Patent Application
20090062974
The present invention relates to a movement system of a mobile object such as a mobile robot, a running vehicle, or the like wherein the mobile object is accompanied by a mobile object other than the main body and autonomously moves while obtaining information on ambient environment.
Examples of the movement system comprising a mobile object as the main body and an accompanying mobile object are the method for connecting and disconnecting an automatic guided vehicle and a loading truck and the system thereof shown in Japanese Patent Application Laid-Open Publication Nos. H10-24836 and H6-107168. A structure of a connectable and disconnectable joint between an automatic guided vehicle and a loading truck is shown in the patent documents. Further, in the conveying system with a conveying convoy shown in Japanese Patent Application Laid-Open Publication No. H6-107168, the combination of an automatic guided vehicle and a towed convoy and a configuration of a towed truck having a steering mechanism are shown.
In the configuration of an aforementioned automatic guided vehicle and a truck towed thereby, the truck is towed by mechanically connecting them to each other. Such a configuration is effective when they move in an unchanged state from the start point to the end point of transportation. When the number of the towed trucks or the convoy changes or they separate or merge in the middle of the start point and the end point of the transportation however, a problem here is that they have to be disconnected and connected mechanically and hence they are hardly automated. Further, another problem is that, since the connection is regulated by mechanical structural conditions, a towed truck is limited to the primarily intended and planned mechanism and shape and it is difficult to adjust the towed truck when the specifications of a conveyed object are changed.
An object of the present invention is, in view of the above conventional problems, to provide a system and a control method of an autonomous mobile robot that moves autonomously and jointly or moves separately while a guided vehicle and a truck or the like are not mechanically connected and information on ambient environment is obtained.
The present invention is an autonomous mobile robot system having plural mobile robots and integrative planning means to plan the moving zone of the plural mobile robots, wherein: the integrative planning means is installed on the plural mobile robots including a main mobile robot to travel autonomously and a subordinate mobile robot to travel on the basis of the instructions of the main mobile robot; and each of the plural mobile robots is provided with, at least, measurement means to measure the situation of ambient environment, communication means to communicate between the integrative planning means and the other mobile robot, main device position recognition means to recognize the position of the mobile robot, subordinate device position recognition means to recognize the position of the other mobile robot, travel planning means to plan travel routes of the mobile robot and the other mobile robot, and travel control means to control a drive mechanism in accordance with the travel planning means.
Here, the subordinate mobile robot may be designated to be changed to a main mobile robot by the instructions of the integrative planning means and may travel autonomously when the subordinate mobile robot is separated from the interlocked main mobile robot and travels.
Further, when the travel route along which the main mobile robot travels merges with another travel route, the main mobile robot may be designated to be changed to a subordinate mobile robot by the instructions of the integrative planning means and may cooperatively travel after merger by the instructions of another main mobile robot located on the other travel route.
Furthermore, the present invention is a method for controlling plural autonomous mobile robots by integrative planning means to plan the moving zone of the plural mobile robots, wherein: the integrative planning means designates the plural mobile robots as a main mobile robot to travel autonomously and a subordinate mobile robot to travel on the basis of the instructions of the main mobile robot; each of the plural mobile robots recognizes the positions of the mobile robot and the other mobile robot by measuring the situation of ambient environment and plans the travel routes of the mobile robot and the other mobile robot; and the main and subordinate mobile robots cooperatively travel along the travel routes on the basis of the instructions of the main mobile robot designated by the integrative planning means.
Here, the subordinate mobile robot may be designated to be changed to a main mobile robot by the instructions of the integrative planning means and may travel autonomously when the subordinate mobile robot is separated from the interlocked main mobile robot and travels.
By the present invention, a main mobile robot controls a subordinate mobile robot and thereby it is possible to reduce mutual interference during traveling and travel effectively. Further, a main mobile robot and a subordinate mobile robot may be separated and merged automatically and easily. As a result, a subordinate mobile robot once separated can merge with a main mobile robot and travel together and hence it is possible to reduce the frequency of the travel of the robots and enhance safety in travel environment where the robots intersect with a human body such as a worker.
Embodiments according to the present invention are hereunder explained. The concept of an autonomous mobile robot system according to an embodiment of the present invention is shown in
The reference character 5 represents integrative planning means that plans and indicates the moving zone of at least one autonomous mobile robot group C. In the present embodiment, the integrative planning means 5 plans travel routes of an autonomous mobile robot group C at a travel node level on the basis of a task database 7. Then the autonomous mobile robot 1 plans travel routes at a track level on the basis of the instructions on the travel routes planned at the travel node level.
On this occasion, the autonomous mobile robot 1 obtains circumstances E varying from hour to hour of the travel routes around production lines in accordance with the traveling and plans the travel routes of the autonomous mobile robot 1 and the subordinate mobile robots 2 at the track level in real time. The travel routes of the subordinate mobile robots 2 at the track level are transmitted from the autonomous mobile robot 1 to the subordinate mobile robots 2 and the traveling of the subordinate mobile robots 2 is controlled.
More specific configurations are explained hereunder.
The integrative planning means 5 plans the destinations of the plural autonomous mobile robots 1 and travel nodes (at the travel node level) leading to the destinations and instructs the autonomous mobile robots 1 via the communication means 6. Further, when plural autonomous mobile robots 1 are operated in combination, the autonomous mobile robot 1a is designated as a main device and the autonomous mobile robot 1b is designated as a subordinate device, respectively.
An autonomous mobile robot 1 comprises at least the following components. The reference character 11 represents measurement means to measure the position of a physical body and the relative positions of plural autonomous mobile robots 1 as the ambient environment of travel routes and the measurement means 11 is placed at an upper portion of the autonomous mobile robot 1 so as to ensure unobstructed views. The examples of the measurement means 11 are a laser range finder to scan a horizontal plane with laser beams and measure a distance on the basis of the time required for the reflection from a physical body, a CCD stereovision sensor system to measure the distance of an object on the basis of the parallax of plural CCD camera images, and a landmark-used sensor system to take in landmark information such as a two-dimensional bar code or the like attached to a physical body with a CCD sensor and to measure a distance on the basis of the landmark information and the view angle thereof.
The reference character 12 represents communication means to transmit and receive information between the integrative planning means 5 and another autonomous mobile robot 1. The examples are communication means using radio waves such as a wireless LAN or the like and light communication means using infrared light pulses or the like. The reference character 13 surrounded by the broken line represents computation means to compute with a CPU or the like and the computation means 13 contains main device position recognition means 14, subordinate device position recognition means 15, travel planning means 16, and travel control means 17.
The main device position recognition means 14 recognizes the position of the autonomous mobile robot 1 acting as the main device on the basis of the information obtained by the measurement means 11. An example of the method for obtaining information in the measurement means 11 is the technology of generating a map from the distance information of a laser range finder shown in “a device and a method for generating a map image by laser measurement” of Japanese Patent Application Laid-Open Publication No. 2005-326944 and recognizing the position of itself on the map.
In summary, that is a technology of: measuring the orientation and the distance to an obstacle several times by moving a laser distance sensor; extracting a feature point by histogram from an image being obtained by the measurements and showing the position of the obstacle; and generating a map by superimposing the images having feature points most coinciding with each other. Here, the main device position recognition means 14a recognizes the position of the autonomous mobile robot 1a itself designated as the main device.
The subordinate device position recognition means 15 (15a) is used for the autonomous mobile robot 1a designated as the main device to recognize the position of the autonomous mobile robot 1b designated as a subordinate device. Here, the relative position of the autonomous mobile robot 1b (the distance and the orientation from the autonomous mobile robot 1a) is measured on the basis of the information on the ambient environment obtained by the measurement means 11a. An example of the measurement is explained in reference to
The position of the center Ga of the autonomous mobile robot 1a is assumed to be represented by (x, y, θ) on the basis of the recognition result of the main device position recognition means 14a. The measurement means 11a captures one side of the subordinate autonomous mobile robot 1b and the subordinate device position recognition means 15a recognizes the autonomous mobile robot 1b from the shape pattern of the side and measures the distance (α and β) from the center Ga and the inclination γ. The relative position of the center Gb of the autonomous mobile robot 1b is expressed by (α, 62 , γ). Further, as another method, there is a method of obtaining the position of the autonomous mobile robot 1a, which is measured and recognized from the side of the autonomous mobile robot 1b by the main device position recognition means 14b of the autonomous mobile robot 1b, by the main device position recognition means 14a via the communication means 12b and the communication means 12a.
The travel planning means 16a of the autonomous mobile robot 1a designated as the main device plans the travel routes of both the autonomous mobile robots 1a and 1b on the basis of the distances of surrounding physical bodies obtained by the measurement means 11a and the positions of the autonomous mobile robots 1a and 1b.
Firstly, the integrative planning means 5 plans the movement through the travel nodes P1, P2, and P3 at the travel node level. As the initial movement plan (travel plan) of the autonomous mobile robot 1a, the travel planning means 16a makes a plan at a track level to apply rectilinear travel T1 (0, b12, v) from P1 to P2 and curvilinear travel T2 (r23, c23, v) from P2 to P3. The reference characters “a” and “b” represent distances, “r” a radius of rotation, “c” an angle of rotation, and “v” a traveling speed. The center of the travel route is the line L and the allowance is a prescribed error “e”.
Here, when the position (x+α, y+β, θ+γ) of the autonomous mobile robot 1b deviates from the error range La-Lb, replanning is carried out. More specifically, in
The travel plan made by the travel planning means 16a of the autonomous mobile robot 1a designated as the main device is sent to the travel planning means 16b of the autonomous mobile robot 1b via the communication means 12. Travel control means 17b: controls a drive mechanism 18b so as to follow the travel plan; and moves the autonomous mobile robots 1 on the travel plane G.
In such a configuration as to combine plural autonomous mobile robots 1, a main device controls a subordinate device and thereby it is possible to: reduce interference such as collision between the autonomous mobile robots 1 at a corner when they travel in a convoy; and travel effectively. Further, in a travel environment where the autonomous mobile robots 1 intersect with a person such as a worker, by traveling in a convoy, it is possible to reduce the frequency of the movement of the robots and enhance the safety.
In a robot system to integrate plural autonomous mobile robots 1 and control the movement thereof, it is possible to: add a loader mechanism to load parts needed in production lines to the autonomous mobile robots 1; and convey the parts to arbitrary places by branching for example. The aspects are shown in
In
Here, the autonomous mobile robot 1b: follows the instructions (control) of the autonomous mobile robot 1a until it reaches the branch; after the branch, is designated to be changed from the subordinate device to a main device by the instructions of the integrative planning means 5; generates the travel route L2 by itself; autonomously travels; and reaches the destination D (1b′).
The operations after unloading at the destination D are shown in
Here, when the autonomous mobile robot 1a that has been separated at the branching exists on the travel route L1 in the vicinity of the merging point at the time of the merging, the autonomous mobile robot 1b is designated to be changed to a subordinate device having the autonomous mobile robot 1a as the main device and travels together under the instructions of the integrative planning means 5 (1a′, 1b′). When an autonomous mobile robot 1 other than the autonomous mobile robot 1a exists in the vicinity of the merging point, the autonomous mobile robot 1 is designated as a main device and the autonomous mobile robot 1b is designated to be changed to a subordinate device by the instructions of the integrative planning means 5. Thereafter, the convoy travels along the travel route L1 in accordance with the instructions of the autonomous mobile robot designated as the main device.
In this way, by changing the autonomous mobile robot designated as a subordinate device from the subordinate device to a main device at the time of branching and from the main device to the subordinate device at the time of merging, it is possible to smoothly control the operations when the autonomous mobile robot branches and merges.
Although both the robots are autonomous mobile robots in the above first embodiment, since the autonomous mobile robot 1a acting as the main device makes the travel plan of the autonomous mobile robot 1b acting as the subordinate device when they are operated in combination, the measurement means 11b, the main device position recognition means 14b, the subordinate device position recognition means 15b, and the travel planning means 16b of the autonomous mobile robot 1b acting as the subordinate device are not necessarily required.
The second embodiment is shown in
Further, since the subordinate mobile robot 2 has no measurement means as stated above, it is inferior in responsiveness to the change of ambient environment. For example, the measurement means 11 of the autonomous mobile robot 1 acting as the main device may undesirably have a blind spot when the subordinate mobile robot 2 approaches a suddenly pop-up human body.
To cope with the problem, as the third embodiment shown in
Further, the subordinate mobile robot 2 is provided with identification means 24 measured by the second measurement means 19 in
Further,
The subordinate device position recognition means 15 recognizes the device number of the subordinate mobile robot 2 and the relative position of the subordinate mobile robot 2 to the autonomous mobile robot 1 on the basis of the device number and the identification means 24 of the main device 1 measured by the second measurement means 19. In this way, it is possible to install the identification means 24 and the second measurement means 19 inversely with the third embodiment.
Further, it is possible to control plural subordinate mobile robots 2a and 2b by introducing the device numbers of mobile robots like the fifth embodiment shown in
The data obtained by the measurement are accumulated in the subordinate device position recognition means 15 of the autonomous mobile robot 1 and the positions of the plural subordinate mobile robots 2 are recognized. Then on the basis of the recognition, the travel plans of the plural subordinate mobile robots 2 are made by the travel planning means 16 and the planned travel routes are transmitted to the subordinate mobile robots 2a and 2b respectively via the communication means 12, 21a, and 21b.
By controlling drive mechanisms 23a and 23b with the travel control means 22a and 22b respectively, it is possible to cooperatively move the autonomous mobile robot 1 acting as the main device and the plural subordinate mobile robots 2 as a whole.
In
The configuration of the cooperative operations of a main mobile robot and plural subordinate mobile robots is clarified in the aforementioned fifth embodiment. A possible pattern of cooperative operations of plural robots in the actual operations is that: a main mobile robot in tandem takes plural subordinate robots with the main mobile robot to a workplace as shown in
Such operational control can be carried out by: configuring the subordinate mobile robots 1b, 1c, and 1d similarly to the main mobile robot 1a described in the first embodiment; and applying the operations shown in
Such operations are effective in improving work efficiency by parallelizing the operations. A problem thereof however is the equipment cost of such many subordinate mobile robots 1b, 1c, and 1d. As a means for solving the problem, a configuration of the subordinate mobile robot 2 that is remotely controlled with the main mobile robot 1 and can reduce the cost with a minimum necessary system structure is proposed in the second embodiment.
Operations in the case where the system is applied to different work at a workplace as shown in
The above system: has an effect of keeping the system cost low; but inversely has the disadvantages that the continuous remote control of the subordinate mobile robots 2a to 2c cannot be carried out, the separate operations are interrupted, and thus the environmental conditions of the separate operations are restricted considerably when the subordinate mobile robots 2a to 2c are located in a range not visible with the measurement means 11 in the main mobile robot 1, for example when a barrier exists between them.
In order to solve the above problems and reduce the system cost at the same time, the sixth embodiment sown in
In the present configuration, the travel control means 22 acquires information on a cumulative moving distance and a moving orientation in order to operate traveling with the drive mechanism 23. In the case of a differential drive mechanism for example, the numbers of the revolutions of the right and left drive wheels are measured with an encoder, the cumulative moving distance is estimated on the basis of the cumulative value counted with the encoder, and the moving orientation is estimated on the basis of the difference between the numbers of the revolutions of the right and left drive wheels or with a separately attached gyrosensor or the like.
The subordinate device position recognition means 100 estimates the position and the moving orientation of the subordinate mobile robot 2 itself on a map identical to the map acquired by the main mobile robot 1 on the basis of the information on the cumulative moving distance and the moving orientation acquired by the travel control means 22 and the predetermined initial travel conditions, namely the initial position and the initial orientation.
The travel planning means 101 receives individual travel plan data of the subordinate mobile robot 2 itself from the travel planning means 16 in the main mobile robot 1 and autonomously runs the subordinate mobile robot 2 on the basis of the self-position information acquired by the subordinate device position recognition means 100.
The main mobile robot 1, when it captures the subordinate mobile robot 2 by the measurement means 11, supplies data on the position and the moving orientation of the subordinate mobile robot 2 and time data on the time when the subordinate mobile robot 2 is captured through the communication means 12. The subordinate device position recognition means 100 receives the data on the position and the moving orientation of the subordinate mobile robot 2 through the communication means 21 and compensates the values of the position and the moving orientation of the subordinate mobile robot 2.
In the present embodiment, the position of the subordinate mobile robot 2 itself is estimated on the basis of the cumulative information acquired from the travel control means 22 and hence, in the case of long distance traveling or long time traveling, the accuracy in the estimation of the self-position deteriorates considerably due to slip in the drive mechanism 23, accumulation of measurement errors accompanying the increase of measurement time, or the like.
In order to solve the above problem, the subordinate device position recognition means 100 cancels the aforementioned cumulative error by using the data on the position and the moving orientation of the subordinate mobile robot 2 supplied from the main mobile robot 1 at a certain time as the true values in the initialization conditions. The cancellation is not always necessary and the increase of the error in the estimation of the self-position caused by the subordinate mobile robot 2 itself can be limited within a finite value even when the acquisition of the subordinate mobile robot 2 by the main mobile robot 1 is intermittent.
Examples of the operations in the present configuration are explained in reference to
In the operations shown in
In the operations shown in
By the present configuration, highly-accurate autonomous traveling can be realized with a low-cost subordinate mobile robot and the economic effect is large particularly when many subordinate mobile robots are operated in parallel.
In the sixth embodiment, the measurement means 11 is used for capturing subordinate mobile robots 2. On this occasion, when plural subordinate mobile robots 2 are operated as shown in the third embodiment, the possibility that the region visible with the measurement means 11 is shielded increases. Further, in the sixth embodiment, the subordinate mobile robots 2a to 2c are estimated and identified on the basis of the estimated positions respectively and thus it is possible to cause misidentification, for example, in the case where the subordinate mobile robots 2a to 2c travel closely to each other or another case.
In the configuration according to the seventh embodiment shown in
In the configuration according to the eighth embodiment shown in
By the present configuration, like the operation example shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-227812 | Sep 2007 | JP | national |
