Patent Description:
For some of current unmanned apparatuses, driving information required by the unmanned apparatuses is obtained through the fusion of detection information. The accuracy of the driving information is closely related to the accuracy of the fusion of detection information provided by a plurality of sensors. Therefore, how to improve the fusion accuracy of the fusion of the detection information, in order to improve the accuracy of the driving information has become an urgent technical problem to be solved by technicians in this field. <NPL> discloses an approach to enable synchronization and accurate timestamping of hardware trigger able sensors in multi-sensor perception systems. Further <NPL>) discloses an NTP client is to prepare a request packet and add a time stamp of its own system time immediately before the packet is sent to the server, wait for the reply packet from the server, and get another time stamp of its own system time as soon as the packet arrives, evaluate the <NUM> time stamps associated with the reply packet to estimate the packet delay and determine its own time offset from the server, and adjust its own system time so that the time offset is minimized. From <CIT> a sensor synchronization system for an autonomous vehicle is known. Upon initializing a master clock on a master processing node for a sensor apparatus of the autonomous vehicle, the system determines whether an external timing signal is available. If the signal is not available, the system sets the master clock using a local timing signal from a low-power clock on the autonomous vehicle. Based on a clock cycle of the master clock, the system propagates timestamp messages to the sensors of the sensor apparatus, receives sensor data, and formats the sensor data based on the timestamp messages.

The invention is defined in the independent claims, whereas advantageous embodiments are set out in the dependent claims. The present disclosure provides a multi-sensor fusion system and an autonomous mobile electronic apparatus to solve the deficiencies in the related art.

According to a first aspect of the present disclosure, a multi-sensor fusion system is provided, and includes:.

Optionally, the plurality of depth camera modules includes a main camera and at least one auxiliary camera; the main camera includes the trigger signal generation module and the trigger signal output; and
each auxiliary camera includes a trigger signal input, and the trigger signal input is configured to receive the trigger signal output by the trigger signal output.

Optionally, each main camera includes a depth camera and a red-green-blue (RGB) camera; the trigger signal generation module further includes a pulse signal input, and the pulse signal input is connected to the pulse signal output; and
the trigger signal output includes:.

Optionally, the processor includes a first input and a serial input port, the serial input port is configured to be connected to the serial output port of the GPS positioning module to receive a serial port signal output by the serial output port, and the first input is connected to the pulse signal output to receive the pulse signal output by the pulse signal output.

Optionally, the processor includes a calculation module, and the calculation module is configured to calculate the current UTC time based on a sum of the obtained UTC time and a difference between the second local time and the first local time.

Optionally, the processor is configured to update the second local time when a difference between the second local time and the current UTC time is greater than a preset threshold.

Optionally, the trigger module includes a GPS positioning module, and the GPS positioning module is configured to update local time of the depth camera modules, and processors of the depth camera modules record a timestamp of obtained image information according to the updated local time; and
the multi-sensor fusion system further includes:
a host in communication connection with each depth camera module and configured to receive the image information obtained by the depth camera modules, and fuse the image information according to the timestamp.

Optionally, the multi-sensor fusion system further includes:.

Optionally, the GPS positioning module is in communication connection with the host, and the GPS positioning module is further configured to calculate absolute positioning information of an autonomous mobile apparatus to which the GPS positioning module belongs; and
the host is configured to obtain the absolute positioning information, and to obtain relative positioning information of the autonomous mobile apparatus according to the image information, the absolute positioning information and the relative positioning information being used for planning a motion path of the autonomous mobile apparatus.

According to a second aspect of the present disclosure, an autonomous mobile apparatus is provided, and includes: a multi-sensor fusion system, the multi-sensor fusion system including:.

The technical solution provided by the present disclosure may include the following beneficial effects.

It can be seen from the above that through the technical solutions of the present disclosure, the plurality of depth camera modules in the multi-sensor fusion system may be triggered simultaneously by the trigger module, or one of the depth camera modules outputs a trigger signal to trigger other depth camera modules, such that errors between trigger time of the plurality of depth camera modules may be reduced, which is conductive to subsequent fusion of image information at the same time by the plurality of depth camera modules, and improvement of the fusion accuracy.

It should be understood that the above general descriptions and later detailed descriptions are merely exemplary and illustrative, and cannot limit the present disclosure.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present disclosure and together with the specification serve to explain the principles of the present disclosure.

Exemplary embodiments will be described in detail here, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings indicate the same or similar elements. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present disclosure. Rather, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

The terms used in the present disclosure are merely for the purpose of describing specific embodiments, and not intended to limit the present disclosure. The singular forms "one", "said" and "the" used in the present disclosure are also intended to include the plural form unless the context clearly indicates other meanings. It should also be understood that the term "and/or" as used herein refers to and includes any or all possible combinations of one or more associated listed items.

It should be understood that, although the terms "first", "second", "third", etc. may be used to describe various information in the present disclosure, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining that".

For some of current unmanned apparatuses, it is usually necessary to configure a plurality of sensors of the same type or a plurality of sensors of different types to detect information, and driving information required by the unmanned apparatuses is obtained through the fusion of the detected information. The accuracy of the driving information is closely related to the fusion accuracy of the detection information of the plurality of sensors. Therefore, how to improve the fusion accuracy of detection information to improve the accuracy of driving information has become an urgent technical problem to be solved by technicians in this field.

<FIG> is a structural block diagram of a multi-sensor fusion system according to an exemplary embodiment. <FIG> is a schematic diagram of a connection frame between a trigger module and a first depth camera module <NUM> according to an exemplary embodiment. As shown in <FIG> and <FIG>, the multi-sensor fusion system includes a trigger module <NUM>, a first depth camera module <NUM>, and a second depth camera module <NUM>. The trigger module <NUM> may include a pulse signal output <NUM>, and the pulse signal output <NUM> may be used to output a pulse signal generated by a GPS (global positioning system) positioning module. The first depth camera module <NUM> may include a trigger signal generation module <NUM> and a trigger signal output <NUM>. The trigger signal generation module <NUM> may be connected to the pulse signal output <NUM>, such that the trigger signal generation module <NUM> may be used to generate a trigger signal according to the pulse signal output by the pulse signal output terminal <NUM>. The trigger signal output <NUM> may be connected to the trigger signal generation module <NUM>, such that the trigger signal output <NUM> may output a received trigger signal. The pulse signal output <NUM> may include a pulse per second (PPS) pulse signal output, and correspondingly, the pulse signal may include a PPS pulse signal.

Still as shown in <FIG>, the trigger signal output from the trigger signal output <NUM> may be output to the second depth camera module <NUM>, and after receiving the trigger signal, the second depth camera module <NUM> may perform an exposure operation according to the received trigger signal to obtain corresponding image information. Similarly, when a trigger signal is generated and transmitted to a camera included in the first depth camera module <NUM>, the camera may be triggered to perform an exposure operation to obtain corresponding image information.

In the embodiment shown in <FIG>, the multi-sensor fusion system includes a single first depth camera module <NUM> and a single second depth camera module <NUM> as an example for description. In fact, in other embodiments, the multi-sensor fusion system may also include a plurality of first depth camera modules <NUM> and a single second depth camera module <NUM>, or the multi-sensor fusion system may also include a single first depth camera module <NUM> and a plurality of second depth camera modules <NUM>, or the multi-sensor fusion system may also include a plurality of first depth camera modules <NUM> and a plurality of second depth camera modules <NUM>. When the multi-sensor fusion system includes a plurality of first depth camera modules <NUM>, any second depth camera module <NUM> may be triggered by a trigger signal sent by any first depth camera module <NUM> among the plurality of first depth camera modules <NUM>. In some other optional embodiments, the multi-sensor fusion system may also include only a plurality of first depth camera modules <NUM>, and the trigger signal generation module <NUM> included in each first depth camera module <NUM> may generate a trigger signal for triggering based on the received pulse signal, which may be specifically designed as needed, and is not limited in the present disclosure.

It can be seen from the above embodiments that through the technical solutions of the present disclosure, the plurality of depth camera modules in the multi-sensor fusion system may be triggered simultaneously by the trigger module <NUM>, or one of the depth camera modules outputs a trigger signal to trigger other depth camera modules, such that errors between trigger time of the plurality of depth camera modules may be reduced, which is conductive to subsequent fusion of image information at the same time by the plurality of depth camera modules, and improvement of the fusion accuracy.

For a multi-sensor fusion system including a single first depth camera module <NUM> and a single second depth camera module <NUM>, or, a single first depth camera module <NUM> and a plurality of second depth camera modules <NUM>, the first depth camera module <NUM> may be determined as a main camera, and the single or the plurality of second depth camera modules <NUM> may be determined as auxiliary cameras. Still as shown in <FIG> and <FIG>, the first depth camera module <NUM> may include the trigger signal generation module <NUM> and the trigger signal output <NUM> in the above embodiment, and the second depth camera module <NUM> may include a trigger signal input <NUM>. The signal input <NUM> may be connected to the trigger signal output <NUM> of the first depth camera module <NUM>, such that the second depth camera module <NUM> may receive the trigger signal output by the trigger signal output <NUM> via the trigger signal input <NUM>. On this basis, it may be avoided to provide a trigger signal generation module <NUM> and a trigger signal output <NUM> in the second depth camera module <NUM>, which is beneficial to simplifying the structure of the second depth camera module <NUM> and reducing errors of trigger time.

In each of the above embodiments, each first depth camera module <NUM> may include a depth camera <NUM> and a red-green-blue (RGB) camera <NUM>. Similarly, each second depth camera module <NUM> may also include a single or a plurality of cameraes, and the cameraes may include one or more of a depth camera, an RGB camera, a wide-angle camera, or a telephoto camera, etc., which is not limited in the present disclosure. The trigger signal generation module <NUM> may further include a pulse signal input <NUM>, and the pulse signal input <NUM> may be connected to the pulse signal output <NUM>. The trigger signal output <NUM> may include a first output <NUM> and a second output <NUM>. The first output <NUM> may be used to output the trigger signal generated by the trigger signal generation module <NUM> to the depth camera <NUM> and the RGB camera <NUM> of the first depth camera module <NUM>. The second output <NUM> may be used to output the trigger signal generated by the trigger signal generation module <NUM> to the camera of the second depth camera module <NUM>. Thus, errors between the trigger time of a plurality of cameraes included in the same depth camera module may be reduced, and at the same time, errors between the trigger time of a plurality of cameraes included in different depth camera modules may also be reduced. The trigger signal output <NUM> and the trigger signal generation module <NUM> may be integrated into one integrated module, or may be two separate modules, which is not limited in the present disclosure.

Optionally, the trigger signal may include a synchronous frequency multiplied pulse signal. Specifically, the trigger signal generation module <NUM> may generate, based on the received pulse signal, a synchronous frequency multiplied pulse signal corresponding to the pulse signal, for example, a synchronous high-frequency signal of <NUM> or <NUM>. The trigger signal generation module <NUM> may be a field programmable gate array (FPGA) module, or may be any other circuit module capable of generating the synchronous frequency multiplied pulse signal corresponding to the signal, which is not limited in the present disclosure. Compared with other technical solutions in which a first rising edge is used as the trigger time when the main camera is automatically triggered, the technical solution that the depth camera <NUM> and the RGB camera <NUM> are triggered at the same time by the synchronous frequency multiplied pulse signal may control which rising edge or falling edge of the synchronous frequency multiplied pulse signal is received to trigger the depth camera <NUM>, the RGB camera <NUM> and the camera of the second depth camera module <NUM>, and phase control is achieved.

Further, in order to improve the fusion accuracy of the plurality of depth camera modules, still as shown in <FIG> and <FIG>, taking the first depth camera module <NUM> as an example, the first depth camera module <NUM> may further include a processor <NUM>. The processor <NUM> may include a first input <NUM> and a serial input port <NUM>. The trigger module <NUM> may include a GPS positioning module, and the GPS positioning module may include a serial output port <NUM>. The serial input port <NUM> is to be connected to the serial output port <NUM> of the GPS positioning module to receive a serial signal output by the serial output <NUM>. The first input <NUM> is connected to the pulse signal output <NUM> to receive the pulse signal output by the pulse signal output <NUM>.

The processor <NUM> may record first local time when a target edge of the pulse signal is received, obtain a universal time coordinated (UTC) time from the received serial signal when the target edge of the pulse signal is received, record a second local time when the UTC time is obtained, determine current UTC time corresponding to the second local time according to the first local time, the second local time and the obtained UTC time, and then update local time of the processor <NUM> according to the current UTC time. Specifically, the current UTC time is determined as a new second local time, such that the local time of the processor <NUM> may be aligned with the UTC time. It can be understood that the GPS positioning module may obtain a standard time signal from a GPS satellite, and the local time of the processor <NUM> is further updated according to the standard time signal via interaction between the GPS positioning module and the processor <NUM>. The processor <NUM> may also receive the image information obtained by the depth camera <NUM> and the RGB camera <NUM>, and record timestamps of the image information obtained by the depth camera <NUM> and the RGB camera <NUM> according to the updated local time, so as to reduce or eliminate the deviation between the timestamps and the standard time signal. Similarly, each second depth camera module <NUM> may also include a processor, and local time of the processor of the second depth camera module <NUM> may also be updated via the GPS positioning module. For details, please refer to the embodiment of the GPS positioning module updating the local time of the processor <NUM> of the first depth camera module <NUM>. The processor of the second depth camera module <NUM> may also record a timestamp of received image information according to the updated local time, so as to reduce a timestamp error caused by respective local clock errors of the first depth camera module <NUM> and the second depth camera module <NUM>, which is beneficial to realizing time alignment of the depth camera modules via the standard time signal, facilitates fusion of data of the depth camera modules and other sensors, and reduces or eliminates the deviation between the local time of the processor <NUM> and the UTC time compared with a solution of timing based on a local clock of the processor.

The processor <NUM> may generate a first interrupt signal via the first input <NUM> when the target edge of the pulse signal is received, and the processor <NUM> may obtain the accurate local time when the target edge occurs by recording the time of the first interrupt signal, that is, the first local time is obtained, such that the reliability of the first local time may be effectively guaranteed. Regarding how the processor <NUM> records a timestamp, when the trigger signal is the synchronous frequency multiplied pulse signal, the synchronous frequency multiplied pulse signal is suppled to a second input <NUM> of the processor <NUM>, and when a trigger edge (rising edge or falling edge) of the synchronous frequency multiplied pulse signal is received, a second interrupt signal is generated, and local time corresponding to the second interrupt signal is read, and recorded as a timestamp of image information based on the local time. Similarly, the manner in which the processor of the second depth camera module <NUM> records a timestamp of image information may by understood by reference to the above-described embodiment, and the description will not be repeated here.

The serial signal may include GPRMC data or GPGGA data output by the GPS positioning module. The GPS positioning module may output one GPRMC datum or GPGGA datum after each pulse signal is output. The processor <NUM> may obtain the UTC time of the target edge by analyzing the GPRMC data or GPGGA data. The target edge may include a rising edge or a falling edge of the pulse signal. When the target edge is a rising edge, the processor <NUM> may obtain UTC time corresponding to the rising edge by analyzing the GPRMC data or the GPGGA data. When the target edge is a falling edge, the processor <NUM> may obtain the UTC time corresponding to the falling edge by analyzing the GPRMC data or the GPGGA data. The GPGGA data are a GPS data output format statement, and usually include <NUM> fields: sentence tag, world time, latitude, latitude hemisphere, longitude, longitude hemisphere, positioning quality indicator, number of satellites used, horizontal precision factor, ellipsoid height, altitude unit, geoid height anomaly difference, height unit, differential GPS data period, differential reference base station label, and checksum end marker, separated by commas.

In the above embodiment, the processor <NUM> may further include a calculation module. It is assumed that the first local time is T1, the UTC time is T2, the second local time is T3, and the current UTC time needing to be determined by the processor <NUM> and corresponding to the second local time T3 is T4. In some embodiments, a difference between the first local time T1 and the second local time T3 recorded based on non-updated local time of the processor <NUM> may be determined as a difference between the UTC time T2 and the current UTC time T4 corresponding to the second local time T3. Thus, the calculation module may calculate the current UTC time T4 based on a sum of the UTC time T2 and the difference between the second local time T3 and the first local time T1, namely, T4=T2+(T3-T1). In other embodiments, since there may be errors between the local time of the processor <NUM> and the UTC time before updating, the difference between the first local time T1 and the second local time T3 may be calibrated first, and then the current UTC time T4 is calculated by adding the difference and the UTC time T2. A calibration method may be the difference between the first local time T1 and the second local time T3 multiplied by a weight, or the difference between the first local time T1 and the second local time T3 minus or plus a calibration value obtained based on experiments, which is not limited in the present disclosure.

Further, the GPS positioning module continuously sends pulse signals to the processor <NUM> at a certain frequency, while in fact, in some cases, when the error of the local time of the processor <NUM> is within an allowable range, the local time may not be updated, thus reducing the waste of resources of the processor <NUM>. Thus, the processor <NUM> may consider that the error of the current local time of the processor <NUM> exceeds the allowable range when a difference between the second local time T3 and the current UTC time T4 is greater than a preset threshold, and in that case update the local time according to the current UTC time T4.

As shown in <FIG>, the multi-sensor fusion system may further include a host <NUM>. The host <NUM> may be in communication connection with the first depth camera module <NUM> and the second depth camera module <NUM> respectively via, for example, a USB data line according to the embodiment provided by the present disclosure, or via wireless communication according to other embodiments. The host <NUM> is configured to receive the image information obtained by the first depth camera module <NUM> and the second depth camera module <NUM>, and fuse the image information according to timestamps recorded according to the updated local time of the first depth camera module <NUM> and the second depth camera module <NUM>. The implementation of the first depth camera module <NUM> recording the timestamp of the image information and the implementation of the second depth camera module <NUM> recording the timestamp of the image information may be understood by reference to the above-described embodiment. On this basis, by updating time via the GPS positioning module, the local time of the first depth camera module <NUM> and the second depth camera module <NUM> may be aligned with the world time to reduce fusion errors of different depth camera modules caused by time errors of the first depth camera module <NUM> and the second depth camera module <NUM>. The specific implementation of the GPS positioning module updating the local time of the first depth camera module <NUM> and the second depth camera module <NUM> may be understood by reference to the above-described embodiment, which description will not be repeated here.

Still as shown in <FIG>, the GPS positioning module may also be in communication connection with the host <NUM> directly or indirectly via other communication elements. Due to the positioning function of the GPS positioning module, the GPS positioning module may also be used to position absolute positioning information of an autonomous mobile apparatus to which the GPS positioning module belongs, where the absolute positioning information is relative to the earth coordinate system. The host is configured to obtain the absolute positioning information, and obtain relative positioning information of the autonomous mobile apparatus according to the image information. The relative positioning information may be based on any reference point in the traveling process of the autonomous mobile apparatus, and specifically, the relative positioning information may be obtained by adopting the Simultaneous Localization and Mapping, SLAM fusion algorithm.

The absolute positioning information and the relative positioning information are used for planning a motion path of the autonomous mobile apparatus. For example, in some places or areas with weak GPS signals, the motion path may be planned via the relative positioning information, and in some places or areas with good GPS signals, the motion path may be planned via the absolute positioning information, thus improving the motion accuracy. At the same time, the absolute positioning information may also be used for correcting errors of the relative positioning information. For example, a distance between a reference point and a current position point may be obtained by comparing absolute positioning information of the reference point with absolute positioning information of the current position point, so as to correct the relative positioning information. The positioning information obtained by the GPS positioning module may be output via the serial output port <NUM>, and then sent to the host <NUM> via a serial to USB module of the fusion system.

In other optional embodiments, still as shown in <FIG>, the multi-sensor fusion system may further include a Light Detection and Ranging, LIDAR device <NUM>. The LIDAR device <NUM> may be in communication connection with the GPS positioning module and the host <NUM> respectively directly or indirectly via other communication elements, which is not limited in the present disclosure. Specifically, the LIDAR device <NUM> may be connected to the pulse signal output <NUM> and the serial output port <NUM> of the GPS positioning module respectively, such that local time of the lidar device <NUM> may be updated by using the GPS positioning module. An updating method may refer to the above embodiment of the GPS positioning module updating the local time of the first depth camera module <NUM>, which will not be repeated here. Moreover, the LIDAR device <NUM> may also be triggered according to the received pulse signal output by the pulse signal output <NUM> to obtain distance information and record a timestamp of the obtained distance information according to the updated local time. The host <NUM> obtains the distance information and the timestamp of the distance information due to communication connection between the LIDAR devices <NUM>, may also receive the image information of the first depth camera module <NUM> and the second depth camera module <NUM> and the timestamps of the image information, and then may fuse the distance information and the image information according to the timestamps, thus improving the content richness of a fusion image. The fusion accuracy may be improved by updating time via the GPS positioning module.

It should be noted that the embodiment shown in <FIG> is only illustrative, and in other embodiments, the multi-sensor fusion system may also include other sensors, such as a microphone module or an inertial measurement unit, IMU sensor, which are not limited by the present disclosure. There may be one or more sensors of each type, which are not limited by the present disclosure.

Based on the technical solutions of the present disclosure, an autonomous mobile apparatus is further provided. The autonomous mobile apparatus may include the multi-sensor fusion system according to any one of the above embodiments. The autonomous mobile apparatus may include an autonomous vehicle or an unmanned aerial vehicle, etc., which is not limited by the present disclosure.

Claim 1:
A multi-sensor fusion system, comprising:
a trigger module (<NUM>) comprising a pulse signal output (<NUM>) and a global positioning system, GPS, positioning module, the pulse signal output (<NUM>) being used to output a pulse signal, the GPS positioning module comprises a serial output port (<NUM>); and
a plurality of depth camera modules (<NUM>; <NUM>), wherein one depth camera module (<NUM>) of the plurality of depth camera modules comprises a trigger signal generation module (<NUM>) and a trigger signal output (<NUM>), the trigger signal generation module (<NUM>) being used to generate a trigger signal according to the pulse signal, and the trigger signal output (<NUM>) being connected to the trigger signal generation module (<NUM>), and used to output the trigger signal, the depth camera modules (<NUM>, <NUM>) each comprise a processor (<NUM>), the processor (<NUM>) is used to receive a serial signal output by the GPS positioning module, and receive the pulse signal output by the pulse signal output (<NUM>); wherein
the trigger signal is used to trigger said one depth camera module (<NUM>) to perform an exposure operation, and the other depth camera modules (<NUM>) of the plurality of depth camera modules to perform exposure operations according to the received trigger signal output by the trigger signal output (<NUM>);
wherein:
the processor (<NUM>) is configured to record a first local time when a target edge of the pulse signal is received, obtain a universal time coordinated, UTC time from the serial signal when the target edge is received, and record a second local time when the UTC time is obtained, so as to determine a current UTC time corresponding to the second local time according to the first local time, the second local time and the obtained UTC time, and update the second local time according to the current UTC time, wherein the target edge comprises at least one of a rising edge or a falling edge of the pulse signal, and wherein the local time is the time of a local clock of the processor (<NUM>).