Sensing unit and autonomous mobile robot

Abstract

To provide a sensing unit and autonomous mobile robot that can generate a stable trajectory even when the target being followed turns a corner. [Solution] This sensing unit includes an imaging unit 26 that images a marker SP attached to a moving tracking target, and a calculation unit that calculates a circular arc trajectory O1 connecting the imaging unit 26 and the marker SP in a plan view based on the image data captured by the imaging unit 26.

Description

Technical Field

[0001] The present invention relates to a sensing unit and an autonomous mobile robot.

Background Art

[0002] In Patent Document 1 below, there is described an autonomous mobile robot that moves along a movement path while sequentially reading a plurality of signs arranged along the movement path with a camera, and performs predetermined operations in the order of preset operation numbers based on the identification numbers read from the signs. This autonomous mobile robot stores an operation table (operation list) in which the autonomous mobile robot performs predetermined operations in the order of preset operation numbers (see FIG. 6 of Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, for the joint work of a person and an autonomous mobile robot, it has been required to equip the autonomous mobile robot with a person-following function. Since the above-mentioned autonomous mobile robot can maintain a certain distance from a sign, by a person holding the sign in some form, it can follow while maintaining a certain distance from the person. However, when a person turns a corner of a passage, the following autonomous mobile robot takes a trajectory approaching the corner, and in some cases, the autonomous mobile robot may collide with the corner.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a sensing unit and an autonomous mobile robot that can generate a stable trajectory even when a following target turns a corner.

Means for Solving the Problems

[0006] To solve the above problems, the sensing unit of the present invention comprises an imaging unit that captures an image of a marker attached to a moving tracking target, and a calculation unit that calculates an arc trajectory connecting the imaging unit and the marker in a plan view based on the image data captured by the imaging unit.

[0007] Furthermore, the autonomous mobile robot of the present invention is equipped with the above-mentioned sensing unit. [Effects of the Invention]

[0008] According to the present invention, a stable trajectory can be generated even when the target being followed is turning a corner. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of an autonomous mobile robot and its movement path as viewed from above, according to one embodiment of the present invention. [Figure 2] This is a block diagram showing the configuration of an autonomous mobile robot in one embodiment of the present invention. [Figure 3] This is a front view showing an example of a sign detected by a sensing unit in one embodiment of the present invention. [Figure 4] This figure shows the operation table for an autonomous mobile robot in one embodiment of the present invention. [Figure 5] This is a schematic diagram illustrating the trajectory of an autonomous mobile robot in its first mode according to one embodiment of the present invention. [Figure 6] This is an explanatory diagram for calculating the circular arc trajectory of an autonomous mobile robot in one embodiment of the present invention. [Figure 7] This is an explanatory diagram for calculating the circular arc trajectory of an autonomous mobile robot in one embodiment of the present invention. [Figure 8] This is a flowchart of the first mode in one embodiment of the present invention. [Figure 9] This is an explanatory diagram of the speed control in the first mode in one embodiment of the present invention. [Modes for carrying out the invention]

[0010] One embodiment of the present invention will be described below with reference to the drawings. The present invention can be applied to automated guided vehicles in factories and logistics warehouses, service robots in public facilities such as facilities, halls, and airports, and work robots in indoor and outdoor environments where GPS (Global Positioning System) is difficult to use.

[0011] Figure 1 is a schematic diagram of an autonomous mobile robot 1 and its movement path 10 in one embodiment of the present invention, viewed from above. As shown in Figure 1, the autonomous mobile robot 1 is capable of switching between two modes of operation: a first mode M1 in which it follows a target 100, and a second mode M2 ​​in which it moves according to a pre-set operation schedule while detecting markers SP placed along the movement path 10.

[0012] The target to follow 100 is, for example, a worker (person) working in a factory. The autonomous mobile robot 1 moves from home position A to work position B while following the target to follow 100 in first mode M1. Between home position A and work position B, a corner section 11 is formed where the movement path 10 bends at a 90-degree angle.

[0013] Near the work position B, an item placement unit 13 on which an item 12 is placed is positioned. The item placement unit 13 is, for example, a table, shelf, or rack. The autonomous mobile robot 1 is equipped with a tray 2 to support the item 12. When the follow target 100 (person) places the item 12 on the tray 2, the autonomous mobile robot 1 detects the item 12 by its weight or other means, switches to the second mode M2, and automatically transports the item 12 from the work position B to the original home position A.

[0014] In the second mode M2, the autonomous mobile robot 1 moves while detecting a sign SP arranged along the movement path 10 with an imaging unit 26 (see FIG. 2) mounted on the robot body 20. That is, the autonomous mobile robot 1 is guided by the sign SP and moves along the movement path 10. As the sign SP arranged along the movement path 10, a signpost can be exemplified.

[0015] Here, the "signpost" refers to a structure having a sign SP (marker) and placed at a predetermined location on or near the movement path 10. The sign SP includes identification information (pattern ID) of the structure. As shown in FIG. 3 described later, the sign SP of the present embodiment is formed by arranging a first cell C1 capable of reflecting light and a second cell C2 incapable of reflecting light on a two-dimensional plane.

[0016] FIG. 2 is a block diagram showing the configuration of the autonomous mobile robot 1 in an embodiment of the present invention. As shown in FIG. 2, the autonomous mobile robot 1 includes a sensing unit 21, a driving unit 22, a control unit 23, a communication unit 24, and a storage unit 25.

[0017] The sensing unit 21 includes an imaging unit 26 and a calculation unit 27. The driving unit 22 includes a motor control unit 28, two motors 29, left and right driving wheels 20L and 20R, and a sensor unit 40. The configurations of the sensing unit 21 and the driving unit 22 are merely examples, and other configurations may be used.

[0018] The imaging unit 26 is arranged on the front surface in the traveling direction of the autonomous mobile robot 1. The imaging unit 26 of the present embodiment includes a light that irradiates infrared LED light forward and a camera that images reflected light (infrared LED light) reflected by the sign SP. The infrared LED light is suitable for dark places such as factories or places with strong visible light. The camera is preferably a camera combined with an infrared filter, for example. The imaging unit 26 may be configured to irradiate detection light other than infrared LED light.

[0019] The calculation unit 27 performs a binarization process based on the captured image transmitted from the imaging unit 26 to form binarized image data consisting of black and white. Furthermore, it uses this image data to detect the marker SP and calculates the distance L and direction (angle θ) at which the marker SP is located relative to the autonomous mobile robot 1. The angle θ is the direction (angle) of the marker SP with respect to the direction of travel of the autonomous mobile robot 1. In the example in Figure 1, the marker SP is positioned in front of the autonomous mobile robot 1, so the angle θ is not shown (angle θ = 0°).

[0020] The calculation unit 27 calculates the distance L and angle θ to the marker SP based on the size of the marker SP on the image data captured by the imaging unit 26 and the preset actual size of the marker SP. In other words, the calculation unit 27 in this embodiment can calculate the distance L and angle θ to the marker SP using only one camera (imaging unit 26).

[0021] Figure 3 is a front view showing an example of a marker SP detected by the sensing unit 21 in one embodiment of the present invention. As shown in Figure 3, the label SP is formed by arranging a first cell C1 capable of reflecting infrared LED light and a second cell C2 that cannot reflect infrared LED light on a two-dimensional plane.

[0022] The first cell C1 is formed from a material with high reflectivity to infrared LED light, such as aluminum foil or a thin film of titanium oxide. The second cell C2 is formed from a material with low reflectivity to infrared LED light, such as an infrared cut film, a polarizing film, an infrared absorbent, or black felt.

[0023] The first cell C1 and the second cell C2 are both squares of the same size, and the entire mark SP formed by them is also a square. The mark SP has an identification area 30 and a frame area 31 surrounding the identification area 30. In this embodiment, the identification area 30 consists of a matrix pattern of 4 rows x 4 columns.

[0024] In the example shown in Figure 3, if the first cell C1 (white) is represented as "1" and the second cell C2 (black) as "0 (zero)" using binary code, the identification area 30 contains 16 bits of information, allowing the calculation unit 27 to read the identification information (pattern ID) of the marker SP.

[0025] Furthermore, the identification area 30 is not limited to a 4x4 pattern; it may also be a 3x3 or smaller pattern, or a 5x5 or larger pattern.

[0026] The frame region 31 is a non-reflective frame region and is formed solely by the second cell C2 (black). The frame region 31 is formed in the shape of a square frame surrounding the identification region 30 with the second cell C2. The calculation unit 27, for example, detects the four corners 32 of the frame region 31 and calculates the size of the marker SP from the length S of any one side between the corners 32.

[0027] The calculation unit 27 reads the actual size of the marker SP from the storage unit 25 or the like based on the identification information obtained from the identification area 30, and calculates the distance L between the robot body 20 and the marker SP based on the size of the marker SP on the image data captured by the imaging unit 26 and the stored actual size of the marker SP corresponding to the identification information of the marker SP.

[0028] Furthermore, the calculation unit 27 calculates the center coordinates of the marker within the field of view from the four corners 32 of the frame area 31. From these center coordinates, the calculation unit 27 calculates the direction (angle θ) of the marker SP relative to the direction of travel of the autonomous mobile robot 1.

[0029] The autonomous mobile robot 1 moves guided by the signpost SP, and when the distance L to the signpost SP becomes closer than a predetermined threshold, it performs the following action.

[0030] Returning to Figure 2, the drive wheel 20L is located on the left side relative to the direction of travel of the autonomous mobile robot 1. The drive wheel 20R is located on the right side relative to the direction of travel of the autonomous mobile robot 1. Note that the autonomous mobile robot 1 may have wheels other than the drive wheels 20L and 20R in order to stabilize its posture. The motor 29 rotates the left and right drive wheels 20L and 20R in accordance with the control of the motor control unit 28.

[0031] The motor control unit 28 supplies power to the left and right motors 29 based on the angular velocity command value input from the control unit 23. The autonomous mobile robot 1 moves forward or backward as the left and right motors 29 rotate at an angular velocity corresponding to the power supplied by the motor control unit 28. In addition, the direction of travel of the autonomous mobile robot 1 is changed by creating a difference in the angular velocity of the left and right motors 29.

[0032] The sensor unit 40 detects movement information of the autonomous mobile robot 1. The sensor unit 40 is, for example, an encoder provided on the left and right motors 29, which detects the speed and rotation angle of the left and right motors 29. By detecting the speed and rotation angle of the left and right motors 29, the distance traveled, direction, speed, etc., of the autonomous mobile robot 1 can be detected. Note that the sensor unit 40 is not limited to encoders, but may also be a gyroscope, an accelerometer, or a combination of multiple types of sensors.

[0033] The communication unit 24 communicates with external devices. The communication unit 24 is capable of communicating with, for example, a higher-level device (not shown). The memory unit 25 stores the operation schedule of the autonomous mobile robot 1 (see Figure 4), the individual identification information of the marker SP, and the actual size of the marker SP corresponding to that identification information. The control unit 23 is connected to the sensing unit 21, the drive unit 22, the communication unit 24, and the storage unit 25, and controls the overall movement of the autonomous mobile robot 1.

[0034] Figure 4 shows the operation table of the autonomous mobile robot 1 in one embodiment of the present invention. As shown in Figure 4, the operation table of the autonomous mobile robot 1 stores a STEP input sequence in which the autonomous mobile robot 1 performs predetermined actions in the order of pre-set operation numbers. The operator can edit the operation table using the GUI software shown in Figure 5 (for example, by selecting each parameter from a pull-down menu). The operation table is stored in both the autonomous mobile robot 1 and the host device.

[0035] The sequence of numbers on the left edge of the page shown in Figure 5 is the operation number. Each operation number is associated with the following items: "Action," "Parameter," and "Option." "Action" registers the operation of the autonomous mobile robot 1. "Parameter" registers various parameters of the operation of the autonomous mobile robot 1. "Option" registers information associated with the operation of the autonomous mobile robot 1, for example, operation commands when the autonomous mobile robot 1 operates in conjunction with a linkage device (such as an automatic door).

[0036] The autonomous mobile robot 1 performs its actions in the order of the action numbers in the action table. Specifically, when the autonomous mobile robot 1 moves from work position B to home position A in second mode M2, the autonomous mobile robot 1 first performs the "signpost" action shown in Figure 4 and detects the signpost SP from work position B shown in Figure 1. The "Parameters" set for the "signpost" are, from left to right, "signpost size", "signpost No.", "following direction", "signpost left-right distance", and "signpost front-back distance".

[0037] Specifically, the autonomous mobile robot 1 detects a marker SP having registered identification information ("signpost No." is "1") from the image data captured by the imaging unit 26. If the marker SP is detected, the autonomous mobile robot 1 calculates the distance L to the marker SP based on the registered size of the marker SP ("signpost size" is "S") and the size of the marker SP in the image data.

[0038] Next, the autonomous mobile robot 1 moves towards the signpost SP while calculating the distance L. The parameters for this movement are "following direction" as "forward", "left-right distance from signpost" as "0", and "front-back distance from signpost" as "0.5". Specifically, the autonomous mobile robot 1 moves forward towards the "front" of signpost SP, with a left-right distance of "0" meters and a front-back distance of "0.5" meters. When the autonomous mobile robot 1 approaches to within "0.5" meters of signpost SP, the "signpost" operation ends, and the next operation is performed.

[0039] The next action is "rotation". The "Parameters" set for "rotation" are, from left to right, "direction of rotation" and "angle of rotation". Here, the "direction of rotation" is "left" and the "angle of rotation" is "90" degrees. In other words, autonomous mobile robot 1 rotates 90 degrees to the left in front of marker SP. Once autonomous mobile robot 1 has rotated 90 degrees to the left, the "rotation" action is finished and the next action is executed.

[0040] The next action is "Forward". The "Parameter" set for "Forward" is "Distance Traveled". Here, the "Distance Traveled" is "3" meters. In other words, autonomous mobile robot 1 will move 3 meters forward from in front of signpost SP towards home position A. When autonomous mobile robot 1 has moved 3 meters forward, the "Forward" action is complete. In this way, the autonomous mobile robot 1 can move from work position B to home position A by executing the operations in the order of the operation numbers in the operation table shown in Figure 12.

[0041] Next, we will describe the operation of the autonomous mobile robot 1 in its first mode M1 (following mode).

[0042] Figure 5 is a schematic diagram illustrating the trajectory of the autonomous mobile robot 1 in its first mode M1 according to one embodiment of the present invention. As shown in Figure 5, the autonomous mobile robot 1 moves in pursuit of the target 100.

[0043] The target 100 (person) is wearing, for example, work clothes or a vest with a marker SP attached. The marker SP is the first marker SP1 used in the first mode M1, and has different identification information from the second marker SP2 used in the second mode M2. The autonomous mobile robot 1 detects the first marker SP1 and moves while maintaining a distance L to avoid collision with the target 100.

[0044] Here, when the target 100 turns a corner 11 of the movement path 10, if the autonomous mobile robot 1 behind it simply maintains a distance L and moves in the direction (angle θ) where it detected the marker SP, it will take a trajectory O2 that approaches the corner 11, potentially resulting in a collision with the corner 11. For this reason, the autonomous mobile robot 1 (calculation unit 27) is configured to generate an arc trajectory O1 connecting the robot body 20 (imaging unit 26) in a plan view and the marker SP.

[0045] Figures 6 and 7 are explanatory diagrams for calculating the circular arc trajectory O1 of the autonomous mobile robot 1 in one embodiment of the present invention. The Z-axis direction shown in Figure 6 represents the direction of travel (forward / backward) of the autonomous mobile robot 1. The Z-axis direction is also the direction in which the vertical line of the center of the field of view of the imaging unit 26 extends. The X-axis direction shown in Figure 6 represents the left-right direction of the autonomous mobile robot 1. The symbol c in Figure 6 represents the rotation center of the calculated circular arc trajectory O1.

[0046] As described above, the calculation unit 27 detects the marker SP based on the image data from the imaging unit 26 and calculates the distance and direction (angle θ) at which the marker SP is located relative to the autonomous mobile robot 1 (imaging unit 26). Then, when L is the distance between the imaging unit 26 and the marker SP, v is the speed at which the robot follows the marker SP (see Figure 7), and θ is the angle of the marker SP with respect to the vertical line (Z axis) of the center of the imaging unit 26's field of view, the calculation unit 27 calculates the angular velocity ω (see Figure 7), which forms the circular arc trajectory O1, based on the following equation (1).

[0047]

number

[0048] As a result, as shown in Figure 7, the autonomous mobile robot 1 does not immediately turn even if the target 100 turns, but follows it in a trajectory that turns gradually. This allows the autonomous mobile robot 1 to avoid colliding with corners 11 in the travel path 10, as shown in Figures 1 and 5.

[0049] Figure 8 is a flowchart of the first mode M1 in one embodiment of the present invention. Figure 9 is an explanatory diagram of the speed control of the first mode M1 in one embodiment of the present invention. The process shown in Figure 8 should be performed for each frame (one image) of the captured image captured by the imaging unit 26.

[0050] As shown in Figure 8, in the first mode M1, it is first determined whether or not the tracking target 100 (first marker SP1) has been detected (step S1). If step S1 is YES, the target position (x,z) of the tracking target 100 is obtained from the image data of the imaging unit 26 (step S2). Then, the calculation unit 27 calculates the distance L and angle θ from the tracking target 100 based on the target position (step S4).

[0051] If step S1 is NO, for example, the tracking target 100 may have turned a corner 11 and temporarily disappeared from view. In such a case, the difference in distance from the target position of the tracking target 100 detected in the previous frame is calculated, and the target position is estimated (step S3). As a result, the calculation unit 27 can calculate (estimate) the distance L and angle θ from the tracking target 100 from the target position (step S4). The distance of the autonomous mobile robot 1 can be detected by the sensor unit 40 (see Figure 2).

[0052] Next, it is determined whether the calculated distance L is greater than or equal to a certain value (L1) (step S5). L1 is the preferred tracking distance of the autonomous mobile robot 1 to the tracking target 100, and is set, for example, within the range of 1 to 3 meters. If step S5 is YES, as shown in Figure 9(a), the calculation unit 27 sets the speed v at which the autonomous mobile robot 1 moves forward to a speed limit v. max This is set (step S6). Also, if step S5 is NO, as shown in Figure 9(b), the calculation unit 27 sets the forward speed v of the autonomous mobile robot 1 to a speed proportional to L / L1 (step S7).

[0053] The calculation unit 27 calculates ω based on the above-described equation (1) (step S8). Next, it determines whether the calculated distance L is greater than or equal to a certain value (L2) (step S9). L2 is a threshold smaller than L1 and is set to prevent the autonomous mobile robot 1 from getting too close to the target 100. If step S9 is NO, as shown in Figure 9(c), the calculation unit 27 sets the forward speed v of the autonomous mobile robot 1 to 0 (zero) (step S10). It also sets the angular velocity ω of the autonomous mobile robot 1 to 0 (zero).

[0054] If step S9 is YES, or if step S10 is followed, the calculation unit 27 transmits the velocity v and angular velocity ω to the control unit 23 (see Figure 2) (step S11). Upon receiving the velocity v and angular velocity ω, the control unit 23 transmits these parameters to the motor control unit 28, which drives the motor 29. As a result, if step S9 is YES, the autonomous mobile robot 1 moves along the circular trajectory O1.

[0055] Next, the autonomous mobile robot 1 determines whether or not it has received a tracking completion signal (step S12). The tracking completion signal may be output by the tracking target 100 (person) by operating an operation panel (not shown) of the autonomous mobile robot 1 or by operating a handheld terminal device, or by various sensors installed near the work position B detecting the arrival of the autonomous mobile robot 1.

[0056] If step S12 is NO, the process returns to step S1 and the above-described process is repeated. On the other hand, if step S12 is YES, the first mode M1 ends. In this way, the autonomous mobile robot 1 can move from the home position A to the work position B shown in Figure 1, following the target 100, without colliding with the corner section 11, by continuously calculating the angular velocity ω that generates the circular trajectory O1.

[0057] As described above, the sensing unit 21 of this embodiment includes an imaging unit 26 that images a marker SP attached to a moving tracking target 100, and a calculation unit 27 that calculates an arc trajectory O1 connecting the imaging unit 26 and the marker SP in a plan view based on the image data captured by the imaging unit 26. With this configuration, a stable trajectory can be generated even when the tracking target 100 turns a corner 11.

[0058] Furthermore, in this embodiment, as shown in Figures 6 and 7, when L is the distance between the imaging unit 26 and the marker SP, v is the speed at which the robot follows the marker SP, and θ is the angle of the marker SP with respect to the vertical line of the center of the field of view of the imaging unit 26, the calculation unit 27 calculates the angular velocity ω that forms the circular arc trajectory O1 based on the above-described equation (1). With this configuration, the autonomous mobile robot 1 moves along a sufficiently circular arc trajectory O1, so that collisions can be avoided even if there is a corner section 11 that bends at a 90-degree angle, for example.

[0059] Furthermore, in this embodiment, as shown in Figure 9, the calculation unit 27 reduces the speed v for following the target SP as the distance L between the imaging unit 26 and the target SP decreases. With this configuration, the autonomous mobile robot 1 can adjust its speed so as not to collide with the target 100, thereby enhancing safety.

[0060] The autonomous mobile robot 1 of this embodiment is equipped with the sensing unit 21 described above. With this configuration, a stable trajectory can be generated even when the target to be followed 100 turns a corner 11.

[0061] Furthermore, the autonomous mobile robot 1 of this embodiment can switch between two modes of operation: a first mode M1 in which it follows a target 100 marked with a first marker SP1 along an arc trajectory O1 calculated by the sensing unit 21, and a second mode M2 ​​in which it moves according to a preset operation table while detecting a second marker SP2 arranged along the movement path 10 by the sensing unit 21. With this configuration, by switching between the first mode M1 and the second mode M2, collaborative work between a human and the autonomous mobile robot 1 can be smoothly performed.

[0062] Furthermore, in this embodiment, the autonomous mobile robot 1 follows the target 100 in the first mode M1 to the work position B (predetermined position), and then switches to the second mode M2 ​​to return to the home position A (original position). With this configuration, after the autonomous mobile robot 1 finishes its work, the target 100 (person) does not have to take the autonomous mobile robot 1 back to the home position A, as the autonomous mobile robot 1 automatically returns to the home position A, thus improving work efficiency.

[0063] Preferred embodiments of the present invention have been described above with reference to the drawings, but the present invention is not limited to the above embodiments. The shapes and combinations of the components shown in the above embodiments are examples, and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention.

[0064] For example, in the above embodiment, a person was used as an example of the follow target 100, but the follow target 100 is not limited to a person; for example, it could be another autonomous mobile robot 1. For example, if there are multiple autonomous mobile robots 1 that follow a person in a line, a display unit can be provided at the rear of each autonomous mobile robot 1 to display the first sign SP1, or the first sign SP1 can be attached to the rear of each autonomous mobile robot 1 so that the rear autonomous mobile robot 1 follows the front autonomous mobile robot 1. [Explanation of Symbols]

[0065] 1…Autonomous mobile robot, 2…Tray, 10…Movement path, 11…Corner section, 12…Item, 13…Item placement section, 20…Robot body, 20L…Drive wheel, 20R…Drive wheel, 21…Sensing unit, 22…Drive unit, 23…Control unit, 24…Communication unit, 25…Storage unit, 26…Imaging unit, 27…Calculation unit, 28…Motor control unit, 29…Motor, 30…Identification area, 31…Frame area, 32…Corner section, 40…Sensor unit, 100…Track target, A…Home position, B…Work position, C1…First cell, C2…Second cell, L…Distance, M1…First mode, M2…Second mode, O1…Circular arc trajectory, O2…Trajectory, SP…Marker, SP1…First marker, SP2…Second marker

Claims

1. An imaging unit that captures images of markers attached to a moving tracking target, The system includes a calculation unit that calculates a circular arc trajectory connecting the imaging unit and the marker in a plan view, based on the image data captured by the imaging unit. Sensing unit.

2. When L is the distance between the imaging unit and the marker, v is the speed at which the unit tracks the marker, and θ is the angle of the marker with respect to the vertical line at the center of the imaging unit's field of view, The calculation unit calculates the angular velocity ω forming the circular arc trajectory based on the following formula: [Math 1] The sensing unit according to claim 1.

3. The calculation unit reduces the speed v of tracking the marker as the distance L between the imaging unit and the marker decreases. The sensing unit according to claim 2.

4. A sensing unit comprising the sensing unit described in any one of claims 1 to 3, Autonomous mobile robot.

5. A first mode in which the tracking target marked with a first marker follows along the arc trajectory calculated by the sensing unit, The sensing unit can switch between a second mode, in which the unit moves according to a preset operation schedule while detecting a second sign placed along the movement path, and a second mode, in which the unit moves according to a preset operation schedule. The autonomous mobile robot according to claim 4.

6. After moving to a predetermined position by following the tracking target in the first mode, the operation switches to the second mode and returns to the original position. The autonomous mobile robot according to claim 5.

Images