A DEVICE FOR DETECTION OF RELATIVE MOVEMENTS AND/OR POSITIONS OF A PART OF THE BODY OR THE LIKE

Abstract: Device for detection of relative motions or positions of one or more parts of the body, comprising at least two measuring sensors which are applied onto the part/parts of the body the motions/positions of which are to be measured, at which signals are emitted to a signal processor for storing and/or analyzing. The measuring sensors (1 a-d) are placed in connection to the fulcrums of a parallelogram action linkage (5, 6) attached to the parts of the body the relative movements or positions of which are to be detected and where the imaginary axes about which some of the mentioned motions takes place form a part of the parallelogram action linkage.

Description: A DEVICE FOR DETECTION OF RELATIVE MOVEMENTS AND/OR POSITIONS OF A PART OF THE BODY OR THE LIKE. The present invention relates to a device for detection of relative movements or positions of one or more parts of the body, comprising at least two measuring sensors which are attached to the part/parts of the body the movements/positions of which are to be measured, at which signals are emitted to a signal processor for storing and/or analyzing. BACKGROUND OF THE INVENTION There is a great demand for studies and analyzes of body movements during different working moments, e.g. in the industry. The most important reason is to prevent pains and injuries, e.g. in the back and the neck, where they are very frequent. Another reason is that the law of "occupational injury insurance" requires that mechanical stresses, that a person have been exposed to in an occupational injury, have to be estimated. Today, it is common that physiotherapists or industrial hygienists visit working places and study in which way t h e different working moments are performed, and thereby the knowledge is increased and makes it possible to take steps to decrease the presence of injuries and pain, which is . jery high in different exposed working places. By studying for example how many times and for how long a part of a bo d y is in a s p ecial position, a base is obtained to give the size o f the stress for different working moments and this makes it possible to give advices or restrictions for the working momen . THE PRIOR ART Many devices for detection of movement or position of a part of the body are known today. These are based on d ifferent re g istration techniques. For exampel, film-cameras or vi d eo cameras can b e used for registation of a working moment. But t h e evaluatin of the film is quite time- and work-comsuming. Important limitations also appear when the film is taken why the technique can be used only in a few cases. Another known technique is based on opto-electronics , where e.g. an infrared-camera is used to detect a number of points of lights - which are attached on the object. Because of the disadvantage that the points of light have to be exposed to the camera all the times, this method is not suitable for measurements in real working places where some movements might be hidden by machines or likewise. The evaluation in this case requires also a lot of work. The most suitable technique for detection of movements or positions of a working person (the test object) is the gonimeter technique. This technique means that some kind of sensing member is constructed, e.g. an angular sensing member, which physically detects the movements o.r the position of the part of the body and converts this to e.g. an electrical signal which is proportional to the movement or position. The quantity of information is processed/reduced in order to make it possible to present it in an easily readable way. An example of the gonimeter technique is described in the Swedish patent no. 7909887-7 which present a device for measuring the position of a part of the body in relation to the earth gravitation. It is not possible to measure e.g. the bending of a part of the body in relation to another, with this device. Another registration device is shown in the U.S. patent no. 4.306.571. Herein, a three-planer measuring device comprising three potentiometers which are arranged to measure the rotation of a knee in three axes or planes is described. For exampel, square shafts are used for mechanical transmission of torsional or rotational movements. But the fiel d of application for this invention is not the same as for the p resent invention, namely to make measurements of a knee which is only one joint and cannot be compared with a complex system like a back, a neck, etc. In the U.S. patent no. 4.436.099 there is further shown a measuring device which is suitable e.g. for measuring of angular changes between a person's upper arm and forearm. With this device it is possible to measure the angular movements only in one plane, which movements are converted in optical way by a disc having segments of different colours, said disc being caused to rotate in either direction. The apparatus cannot be used for detection of movements of the back and the head . OBJECT AND FEATURES OF THE INVENTION The object of the present invention is to provide a device for detection of relative motions or positions of a part of the body, and in which device the aforementioned disadvantages are eliminated, and which makes simple and accurate measurings even of complicated movement systems such as the back , neck or likewise possible at a relatively low cost. The invention is provided by the fact that the measuring sensor is placed in connection to the fulcrums of a parallelogram actiύ ' n linkage attached to the parts of the body the relative movements or positions of which are to be detected, and where the imaginariy axes around about which one or some of said movements are performed make a part of the parallelogram action linkage. DESCRIPTION OF THE DRAWINGS The invention will in the following be described with reference to an embodiment shown in the accompanying drawings Fig. 1 a-f shows the different types of bending/rotations which the present invention is intended to measure Fig. 2-5 shows an embodiment of the measuring device according the invention seen from different views. Fig. 6 shows a schematically a block diagram of the invention . Fig. 7a shows an exampleof the measuring area for the head rotation, extension/flexion and lateral flexion. Fig. 7b shows an exampleof the measuring area for bending of the back. Fig. 7c shows an exampleof the measuring area for rotation of the back. Fig. 8 shows examples of transcriptions from the measuring device. DESCRIPTION OF AN EMBODIMENT The invention consists of a device for detection/measurement of relative movements or positions of a part of the body. In fig. 1 a-f is illustrated examples of bendings of the back and the head, which the present invention is arranged to detect. Fig. 1 a-c presents from right to left the flexion and the extension of the head i.e. the bending forward and backward, lateral flexion and rotation, while fig 1d-f from right to left shows the lateral flexion of the back, its flexion, i.e. bending forward, and its rotation. The ' device detects also the time during which the present part of the body takes a certain position or angle. Fig. 2-5 show from different views the measuring device comprising of a transmitter means which consists of potentiometers and transfer means, which adjust the potentiometers after the relative position of the head with respect to the rest of the body. The head's rotation is measured with a potentiometer 1a placed on a helmet 2 to be secured on the head of the test person. The potentiometer 1a is connected to a potentiometer holder 3 which can be adjusted along a rail 4 in the helmet 2, so that the potentiometer 1a is located straight above the coronal suture . The head's extension/flexion is measured with a potentiometer 1b placed in a so called potentiometer joint, where also a potentiometer 1c for measuring the lateral flexion of head and a compensation potentiometer 1d is arranged. The object of the compensation potentiometer 1d is to compensate the discrepancy in the rotation measurement, when the shoulder is raised or moved forward/backward. On the compensation potentiometer 1d there is placed a rotary bar 5, which is pivotally connected to a bar 6, which in its turn is pivotally connected to the housing of the rotion potentiometer 1a in such a manner that a parallelogram action linkage is achieved, where the vertical centre line of the head make one part, and the imaginary axis about which the head's flexion and extension take place is an other part. The potentiometer joint with the potentiometers 1b, 1c and 1d are placed in a rail 8 which is arranged on an yoke 9 inteded to be fastened on the test person's shoulders by means of a harness 10. The position of the potentiometer joint 1b-d is adjustable along the rail 8 by means of a holding means 11. The flexion of the chestback is measured with an inclinometer 1e, e.g. a pendelum sensor, placed on the yoke 9 on the opposite shoulder with respect to the potentiometer joint 1 b-d in a rail 12. A collecting box . for the electrical connections is denoted with 13. Another inclinometer (not shown) for measuring the shoulder's lateral flexion can also bbee aarrrraannggeedd hheerree,, wwhhiiccth inclinometer is -' turned 90 in relation to the inclinometer 1e The rotation of the chestback relative to the pelvis is measured by means of a potentiometer 1f which is displaceable in a rail 15 on the harness 10. A longitudinal line of the rail 15 should be substantially parallel with the spine. To the axle of the potentiometer 1f there is attached a flexible axle 16 which through a balljoint 17 is connected with a plate 26 fixed on a pair of trousers 27, so that the plate 26 is p lace d just on top of the spine on the pelvis. By the fact that the potentiometer 1f is displaceable along the rail 15 the elongation of the back when bended is taken up. The measuring device is applied on the test person in the following manner: The yoke 9 is placed on the shoulders and is secured by means of the harness 10. The potentiometer's 1a holding means 3 is adjusted so that its upper surface becomes horizontal and its position is adjusted along the rail 4 so that the center of the potentiometer 1a is placed just above the coronal suture (corresponds to the auditory meatus) after which it is fixed. The potentiometer joint 1b-d is applied in the rail 8 on the right shoulder (according to the drawings) the inclinometer 1e and the collecting box 13 is placed in the rail 12 on the left shoulder (according to the drawings) as far back as possible and are then ixed. The inclinometer 1e is adjusted to horizontal position and fixed. The bar 5 of the potentiometer joint has a square or another non- circular cross-section and is connected to the bar from the helmet by the fact that it is passed through a bushing 14 rotably mounted to the bar 6 said bushing hawing " an axial hole which has a cross-section corresponding to the bar 5. The potentiometer joint 1b-d is adjusted along the rail 8 so that the bar 5 is situated vertically and just opposite auditory meatus. The bar 5 is thereby displaced in the bushing 14 so that a right angle is provided in relation to the bar 6, whereby its location in the bushing 14,. is fixed. The bar 5 can of course also have a round cross-section and be fixed to the bushing 14 in an appropriate way. The electrical couolinα The signals from the measuring sensors 1 a-f are transferred to an electronic transducer or processing device. This can e.g consist of known technique such as a computer which recieves, stores and processes the incoming measuring data. In the circuit diagram, schematically shown in fig. 6 the way of the signals from sensor 1 to the results written by a printer are shown. An exampleof a print can be studied in figure 8. To all sensors 1 a-f a feeding power from accumulators and a constant voltage set is supplied, here called a sensor feeding aggregate 18. The signals from the sensor 1a and Id, i.e. the sensors for measuring the " rotation of the head and the compensation potentiometer, are transfered to a differential amplifier 19 which detects the difference between the signals, and therby also detects the rotation of the head with respect to the back. Signals from the sensors 1b, c.e.f and from the differential amplifier 19 are sent to a junction box 20, from which signals can be transferred to an instrument tape recorder or a printer 21 for storage and later analysis. The junction box 20 is also electrically connected to an analogous/digital converter 24, an A/D-converter , in which the analogous signals from the measuring sensors 1 a-f are converted to digital signals which thereby are readable for a computer 23. The computer can e.g. have the program stored on a tape recorder 24. In the computer 23 an internal -memory -is arranged. The computer 25 is suitably connected to a printer 27 for printing of the measuring results. Every measuring sensor 1 a-f which are connected to the measuring circuit is detected several times each second. The electronics is so arranged that it only register when a data has been detected several times, i.e the electronics discriminates all measured data which have occured during the "building-up time" of the measuring sensor. Independent of this process, a data is registered every second. However, the analogous signal is sent to and stored in the instrument tape recorder 21. Processing of the measuring data. g In f ig. 8 is shown an example of a print from a measurement p erformed by the device according to the present invention. 0 0 The head's rotation is measured in a 90 -sector with 0 straight forward. The total 180 -sector is graded into sectors according to fig. 7a. The left sector is the upper registrations on the tape according to fig. 8. The measuring area for the head's extension/flexion is divided in the same way as for the rotation, but with the difference 0 that extreme values, sector 7, are situated above 65 . The flexion is the upper registrations on the registration tape. The measuring area for the lateral flexion is the same as for the extension/flexion. Left lateral flexions are the upper registrations . 0 0 . 0 Back bendings are measured in a +5 - -95 sector with 0 straight up. The gradings of the sector are presented in fig. 7b. 0 0 The rotation of the back is measured in a 85 -sector with 0 straight forward. The gradings of the sector is presented in fig. 7c. In fig. 8 is shown a print consisting of a register of the measuring results obtained in a measuring serie. At— the top facts about the test person are written, e.g. name, social security number and so on. Underneith a table is presented where the number of time intervals a certain position, here the back's bending position, has been ' taken. A histogram which grafically illustrates the frequency of the different positions is found under the table. From the table and the histogram one can estimate how injurious the respective working moment is . The following table is constructed as the previous but shows the result of the measurements of the lateral flexion. The two following tables present the number of occasions a certain position simultaneously is taken the at the head's extension/flexion and its rotation. The invention is of course not limited to the above described embodiments but several alternative embodiments are possible within the scope of the claims. It is also possible to adapt the present invention to detect the position of motions of other parts of body, e.g. the arms.

Claims: CLAIMS 1. A device for detection of relative movements or positions of one or more parts of the body, comprising at least two measuring sensors which are applied to the parts. of the body the movements/positions of which are to be measured, at which signals are emitted to a signal processor for storing and/or analyzing , c h a r a c t e r i z e d b y, t h at the measuring sensors (1 a-d) a.re arranged in connection to the fulcrum of a parallelogram action linkage (5,6 ) attached to the parts of the body the relative movements or positions of which are to be detected, and where the imaginary axes about with one or some of said movements are performed makes a part of the parallelogram action linkage. 2. A device according to claim 1 , c h a r a t e r i z e d b y, that a measuring sensor (1a) for detection of the head's rotation is arranged on a helmet (2) or the like arranged to be attached on the test person's head, that measuring sensors (1b, 1c) for detection of the head's extension/ lexion and/or lateral flexion are attached to a shoulder of the test person, and that a first bar (6) - is pivotally connected with the measuring sensor (1a). on the test person's head, said first bar at its opposite end is pivotally connected with a second bar (5), the opposite end of which is rotably connected with the measuring sensor(s) (1b, 1c) on the test person's shoulder. 3. A device according to claim 2, c h a r a c t e r! z e d b y, that the measuring sensor(s) (1b, 1c) on the test person's shoulder make a part of a unity, in which also is comprised a com p ensation potentiometer (1d) arranged to compensate t h e discre p ancy when the shoulders are risen or lowere d orward/backward . 4. A device according to any of the preceeding claims, c h a r a c t e r i z e d b y, that on the test person's opposite shoulder there is attached at least one measuring sensor (1e) for detection of the chest backs flexion and/or lateral flexion. 5. A device according to any of the preceding claims, c h a r a c t e r i z e d b y, that the measuring sensors (1a-e) are attached to holders which are displaceable along rails (4,8, 12) on the helmet (2) , a yoke (9) , a harness (10) or the like attached to the test person's shoulders. 6. A device according to any of the preceding claims, c h a r a c t e r i z e d b , ' that a measuring sensor (1f) for detection of the chestback's rotation with respect to the pelvis is placed on the test person's back just opposite the spine, said measuring sensor (1f) via a transmission device (16, 17) for rotational motion is connected with a part (26) fixed to the test persons pelivs area . 7. A device according to claim 6, c h a r a c t e r i z e d b y, that the measuring sensor (1f) for detection of the chestback's rotation is displaceable along a rail (1 ,) to the harness (10) said rail is arranged substantailly parallel with the spine.

Inventors: NILSSON STEN, NILSSON, STEN
Applicants: SE PRODUKTER, SE-PRODUKTER
Application year: 1986
Main classification: A61B5
IPC codes: A61B5