WO2021019349A1

WO2021019349A1 - Capturing unit and vehicle control unit

Info

Publication number: WO2021019349A1
Application number: PCT/IB2020/056674
Authority: WO
Inventors: Masashi Adachi
Original assignee: Ricoh Company, Ltd.
Priority date: 2019-07-30
Filing date: 2020-07-16
Publication date: 2021-02-04

Abstract

A capturing unit includes a pair of imaging devices, a circuit board provided with at least two parts related to an operation of the pair of imaging devices, a housing configured to hold the circuit board, a pair of convex portions disposed on the housing across a center between two optical axes of the pair of imaging devices in the housing, the pair of convex portions projecting toward the circuit board, and at least two heat-dissipating members each of which is disposed on one of the pair of convex portions to touch one of the at least two parts and dissipate heat from the one of the at least two parts. In the capturing unit, the pair of convex portions are disposed and shaped to be more line-symmetric across the center between the two optical axes of the pair of imaging devices than the at least two parts.

Description

[DESCRIPTION]

[Title of Invention]

CAPTURING UNIT AND VEHICLE CONTROL UNIT

[Technical Field]

[0001]

Embodiments of the present disclosure relate to a capturing unit and a vehicle control unit. [Background Art]

[0002]

In the related art, so-called stereo cameras are known in the art as a capturing unit that can measure the distance to the position of a target like human eyes. As known in the art, a stereo camera is provided with two monocular cameras. For example, a stereo camera may be configured to work together with a vehicle control unit that controls a vehicle. Due to such a configuration, the distance to an object existing ahead of the vehicle is calculated, and the operation or movement of the vehicle can be controlled based on the calculated distance.

[0003]

The pair of monocular cameras that are provided for a stereo camera are arranged on the same plane in a coplanar manner, and are fixed such that the optical axes of both monocular cameras become parallel to each other. As such a pair of monocular cameras capture the same subject at the same time, a disparity between a pair of images of the subject can be detected, and the distance to the subject can accurately be calculated based on the detected disparity.

[0004]

In order for a stereo camera to calculate distance with a high degree of precision, the focal length of a pair of monocular cameras of the stereo camera needs to be made the same by matching the properties and characteristics of the lenses of these monocular cameras. Moreover, it is important to fix the value of the base-line length that is the distance between the optical axes of a pair of monocular cameras to a design value in a continuous manner. Further, it is important to design the parallelism of the optical axes of the pair of monocular cameras as desired at the time of assembling, and such a parallelism needs to be maintained in a continuous manner.

[0005]

In order to achieve such a configuration, the technologies to arrange multiple heating elements at symmetrical positions across the center between the optical axes of the pair of monocular cameras are known in the art (see, for example, PTL 1). Such technologies were developed for the purpose of preventing the degradation of the stereo camera. Due to such technologies, when the housing is thermally-deformed due to high temperature, such deformation becomes bilaterally symmetrical.

[Citation List]

[Patent Literature]

[0006]

[PTL 1]

International Publication No. WO2017-163584

[Summary of Invention]

[Technical Problem]

[0007]

As known in the art, a stereo camera is provided with a plurality of heating elements that liberate heat of high temperature. For example, a plurality of heating elements that perform image processing or disparity computation, such as an application-specific-integrated-circuits (ASICs) or a field-programmable gate array (FPGA) in addition to a central processing unit (CPU) that serves as a control circuit, are provided for a stereo camera. Such multiple heating elements differ from each other in its type, the installed position on a circuit board, the size, or the like. For this reason, it is very difficult to arrange multiple heating elements at symmetrical positions across the center between the optical axes of a pair of monocular cameras (see, for example, the technologies disclosed in PTL 1).

[Solution to Problem]

[0008]

[Advantageous Effects of Invention]

[0009]

According to one aspect of the present disclosure, when a housing deforms due to changes in temperature, the horizontally-asymmetrical deformation of the housing due to thermal expansion can be prevented.

[Brief Description of Drawings]

[0010]

The accompanying drawings are intended to depict example embodiments of the present invention and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.

[Fig· 1]

FIG. 1 is a schematic exploded perspective view of a stereo camera according to a first embodiment of the present disclosure.

[Fig. 2]

FIG. 2 is a perspective view of a housing of the stereo camera, viewed from the rear side, according to the first embodiment of the present disclosure.

[Fig. 3]

FIG. 3 is a longitudinal A-A sectional view of the stereo camera as illustrated in FIG. 1.

[Fig. 4]

FIG. 4 is a diagram illustrating the relative positions of a pair of receptive-shaped parts, a couple of heating elements, and a heat-dissipating member in the stereo camera as illustrated in FIG. 1

[Fig. 5]

FIG. 5 is a diagram illustrating a schematic configuration of a vehicle control unit according to a second embodiment of the present disclosure.

[Description of Embodiments]

[0011]

A capturing unit and a vehicle control unit according to embodiments of the present disclosure are described below in detail with reference to the accompanying drawings.

[0012]

First Embodiment

[0013]

FIG. 1 is a schematic exploded perspective view of a stereo camera 1 according to a first embodiment of the present disclosure.

[0014]

FIG. 2 is a perspective view of a housing 10 of the stereo camera 1, viewed from the rear side, according to the present embodiment.

[0015] FIG. 3 is a longitudinal A- A’ sectional view of the stereo camera 1 as illustrated in FIG. 1.

[0016]

FIG. 4 is a diagram illustrating the relative positions of a pair of receptive-shaped parts 11, a couple of heating elements, and a heat-dissipating member 40 in the stereo camera 1 as illustrated in FIG. 1, according to the present embodiment.

[0017]

As illustrated in FIG. 1, the stereo camera 1 that serves as a capturing unit includes a housing 10 that serve as an imaging-device holder and holds a pair of imaging devices (monocular cameras) 100, and a circuit board 20 that is fixed to the housing 10.

[0018]

As illustrated in FIG. 2, the housing 10 is provided with a pair of receptive-shaped parts 11 whose shape is equivalent to each other. The pair of receptive-shaped parts 11 project to the side of the circuit board 20, and are arranged in bilateral symmetry. When viewed from the upper side of the housing 10, each one of the pair of receptive-shaped parts 11 is concave shaped. Note also that each one of the pair of receptive-shaped parts 11 may be formed as a single integrated unit with the housing 10 or may be formed or configured separately from the housing 10. Moreover, each one of the pair of receptive-shaped parts 11 is satisfactory as long as it projects to the side of the circuit board 20, and may be formed such that the concave shape is invisible from the outside of the housing 10.

[0019]

The axes in the three-dimensional rectangular coordinate system, which are used to describe the structure or configuration of the stereo camera 1, are defined as follows. As illustrated in FIG. 1, the direction in which the lenses 101 of the pair of imaging devices 100 are aligned is defined as the X-axis. The direction of a normal to the image formed by an image sensor 102 (see FIG. 2) provided for each one of the pair of imaging devices 100 is defined as the Z-axis, and the height direction of the stereo camera 1 orthogonal to both the X-axis and Z-axis is defined as the Y-axis.

[0020]

Each one of the pair of imaging devices 100 includes the lens 101, the image sensor 102, and a sensor board 103. Each one of the lenses 101 is fitted to a hole 10b arranged on the front side of a camera stay 10a of the housing 10 in the X-axis direction. When the lenses 101 are fitted to the camera stay 10a, the distance between the two optical axes Lx of the pair of imaging devices 100 is maintained at a constant distance. Such a distance is referred to as base-line length, and the base-line length is used to calculate the distance to an object. Moreover, in the present embodiment, the optical axes Lx of the lenses 101 are directed to the same direction and are made parallel to the Z-axis.

[0021]

The image sensor 102 is fixed to the rear side of each one of the lenses 101 in the Z-axis direction, and it is configured such that the optical axis Lx of each one of the lenses 101 match the center of the imaging plane of the image sensor 102. The image sensor 102 is an imaging device fixed to the individual sensor board 103, and outputs a signal that relates to an object image formed on the imaging plane through the corresponding one of the lenses 101.

[0022]

In other words, each one of the pair of imaging devices 100 is assembled by fitting the lens 101 to the hole 10b arranged on the front side of the camera stay 10a and fixing the image sensor 102 in line with the optical axis Lx of the lens 101. Due to this configuration, the stereo camera 1 can detect a disparity based on the multiple images captured by the pair of image sensors 102, and can calculate the distance.

[0023]

In order to calculate the distance with precision, the two lenses 101 need to be fixed with a high degree of precision with reference to the base-line length, which is a key element in the present embodiment. In order to achieve such a configuration, the lenses 101 need to be kept at a predetermined position precisely with predetermined posture or attitude. For such purposes, for example, the butt face of the camera stay 10a for the lens 101 is processed with precision, and the butt portion of the lens 101 for the camera stay 10a is processed with precision. Through the camera stay 10a, the hole 10b to which the lens 101 is fitted is processed with precision in terms of, for example, the position and size, and then the lens 101 is fitted to the precisely-processed hole 10b. In order to achieve the matched focal length, which is a key element in the calculation of distance in the present embodiment, the lenses 101 with the same optical properties are used. Also for the image sensors 102 on which the properties and characteristics of the camera depend, the image sensors with the same properties and characteristics are used. However, no limitation is intended thereby, and a plurality of lenses or sensors with different properties and characteristics may be used.

[0024]

In order to calculate the distance to an object with precision, the parallelism between the two optical axes Lx of the pair of lenses 101 needs to be maintained with precision. In order to maintain such a parallelism, again, the butt face of the camera stay 10a for the lens 101 and the butt portion of the lens 101 for the camera stay 10a need to be processed and formed with a high degree of precision. Moreover, in the present embodiment, each one of the holes 10b is precisely processed and formed on the corresponding one of the camera stays 10a.

[0025]

Elements that are related to the operation of the imaging devices 100, such as an arithmetic element or logic element used to control the operation of the imaging devices 100 or calculate the distance based on a disparity between a pair of images or an element used to control the power supply, are arranged on the circuit board 20. As illustrated in FIG. 1, in addition to a central processing unit (CPU) 21 that serves as a control circuit, a processing circuit 22 that performs image processing or disparity computation, such as an application-specific-integrated- circuits (ASICs) and a field-programmable gate array (FPGA), a power supply circuit 23 that supplies operating power to the CPU 21 or the like, are arranged on the circuit board 20. Note also that the circuit board 20 and the imaging devices 100 are coupled to each other through wires. Some of such elements as described above is a heating element that liberates heat of high temperature. The heating elements that are illustrated in FIG. 1 as an example are the CPU 21 and the processing circuit 22.

[0026]

Note also that the heating elements such as the CPU 21 and the processing circuit 22 differ from each other in its type, the installed position on the circuit board 20, the size, or the like.

[0027]

In the following description, it is assumed that the CPU 21 is the only heating element in the stereo camera 1 according to the present embodiment. As a matter of course, no limitation is indicated thereby, and there is no need to limit the heating element to the CPU 21. For example, other elements that are implemented on the circuit board 20, a field-programmable gate array (FPGA), and a power-supply integrated circuit (IC) may also serve as a heating element. When a plurality of heating elements are arranged on the circuit board 20, a plurality of heat-dissipating members 40, as will be described later in detail, may be provided for such a plurality of heating elements.

[0028]

The heating elements dissipate heat to the surrounding area during operation. For example, a heating element such as the CPU 21 may exhibit thermal runaway and does abnormal operation without sufficient heat dissipation. In order to handle such a situation, the heat-dissipating member 40 that enhances heat dissipation is attached to the CPU 21.

[0029]

The heat-dissipating member 40 is made of a material called thermal interface material (TIM). The TIM effectively enhances the thermal conductivity. For example, the TIM may be made up of thermal-conductive grease or a graphite sheet in addition to metal. [0030]

One side of the heat-dissipating member 40 contacts a side of the CPU 21 to absorb the heat, and the other side of the heat-dissipating member 40 contacts the housing 10. The heat- dissipating member 40 and the CPU 21 are bonded together by, for example, a double-sided adhesive tape.

[0031]

The other side of the heat-dissipating member 40 contacts the housing 10 at, for example, the receptive-shaped part 11 as illustrated in FIG. 2. More specifically, as illustrated in FIG. 1 to FIG. 4, there are two pairs of receptive-shaped parts 11 and heat-dissipating members 40, and each one of the heat-dissipating members 40 contacts the corresponding one of the receptive shaped parts 11. Each one of the heat-dissipating members 40 is arranged on the corresponding one of the pair of receptive-shaped parts 11 that project to the side of the circuit board 20, and contacts two kinds of heating elements (e.g., the CPU 21 and the processing circuit 22) to dissipate the heat radiated therefrom.

[0032]

In other words, the pair of receptive- shaped parts 11 are convex portions that project to the side of the circuit board 20 so as to touch heating elements. More specifically, the shapes and relative positions of the pair of receptive-shaped parts 11 are determined such that the pair of receptive-shaped parts 11 are more line-symmetric with respect to the center C between the two optical axes Lx of the pair of imaging devices 100, than the pair of the heat-dissipating members 40. The center C is a center line parallel to the two optical axes Lx, which is included in the plane that includes the two optical axes Lx of the lenses 101 of the pair of imaging devices 100.

[0033]

As described above, the heat that is dissipated from the heating elements such as the CPU 21 and the processing circuit 22 is conducted, through the heat-dissipating members 40, to one of the pair of receptive- shaped parts 11 that are more line-symmetric across the center C between the two optical axes Lx of the pair of imaging devices 100 than the pair of the heat-dissipating members 40, and then the dissipated heat is conducted from one of the pair of receptive-shaped parts 11 to the entirety of the housing 10.

[0034]

As described above, for example, the heating elements such as the CPU 21 and the processing circuit 22 differ from each other in its type, the installed position on the circuit board 20, and the size. For this reason, it is very difficult to arrange multiple heating elements at symmetrical positions across the center C between the optical axes Lx of the pair of imaging devices 100.

[0035]

However, in the present embodiment, even when the heating elements such as the CPU 21 and the processing circuit 22 are not arranged in line symmetry across the center C between the two optical axes Lx of the pair of imaging devices 100, the shapes and relative positions of the pair of receptive-shaped parts 11, which each one of the heating elements touches, are determined such that the pair of receptive-shaped parts 11 are more line-symmetric across the center C between the two optical axes Lx of the pair of imaging devices 100, than the two heating elements (e.g., the CPU 21 and the processing circuit 22). Due to such a configuration, when the housing 10 deforms due to changes in temperature, the horizontally-asymmetrical deformation of the housing 10 due to thermal expansion can be prevented, and the degradation of the stereo camera 1 due to thermal expansion can be prevented. When the pair of receptive shaped parts 11 that each one of the heating elements touches are shaped the same and line- symmetric with each other, the thermal expansion can be handled even better.

[0036]

As described above, according to the present embodiment, when the housing 10 deforms due to changes in temperature, the horizontally-asymmetrical deformation of the housing 10 due to thermal expansion can be prevented. Moreover, the degradation of the stereo camera 1 due to thermal expansion can be prevented.

[0037]

As described above, basically, it is desired that the pair of receptive-shaped parts 11 be bilaterally symmetrical in a complete manner. On the other hand, when the installation position or size of two heating elements (e.g., the CPU 21 and the processing circuit 22) significantly varies, instead of arranging the pair of receptive-shaped parts 11 in a perfect bilateral symmetry, it is desired that the relative positions and sizes of the pair of receptive shaped parts 11 be determined based on the differences in the relative positions and sizes of the two heating elements (e.g., the CPU 21 and the processing circuit 22). By so doing, the housing 10 may be prevented from being deformed in a horizontally-asymmetrical manner.

[0038]

In the above embodiment of the present disclosure, two receptive-shaped parts 11, two heating elements (e.g., the CPU 21 and the processing circuit 22), and two heat-dissipating members 40 are provided. However, no limitation is indicated thereby, and at least two receptive shaped parts, at least two heating elements, and at least two heat-dissipating members may be provided.

[0039]

Second Embodiment

[0040]

A second embodiment of the present disclosure is described below.

[0041]

In the second embodiment of the present disclosure, a vehicle control unit 300 provided with the stereo camera 1 according to the first embodiment of the present disclosure is described. Note that like reference signs are given to elements similar to those described in the first embodiment, and their detailed description is omitted in the description of the second embodiment of the present disclosure.

[0042]

FIG. 5 is a diagram illustrating a schematic configuration of the vehicle control unit 300 according to the second embodiment of the present disclosure. As illustrated in FIG. 5, the vehicle control unit 300 is provided for a vehicle 500, and controls the operation or movement of the vehicle 500. The vehicle control unit 300 calculates the distance to an object existing ahead of the vehicle 500 in the directions of travel using the stereo camera 1 as described above, and controls the operation or movement of the vehicle 500 based on the calculated distance.

[0043]

As illustrated in FIG. 5, the pair of lenses 101 that are provided for the stereo camera 1 are arranged so as to be able to capture the scene or an image ahead of the vehicle 500 in the directions of travel. The stereo camera 1 is arranged onto an upper side of the inner surface (on an interior side) of the front windshield of the vehicle 500, near the inner rearview mirror. The installation position at which the stereo camera 1 is arranged is not limited to the position as described above, and the stereo camera 1 may be any position as long as the conditions outside and ahead of the vehicle 500 in the directions of travel can be recognized at such a position.

[0044]

The stereo camera 1 calculates the distance to an object (to be measured) or obtains the distance data, based on the image data including the captured object. An object to be measured by the stereo camera 1 is, for example, another mobile object, a person, and an animal.

[0045]

The vehicle control unit 300 is provided with the stereo camera 1 that is installed in the room of the vehicle 500, a controller 310, a steering wheel 320, and a brake pedal 330. The stereo camera 1 has a function to capture an image of the sight ahead of the vehicle 500 in the direction of travel, and is arranged, for example, on the inner surface of the front windshield of the vehicle 500, near the rear-view mirror. [0046]

The relation between the stereo camera 1 and the vehicle control unit 300 is described below. The controller 310 of the vehicle control unit 300 performs various kinds of vehicle control based on the distance information between the stereo camera 1 and the object, which is calculated based on a disparity image received from the stereo camera 1.

[0047]

As an example of vehicle control, the controller 310 controls a steering system (controlled system) including a steering wheel 320, based on a disparity image received from the stereo camera 1, to avoid an obstacle. Such a vehicle control may also be referred to as a steering control. Moreover, for example, the controller 310 controls the brake pedal 330 (object to be controlled), based on a disparity image received from the stereo camera 1, to reduce speed and stop the vehicle 500. Such a vehicle control may also be referred to as a brake control. As described above, vehicle control such as a steering control or brake control is executed by the vehicle control unit 300 that includes the stereo camera 1 and the controller 310. Due to such a configuration, the driving safety of the vehicle 500 can be improved.

[0048]

It is assumed in the above description that the stereo camera 1 captures an image of the sight ahead of the vehicle 500. However, no limitation is intended thereby. In other words, the stereo camera 1 may be mounted so as to capture an image of a rear view or side view of the vehicle 500. In such a configuration, the stereo camera 1 can detect the position of a following vehicle in a rear direction of the vehicle 500 or the position of another vehicle travelling beside the vehicle 500 in parallel. Accordingly, the controller 310 can perform the above vehicle control upon detecting danger when, for example, the traffic lane in which the vehicle 500 is travelling is to be changed or two lanes of traffic are about to join into one.

[0049]

Moreover, for example, when it is determined that the risk of collision is increasing in a reversing operation to park the vehicle 500 based on the disparity image of an obstacle behind the vehicle 500, detected by the stereo camera 1, the controller 310 can perform the above vehicle control.

[0050]

As described above, according to the present embodiment, even when the heating elements such as the CPU 21 and the processing circuit 22 are not arranged in line symmetry across the center C between the two optical axes Lx of the pair of imaging devices 100, the shapes and relative positions of the pair of receptive- shaped parts 11 that each one of the heating elements touches are determined such that the pair of receptive-shaped parts 11 are more line-symmetric than the heating elements. Due to this configuration, when the housing 10 deforms due to changes in temperature, the horizontally-asymmetrical deformation of the housing 10 due to thermal expansion can be prevented. Accordingly, the degradation in performance of the stereo camera 1 due to thermal expansion can be prevented, and the error effect on the calculation processes of the distance between the stereo camera 1 and the object can be reduced.

[0051]

The stereo camera 1 is satisfactory as long as it is mounted in an article whose distance to an object to be measured varies. Accordingly, the stereo camera 1 may be provided for a mobile object such as a ship and a train in addition to the vehicle 500. When the stereo camera 1 is used for factory automation (FA), the stereo camera 1 may also be applied to a fixture such as a building.

[0052]

This patent application is based on and claims priority to Japanese Patent Application Nos. 2019-140072 and 2020-101630, filed on July 30, 2019, and June 11, 2020, respectively, in the Japan Patent Office, the entire disclosures of which are hereby incorporated by reference herein. [Reference Sings List]

[0053] I Capturing unit

10 Housing

I I Receptive-shaped part 20 Circuit board

40 Heat-dissipating member

100 Imaging device 300 Vehicle control unit 310 Controller

Claims

[CLAIMS]

[Claim 1]

A capturing unit comprising:

a pair of imaging devices;

a circuit board provided with at least two parts related to an operation of the pair of imaging devices;

a housing holding the circuit board;

a pair of convex portions disposed on the housing across a center between two optical axes of the pair of imaging devices in the housing, the pair of convex portions projecting toward the circuit board; and

at least two heat-dissipating members each of which is disposed on one of the pair of convex portions to touch one of the at least two parts and dissipate heat from the one of the at least two parts,

wherein the pair of convex portions are disposed and shaped to be more line-symmetric across the center between the two optical axes of the pair of imaging devices than the at least two parts.

[Claim 2]

A capturing unit comprising:

a pair of imaging devices;

a housing holding the circuit board;

a pair of convex portions disposed in line symmetry across a center between two optical axes of the pair of imaging devices in the housing, the pair of convex portions projecting toward the circuit board; and

at least two heat-dissipating members each of which is disposed on one of the pair of convex portions to touch one of the at least two parts and dissipate heat from the one of the at least two parts.

[Claim 3]

The capturing unit according to claim 1 or 2,

wherein the at least two heat-dissipating members are made of a thermal interface material.

[Claim 4]

The capturing unit according to any one of claims 1 to 3,

wherein the at least two parts include an image processing circuit configured to process images captured by the pair of imaging devices.

[Claim 5]

The capturing unit according to any one of claims 1 to 4,

wherein the at least two parts include a processing circuit configured to perform disparity computation based on images captured by the pair of imaging devices.

[Claim 6]

A capturing unit comprising:

at least two convex portions;

at least two heat-dissipating members disposed to contact at least some of the at least two convex portions; and

at least two parts disposed to contact at least some of the at least two heat-dissipating members. [Claim 7]

A vehicle control unit comprising:

the capturing unit according to any one of claims 1 to 6; and

a controller configured to perform various kinds of vehicle control based on a distance to an object calculated based on a disparity image obtained by the capturing unit.