The present disclosure relates to a field of household appliance detecting techniques, and more particularly to a method and a device for detecting a moving distance, and a computer-readable storage medium.
Movement of a robot cleaner is realized by a moving wheel arranged in the robot cleaner. An accuracy of detecting a moving distance of the robot cleaner is an important element required to control a posture, estimate a position and draw a working map of the robot cleaner. A problem of low accuracy of detecting the moving distance of the moving wheel is currently needed to be solved. The moving wheel of the existing robot cleaner is generally equipped with a wheel encoder configured to detect the rotation amount of the motor connected to the moving wheel and determine the moving distance of the robot cleaner according to the rotation amount, thus providing basic information required for positioning the robot cleaner and producing the map.
In the existing methods, in order to improve the accuracy of the moving distance, the number of Hall sensors is generally increased and 2{circumflex over ( )}K phases may be distinguished by K Hall sensors to achieve a high-accuracy measurement. However, it is difficult to choose spatial positions for the Hall sensors and the price of the Hall sensor is relatively high, problems of difficulties in improving the detection accuracy of the moving distance and high cost still exist.
In order to solve the problems existing in the related art, embodiments of the present disclosure provide a method and a device for detecting a moving distance, and a computer-readable storage medium.
Technical solutions of the present disclosure are realized as follows.
Embodiments of the present disclosure provide a method for detecting a moving distance, applied to an automatic cleaning device including a moving wheel, in which the moving wheel includes a disk magnet disposed at a pivot center of the moving wheel and configured to rotate along with the moving wheel; the disk magnet includes at least one set of magnets, each set of magnets having two corresponding poles; the moving wheel further includes a Hall sensor configured to monitor a change amount of a magnetic field strength of each set of magnets in the disk magnet, and a movement trajectory of the Hall sensor is parallel to and synchronized with a movement trajectory of the pivot center of the moving wheel; the method includes:
monitoring the change amount of the magnetic field strength of each set of magnets in the disk magnet, and outputting N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets, in which a value of N is associated with a rotation arc of the moving wheel, and N is a positive number,
determining a rotation arc of the disk magnet according to the N pulse waveforms, and
determining a moving distance of the moving wheel according to the rotation arc of the disk magnet.
In an embodiment of the present disclosure, determining a rotation arc of the disk magnet according to the N pulse waveforms includes:
determining a rotation direction of the moving wheel according to a voltage value corresponding to the N pulse waveforms, in which the rotation direction includes a forward rotation direction and a reverse rotation direction;
determining a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction;
adding the first rotation arc to the second rotation arc to obtain a result and taking the result as the rotation arc of the moving wheel.
In an embodiment of the present disclosure, determining a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction includes:
inquiring a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms and determining the first rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the forward rotation direction and the second rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the reverse rotation direction in the N pulse waveforms.
In an embodiment of the present disclosure, before inquiring a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms, the method further includes:
determining the number of sets of the magnets, and determining the correspondence relationship between the pulse waveforms and the rotation arcs according to the number of sets of the magnets.
In an embodiment of the present disclosure, determining a moving distance of the moving wheel according to the rotation arc of the disk magnet includes:
determining a radius of the moving wheel, and determining the moving distance of the moving wheel according to the radius of the moving wheel and the rotation arc of the disk magnet.
Embodiments of the present disclosure further provide an apparatus for detecting a moving distance, applied to an automatic cleaning device including a moving wheel, in which the moving wheel includes a disk magnet disposed at a pivot center of the moving wheel and configured to rotate along with the moving wheel; the disk magnet includes at least one set of magnets, each set of magnets having two corresponding poles; the moving wheel further includes a Hall sensor configured to monitor a change amount of a magnetic field strength of each set of magnets in the disk magnet, and a movement trajectory of the Hall sensor is parallel to and synchronized with a movement trajectory of the pivot center of the moving wheel; the apparatus includes a first determining module and a second determining module, in which
the first determining module is configured to monitor the change amount of the magnetic field strength of each set of magnets in the disk magnet, and output N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets, in which a value of N is associated with a rotation arc of the moving wheel, and N is a positive number,
the second determining module is configured to determine a rotation arc of the disk magnet according to the N pulse waveforms, and determine a moving distance of the moving wheel according to the rotation arc of the disk magnet.
In an embodiment of the present disclosure, the second determining module is specifically configured to determine a rotation direction of the moving wheel according to a voltage value corresponding to the N pulse waveforms, in which the rotation direction includes a forward rotation direction and a reverse rotation direction; determine a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction; add the first rotation arc to the second rotation arc to obtain a result and take the result as the rotation arc of the moving wheel.
In an embodiment of the present disclosure, the second determining module is specifically configured to inquire a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms and determine the first rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the forward rotation direction and the second rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the reverse rotation direction in the N pulse waveforms.
In an embodiment of the present disclosure, the second determining module is further configured to determine the number of sets of the magnets and determine the correspondence relationship between the pulse waveforms and the rotation arcs according to the number of sets of the magnets.
In an embodiment of the present disclosure, the second determining module is specifically configured to determine a radius of the moving wheel, and determine the moving distance of the moving wheel according to the radius of the moving wheel and the rotation arc of the disk magnet.
Embodiments of the present disclosure further provide a device for detecting a moving distance, including a processor; a memory having stored therein computer programs executable on the processor, in which when the computer programs are executed by the processor, the processor is configured to perform a method described above.
Embodiments of the present disclosure further provide a computer-readable storage medium having stored therein computer programs that, when executed by a processor, cause the processor to perform a method described above.
The method and device for detecting the moving distrance and the computer-readable storage medium provided by embodiments of the present disclosure are applied to the automatic cleaning device including the moving wheel. The moving wheel includes a disk magnet disposed at a pivot center of the moving wheel and configured to rotate along with the moving wheel; the disk magnet includes at least one set of magnets, each set of magnets having two corresponding poles; the moving wheel further includes a Hall sensor configured to monitor a change amount of a magnetic field strength of each set of magnets in the disk magnet, and a movement trajectory of the Hall sensor is parallel to and synchronized with a movement trajectory of the pivot center of the moving wheel. The technical solution of the present disclosure includes: monitoring the change amount of the magnetic field strength of each set of magnets in the disk magnet, and outputting N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets, in which a value of N is associated with a rotation arc of the moving wheel, and N is a positive number, determining a rotation arc of the disk magnet according to the N pulse waveforms, and determining a moving distance of the moving wheel according to the rotation arc of the disk magnet. In the solution according to embodiments of the present disclosure, the moving distance of the moving wheel can be detected accurately without increasing the number of the Hall sensors or the magnets.
In embodiments of the present disclosure, a change amount of a magnetic field strength of each set of magnets in a disk magnet is monitored, and N pulse waveforms are output according to the change amount of the magnetic field strength of each set of magnets, in which a value of N is associated with a rotation arc of a moving wheel, and N is a positive number. A rotation arc of the disk magnet is determined according to the N pulse waveforms. A moving distance of the moving wheel is determined according to the rotation arc of the disk magnet.
Firstly, a method of detecting a moving distance with a wheel encoder is described below.
The moving wheel of a robot cleaner is typically equipped with a motor, a disk magnet and a Hall sensor. Specifically, the motor is configured to drive the moving wheel to rotate, and the disk magnet and the Hall sensor are configured to detect a rotation amount of the moving wheel. The disk magnet generally includes from 12 poles to 36 poles, and the rotation amount is detected by using two or more Hall sensors in view of accuracy. The detecting method may include following steps. A magnetic field of a south/north (S/N) pole in a plurality of magnets is detected and a pulse is output. A single rotation motion may be a 360-degree rotation being divided into 6 to 18 (i.e., dividing 12 by 2 to dividing 36 by 2) parts in an accuracy in view of the pulse. Two Hall sensors are used and 4 phases are distinguished, such that the 360-degree rotation may be divided in 24 to 72 (i.e., multiplying 6 by 4 to multiplying 18 by 4) parts in an accuracy in view of the phase, that is, one phase corresponds to a rotation movement of 15° to 5°.
In order to improve the detection accuracy, the number of poles of the disk magnet can be increased or multiple Hall sensors can be added to further refine the phase, thus improving the detection accuracy. However, in the case that the number of poles of the disk magnet is increased, a size of the disk magnet will be enlarged since the magnitude of the detected magnetic force is proportional to the volume of m/2 (m is the number of poles) magnets. In the case that multiple Hall sensors are adopted, it is difficult to distribute the multiple Hall sensors considering the position of the S/N poles of the disk magnet. Moreover, in a mass production, actual lengths of printed circuit boards (PCBs) are different, and thus products may have different phases, which are difficult to become identical. In addition, the price of the Hall sensor is relatively high.
With reference to
As described above, it is difficult for the existing robot cleaner to identify an accurate 90° phase difference. Actions of the four phases are different, and the moving distance detected by each section is stepped, such that the moving distance cannot be accurately detected.
The moving wheel further includes a Hall sensor configured to monitor a change amount of a magnetic field strength of each set of magnets in the disk magnet, and a movement trajectory of the Hall sensor is parallel to and synchronized with a movement trajectory of the pivot center of the moving wheel.
As shown in
At step 301, the change amount of the magnetic field strength of each set of magnets in the disk magnet is monitored, and N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets are output, in which a value of N is associated with a rotation arc of the moving wheel, and N is a positive number.
The pulse waveform represents a voltage value corresponding to the magnetic field strength herein.
In some embodiments, the moving wheel of the automatic cleaning device includes at least one Hall sensor.
In the step 301, it is included that the change amount of the magnetic field strength of each set of magnets in the disk magnet is monitored by the Hall sensor, and N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets are output.
The automatic cleaning device may further include a processor configured to detect the moving distance of the automatic cleaning device.
In some embodiments, the step 301 may further include following steps.
The change amount of the magnetic field strength of each set of magnets in the disk magnet is monitored by the Hall sensor. The processor receives the change amount of the magnetic field strength and performs an analog-to-digital conversion on the change amount of the magnetic field strength, thus acquiring N pulse waveforms representing the change amount of the magnetic field strength.
In some embodiments, the detected magnetic field strength may be sent to the processor from the Hall sensor and the processor performs the analog-to-digital (AD) conversion on the magnetic field strength to acquire a voltage waveform representing the change of the magnetic field strength. The voltage waveform presents in a form of pulse waveform (specifically, a sine waveform).
The processor may be realized by a central processing unit (CPU), a digital signal processor (DSP), a micro control unit (MCU) or a field-programmable gate array (FPGA).
At step 302, a rotation arc of the disk magnet is determined according to the N pulse waveforms.
In some embodiments, determining a rotation arc of the disk magnet according to the N pulse waveforms includes:
determining a rotation direction of the moving wheel according to a voltage value corresponding to the N pulse waveforms, in which the rotation direction includes a forward rotation direction and a reverse rotation direction;
determining a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction by the processor;
adding the first rotation arc to the second rotation arc to obtain a result and taking the result as the rotation arc of the moving wheel.
In some embodiments, the forward rotation and the reverse rotation may happen when the moving wheel rotates, and thus the rotation direction of the moving wheel should be determined. Herein, two manners are described for determining the rotation direction of the moving wheel.
The first manner: a driving instruction sent by the processor to control the direction of the moving wheel is received, and the rotation direction of the moving wheel is determined according to the driving instruction.
The second manner: a rotation direction of the moving wheel is determined according to the voltage waveform. In some embodiments, it can be preset by the processor that a positive voltage value indicates a forward rotation and a negative voltage value indicates a reverse rotation, such that the rotation direction of the moving wheel may be determined by the voltages corresponding to the N pulse waveforms.
The processor is further configured to determine a switching point of the forward rotation and the reverse rotation, and the determining method includes following steps. The magnetic field strengths detected by the Hall sensor are sequentially input into the processor. After the digital-to-analog conversion is performed on the magnetic field strengths by the processor, the pulse waveform is acquired. When it is determined by the processor according to the pulse waveform that a product multiplying a current voltage value by a voltage value one second before is less than or equal to zero, as shown in formula (1), zero crossing occurs. The zero crossing means a transition from the forward rotation to the reverse rotation or from the reverse rotation to the forward rotation.
in which, f(V(0)=1, at zero crossing, represents a time point, and the Vi represents a detected voltage value.
The pulse waveform is determined according to the rotation direction and the zero crossing point by the processor, thus determining a first rotation arc when the moving wheel rotates in the forward direction and a second rotation arc when the moving wheel rotates in the reverse direction.
In some embodiments, determining a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction includes:
inquiring a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms and determining the first rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the forward rotation direction and the second rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the reverse rotation direction in the N pulse waveforms.
In some embodiments, before inquiring a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms, the method further includes:
determining the number of sets of the magnets, and determining the correspondence relationship between the pulse waveforms and the rotation arcs according to the number of sets of the magnets.
In some embodiments, a disk magnet with M (M is a multiple of 2) poles is disposed on the moving wheel to measure the rotation angle of the moving wheel. When the moving wheel rotates 360°, i.e., one cycle, M/2 complete pulse waveforms are detected by the Hall sensor, that is, a complete pulse waveform equivalents to a rotation angle of 360°/M/2, and the rotation angle of 360°/M/2 is converted into radians (1 radian=180°/π), such that a correspondence relationship between pulse waveforms and rotation arcs may be determined. According to the above description, the correspondence relationship between the pulse waveforms and the rotation arcs meets formula (2) shown as follows.
in which θi represents a rotation arc in radians, i represents a time point, Vi represents a voltage value of the ith second, and A represents a peak value of a sinusoidal waveform.
It should be noted that when it is determined by the processor that the acquired pulse waveform includes X complete sine waveforms,
At step 303, a moving distance of the moving wheel is determined according to the rotation arc of the disk magnet.
In some embodiments, the step 303 includes determining a radius of the moving wheel by the processor, and determining the moving distance of the moving wheel according to the radius of the moving wheel and the rotation arc of the disk magnet.
In some embodiments, the moving distance=R*θi, in which R represents the radius of the moving wheel, and θi represents a rotation arc. Specifically, θi=2*π*angle°/360°, the angle° represents a rotation angle in degrees.
In some embodiments, the output value of the waveform measured by the processor of the first moving wheel, i.e., Enc1, at t=0 is equivalent to A sin 240°, and the output value of the waveform measured by the processor of the second moving wheel, i.e., Enc2, at t=0 is equivalent to A sin 150°. Herein, one sinusoidal waveform is equivalent to a rotation angle of 360°/8/2. According to the sinusoidal waveform of the processor of the first moving wheel, the rotation angle can be calculated as {(360°−240°)+360°*2+90°}/8/2. According to the sinusoidal waveform of the processor of the second moving wheel, the rotation angle can be calculated as {(360°-150°)+360° *2}/8/2. The rotation arc is determined by the rotation angle, and the moving distance of the moving wheel may be determined according to the rotation arc in combination with a radius of the moving wheel. Triangular waves (Angle dist. 1 and Angle dist. 2) in the
It should be noted that, in order to quickly determine the Arcsin value corresponding to an angle, an infinite number of Arcsin values may be stored in the processor in an embodiment of the present disclosure. Specifically, 180 Arcsin values from 0° to 90° with an interval of 0.5° or 90 Arcsin values from 0° to 90° with an interval of 1° are stored in the processor, and other values of corresponding angles can be calculated according to the symmetrical characteristics of the sine function. A way to determine the Arcsin value may be as follows. A part of Arcsin values corresponding to a rotation angle ranged from 0° to 90° are stored, and a measured intermediate value is interpolated by using the stored values and an interpolation filter. During the interpolation realized by using the stored values and the interpolation filter, for a function f (x) with a real variable x, when two or more function values f (xi) (i=1, 2, . . . ) with a certain shape and a certain interval are known, any f (x) in this section can be calculated. Unobserved values can be inferred from the unpredicted function according to the predictions obtained from experiments or observations. In the embodiment, due to expansion of the function, in the neighborhood between the variables x0 and x1, polynomial interpolation may be calculated by an approximate expression function of the function f (x), i.e.,
In some embodiments, the second determining module 602 is specifically configured to determine a rotation direction of the moving wheel according to a voltage value corresponding to the N pulse waveforms, in which the rotation direction includes a forward rotation direction and a reverse rotation direction; determine a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction; add the first rotation arc to the second rotation arc to obtain a result and take the result as the rotation arc of the moving wheel.
In some embodiments, the second determining module 602 is specifically configured to inquire a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms and determine the first rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the forward rotation direction and the second rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the reverse rotation direction in the N pulse waveforms.
In some embodiments, the second determining module 602 is further configured to determine the number of sets of the magnets and determine the correspondence relationship between the pulse waveforms and the rotation arcs according to the number of sets of the magnets.
In some embodiments, the second determining module 602 is specifically configured to determine a radius of the moving wheel, and determine the moving distance of the moving wheel according to the radius of the moving wheel and the rotation arc of the disk magnet.
In order to realize the method according to embodiments of the present disclosure, embodiments of the present disclosure provide a device for detecting a moving distance, applied to an automatic cleaning device. Specifically, as shown in
monitor the change amount of the magnetic field strength of each set of magnets in the disk magnet, and output N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets, in which a value of N is associated with a rotation arc of the moving wheel, and N is a positive number,
determine a rotation arc of the disk magnet according to the N pulse waveforms, and
determine a moving distance of the moving wheel according to the rotation arc of the disk magnet.
In an embodiment of the present disclosure, when the computer programs are executed by the processor 701, the processor 701 is configured to:
determine a rotation direction of the moving wheel according to a voltage value corresponding to the N pulse waveforms, in which the rotation direction includes a forward rotation direction and a reverse rotation direction;
determine a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction;
add the first rotation arc to the second rotation arc to obtain a result and take the result as the rotation arc of the moving wheel.
In an embodiment of the present disclosure, when the computer programs are executed by the processor 701, the processor 701 is configured to inquire a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms and determine the first rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the forward rotation direction and the second rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the reverse rotation direction in the N pulse waveforms.
In an embodiment of the present disclosure, when the computer programs are executed by the processor 701, the processor 701 is configured to determine the number of sets of the magnets and determine the correspondence relationship between the pulse waveforms and the rotation arcs according to the number of sets of the magnets
In an embodiment of the present disclosure, when the computer programs are executed by the processor 701, the processor 701 is configured to determine a radius of the moving wheel, and determine the moving distance of the moving wheel according to the radius of the moving wheel and the rotation arc of the disk magnet.
It should be noted that the device for detecting the moving distance provided in the above embodiments are constituted in the same principle of the method for detecting the moving distance, and the specific implementation process may refer to the method embodiments and thus details are not described here again.
In actual practices, as shown in
The method described in the above embodiments of the present disclosure may be applied to the processor 701 or realized by the processor 701. The processor 701 may be an integrated circuit chip with a signal processing capability. In the implementation process, each step of the method described above may be realized by an integrated logic circuit of the hardware in the processor 701 or an instruction in a form of the software. The processor 701 described above may be a general purpose processor, a digital signal processor (DSP) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components or the like. The processor 701 is configured to perform the methods, steps, and logic blocks disclosed in the embodiments of the present disclosure. The general purpose processor may be a microprocessor or any other conventional processor. The steps of the method disclosed in the embodiment of the present disclosure may be directly realized by the hardware of a decoding processor or a combination of hardware and software modules in the decoding processor. The software module may be in a storage medium, which is provided in a memory 702, and processor 701 reads information stored in the memory 702, in conjunction with the hardware, to perform the steps of the above method.
In an exemplary embodiment, the device 70 for detecting the moving distance may be realized by one or more application specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), general purpose processors, controllers, micro controller units (MCUs), microprocessors, or other electronic components to perform the aforementioned methods.
Specifically, embodiments of the present disclosure provide a computer-readable storage medium having stored therein computer programs that, when executed by a processor, cause the processor to:
monitor the change amount of the magnetic field strength of each set of magnets in the disk magnet, and output N pulse waveforms according to the change amount of the magnetic field strength of each set of magnets, in which a value of N is associated with a rotation arc of the moving wheel, and N is a positive number,
determine a rotation arc of the disk magnet according to the N pulse waveforms, and
determine a moving distance of the moving wheel according to the rotation arc of the disk magnet.
In an embodiment of the present disclosure, when the computer programs are executed by the processor, the processor is configured to:
determine a rotation direction of the moving wheel according to a voltage value corresponding to the N pulse waveforms, in which the rotation direction includes a forward rotation direction and a reverse rotation direction;
determine a first rotation arc when the moving wheel rotates in the forward rotation direction and a second rotation arc when the moving wheel rotates in the reverse rotation direction;
add the first rotation arc to the second rotation arc to obtain a result and take the result as the rotation arc of the moving wheel.
In an embodiment of the present disclosure, when the computer programs are executed by the processor, the processor is configured to inquire a stored correspondence relationship between pulse waveforms and rotation arcs according to the N pulse waveforms and determine the first rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the forward rotation direction and the second rotation arc corresponding to a pulse waveform generated when the moving wheel rotates in the reverse rotation direction in the N pulse waveforms.
In an embodiment of the present disclosure, when the computer programs are executed by the processor, the processor is configured to determine the number of sets of the magnets and determine the correspondence relationship between the pulse waveforms and the rotation arcs according to the number of sets of the magnets
In an embodiment of the present disclosure, when the computer programs are executed by the processor, the processor is configured to determine a radius of the moving wheel, and determine the moving distance of the moving wheel according to the radius of the moving wheel and the rotation arc of the disk magnet.
Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure, and thus should be included in the scope of the present disclosure.
Number | Date | Country | Kind |
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201810490173.4 | May 2018 | CN | national |
This application is a continuation of International Application No. PCT/CN2018/098023, filed on Aug. 1, 2018, which claims a priority to and benefits of Chinese Patent Application Serial No. 201810490173.4, filed with the State Intellectual Property Office of P. R. China on May 21, 2018, the entire content of which is incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/CN2018/098023 | Aug 2018 | US |
Child | 16125794 | US |