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    • 专利摘要:
    Device for the determination of nail consistency. Device for obtaining measurements to determine the consistency of a nail plate of a nail of a user "in vivo". The nail plate comprises a free edge and is associated with a nail bed, characterized in that the device comprises a pressure mechanism adapted to apply a punctual force on the free edge of the nail plate and measure a force value that causes the bending of the free edge of the nail plate and optical pickup means configured to pick up the curvature of the nail before applying point force on the free edge of the nail plate, measuring the thickness of the nail sheet, and picking up the change in color of the nail bed caused by the bending of the free edge of the nail plate. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2784799A1
    申请号:ES201930273
    申请日:2019-03-26
    公开日:2020-09-30
    发明作者:Acevedo Raquel Mayordomo；Alvarez Ester Mingorance；Pico Ana María Pérez；Balsera Inés Tejado；Becerra José Emilio Traver；Jara Blas Manuel Vinagre；Arranz Javier Prieto；Bettle Vicente Feliu
    申请人:Universidad de Castilla La Mancha；Universidad de Extremadura；
    IPC主号:
    专利说明:

    [0002] Device for the determination of nail consistency
    [0004] Device for obtaining measurements to determine nail consistency.
    [0006] Object of the invention
    [0008] The present invention belongs to the field of study and diagnostic equipment used in the field of podiatry.
    [0010] The object of the present invention is to provide a device for obtaining objective measurements of the characteristics of the nail plate of "in vivo" users, as well as the mathematical method of evaluating them, to determine nail consistency. They are: the flexion of the free edge of the nail plate, the thickness of the nail plate, the curvature of the nail, the compression of the finger and the discoloration of the nail bed.
    [0012] Background of the invention
    [0014] The nail plate, commonly known as the nail, is the translucent part of the nail apparatus. It is composed of a hard keratin nail bed, flat in the longitudinal direction, convex at its edges and slightly curved at its end. Protects the structures of the finger (distal phalanges, sensitive structures and soft tissues) from abnormal pressures. It also participates in digital biomechanics by forming a hard layer, as if it were a shield, over the adipose tissue of the ball of the finger and the distal phalanx. In this way, when we take a step and put our fingers on the ground, the soft tissues tend to move upwards due to the reaction force of the ground and, when meeting the resistance of the nail plate, the contact surface increases, due to so the distribution of pressures on the ball of the finger is more balanced.
    [0016] Many systemic diseases, such as hypothyroidism, hyperthyroidism, connective tissue disorders, bronchopulmonary and cardiovascular diseases, psoriasis, kidney disorders, etc. they can produce alterations of the characteristics of the nails. Therefore, there are many factors that can cause nail alterations, which can be classified into injuries of traumatic and non-traumatic origin. Also, around the 10% of the population suffers from pathologies due to fungal infections, which represent 50% of the pathologies that affect the nails. Sports practice can increase the appearance of alterations such as laminar fracture, splintered hemorrhages, onychocryptosis or even the loss of the nail. These injuries not only affect the physical level, but also affect the emotional and social level of the people who suffer them.
    [0018] Onychomycosis is the infection of the nails by pathogenic fungi. It is one of the most frequent pathologies in the population and produces changes in the color and weakness of the nails as they are degraded by the pathogen. Treatment usually consists of antifungals. For its part, onychocryptosis is a painful pathology in which the lateral and / or distal edges of the nail penetrate into the periungual soft tissue. It is usually caused by mechanical microtrauma caused during daily activity and sports, and / or by the use of inappropriate footwear. Recent studies have established different nail consistencies in the population. In addition, they have highlighted the relationship between intrinsic factors (specific to each individual, such as sex, shape and consistency of the nails) and the appearance of onychocryptosis. However, there are no methodological tools in the literature that determine nail consistency in an objective, quantitative or reproducible way, and that allow the carrying out of research studies that analyze its relationship with other intrinsic and extrinsic factors.
    [0020] Thus, it is necessary to develop a tool to obtain measurements that determine the state and health of the nails. An affordable tool for health professionals, and especially podiatrists, that allows them to act at a preventive level, detecting variations in the characteristics of the nail plate of each individual. It would also be useful for more comprehensive examinations and for objective diagnosis and follow-up of prescribed treatments.
    [0022] Description of the invention
    [0024] In general, the maxim of health professionals is to instill primary prevention. At this level, in the podiatric setting, the device of the present invention will be able to perform initial measurements that determine the patient's own nail consistency in the absence of alterations. At the secondary prevention level, it will allow the early detection of alterations, by quantifying morphological or consistency changes that deviate from the baseline for the health status of each individual. In this sense, preventive actions may be established before the typical symptoms of the disease appear. systemic disease or nail disorder. In other cases, the device may be used to monitor the evolution of the prescribed treatment.
    [0026] A concrete example is its application in the treatment of onychocryptosis, which consists of correcting the morphology of the nail by restoring its correct development and / or shape. The first level of action and, depending on the severity of the case, consists of the reeducation of the nail plate using non-invasive methods (orthonyxias). The objective is to correct the growth of the nail plate from its origin in the nail matrix. The present invention will facilitate decision-making when establishing the most appropriate reeducation technique for each individual, taking into account their own characteristics and nail consistency (brackets, buttons, fixation systems, etc.). In addition, it will allow to monitor the degree of nail correction throughout the treatment and will stop the progression of the alteration and its possible complications. This progression usually requires invasive measures, predictably surgery, with the economic cost that this entails.
    [0028] Nail reeducation techniques are non-invasive and, therefore, well considered by patients. However, being treatments that take time, patients show little adherence. The use of the present invention will reduce treatment time, as it will provide vital information for choosing the most appropriate technique for each patient. Furthermore, the objective monitoring of the progress made will motivate patients to continue with the treatment and will provide the professional with the necessary information to modify the technique used, if necessary.
    [0030] Nail consistency is the result of the relationship of different variables measured in the nail plate: the flexion of the free edge of the nail plate, the thickness of the nail plate, the curvature of the nail, compression of the finger and the change in color of the nail plate. nail bed.
    [0032] Measurement of the flexure of the free edge of the nail plate provides information on the ability of the plate to deform and regain its starting position. The flexibility of this sheet depends on its adaptability to the finger tissues and their vascularization. The thickness of the nail plate indicates the thickness of the keratinocytes that make it up and the pressure it can exert on the tissues of the fingers. The measurement of the curvature of the nail indicates its position on the finger and is related to the probability of suffering from onychocryptosis. Finger compression allows standardization of the measurement position on the device. The measurement of the discoloration that occurs in the nail bed when the nail presses on the finger tissues can be useful to assess the distal flow, since it allows calculating the capillary filling time. This measurement is done by applying pressure to the nail until the bed turns white. This paleness indicates the cessation of blood supply to the tissue. Once the pressure is stopped, the blood flushes the tissue again and the bed turns pink. Although the assessment of distal blood flow can be performed by applying pressure with the hand, the human eye does not interpret colors in the same way, so there may be differences in the appreciation of it between professionals. This measurement is of vital importance when evaluating patients at risk, especially in the case of diabetic foot. All measurements provided by the device in an objective, quantitative and reproducible way, avoid possible interpretative differences between professionals: doctors, nurses and podiatrists.
    [0034] Therefore, the measurements obtained with the device, according to the present invention, must be carried out in combination with the performance of an adequate examination, before and during the follow-up of any established treatment, whether conservative or surgical. In this way, a more effective diagnosis will be made, the most appropriate therapeutic action will be planned, and the efficacy of the prescribed treatment can be monitored objectively over time.
    [0036] Description of the drawings
    [0038] To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical embodiment thereof, a set of drawings is attached as an integral part of said description in which, For illustrative and non-limiting purposes, the following has been represented:
    [0040] Figures 1A, 1B and 1C show different views of an embodiment of a device for obtaining measurements for the determination of nail consistency according to the present invention and a toenail of a user "in vivo".
    [0041] Figure 2 shows a block diagram of the electronic control system of the device according to the present invention.
    [0042] Figures 3A and 3B show a fingernail comprehension test.
    [0043] Figure 4 shows a diagram of the deflection of the pressure mechanism corresponding to a load cell.
    [0044] Figures 5A to 5D show different tests for the characterization of a load cell.
    [0045] Figure 6 shows a flow chart of events of the operation of the device for obtaining measurements for the determination of nail consistency.
    [0046] Figure 7 shows a travel speed profile of a load cell.
    [0047] Figure 8 shows a state machine of the test protocol.
    [0048] Figure 9 shows a human machine interface (HMI).
    [0050] Preferred embodiment of the invention
    [0052] Figures 1A, 1B and 1C show different views of an embodiment of a device (100) for obtaining measurements for determining the consistency of a nail plate (120) of a nail of a user "in vivo" according to the present invention.
    [0054] The device (100) has the following mechanical elements: a stepper motor (106) as an actuator for generating the movement that will be transmitted by means of a belt (107a) to two gears (107b) that transform the angular movement into transversal by two endless screws (107c), which allow the movement of a pressure mechanism corresponding to a load cell (101) for the bending test. The bending test is based on applying a point force on the free edge of the nail plate (120) and measuring a force value that causes the bending of the free edge of the nail plate (120).
    [0056] In this embodiment, the device (100) comprises a chassis (104) made of polyacid lactic acid (PLA) for the support of the different electromechanical and optical elements that allow obtaining measurements for determining the consistency of the nail plate (120) of a nail of a user "in vivo".
    [0058] The chassis (104) comprises a length of 130 mm, 170 mm in width and 110 mm in height. The chassis (104) can comprise other dimensions as long as they allow the support and subjection of the different electromechanical elements.
    [0060] As can be seen in figure 1A, the chassis (104) is mainly composed of a central block (112) where the coupling of one or more measurement components is carried out depending on the type of tests to be carried out. The device (100) consists of an upper base (104a) and a lower base (104b) that are assembled on the sides of the device (100), some rods (111) that restrict the rotation of the central block (112) and a double transmission shaft that includes a belt (107a), gears (107b) and worm screws (107c). Furthermore, the upper base (104a) serves to support and hold the actuator, which is a stepper motor (106). The lower base (104b) serves as a platform to locate the user's finger and a resistive force sensor (FSR) (103).
    [0062] The chassis (104) comprises openings (114) to allow recording of the test process. The device (100) comprises an optical capture means that comprises a camera (102a), shown in Figure 1C, to measure the curvature of the nail and the thickness of the nail plate, as well as the recording of the test. Furthermore, the device (100) comprises a photodetector (102b), which is shown in Figure 1B, to capture the change in color in the nail bed associated with cutting off the blood supply and to record and identify the collapse of the nail bed. In another embodiment, the optical capture means only comprise the camera (102a), which carries out the functions of the photodetector (102b).
    [0064] To perform the flexural tests of the nail plate (120), the device (100) has a mechanism for moving the load cell (101) (or point force), located in the central block (112). Both the nail plate (120) and the loading device (101) are seen in Figure 1B. The movement mechanism consists of the belt and gear system (107a, 107b) that transmits the angular movement of the stepper motor (106) to the axis of the central block (112), transforming the rotation into a linear movement, the part being the central block (112) movable. The union between the central block (112) and the transmission shaft is achieved through a metric nut and an endless screw (107c). With this design it is possible to limit the movement of the load cell (101) only in the vertical axis and with a unidirectional movement, that is, from the stepper motor (106) to the load cell (101).
    [0066] The movement of the central block (112) is based on a double central transmission shaft, while the lateral rods (111) serve as guides and prevent any type of rotation. The main reason for using the aforementioned transmission system is to avoid a continuous action of the stepper motor (106) on the nail plate (120) to exert a constant or variable force (pressure). Through this configuration, it is possible to reduce the necessary torque and increase precision, with a transmission ratio between the gears (107b) of n = - and a transmission coefficient of angular to linear movement of r = - 2 ^ n . mm / (rad / s). However, you can define a security protocol and establish shutdown conditions to avoid causing any type of harm to the user due to an uncontrolled or unforeseen failure.
    [0068] The electrical and electromechanical design of the device (100) is closely linked to the mechanical design and the requested requirements. To guarantee the versatility of the device (100), the development of an embedded system adapted to the required needs has been chosen. The technical characteristics of the developed system are shown in Table 1.
    [0070]
    [0072] Table 1: General characteristics of the device (100).
    [0074] A conceptual diagram of the devices that make up the device (100) is shown in figure 2.
    [0076] The computing means comprise a control unit (105a), shown in Figures 1A, and 1C and 2, which in the present embodiment is a general purpose 8-bit microcontroller with a sufficiently high instruction frequency (for example , 4 MHz) that allows classifying the device (100) as a real time system. The control unit (105a) comprises different serial communication interfaces, such as the I2C and SPI interfaces, to communicate with other elements of the device (100), and a USB interface or connection port (109) and an Ethernet interface ( 110) for direct communication with a computer without the need to add signal adapters. The communication of the components described in figure 2 is carried out by means of the software programming of the chosen microcontroller.
    [0078] In said preferred embodiment, a prototyping board (108) is included that integrates the control unit (105a) and offers the possibility of quick programming and quick and easy access to the rest of the interfaces, such as the USB port (109) and an Ethernet interface (110).
    [0079] The mechanical means comprise the stepper motor (106) used to drive the load cell (101) shown in Figures 1 and 2. The stepper motor (106) functions as an electromechanical transducer that converts a digital pulse into a mechanical rotation. This motor (106) offers a great number of advantages, such as its simplicity since there is no friction due to the absence of brushing, its low cost, its high reliability, high torque at low speeds and its high precision of movement. A bipolar stepper motor has been chosen, characterized by energizing the complete winding and using a full bridge microcontroller, in addition to a limit switch (FC) sensor (122) to limit the movement of the motor. A complementary advantage to those mentioned is the ability to use the motor as a position sensor. The technical specifications of the stepper motor (106) are a torque of 48 N c / m and a resolution of 400 steps per revolution.
    [0081] Additionally, to correctly excite the windings of the stepper motor (106), a control electronics is included that comprises an integrated circuit (IC) included in the prototyping board (108), where the connector and the connection cables are also shown. (105b). With this step it is possible to control the direction of rotation or blocking of the stepper motor (106) through the control unit (105a). It will therefore be the control unit (105a) that determines its operating mode based on its programming. The electronics used comprise an IC and the necessary circuitry to ensure proper operation of the IC. The IC integrates two full H-bridges capable of handling the high voltages and currents required by the stepper motor (106). In addition, it incorporates a digital part in charge of simplifying the task of controlling and switching the H-bridges to a reduced number of digital signals. Additionally, it incorporates the functionality of “microstepping”, allowing to increase the resolution of movement up to 16 times.
    [0083] Figure 1B shows an image of the positioning of the nail plate and the load cell (101) on the test bench before starting the measurements. The photodetector (102b) can detect the discoloration of the nail bed produced in the nail plate (120) by a wavelength close to 525 nm. The photodetector (102b), according to the preferred embodiment, includes three LEDs, photodetectors, optical elements, and noise reduction electronics with ambient light rejection. The photodetector (102b) incorporates a green LED with a wavelength of 537 nm, and additionally, an infrared LED and a red LED with a wavelength of 880 nm and 660 nm, respectively. The photodetector (102b) incorporates an A / D converter (121) of 18 bits that avoids the addition of noise by the use of external converters. Communication with the control unit (105a) is implemented through a digital protocol, such as I2C, which makes it possible to increase immunity to noise. The control of the photodetector (102b) is carried out through the prototyping plate (108).
    [0085] The embodiment of Figures 1A, 1B and 1C comprises the load cell (101) adapted to apply a point force on the free edge of the nail plate (120). The embodiment of Figures 1A, 1B and 1C comprises a button or "cantilever" type load cell (101). In other embodiments, the pressure mechanism may comprise a spring. The "cantilever" type load cell (101) allows determine the force exerted in a more precise and simple way, as well as direct vision between the nail plate (120) and the photodetector (102b).
    [0087] To properly choose the load cell model (101) of the device (100), several compression tests were carried out with a false nail. The purpose of this series of tests was to determine the range of forces that can produce flexure of the user's nail by applying a force value to the nail plate (120). Although the material of the false nail does not correspond exactly to the composition of the nail plate (120), it is possible to treat it as an intermediate material that exhibits a behavior equivalent to a nail of medium consistency. Figures 3A and 3B show the results obtained for two tests with different speed profiles. Thus, from these tests, a range of compression forces to apply to the nail plate (120) of the order of ± 2.5 kgf can be extracted. For higher compression forces, the maximum deflection of the material has already been reached and the material begins to deform in conjunction with its support. Based on these tests, the load cell model (101) of the preferred embodiment of the figures admits a maximum force of 2.27 kgf, although it can withstand up to 3.5 kgf.
    [0089] The load cell (101) shown in Figures 1A, 1B and 1C is based on a stainless steel sheet on which a Wheatstone bridge is implemented, with the corresponding correction resistors. The mechanical properties of the sheet, in conjunction with instructions from the computing means, determine the force applied from the deflection produced in the nail plate (120). The stainless steel gives the load cell (101) a Young's modulus of 200 GPa. Considering an embedded beam as a homologous application supporting a point force on its free end, a theoretical displacement of 2.57 ^ m / gf is obtained.
    [0090] In order to record the drift produced in the Wheatstone bridge, the A / D converter (121) can be used. Specifically, the electronics used with the IC incorporates a 24-bit sigma-delta analog-digital converter. Communication with the IC is done through an SPI protocol. The implementation of this protocol implies a greater use of the control unit (105a) time, thus increasing the probability of being interrupted by higher priority actions, the result of which is a communication failure and the reading of erroneous values.
    [0092] The load cell (101), in a first instance, can be considered as an elastic spring with a stiffness to deformation greater than the study system. Some studies carried out to model the load cell (101) as a spring are described below.
    [0094] Before carrying out an empirical analysis of the elastic behavior of the load cell (101), it has been theoretically characterized considering its mode of use as an embedded beam on which a point load is applied. On the other hand, to facilitate the analysis, a uniform section of the load cell (101) has been taken as a reference, with the absence of perforations. According to this, the bending experienced by the load cell (101) is observed in figure 4 and can be determined from the following equation:
    [0096] S (t) = F (t) -1 - (L - d) 2 (2L d) bbl
    [0098] where F ( t) is the force exerted on the load cell (101), L is the length of the load cell (101) from its embedment, E is Young's modulus, I is the moment of inertia of the section and d is the distance between the point of application of the force and the end. From it, the inverse of the spring constant ( K) of the equivalent spring is calculated as:
    [0103] For d = 2mm, a theoretical value for this parameter of 2.5764 ^ m / gf is obtained.
    [0105] To validate the considered model and corroborate the result obtained, a set of sixteen tests grouped into four blocks of different displacement speeds was carried out. The tests consisted of subjecting the load cell (101) to a gradual force of up to 1 kgf and recording the deflection caused. This force was applied to a 2.5mm distance from the end. The results, referred to the inverse of the elastic constant K, are shown in Table 2.
    [0109] Table 2: Assays for the characterization of the load cell.
    [0111] The average value of the test set for the inverse of the elastic constant K is 2.5242 ^ m / gf, which differs by 2.0261% from that obtained theoretically, but which can be neglected taking into account the consideration made. Figures 5A to 5D represent the data obtained during the tests, in which a clear linear character is evidenced.
    [0113] Device (100) also comprises a chamber (102a), as seen in Figure 1C. The camera (102a) can measure the curvature of the nail prior to the bending test by means of the load cell (101) and the thickness of the nail plate (120). The camera can offer the function of following the process "in vivo" to control the assay.
    [0115] Additionally, device 100 comprises FSR 103, which may not be included in other embodiments of the invention. The FSR (103) can be used to obtain a measure of finger compression that can be used to modify, weight, correct, etc. the value of force measured with the load cell (101) causing the flexion of the free edge of the nail plate (120).
    [0117] The FSR (103) is a polymer film sensor that exhibits a decrease in resistance when the force applied to the active surface increases. The FSR (103) is at the base of the device, where the user's finger is placed. The FSR (103) can obtain a measure of the compression of the finger, during the deformation of the nail. The FSR (103) is a sensor with a limit of 5 kgf. Its output value is a voltage that can be read by the control unit (105a) of the device (100).
    [0118] The communication of the previously described components is carried out by means of the software programming of the control unit (105a). Thus, the main operation of the device (100) and the programmed methods to manage the resources of the device (100) are addressed. In addition, the measurements performed to calibrate and define the operating mode of the electromechanical components described are detailed.
    [0120] The programming implemented in this particular embodiment to manage the resources of the device (100) is developed under the concept of multitasking and performance by interruptions. A set of actions are executed sequentially but undertaken in different periods of time. Regarding the character of action due to interruptions, it is based on the execution of predefined instructions under certain conditions.
    [0122] The structure of the main program is outlined in figure 6, which comprises two main stages: initialization (601) and execution (602).
    [0124] The first initialization stage (601) configures the different hardware modules of the control unit (150a), the operating mode of the photodetector (102b) and the A / D converter (121) of the load cell (101). The initialization stage (601) comprises the step (601a) for the configuration and declaration of I / O interfaces, a stage (601b) for configuring the load cell, a stage (601c) for the configuration of the optical sensor and a step (601d) for the configuration of the arithmetic unit. The reception of a start control command in step (601e) allows to proceed to the execution step (602). The last action of step (601) consists in establishing and verifying the connection with the HMI interface. To ensure connection with the device control interface (100), the reception of the start control command must be verified in step (601e). In the event that this condition is not satisfied, the device (100) will be blocked, and manual movement of the load cell (101) will not be allowed as a safety measure.
    [0126] The execution stage (602) is structured in two central loops: execution (603a) and events (603b). The execution of the first (603a) is sequential and iterative. Within it, three sets of actions are distinguished according to their priority at frequencies of 100 Hz for the step (604a) for updating and filtering variables, frequencies of 50 Hz for the step (604b) for checking stop conditions and communication with the HMI interface and frequencies of 0.5 Hz for the step (604c) for emergency stop. The block of events (603b) is executed in a priority and asynchronous way, attending to the previously established requirements.
    [0127] The updating of the measurements from the load cell (101) and the photodetector (102b), as well as their corresponding filtering by means of a Kalman filter, are carried out within the 100 Hz loop. This ensures the ability to observe the dynamics of the system under study, without sampling problems. On the other hand, to avoid the loss of information during communication with the HMI control interface, the variables of interest can be accumulated in a memory buffer, allowing a reading delay of 320 ms. Furthermore, within the execution loop (603a) the actions corresponding to the 50 and 0.5 Hz loops must be executed, as a consequence of the pseudomultitasking nature of the programming.
    [0129] The 50 Hz loop focuses on verifying the assay stop condition and establishing communication with the control interface. The stop condition is activated when the maximum applicable force is reached. The last 0.5 Hz loop is responsible for checking the stop condition and stopping the test, removing the load cell (101).
    [0131] The force exerted by the load cell (101) can be indirectly controlled through its movement by position control of the stepping motor (106). The load cell (101), as detailed above, is moved by the main shaft, whose linear speed, and therefore position, is determined by the transmission system with the set of gears (107b, 107b) and the stepper motor (106). The angular speed of the stepper motor (106) is exclusively defined by an open loop controller, since, for the type of stepper motor (106) chosen, the angular speed (<¿> m) is determined by the time interval between excitation pulses ( St) and displacement resolution (number of pulses per revolution, spr ):
    [0136] The parameter spr is a characteristic intrinsic to the type of stepper motor (106) chosen. However, the driver used offers the “microstepping” functionality. This option allows you to expand the number of pulses required to make one revolution, thus increasing the precision of movement. In the configuration of this operating mode, the maximum possible resolution has been chosen: spr = 6400 (resolution of 6400 pulses per revolution).
    [0137] The implemented position control is based on a speed algorithm. Unlike other implementation methods, this algorithm allows reaching a position smoothly, incorporating a speed profile without instantaneous stops that require the use of electronics with high threshold values for current and peak voltages. In addition, the algorithm incorporates the parameterization and calculation in real time of the parameters: acceleration, velocity, position and deceleration. Additionally, the electronics used simplify the control task by dealing with the generation of the switching signals.
    [0139] The speed profile is defined as shown in Figure 7. The stepper motor (106) starts with zero speed and accelerates to the desired speed. Speed remains constant until deceleration. From that moment, the stepper motor (106) decelerates until it stops after the number of steps indicated. The characterization of the speed profile is based on determining the distance at which the maximum speed is reached according to the specified acceleration and when it must begin to decelerate to finish in the indicated position.
    [0141] Once the velocity profile is characterized, the excitation interval is calculated through a state machine.
    [0143] The transition between states occurs when the distance predefined by the speed profile is reached. Regarding the actions carried out in each state, these are reduced exclusively to two in order to reduce the computation time: the first, to define the period of time in which the next excitation should occur and the second, to check if a transition occurs of State.
    [0145] The implementation of the state machine is carried out by means of interruption actuation and with the help of the “speedRampData” data structure , which stores in memory the information corresponding to the transition conditions, the current state, the direction of rotation of the stepper motor. (106) and the time interval in which the next excitation signal should be generated. At the same time, said time interval is used to activate the interrupt in which the state machine runs. It is necessary to clarify that the kinematic variables have been scaled by a factor of 100, in order to optimize the processing time of the microcontroller. In this way, it is possible to avoid the use of floating point arithmetic and to maintain the same degree of precision.
    [0146] The expression that relates the angular speed of the stepper motor (106) and the displacement (x (t)) of the load cell (101) is:
    [0148] x ( t) = 3,927 • 10-6o) m (t) (m / s)
    [0150] Table 3 shows, for a set of four tests, the experimental speeds generated and the theoretical speed. In addition, the correction factor to be applied to know the real speed generated is indicated.
    [0152]
    [0154] Table 3: Speed check tests.
    [0156] From the results shown in the previous table, it is obtained that the theoretical speed corresponds to the speed generated by applying a correction factor of 2.177. Therefore, the above expression is rewritten as:
    [0158] x (t) = 2,177 ■ 3,927 • 10 ~ 6wm ( t) = 8,549 • 10 “6 ^ m (í) (m / s)
    [0160] Previously, the use of the A / D converter (121) has been described to determine the potential difference produced by the Wheatstone bridge incorporated in the load cell (101) and thus determine the force that is being applied at each instant of time. . The A / D converter (121) chosen allows configuring the gain of the preamplifier stage that it incorporates and the signal sampling rate, the latter configuration being determined by hardware.
    [0162] The gain of the chosen pre-amplification stage is the maximum possible, that is, 128. This allows increasing the resolution of the load cell (101) and the ratio signal / noise. The chosen sampling frequency of 80 Hz is the maximum allowed by the characteristics of the A / D converter (121) in order to record the largest possible spectrum. The reading of the A / D converter (121) is carried out through a simple programming, based solely on implementing the communication protocol and reading the value returned by the communication module of the A / D converter (121). On the other hand, during the initialization stage (601) the offset or error calibration is performed at zero load. This consists of calculating the deviation of the Wheatstone bridge for a zero load and compensating for the deviation in future measurements. In addition, the gf / bit conversion factor is established, which can be calculated empirically. The tests carried out to quantify said factor were based on subjecting the load cell (101) to a known force and recording the measured digital value (mean value), as shown in Table 4.
    [0164]
    [0166] Table 4: Load cell calibration tests.
    [0168] Based on the previous results, a conversion factor of 413.17 ^ gf / bit was determined.
    [0170] To guarantee the same starting and performance conditions for each trial and individual, and consequently to ensure the consistency of the measurements, a trial protocol has been established. The protocol is divided into three stages: start, action and end. The first stage is exclusively due to the user responsible for managing the device (100) and to the patient; instead, the last two are defined and configured via software.
    [0172] The purpose of the actuation step is to position the load cell (101) on the free edge of the nail plate (120). To achieve this purpose, a set of actions are performed sequentially, defined by the state machine shown in figure 8, which are based on: initialization of variables, approach to the nail plate (120) until its detection, control of force on the nail plate (120) of 10 gf and calibration of the photodetector (102b) according to the environmental conditions and the reflection characteristics of the nail plate (120).
    [0174] Once the above conditions have been established, the test is started until the maximum established force is reached. Once the maximum test force has been reached, the last stage begins, in which the load cell (101) moves back to the starting position, guaranteeing a comfortable and safe withdrawal of the finger, in addition to avoiding any type of unwanted collision with sensors.
    [0176] This protocol is intended to standardize the same initial conditions regardless of the morphology of the patient's finger.
    [0178] To facilitate the use of the device (100), an example of an HMI desktop application (1000) has been developed to offer the user a quick and easy way to perform tests and visualize the data. The HMI application (1000) avoids the need to resort to calculation programs or specific application, outside the field of knowledge of a basic user. Furthermore, to provide greater convenience to users, the HMI application (1000) is multiplatform, that is, it supports different operating systems.
    [0180] Figure 9 shows the main window of the HMI application (1000) for the device (100) named "Nail consistency meter" or "MCU", which is structured in four areas:
    [0182] - Tools (1010): It comprises the toolbar where the basic functions of the HMI application (1000) are found (for example, saving and opening files) and the configuration of special device parameters (100). Specifically, the tools area (1010) allows modifying the color detection threshold and the maximum force that will be applied during the tests.
    [0184] - Control commands (1020): Area of the interface that groups the main action commands of the device. It contains actions to detect and connect to the USB connection port (109) to which it will be connected, modify the speed of movement of the load cell (101) and control its movement, and restart the device (100) to its initial conditions. In addition, the commands control (1020) comprise a specific button "RUN" to start the tests. This button will appear as "STOP" during the operation of the device (100).
    [0186] - Device information (1030): Interface area that is composed of two indicators, "position" and "force", which provide information at all times on the position of the load cell (101) with respect to its initial position and the exerted force, respectively.
    [0188] - Representation of data during the test (1040): Area of the interface that shows a graphic representation in real time of the data (position with respect to force) obtained during the test. This same area can be used to represent data for other saved tests.
    [0190] Regarding programming, the HMI application (1000) can be carried out in a programming language, such as Python, implementing the reading and visualization of data through concurrent programming and the demand of user requests through interruptions.
    [0192] This document includes an example of a route guide for the use of the device (100). The steps they must follow to put the device (100) into operation and start testing will be explained. In addition, it is indicated, for example, how to save the recorded data or view the information obtained in other tests, whose data were previously saved.
    [0194] It starts with the connection of the device (100) to a personal computer (PC) through a USB - microUSB cable and USB connection port (109). The connection of the PC with the device (100) can be done with the following steps:
    [0196] 1. Identify the connection port to which the device (100) is connected.
    [0197] To do this, press the "Refresh" button (located in the Control command area (1020)).
    [0198] 2. The port to which it is connected is selected through the drop-down menu (1012). The menu (1012) is located just below the "Refresh" button in the control command area (1020).
    [0199] 3. The “Connect” button is pressed. If the connection is successful, the “Disconnect” button will appear. Otherwise, communication may not be established due to one of the following errors:
    [0200] a) The selected port does not correspond to that of the device (100). The solution would be given by trying other ports, or
    [0201] b) the cable is not well connected. The solution would be given by checking the connections.
    [0203] Once the device (100) is connected to the PC there are several options: Carry out a manual control on the load cell mechanism (101) or start the test. Manual control is performed by the controls in the control command area (1020). The position of the load cell (101) and the force exerted will be indicated at all times through the information area (1030) of the device (100). Regarding the second option, the start of the test is started by clicking on the “RUN” button in the control command area (1020). From that moment on, a set of automatic actions are carried out that lead to the start of the test. From the beginning of the test, both in the information area (1030) of the device (100) and in the data representation area (1040), the recorded data begins to be displayed. The test can be stopped at any time by pressing the "STOP" button.
    [0205] This will cause the immediate stop of the load cell (101) and its return to the starting position. To repeat a new test it is necessary to restart the device (100), otherwise it will not be possible to start. Therefore, once a test is finished, it is necessary to press the “Reset” button and then “RUN” in the control command area (1020).
    [0207] After the test, there is the option of saving the data in a .flx file . The save option is found in the “File” tab of the toolbar (1010). In the same tab there is also the option to open saved data.
    [0209] On the other hand, the maximum force and color detection threshold value parameters are modified with the “Settings” option on the toolbar (1010). It is necessary to indicate that these parameters are reset to their default values each time the HMI application (1000) is started.
    [0210] The HMI application (1000) can be closed at any time, although it is recommended that it be closed when communication with the device has ended, if it had been established.
    [0212] A test protocol has been established in order to guarantee, as far as possible, the same starting and performance conditions for each test and individual and, consequently, to ensure the consistency of the measurements. The protocol is divided into four stages: image capture, start, actuation and end.
    [0214] The image capture with the camera (102a) allows us to know the curvature of the nail and the thickness of the nail plate (120), prior to the performance of the test. The captured image will be subsequently processed, giving a curvature of the nail and a thickness of the nail plate (120). This photo will be taken when the "RUN" button of the control command area (1020) of the device (100) is pressed to perform the test, once the foot has been placed in the initial position.
    [0216] The initiation stage refers to the proper positioning of the nail plate (120) of the first toe of each individual on the test bench to standardize the same measurement conditions for the different tests and individuals. It is the most decisive phase to ensure the reproducibility of the data and, at the same time, the most difficult due to the human and mechanical factors involved. To this end, two principles are established. First, the operator of the device (100) must manually ensure the following conditions, according to the order indicated:
    [0218] 1. The nail plate (120) must not be inserted below the load cell (101) for a length greater than 3 mm from the start of the free edge. Otherwise, the correct determination of the cessation of blood supply in the nail bed would be prevented by the photodetector (102b). Optionally, the cessation of blood supply to the nail bed can be determined with camera 102a.
    [0219] 2. Once the nail plate (120) is positioned, the following set of actions is carried out automatically, already preconfigured in the device (100), which aim at adapting the meter to the morphology of the individual's finger:
    [0220] 2.1 Initialization of variables.
    [0221] 2.2 Approximation of the load cell (101) to the nail plate (120) until its detection.
    [0222] 2.3 Verification that a pressure of 10 gf is exerted on the nail plate.
    [0223] 2.4 Calibration of the photodetector (102b) according to the environmental conditions and the reflection characteristics of the nail plate (120).
    [0225] Once the above steps are completed, the acting stage takes place. Unlike the previous one, in this one only mechanical factors intervene. It is mainly defined by two parameters: the maximum application force and the actuation speed. The default values for the tests are 1000 gf and 518 ^ m / s (theoretical), respectively.
    [0227] Finally, the end stage, closely related to the previous stage, begins when the load cell (101) reaches the maximum indicated application force. From this moment on, the load cell (101) goes back to the rest or start position. In this way, a comfortable and safe withdrawal of the finger is guaranteed, preventing it from colliding with any sensor of the device (100).
    权利要求:
    Claims (9)
    [1]
    1. Device (100) for obtaining measurements to determine the consistency of a nail plate (120) of a nail of a user "in vivo", the nail plate comprises a free edge and is associated with a nail bed, characterized by comprising:
    a) a pressure mechanism (101) adapted to:
    - apply specific force on the free edge of the nail plate; Y
    - measure a force value that causes the bending of the free edge of the nail plate; Y
    b) optical capture means (102a, 102b) configured to:
    - capture the curvature of the nail before applying the point force on the free edge of the nail plate (120);
    - measure the thickness of the nail plate (120); Y
    - to capture a change in the color of the nail bed caused by the bending of the free edge of the nail plate (120).
    [2]
    The device (100) according to claim 1, comprising:
    a resistive force sensor (FSR) (103) configured to obtain a measure of finger compression.
    [3]
    The device (100) according to claims 1 and 2, wherein the pressure mechanism comprises a load cell (101).
    [4]
    4. The device (100) according to claims 1 to 3, wherein the optical pickup means comprise a camera (102a).
    [5]
    5. The device (100) according to claims 1 to 3, wherein the optical pickup means comprise:
    a camera (102a) configured to:
    - capture the curvature of the nail before applying specific force on the free edge of the nail plate;
    - measure the thickness of the nail plate (120); Y
    a photodetector (102b) configured to capture the discoloration of the nail bed caused by flexing of the free edge of the nail plate.
    [6]
    6. Method for obtaining measurements for determining the consistency of a nail plate (120) of a nail of a user "in vivo", where the nail plate (120) comprises a free edge and a nail bed. understands:
    - capturing the curvature of the nail by means of optical capturing means (102a, 102b);
    - measuring the thickness of the nail plate (120) by means of the optical capture means (102a);
    - applying a point force on the free edge of the nail plate (120) by means of a pressure mechanism (101);
    - measuring a force value that causes the bending of the free edge of the nail plate by means of the pressure mechanism (101);
    - capturing a color change of the nail bed associated with the bending of the free edge of the nail plate (120) by means of the optical capturing means (102b), and
    - estimate the consistency of the nail plate (120) based on the force value that causes the bending of the free edge of the nail plate (120), the thickness of the nail plate (120), the curvature of the nail and the change of staining of the nail bed.
    [7]
    7. The method according to claim 6, comprising:
    - obtaining a measurement of the finger compression by means of a resistive force sensor (FSR) (103);
    - weighting the force value that causes the bending of the free edge of the nail plate (120) with the measurement of the compression of the finger; Y
    - estimating the consistency of the nail plate (120) also based on the weighted force value.
    [8]
    The method according to claims 6 and 7, further comprising:
    - classify a user's nail type as hard or soft nails based on
    in the consistency of the nail plate.
    [9]
    9. The method according to claims 5 to 8, further comprising:
    - select a default shoe for the user based on the type
    user nail;
    - Follow-up of orthonixia treatments by monitoring the thickness of the nail plate (120) and curvature of the nail.
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    同族专利:
    公开号 | 公开日
    ES2784799B2|2021-04-16|
    ES2784799A8|2020-10-22|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP1512372A1|2003-09-05|2005-03-09|DERMING S.r.l.|Method and device for quantidying the extension of a colour-altered skin or nail area|
    US20150072434A1|2004-06-22|2015-03-12|Crescent Diagnostics Limited|Methods for assessing risk of bone fracture|
    GB2448546A|2007-04-20|2008-10-22|Crescent Diagnostics|Raman spectroscopy apparatus for analysing fingernail material|
    US9743906B2|2007-05-31|2017-08-29|University Of Windsor|Ultrasonic device for cosmetological human nail applications|
    CN105816177A|2016-01-07|2016-08-03|张石川|Nail growth detector and detection method|
    法律状态:
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