A detection unit for position detection, and a method for position detection

Abstract

The present disclosure relates to a detection unit (2) for detection of the position or orientation of a person (25) or a part (1) of the body of said person (25), said detection unit (2) comprising at least a sensor device (8) based on a gyro unit (8) for detecting said position or orientation. In particular, the detection unit (2) is associated with at least one further sensor device (16) for a further physical parameter (p); that the detection unit (2) is configured with measured values (Δp) provided by said further sensor device (16) based on a vertical height difference between the vertical position of the detection unit (2) during use and the vertical position of the heart (26) of said person (25); and that the detection unit (2) is configured for providing said measured values (Δp) as compensation during measurements with said further sensor device (16).

Description

[0001] A DETECTION UNIT FOR POSITION DETECTION, AND A METHOD FOR POSITION DETECTION

[0002] FIELD OF THE INVENTION

[0003] The disclosure relates to a detection unit for detection of the position or orientation of a person or a part of the body of said person, said detection unit comprising at least a sensor device based on a motion sensor for detecting said position or orientation.

[0004] The disclosure also relates to a method for detecting the position or orientation of a person or a part of the body of said person, by means of a detection unit comprising at least a sensor device based on a motion sensor for detecting said position or orientation.

[0005] The disclosure also relates to a method for calibrating a detection unit for detection of the position or orientation of a person or a part of the body of said person, said detection unit comprising at least a sensor device based on a motion sensor for detecting said position or orientation.

[0006] BACKGROUND OF THE INVENTION

[0007] In the field of medical science, there is a need for devices and methods for detecting and determining the position of the human body, or parts or organs of the human body. In particular, such detection can be applied for monitoring human physical activities, or for measuring body movements or for detecting the orientation of persons or body parts.

[0008] It is previously known to use such devices and methods for monitoring physical activities for detecting and preventing a risk for falling, and for controlling the posture of persons and the coherence in position and movement between different body parts, and other similar parameters. For example, it can be helpful to collect information during physical activities in different environments, in order to improve the quality of life and to reduce risks relating to physical activity.

[0009] In order to provide position and orientation detection of the above-mentioned type, certain sensors and detection units based on inertial measurements can be used. For example, it is previously known in this field of technology to use motion sensors such as gyro units, accelerometer units or magnetometer units to measure the position and orientation of an object, including vertical and horizontal rotation. Such sensors are widely used due to their small size and low cost, and and can also be combined with further sensors to improve measurements and accuracy. In this manner, it is possible to detect changes for example related to location, body movement and rotational changes in a three- dimensional space.

[0010] With reference to prior art within this field of technology, is should be noted that the patent document US 2022 / 0330903 teaches an arrangement for identifying near-fall events based on inertial measurement unit data.

[0011] However, there is a need for further improvements of the above-mentioned types of systems. A particular problem which may occur in detection systems of the above- mentioned types relates to need for correct measurements and accurate detection of such body position and orientation events.

[0012] For the reasons stated above, there is a desire to obtain improved and optimized arrangements and methods for measuring and monitoring the position, movement and orientation of human bodies and parts of bodies.

[0013] SUMMARY OF THE INVENTION

[0014] In accordance with the disclosure, there is provided an improved detection unit and corresponding method in which the drawbacks of known devices within this technical field can be overcome.

[0015] For this reason, and in accordance with this disclosure, there is provided a detection unit for detection of the position or orientation of a person or a part of the body of said person, said detection unit comprising at least a sensor device based on a motion sensor for detecting said position or orientation. Furthermore, the detection unit is associated with at least one further sensor device for a further physical parameter. Also, the detection unit is configured with measured values provided by said further sensor device based on a vertical height difference between the vertical position of the detection unit during use and the vertical position of the heart of said person. Also, the detection unit is configured for providing said measured values as compensation during measurements with said further sensor device. Certain advantages are achieved by means of the device according to the disclosure. In particular, it should be noted that by means of the above-mentioned features, there is provided an improved accuracy during measurements of the relevant physical parameters.

[0016] According to an embodiment, the measured values (Ap) are based on measurements of said further physical parameter with the person first being generally horizontal in position and, secondly, said person being at least partly upright sitting or standing.

[0017] According to an embodiment, the detection unit is configured as an implant to be mounted, permanently or non-permanently, in a human skull.

[0018] According to an embodiment, the motion sensor comprises an accelerometer or a gyro unit, or a combination of an accelerometer and a gyro unit.

[0019] According to an embodiment, the detection unit comprises a housing defining an internal space which is configured for accommodating said further sensor device and an electronic control unit to which said sensor device is connected; and fastening means cooperating with said housing for mounting, optionally in a permanent manner, said arrangement in a human skull bone.

[0020] According to an embodiment, said further sensor device is a sensor device for measuring the intracranial pressure in a human skull.

[0021] According to an embodiment, the housing is arranged with an opening which is covered by a membrane being made of titanium or a similar thin and flexible material, and is configured for generating vibrations in accordance with an existing outer pressure, said vibrations being transferred to said sensor device.

[0022] According to an embodiment, the housing and opening are formed with a generally circular cross-section, and said membrane has a circular shape which corresponds to said opening.

[0023] According to an embodiment, the membrane has a thickness which is less than in the magnitude of 100 pm. According to an embodiment, the membrane has a thickness which is within the interval of 5-50 pm.

[0024] According to an embodiment, the further sensor device is constituted by a sensor device for measuring a cerebrospinal flow.

[0025] According to an embodiment, it comprises an electric accumulator which is arranged within said internal space.

[0026] According to an embodiment, it comprises a charging arrangement which is configured for inductive charging of said electric accumulator.

[0027] According to an embodiment, it comprises a charging arrangement which is based on an arrangement for energy harvesting.

[0028] According to an embodiment, it comprises an electric accumulator which is based on a capacitor.

[0029] According to an embodiment, the housing is manufactured by titanium.

[0030] According to an embodiment, the sensor device is mounted on a circuit board which is configured so as to divide the internal space into a first partial space between said circuit board and said membrane, and a second partial space between said circuit board and an end portion of said housing.

[0031] Furthermore, and in accordance with this disclosure, there is also provided a method for detecting the position or orientation of a person or a part of the body of said person by means of a detection unit comprising at least a sensor device based on a motion sensor for detecting said position or orientation. The method comprises the following steps: providing at least one further sensor device for a further physical parameter operating in association with the detection unit; configuring the detection unit with measured values (Ap) provided by said further sensor device based on a vertical height difference between the vertical position of the detection unit and the vertical position of the heart of said person; and using said measured values (Ap) as compensation during measurements with said further sensor device.

[0032] Furthermore, and in accordance with this disclosure, there is also provided a method for calibrating a detection unit for detection of the position or orientation of a person or a body part of said person, said detection unit comprising at least a sensor device based on a motion sensor for detecting said position or orientation. The method comprises the following steps: 1) registering the position and movement of said person or body part in relation to the force of gravity by means of the motion sensor in a flat vertical position; 2) detecting a reference value by means of a further sensor device for a further physical parameter when the detection unit is arranged in generally the same vertical plane as the heart of the person; 3) registering a change in position by means of said motion sensor when said person changes the position so that the detection unit is situated in a vertical position above the heart; and 4) using measurements relating to said changes in position to correct the measured further physical parameter values from the further sensor device.

[0033] Further advantages and advantageous features of the embodiments contemplated herein are disclosed in the following description and in the dependent claims.

[0034] In the present disclosure, the terms “patient”, “person” and “user” are used generally as synonyms.

[0035] Also, the term “vertical position” relates to a position of an object along a generally vertical axis or plane, i.e. the altitude or height of the object.

[0036] BRIEF DESCRIPTION OF THE FIGURES

[0037] The disclosure will be described in greater detail below with reference to the figures shown in the appended drawings.

[0038] Figure 1 shows a cross-sectional view of a part of a human brain, in which a detection unit according to a first embodiment of the invention is mounted;

[0039] Figure 2 shows a side view of the detection unit according to said first embodiment; Figure 3 shows a perspective view of the detection unit as shown in Figure 1 and Figure 2;

[0040] Figure 4 shows a cross-sectional view of the detection unit according to an embodiment;

[0041] Figure 5 shows a perspective view of the detection unit according to Figure 4; and

[0042] Figure 6a and 6b illustrate a calibration method in which the detection unit according to the above is used.

[0043] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0044] Different aspects of the present disclosure will be described more fully hereinafter with reference to the enclosed drawings and certain embodiments. The disclosure can be realized in many different forms and should not be construed as being limited to the embodiments below.

[0045] With initial reference to Figure 1 , there is shown a cross-sectional view of a section of a human skull 1 , in which a detection unit 2 according to an embodiment of the invention is mounted. A primary purpose of the detection unit 2 is to detect the position or orientation, or both, of the skull 1 and optionally also other parts of the body in question.

[0046] In Figure 1 , certain parts of the skull 1 are shown, such as the skull bone 3, the actual brain 4 with its cerebral cortex, and the dura mater 5, i.e. a hard membrane enclosing the brain 4.

[0047] The detection unit 2 is configured for being mounted in the skull bone 3 in either a permanent or non-permanent manner. Suitably, it is configured as an implant which is mounted by first making a hole 6 in the skull bone 3 in a manner so that the inner dimensions of the hole 6 generally correspond to the outer dimensions of the detection unit 2. As will be described in greater detail below, the detection unit 2 is configured with a lower end portion 2a which faces towards the brain 4 and also an upper end portion 2b which is formed as a flange, or rim, having a number of holes which are associated with a corresponding number of screws 7 or similar fastening elements. In this manner, a fastening arrangement for mounting the detection unit 2 in its intended position as shown in Figure 1 is defined. More precisely, the detection unit 2 can be mounted (in a generally permanent manner, if desired) in the skull bone 3.

[0048] Figure 2 shows in greater detail certain essential components of the detection unit 2 shown in Figure 1. According to an embodiment, the detection unit 2 comprises a sensor device 8 for providing information regarding changes in orientation or position of the user's head, in a three-dimensional space, assuming that the detection unit 2 is implanted in the head of the user, i.e. which is normally a patient. The sensor device 8 is based on a motion sensor unit, which is a sensor type which is previously known as such and which senses acceleration, rotational motion and changes in orientation, as described initially in this disclosure.

[0049] More specifically, the sensor device 8 may comprise an accelerometer, which is a sensor type which is configured for measuring linear acceleration along one or more axes, or a gyro sensor (alternatively referred to as a gyro unit, or gyroscope) which is configured for measuring angular velocity, or a combination of a gyro sensor and an accelerometer.

[0050] The gyro sensor 8 is mounted on a substrate 9 which also supports a central processing unit 10, an AC / DC converter 11 and an A / D converter 12. This is shown more clearly in Figure 3, which is a perspective view of the components shown in Figure 2. The purpose of the sensor device 8 and the additional components 9, 10, 11, 12 is to provide continuous measurements and data regarding movement, position and orientation of the skull 1 shown in Figure 1. Such measurements can also be used in cooperation with other measurements of other parameters related to the skull 1, as will be described in greater detail below.

[0051] The substrate 9 and the above-mentioned components 10, 11, 12 are mounted on top of a further unit in the form of a control unit 13, which is suitably configured with one or more projecting pins 14. These pins 14 are arranged to be aligned with, and to cooperate with, corresponding holes 15 (see also Figure 3) in the power source 16a. In this manner, the control unit 13 and the substrate 9 can be mounted together with high precision.

[0052] The central processing unit 10 can be arranged to operate together with the control unit 13 in a suitable way, i.e. one of these units may be, or may comprise, a memory unit and the other may comprise other components such as a microprocessor, communication components and similar devices, or vice versa.

[0053] The embodiment involving the parts of the detection unit 2 which are shown in Figure 2 and 3 comprises a sensor device 8 which operates as a position or orientation sensor, and also a pressure sensor 16 (not visible in Figure 3), will be described in greater detail below. However, it should be noted that the detection unit 2 can be used independently from any pressure sensor 16. In fact, the detection unit 2 can also be used with other types of sensors for other physical parameters, such as for example a flow sensor. In particular, the detection unit 2 can be used for monitoring of cerebrospinal fluid flow with or without shunt treatment. Such a shunt treatment is previously known as such, and is not described in detail here.

[0054] In the field of medical science, there is a need for devices and methods for measuring the intracranial pressure p (also referred to as “ICP”) in the brain of a patient and for detecting pulsations of the brain. Such a need may arise as a consequence of certain types of neurological disorders and injury to the brain, such as for example hydrocephalus. This condition corresponds to an abnormally high buildup of fluid in cavities within the brain and can normally be treated by surgically inserting a drainage system for controlling the flow of fluid in the brain.

[0055] For this reason, it is previously known to provide a pressure monitoring system in order to detect and monitor such intracranial pressure. Such a system can be implanted in the head of a patient and can be used together with an above-mentioned drainage system during treatment of hydrocephalus.

[0056] In order to improve measurements and to achieve a higher accuracy, the present disclosure relates to a combined use of measurements from the above-mentioned detection unit 2 with the pressure sensor 16. Furthermore, this combined arrangement where the detection unit 2 is associated with the pressure sensor 16 is furthermore configured so as to be calibrated in a particular way in order to take into account a mode of operation in which the patient is standing upright, i.e. having the skull 1 positioned higher than the right atrium of the heart, which in this context serves as a reference point for pressure measurements. This calibration process will be described in greater detail below.

[0057] With reference to Figure 4 and Figure 5, the detection unit 2 is shown in a cross-sectional view and a perspective view, respectively. With reference to Figure 4, there is shown in further detail how the detection unit 2 is configured. According to an embodiment, the detection unit 2 is based on a generally cylindrically shaped housing 17 which suitably is manufactured from titanium. The housing 17 is hermetically sealed, which means that no leakage from the outside, for example due to liquid in the brain 4, will be allowed into the housing 17. The housing 17 has a wall thickness which suitably is of the magnitude of 100-2000 pm. Also, according to an aspect, the diameter of the housing 17 is suitably in the magnitude of 5-15 mm.

[0058] The housing 17 is connected to the upper end portion 2b of the detection unit 2, i.e. the above-mentioned flange which is formed by the upper end portion 2b and which is used for fastening the housing 17, and thereby also the entire detection unit 2, in its correct position as shown in Figure 1.

[0059] The lower end portion 2a is formed with a generally circular end wall 18 which is formed with a preferably circular opening 19 in which a membrane 20 is mounted so as to cover the opening 19. According to an embodiment, the membrane 20 is generally circular and made of a thin, flexible material. Suitably, the membrane 20 is made by titanium and has a diameter which suitably is within the interval 4-8 mm, which generally corresponds to the diameter of the opening 19.

[0060] The purpose of the membrane 20 is to be influenced by the intracranial pressure and pulsations in the brain 4 so that movement of the membrane 20, for example in the form of regular or irregular deflections or vibrations, due to a varying pressure within the brain 4, will be transmitted towards the pressure sensing device 16 which is located within the interior of the housing 17. In this manner, pressure measurements can be registered in an accurate manner by means of the pressure sensing device 16. According to an embodiment, the pressure sensing device 16 is mounted on an electric circuit, such as a printed circuit board 21 , which is situated on the opposite side of the pressure sensing device 16, i.e. on the side of the pressure sensing device 16 which is not facing towards the brain 4. Also, the circuit board 21 is configured so that it supports the control unit 13 to which the pressure sensing device 16 is electrically connected.

[0061] The electronic control unit 13 is programmed so as to control the measuring process relating to the intracranial pressure and to store and transmit measurement data supplied by the pressure sensing device 16. To this end, the electronic control unit 13 is based on a microprocessor unit which is associated with a memory unit (for storing measurement data), an input unit (for allowing input of measurement data) and an output unit (for transmitting measurement data to external components). The detailed implementation of the electronic control unit 13 is as such configured in accordance with generally known technology. For this reason, it is not described in greater detail here.

[0062] As shown in Figure 4 and Figure 5, the housing 17 defines, encloses and hermetically seals an internal cavity or space 22 which is divided into a lower internal space 22a and an upper internal space 22b. The lower internal space 15a and the upper internal space 15b are divided by means of the electric circuit board 13, which consequently has the function of a dividing, or separating, wall. This also means that the pressure sensing device 9 is positioned within the lower internal space 22a. Suitably, the lower internal space 22a and the upper internal space 22b are sealed from each other, i.e. not connected.

[0063] According to an embodiment, the lower internal space 22a is filled with a non- compressible medium, such as suitably air, oil or silicon (in the form of a gel). When electronic components (such as the pressure sensing device 16) are enclosed within a hermetically sealed enclosure, there may occur pressure differences at different levels above the sea level. This may cause the thin membrane 20 to be deformed, which may lead to unwanted zero drift and possibly also damage to the membrane 20 due to such air pressure differences. By filling the lower internal space 22a with a non-compressible medium, a compensation for such air pressure differences will be provided.

[0064] Furthermore, as also indicated in Figure 4 and Figure 5, the printed circuit board 21 is connected to a power source 23, which suitably is in the form of an electric accumulator such as a chargeable battery, in order to supply electric power to the various components which are arranged on the printed circuit board 21, i.e. the electronic control unit 13 and its associated components. As shown in Figure 4, the power source 23 is positioned in the upper internal space 22b, i.e. on the same side of the circuit board 21 as the electronic control unit 13.

[0065] The power source 23 can furthermore be connected to a charging arrangement 24 which suitably is arranged within the upper internal space 22b. According to an embodiment, the charging arrangement 24 is of the energy harvesting type. Alternatively, the charging arrangement 24 can be based on a capacitor circuit with an inductive coil which is configured for inductive charging, i.e. wireless charging, via an external charging unit (not shown in the drawings).

[0066] The housing 17 is also connected to the lower end portion 2a of the detection unit 2 and is configured for accommodating the pressure sensing device 16 within its interior. The pressure sensing device 16 is arranged so that it faces (during operation of the detection unit 2) towards the brain 4 in order to measure the intracranial pressure therein, in a manner which will be described in more detail below.

[0067] The detection unit 2 according to this disclosure is suitably configured for detecting and measuring values relating to the position or orientation of a person in which the detection unit 2 is implanted. For this reason, the detection unit 2 comprises the above-mentioned motion sensor 8. Furthermore, and in order to obtain more accurate monitoring process, the detection unit 2 is configured for a calibration, or compensation, process, which is based on the use of the detection unit 2 together with a further sensor device. According to an embodiment, such a further sensor device is constituted by the above-mentioned pressure sensor 16. In this manner, the calibration (compensation) process uses the pressure measurement which is provided by means of the pressure sensor 16. This calibration is based on the insight that a correction of pressure measurements should be made as a result of the fact that the skull is situated higher than the right atrium of the heart, when the patient is in an upright position. In other words, due to the fact that the heart generates both the pressure of the blood and also in the brain, the right atrium of the heart will serve as a reference point against which the measured pressure (in the brain) should be calibrated. A process for calibrating the detection unit 2 based on the above principles will now be described with reference to Figure 6a and 6b, which show a user 25 (i.e. a patient) in which the detection unit 2 should be used. A first step is when the detection unit 2 is implanted into the patient's 25 skull 1 , as described above. The position and movement of the skull 1 can be registered in relation to the force of gravity by means of the gyro sensor 8 within the detection unit 2. More precisely, the detection unit 2 is implanted into the skull 1 in a manner so that the detection unit 2 and the right atrium of the heart 26 are situated at the same vertical level when the patient is lying flat (supine). As a second step, the pressure sensor 16 detects a “zero pressure value”, or “reference pressure value”, when the detection unit 2 is arranged in the same vertical plane as the heart 26.

[0068] A third step of the calibration process occurs when the patient 25 changes the position so that the skull 1 is situated above the heart 26, such as when the patient 25 is sitting generally upright or is standing (see Figure 6b). In this step, the motion sensor 8 will register this change of position in relation to the first step, i.e. when the patient was lying down and the detection unit 2 was implanted. This measurement is used, in a fourth step of the calibration process, to store the measurement data in the detection unit 2 for further transfer of information (which can be wireless) and also to correct the measured values of the pressure p from the pressure sensor 16, so that the difference in height, i.e. the vertical distance between the detection unit 2 and the heart 26, is converted into a pressure difference value Ap. This pressure difference value Ap is calculated based on an assumption that the vertical height difference (suitably measured in millimeters of water) between the position of the detection unit 2 and the position of the right atrium of the heart 26 corresponds to a pressure difference which is caused by the height difference and the force of gravity.

[0069] By using the process as described above, pressure measurements from the pressure sensor 16 will be more accurate and closer to the real pressure due to the fact that a compensation for the height difference between the detection unit 2 and the right atrium of the heart 26 is taken into account. In a normal situation, the height difference corresponds to a pressure of approximately 200 mm of water, which otherwise would be a source for errors in the pressure measurements.

[0070] Also, due to the fact that the heart generates both the blood pressure of the patient 25, and the pressure in the liquid in the brain of the patient 25, the right atrium of the heart 26 consequently constitutes a reference point (in the vertical direction) which is used when making corrections of the measured pressure p as provided by the pressure sensor 16.

[0071] It should be added that the measurements of the position and movement of the skull 1 by means of the detection unit 2 (i.e. the first step as explained above) can be used also for correcting and compensating for measurements of other physical parameters, for example as measured by a flow sensor. The concept for measuring and calibrating according to this disclosure is consequently not limited to pressure sensors.

[0072] The central processing unit 10 can be arranged to operate together with the control unit 13 in a suitable way, i.e. one of these units may be, or may comprise, a memory unit and the other may comprise other components such as a microprocessor, communication components and similar devices, or vice versa.

[0073] The control unit 13 and the power source 23 as shown in Figure 4 and Figure 5 are suitably generally circular and generally correspond to the interior dimensions of the housing 17. The motion sensor device 8 may comprise an accelerometer, or a gyro unit, or both an accelerometer and a gyro unit, and is used in order to provide information regarding the position of the user's head, in a three-dimensional space, when the detection unit 2 is implanted into the patient's 25 head.

[0074] According to a first embodiment, the detection unit 2 comprises a motion sensor in the form of an accelerometer 8. Such an embodiment is particularly useful for measurements in which the patient 25 is mobile, causing the head to change position in relation to the zeroing level set at the time of implantation, or when re-zeroing at a later occasion.

[0075] According to a further embodiment, the detection unit 2 comprises a motion sensor in the form of a gyro unit 8. Such an embodiment is particularly useful for measurements in which the orientation of the patient's 25 head is recorded in three dimensions in relation to gravity.

[0076] According to a further embodiment, the detection unit 2 comprises a motion sensor in the form of a combined accelerometer and gyro unit 8. Such an embodiment is particularly useful for measurements in which the patent 25 is mobile to register movements of the head in relation to the zeroing level and the orientation of the head in relation to gravity. According to an embodiment, which is not shown in the drawings, a portion of the upper end portion 2b is open, i.e. in order to allow radio transmission in and out of the housing 17. The opening is preferably sealed by means of a ceramic material, alternatively epoxy or silicon, in order to simplify the transmission of radio signals to and from the sensor arrangement while still sealing the housing 17. This is also implemented in order to allow inductive charging of the accumulator 23 as shown for example in Figure 4.

[0077] In summary, and as shown in Figures 1-6, the disclosure relates to a detection unit 2 for detection of the position or orientation of a person 25 or a part of the body of said person 25. The detection unit 2 comprises at least a sensor device 8 which is based on a motion sensor 8, for detecting said position or orientation. In particular, the detection unit 2 is associated with at least one further sensor device 16 for a further physical parameter. Also, the detection unit 2 is configured with measured values (Ap) which are provided by said further sensor device 16 based on (i.e. resulting from) a vertical height difference between the vertical position of the detection unit 2 (suitably when the detection unit 2 is in use) and the vertical position of the heart 26 of said person 25. Also, the detection unit 2 is configured for using said measured values (Ap) as compensation during measurements with the further sensor device 16.

[0078] Consequently, in an embodiment in which the detection unit 2 is used for providing pressure measurements by means of a further sensor device 16 in the form of a pressure sensor 16, the actual pressure measurements will be improved and more accurate, since a compensation for the fact that the person's 25 skull 1 (in which the detection unit 2 is mounted) is situated at another vertical position than the heart 25 will be provided.

[0079] The detection unit 2 is particularly suitable for being associated with a pressure sensor device 16 for detecting an intracranial pressure and comprises a housing 17 defining an internal space which is configured for accommodating the pressure sensor device 16 and an electronic control unit 13 to which said pressure sensor device 16 is connected. The detection unit 2 also comprises fastening means (i.e. the screws 7 being associated with corresponding holes in the flange 2b) which cooperate with said housing 17 for mounting said unit 2, optionally permanently, in a human skull bone 3. According to an embodiment, the motion sensor 8 comprises an accelerometer or a gyro unit, or a combination of an accelerometer and a gyro unit, for detecting the above- mentioned position or orientation of a person.

[0080] According to an embodiment, the detection unit 2 is configured for providing measured values based on measurements with the further sensor device 16, including a compensation (i.e. in the form of a correction, or adjustment) which originates from a process of registering a change in position of said person 25. More precisely, and according to an embodiment, measured values are provided and stored by registering a change in position of said person 25 (by means of the motion sensor 8) in relation to a reference position of said person in which the detection unit 2 and the right atrium of the person’s heart 26 are arranged in the same vertical plane. Such measured values are provided based on a vertical height difference between the vertical position of the detection unit 2 during use thereof and the vertical position of the right atrium of the heart 26 of said person 25. Also, the detection unit 2 is configured for providing measured values and said compensation during measurements with the further sensor device 16.

[0081] According to an embodiment, a difference in height (i.e. the vertical distance) between the detection unit 2 and the right atrium of the person’s heart 26 can be converted into a difference value. In case the further sensor device 16 is a pressure sensor, this difference value can be calculated as a certain amount (denoted with the unit millimetres of mercury) for each centimetre of height difference as detected by the motion sensor 8. The difference value is then added to the actual measurement of the pressure sensor. This means that a pressure difference value (Ap) is calculated based on the vertical height difference between the detection unit 2 and the right atrium of the heart 26, and also the force of gravity. Due to this, the invention results in more accurate measurements with the second sensor than with known arrangements.

[0082] Furthermore, the detection unit 2 is not limited to embodiments in which it is intended to be mounted in a human skull. It should be noted that the detection unit is based on inertial measurements in order to provide information relating to the position and orientation of a person. According to certain embodiments, such detection units can be in the form of, for example, wearable units which are based on inertial measurement units which acquire data from accelerometers and gyro units. Consequently, the detection unit 2 is configured for measurements using a motion sensor 8 but is not limited to being mounted as an implant in a human skull.

[0083] Furthermore, the detection unit 2 is associated with a further sensor device which can be a pressure sensor or another type of sensor for other physical parameters, such as for example a flow sensor, but is not limited to such sensors only. A certain embodiment relates to a sensor for measuring an intracranial pressure, and a further embodiment relates to a flow sensor. Such a flow sensor can, for example, be used for detection of a cerebrospinal flow. Generally, the detection unit can be associated with a second sensor for detection of other physical parameters than a pressure or flow parameter.

[0084] Furthermore, the housing 17 s arranged with an opening 19 which is covered by a membrane 20 being made of titanium and configured for generating vibrations in accordance with an existing outer pressure, said vibrations being transferred to said pressure sensor device 16. Furthermore, the pressure sensing device 16 is mounted on the underside of the circuit board 21 , which leads to certain advantages.

[0085] It should be mentioned that the pressure sensor device 16 provides very accurate and precise measurements without any substantial risk for zero drift. As shown in the embodiment in Figures 2-4, the housing 17 is suitably tapered along a section of the housing 17 which ends with the opening 19 and the membrane 20.

[0086] As indicated in for example Figure 4, the housing 17 and opening 19 are formed with a generally circular cross-section, whereas said membrane 20 has a circular shape which corresponds to said opening 19. Also, the membrane 20 has a thickness which is less than in the magnitude of 100 pm. According to an embodiment, the membrane 20 has a thickness which is within the interval of 5-50 pm.

[0087] The actual measurements and geometry of the detection unit 2, i.e. as regards for example the dimensions of the housing 17, the fastening means 7, the pressure sensing device 16 and the membrane 20, may vary depending on the requirements for measurements and the medical conditions in question. According to an exemplary embodiment, the housing 17 may have a diameter of approximately 5-15 mm, and the membrane 20 may have a diameter of approximately 4-8 mm. However, the invention is not limited to these specific dimensions. Furthermore, as shown in Figure 4, the sensor arrangement 2 comprises an electric accumulator 23 which is arranged within said internal space 22, and also a charging arrangement 24 which can be configured for example for inductive charging of said electric accumulator 23, or as an arrangement for energy harvesting.

[0088] Furthermore, the circuit board 21 is configured so as to divide the internal space 22 into a first partial space 22a between the circuit board 21 and the membrane 20, and a second partial space 22b between the circuit board 21 and an upper end portion 2b of the housing 17 of the detection unit 2. According to an embodiment, the first partial space 22a is filled with a non-compressible medium such as for example at least one of air, oil or gel / silicon.

[0089] Also, the electronic control unit 13 is configured for calibrating the measurements of the pressure sensor device 16 based on an existing atmospheric pressure, which contributes to accurate measurement data.

[0090] The invention is not limited to the embodiments described above but can be varied within the scope of the appended claims. It should also be noted that the principles of this disclosure are applicable to both humans and animals.

Claims

CLAIMS1. A detection unit (2) for detection of the position or orientation of a person (25) or a part (1) of the body of said person (25), said detection unit (2) comprising at least a sensor device (8) based on a motion sensor (8) for detecting said position or orientation; characterized in that: the detection unit (2) is associated with at least one further sensor device (16) for a further physical parameter (p); that the detection unit (2) is configured with measured values (Ap) provided by said further sensor device (16) based on a vertical height difference between the vertical position of the detection unit (2) during use and the vertical position of the heart (26) of said person (25); and that the detection unit (2) is configured for providing said measured values (Ap) as compensation during measurements with said further sensor device (16).

2. A detection (2) according to claim 1, wherein said measured values (Ap) are based on measurements of said further physical parameter with the person (25) first being generally horizontal in position and, secondly, said person (25) being at least partly upright sitting or standing.

3. A detection unit (2) according to claim 1 or 2, wherein said detection unit (2) is configured as an implant to be mounted, permanently or non-permanently, in a human skull (1).

4. A detection unit (2) according to any one of claims 1-3, wherein said motion sensor (8) comprises an accelerometer or a gyro unit, or a combination of an accelerometer and a gyro unit.

5. A detection unit (2) according to any one of the preceding claims, wherein the unit (2) further comprises: a housing (17) defining an internal space (22a; 22b) which is configured for accommodating said further sensor device (16) and an electronic control unit (13) to which said sensor device (16) is connected; and fastening means (7; 2b) cooperating with said housing (17) for mounting, optionally in a permanent manner, said arrangement (2) in a human skull bone (3).

6. A detection unit (2) according to any one of the preceding claims, wherein said further sensor device (16) is a sensor device for measuring the intracranial pressure in a human skull (1).

7. A detection unit (2) according to claim 6, wherein the housing (17) is arranged with an opening (19) which is covered by a membrane (20) being made of titanium or a similar thin and flexible material, and is configured for generating vibrations in accordance with an existing outer pressure, said vibrations being transferred to said sensor device (16).

8. A detection unit (2) according to claim 7, wherein said housing (17) and opening (19) are formed with a generally circular cross-section, and that said membrane (20) has a circular shape which corresponds to said opening (19).

9. A detection unit (2) according to claim 7 or 8, wherein said membrane (20) has a thickness which is less than in the magnitude of 100 pm.

10. A detection unit (2) according to claim 9, wherein said membrane (12) has a thickness which is within the interval of 5-50 pm.

11. A detection unit (2) according to any one of claims 1-4, wherein said further sensor device (16) is constituted by a sensor device for measuring a cerebrospinal flow.

12. A detection unit (2) according to any one of claims 4-10, further comprising an electric accumulator (23) arranged within said internal space (22).

13. A detection unit (2) according to claim 12, further comprising a charging arrangement (24) which is configured for inductive charging of said electric accumulator (23).

14. A detection unit (2) according to any one of claims 5-13, further comprising a charging arrangement (24) based on an arrangement for energy harvesting.

15. A detection unit (2) according to any one of claims 12-14, wherein said electric accumulator (23) is based on a capacitor.

16. A detection unit (2) according to any one of the preceding claims, wherein said housing (17) is manufactured by titanium.

17. A detection unit (2) according to any one of claims 5-16, wherein said sensor device (16) is mounted on a circuit board (14) which is configured so as to divide the internal space (22a; 22b) into a first partial space (22a) between said circuit board (21) and said membrane (20), and a second partial space (22b) between said circuit board (21) and an end portion (2b) of said housing (17).

18. A detection unit (2) according to claim 16, wherein said sensor device (16) is mounted on said circuit board (14) on a side which faces said membrane (20).

19. A detection unit (2) according to any one of the preceding claims, wherein said control unit (13) is configured for calibrating the measurements of said sensor device (16) based on an existing atmospheric pressure.

20. A detection unit (2) according to any one of the preceding claims, wherein said measured values are provided by registering a change in position of said person (25) in relation to a reference position of said person in which the detection unit (2) and the right atrium of the person’s heart (26) are arranged in the same vertical plane, and are based on a vertical height difference between the vertical position of the detection unit (2) during use thereof and the vertical position of the right atrium of the heart (26) of said person (25).

21. A method for detecting the position or orientation of a person (25) or a part (1) of the body of said person (25) by means of a detection unit (2) comprising at least a sensor device (8) based on a motion sensor (8) for detecting said position or orientation; characterized in that said method comprises the following steps: providing at least one further sensor device (16) for a further physical parameter (p) operating in association with the detection unit (2); configuring the detection unit (2) with measured values (Ap) provided by said further sensor device (16) based on a vertical height difference between the vertical position of the detection unit (2) and the vertical position of the heart (26) of said person (25); andusing said measured values (Ap) as compensation during measurements with said further sensor device (16).

22. A method for calibrating a detection unit (2) for detection of the position or orientation of a person (25) or a body part (1) of said person (25), said detection unit (2) comprising at least a sensor device (8) based on a motion sensor (8) for detecting said position or orientation; characterized in that the method comprises the following steps:1) registering the position and movement of said person (25) or body part (1) in relation to the force of gravity by means of the motion sensor (8) in a flat vertical position;2) detecting a reference value by means of a further sensor device (16) for a further physical parameter when the detection unit (2) is arranged in generally the same vertical plane as the heart (26) of the person (25);3) registering a change in position by means of said motion sensor (8) when said person (25) changes the position so that the detection unit (2) is situated in a vertical position above the heart (26); and4) using measurements relating to said changes in position to correct the measured further physical parameter values from the further sensor device (16).

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