastening means comprising fastening means by clamping, comprising a vice comprising two jaws (4, 5) arranged in order to grip the support onto which the vice is attached, and / or a suction cup and / ora magnet - a sensor (8), comprising a measuring member (9) arranged in order to be displaced along a measurement axis (10), said sensor being arranged in order to measure a force exerted on the measuring member as a function of the displacement of this measuring member, the fastening means being arranged so that, during a displacement of the measuring member along the measurement axis, they exert on a support on which they are fixed an average force carried along the measurement axis the device comprising an outer wall (13), the sensor (8) being situated inside the outer wall so that the outer wall is equipped with a through hole (14) facing the measuring member (9) along the measurement axis (10), the measuring member (9) being situated on a face (16) of the sensor so that this face is not in contact with the outer wall (13).

2. Device according to any one of the preceding claims, characterized in that the fastening means comprise a suction cup or a magnet or a clamp band.

3. Device according to any one of the preceding claims, characterized in that the sensor (8) has an accuracy less than or equal to 0.5 N.

4. Device according to any one of the preceding claims, characterized in that the sensor has a measuring range of at least 0 N to 900 N.

5. Device according to any one of the preceding claims, characterized in that the measuring member (9) is equipped with a screw thread arranged in order to attach to the measuring member an external element extending along the measurement axis (10) though the through hole (14).

6. Device according to any one of the preceding claims, characterized in that it comprises at least one electronic board (15) arranged for: - shaping an electronic signal originating from the sensor into force measurement data, and / or - supplying the sensor and / or other elements of the device with electricity, and / or - communicating, to outside the device, force measurement data originating from the sensor, and / or - storing force measurement data originating from the sensor.

7. Device according to claim 6, characterized in that the at least one electronic board (15) extends parallel to the measurement axis (10), under the sensor (8) and under the fastening means (2).

8. Assembly comprising: - a device according to claim 6 or 7, in which the at least one electronic board is arranged for wireless communication, to outside the device, of force measurement data originating from the sensor, and - a remote means arranged in order to display the measurement data and / or to process the measurement data, said remote means being connected to said device by a wireless connection.