Detailed Description
Other advantages and effects of the present disclosure will be readily apparent to those skilled in the art from the following detailed description of the embodiments of the disclosure given by way of specific examples. The disclosure may be embodied or applied in other specific forms and details, and various modifications and alterations may be made to the details of the disclosure in various respects, all without departing from the spirit of the disclosure. It should be noted that, without conflict, the embodiments of the present disclosure and features of the embodiments may be combined with each other.
The embodiments of the present disclosure will be described in detail below with reference to the attached drawings so that those skilled in the art to which the present disclosure pertains can easily implement the same. The present disclosure may be embodied in many different forms and is not limited to the embodiments described herein.
In the description of the present disclosure, references to the terms "one embodiment," "some embodiments," "examples," "particular examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or a group of embodiments or examples. Furthermore, various embodiments or examples, as well as features of various embodiments or examples, presented in this disclosure may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the representations of the present disclosure, "a set" means two or more, unless specifically defined otherwise.
For the purpose of clarity of the present disclosure, components that are not related to the description are omitted, and the same or similar components are given the same reference numerals throughout the specification.
Throughout the specification, when a device is said to be "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" with other elements interposed therebetween. In addition, when a certain component is said to be "included" in a certain device, unless otherwise stated, other components are not excluded, but it means that other components may be included.
Although the terms first, second, etc. may be used herein to connote various elements in some examples, the elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, a first interface, a second interface, etc. Furthermore, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" specify the presence of stated features, steps, operations, elements, modules, items, categories, and/or groups, but do not preclude the presence, presence or addition of one or more other features, steps, operations, elements, modules, items, categories, and/or groups. The terms "or" and/or "as used herein are to be construed as inclusive, or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a, A is as follows; b, a step of preparing a composite material; c, performing operation; a and B; a and C; b and C; A. b and C). An exception to this definition will occur only when a combination of elements, functions, steps or operations are in some way inherently mutually exclusive.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the language clearly indicates the contrary. The meaning of "comprising" in the specification is to specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of other features, regions, integers, steps, operations, elements, and/or components.
Although not differently defined, including technical and scientific terms used herein, all terms have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The term append defined in commonly used dictionaries is interpreted as having a meaning that is consistent with the meaning of the relevant technical literature and the currently prompted message, and is not excessively interpreted as an ideal or very formulaic meaning, so long as no definition is made.
Usually, in clinical practice, the stroke hemiplegia user is usually subjected to rehabilitation training by using sitting station training except conventional rehabilitation training. During rehabilitation training, a user can dynamically change among various postures such as sitting, standing and the like. In this process, it is necessary to monitor the user's balance, i.e., the center of gravity, to see the user's rehabilitation.
How to accurately, stably and real-timely determine the gravity center change of a user in the posture change process so as to help the analysis of the rehabilitation situation of the user is a technical problem to be solved in the industry.
In view of this, rehabilitation training assistance devices are provided in embodiments of the present disclosure to solve the above problems.
At present, the human body balance capacity is detected mainly through two data sources of an image/video and a sensor, and the gravity center is estimated by using physical sensor data such as an accelerometer, a gyroscope and the like by a sensor-based method.
In the embodiments of the present disclosure, a barycentric detection scheme of a pressure sensor is employed. The gravity center detection method based on the pressure sensor mainly calculates a pressure center through pressure distribution applied by a human body on a supporting surface, and then utilizes the movement of the pressure center to represent the movement of the gravity center of the human body on the supporting surface. The center of gravity refers to the centroid or mass point of the body, typically located in the lower half of the torso, near the hips. When a person stands or performs various actions, their center of gravity will change with the movement of the body, but it must be located on the support surface. Thus, the center of pressure may be regarded as a projection of the center of gravity on the support surface, and a change in the center of pressure on the support surface may represent a change in the center of gravity, and then a measurement of the center of gravity of the human body in the support surface may be simplified to a measurement of the center of pressure based on the pressure sensor.
As shown in fig. 1, a schematic structural diagram of a rehabilitation training assistance device according to an embodiment of the present disclosure is shown.
The rehabilitation training aid 1 comprises a standing unit and a sitting unit.
The standing unit is used for standing training of a user in rehabilitation training. As an example, the standing unit includes a first load carrying platform 11 and a pair of first armrests 12a, 12b. The first carrying platform 11 is used for a user to stand. Illustratively, the first carrying platform 11 may include a left carrying sub-platform 111 and a right carrying sub-platform 112, which are used for standing on both feet of the user. The left carrying sub-platform 111 and the right carrying sub-platform 112 may have square shapes as shown in the figure, and may be spliced with each other to form the first carrying platform 11.
The pair of first armrests 12a, 12b are respectively located at two sides of the first carrying platform 11. As an example, the pair of first handrails 12a, 12b may be located at the front side of the first loading platform 11 and extend backward to both sides of the first loading platform 11. Each of the first armrests 12a, 12b may be of a rectilinear configuration. As an example, the pair of first armrests 12a, 12b are fixed at the bottom to a transverse connection plate 15, and the connection plate 15 is available for the user to tread. The pair of first armrests 12a, 12b may be respectively disposed on a column to have a certain height. As an example, each of the first handrails 12a, 12b may be connected to the upright by a mechanism that can be lifted in the longitudinal direction so as to be position-adjustable in the longitudinal direction. As an example, each of the first armrests 12a, 12b may also be linked to the upright by a mechanism that rotates in the lateral direction so as to be angularly adjustable in the lateral direction.
As an example, the standing unit may be located on a first base 16, the sitting unit may be located on a second base 17, and the first base 16 and the second base 17 may be fixedly connected or may be integrally formed. The fixed connection can be in a fixing mode such as clamping, screw locking, welding and the like.
The sitting unit is used for sitting training of a user in rehabilitation training. The sitting unit is communicated with the standing unit, namely, a user can move between the two units and change sitting and standing postures. As an example, the seating unit may be located at the rear side of the first loading platform 11, opposite to the front and rear of the pair of first handrails 12a, 12 b. As an example, the seating unit includes a second carrying platform 13 and a pair of second armrests 14a, 14b, and the pair of second armrests 14a, 14b are respectively located at two sides of the second carrying platform 13. As an example, the second armrests 14a, 14b may be adjustable in longitudinal direction and/or rotational angle by means of a lifting mechanism, a rotating mechanism, or the like. In an implementation example, the lifting mechanism may be implemented by a sliding mechanism, for example based on a slide and a rail, a slide and a screw, and the turning mechanism may be implemented by a mechanism, for example a hinge, a pin joint, a gear transmission, etc. As an example, the second carrying platform 13 may be square in shape as shown in the figures.
As an example, the position of the first load-bearing platform 11 may be adjustable or fixed. The position of the second carrying platform 13 may be adjustable or fixed. In a further example, the adjustability may be in a transverse plane and/or in a longitudinal direction.
The sitting unit can be arranged on a stand column so as to have a certain height, and the height can be matched with the height of the legs and buttocks of the user. In an example of practical application, when the user is going to change from the standing position to the sitting position, the user holds the first armrests 12a, 12b with his hands, and moves to the second armrests 14a, 14b, and then moves to sit on the second carrying platform 13 with the second armrests 14a, 14b as supports.
To facilitate walking training of the user, in still another example, the rehabilitation training assistance device 1 may further include a carry-on unit (not shown) disposed in communication with the standing unit, such as in front of the standing unit. The travel location unit may include a third load platform (not shown) for standing for the user to move and then stand. The travel position unit may further include a pair of third handrails (not shown) disposed at both sides of the third loading platform, for example. Of course, the user may also multiplex the pair of first armrests 12a, 12b, the third being not necessary.
For monitoring the center of gravity of the user, the first carrying platform 11, each first armrest 12a, 12b, the second carrying platform 13 and each second armrest 14a, 14b are provided with a pressure sensor group, each pressure sensor group comprises a plurality of pressure sensors, and each pressure sensor detects a pressure signal of the position where the pressure sensor is located.
As shown in fig. 2, a schematic partial structure of the first armrest 12a on the left side and the pressure sensor set arrangement on the left carrier sub-platform 111 in the embodiment of the present disclosure is shown. It will be appreciated that the right first armrest 12b and the right carrying sub-platform 112 may be of identical symmetrical construction.
In fig. 2, the first handrail 12a extends along a straight line, and the pressure sensor group on the first handrail 12a includes at least two pressure sensors 121a, 122a, which are respectively disposed near opposite ends of the first handrail 12, preferably symmetrically disposed. The pressure sensor group on the first handrail 12a can realize one-dimensional pressure center and pressure measurement on the first handrail 12.
In fig. 2, four pressure sensors 1111, 1112, 1113, 1114 are symmetrically disposed at four corners of the left carrying sub-platform 111, so as to realize two-dimensional pressure center and pressure measurement on the left carrying sub-platform 111.
It will be appreciated that the arrangement of the pressure sensor groups on the first handrail 12b and the pair of second handrails 14a, 14b on the right side may be the same as the arrangement of the pressure sensor groups on the first handrail 12a on the left side in fig. 2, i.e. at least two pressure sensors are used, preferably symmetrically located near the two ends of the handrail.
It is to be understood that the arrangement of the pressure sensor groups on the right carrying sub-platform 112 and the second carrying platform 13 may be the same as the arrangement of the pressure sensor groups on the left carrying sub-platform 111 in fig. 2, that is, at least four pressure sensors are arranged at four corners of the platform, and preferably symmetrically arranged.
It should be noted that the shape of each of the first armrests 12a, 12b, each of the second armrests 12a, 12b, the first carrying platform 11, and the second carrying platform 13 may be variable, and the layout of the pressure sensor group may be changed or may not be changed.
It will be appreciated that if a third load-bearing platform and a third armrest are provided, the third load-bearing platform and the third armrest are also provided with a pressure sensor group.
Each pressure sensor group is used for being connected with external communication to output a pressure signal. To distinguish each pressure sensor, each pressure sensor may have a unique sensor ID and may be added to the output pressure signal for transmission. Referring to fig. 3, each of the pressure sensor sets may be communicatively coupled to a computer device 2, illustratively pressure sensors 121a, 122a on the left first armrest 12a, and pressure sensors 1111, 1112, 1113, 1114 on the left load-bearing sub-platform 111. The computer device 2 may be a terminal independent of the rehabilitation aid device, such as a server, desktop, notebook, tablet, smart phone or other type of terminal. Alternatively, the computer device 2 may be a controller integrated in the rehabilitation training aid.
As examples, the communication connection may be a wired connection, a wireless connection, or a combination of wired and wireless connections. The wired connection may be an ethernet port, serial communication, or the like, and the wireless connection may be based on one or more of Wi-Fi technology, near field communication (Nearfield communication, NFC) technology, infrared (IR) technology, global system for mobile communications (Global System for Mobile communications, GSM), general packet radio service (General Packet Radio Service, GPRS), code Division multiple access (Code Division MultipleAccess, CDMA), wideband Code Division multiple access (Wideband Code Division multiple access, WCDMA), time Division multiple access (Time-Division Code Division Multiple Access, TD-SCDMA), long term evolution (Long Term Evolution, LTE), blueTooth (BlueTooth, BT), or the like, for example. By way of example, the communication connection may be based on a local area network, a wide area network, or a combination of local area and wide area networks. For example, a combination of a WiFi local area network and a fiber optic network of a communications carrier, etc.
As an example, the computer device 2 may perform a method of acquiring a center of pressure to calculate position information of a global center of pressure determining a center of gravity of a corresponding user from pressure signals provided in real time by each of the pressure sensor groups.
The implementation principle is explained below. As shown in fig. 4, a schematic diagram of calculating position information of a global pressure center according to a pressure sensor group in an embodiment of the present disclosure is shown.
In fig. 4, a plurality of functional modules are provided for a specific implementation, including a signal acquisition module, a signal recognition module, and a model calculation module.
The signal acquisition module comprises all pressure sensor groups. Specifically, a set of pressure sensors on the first load carrying platform and the second load carrying platform (abbreviated as "platform pressure sensors" in the figure), and a set of pressure sensors on the first handrail and the second handrail (abbreviated as "handrail pressure sensors" in the figure). Each pressure sensor converts the collected pressure signal into an electric signal and outputs the electric signal. The pressure signal is converted into a quantized signal through the signal identification module and is input into the model calculation module. The signal recognition module may be implemented for an analog-to-digital converter (ADC), i.e. the signal recognition module converts a continuous analog signal (pressure signal) into a digital signal (quantized signal) output, for example. Digital signal processing may be performed based on digital signals, so the signal recognition module also illustratively contains some digital processing circuitry, such as filtering circuitry, etc.
The model calculation module is located in the computer device and can be realized by hardware circuit/software/hardware combination. The model calculation module can be pre-configured with a plurality of calibration models, a pressure calibration model, a pressure center calibration model and an integrated pressure center model. Further, according to the difference between the armrest and the carrying platform, the pressure calibration model may be further subdivided into a platform pressure calibration model of the corresponding carrying platform (such as the first carrying platform and the second carrying platform of the same type of pressure sensor layout), an armrest pressure calibration model of the corresponding armrest (such as the first armrest and the second armrest of the same type of pressure sensor layout), a platform pressure center calibration model of the corresponding carrying platform (such as the first carrying platform and the second carrying platform of the same type of pressure sensor layout), an armrest pressure center calibration model of the corresponding armrest (such as the first armrest and the second armrest of the same type of pressure sensor layout), and the like.
The quantized signals output by the signal recognition module are calculated through a pressure calibration model and a pressure center calibration model to obtain pressure information and pressure center position information on a corresponding platform and an armrest; then, corresponding to the position information of each local pressure and local pressure center of each platform and each armrest in the standing and sitting states, the position information of the global pressure center corresponding to the whole user can be obtained through the integrated pressure center model, and the quality of the corresponding user can be obtained.
As shown in fig. 5, a flow chart of a method for acquiring a pressure center in an embodiment of the disclosure is shown.
In fig. 5, the method includes:
step S501: and respectively acquiring the local pressure born by the first bearing platform, the first handrail, the second bearing platform and the second handrail and the position information of the local pressure center.
As shown in fig. 6, the step S501 may further include:
step S601: and calculating corresponding local pressure according to the pressure signal of each pressure sensor group based on the pressure calibration model.
The pressure calibration model is calibrated with a first relation function of pressure signals and local pressure of the pressure sensor group in advance.
Step S602: and calculating the position information of the corresponding local pressure center according to the pressure signal of each pressure sensor group based on the pressure center calibration model.
The pressure calibration model is calibrated with a second relation function of the pressure signal of the pressure sensor group and the position information of the local pressure center in advance.
The description is given by way of specific examples. Set a set of pressure data (i.e. 4 quantized signals) of the pressure sensor at the 4 corners of the left load-bearing sub-platform asThe set of pressure data of the pressure sensor at the angle 4 of the right bearing sub-platform is The set of pressure data for the left first handrail is +.>The set of pressure data for the right first handrail is +.>The pressure data of the second bearing platform is +.>The set of pressure data for the left second handrail is +.>The set of pressure data for the right second handrail is +.>
As shown in FIG. 7, local coordinate systems in various transverse planes, such as the left load-bearing sub-platform 111 coordinate system, can be established on each load-bearing platform and handrailRight bearing sub-platform 112 coordinate System->Left first armrest 12a coordinate system +.>Right first armrest 12b coordinate system +.>The second bearing platform 13 coordinate system->Left second handrail 14a coordinate system +.>Right second handrail 14b coordinate system +.>The positional information of the local center of pressure of each platform, armrest, may be represented by the abscissa and ordinate in the local coordinate system in the transverse plane in which it lies. The position information and pressure data of the corresponding pressure center can be calculated through the corresponding calibration model, and the left first armrest and the left bearing sub-platform are taken as examples:
wherein G represents the pressure on the platform/handrail;
x OXY ,y OXY representing coordinates of a center of pressure on the platform/armrest in a coordinate system O-XY;
f(.) gra a first relation function representing a corresponding pressure calibration model, and obtaining the pressure on the corresponding armrest/platform according to the data of the plurality of sensors;
And a second relation function representing the corresponding pressure center calibration model is used for obtaining the pressure center coordinate under the coordinate system O-XY according to the data of the plurality of sensors. For example, the pressure center calibration model may be constructed based on the principle of moment balance, for example, the moment at the position of each pressure sensor is equal to the moment at the same pressure center. The moment of the pressure center can be obtained according to the integral pressure obtained by the pressure calibration model and the position information of the pressure center.
Similarly, the pressure of the right bearing sub-platform is as follows according to the pressure calibration model and the pressure center calibration modelAnd a local pressure center of +.>The first handrail on the right side has a pressure of +>And the local pressure center isThe pressure of the second bearing platform is +.>And a local pressure center of +.>The pressure of the second handrail at the left side is +.>And a local pressure center of +.>The second handrail on the right side has a pressure of +>And the local pressure center is
Step S502: the global pressure at the global pressure center is obtained based on the local pressure of each local pressure center, and the position information of the global pressure center is obtained based on the position information of each local pressure center and the global pressure.
As shown in fig. 8, a specific implementation flowchart of step S502 in the embodiment of the disclosure is shown.
Step S502 includes:
step S801: and converting the position information of each local pressure center from the local coordinate system of each local pressure center to a unified coordinate system.
Step S802: the abscissa of the global pressure center is determined based on the moment balance between each local pressure center and the global pressure center on the horizontal axis in the unified coordinate system, and the ordinate of the global pressure center is determined based on the moment balance between each local pressure center and the global pressure center on the vertical axis in the unified coordinate system.
Wherein the global pressure is the sum of the local pressures.
Continuing with the example of fig. 6, the implementation principle of the flow in fig. 8 will be described.
The unified coordinate system may be selected from the local coordinate systems, or may be set independently. Illustratively, the coordinate system of the second bearing platformIn the global coordinate system, the coordinates of the position information of the global pressure center in the unified coordinate system are set to +.>Global pressure is set to G all Then G can be calculated all The method comprises the following steps:
corresponding to step S702, according to the principle that the local pressure center and the global pressure center are respectively balanced in moment in the lateral and longitudinal positions, the abscissa and the ordinate of the global pressure center can be obtained respectively:
Wherein,representing a coordinate system O 1 -x-axis coordinates of the XY origin in the coordinate system O-XY;
representing a coordinate system O 1 -y-axis coordinates of the XY origin in the coordinate system O-XY; it is to be understood that O-XY here is a unified coordinate system, i.e.e.as described above +.>O 1 XY represents the local coordinate system, i.e.e.g. +.>
By superimposing on the abscissa of the local centre of pressureSuperimposed on the ordinate +.>Namely, each office as in step S701 is completedAnd converting the coordinate position of the part coordinate system into a unified coordinate system, and further calculating the coordinate of the global pressure center according to the principle of moment balance in the two formulas according to the converted local pressure center coordinate.
It will be appreciated that in some embodiments, the pressure signals of each of the pressure sensor sets are acquired multiple times along the time dimension for obtaining global pressure at each global pressure center distributed along the time dimension and further obtaining location information. The position information of each global pressure center distributed along the time dimension can form position sequence information, and the position sequence information can indicate the gesture change, speed and the like of a user in the rehabilitation training process and can be used for analyzing the rehabilitation training effect.
As shown in fig. 9, a schematic structural diagram of a computer device in an embodiment of the present disclosure is shown. The computer device 900 may be the computer device 2 of fig. 3.
In fig. 9, the computer apparatus 900 includes: bus 901, processor 902, memory 903. The processor 902 and the memory 903 may communicate with each other via a bus 901. The memory 903 may have stored therein program instructions. The processor 902 may execute the program instructions to perform the steps of the method of center of pressure acquisition of the previous embodiments.
Bus 901 may be a peripheral platform interconnect standard (Peripheral Component Interconnect, PCI) bus, or an extended industry standard architecture (Extended Industry StandardArchitecture, EISA) bus, among others. The buses may be divided into address buses, data buses, control buses, etc. For ease of illustration, although only one thick line is shown in the figures, only one bus or one type of bus is not shown.
In some embodiments, the processor 902 may be implemented as a central processing unit (Central Processing Unit, CPU), a micro-processing unit (MCU), a System On Chip (System On Chip), or a field programmable logic array (FPGA), or the like. The Memory 903 may include Volatile Memory (RAM) for temporary use of data when running a program, such as random access Memory (RandomAccess Memory).
The Memory 903 may also include a non-volatile Memory (non-volatile Memory) for data storage, such as Read-Only Memory (ROM), flash Memory, hard Disk Drive (HDD) or Solid State Disk (SSD).
In some embodiments, the computer device 900 may also include a communicator 904. The communicator 904 is configured to communicate with the outside. In particular examples, the communicator 904 may include one or a set of wired and/or wireless communication circuit modules. For example, the communicator 904 may include one or more of a wired network card, a USB module, a serial interface module, and the like, for example. The wireless communication protocol followed by the wireless communication module includes: such as one or more of near field wireless communication (Nearfield communication, NFC) technology, infrared (IR) technology, global system for mobile communications (Global System for Mobile communications, GSM), general packet radio service (General Packet Radio Service, GPRS), code Division multiple access (Code Division MultipleAccess, CDMA), wideband Code Division multiple access (Wideband Code Division multiple access, WCDMA), time Division multiple access (Time-Division Code Division MultipleAccess, TD-SCDMA), long term evolution (Long Term Evolution, LTE), blueTooth (BT), global navigation satellite system (Global Navigation Satellite System, GNSS), etc.
Embodiments of the present disclosure may also provide a computer readable storage medium storing program instructions that when executed implement the steps in the pressure center acquisition method in the previous embodiments.
That is, the steps of the method in the above-described embodiments are implemented as software or computer code storable in a recording medium such as a CD ROM, RAM, floppy disk, hard disk, or magneto-optical disk, or as computer code originally stored in a remote recording medium or a non-transitory machine-readable medium and to be stored in a local recording medium downloaded through a network, so that the method represented herein may be processed by such software stored on a recording medium using a general-purpose computer, a special-purpose processor, or programmable or dedicated hardware (such as an ASIC or FPGA).
In summary, in the embodiments of the present disclosure, a rehabilitation training assistance device, a method, a device, and a medium for acquiring a center of pressure are provided, where the device includes: a stand unit comprising: the device comprises a first bearing platform for standing and a pair of first armrests arranged on two sides of the first bearing platform; the seat unit, with the adjacent intercommunication setting of standing position unit includes: the device comprises a second bearing platform for sitting and a pair of second armrests arranged on two sides of the second bearing platform; the first bearing platform, the first handrail, the second bearing platform and the second handrail are all provided with pressure sensor groups; each pressure sensor group is in communication connection with the outside to output pressure signals, and the pressure signals of each pressure sensor group are used for respectively acquiring local pressures born by the first bearing platform, the first handrail, the second bearing platform and the second handrail and position information of local pressure centers, acquiring global pressures at global pressure centers based on the local pressures of the local pressure centers, and acquiring the position information of the global pressure centers based on the position information of the local pressure centers and the global pressures. In the scheme of the disclosure, the pressure sensor group is also arranged on the armrest in the rehabilitation training auxiliary device so as to introduce the pressure signal of the armrest into the calculation of the global pressure center, and the pressure sensor group is closer to the actual situation so as to obtain the accurate global pressure center of the user in various postures and posture change processes.
The above embodiments are merely illustrative of the principles of the present disclosure and its efficacy, and are not intended to limit the disclosure. Modifications and variations may be made to the above-described embodiments by those of ordinary skill in the art without departing from the spirit and scope of the present disclosure. Accordingly, it is intended that all equivalent modifications and variations which a person having ordinary skill in the art would accomplish without departing from the spirit and technical spirit of the present disclosure be covered by the claims of the present disclosure.