Mobile robot system
The mobile robot system achieves cost-effective and precise arm positioning by using a guide and rotatable rollers to align the arm with the workpiece, addressing the challenges of positional accuracy and manufacturing costs.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KK TOSHIBA
- Filing Date
- 2022-01-14
- Publication Date
- 2026-06-10
Smart Images
Figure 0007872670000001 
Figure 0007872670000002 
Figure 0007872670000003
Abstract
Description
【Technical Field】 【0001】 Embodiments of the present invention relate to a mobile robot system. 【Background Art】 【0002】 In a mobile robot equipped with a handling robot on an unmanned vehicle, the mobile robot reads images of two marks attached to different corners of a workpiece by a sensor, detects the workpiece position from the two detected mark positions, and after performing position correction using the detected workpiece position, a technique for performing a handling operation on the workpiece is known. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 3-166072 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 Some types of mobile robots have an arm for transferring a workpiece to a gantry attached to the mobile robot. This type of mobile robot automatically positions itself near the gantry to transfer the workpiece, but there may be variations in the stop position of the mobile robot. Therefore, it is difficult to accurately position the arm with respect to the workpiece only with the information of the teaching position. 【0005】 Furthermore, as the size of the workpiece increases, the arm length of the robotic arm working on it also needs to increase, making it more difficult to accurately position the arm relative to the workpiece. This is because the attitude control of the mobile robot greatly affects the arm's positional deviation. Therefore, high-precision attitude control is required. In addition, since it is necessary to compensate for the positional deviations of the X, Y, and Θ axes, the mobile robot requires a multi-axis arm. In this case, it is necessary to improve the accuracy of the multi-axis arm control to accurately position the arm relative to the workpiece. Thus, because it is not easy to accurately position the arm of a mobile robot relative to a workpiece mounted on a stand, the manufacturing cost of mobile robot systems has been high. 【0006】 Embodiments of the present invention provide a low-cost mobile robot system for positioning relative to a workpiece. [Means for solving the problem] 【0007】 According to one embodiment, the mobile robot system comprises a mounting table and a mobile robot for transferring a workpiece placed on the mounting table. The mounting table has a guide consisting of an opening wider than a predetermined width and a body portion of the predetermined width. The mobile robot has an arm portion for transferring a workpiece placed on the mounting table, two or more rotatable rollers whose rotation axes are parallel to each other and arranged in a straight line along directions intersecting the directions in which the rotation axes extend, a movable portion that can move in all directions, and a control unit that drives the drive unit to move the mobile robot and causes at least two of the two or more rollers to be housed in the body portion of the guide. The guide is provided in a position where the arm portion can transfer a workpiece placed on the mounting table when the two or more guide rollers are housed in the body portion. [Brief explanation of the drawing] 【0008】 [Figure 1] A schematic diagram showing an example of the general configuration of a mobile robot system according to the first embodiment. [Figure 2] A perspective view showing an example of the external appearance of the frame according to the first embodiment. [Figure 3] A diagram showing an example of a part of the guide according to the first embodiment. [Figure 4] A perspective view showing an example of the appearance of a mobile robot according to the first embodiment. [Figure 5] A diagram illustrating an example of the arrangement of a Mecanum wheel according to the first embodiment. [Figure 6] A perspective view showing an example of the appearance of a Mecanum wheel according to the first embodiment. [Figure 7] A diagram showing an example of the contact point of a Mecanum wheel with respect to the mounting surface according to the first embodiment. [Figure 8] A diagram showing an example of the relationship between a typical wheel and its mounting surface. [Figure 9] A diagram showing an example of the arm portion according to the first embodiment, viewed from above. [Figure 10] A schematic cross-sectional view showing an example of the workpiece lifting operation according to the first embodiment. [Figure 11] A diagram showing an example of the side view of an omniwheel according to the first embodiment. [Figure 12] A diagram showing an example of the front view of an omniwheel according to the first embodiment. [Figure 13] A diagram showing an example of the guide roller according to the first embodiment being housed in the guide. [Figure 14] A diagram showing an example of the control configuration of a mobile robot according to the first embodiment. [Figure 15] A flowchart showing an example of the positioning process according to the first embodiment. [Figure 16] A schematic diagram showing an example of operation according to the first embodiment. [Figure 17] A schematic diagram showing an example of operation according to the first embodiment. [Figure 18] A diagram showing an example of the control configuration of a mobile robot according to the second embodiment. [Figure 19] A flowchart showing an example of the process for adjusting the direction of travel according to the second embodiment. [Figure 20]Schematic diagram showing an example of the operation according to the second embodiment. [Figure 21] Schematic diagram showing an example of the schematic configuration of the mobile robot system according to the third embodiment. 【Mode for Carrying Out the Invention】 【0009】 Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as those in reality. Even when representing the same part, the dimensions and ratios may be represented differently depending on the drawings. 【0010】 (First Embodiment) FIG. 1 is a schematic diagram showing an example of the schematic configuration of the mobile robot system 1. In the present embodiment, as shown in FIG. 1, the mobile robot system 1 is composed of a gantry 10 having a mounting table and a mobile robot 20. The gantry 10 is a table for mounting a workpiece W described later. The mobile robot 20 lifts up the workpiece W placed on the gantry 10 and mounts the workpiece W on another gantry 10. Further, the mobile robot 20 lifts up the workpiece W from another gantry 10, transports it, and mounts the workpiece W on the gantry 10. The gantry 10 has a guide 11 with a width D1 and an opening configured to be wide D2 (>D1). The mobile robot 20 has two rectangular parallelepiped units U1 and U2 on the traveling direction side. In the present embodiment, the direction in which the mobile robot 20 travels with respect to the gantry 10 is the X-axis, the direction perpendicular to the X-axis is the Y-axis, and the direction (angle) of the traveling direction of the mobile robot is the theta (Θ) direction. The paper surface direction in the drawing, that is, the height direction, is the Z-axis. Hereinafter, the gantry 10 and the mobile robot 20 will be described in detail. Also, in FIG. 1, a configuration in which two guide rollers R1 and R2 are provided is shown, but the number of guide rollers is not limited to two, and three or more may be provided so that their centers are arranged on a straight line. Hereinafter, more detailed specific examples of the gantry 10 and the mobile robot 20 of the mobile robot system 1 will be described. 【0011】 FIG. 2 is a perspective view showing an example of the appearance of the gantry 10. In this embodiment, the gantry 10 is provided with four steps in a rectangular parallelepiped frame. The upper three placement tables 10a, 10b, and 10c are placement tables for placing the work W. On each of the placement tables 10a, 10b, and 10c, tables for placing the work W are arranged side by side left and right, and two works W can be placed. Each of the tables of the placement tables 10a, 10b, and 10c is provided at the same position in the height direction of the gantry 10. In this embodiment, the gantry 10 having a plurality of placement tables will be described, but it may be a single placement table instead of the gantry 10. That is, the gantry 10 is an example of a placement table. In FIG. 2, a state where the work W is placed on each of the tables of the placement tables 10a, 10b, and 10c is shown. On the fourth step from the top, in other words, the lowermost step, positioning members 13 and 14 are provided. The positioning members 13 and 14 are members used to appropriately position the transfer robot 20 with respect to the gantry 10 when the transfer robot 20 transfers the work W to the gantry 10. Therefore, in this embodiment, two positioning members 13 and 14 are provided corresponding to each of the tables of the placement tables 10a, 10b, and 10c. The positioning members 13 and 14 are each formed by bending a rectangular plate material at the center. Further, the cross-section of the positioning members 13 and 14 is in an inverted V shape. Marks (positioning parts) 13a and 14a are provided on the positioning members 13 and 14. In this embodiment, the marks 13a and 14a are linear portions extending in the Z-axis direction corresponding to the bottom of the inverted V shape. Further, four legs 15 for supporting the gantry 10 are provided below the gantry 10. For this reason, a predetermined space is provided between the lower surface of the gantry 10 and the installation surface (for example, the floor surface). Two guides 11 and 12 are provided along the short side direction of the gantry 10 below the gantry 10. The opening of the guide 11 is provided on the side facing the transfer robot 20. Further, the guides 11 and 12 are provided at positions where the arm portion (described later) of the transfer robot 20 can transfer the work W placed on each of the tables of the placement tables 10a, 10b, and 10c of the gantry 10 when two or more of the following guide rollers R1 to R6 of the transfer robot 20 are accommodated in the guide 11. 【0012】 Figure 3 shows an example of a part of the guide 11. Note that Figure 3 shows a part of the back side of the frame 10 shown in Figure 2. As shown in Figure 3, the guide 11 consists of an opening 11a and a body 11b, and is fixed to the underside of the frame 10. The opening 11a has an opening width of width D2 (>D1), and this width gradually narrows from width D2 to width D1. The body 11b has a width D1 and is provided on the frame 10 in the short direction for a predetermined length. In this embodiment, the predetermined length is such that two or more guide rollers can all be housed when the mobile robot 20 is positioned on the frame 10 for transferring the workpiece W. Although not shown in the diagram, guide 12 has a similar configuration to guide 11 and is located on the underside of the frame 10. When two or more guide rollers R1 to R6 (described later) are housed within guide 12, guide 12 is fixed in a position that allows workpieces W placed on the other platforms 10a, 10b, and 10c of the frame 10 to be transferred. 【0013】 Figure 4 is a perspective view showing an example of the external appearance of the mobile robot 20. In this embodiment, the mobile robot 20 consists of a mobile robot body 30 and a tool unit 40. The mobile robot body 30 and the tool unit 40 may be configured as a single unit or connected to each other. In other words, it is sufficient that the mobile robot body 30 and the tool unit 40 can operate as a single unit. The mobile robot body 30 is roughly box-shaped and has a drive unit on its lower side. The drive unit drives the mobile robot 20, enabling it to move in all directions. Details of the drive unit will be described later. 【0014】 Next, a configuration that enables the mobile robot 20 to move in all directions will be described. In this embodiment, the mobile robot 20 is made movable in all directions by arranging Mecanum wheels as drive units at the four corners of the lower side of the mobile robot body 30. Figure 5 is a diagram illustrating an example of the arrangement of Mecanum wheels. As shown in Figure 5, two Mecanum wheels 31 are arranged on the lower part of one side of the mobile robot body 30. Although not shown in the diagram, two Mecanum wheels 31 are arranged on the lower part of the opposite side. In other words, a total of four Mecanum wheels 31 are arranged. More specifically, the Mecanum wheels 31 consist of right wheels and left wheels. Two right wheels are arranged on one diagonal, and two left wheels are arranged on the other diagonal. In the following, the four Mecanum wheels 31 may be collectively referred to as drive units. Figure 6 is a perspective view showing an example of the appearance of the Mecanum wheels 31. As shown in Figure 6, the Mecanum wheel 31 has an axle 32, and the outer circle 33 of the main body is rotatably attached to the axle 32. Eight barrel-shaped rollers 34 are mounted on the outer circle 33 of the main body. The directions in which the axis of rotation of each roller 34 extends are different from each other, and are inclined at 45 degrees with respect to the direction in which the axis of rotation of the axle 32 extends. Since the wheel is composed of eight barrel-shaped rollers in this way, the contact of the Mecanum wheel 31 with the mounting surface is a contact point C1, as shown in Figure 7. This contact point C1 is located on the bulging part of the barrel-shaped roller. Because contact with the mounting surface occurs only at the contact point C1, the four Mecanum wheels 31 can move forward and backward like ordinary wheels by transmitting driving force, and can also turn and move left and right by controlling the drive system. Here, Figure 8 shows an example of the relationship between an ordinary wheel T and a mounting surface. An ordinary wheel T is composed of a cylindrical shape with a donut-shaped cross-section, as shown in Figure 8(a). Therefore, as shown in Figure 8(b), the contact of the wheel T with the mounting surface is linear C2. Because the contact with the mounting surface is linear C2, turning is not easy. In contrast, the mobile robot body 30 uses four Mecanum wheels 31, which allows it to move in all directions, which is not easy when using a general wheel T.However, on the other hand, the mobile robot body 30 becomes more prone to slipping on the mounting surface compared to when using a general wheel T, and is more likely to perform tracking movements. In this embodiment, tracking movement refers to the fact that the contact point C1 between the Mecanum wheel 31 and the mounting surface becomes the contact point C1, causing the wheel to slip, and in addition, the mobile robot 20 to shake and become prone to slipping, making control difficult. 【0015】 Returning to Figure 4, the tool unit 40 will be described. The tool unit 40 comprises an arm support column 41, an electric Z-axis (electric unit) 42, a Z-axis guide 43, an arm 44, units U1 and U2, a roller base 47, guide rollers R1 to R6, a contact sensor (first sensor) 49, a laser range finder (detection unit) 50, and a stopper 51. The arm support column 41 consists of two columns that stand upright in the Z-axis direction with a predetermined distance between them. These two arm support columns 41 are connected by a plurality of rod-shaped members 41a. The mobile robot body 30 is fixed to the lower side of one of the surfaces formed by the arm support column 41 and the rod-shaped members 41a. The height of the arm support column 41 is determined according to the height of the mounting table 10c on which the workpiece W is placed. 【0016】 The electric Z-axis 42 is attached to the other side of the surface formed by the arm support column 41 and the rod-shaped member 41a. The electric Z-axis 42 has a rod-like shape with a rectangular cross-section. An arm portion 44 is attached to the electric Z-axis 42. Furthermore, the electric Z-axis 42 is equipped with a motor (not shown), and by rotating this motor, the arm portion 44 can be moved along the electric Z-axis 42 in the Z-axis direction. In this embodiment, a Z-axis guide 43 is provided along the Z-axis. This makes it possible to guide the movement of the arm portion 44 when the arm portion 44 moves in the Z-axis direction along the electric Z-axis 42. 【0017】 The arm section 44 includes an arm section support section 45, a first arm 46a, and a second arm 46b. The arm section support section 45 is attached to the electric Z-axis 42. The first arm 46a is attached to one end of the arm section support section 45, and the second arm 46b is attached to the other end. The arm section support section 45, the first arm 46a, and the second arm 46b may be formed as a single unit. The distance between the first arm 46a and the second arm 46b is determined by the width of the workpiece W to be transferred in the Y-axis direction. The first arm 46a and the second arm 46b are each configured to extend from the arm section support section 45 so as to be parallel to the installation surface on which the mobile robot system 1 is installed. 【0018】 Figure 9 shows an example of the arm portion 44 viewed from above. As shown in Figure 9, work guides WG are provided near the arm portion support portion 45 and near the tip portions of the first arm 46a and the second arm 46b, respectively. The work guides WG are used when transferring the workpiece W. Figure 10 is a schematic cross-sectional view showing an example of the action of lifting the workpiece W. As shown in Figure 10, the workpiece W placed on the mounting table 10a has projections on the left and right upper ends that protrude in the Y-axis direction. The cross-section of the work guide WG is a rectangular shape configured such that the inside of the arm portion 44 is the hypotenuse. When lifting the workpiece W, the hypotenuse portion of the work guide WG of the arm portion 44 fits under the projection of the workpiece W placed on the mounting portion 10a, and in this state, as the arm portion 44 moves upward in the Z-axis direction, the hypotenuse portion of the arm portion 44 comes into contact with the underside of the projection of the workpiece W, and the workpiece W is lifted from the mounting table 10a. Therefore, if the first arm 46a and the second arm 46b do not enter the workpiece W in the appropriate position in the left-right direction, the positional relationship between the workpiece guide WG and the protrusion of the workpiece W will be misaligned, making it impossible to lift the workpiece W. 【0019】 The first unit U1 and the second unit U2 are provided on the underside of the arm support column 41 and at both ends along the installation surface for a predetermined length. The first unit U1 and the second unit U2 prevent the mobile robot 20 from losing balance when the arm 44 transfers the workpiece W. Wheels are provided on the underside of the tips of the first unit U1 and the second unit U2. In this embodiment, these wheels are omniwheels. Figures 11 and 12 show examples of omniwheels 48a. Figure 11 shows an example of a side view of the omniwheel 48a. Figure 12 shows an example of a front view of the omniwheel 48a. In Figures 11 and 12, G indicates the contact surface. As shown in Figures 11 and 12, the omniwheel 48a can move freely in the vertical and horizontal directions due to the active rotation of the main body and the passive rotation of the rollers arranged on the outer circle of the main body. Therefore, the tool unit 40 operates in accordance with the drive of the Mecanum wheels 31 of the mobile robot body 30. As a result, the mobile robot 20 can rotate and move left and right, as described above, even with the tool unit 40. 【0020】 The first unit U1 is provided with a roller base 47. The roller base 47 is a plate-shaped member. In this embodiment, the roller base 47 is provided along the longitudinal direction of the first unit U1 and on the side of the second unit U2. At least two driven-rotatable guide rollers are arranged on the roller base 47 along its longitudinal direction, such that the centers of each guide roller are in a straight line. In this embodiment, as shown in Figure 4, six guide rollers R1 to R6 are provided, and the rotation axes of the guide rollers R1 to R6 are arranged parallel to each other and in a straight line along the direction in which the rotation axes extend. The diameter of each guide roller R1 to R6 is smaller than the width D1 of the body portion 11b of the guide 11 described above. Figure 13 shows an example of the state in which each guide roller R1 to R6 provided on the roller base 47 is housed in the guide 11. Figure 13 is also a view of the underside of the frame 10 from the side opposite to the side where the mobile robot 20 is located. The diagram shows the guide roller R1, which is mounted on the roller base 47, housed within the body portion 11b of the guide 11. 【0021】 A contact sensor 49 and a laser range finder 50 are provided on the underside of the arm support column 41 and between the first unit U1 and the second unit U2. The contact sensor 49 is a sensor that detects contact with the base 10. When contact with the base 10 is detected, the drive of the mobile robot body 30 is stopped. The laser range finder 50 performs processing such as irradiating a laser in a pulsed manner in multiple directions and receiving the reflected waves. Two stoppers 51 are provided on the underside of the arm support column 41. The stoppers 51 define the stopping position of the mobile robot 20 relative to the base 10. When the mobile robot 20 is positioned at this stopping position, the contact sensor 49 is configured to detect contact with the base 10. 【0022】 Figure 14 shows an example of the control configuration of the mobile robot 20. As shown in Figure 14, the mobile robot 20 has a control unit 110, a memory unit 120, a communication unit 130, a drive control unit 140, an arm drive control unit 150, a contact sensor 49, and a laser range finder 50. The drive control unit 140 includes a first drive control unit 141, a second drive control unit 142, a third drive control unit 143, and a fourth drive control unit 144. The first to fourth drive control units 141 to 144 are each connected to a Mecanum wheel 31. The arm drive control unit 150 is connected to an electric Z-axis 42. 【0023】 The control unit 110 includes a CPU, ROM, RAM, etc., and controls the workpiece transfer process of the mobile robot 20. The storage unit 120 is, for example, a hard disk drive (HDD) or a solid state drive (SSD), and stores various data and programs. In this embodiment, the various data stored include a 2D map showing the workspace where the frame 10 is installed, and the structure of the frame 10 (number of stages on the mounting platform, position where the workpiece W is placed, position of the marks, etc.). The program stored includes a program related to the transfer process of the workpiece W, for example, a program for executing the process of transferring the workpiece W from a predetermined position on frame 10 to a predetermined position on another frame 10. 【0024】 The communication unit 130 is a wireless communication unit that receives instructions from the outside. The mobile robot 20 starts the workpiece transfer process based on instructions received, for example, via the communication unit 130. 【0025】 The drive control unit 140 individually controls the drive of the Mecanum wheels 31 as described above. The Mecanum wheels 31 are located on the underside of the four corners of the mobile robot body 30 as described above, and each Mecanum wheel 31 is configured to be independently driveable by the first drive control unit 141 to the fourth drive control unit 144. Therefore, under the control of the control unit 110, the mobile robot 20 can move in all directions. 【0026】 The arm drive control unit 150 moves the arm 44 to a predetermined position in the Z-axis direction along the electric Z-axis 42 by driving a motor (not shown) of the electric Z-axis 42. The contact sensor 49 detects contact with the base 10. This detection result is transmitted to the control unit 110. The laser range finder 50 irradiates a laser in pulses in multiple directions and measures the distance to an object and its two-dimensional shape from the time it takes to receive the reflected waves. Based on the measurement results obtained in this way, the laser range finder 50 estimates the position of the mobile robot 20 on the 2D map. The estimation based on the measurement results also includes the positions of the marks 13a and 14a on the positioning members 13 and 14. This estimation result is transmitted to the control unit 110 as position information. 【0027】 Next, the processes performed by the mobile robot system 1 will be described with reference to Figure 15. Figure 15 is a flowchart showing an example of the process by which the mobile robot 20 positions itself relative to a workpiece W placed on a frame 10. The processes after positioning itself near another frame 10, or near a target frame 10 from an initial position, will be described. In this embodiment, the target position (hereinafter referred to as the target position) is such that the orientation of the mobile robot 20 is perpendicular to the longitudinal direction of the frame 10 (Y-axis direction), and at a predetermined distance from the end of the frame 10. In the following processes, the description will assume that the mobile robot 20 is positioned relative to the workpiece W placed on the mounting base 10a of the frame 10 by the guide 11. 【0028】 The mobile robot 20 is positioned at a target location relative to the frame 10. This movement to the target location is achieved by the control unit 110 executing a transfer program. The drive control unit 140 of the mobile robot body 30 drives the Mecanum wheels 31, and the mobile robot 20 is positioned at the target location according to a predetermined path. In this case, because the mobile robot 20 is driven by the Mecanum wheels 31, the contact point with the mounting surface is small, and tracking motion is likely to occur. Therefore, when the mobile robot 20 stops at the target location, a positional deviation and orientation deviation from the target location may occur. 【0029】 The control unit 110 receives position information estimated from the laser range finder 50 after the mobile robot 20 has stopped at the target position (ST101). 【0030】 Next, the control unit 110 determines whether the current position of the mobile robot 20 is the target position (ST102). In this embodiment, the control unit 110 determines whether the estimated position information of the mobile robot 20 matches the position information on a pre-specified 2D map. This allows the control unit 110 to confirm whether the current position is the target position. 【0031】 If it is determined that the target position is reached (ST102: YES), the control unit 110 determines whether the orientation of the mobile robot 20 is correct (ST103). In this embodiment, it is determined whether the orientation of the mobile robot 20 is perpendicular (Y-axis direction) to the longitudinal direction of the base 10. More specifically, the control unit 110 makes the determination based on the estimated position of mark 13a received from the laser range finder 50. This confirms that the orientation of the mobile robot 20 is accurate. In this embodiment, the configuration for determining the target position and orientation is described using the laser range finder 50, but it is not limited to this. For example, a separate sensor may be provided on the mobile robot 20 to determine the target position and orientation, and the detection results of this sensor may be used to determine the target position and orientation. 【0032】 If the control unit 110 determines that the position does not match (ST102:NO) or that the orientation does not match (ST103:NO), the control unit 110 corrects the misalignment of the mobile robot 20 (ST104). More specifically, the control unit 110 controls the drive unit control unit 140 so that the misalignment of the position and orientation become the target position and orientation. As a result, the mobile robot 20 is positioned at the target position and its orientation is correct. For example, this ensures that the alignment direction of the guide rollers R1 to R6 is included within the opening range of the guide 11 provided on the frame 10. 【0033】 If the control unit 110 determines that the mobile robot 20 is accurately positioned at the target location (ST103: YES), or if it corrects for any deviation (ST104), the control unit 110 controls the arm drive control unit 150 to move the arm 44 to a predetermined position in the Z-axis direction, according to the height on which the workpiece W to be transferred is placed (ST105). In order to pick up the workpiece W placed on the first stage mounting platform 10a of the frame 10, the arm 44 is moved to a height where the slanted edges of the workpiece guide WG of the first arm 46a and the slanted edges of the workpiece guide WG of the second arm 46b are positioned below the protrusions of the workpiece W. Next, the control unit 110 drives the drive unit (four Mecanum wheels 31) (ST106). Specifically, the control unit 110 moves the mobile robot 20 toward the frame 10. 【0034】 As a result, the mobile robot 20 approaches the side of the base 10. Even if the mobile robot 20 is misaligned or tilted relative to the base 10, as long as the guide roller R1 is positioned within the width D2 range, when the mobile robot 20 moves, the front-end guide roller R1 provided on the roller base 47 will come into contact with the inside of the opening of the guide 11, as schematically shown in Figure 16. Then, the guide roller R1 begins to rotate while being restricted to the inside of the opening 11a, and as the mobile robot 20 continues to move, the guide roller R1 is housed in the body portion 11b of the guide 11 along the inside of the opening 11a. Then, the second guide roller R2 comes into contact with the inside of the opening of the guide 11 and, like the first guide roller R1, is housed in the body portion 11b of the guide 11. In this way, as schematically shown in Figure 17, the multiple guide rollers R1 to R6 provided on the roller base 47 are housed in the body portion 11b of the guide 11. In other words, as the guide rollers R1 to R6 are sequentially housed in the body portion 11b, the direction of travel of the mobile robot body 30 is restricted to align with the X-axis direction, so that the Θ direction indicating the orientation of the mobile robot body 30 aligns with the X-axis direction. As a result, even if the mobile robot body 30 deviates from the target position due to tracing motion when approaching the stand 10, it can still move towards the target position and direction. In this embodiment, the case in which all of the guide rollers R1 to R6 are housed in the body portion 11b is described, but it is sufficient if at least two or more guide rollers are housed in the body portion 11b. 【0035】 Next, the control unit 110 determines whether the mobile robot 20 has moved to a predetermined position (ST107). In this embodiment, the control unit 110 determines whether it has moved to a predetermined position based on the signal transmitted from the contact sensor 49. For example, if an OFF signal is received from the contact sensor 49, it is determined that the robot has not moved to the predetermined position, and if an ON signal is received, it is determined that the robot has moved to the predetermined position. Here, the predetermined position is the position where the four work guides WG provided on the arm portion 44 coincide with the protrusions of the workpiece W in the Z-axis direction. If it is determined that the robot has not moved to the predetermined position (ST107: NO), the control unit 110 continues the movement of the mobile robot 20. 【0036】 If it is determined that the robot has moved to the predetermined position (ST107: YES), the control unit 110 stops the drive of the drive unit (ST108). As a result, the mobile robot 20 stops. At this time, since the centers of the multiple guide rollers R1 to R6 are aligned in a straight line, the mobile robot 20 is precisely positioned relative to the frame 10. That is, the two work guides WG of the first arm 46a are located to the right of the workpiece W as seen from the mobile robot 20, and below the protruding portion, while the two work guides WG of the second arm 46b are located to the left of the workpiece W as seen from the mobile robot 20, and below the protruding portion. 【0037】 Next, the control unit 110 controls the arm drive control unit 150 to move the arm 44 upward (in the Z-axis direction) (ST109). The amount of movement of the arm 44 at this time is at least enough to lift the workpiece W off the mounting table 10a. As a result, the workpiece W is picked up from the mounting table 10a. Next, the mobile robot 20 drives the drive unit (ST110). Specifically, after the control unit 110 performs an action to disengage from the frame 10, the mobile robot 20 moves to the target position on the next frame 10 on which the workpiece W, which has been picked up from the current position, will be placed. The subsequent processing is the same as the processing from steps ST101 to ST110 described above, except that the workpiece W is placed on the frame instead of being picked up. 【0038】 In the mobile robot system 1 configured as described above, the guide 11 or guide 12 of the frame 10 is positioned so that when the guide rollers R1 to R6 are housed in the body portion 11b of the guide 11 or the body portion 12b of the guide 12, the arm portion 44 can transfer the workpiece W placed on the mounting tables 10a, 10b, and 10c of the frame 10. Therefore, in the mobile robot system 1, the arm portion 44 of the mobile robot 20 can be accurately positioned relative to the workpiece W placed on the frame 10 with a simple configuration, and the cost of positioning can be reduced. If a multi-axis robot arm were provided in the tool portion 40 to correct the misalignment in the three axes (X-axis, Y-axis, and Θ-axis), the mobile robot system 1 would be expensive. However, in this embodiment, accurate positioning is possible, so the three-axis misalignment can be prevented, and a multi-axis robot arm is not required. 【0039】 Furthermore, in the mobile robot system 1, when the mobile robot 20 moves along the inside of the opening of the guide 11, for example, since the drive unit of the mobile robot 20 uses Mecanum wheels 31, contact with the installation surface is reduced, and movement while being restricted becomes smoother. 【0040】 Furthermore, although the above embodiment described a case in which six guide rollers R1 to R6 are provided on the roller base 47, the number of guide rollers is not limited to this, and at least two or more guide rollers can be provided, and the centers of these two or more guide rollers should be aligned in a straight line. Also, when only two guide rollers are provided, it is desirable to specify the distance between the guide rollers such that, for example, when the two guide rollers are housed in the body portion 11b, the guide rollers are located at both ends of the body portion 11b. By widening the distance between the guide rollers in this way, the positioning accuracy of the arm portion 44 relative to the workpiece W placed on the frame 10 can be improved even when only two guide rollers are provided. 【0041】 (Second Embodiment) This second embodiment differs from the first embodiment in that it performs control to adjust the direction of movement of the mobile robot within the guide when the guide roller is moved within the guide. Therefore, this control will be described in detail below. Components identical to those in the first embodiment are denoted by the same reference numerals, and their descriptions will be omitted. In this embodiment, for the sake of simplicity, the description will be given in the case where one guide 11 is provided on the frame 10 and two guide rollers are provided on the unit U1. 【0042】 Figure 18 shows an example of the control configuration of the mobile robot 20 of this embodiment. As shown in Figure 18, the mobile robot 20 has two-axis force sensors (second sensors) 161 and 162 added to the configuration of the mobile robot 20 shown in Figure 14 described above. Two-axis force sensor 161 is provided on guide roller R1, and two-axis force sensor 162 is provided on guide roller R2. Two-axis force sensors 161 and 162 detect forces in the direction of travel (X-axis direction) and the lateral direction (Y-axis direction). The two-axis forces detected in this way are output to the control unit 110. In this embodiment, the case where two-axis force sensors 161 and 162 are used is described, but any sensor capable of detecting forces in the Y-axis direction may be used. 【0043】 Figure 19 is a flowchart showing an example of the process for adjusting the direction of travel. As shown in Figure 19, the control unit 110 determines whether or not it is inside the guide 11 (ST201). The control unit 110 can determine whether or not it is traveling inside the guide 11 based, for example, on the distance traveled from the target position described above, the time taken, and the estimated position information. If it is determined that it is inside the guide 11 (ST201: YES), the control unit 110 executes the following process. In this embodiment, the explanation is given in the case of determining whether or not it is inside the guide 11, but it may also be configured to execute the following process when the output of force in the Y-axis direction is detected by the two-axis force sensors 161 and 162. 【0044】 Next, the control unit 110 drives the drive unit (four Mecanum wheels 31) (ST202). As a result, the control unit 110 continues the process of moving the mobile robot 20 in the direction of travel at a travel speed Vx. While the mobile robot 20 is moving, the control unit 110 receives outputs from two two-axis force sensors 161 and 162 (ST203). 【0045】 Next, the control unit 110 calculates the force component in the Y-axis direction from the received output and sets the calculated velocity component as the driving speed of the drive unit so that it is in the opposite direction to the force component in the Y-axis direction, and sets the moving speed Vx in the X-axis direction (ST204). For example, as shown in the schematic diagram of Figure 20, when the mobile robot 20 is moving in the X-axis direction indicated by arrow A1, and a force in the Y-axis direction indicated by arrow A2 (left side in the figure) and arrow A3 (left side in the figure) is applied to the guide roller R1, the speed is set so that the mobile robot 20 moves to the left so that this force is not applied. As a result, the direction of movement of the mobile robot 20 is adjusted so that it moves in the opposite direction to the direction in which the force was applied in the Y-axis direction. 【0046】 Next, the control unit 110 determines whether the contact sensor 49 has detected the base 10 (ST205). If the control unit 110 determines that the contact sensor 49 has not detected the base 10 (ST205: NO), the control unit 110 executes the processes of steps ST203 and ST204 described above. As a result, the process of adjusting the direction of travel continues until the contact sensor 49 detects the base 10, in other words, while the mobile robot 20 is moving in the direction of travel. On the other hand, if the contact sensor 49 determines that the base 10 has been detected (ST205: YES), the control unit 110 stops the drive of the drive unit (ST206). 【0047】 According to this second embodiment, when the guide rollers R1 and R2 of the mobile robot 20 move within the guide 11, the direction of movement of the mobile robot 20 can be adjusted. Since the mobile robot 20 uses Mecanum wheels 31, as previously described, the contact point C1 with the mounting surface of the frame 10 is small, and it may slip and perform a tracing motion. In this embodiment, the direction of movement is adjusted so that the mobile robot 20 moves straight in the direction of movement within the guide 11, thereby reducing the amount of movement of the tracing motion of the mobile robot 20. This reduces the time during which friction occurs between the Mecanum wheels 31 and the mounting surface, and improves the lifespan of the Mecanum wheels 31. 【0048】 (Third embodiment) This third embodiment differs from the first embodiment in that it specifies the size of the guide opening. Therefore, matters related to the size of the guide opening will be described in detail below. Components identical to those in the first embodiment are denoted by the same reference numerals, and their descriptions will be omitted. In this embodiment as well, similar to the second embodiment, in order to simplify the explanation, the case in which one guide 11 is provided on the frame 10 and two guide rollers are provided on the unit U1 will be described. 【0049】 Figure 21 is a schematic diagram showing an example of the general configuration of the mobile robot system 1. As shown in Figure 21, the mobile robot system 1 comprises a frame 10 equipped with a guide 11, and a mobile robot 20 having a unit U1 and a unit U2, which are provided with guide rollers R1 and R2, facing the frame 10. The guide 11 has an opening 11a and a body portion 11b. The width of the body portion is width D1, and the width of the opening of the opening 11a is D2 (>D1), as in the first embodiment. In this embodiment, the distance of width D2 is defined as follows. 【0050】 The mobile robot 20 estimates its position on a 2D map based on calculation results from the laser range finder 50 and moves from a predetermined position to a target position. When positioned at this target position, it may not be able to stop precisely at the target position as described above. Thus, since the mobile robot 20 may experience deviation when stopping, in this embodiment, the width D2 of the opening of the guide 11 is set to a width sufficient to absorb the error caused by this deviation. Specifically, the width D2 should be determined based on the positioning accuracy of the mobile robot 20 to the target position, the frictional force between the Mecanum wheel 31 and the mounting surface, and the weight of the workpiece W placed on the arm 44. 【0051】 When the mobile robot 20 stops at the target position, even if there is a misalignment in the left-right direction, for example as shown by the double arrow A4 in Figure 21, the width D2 of the opening of the guide 11 is configured to absorb the error of the misalignment, so the guide roller R1 comes into contact with the inner surface of the opening of the guide 11. Then, as the guide roller R1 rotates, it is housed along the inside of the opening 11a into the body portion 11b. Similarly, as the mobile robot 20 moves, the next guide roller R2 is also housed along the inside of the opening 11a into the body portion 11b, just like the first guide roller R1. As a result, the guide rollers R1 and R2 are housed in the body portion 11b, and the mobile robot 20 is positioned relative to the workpiece W placed on the frame 20. 【0052】 According to this third embodiment, the opening of the guide 11 is set to a width D2 so that the mobile robot system 1 can absorb the displacement when the mobile robot 20 stops at the target position. Therefore, there is no need to perform a process to correct the displacement when the mobile robot 20 stops. Accordingly, for example, the process of adjusting the displacement when positioned at the target position in the first embodiment (steps ST102 to ST104) can be omitted, and the transfer process of the workpiece W in the mobile robot system 1 can be expedited. 【0053】 In the above embodiment, the configuration described shows the guide rollers R1 to R6 mounted on the roller base 47, but this is not the only configuration. For example, they may be mounted directly on unit U1. Also, the roller base 47 may be mounted on unit U2 instead of unit U1. Furthermore, the arrangement of the guide 11, guide 12, and guide rollers R1 to R6 can be arbitrarily set as long as the arm portion 44 can be positioned to transfer the workpiece W when the guide rollers R1 to R6 are housed in the body portions 11b and 12b of the guide 11. 【0054】 Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols] 【0055】 1...Mobile robot system, 10...Stand, 11...Guide, 11a...Opening, 11...Body section, 12...Guide, 12a...Opening, 12b...Body section, 20...Mobile robot, 30...Mobile robot body, 31...Mecanum wheel, 40...Tool section, 44...Arm section, 45...Arm support section, 46a...First arm, 46b...Second arm, 47...Roller base, 48a,48b...Omni-wheel, 49...Contact sensor, 50...Laser range finder, 110...Drive control unit, 161,162...2-axis force sensor, C1...Contact point, C2...Contact surface, D1,D2...Width, R1~R6...Guide roller, R1a,R2a...Center of guide roller, W...Workpiece, WG...Workpiece guide
Claims
[Claim 1] A platform on which an object can be placed, A mobile robot that handles the object between itself and the aforementioned platform, Equipped with, The aforementioned stand is The device has an opening that is wider than a predetermined width, and a guide consisting of a body portion of the predetermined width. The aforementioned mobile robot A mobile robot body equipped with a drive unit, An arm portion extending in one direction from the mobile robot body and handling the object between itself and the platform, An extending portion extending from the mobile robot body in one direction, provided with a plurality of rotatable rollers whose rotation axes are parallel to each other and arranged in a straight line along a direction intersecting the direction in which the rotation axes extend, A control unit that drives the drive unit to move the mobile robot and houses at least two of the plurality of rollers within the body portion of the guide, It has, A mobile robot system wherein the guide is positioned so that the arm can handle the object between itself and the base when the two or more rollers are housed in the body portion. [Claim 2] The mobile robot system according to Claim 1, wherein the arm portion of the mobile robot moves the object to a predetermined position on the platform. [Claim 3] The mobile robot system according to claim 1 or 2, wherein the drive unit is movable in all directions. [Claim 4] The roller has a second sensor used to determine the force in at least the width direction of the guide, When the mobile robot moves its torso, the control unit sets the speed such that the mobile robot moves in the opposite direction to the force detected by the second sensor in the width direction. A mobile robot system according to any one of claims 1 to 3. [Claim 5] A platform on which an object can be placed, A mobile robot for transferring the object placed on the aforementioned platform, A mobile robot system comprising, The aforementioned stand is The device has an opening that is wider than a predetermined width, and a guide consisting of a body portion of the predetermined width. The aforementioned mobile robot An arm portion for transferring the object placed on the aforementioned stand, Two or more rotatable rollers, each with a rotation axis parallel to the other and arranged in a straight line along a direction intersecting the direction in which each rotation axis extends, A drive unit that can move in all directions, A control unit that drives the drive unit to move the mobile robot and houses at least two of the two or more rollers within the body portion of the guide, It has, The guide is provided in a position where the arm portion can move the object placed on the predetermined position of the base when the two or more rollers are housed in the body portion. The roller has a second sensor used to determine the force in at least the width direction of the guide, The control unit sets the speed such that when the mobile robot moves its body portion, the mobile robot moves in the opposite direction to the widthwise force detected by the second sensor. [Claim 6] The aforementioned stand further has legs that support the stand, The aforementioned guide is provided on the lower side of the base, A mobile robot system according to any one of claims 1 to 5. [Claim 7] The mobile robot further includes a first sensor for detecting the stopping position of the mobile robot relative to the platform, When the control unit detects the stop position using the first sensor, it stops the operation of the drive unit. A mobile robot system according to any one of claims 1 to 6. [Claim 8] The mobile robot further includes a stopper that defines the stopping position of the mobile robot relative to the base. A mobile robot system according to any one of claims 1 to 7. [Claim 9] The drive unit has four Mecanum wheels, each composed of multiple barrel-shaped rollers. A mobile robot system according to any one of claims 1 to 8. [Claim 10] The width of the opening of the guide is determined based on the position and orientation deviation of the mobile robot when the mobile robot stops at the target position. A mobile robot system according to any one of claims 1 to 8. [Claim 11] The base further includes a positioning portion provided near the opening of the guide, The mobile robot further includes a detection unit for detecting the positioning unit, The control unit adjusts the position and orientation deviation of the mobile robot based on the positioning unit detected by the detection unit. A mobile robot system according to any one of claims 1 to 10. [Claim 12] The mobile robot system according to any one of claims 1 to 11, further comprising an electric unit for moving the arm portion in a vertical direction.