Multifunctional digital assessment intelligent seat
Technical Field
The invention belongs to the field of medical instruments, and particularly relates to a multifunctional digital evaluation intelligent seat.
Background
The assessment of the dyskinesia patients is mostly diagnosed and assessed by clinical medical staff through subjective experience, for example, the assessment and diagnosis method of the Parkinson disease patients comprises the following steps: according to assessment items and standards in a unified Parkinson disease assessment scale (UPDRS) published by the International dyskinesia Association (MDS), medical staff are obtained by experience observation and judgment, namely, indexes such as tremor degree, muscle rigidity degree and unbalance degree of bilateral limbs of Parkinson disease patients are observed and assessed through naked eyes so as to carry out subsequent diagnosis, subjective factors exist, and the tremor amplitude, the muscle rigidity and the unbalance degree cannot be accurately quantified, and the defects exist. The existing assessment device mainly performs tremor assessment through an acceleration sensor, but has the defects of inconvenient wearing and capability of only assessing a single symptom.
Disclosure of Invention
In order to solve the technical problems, the flexible piezoresistive sensors, the servo motor and the inertial sensor are arranged on the seat cushion and the armrest parts of the special seat, and partial symptoms of the dyskinesia disease are evaluated, including but not limited to measuring the tremor degree, the muscle stiffness degree, the limb discordance degree, the rising force condition and the like of a patient, so that the aim of objectively and accurately evaluating the illness state of the dyskinesia disease patient including the Parkinson patient is fulfilled, and the special seat has the advantages of reproducibility, storage and analysis. The invention installs flexible piezoresistance sensors on the seat cushion and the armrest part of the special seat, installs a motor encoder and an acceleration sensor on the armrest part, transmits pressure distribution change data of a contact surface above the sensors, motor rotation data and armrest part inertial sensor data to an upper computer through wired serial port protocol transmission, processes and analyzes the data by the upper computer to obtain relevant parameters of a collected patient, and stores the data and an analysis result.
The technical scheme of the invention is that the multifunctional digital evaluation intelligent seat comprises: the seat comprises a seat body, a base, a cushion part and an armrest part;
the intelligent seat is characterized in that flexible piezoresistive sensors are respectively arranged at the seat cushion part and the armrest part of the intelligent seat, and a servo motor encoder and an acceleration sensor are additionally arranged at the armrest part;
the flexible piezoresistive sensor is used for acquiring pressure distribution change data of a contact surface above the surface; the flexible piezoresistive sensor comprises: the conductive layer is provided with stainless steel conductive fibers and polyethylene fibers; the two conductive layers are vertically arranged at ninety degrees horizontally, and a flexible semiconductor piezoresistor layer is arranged between the two conductive layers and is formed by staggering silicon carbide fibers and polyethylene fibers; fixing the three layers of threads by using a sewing machine, and reinforcing by using hot melt adhesive;
the servo motor codes are used for acquiring arm rotation data, and the armrest part acceleration sensor is used for measuring vibration data of the arm;
the upper computer comprises a memory and a singlechip processor;
the data are transmitted to an upper computer by a lower computer through wired transmission, the data are processed and analyzed by a single chip processor on the upper computer to obtain relevant parameters of the collected patients, and the data and the analysis result are stored and displayed.
Furthermore, the flexible piezoresistive sensor is manufactured by weaving stainless steel fibers into metal yarns, weaving the metal yarns and common yarns, namely polyethylene yarns into a plurality of metal yarn stripes in a staggered manner to form conductive layers, vertically stacking the two conductive layers to form matrix grid arrangement, placing a flexible semiconductor piezoresistor layer in the middle of the conductive layers, connecting the stripe metal bands of the matrix grid through metal snap fasteners, and connecting the stripe metal bands with external flat cables.
Furthermore, the intelligent seat comprises a base part consisting of a stainless steel disc base and a booster oil pump hydraulic lifting rod, the seat body part comprises a component consisting of a reinforced composite straight plate and high-density sponge, and the outer surface of the seat body part is covered with a wear-resistant leather material, and the stainless steel disc base is a circular rotary hydraulic base; the circular rotary hydraulic base is connected with a seat gasket through spot welding, a reinforced composite straight plate is adhered with high-density sponge which is cut flatly to form various components, the components comprise handrails, a backrest and a cushion component, the components are fixedly connected through steel nails, and finally wear-resistant leather materials are covered on the surface of the components for packaging.
Furthermore, two straight plates are respectively adopted at the left armrest and the right armrest, a servo motor encoder is fixed at the fixed ends of the straight plates, then an acceleration sensor is placed at the suspended end of the straight plates, one end of the servo motor encoder is fixed at the corresponding position of the armrest by a hinge, a flexible piezoresistive sensor is laid and fixed on the upper surface of the straight plates to form an armrest component, the flexible piezoresistive sensor is installed at the position of a cushion, and the left armrest component and the right armrest component are symmetrical.
Furthermore, a flexible piezoresistive sensor with multiple channels (such as 16 x 16) is arranged between the high-density sponge and the abrasion-resistant leather material interlayer at the armrest parts of the chairs on two sides, and is reinforced by using an adhesive to prevent the flexible piezoresistive sensor from moving; the flexible piezoresistive sensors with multiple channels (such as 32 x 32) are arranged between the wear-resistant leather material and the high-density sponge interlayer at the position of the chair cushion, and are reinforced by using an adhesive, so that no wrinkling and no deviation are ensured, and the pressure distribution change data quality is ensured.
And the lower computer driving circuit board is used for acquiring data of the flexible piezoresistive sensor, comprises a power module drive and two multiplexers, divides the voltage of the flexible piezoresistive sensor single channel by using a divider resistor to obtain an analog voltage signal, performs digital-analog signal conversion on the analog voltage signal by using a DSP (digital signal processor), finally packages the digital voltage signals of the nodes into frames, and transmits the frames to the upper computer through a wired serial port.
Furthermore, the motor encoder driver adopts a servo motor driver with proper power (approximately equal to 200W) and low voltage (approximately 36V) and high current (approximately 7A), the driver and the upper computer adopt wired transmission, the transmission content comprises rotating speed and torque, the acceleration sensor adopts an acceleration sensor, and the acceleration sensor is directly connected with the upper computer through a flat cable to transmit attitude data of two handrail parts.
Further, a memory in the upper computer stores data acquisition and processing instructions, and when executed by the processor of the singlechip, the method executes the following steps to acquire and process the data of the Parkinson's patient:
step 1, acquiring and processing tremor data;
step 2, acquiring and processing muscle stiffness data;
step 3, acquiring and processing data in the rising stage;
and 4, acquiring and processing data on both sides of the body.
Further, the step 1, tremor data acquisition and processing specifically include:
step 1.1: collecting data received by the flexible resistance sensors at the handrail parts at the two sides; firstly, a median filter is used for eliminating noise, an interpolation method is used for up-sampling, and then a Gaussian filter is used for smoothing to obtain preprocessed data;
step 1.2: inputting the preprocessed gray low-resolution video data into a convolutional neural network for feature dimensionality reduction extraction, inputting the extracted feature data into a GRU (generalized regression) cyclic neural network for classification, wherein a cross entropy loss function is used as a loss function:
where N is the number of samples, M is the number of classes, yicIs an indicator variable; p is a radical oficTo predict the probability that a sample belongs to class c, the tremor factor S is output after predictionT;
Tremor factor STThe calculation process is as above, wherein pcFor the prediction probability of the model for level c, c is the weight corresponding to that level, and the weight of the lower level can be adjusted slightly higher. (for example, 0 grade in the original tremor grade corresponds to 1.2, 1 corresponds to 2.2, 2 corresponds to 2.1, 3 corresponds to 3, and 4 corresponds to 4, so that the aim of improving the conservative evaluation of medical staff on tremor invisible to the naked eye and improving the overall evaluation performance of equipment is achieved) the tremor factor has a strong relationship with the tremor performance of an evaluation object, and the tremor amplitude and frequency of the evaluation object can be better reflected.
The model training data can be from the marking data of the professional and can also be from the predefined data, and according to the severity of tremor of the evaluation object, the invention can divide the tremor into a plurality of grades and label the grades, so that the tremor can be evaluated more comprehensively, as shown in fig. 5.
Further, the tremor data acquisition and processing is optional, and another method is adopted, which comprises the following steps:
step 1.1: collecting data received by the flexible resistance sensors at the handrail parts at the two sides; firstly, filtering medium-high frequency noise in data by using a bilateral filter to obtain preprocessed data;
step 1.2: inputting each frame into a self-encoder to extract and reduce the dimension of the frame characteristics for the preprocessed gray low-resolution video data, and splicing the extracted characteristic data of each frame according to the sequence of the frame numbers to form a data matrix containing all the data characteristics; inputting the matrix into a support vector machine, judging whether a prediction error occurs or not if the data matrix is used for predicting the tremor degree, if the prediction error occurs, outputting 0 by the support vector machine, and if the prediction error does not occur, outputting 1 by the support vector machine; if the output of the data matrix obtained in the support vector machine is 1, inputting the data matrix into a convolutional neural network for time sequence feature extraction and classification, wherein the loss function uses a multi-class cross entropy function:
yicis an indicator variable (1 if the class sample is the same as the class of sample i, otherwise 0); p is a radical oficIs the prediction probability for a prediction sample belonging to class c. If the output of the data matrix obtained in the support vector machine is 0, the data of the batch is not classified, and the next batch of data is waited. After classifying the data, output the tremor factor:
wherein P isSVMFor support vector machine classification accuracy on training set, lkFor the prediction of tremor extent of this batch of data,/iDegree of tremor corresponding to category i, piM is the set of all tremor degrees, which is the predicted probability that the sample belongs to category i.
In the data processing model, the bilateral filter considers the intensity difference and the spatial relationship between data points at the same time, so that the bilateral filter can effectively filter out high-frequency and medium-frequency noise, and reserve the edge of the effective part of input data to avoid the ringing effect as much as possible. The self-encoder can extract the main features of the input data to the maximum extent, reduce the dimensionality of the input data and save computing resources for subsequent processing. The support vector machine plays the role of a data filter in this model. The method can filter the data which can be classified wrongly in the subsequent convolutional neural network model, and only the data which can be classified correctly can pass through, so that the accuracy of the model prediction can be improved. Convolutional layers in convolutional neural networks are used to extract timing features in the data, and fully-connected layers classify the data according to the timing features.
Further, the step 2, the acquisition and processing of the muscle stiffness data specifically includes:
step 2.1, collecting data received by the flexible resistance sensors at the handrail parts at the two sides; firstly, carrying out the same data preprocessing in the step 1.1;
step 2.2: summing the pressures obtained at the flexible resistance sensors at the positions of the single-side handrails, namely obtaining the total pressure at the positions of the handrails through the data of 16 channels by 16 channels; linear regression is performed by the encoder angle and the modulus of the acceleration sensor in three linear directions:
wherein R is the rigidity grade in the UPDRS scale;
when outputting, removing R0, and outputting as long as the latter part is used as a characteristic value as a stiffness factor:
the output value is a strong direct factor and is a multi-sensor fusion value R
0Alpha, beta and lambda are regression variables, P is the total pressure value of the handrail, S is the rotation angle of the encoder,
is the mode of the three-dimensional accelerometer.
Further, the acquiring and processing of the data in the starting stage of step 3 specifically includes:
the rising data acquisition stage is divided into three stages: a gravity center transfer stage, a foot supporting stage and a separating rising stage; and (4) calculating the total pressure value and the rising time of each stage of the three stages respectively.
Three-stage division:
A. a gravity center transfer stage: the human body is supported by the armrests, the gravity center is gradually transferred from the buttocks to the feet, but the buttocks still have gravity. The behavior on the flexible pressure sensor data is as follows: the total pressure value of the sensor of the cushion part is reduced, the gravity center is changed, and the stage can be judged by setting a gravity center change threshold value.
B. A step supporting stage: the human body is supported by the armrests, the buttocks are separated from the chair, and no gravity exists in the cushion part. The expression on the flexible pressure sensor data is that the total pressure value of the sensor of the cushion part is zero, the total pressure sensor of the armrest part is obviously increased compared with the first stage, and the first stage and the second stage can be distinguished by judging whether the gravity of the cushion part exists or not.
C. A separation rising stage: the human body is supported by the feet, and no gravity exists in the seat cushion and the armrest part in the stage of gradually standing. The second and third stages can be distinguished by determining whether pressure is present on the armrest.
Specifically, the feature calculation at each stage is as follows:
1) total pressure value:
calculating the total pressure of a frame in the video-like data, wherein: i, j are pixel points, i.e. sensing points, located in i rows and j columns, m, n are the number of rows and columns of the matrix, AijPressure values of i rows and j columns;
2) change of center of gravity:
firstly, establishing a Cartesian coordinate system for a frame, adding the gravity x coordinates of all pixel points and dividing the gravity x coordinates by the number of the pixel points to obtain the gravity center position in the x direction under the condition that the pressure in the frame is greater than a specific value, obtaining the gravity center position in the y direction in the same way, and judging as a first stage if the change value of the gravity center position in the set direction exceeds a set threshold value;
3) duration of the phase: and when the gravity center change threshold frame of the first stage is reached, marking the frame as the ending frame of the first stage, recording the corresponding timestamp, and obtaining the stage duration by utilizing the two timestamps.
Further, the step 4 of collecting and processing bilateral body data specifically includes:
the tremor factor data, the muscle strength data and the maximum pressure conditions of the armrests on the two sides in the rising process of the patient are weighted and calculated, and the unbalance degree of the limbs on the two sides can be obtained:
S=aST+bSR+cP
wherein S is a single-side limb index, a, b and c are weights of each parameter, STIs tremor factor, SRMuscle rigidity factor, P is the maximum pressure of the armrest in the rising stage; finally, the left index was used to divide the right index to obtain the degree of bilateral difference (%)
Has the advantages that:
1. the design scheme in the prior art is improved, and as the pressure sensors adopted in the prior art are all traditional single-point piezoresistive sensors and do not use a special driving circuit board for data acquisition, the impedance (resistance) of arm parts cannot be accurately and completely reflected, and the data refresh rate is low, the data acquisition and processing equipment for similar muscle stiffness evaluation is improved;
2. the intelligent chair carries out digital acquisition and calculation on the motion data and the rising action process of the patient, and the prior art has no similar method for calculating the type of data and has no system for combining muscle rigidity evaluation and tremor evaluation of the Parkinson patient;
3. the invention designs the special sensor, the special driving circuit board and the special seat, so that medical staff can use the device more conveniently and can evaluate the patient without sitting posture temporarily, thereby ensuring the safety of the patient to a greater degree and realizing non-invasive detection.
Drawings
FIG. 1 is a schematic view of a flexible piezoresistive sensor matrix according to the present invention;
FIG. 2 is a schematic diagram of a multifunctional digital evaluation intelligent seat according to the present invention;
FIG. 3 is a schematic view of a multifunctional digital evaluation intelligent seat structure according to the present invention;
FIG. 4 is a pressure distribution visualization display diagram;
FIG. 5 is a tremor data processing flow diagram;
FIG. 6 is a flow chart of yet another example of tremor data processing.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person skilled in the art based on the embodiments of the present invention belong to the protection scope of the present invention without creative efforts.
According to one embodiment of the invention, the multifunctional digital evaluation intelligent seat is provided, wherein flexible piezoresistive sensors are respectively installed at a cushion part and an armrest part of the intelligent seat, a servo motor encoder and an acceleration sensor are additionally installed at the armrest part, pressure distribution change data of a contact surface above the flexible piezoresistive sensors, rotation data of the servo motor encoder and data of the armrest part acceleration sensor are transmitted through a wired serial port protocol, the data are sent to an upper computer by a lower computer, the data are processed and analyzed by the upper computer to obtain relevant parameters of a collected patient, and the data and an analysis result are stored.
According to one embodiment of the invention, the flexible piezoresistive sensor comprises: compared with the copper-silver alloy adopted in the prior art, the stainless steel conductive fiber disclosed by the invention has the advantages that the cost can be controlled while the higher conductivity is ensured, the weight is lighter and softer, and the cost is greatly reduced; the flexible semiconductor piezoresistor layer is formed by staggering silicon carbide fibers and polyethylene fibers. Wherein, two-layer conducting layer are ninety degrees horizontal vertical arrangement to place one deck the flexible semiconductor varistor layer in two-layer conducting layer middle, can use the sewing machine to fix three-layer sewing line (guarantee that there is not the portion of puckering between three-layer intermediate layer) afterwards, and use the hot melt adhesive to consolidate. When the flexible piezoresistive sensor is manufactured, stainless steel fibers are woven into metal yarns, the metal yarns and common yarns, namely polyethylene yarns, are woven in a staggered mode to form a plurality of metal yarn stripes to form a conductive layer, two conductive layers are vertically stacked to form matrix grid arrangement, a flexible semiconductor piezoresistor layer is placed in the middle of the conductive layer, metal strips of the stripes of the matrix grid are connected with an external lead through good conductors (for example, metal snap fasteners are used as the good conductors, and connection stability can be well guaranteed), and the flexible piezoresistive sensor is manufactured;
the intelligent seat comprises a base part consisting of a stainless steel disc base and a booster oil pump hydraulic lifting rod (the lifting rod is positioned on the back of a seat and is convenient for medical staff to adjust the height), the chair body part mainly comprises a component consisting of a reinforced composite straight plate and high-density sponge, and the stainless steel disc base is a circular rotary hydraulic base covered with wear-resistant leather materials on the outer surface; the manufacturing process of the intelligent seat comprises the following steps: the circular rotary hydraulic base is connected with a seat gasket through spot welding, a reinforced composite straight plate is adhered with high-density sponge which is cut flatly to form various components, the components comprise handrails, a backrest and a cushion component, the components are fixedly connected through steel nails, and finally wear-resistant leather materials are covered on the surface of the components for packaging. The cutting flattening is to ensure that the pressure distribution can be uniform and better reflect the pressure distribution condition.
According to an embodiment of the present invention, as shown in fig. 2, the armrest part is implemented by using two straight plates at the left and right armrests, respectively, fixing the servo motor encoder at the fixed end 3 of the straight plate, then placing the acceleration sensor at the suspended end 1 of the straight plate, and fixing one end of the servo motor encoder at the corresponding part of the armrest of the seat by using a hinge. As shown in fig. 2: an acceleration sensor is arranged at the position of a hanging end 1 of a straight plate shown in the figure, a flexible piezoresistive sensor is laid and fixed on the upper surface of the straight plate to form a handrail component 2, a servo motor encoder is arranged at the position of a fixed end 3 at the tail end of the straight plate, the flexible piezoresistive sensor is arranged at the position of a cushion 4, and a handrail part 5 is symmetrical to a handrail part at the other side.
According to one embodiment of the present invention, it is preferable to place the multi-channel (e.g. 16 x 16) flexible piezoresistive sensors between the high density sponge and the abrasion resistant leather sandwich at the armrest portion of the chair on both sides, and to use strong adhesive to reinforce and prevent the movement. Flexible piezoresistive sensors in multiple channels (e.g., 32 x 32) are placed between a layer of abrasion resistant leather material and a high density sponge in the seat cushion area of the chair and reinforced with a high strength slow drying adhesive. The high-strength slow-drying glue can ensure no wrinkling and no deviation, thereby ensuring the quality of pressure distribution change data;
according to an embodiment of the present invention, as shown in fig. 1, the lower computer driving circuit board of the present invention is configured to acquire data of a flexible pressure sensor, and includes a 5V power module driver and two 3.3V multiplexers, and divides a flexible piezoresistive sensing single channel voltage by using a voltage dividing resistor to obtain an analog voltage signal with an appropriate size, and then performs digital-to-analog signal conversion on the analog voltage signal by using a DSP, and finally encapsulates the digital voltage signals of a plurality of nodes into frames, and transmits the frames to an upper computer through a wired serial port or transmits the frames to the upper computer through bluetooth.
The motor encoder driver adopts a servo motor driver with proper power (approximately equal to 200W) and low voltage (approximately 36V) and high current (approximately 7A), the driver and an upper computer adopt wired serial port transmission, and the transmission content comprises rotating speed and torque. The acceleration sensor adopts an acceleration sensor and is directly connected with an upper computer through a flat cable to transmit the posture data of the two handrail parts.
According to a preferred embodiment of the present invention, the flexible piezoresistive sensor is disposed between a high-density sponge and a wear-resistant leather interlayer of the chair, and is fixed by a cloth-covered double-sided adhesive tape, and a data output cable of the flexible piezoresistive sensor is connected to a circuit board fixed at a backrest of the chair, a power interface of the driving circuit board is a 5V conventional USB-type a power interface, a motor encoder is connected by solder, and a transformer module (e.g., 220V-5V, such as 220V-36V) is installed at the same time. And then the assembly of the intelligent seat is completed.
Preferably, the upper computer is realized by an ARM platform single chip microcomputer, clicking and inputting operations are performed through a touch screen, the upper computer system is a Ubuntu 16.04 system, the software system is compiled by a cross-platform QT development framework, and the programming language is C + +. The upper computer working process comprises the following steps:
confirming start/stop data transmission, receiving an original data frame of a lower computer, unpacking the original data, preprocessing the data (eliminating noise and storing data), and then visually displaying the processed data on an interface of the upper computer, as shown in fig. 4, wherein the display content comprises: the pressure of each node of the flexible piezoresistive sensor (represented by different colors) and the total pressure change line graph of the surface of the flexible piezoresistive sensor.
According to one embodiment of the invention, the parkinson patient data acquisition and processing using the aforementioned smart chair has the following improvements:
1. the data uses a computer vision algorithm which cannot be used by the traditional piezoresistive sensor, and specifically, the data is different from the original single-point sensor which is only pressure change data changing along with time, and the data of the flexible piezoresistive sensor is as follows: multiple channels (e.g. 64 × 32 — 2048 points), high refresh rate (up to 40Hz), and more information and features than single point sensing data. If the data is treated as gray video, for example, in tremor recognition, the CNN + GRU model can be used to extract and classify features.
2. Unlike conventional piezoresistive sensors, more complex pre-processing is required. For example, the collected data may be regarded as similar video data, and has a low resolution (e.g. 64 × 32 pixels), and only has the characteristic of information of pressure magnitude change, so that it may be called: grayscale low resolution type video data. Therefore, for this kind of video data, it is necessary to perform a data preprocessing process on the video data, which includes first using median filtering to eliminate possible crosstalk noise of the sensor (i.e., interference noise generated by mutual influence between conductive metal strips), using interpolation to perform upsampling to improve data (video) resolution, using a smoothing method commonly used in digital image processing to uniformly smooth the image, and filtering part of the noise.
According to one embodiment of the invention, the memory of the upper computer stores data acquisition and processing instructions, and when executed by the processor of the singlechip, the method performs the following steps to acquire and process the Parkinson's patient data:
step 1, tremor data acquisition and processing:
step 1.1: collecting data received by the flexible resistance sensors at the handrail parts at the two sides; firstly, a median filter is used for eliminating noise, an interpolation method is used for up-sampling, and then a Gaussian filter is used for smoothing to obtain preprocessed data;
step 1.2: inputting the preprocessed gray low-resolution video data into a convolutional neural network for feature dimensionality reduction extraction, inputting the extracted feature data into a GRU (generalized regression) cyclic neural network for classification, wherein a cross entropy loss function is used as a loss function:
where N is the number of samples, M is the number of classes (e.g., in this application scenario: five total levels 0-4), yicIs an indicator variable (1 if the class sample is the same as the class of sample i, otherwise 0); p is a radical oficIs the prediction probability for a prediction sample belonging to class c. After prediction, a tremor factor S is outputT;
Tremor factor STThe calculation process is as aboveWherein p iscFor the prediction probability of the model for level c, c is the weight corresponding to that level, and the weight of the lower level can be adjusted slightly higher. (for example, 0 grade in the original tremor grade corresponds to 1.2, 1 corresponds to 2.2, 2 corresponds to 2.1, 3 corresponds to 3, and 4 corresponds to 4, so that the aim of improving the conservative evaluation of medical staff on tremor invisible to the naked eye and improving the overall evaluation performance of equipment is achieved) the tremor factor has a strong relationship with the tremor performance of an evaluation object, and the tremor amplitude and frequency of the evaluation object can be better reflected.
The model training data can be from the labeled data of professionals and can also be from predefined data, and according to the severity of tremor of an evaluation object, the invention can divide the tremor into a plurality of grades and label the grades, so that the tremor can be evaluated more comprehensively, as shown in fig. 5.
According to yet another embodiment of the present invention, another method of parkinson's patient data acquisition and processing tremor assessment data is provided:
step 1.1: collecting data received by the flexible resistance sensors at the handrail parts at the two sides; firstly, filtering medium-high frequency noise in data by using a bilateral filter to obtain preprocessed data;
step 1.2: inputting each frame into a self-encoder to extract and reduce the dimension of the frame characteristics for the preprocessed gray low-resolution video data, and splicing the extracted characteristic data of each frame according to the sequence of the frame numbers to form a data matrix containing all the data characteristics; inputting the matrix into a support vector machine, judging whether a prediction error occurs or not if the data matrix is used for predicting the tremor degree, if the prediction error occurs, outputting 0 by the support vector machine, and if the prediction error does not occur, outputting 1 by the support vector machine; if the output of the data matrix obtained in the support vector machine is 1, inputting the data matrix into a convolutional neural network for time sequence feature extraction and classification, wherein the loss function uses a multi-class cross entropy function:
yicis an indicator variable (1 if the class sample is the same as the class of sample i, otherwise 0); p is a radical oficIs the prediction probability for a prediction sample belonging to class c. If the output of the data matrix obtained in the support vector machine is 0, the data of the batch is not classified, and the next batch of data is waited. After classifying the data, output the tremor factor:
wherein P isSVMFor support vector machine classification accuracy on training set, lkFor the prediction of tremor extent of this batch of data,/iDegree of tremor corresponding to category i, piM is the set of all tremor degrees, which is the predicted probability that the sample belongs to category i.
In the data processing model, the bilateral filter considers the intensity difference and the spatial relationship between data points at the same time, so that the bilateral filter can effectively filter out high-frequency and medium-frequency noise, and reserve the edge of the effective part of input data to avoid the ringing effect as much as possible. The self-encoder can extract the main features of the input data to the maximum extent, reduce the dimensionality of the input data and save computing resources for subsequent processing. The support vector machine plays the role of a data filter in this model. The method can filter the data which can be classified wrongly in the subsequent convolutional neural network model, and only the data which can be classified correctly can pass through, so that the accuracy of the model prediction can be improved. Convolutional layers in convolutional neural networks are used to extract timing features in the data, and fully-connected layers classify the data according to the timing features.
Step 2, muscle stiffness assessment data acquisition and processing
Step 2.1: collecting data received by the flexible resistance sensors at the handrail parts at the two sides; firstly, carrying out the same data preprocessing in the step 1.1;
step 2.2: summing the pressures obtained at the flexible resistance sensors at the positions of the single-side handrails, namely obtaining the total pressure at the positions of the handrails through the data of 16 channels by 16 channels; linear regression is performed by the encoder angle and the modulus of the acceleration sensor in three linear directions:
wherein, R is the rigidity grade (0-4 grade) in the UPDRS scale;
when outputting, R0 may be removed here, as long as the latter part serves as a strong factor as a characteristic value, that is, outputting:
the output value is a strong direct factor (multi-sensor fusion value), R
0Alpha, beta and lambda are regression variables, P is the total pressure value of the handrail, S is the rotation angle of the encoder,
is the mode of the three-dimensional accelerometer.
Step 3, acquiring and processing data in the rising stage
The rising data acquisition stage is divided into three stages: a gravity center transfer stage, a foot supporting stage and a separating rising stage; and (4) calculating the total pressure value and the rising time of each stage of the three stages respectively.
Three-stage division:
A. a gravity center transfer stage: the human body is supported by the armrests, the gravity center is gradually transferred from the buttocks to the feet, but the buttocks still have gravity. The behavior on the flexible pressure sensor data is as follows: the total pressure value of the sensor of the cushion part is reduced, the gravity center is changed, and the stage can be judged by setting a gravity center change threshold value.
B. A step supporting stage: the human body is supported by the armrests, the buttocks are separated from the chair, and no gravity exists in the cushion part. The expression on the flexible pressure sensor data is that the total pressure value of the sensor of the cushion part is zero, the total pressure sensor of the armrest part is obviously increased compared with the first stage, and the first stage and the second stage can be distinguished by judging whether the gravity of the cushion part exists or not.
C. A separation rising stage: the human body is supported by the feet, and no gravity exists in the seat cushion and the armrest part in the stage of gradually standing. The second and third stages can be distinguished by determining whether pressure is present on the armrest.
Specifically, the feature calculation at each stage is as follows:
1) total pressure value:
calculating the total pressure of a frame in the video-like data, wherein: i, j are pixel points (sensing points) positioned in i rows and j columns, m, n are the row number and column number of the matrix, AijI rows and j columns of pressure values.
2) Change of center of gravity:
firstly, a Cartesian coordinate system is established for a frame, for the condition that the pressure in the frame is greater than a specific value, the gravity x coordinates of all pixel points (sensing points) are added and divided by the number of the pixel points, so that the gravity center position in the x direction can be obtained, and similarly, the gravity center position in the y direction can also be obtained, and if the change value of the gravity center position in the set direction exceeds a set threshold value, the first stage can be judged.
3) Duration of the phase: the user (medical staff) clicks the start of the getting-up evaluation as the initial frame of the first stage, and records the corresponding time stamp, when the first stage gravity center change threshold frame is reached, the frame is marked as the end frame of the first stage, the corresponding time stamp is recorded, and the stage duration is obtained by utilizing the two time stamps. The last two stages are as above.
Step 4, collecting and processing data on two sides of the body:
the tremor factor data, the muscle strength data and the maximum pressure conditions of the armrests on the two sides in the rising process of the patient are weighted and calculated, and the unbalance degree of the limbs on the two sides can be obtained:
S=aST+bSR+cP
wherein S is a single-side limb index, a, b and c are weights of each parameter, STIs tremor factor, SRMuscle rigidity factor, P is the maximum pressure of the armrest in the rising stage; finally, the left index is used for dividing the right index to obtain the difference degree (%) of the bilateral limbs;
although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, but various changes may be apparent to those skilled in the art, and it is intended that all inventive concepts utilizing the inventive concepts set forth herein be protected without departing from the spirit and scope of the present invention as defined and limited by the appended claims.