Moving body

Abstract

To provide a moving body that can obtain a self-location thereof, with a simple structure.SOLUTION: A moving body 1 is provided with: a hand part 11 having a magnet; a robot 12 that moves the hand part 11; a force sensor 13 for obtaining force acting on the hand part 11; a moving carrier 15 having a moving mechanism 14, to which a base end of the robot 12 is fixed; a robot control part 16 that controls the robot 12 so that the hand part 11 is moved; a storing part 17 that stores association information for associating a relative location of the hand part 11 with respect to a reference magnet 20 with the force acting on the hand part 11; a self-location obtaining part 18 that obtains a self-location of the moving body 1, using force acting on the hand part 11 existing at two or more different locations and the association information; and a movement control part 19 that controls the moving mechanism 14, using the self-location. This constitution enables the self-location to be obtained with a simple structure using the magnet.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a moving body having a robot for moving a hand part.

Background Art

[0002] Conventionally, there has been known a moving body that performs alignment to a reference position using information acquired by a laser range sensor or an image sensor (see Patent Document 1). Further, in a robot that can be transported by an automated guided vehicle, highly accurate positioning is performed by inserting a positioning pin into a hole provided on the floor surface (see Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, alignment using a laser range sensor or an image sensor has a problem of being easily affected by lighting or the like. For example, in a place with many reflectors, it is difficult to perform alignment using a laser range sensor, and in a dark place, it is difficult to perform alignment using an image sensor.

[0005] Further, when a gantry cannot be used, the method described in Patent Document 2 cannot be used. Further, in the method described in Patent Document 2, it is necessary to prepare a special gantry or provide positioning holes on the floor surface, and there is also a problem that the cost for that is high.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a moving body that can acquire its own position without using a laser range sensor, an image sensor, or a gantry.

Means for Solving the Problems

[0007] To achieve the above object, a moving body according to an aspect of the present invention is a moving body having a hand portion having a magnet, a robot for moving the hand portion, a force sensor for acquiring a force applied to the hand portion, and a moving mechanism for moving the moving body. The moving body includes a mobile cart to which the base end side of the robot is fixed, a robot control unit that moves the hand portion by controlling the robot, a storage unit that stores two or more pieces of correspondence information associating the relative position of the hand portion with respect to a reference magnet, which is a magnet arranged at a predetermined position in the moving environment of the moving body, and the force applied to the hand portion existing at the relative position, a self-position acquisition unit that acquires the self-position of the moving body using the force applied to the hand portion existing at two or more different positions acquired using the force sensor and the two or more pieces of correspondence information, and a movement control unit that controls the movement mechanism using the self-position acquired by the self-position acquisition unit.

Effects of the Invention

[0008] According to the moving body according to an aspect of the present invention, the self-position of the moving body can be acquired by acquiring the force applied to the hand portion by the reference magnet. Therefore, for example, it becomes possible to perform positioning with respect to the reference magnet without using a laser range sensor, an image sensor, or a gantry.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiment for Carrying out the Invention

[0010] Hereinafter, the mobile body according to the present invention will be described using embodiments. In the following embodiments, components and steps with the same reference numerals are the same or corresponding, and repeated descriptions may be omitted. The mobile body according to the present embodiment obtains the self-position of the mobile body by obtaining the force applied to the hand unit by the magnetic force between the magnet of the hand unit and the reference magnet arranged in the moving environment of the mobile body.

[0011] FIG. 1 is an external schematic view showing the configuration of the mobile body 1 according to the present embodiment, and FIG. 2 is a functional block diagram showing the configuration of the mobile body 1. The mobile body 1 includes a hand unit 11, a robot 12 for moving the hand unit 11, a force sensor 13 for obtaining the force applied to the hand unit 11, a mobile cart 15 for moving the robot 12, a robot control unit 16 for controlling the robot 12, a storage unit 17 in which two or more pieces of corresponding information are stored, a self-position acquisition unit 18 for obtaining the self-position of the mobile body 1 using the force applied to the hand unit 11 and the corresponding information, and a movement control unit 19 for controlling the movement of the mobile body 1 using the self-position. The mobile cart 15 has a movement mechanism 14 for moving the mobile body 1. The use of the mobile body 1 is not particularly limited, but the mobile body 1 may be, for example, a mobile body for carrying, or a mobile body for other uses such as security and cleaning. As an example, the mobile body 1 may move autonomously.

[0012] A reference magnet 20 is arranged at a predetermined position in the moving environment of the moving body 1. The reference magnet 20 is a magnet serving as a reference for the moving body 1 to acquire its own position. The arrangement position of the reference magnet 20 may be determined in advance. In the present embodiment, as shown in FIG. 1, the case where the reference magnet 20 is attached to a shelf 21 will be mainly described. However, the reference magnet 20 may be arranged on an object other than the shelf, or on a wall, ceiling, floor, etc. It is preferable that no other magnet exists within the range affected by the magnetic force of the reference magnet 20. The reference magnet 20 may be, for example, a permanent magnet or an electromagnet. In the present embodiment, the case where the reference magnet 20 is a permanent magnet will be mainly described.

[0013] The hand portion 11 has a magnet. This magnet may be, for example, an electromagnet or a permanent magnet. In the present embodiment, the case where the magnet possessed by the hand portion 11 is an electromagnet will be mainly described. The hand portion 11 may have a function corresponding to the work performed by a robot 12 such as a holding mechanism for holding an object. The holding mechanism may be, for example, a gripping portion capable of gripping an object, an electromagnet capable of magnetically attaching an object, a vacuum suction means capable of sucking an object, etc.

[0014] The robot 12 moves the hand portion 11. The hand portion 11 may be attached to the tip of the robot 12 as shown in FIG. 1. The robot 12 may be, for example, a robot having a plurality of arms connected by joints driven by a motor. This robot may be, for example, a vertical articulated robot or a horizontal articulated robot. Also, the robot 12 may be, for example, an orthogonal robot having a plurality of linear axes combined at right angles. The robot 12 may be, for example, for transporting an object to be transported, for performing an assembly operation, or for performing other operations. Also, the base end side of the robot 12 is fixed to a movable carriage 15. Therefore, the robot 12 is movable.

[0015] The force sensor 13 is for acquiring the force applied to the hand unit 11. The force sensor 13 may be provided, for example, between the tip of the robot 12 and the hand unit 11 as shown in FIG. 1. The force sensor 13 may be, for example, a three-axis force sensor or a six-axis force sensor. The force measured by the force sensor 13, that is, the measured value of the force sensor 13, usually becomes a force including the gravity applied to the hand unit 11. The force applied to the hand unit 11 acquired using the force sensor 13 may be, for example, a force including gravity, that is, the measured value of the force sensor 13. In this case, the force applied to the hand unit 11 used when acquiring the self-position can be easily acquired.

[0016] Also, the force applied to the hand unit 11 acquired by the force sensor 13 may be, for example, the force applied to the hand unit 11 by the reference magnet 20, that is, the force acting between the reference magnet 20 and the magnet of the hand unit 11 excluding the influence of gravity. In this case, for example, the measured value of the force sensor 13 is acquired at a position where the influence of the magnetic force of the reference magnet 20 does not reach, and the measured value of the force sensor 13 is acquired at a position where the influence of the magnetic force of the reference magnet 20 reaches. By calculating the difference between the two measured values, the force applied to the hand unit 11 by the reference magnet 20 may be acquired. In this case, the weight of the hand unit 11 used when estimating the self-position does not have to be the same as the weight of the hand unit 11 used when generating the corresponding information. That is, different hand units 11 can also be used when estimating the self-position and when generating the corresponding information. However, it is preferable that the magnets of the different hand units 11 have the same configuration. When the measured values of the force sensor 13 are measured at positions where the influence of the magnetic force of the reference magnet 20 reaches and does not reach, it is preferable that the posture of the hand unit 11 is the same. This is to make the gravity applied to the hand unit 11 measured by the force sensor 13 the same at both positions.

[0017] When obtaining the force applied to the hand part 11, it is preferable that the relative posture of the magnet of the hand part 11 with respect to the reference magnet 20 is constant. Therefore, for example, when obtaining the force applied to the hand part 11, the posture of the magnet of the hand part 11 may be set to a posture determined in advance in the world coordinate system. This is because when the posture of the magnet changes, the force applied to the hand part 11 also changes. Therefore, when performing measurement by the force sensor 13, for example, the posture of the hand part 11 may be controlled so that the azimuth angle and elevation angle of the magnet of the hand part 11 in the world coordinate system are set to predetermined values. To perform such control, the moving body 1 may have sensors capable of specifying the azimuth angle and elevation angle in the world coordinate system, for example, an azimuth angle sensor or an inclination sensor. When the floor surface in the moving environment of the moving body 1 is horizontal, since the horizontal plane can be specified in the moving body 1, the moving body 1 may not have an inclination sensor. The azimuth angle sensor may be, for example, an electronic compass that obtains the azimuth angle using geomagnetism, or a sensor that obtains the azimuth angle with respect to the reference direction based on the integrated value of the angular velocity sensor. Also, the acquisition of the force applied to the hand part 11 by the reference magnet 20 may be performed by, for example, the self-position acquisition unit 18. In the present embodiment, the case where the force applied to the hand part 11 is the measured value of the force sensor 13 will be mainly described.

[0018] The mobile cart 15 is a cart for moving the robot 12. As shown in FIG. 1, the proximal end side of the robot 12 is fixed to the mobile cart 15. The mobile cart 15 has a moving mechanism 14 for moving the moving body 1. The moving mechanism 14 may be, for example, one that causes the moving body 1 to travel on the floor surface. As an example, the moving mechanism 14 may have a traveling part such as wheels and a driving means such as a motor or an engine that drives the traveling part.

[0019] The robot control unit 16 moves the hand unit 11 by controlling the robot 12. The robot control unit 16 may control the robot 12 so that, for example, a predetermined process such as conveyance or assembly is performed by the hand unit 11. Further, the robot control unit 16 may control the robot 12 to move the hand unit 11 to a desired position and posture while the mobile cart 15 is stopped, for example, in order to acquire its own position using the force applied to the hand unit 11. Further, the robot control unit 16 may switch the on and off of the electromagnet by switching the energization and non-energization of the electromagnet provided in the hand unit 11, for example. Further, the robot control unit 16 may switch the on and off of the electromagnet when the reference magnet 20 is an electromagnet, for example.

[0020] In the storage unit 17, two or more pieces of correspondence information are stored. The correspondence information may be information that associates the relative position of the hand unit 11 with respect to the reference magnet 20, which is a magnet arranged at a predetermined position in the movement environment of the moving body 1, and the force applied to the hand unit 11 existing at that relative position. The force applied to the hand unit 11 may be acquired using the force sensor 13, for example. The relative position of the hand unit 11 with respect to the reference magnet 20 may be, for example, the position in the local coordinate system of the reference magnet 20 or the position in the world coordinate system. FIG. 3 is a diagram showing an example of a plurality of pieces of correspondence information. As shown in FIG. 3, the correspondence information may be information having the relative position with respect to the reference magnet 20 and the force applied to the hand unit 11 existing at that position. Note that, as described above, the posture of the hand unit 11 existing at that position may be determined in advance. In the first piece of correspondence information in FIG. 3, it is shown that the force applied to the hand unit 11 existing at the position (x001, y001, z001) is (A001, B001, C001). Note that the position and the force may be, for example, the coordinate values (x001, y001, z001) indicating the position in a predetermined coordinate system and the vector (A001, B001, C001) indicating the magnitude and direction of the force.

[0021] For example, when the force applied to the hand unit 11 obtained using the force sensor 13 is the measured value of the force sensor 13, the force associated with the position in the correspondence information may also be measured by the hand unit 11 in a predetermined posture. Note that the force associated with the position in the correspondence information may be measured, for example, by the hand unit 11 of the moving body 1 or by another hand unit having a similar configuration.

[0022] Note that only the correspondence information regarding the range of the predetermined position may be stored in the storage unit 17. For example, when only the force applied to the hand unit 11 located at a predetermined height from the floor surface is to be acquired, the position associated with the force applied to the hand unit 11 in the plurality of correspondence information stored in the storage unit 17 may be only the position at the predetermined height.

[0023] The process by which two or more pieces of correspondence information are stored in the storage unit 17 is not limited. For example, two or more pieces of correspondence information may be stored in the storage unit 17 via a recording medium, two or more pieces of correspondence information transmitted via a communication line or the like may be stored in the storage unit 17, or two or more pieces of correspondence information input via an input device may be stored in the storage unit 17. The storage unit 17 is preferably realized by a non-volatile recording medium, but may also be realized by a volatile recording medium. The recording medium may be, for example, a semiconductor memory, a magnetic disk, an optical disk, or the like.

[0024] The self-position acquisition unit 18 acquires the self-position of the mobile body 1 by using the forces applied to the hand units 11 existing at two or more different positions, which are acquired using the force sensor 13, and two or more pieces of corresponding information stored in the storage unit 17. Note that a predetermined magnetic field is formed around the reference magnet 20 by the reference magnet 20. Also, the forces applied to the hand unit 11 when the magnet possessed by the hand unit 11 is positioned in the magnetic field are recorded for each position as a plurality of pieces of corresponding information. Therefore, when the force applied to the hand unit 11 existing at a certain position is acquired, the position of the hand unit 11 can be specified by using a plurality of pieces of corresponding information. Also, since the position of the hand unit 11 in the local coordinate system of the mobile body 1 is known, the position of the mobile body 1 can be specified by using the position of the hand unit 11. In this way, the self-position acquisition unit 18 can acquire the self-position of the mobile body 1 by using the force applied to the hand unit 11.

[0025] Note that the magnetic field lines generated by the reference magnet 20 are generally considered to have symmetry. Therefore, when the self-position of the mobile body 1 is acquired using only the force applied to the hand unit 11 existing at one position, it is considered that the error will increase. Thus, it is preferable to acquire the self-position of the mobile body 1 by using the forces applied to the hand units 11 existing at two or more different positions. Note that the relative positional relationship between two or more different positions of the hand unit 11 is assumed to be known. That is, the self-position acquisition unit 18 may acquire the self-position of the mobile body 1 by using the forces applied to the hand units 11 existing at two or more different positions with a known relative positional relationship and two or more pieces of corresponding information. This self-position may be, for example, the position in the local coordinate system of the reference magnet 20. Note that, for example, when the relative positional relationship between the local coordinate system of the reference magnet 20 and the world coordinate system is known, the self-position may be the position in the world coordinate system. Also, the self-position preferably generally includes the orientation (direction) of the mobile body 1. The orientation of the mobile body 1 may be indicated, for example, by an azimuth angle or the like with respect to a specific direction in the coordinate system.

[0026] Two or more different positions of the hand part 11 may be, for example, two or more different positions of the hand part 11 moved by the robot 12 when the mobile cart 15 is stopped. In this case, the self-position acquisition unit 18 can acquire the self-position of the moving body 1, for example, when the mobile cart 15 is stopped. Also, in this case, for example, based on two or more different positions of the hand part 11 in the local coordinate system of the robot 12 (hereinafter, may also be referred to as the "robot coordinate system") obtained by forward kinematics using the angles of the respective joints of the robot 12, the relative positional relationship between the two or more different positions may be acquired.

[0027] Also, two or more different positions of the hand part 11 may be, for example, two or more different positions of the hand part 11 moved by the mobile cart 15. In this case, the self-position of the moving body 1 can be acquired according to the movement by the mobile cart 15. Also, in this case, for example, based on the movement distance corresponding to the number of rotations of the wheels acquired by an encoder or the like provided in the movement mechanism 14 of the mobile cart 15, the relative positional relationship between the two or more different positions may be acquired. That is, the relative positional relationship may be acquired by odometry. In this case, the self-position acquisition unit 18 may acquire, for example, the self-position of the moving body 1 after movement, that is, the current self-position.

[0028] Also, two or more different positions of the hand part 11 may be, for example, two or more different positions of the hand part 11 moved by both the mobile cart 15 and the robot 12. In this case, for example, using the position of the hand part 11 in the robot coordinate system and the relative positional relationship of the mobile cart 15 acquired by odometry, the relative positional relationship between the two or more different positions may be acquired.

[0029] The self-position acquisition unit 18 may identify the position in a predetermined coordinate system (e.g., the local coordinate system of the reference magnet 20 or the world coordinate system, etc.) where the forces applied to the hand units 11 existing at two or more different positions fit, for example, by using two or more pieces of correspondence information. In this way, the self-position acquisition unit 18 can identify the position of the hand unit 11. Further, the self-position acquisition unit 18 may receive, for example, from the robot control unit 16, the position of the hand unit 11 in the robot coordinate system, and use the position of the hand unit 11 in the robot coordinate system, the position of the hand unit 11 in the predetermined coordinate system, and the position of the robot 12 in the local coordinate system of the moving body 1 to acquire the self-position, which is the position of the moving body 1 in the predetermined coordinate system.

[0030] In the acquisition of the self-position using two or more pieces of correspondence information, the self-position acquisition unit 18 may, for example, specify the forces for each finer position by interpolating the forces for each position included in the correspondence information, and also use it to acquire the self-position of the moving body 1.

[0031] Further, the self-position acquisition unit 18 may acquire the self-position by using, for example, a time-series filter. For example, when acquiring the self-position of the moving body 1 in a predetermined coordinate system where the forces applied to the hand units 11 existing at two or more different positions fit, the self-position acquisition unit 18 may use a time-series filter. The time-series filter may be, for example, a particle filter, a Kalman filter, etc., or other filters using the Monte Carlo method. In this case, by using a time-series filter such as a particle filter, the self-position where the forces applied to the hand units 11 existing at two or more different positions fit can be acquired. An example regarding the acquisition of the self-position using a time-series filter will be described later.

[0032] The movement control unit 19 controls the movement mechanism 14 using the self-position acquired by the self-position acquisition unit 18. This control using the self-position may be, for example, movement control for alignment with the reference magnet 20 or an object (such as a shelf 21 etc.) to which the reference magnet 20 is attached. For example, by repeating the acquisition of the self-position by the self-position acquisition unit 18 and the movement control by the movement control unit 19, highly accurate positioning of the moving body 1 can be performed with respect to the reference magnet 20 and an object having a predetermined relative positional relationship with the reference magnet 20.

[0033] Note that the self-position acquired by the self-position acquisition unit 18 is used for local movement control around the reference magnet 20 and cannot be used for global movement control. This is because the range of the magnetic force of the reference magnet 20 is limited. Therefore, the moving body 1 may separately include a current position acquisition unit for acquiring the current position of the moving body 1 used in global movement control. The current position acquisition unit may acquire the current position using, for example, methods such as SLAM (Simultaneous Localization and Mapping) using distance measurement results, Visual-SLAM, GPS (Global Positioning System), odometry, etc. This current position may indicate, for example, the position of the moving body 1 in the world coordinate system.

[0034] Next, a method for acquiring the self-position using a particle filter will be described. Here, for the sake of convenience of explanation, it is assumed that the relative relationship between the world coordinate system and the local coordinate system of the reference magnet 20 is known, and the position in the world coordinate system and the force applied to the hand unit 11 existing at that position are associated with each other by corresponding information.

[0035] First, the movement control unit 19 controls the movement mechanism 14 using the current position acquired by the current position acquisition unit, and moves the moving body 1 near the reference magnet 20. Then, the self-position acquisition unit 18 sets the current position of the moving body 1 as the initial value of the self-position candidate. Also, the robot control unit 16 moves the hand unit 11 to the first position in the robot coordinate system. It is assumed that at the first position, the hand unit 11 is in a predetermined posture. Then, the self-position acquisition unit 18 uses the force sensor 13 to acquire the force applied to the hand unit 11.

[0036] Next, the self-position acquisition unit 18 scatters a predetermined number of particles randomly displaced from the initial value of the self-position candidate. This predetermined number is not particularly limited, and may be, for example, 100. Then, the self-position acquisition unit 18 uses two or more pieces of correspondence information stored in the storage unit 17 to estimate the force applied to the hand unit 11 when the hand unit 11 exists at the first position in the robot coordinate system for the position of the moving body 1 corresponding to each particle. At this time, the self-position acquisition unit 18 may use the value of the correspondence information as it is, or may use the value of the correspondence information after interpolation. Then, the self-position acquisition unit 18 retains a predetermined number of particles with a smaller difference between the force acquired for the hand unit 11 at the first position and the estimated force, and discards the other particles. This predetermined number is not particularly limited, and may be, for example, 50. For example, outliers may be excluded by performing clustering on the particles.

[0037] The self-position acquisition unit 18 sets the position corresponding to the particle with the smallest difference between the acquired force and the estimated force as the new self-position candidate. The new self-position candidate may be calculated, for example, using a predetermined number of particles selected in ascending order of the difference between the acquired force and the estimated force. In this case, the new self-position candidate may be calculated by the weighted average of the reciprocals of the differences.

[0038] Next, the robot control unit 16 moves the hand unit 11 to a second position different from the first position in the robot coordinate system. It is assumed that at the second position, the hand unit 11 is in a predetermined posture. Then, the self-position acquisition unit 18 uses the force sensor 13 to acquire the force applied to the hand unit 11. Also, the self-position acquisition unit 18 scatters a predetermined number of particles randomly displaced from the new self-position candidates. This predetermined number is not particularly limited, and for example, it may be 50 or the like. Then, the self-position acquisition unit 18 uses two or more pieces of correspondence information stored in the storage unit 17 to estimate the force applied to the hand unit 11 when the hand unit 11 exists at the second position in the robot coordinate system for the position of the moving body 1 corresponding to each particle. Further, the self-position acquisition unit 18 retains a predetermined number of particles for which the difference between the force acquired for the hand unit 11 at the second position and the estimated force is smaller, and discards the other particles. This predetermined number is not particularly limited, and for example, it may be 50 or the like.

[0039] The self-position acquisition unit 18 sets the position corresponding to the particle with the smallest difference between the acquired force and the estimated force as the new self-position candidate. Also in this case, for example, a new self-position candidate may be calculated by weighted averaging using a plurality of particles. When only the forces applied to the hand unit 11 at the two positions, that is, the first and second positions, are acquired, the self-position acquisition unit 18 may set this new self-position candidate as the final self-position of the moving body 1. On the other hand, when the forces applied to the hand unit 11 at three or more positions are acquired, the self-position acquisition unit 18 continues to acquire a new self-position candidate using the force acquired for the hand unit 11 at the third position in the robot coordinate system and may set the self-position candidate at the time when those processes are completed as the self-position of the moving body 1.

[0040] In the above description, the case where only the robot 12 is operated to move the hand part 11 to a plurality of positions while the moving body 1 is stopped has been described, but this is not necessary. Even when the robot 12 is not operating, that is, in a state where the position of the hand part 11 in the local coordinate system of the moving body 1 does not change, the position of the hand part 11 may be changed by moving the carriage 15. Also in this case, the self-position estimation of the moving body 1 using the particle filter can be performed in the same manner.

[0041] Also, here, the case where the self-position estimation of the moving body 1 is performed using the particle filter has been described, but it goes without saying that the self-position estimation of the moving body 1 may be performed using other time-series filters such as the Kalman filter in the same manner.

[0042] Also, the first position, the second position, etc. may be determined in advance, or may not be. In the latter case, for example, the next position may be determined according to the force applied to the hand part 11 existing at a certain position. As an example, a direction orthogonal to the vector of the force applied to the hand part 11 existing at the first position may be specified, and a position separated from the first position by a predetermined distance in the specified direction may be set as the second position.

[0043] Next, the operation of the moving body 1 will be described using the flowchart of FIG. 4. (Step S101) The self-position acquisition unit 18 determines whether to acquire its own position. If it is determined to acquire its own position, the process proceeds to step S102. Otherwise, the process of step S101 is repeated until it is determined to acquire its own position. Note that the self-position acquisition unit 18 may determine, for example, to acquire its own position periodically.

[0044] (Step S102) The self-position acquisition unit 18 acquires the force applied to the hand part 11 using the force sensor 13. Note that before the force applied to the hand part 11 is acquired, the hand part 11 may be moved by, for example, the robot 12 or the carriage 15.

[0045] (Step S103) The self-position acquisition unit 18 determines whether it can acquire the self-position of the mobile body 1. If it can acquire the self-position, it proceeds to step S104; otherwise, it proceeds to step S105. Note that the self-position acquisition unit 18 may determine that it can acquire the self-position when the number of times of acquiring the force applied to the hand unit 11 reaches a predetermined number of times or more, and determine that it cannot acquire the self-position otherwise. The predetermined number of times may be, for example, 2 times, 3 times, or the like.

[0046] (Step S104) The self-position acquisition unit 18 acquires the self-position of the mobile body 1 by using the forces applied to the hand unit 11 existing at two or more different positions. Then, it returns to step S101.

[0047] (Step S105) The self-position acquisition unit 18 gives an instruction to the robot control unit 16 or the movement control unit 19 to move the hand unit 11. In response, the hand unit 11 is moved by the robot control unit 16 controlling the robot 12 or the movement control unit 19 controlling the movement mechanism 14. Then, it returns to step S102.

[0048] Note that the flowchart of FIG. 4 only includes processes related to the acquisition of the self-position. Separately from that, movement control such as alignment of the mobile body 1 using the acquired self-position may be performed by the movement control unit 19. Also, after the completion of the alignment, operations such as conveyance or assembly using the robot 12 may be performed by the robot control unit 16. Also, the order of the processes in the flowchart of FIG. 4 is an example, and the order of each step may be changed as long as the same result can be obtained. Also, in the flowchart of FIG. 4, the process ends due to power-off or an interrupt of the process end.

[0049] Next, the operation of the mobile body 1 according to the present embodiment will be described using a specific example. In this specific example, it is assumed that the reference magnet 20 is a permanent magnet and the magnet of the hand unit 11 is an electromagnet. Further, in this specific example, a case will be described in which the mobile body 1 moves close to the shelf 21, aligns with the shelf 21 using the reference magnet 20, and picks up and conveys the object to be conveyed placed on the shelf 21.

[0050] First, the mobile body 1 is moved to a known position near the reference magnet 20. This movement may be made according to an instruction by an operator. Then, with the electromagnet of the hand unit 11 turned on, the force applied to the hand unit 11 in a predetermined posture is measured using the force sensor 13, and the measurement result is associated with the position of the hand unit 11 and stored in the storage unit 17. The information thus stored is one piece of correspondence information. Note that the accumulation of the correspondence information is repeated while changing the position of the hand unit 11. In this way, a plurality of pieces of correspondence information are stored in the storage unit 17. In this specific example, it is assumed that the positions included in the correspondence information are positions in the world coordinate system.

[0051] Thereafter, it is assumed that the autonomous movement of the mobile body 1 is started. First, the mobile body 1 moves to the vicinity of the shelf 21, that is, to a position where the magnetic force of the reference magnet 20 acts, using the current position acquired by a current position acquisition unit (not shown), and stops. Then, when it is determined that the self-position is to be acquired (step S101), the self-position acquisition unit 18 turns on the electromagnet of the hand unit 11, moves the hand unit 11 to the first position in the robot coordinate system, and instructs the robot control unit 16 so that the posture of the hand unit 11 becomes a predetermined posture. In response to this instruction, the robot control unit 16 turns on the electromagnet of the hand unit 11, controls the robot 12, moves the hand unit 11 to the first position, and sets the posture of the hand unit 11 to a predetermined posture. Then, the self-position acquisition unit 18 acquires the force applied to the hand unit 11, which is the measurement value of the force sensor 13, and stores it in a recording medium (not shown) (step S102).

[0052] In this specific example, it is assumed that when the forces applied to the hand units 11 existing at two different positions are acquired, the acquisition of the self-position is to be performed. Then, at this point, since only the acquisition of the first force has been performed yet, the self-position acquisition unit 18 determines that it cannot acquire the self-position (step S103), moves the hand unit 11 to a second position different from the first position in the robot coordinate system, and instructs the robot control unit 16 so that the posture of the hand unit 11 becomes a predetermined posture. In response to this instruction, the robot control unit 16 controls the robot 12 to move the hand unit 11 to the second position and set the posture of the hand unit 11 to a predetermined posture (step S105). Then, the self-position acquisition unit 18 acquires the force applied to the hand unit 11, which is the measurement value of the force sensor 13, and stores it in a recording medium (not shown) (step S102).

[0053] Thereafter, since the forces applied to the hand units 11 existing at the first and second positions are acquired, the self-position acquisition unit 18 determines that it can acquire the self-position (step S103), and acquires the self-position of the moving body 1 using the forces applied to the hand units 11 existing at the first and second positions and the plurality of corresponding information stored in the storage unit 17 (step S104). In the acquisition of this self-position, for example, the above-described processing using the particle filter may be performed.

[0054] The movement control unit 19 may perform alignment with respect to the shelf 21 using the self-position thus acquired. For example, the movement control unit 19 may control the movement mechanism 14 so that the moving body 1 moves to a predetermined position using the acquired self-position. In addition, in accordance with the movement of the moving body 1, the acquisition of the self-position by the self-position acquisition unit 18 may be repeatedly performed. In this way, the moving body 1 can perform alignment with respect to the shelf 21, and at that position, using the robot 12, it can pick up the object to be conveyed placed on the shelf 21 and convey it to the destination. Also, at the destination, for example, alignment using a reference magnet may be performed.

[0055] As described above, according to the mobile body 1 of the present embodiment, the force applied to the hand unit 11 can be acquired using the force sensor 13, and the self-position of the mobile body 1 can be acquired using the acquired force. Therefore, the self-position can be acquired without using a laser sensor or an image sensor, so the self-position can be acquired without being affected by lighting or the like, and there is an advantage that the self-position can be acquired even in a place with many reflectors. In addition, since the self-position can be acquired without preparing a special pedestal or providing positioning holes on the floor surface, the self-position can be acquired with a simpler configuration. In addition, in a mobile collaborative robot, there is a high possibility of having a force sensor for acquiring the force applied to the hand unit. Therefore, by effectively utilizing such a force sensor, self-position identification can also be performed.

[0056] Further, in the above embodiment, each process or each function may be realized by being centrally processed by a single device or a single system, or may be realized by being distributedly processed by a plurality of devices or a plurality of systems.

[0057] In the above-described embodiment, each component may be configured by dedicated hardware, or components that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. At the time of its execution, the program execution unit may execute the program while accessing a storage unit or a recording medium. Further, the program may be executed by being downloaded from a server or the like, or may be executed by reading a program recorded on a predetermined recording medium (for example, an optical disk, a magnetic disk, a semiconductor memory, etc.). Further, this program may be used as a program constituting a program product. Also, the computer that executes the program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

[0058] Also, the above embodiments are examples for specifically implementing the present invention and do not limit the technical scope of the present invention. The technical scope of the present invention is indicated by the claims, not by the description of the embodiments, and is intended to include changes within the literal scope of the claims and the scope of equivalent meaning.

Explanation of Reference Numerals

[0059] 1 Mobile body, 11 Hand part, 12 Robot, 13 Force sensor, 14 Moving mechanism, 15 Mobile cart, 16 Robot control unit, 17 Storage unit, 18 Self-position acquisition unit, 19 Movement control unit, 20 Reference magnet

Claims

1. A mobile body, comprising: a hand portion having a magnet; a robot for moving the hand portion; a force sensor for acquiring the force applied to the hand portion; a moving mechanism for moving the mobile body, and a mobile cart to which the proximal end side of the robot is fixed; a robot control unit that moves the hand portion by controlling the robot; a storage unit that stores two or more pieces of correspondence information associating the relative position of the hand portion with respect to a reference magnet, which is a magnet arranged at a predetermined position in the moving environment of the mobile body, and the force applied to the hand portion existing at the relative position; a self-position acquisition unit that acquires the self-position of the mobile body using the forces applied to the hand portion existing at two or more different positions, which are acquired using the force sensor, and the two or more pieces of correspondence information; a movement control unit that controls the movement mechanism using the self-position acquired by the self-position acquisition unit.

2. The mobile body according to claim 1, wherein the force applied to the hand portion is a measured value of the force sensor.

3. The mobile body according to claim 1, wherein the force applied to the hand portion is the force applied to the hand portion by the reference magnet.

4. The mobile body according to claim 1, wherein the two or more different positions are two or more different positions of the hand portion moved by the robot when the mobile cart is stopped.

5. The mobile body according to claim 1, wherein the two or more different positions are two or more different positions of the hand portion moved by the mobile cart.

6. The mobile body according to any one of claims 1 to 5, wherein the self-position acquisition unit acquires the self-position using a time-series filter.

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