JP4476468B2 - Legged mobile robot - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a legged mobile robot including a manipulator, and more particularly to a humanoid legged mobile robot including a head, arms, torso, waist, legs, and the like.
[0002]
[Prior art]
The autonomous mobile robot is provided with a device for detecting a floor surface, a wall surface, an obstacle, or the like when moving. For example, Japanese Patent Laid-Open No. 6-43935 discloses a means for irradiating a predetermined pattern of slit light that intersects the traveling direction, a means for imaging a portion irradiated with the slit light, and a pattern of the captured slit light. And the traveling robot provided with the means to determine the presence or absence of the obstruction ahead of the traveling direction is disclosed. Japanese Patent Application Laid-Open No. 6-83442 uses a light cutting method to calculate three-dimensional coordinate data based on a light cutting line formed on an obstacle surface by irradiation with slit light, and this three-dimensional coordinate data. A technique for controlling the running of a robot based on the above is disclosed.
[0003]
In the conventional biped robot, the walking pattern is determined on the assumption that the height and inclination of the floor are known. In addition, some height estimation errors are absorbed by compliance control so that the robot can walk without falling. In addition, if the floor cannot be measured in advance, the walking path cannot be corrected accurately, or an unknown obstacle appears, compliance control alone is not sufficient and can cause a fall. Biped robots with external sensors have also been studied. In a humanoid robot having legs and arms, the external sensor as described above is provided on the head.
[0004]
[Problems to be solved by the invention]
However, when an external sensor of a robot equipped with a manipulator, particularly a humanoid robot, is provided on the head, there are the following problems.
[0005]
The first problem is the interference of the manipulator with an external sensor. For example, when trying to measure the floor surface in the moving direction, the front floor surface is irradiated from the light source provided at the head, but if the irradiation light is blocked by the manipulator, the floor surface is sufficient. Cannot illuminate the area. In addition, for example, when a humanoid robot moves while holding a large load on its arm, the irradiation light is blocked over a wide range.
[0006]
The second problem is the direction of the external sensor. In a humanoid robot, there is a case where the head is tilted in the front-rear direction or the left-right direction or the direction of the head is changed by the movement of the neck joint. In addition, the upper body of the robot may be tilted or changed in the front-rear direction or the left-right direction depending on the movement of the body part. Since the direction of the external sensor provided on the head changes due to these movements, the state of the front floor surface cannot always be detected properly.
[0007]
The present invention has been made in consideration of the above circumstances, and even in a robot having a manipulator, the manipulator does not interfere with the measurement, and always detects surrounding objects, particularly objects below, in an appropriate state. An object of the present invention is to provide a legged mobile robot capable of measuring distance and the like.
[0008]
In particular, in a humanoid legged mobile robot consisting of the head, torso, arms, legs, etc., the arm does not interfere with the measurement, and it is always in good condition even when each joint part is moved. It is an object of the present invention to provide a legged mobile robot capable of measuring a distance by detecting a floor surface, a wall surface, an obstacle or the like in a traveling direction.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a leg portion coupled to the main body for the purpose of movement, and a manipulator coupled to the main body for moving an object in space, In a legged mobile robot in which a coupling portion between the manipulator and the main body is disposed above a coupling portion between the leg portion and the main body, the coupling portion between the manipulator and the main body is below and The gist of the legged mobile robot is characterized in that an external sensor for detecting an object to be measured is provided above the joint between the leg and the main body.
[0010]
The legged mobile robot of the present invention is a humanoid robot having a waist part, and the external sensor is arranged at or around the waist part.
[0011]
In the legged mobile robot of the present invention, the external sensor includes a light emitting unit that irradiates slit light and an image capturing unit that captures an optical cutting line formed by the slit light on the measurement target object. It is characterized by that.
[0012]
Further, the legged mobile robot of the present invention is characterized by comprising distance calculation means for calculating a distance to the measurement target object based on an image picked up by the image pickup means.
[0013]
The legged mobile robot of the present invention is characterized by comprising leg control means for controlling the movement of the leg based on the distance information calculated by the distance calculation means.
[0014]
In addition, the legged mobile robot of the present invention is characterized in that the surroundings are monitored using a light cutting method based on the image picked up by the image pickup means.
[0015]
In the legged mobile robot of the present invention, the imaging means is composed of at least two cameras, and the same object in each image captured by these cameras is associated with the associated object. The distance to the object is calculated using the parallax.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main configuration of a legged mobile robot according to the embodiment. This configuration measures the distance on the floor, walls, and obstacles on the robot's moving path and its surroundings, and measures the distance so that the landing position of the foot during biped walking is appropriate. The purpose of this is to control.
[0017]
In FIG. 1, reference numeral 1 denotes a laser light source (light emitting means) that irradiates a measurement target object (such as a floor surface) with multi-slit light. Reference numerals 2a and 2b denote a narrow base length camera (imaging means) and a wide base length camera (imaging means) that capture an image of the measurement target object irradiated with slit light from the laser light source 1, respectively. The narrow base length camera 2 a is provided relatively near the laser light source 1, and the wide base length camera 2 b is provided relatively far from the laser light source 1. That is, in this embodiment, at least two cameras are provided, and the camera and the laser light source are arranged so that the distance between the first camera and the laser light source is different from the distance between the second camera and the laser light source. Yes. Reference numeral 3 denotes a light emission control unit (light emission) for controlling the light emission timing of the laser light source 1 and the imaging timing of the narrow baseline length camera 2a and the wide baseline length camera 2b by outputting a timing signal to the laser light source 1. Control means).
[0018]
An image capturing unit 4 captures an image captured by the camera 2 and stores it in an image memory after A / D conversion (analog / digital conversion). 5 is based on the image captured by the image capturing unit 4. It is a distance estimation part (distance calculation means) which calculates the distance to a measurement object. Reference numeral 8 denotes a movement route determination unit that determines the movement route of the robot. Reference numeral 6 denotes a landing position of the robot foot based on the route information determined by the movement route determination unit 8 and the distance calculation result by the distance estimation unit 5. The landing position determination unit 7 is a leg control unit (leg control means) that controls a motor that drives the robot leg while balancing the robot so that the foot is brought to the landing position determined by the landing position determination unit 6. is there.
[0019]
FIG. 2 is a cross-sectional view showing the principle of the light cutting method used in this embodiment. In FIG. 2, reference numeral 901 denotes a slit light source provided in the three-dimensional measuring device, 902 denotes an imaging lens provided in the three-dimensional measuring device, 903 denotes an image formation surface by the lens 902, and 905 denotes a connection. This is the center point of the image plane 903, and this center point 905 is the intersection of the image plane 903 and the imaging direction axis. Reference numeral 901a denotes a slit light surface irradiated from the slit light source 901, reference numeral 910 denotes a measurement target object, and reference numeral 911 denotes one of irradiation points where the slit light surface 901a irradiates the measurement target object.
[0020]
Here, the distance between the slit light source 901 and the center of the lens 902 is L (base line length). A reference line on the drawing indicates a direction perpendicular to a measurement surface (a surface perpendicular to the cross section of FIG. 6) including a line connecting the slit light source 901 and the lens 902. The angle of the slit light with respect to the measurement surface is θ, and the angle of the line connecting the center of the lens 902 and the irradiation point 911 with respect to the measurement surface is φ. Here, in order to obtain the distance Z from the measurement surface to the measurement target object 910, the following equation may be calculated.
[0021]
Z = L · tan (θ) · tan (φ) / (tan (θ) + tan (φ))
However, “tan ()” represents a tangent function.
[0022]
The above φ is expressed by the following equation using an angle φ0 with respect to the imaging surface in the imaging direction (a direction connecting the center point 905 and the center of the lens 902) and a displacement angle φ1 of the irradiation point 911 with respect to the imaging direction.
[0023]
φ = φ0 + φ1
[0024]
Further, the displacement angle φ1 is expressed by the following equation using the distance l between the lens 902 and the imaging plane 903 and the displacement Δx from the center point 905 of the image of the irradiation point 911 on the imaging plane 903.
[0025]
φ1 = arctan (Δx / l)
However, “arctan ()” represents a tangent inverse function.
[0026]
As described above, the slit light is irradiated not only on the cross section but also on the surface of the measurement target object 910 so as to form a linear cutting line. The distance to the location can be measured. In this embodiment, since the laser light source 1 irradiates multi-slit light, it is possible to measure the irradiated range using the optical cutting line formed by each.
[0027]
FIG. 3 is a side view showing an external structure of the legged mobile robot according to the present embodiment. In this figure, reference numeral 20 denotes a floor surface, 20a denotes a projecting surface existing on the floor surface 20, and 21 denotes a humanoid robot. The humanoid robot 21 includes various parts such as an upper arm part 22a, a lower arm part 22b, a hand part 22c, a trunk part 23 (main body), a waist part 24 (main body), and a leg part 25. The upper arm portion 22a, the lower arm portion 22b, the hand portion 22c, and the joint connecting them constitute a multi-joint manipulator for moving the object in the space.
[0028]
Reference numerals 31 to 34 denote rotation axes of joints that connect each part of the humanoid robot 21. For example, the upper arm portion 22 a is attached to the trunk portion 23 via a joint, and performs a movement as shown by a broken arrow line (A) illustrated around the rotation shaft 31. For example, when the humanoid robot 21 carries a load, the elbow joint can be bent so that the upper arm portion 22a and the lower arm portion 22b form an angle of approximately 90 degrees and the load can be held there.
[0029]
Reference numeral 27 denotes an external sensor. The external sensor 27 incorporates at least the laser light source 1, the narrow base length camera 2a, and the wide base length camera 2b shown in FIG. At the same time, the irradiated floor surface 20 and projection surface 20a are imaged by either or both of the narrow base length camera 2a and the wide base length camera 2b. And the distance to each optical cutting line formation position is measured according to the above-mentioned principle, the landing position of the foot is determined, and the movement of the leg is controlled.
[0030]
In a normal size humanoid robot, the difference described below may occur between the case where an external sensor is provided on the waist as shown in FIG. 3 and the case where an external sensor is provided on the head as in the prior art. It has been proved by experiments.
[0031]
(1) Maximum baseline length The baseline length, that is, the distance between the slit light source and the camera, can be made wider when it is provided at the waist than when it is provided at the head. For example, the maximum baseline length when it is provided on the head is about 7 centimeters (cm), whereas when it is provided on the waist, it can be about 20 cm.
[0032]
(2) Distance to the floor surface The distance from the external sensor to the floor surface is smaller when it is provided on the waist than when it is provided on the head. For example, when it is provided on the head, it is about 150 cm, whereas when it is provided on the waist, it is about 80 cm.
[0033]
(3) Measurement accuracy Due to the difference in the maximum base line length and the distance to the floor surface, it is possible to perform measurement with higher accuracy when it is provided at the waist than when it is provided at the head. For example, when photographing using the same type of camera and lens, the measurement accuracy of the external sensor provided on the head is approximately ± 55 millimeters (mm), whereas the measurement is performed on the waist. The system is about ± 5 mm, and an accuracy difference of 10 times or more occurs in absolute value.
[0034]
(4) Necessity of anti-seismic / follow-up function In order to realize a distance measurement system of about ± 5 mm with an external sensor provided on the head, it is necessary to use a telephoto lens for imaging a light section line, but biped walking is performed. In order to perform stable measurement by providing a telephoto lens with a narrow angle of view in this way on the head of the robot, an anti-seismic function to make it less susceptible to the vibration caused by movement and the imaging target are followed. It is necessary to provide a tracking function. When an external sensor is provided on the waist, an accuracy of ± 5 mm can be realized without particularly adding these functions.
Therefore, it is advantageous to provide an external sensor on the waist from the viewpoint of the complexity and cost of the configuration of the robot.
[0035]
(5) When an external sensor is provided in the visual field head, a wide range of up, down, left, and right can be captured in the visual field by moving the neck joint or the like. On the other hand, when an external sensor is provided on the waist, the field of view is basically only forward, and the field of view is limited even when the waist can be rotated to the left or right to some extent.
[0036]
(6) Environment recognition / remote control coexistence When an external sensor is provided on the head, it is necessary to perform time recognition processing for recognition of the robot's operating environment and distance measurement to the floor, etc. Control becomes complicated. On the other hand, since the external sensor provided in the waist only measures the floor surface and the like, it can coexist with environment recognition / remote control relatively easily.
[0037]
(7) Laser light reflection intensity When an external sensor is provided on the head, the intensity of the laser light reflected on the floor or the like and incident on the camera is 0.29 times, whereas an external sensor is provided on the waist. That in the case is 3.5 times. There is an opening of about 12 times between these two, and when an external sensor is provided on the waist, the optical cutting line can be recognized more reliably and stable measurement can be performed.
[0038]
(8) When an external sensor is provided on the concealed head of the floor surface by the arm portion, a part of the floor surface is blocked in a state where the arm portion is protruded forward from the trunk portion, and the measurable range is narrowed. In addition, when the baggage is held by the arm or held in the hand in front of the torso, the measurement range may be further narrowed and measurement may not be possible at all. On the other hand, when an external sensor is provided on the waist, there is no or no overwhelming floor covering by the arm or hand, and the floor or the like can be measured stably even during robot operation. .
[0039]
(9) Positioning accuracy of the waist position relative to the floor When an external sensor is provided on the head, there is a degree of freedom of movement from the waist to the head, so geometric correction between these is required and positioning accuracy is Lower. On the other hand, when an external sensor is provided on the waist, the waist and the external sensor are directly connected and are integrated even during the operation of the robot, so positioning accuracy is high.
[0040]
As described above, compared to the case where an external sensor is provided on the head as in the prior art, the case where it is provided on the waist as in the present embodiment is due to the maintenance of measurement accuracy, cost, measurement direction, and manipulator. This is advantageous in terms of concealment effects.
[0041]
Next, the proper use of the two cameras in this embodiment will be described. As shown in FIG. 1, the robot according to the present embodiment includes a narrow base length camera 2a and a wide base length camera 2b. When the angle of view of the narrow baseline length camera 2a and the wide baseline length camera 2b are equal to each other, the image taken by the narrow baseline length camera 2a exists in a wider distance range than the image taken by the wide baseline length camera 2b. The object to be measured can be captured. On the other hand, as is apparent from the principle of the light cutting method, by using an image taken with the wide baseline length camera 2b, distance measurement can be performed with higher accuracy than when using an image taken with the narrow baseline length camera 2a. it can. That is, by appropriately using the narrow base length camera 2a and the wide base length camera 2b as appropriate, it is possible to measure the distance to the measurement target object in a wider range with higher accuracy. That is, for example, first, the distance to the object to be measured is measured with rough accuracy using the narrow baseline length camera 2a, and if necessary, the imaging direction of the wide baseline length camera 2b is adjusted according to the distance measurement result. Next, the distance to the object to be measured is measured with high accuracy using the wide baseline length camera 2b. Thereby, it becomes possible to measure a measurement target object in a wide distance range with high accuracy.
[0042]
Further, by performing binocular stereoscopic viewing using these two cameras, it is possible to detect the floor surface with high accuracy and to detect distant obstacles with high accuracy. In order to perform such binocular stereoscopic vision, for example, images captured by both cameras are each A / D converted (analog / digital converted) into an image memory, and the corresponding processing means converts these images into a plurality of images. The same imaging object included in each is associated, and the distance to the corresponding imaging object is calculated using the parallax of the object based on the principle of triangulation. Details of such measurement using binocular stereoscopic vision are described in, for example, “Vehicle Environment Recognition Device” (Japanese Patent Laid-Open No. 9-159442) filed by the present applicant.
[0043]
In the above embodiment, two cameras, the narrow base length camera 2a and the wide base length camera 2b, are used. However, the number of cameras is arbitrary and may be one or three or more. It may be.
[0044]
In the above-described embodiment, the external sensor is provided at the waist, but the external sensor is not limited to the waist, but may be provided at an arbitrary position between the leg and the manipulator in the vertical direction, for example, around the waist. Also good. Further, not only a humanoid robot, but in a legged mobile robot having a manipulator arranged above the leg, when an external sensor is provided at an arbitrary position between the leg and the manipulator in the vertical direction The same effect can be obtained.
[0045]
Here, the reason why the external sensor is provided below the manipulator is to avoid interference by the manipulator during floor surface measurement as described above. The reason why the external sensor is provided above the leg is to enable a wide measurement of a necessary range. For example, when an external sensor is provided on the leg, for example, problems described below occur.
[0046]
FIG. 4 is a side view showing a multi-slit light irradiation range when an external sensor is provided on a leg of a humanoid robot. In FIG. 4, reference numeral 21 is a humanoid robot, 40 is a floor surface, 40 a is an upper surface of an obstacle existing on the floor surface 40, 40 b is a side surface of the obstacle, and 47 is a leg of the humanoid robot 21. The provided external sensor 48 is a multi-slit light irradiation range by the external sensor 47. As shown in the figure, in this example, since the installation position of the external sensor 47 is too low, a part of the side surface 40b of the obstacle can be measured, but the upper surface 40a and the floor surface on the other side of the obstacle are measured. Can not do it. By limiting the measurement range in this way, the merit of the legged robot that can pass over obstacles of a certain height cannot be utilized.
[0047]
In addition, even in the situation where there is no obstacle as shown in FIG. 4, if the installation position of the external sensor is too low, a sufficient angle for irradiating the floor surface cannot be obtained, and the measurement system of the far side becomes worse, When going down the stairs, there is a disadvantage that the irradiation angle necessary for measuring the stairs surface cannot be obtained.
[0048]
【The invention's effect】
As described above, according to the present invention, in the legged mobile robot, the external sensor for detecting the lower measurement target object is located above the coupling portion between the leg portion and the main body and coupled between the manipulator and the main body. Therefore, the object to be measured can be detected and measured without receiving interference from the manipulator.
[0049]
In addition, according to the present invention, since the external sensor is arranged around the waist or around the waist of the humanoid robot, the floor surface and obstacles in the forward direction, that is, the traveling direction are always easy regardless of the movement of the neck joint and the torso. And it becomes possible to detect and measure stably.
[0050]
According to the invention, the external sensor includes the light emitting means for irradiating the slit light and the imaging means for imaging the light cutting line formed on the measurement target object by the slit light. Since the distance to the measurement target object is calculated based on the captured image using a light cutting method or the like, the legged mobile robot knows the distance to the floor surface and can detect the shape of the floor surface and the like. Further, based on the calculated distance and shape, the landing position of the foot can be determined and the movement of the leg can be controlled.
[0051]
According to the present invention, the imaging means is composed of at least two cameras, associates the same object in each image captured by these cameras, and uses the parallax of the associated object. In order to calculate the distance to the object, it is possible to measure the lower floor with high accuracy and detect distant obstacles with high accuracy using binocular stereoscopic vision.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of a legged mobile robot according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the principle of a light cutting method used in the embodiment.
FIG. 3 is a side view showing an external structure of a legged mobile robot according to the embodiment.
FIG. 4 is a side view showing an example when the installation position of the external sensor in the robot is inappropriate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser light source 2a Narrow base length camera 2b Wide base length camera 3 Light emission control part 4 Image capture part 5 Distance estimation part 6 Landing position determination part 7 Leg control part 8 Movement path determination part 20 Floor 20a Projection surface 21 Humanoid robot 22a Upper arm portion 22b Lower arm portion 23 Trunk portion 24 Lumbar portion 25 Leg portion 27 External sensor 28 Multi-slit light irradiation range 31, 32, 33, 34 Joint rotation axis A Broken line indicating movement of upper arm portion 22a

Claims (7)

A leg coupled to the body for movement; and a manipulator coupled to the body for moving an object in space, wherein the coupling between the manipulator and the body is the leg. In the legged mobile robot disposed above the joint between the main body and the body,
A leg-type movement characterized by comprising an external sensor that detects an object to be measured below the joint between the manipulator and the main body and above the joint between the leg and the main body. robot. The legged mobile robot is a humanoid robot having a waist.
The legged mobile robot according to claim 1, wherein the external sensor is arranged at or around the waist. The said external sensor is equipped with the light emission means which irradiates slit light, and the imaging means which images the optical cutting line which this slit light forms on the said measurement object, The Claim 1 or 2 characterized by the above-mentioned. Legged mobile robot. The legged mobile robot according to claim 3, further comprising a distance calculating unit that calculates a distance to the measurement target object based on an image captured by the imaging unit. The legged mobile robot according to claim 4, further comprising leg control means for controlling movement of the leg portion based on distance information calculated by the distance calculation means. The legged mobile robot according to any one of claims 3 to 5, wherein surroundings are monitored using an optical cutting method based on an image picked up by the image pickup means. The imaging means is composed of at least two cameras, associates the same object in each image captured by these cameras, and calculates the distance to the object using the parallax of the associated object The legged mobile robot according to any one of claims 3 to 6, characterized in that:

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