Autonomous mobile device, control method and program for autonomous mobile device

Abstract

To reduce various risks occurring when an autonomous mobile device travels on an inclined surface.SOLUTION: An autonomous mobile device 100 comprises a driving unit 140 which causes a vehicle body to travel, an attitude detection unit 130 which detects any one of a pitch angle, a roll angle, and a pitch rate of the vehicle body, and a control unit 110 which discriminates a travel surface on the basis of a detection value detected by the attitude detection unit 130 when the vehicle body driven by the driving unit 140 was traveling, and controls the driving unit 140 on the basis of the discriminated travel surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an autonomous mobile device, a control method for an autonomous mobile device, and a program. [Background technology]

[0002] Autonomous mobile devices have been used for a variety of purposes, and technological developments to improve the control of autonomous mobile devices are also underway. For example, Patent Document 1 discloses a motor-driven traveling device that can suppress unexpected vehicle body movements and safely release the brakes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-205002 Summary of the Invention [Problem to be solved by the invention]

[0004] The motor-driven traveling device disclosed in Patent Document 1 strengthens the braking force of the short brake (a brake that utilizes the effect of braking the motor shaft when the motor's power terminals are short-circuited) when the device is stopped on a slope when the user releases the brake to push the device by hand, compared to when the device is stopped on a level surface. This prevents the vehicle from sliding down the slope due to its own weight, thereby preventing unexpected vehicle movement and allowing the brake to be released safely. However, this control is only for when the vehicle is stopped on a slope, and does not prevent unexpected vehicle movement while traveling on a slope.

[0005] The present invention has been made in consideration of the above-mentioned situation, and aims to provide an autonomous mobile device, etc. that can reduce various risks that arise while the autonomous mobile device is traveling on a slope. [Means for solving the problem]

[0006] In order to achieve the above object, an autonomous mobile device according to the present invention comprises: a drive unit that drives the vehicle body; an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body; a control unit that determines a travel surface based on a detection value detected by the attitude detection unit while the drive unit is traveling, and controls the drive unit based on the determined travel surface; Equipped with.

[0007] a tracking distance detection unit that detects a tracking distance, which is a distance to a target to be tracked; The control unit controlling the drive unit to follow the target; When the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance, the driving unit is stopped; adjusting the following stopping distance based on the determined traveling surface; This may be done. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce various risks that may occur while an autonomous mobile device is traveling on a slope. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing the functional configuration of an autonomous mobile device according to a first embodiment. [Figure 2] 1 is a diagram showing the external appearance of an autonomous mobile device according to a first embodiment, viewed obliquely from above in front thereof; [Figure 3] 1 is a diagram showing the external appearance of an autonomous mobile device according to a first embodiment, as viewed from the side. [Figure 4] FIG. 2 is a diagram illustrating a case where the autonomous mobile device according to the first embodiment travels down a slope. [Figure 5] FIG. 2 is a diagram illustrating a case where the autonomous mobile device according to the first embodiment travels on an uphill slope. [Figure 6]FIG. 2 is a diagram illustrating a case where the autonomous mobile device according to the first embodiment travels on a horizontal slope. [Figure 7] 4 is a flowchart of a speed control process of the autonomous mobile device according to the first embodiment. [Figure 8] 4 is a diagram showing the relationship between the speed and the following distance when the autonomous mobile device according to the first embodiment travels. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an autonomous mobile device according to an embodiment of the present invention will be described with reference to the drawings. Note that the same or corresponding parts in the drawings are designated by the same reference numerals.

[0011] (Embodiment 1) The autonomous mobile device according to the first embodiment is a device that automatically moves by following a target such as a person, etc. An example of the functional configuration of the autonomous mobile device 100 according to the first embodiment is shown in Fig. 1, and examples of the external appearance are shown in Figs.

[0012] As shown in FIG. 1, the autonomous mobile device 100 includes a control unit 110, a memory unit 120, an attitude detection unit 130, a drive unit 140, an output unit 150, an operation acquisition unit 160, and a following distance detection unit 170.

[0013] The control unit 110 is composed of a CPU (Central Processing Unit) and the like, and executes various processes such as speed control process described below using programs stored in the storage unit 120. The control unit 110 supports a multi-thread function that executes multiple processes in parallel, and can execute various processes in parallel for the autonomous mobile device 100 to move autonomously.

[0014] The storage unit 120 is composed of a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and part or all of the ROM is composed of an electrically rewritable memory (such as a flash memory). The ROM stores programs to be executed by the CPU of the control unit 110 and data required in advance for executing the programs. The RAM stores data that is created or changed during program execution.

[0015] For example, variable data such as the maximum speed MS and following stopping distance SD when the autonomous mobile device 100 travels is stored in the storage unit 120. The maximum speed MS is set to the maximum value of the speed at which the autonomous mobile device 100 travels. Furthermore, the autonomous mobile device 100 travels while following a target to be followed (such as a user), and the control unit 110 controls the drive unit 140 so that the autonomous mobile device 100 stops when the distance (following distance) between the autonomous mobile device 100 and the target to be followed becomes equal to or less than the following stopping distance SD. This control allows the autonomous mobile device 100 to travel while following the target to be followed without colliding with it. Furthermore, even if the target to be followed travels at a speed faster than the maximum speed MS, the autonomous mobile device 100 only increases its speed up to the maximum speed MS, thereby preventing accidents caused by excessive speed.

[0016] The attitude detection unit 130 includes a gyro sensor and an acceleration sensor, and detects the attitude and changes in attitude of the body of the autonomous mobile device 100. More specifically, the attitude detection unit 130 detects the pitch angle, roll angle, pitch rate, etc. of the body of the autonomous mobile device 100.

[0017] The pitch angle is a rotation angle around the left-right axis of the autonomous mobile device 100, and indicates the degree of inclination of the slope when the road surface (traveling surface) on which the autonomous mobile device 100 is currently traveling is vertically inclined (uphill and downhill). The reference value of the pitch angle can be determined arbitrarily, but in this embodiment, the horizontal is set to 0 degrees, and the pitch angle takes a positive value on an uphill slope and a negative value on a downhill slope. In this embodiment, as shown in FIG. 2 , the forward direction of the autonomous mobile device 100 refers to the traveling direction when traveling following the user, the backward direction refers to the opposite side of the forward direction, the right direction refers to the right side of the traveling direction of the autonomous mobile device 100, and the left direction refers to the left side of the traveling direction of the autonomous mobile device 100.

[0018] The roll angle is the angle of rotation around the axis in the forward / backward direction of the autonomous mobile device 100, and indicates the degree of tilt when the surface on which the autonomous mobile device 100 is currently traveling is tilted to the left or right. Any method for determining the reference value of the roll angle can be used, but in this embodiment, horizontal is set to 0 degrees, and a positive value is taken when the left side is tilted downward, and a negative value is taken when the right side is tilted downward. Note that when traveling diagonally on a slope (in a direction that is not directly above, below, or beside), both the pitch angle and roll angle will be non-zero.

[0019] The pitch rate is the rate of change of the pitch angle over time. For example, when the autonomous mobile device 100 climbs up a step or the like on the traveling surface, or falls off a step down, the absolute value of the pitch rate becomes large. In this embodiment, the pitch angle takes a positive value on an upslope and a negative value on a downslope, so when the autonomous mobile device 100 climbs up a step or the like, the pitch rate becomes a large positive value, and when the autonomous mobile device 100 falls off a step down, the absolute value of the negative value becomes a large value.

[0020] The drive unit 140 moves the autonomous mobile device 100 under instructions (control) from the control unit 110. As shown in Fig. 2, the drive unit 140 has two crawlers 141. The autonomous mobile device 100 can perform forward and backward parallel movement (translational movement) by driving the two crawlers 141 in the same direction, rotate on the spot (change of direction) by driving the two crawlers 141 in opposite directions, and perform turning movement (translational movement + rotation (change of direction) movement) by driving the two crawlers 141 at different speeds.

[0021] In this embodiment, the driving unit 140 includes the crawler 141, but may include wheels instead of the crawler 141. Furthermore, the driving unit 140 is not limited to the crawler 141 or wheels, and may include any means for moving the autonomous mobile device 100.

[0022] The output unit 150 includes a speaker and can sound an alarm or output a message notifying the state of the autonomous mobile device 100 .

[0023] 2 and 3, the operation acquisition unit 160 is installed in a position that is easy for a user standing in front of the autonomous mobile device 100 to operate, and is equipped with a start button and a stop button. The autonomous mobile device 100 starts following travel when the start button of the operation acquisition unit 160 is pressed, and stops when the stop button is pressed.

[0024] The autonomous mobile device 100 may be provided with buttons other than the start button and stop button, a joystick, a touch panel, etc. as the operation acquisition unit 160. For example, a joystick may be provided so that the direction of travel of the joystick can be instructed to the autonomous mobile device 100 by the tilt direction, and the amount of tilt (tilt angle) can be instructed to the autonomous mobile device 100 by the amount of tilt (tilt angle). Furthermore, the operation acquisition unit 160 may be provided with a communication function so that it can receive remote operation from a user. In other words, the autonomous mobile device 100 is not limited to a tracking-type autonomous mobile device.

[0025] The following distance detection unit 170 includes a scanner-type laser rangefinder or the like, and detects the distance (following distance) from a target (person, another autonomous mobile device 100, etc.) that the autonomous mobile device 100 is following to the autonomous mobile device 100. However, the following distance detection unit 170 not only detects the distance to the target, but also detects objects (persons, walls, obstacles, reflective materials, etc.) present in the surroundings (left, right, and front in this embodiment) and can detect the distance to the object.

[0026] More specifically, the following distance detection unit 170 is installed in a position that allows scanning in front of, and to the left and right of, the autonomous mobile device 100, as shown in Fig. 3, and includes a light-emitting unit and a light-receiving unit. The light-emitting unit and the light-receiving unit rotate while repeatedly emitting a laser within a predetermined angle range (for example, ±160 degrees, where 0 degrees is the direction directly ahead) to scan the surroundings (the light-emitting unit emits a laser, and the light-receiving unit captures the laser reflected by the object). This allows the following distance detection unit 170 to capture objects present in that direction as a collection of points (point cloud) for each scan angle, and measure the distance to the object.

[0027] Then, for example, when the start button is pressed, the control unit 110 performs initial detection based on information acquired from the following distance detection unit 170, and tracks the detected object (scanning every short time (for example, 50 milliseconds) and tracking a cluster of points with small coordinate changes), thereby enabling stable detection of the object to be followed (for example, a person or another autonomous mobile device 100). Therefore, the control unit 110 can control the drive unit 140 to follow the object to be followed based on the information from the following distance detection unit 170.

[0028] Next, we will explain what risks may occur depending on the type of slope (downward slope, upward slope, side slope).

[0029] First, the risks when the autonomous mobile device 100 is traveling down a slope will be described with reference to Fig. 4. On a downslope, the autonomous mobile device 100 is likely to increase its speed due to gravity and is difficult to stop, so even if there are no steps on the slope, there is a risk that the autonomous mobile device 100 will fall forward or come into contact with the person to be followed (user 200) walking ahead.

[0030] For example, as shown in Fig. 4, when the autonomous mobile device 100 is traveling downhill 310 following the user 200, there is a risk that the autonomous mobile device 100, which is at point A, will tilt forward and tip over at point B when traveling over a downward step 311. In particular, if the center of gravity of the autonomous mobile device 100 and the cargo is biased forward, the autonomous mobile device 100 is likely to tilt significantly and tip over forward. Furthermore, the faster the traveling speed of the autonomous mobile device 100, the greater the impact it will receive from the downward step 311, increasing the risk of tipping over.

[0031] When the autonomous mobile device 100 is traveling at point A, the autonomous mobile device 100 emits a warning sound in accordance with the determination condition in step S108 of the speed control process, which will be described later. The user 200 who hears the warning sound can be aware that if the walking speed is too fast, the distance between the autonomous mobile device 100 and the user 200 becomes too great, and the autonomous mobile device 100 may not be able to follow. This reduces the risk that the autonomous mobile device 100 will become uncontrollable.

[0032] On the other hand, if the autonomous mobile device 100 tips over, it will fall down the slope, and on a downhill slope there is a high risk of hitting a user 200 walking in front of it. Therefore, in order to reduce the overall risk, that is, the risk of the autonomous mobile device 100 tipping over and damaging the autonomous mobile device itself or any cargo carried thereon, or hitting a user 200, it is better to limit the maximum speed MS to be slower than when traveling on normal flat ground, and to set the following stopping distance SD to a value greater than the standard following stopping distance (for example, 30 cm to 50 cm), which is a normal value.

[0033] Next, the risks when the autonomous mobile device 100 is traveling on an upslope will be described with reference to Fig. 5. On an upslope, even if there are no steps on the slope, there is a risk that the autonomous mobile device 100 will tip over backward due to gravity. However, there is a low risk that the autonomous mobile device 100 will come into contact with the person to be followed (user 200) walking ahead.

[0034] For example, as shown in FIG. 5, when the autonomous mobile device 100 is traveling uphill 320 following the user 200, there is a risk that the autonomous mobile device 100, which is at point C, will tilt backward and tip over at point D when traveling over an upward step 321. In particular, if the center of gravity of the autonomous mobile device 100 and its cargo is biased rearward, the autonomous mobile device 100 is likely to tilt significantly and tip over backward. Therefore, in order to reduce the risk of tipping as much as possible, it is better to limit the maximum speed MS according to the angle of inclination. In particular, when climbing up the upward step 321, the angle of inclination (pitch angle) increases. Therefore, if a pitch rate in a direction that increases the upward inclination angle is detected, the maximum speed MS can be further limited to reduce the risk of tipping over when climbing up the upward step.

[0035] When the autonomous mobile device 100 is traveling at point C, the autonomous mobile device 100 emits a warning sound in accordance with the determination condition in step S108 of the speed control process, which will be described later. The user 200 who hears the warning sound can be aware that if the walking speed is too fast, the distance between the autonomous mobile device 100 and the user 200 becomes too great, and the autonomous mobile device 100 may not be able to follow. This reduces the risk that the autonomous mobile device 100 will become uncontrollable.

[0036] On the other hand, if the autonomous mobile device 100 tips over, it falls down the slope, so on an upslope there is a low risk of hitting a user 200 walking ahead. Therefore, the following stopping distance SD can remain normal (standard following stopping distance). Note that if the autonomous mobile device 100 tips over, even if it does not hit the user 200, there is a risk that the autonomous mobile device itself or its cargo may be damaged, or that it may hit surrounding objects or people, so it is useful to limit the maximum speed MS to reduce the risk of tipping over.

[0037] As described above, the case where the vehicle runs over an upward step 321 on an upward slope 320 (FIG. 5) has already been described. Including this pattern, there are the following four patterns for the combination of slope and step.

[0038] (1) Uphill slope + uphill step In this case, as described above, the tilt angle increases and the risk of tipping over increases, so the risk of the vehicle body rolling backward can be reduced by controlling the vehicle to particularly increase deceleration (limit the maximum speed MS).

[0039] (2) Uphill slope + downhill step In this case, the risk of tipping over does not increase compared to an uphill slope without a step because the inclination angle of the uphill slope is canceled out by the step. Therefore, when passing over a step on an uphill slope (when a pitch rate in the direction of a smaller uphill slope angle is detected), no special control is required.

[0040] (3) Downhill slope + uphill step In this case, the inclination angle of the downward slope is canceled out by the upward step, so the risk of tipping over does not increase compared to a downward slope without an upward step. Therefore, when passing over an upward step on a downward slope (when a pitch rate in the direction of a smaller downward slope angle is detected), no special control is required.

[0041] (4) Downhill slope + downhill step In this case, if the vehicle decelerates when a downward step is detected (a pitch rate in the direction of an increasing downward slope angle is detected), the risk of the vehicle rolling forward due to inertial forces increases. On the other hand, if the vehicle accelerates at a downward step, the risk of the vehicle rolling forward due to inertial forces decreases, but the risk after passing over the downward step increases (such as the risk of falling due to a strong impact from the downward step or the risk of contact with a user walking in front). In other words, the risk increases whether the vehicle decelerates or accelerates. Therefore, when passing over a downward step on a downward slope (when a pitch rate in the direction of an increasing downward slope angle is detected), there is no need for special control other than the control for downward slopes described above (reducing the maximum speed MS and increasing the following stopping distance SD).

[0042] Next, the risks that arise when the autonomous mobile device 100 is traveling sideways on a slope (traveling on a horizontal slope) will be described with reference to FIG.

[0043] When the autonomous mobile device 100 is traveling on a lateral slope 330, if there are unevenness caused by a downward step or an upward step, there is a risk that the autonomous mobile device 100 will roll over due to lateral sway. However, because the change in lateral inclination (roll angle) is limited by an angle determined by the height of the unevenness and the width of the autonomous mobile device, the risk of roll over is smaller than in the case of the downward slope and upward slope described above. Therefore, the maximum speed MS is limited to a smaller extent to suppress lateral sway.

[0044] Furthermore, if the autonomous mobile device 100 falls over, it will fall down the slope, so on a horizontal slope there is little risk of contact with a user walking ahead. Therefore, the following stopping distance SD can remain normal (standard following stopping distance).

[0045] Based on the above considerations, in this embodiment, the maximum speed MS and following stopping distance SD are adjusted for each slope as follows: The standard maximum speed is set to 4 to 8 km / h, which is about the speed at which a farm worker walks or jogs, for example. Downhill slope: The maximum speed MS is limited to the maximum speed for uphill and downhill slopes (for example, 50% to 60% of the standard maximum speed), and the following stopping distance SD is set to a larger value, the following stopping distance for downhill slopes (for example, 2 to 2.5 times the standard following stopping distance). Uphill: The following stopping distance (SD) remains the standard following stopping distance, but the maximum speed (MS) is limited to the maximum speed for uphill and downhill slopes (for example, 50% to 60% of the standard maximum speed). If the pitch rate increases, the maximum speed (MS) is further limited to the maximum speed for increasing slopes (for example, 30% to 40% of the standard maximum speed). Side slope: The following stopping distance SD remains the standard following stopping distance, but the maximum speed MS is weakly limited to a maximum speed for side slopes (for example, 70% to 80% of the standard maximum speed).

[0046] The speed control process for adjusting the maximum speed MS and following stopping distance SD in this manner will be described with reference to Fig. 7. Execution of this speed control process begins when the user starts up the autonomous mobile device 100. Note that the speed control process is not the only process that begins execution when the autonomous mobile device 100 starts up. For example, execution of various processes for the autonomous mobile device 100 to move autonomously may begin in parallel, such as a following travel process for traveling while following a target to be followed, or a manual travel process for traveling according to instructions from the user.

[0047] When the speed control process is started, first, the control unit 110 determines whether the start button has been pressed (step S101). If the start button has not been pressed (step S101; No), the process returns to step S101. If the start button has been pressed (step S101; Yes), the control unit 110 detects the attitude (pitch angle, roll angle, and pitch rate) of the body of the autonomous mobile device 100 using the attitude detection unit 130 (step S102).

[0048] Then, the control unit 110 determines whether the absolute value of the pitch angle detected in step S102 is less than a reference pitch angle (for example, 5 to 10 degrees) (step S103). If the absolute value of the pitch angle is equal to or greater than the reference pitch angle (step S103; No), the control unit 110 determines that the traveling surface on which the autonomous mobile device 100 is currently traveling is an uphill or downhill slope, and reduces the maximum speed MS of the autonomous mobile device 100 to set it to a maximum speed for uphill or downhill slopes (for example, 50% to 60% of the standard maximum speed) (step S104).

[0049] Then, the control unit 110 determines whether the traveling surface is a downward slope or not, that is, whether the pitch angle is a negative value or not (step S105). If the traveling surface is a downward slope (step S105; Yes), the control unit 110 increases the following stopping distance SD and sets it to a following stopping distance for a downward slope (for example, 2 to 2.5 times the standard following stopping distance) (step S106).

[0050] Then, the control unit 110 performs speed control based on the maximum speed MS and following stopping distance SD set in the previous processing (step S107). Specifically, the control unit 110 transmits information on the maximum speed MS and following stopping distance SD to other processing (following driving processing and manual driving processing) that is being executed in parallel with the speed control processing. As a result, the traveling speed is limited to a speed equal to or less than the maximum speed MS, and during following driving, driving control is performed such that the vehicle stops when it approaches the target to be followed.

[0051] Then, control unit 110 determines whether the following stop distance is greater than a distance threshold (e.g., 60 cm to 1 m) or whether the maximum speed is less than a speed threshold (e.g., 60% to 70% of the standard maximum speed) (step S108). If at least one of the conditions that the following stop distance is greater than the distance threshold and the maximum speed is less than the speed threshold is satisfied (step S108; Yes), control unit 110 causes output unit 150 to sound an alarm (step S109) and proceeds to step S110.

[0052] If both the conditions that the following stop distance is equal to or less than the distance threshold and the condition that the maximum speed is equal to or greater than the speed threshold are met (step S108; No), the control unit 110 determines whether the stop button has been pressed (step S110). If the stop button has not been pressed (step S110; No), the control unit 110 returns to step S102.

[0053] If the stop button is pressed (step S110; Yes), the control unit 110 controls the driving unit 140 to stop the traveling (step S111), and the process returns to step S101.

[0054] On the other hand, if the control unit 110 determines in step S105 that the traveling surface is not a downward slope (step S105; No), the control unit 110 determines whether the pitch rate is greater than the reference pitch rate, i.e., whether the slope is increasing (step S112). If the slope is increasing (step S112; Yes), the control unit 110 further reduces the maximum speed MS and sets it to a maximum speed for increasing slope (for example, 30 to 40% of the standard maximum speed) (step S113). Then, the control unit 110 sets the following stopping distance SD to the standard following stopping distance (step S114), and proceeds to step S107.

[0055] On the other hand, if the slope is not increasing (step S112; No), the control unit 110 proceeds to step S114, leaving the maximum speed MS set to the maximum speed for up and down slopes.

[0056] Furthermore, in step S103, if the control unit 110 determines that the absolute value of the pitch angle detected in step S102 is less than the reference pitch angle (step S103; Yes), the control unit 110 determines whether the absolute value of the roll angle detected in step S102 is less than the reference roll angle (for example, 10 degrees to 15 degrees) (step S115).

[0057] If the absolute value of the roll angle is less than the reference roll angle (step S115; Yes), the control unit 110 sets the maximum speed MS to the standard maximum speed (step S116) and proceeds to step S114. On the other hand, if the absolute value of the roll angle is equal to or greater than the reference roll angle (step S115; No), the control unit 110 reduces the maximum speed MS and sets it to a maximum speed for a lateral slope (for example, 70% to 80% of the standard maximum speed) (step S117), and proceeds to step S114.

[0058] Here, the control of the autonomous mobile device 100 according to the traveling surface will be explained using the above-mentioned flowchart. The traveling surface on which the autonomous mobile device 100 travels includes flat traveling surfaces and slopes. On a flat traveling surface, the absolute value of the pitch angle of the autonomous mobile device 100 is less than the reference value (step S103; Yes), and the roll angle is also less than the reference value (step S115; Yes). A slope can be either a vertical slope or a horizontal slope depending on the traveling direction. A vertical slope can be an upslope, where the altitude increases as the autonomous mobile device travels, or a downslope, where the altitude decreases as the autonomous mobile device travels. Furthermore, when traveling on a slope in a direction where the altitude does not change, the slope is called a horizontal slope.

[0059] The autonomous mobile device 100 may travel on a slope in the following cases: (1) traveling straight up the slope, (2) traveling diagonally up the slope, (3) traveling sideways on the slope (in a direction where the altitude does not change), (4) traveling straight down the slope, or (5) traveling diagonally down the slope. First, it is determined whether the pitch angle is less than a reference value (step S103), and the control unit is controlled based on the subsequent flowchart. For this reason, (2) is treated as (1), and (5) is treated as (4).

[0060] By the above speed control process, the relationship between the speed of the autonomous mobile device 100 and the following distance (the distance from the autonomous mobile device 100 to the target to be followed) becomes as shown in FIG.

[0061] For example, the relationship between the speed and the following distance when the autonomous mobile device 100 is traveling on a flat traveling surface is shown by solid line 401. On a flat traveling surface, the maximum speed MS is set to the standard maximum speed, and the following stopping distance SD is set to the standard following stopping distance. Therefore, when the following distance is greater than a certain size, the speed becomes the standard maximum speed, and as the following distance becomes smaller, the speed decreases, and when the following distance becomes the standard following stopping distance, the speed becomes zero.

[0062] The relationship between the speed and the following distance when the autonomous mobile device 100 is traveling on a horizontal slope is indicated by a dotted line 402. On a horizontal slope, the maximum speed MS is set to a maximum speed for a horizontal slope that is smaller than the standard maximum speed, and the following stopping distance SD is set to the standard following stopping distance. Therefore, when the following distance is greater than a certain value, the speed becomes the maximum speed for a horizontal slope (e.g., 70% to 80% of the standard maximum speed), and as the following distance decreases, the speed decreases, and when the following distance reaches the standard following stopping distance, the speed becomes zero. When traveling on a horizontal slope, there is a low risk of the autonomous mobile device 100 coming into contact with the user even if it loses its balance. When traveling on a horizontal slope, safety can be improved by slowing the speed of the autonomous mobile device 100 that follows the user compared to when traveling on a flat traveling surface. Because the distance between the user and the autonomous mobile device 100 is not too great, the user can use the autonomous mobile device 100 without sacrificing convenience, for example, when harvesting crops and placing them on the autonomous mobile device.

[0063] The relationship between the speed and the following distance when the autonomous mobile device 100 is traveling uphill is indicated by the dashed-dotted line 403. On an uphill slope, the maximum speed MS is set to a maximum speed for uphill and downhill slopes that is lower than the standard maximum speed and the maximum speed for sidehill slopes, and the following stopping distance SD is set to the standard following stopping distance. Therefore, when the following distance is greater than a certain value, the speed becomes the maximum speed for uphill and downhill slopes (e.g., 50% to 60% of the standard maximum speed), and as the following distance decreases, the speed decreases, and when the following distance reaches the standard following stopping distance, the speed becomes zero. When traveling uphill, if the autonomous mobile device 100 loses its balance, the autonomous mobile device 100 may roll backward. In this case, the autonomous mobile device 100 is unlikely to come into contact with the user it is following, but there is a risk of contact with nearby people or crops. When traveling uphill, safety can be improved by slowing the speed of the autonomous mobile device 100 following the user compared to when traveling on a flat traveling surface. Since the user is not too far away from the autonomous mobile device 100, the user can harvest crops and place them on the autonomous mobile device without losing convenience.

[0064] The relationship between the speed and the following distance when the slope increases while the autonomous mobile device 100 is traveling uphill is indicated by the two-dot chain line 404. In this case, the maximum speed MS is set to the maximum speed for increasing slope, which is even smaller than the maximum speed for uphill and downhill slopes, and the following stop distance SD is set to the standard following stop distance. Therefore, when the following distance is greater than a certain size, the speed becomes the maximum speed for increasing slope (e.g., 30% to 40% of the standard maximum speed), and as the following distance decreases, the speed decreases until the following distance reaches the standard following stop distance, at which point the speed becomes zero. An increase in slope while traveling uphill corresponds to a case in which the autonomous mobile device runs over an uphill step or the like while traveling uphill. In this case, if the autonomous mobile device 100 loses its balance, there is a possibility that the autonomous mobile device 100 will roll backward. In this case, the autonomous mobile device 100 is unlikely to come into contact with the user it is following, but there is a risk of contact with nearby people or crops. When traveling uphill, safety can be improved by slowing the speed of the autonomous mobile device 100 following the user compared to when traveling on a flat surface. Because the user is not too far away from the autonomous mobile device 100, the user can harvest crops and place them on the autonomous mobile device without sacrificing convenience.

[0065] The relationship between the speed and the following distance when the autonomous mobile device 100 is traveling on a downward slope is indicated by a solid line 405. On a downward slope, the maximum speed MS is set to the maximum speed for up and down slopes, which is smaller than the standard maximum speed and the maximum speed for side slopes, and the following stopping distance SD is set to the following stopping distance for down slopes, which is larger than the standard following stopping distance. Therefore, when the following distance is greater than a certain size, the speed becomes the maximum speed for up and down slopes (for example, 50% to 60% of the standard maximum speed), and as the following distance becomes smaller, the speed decreases, and when the following distance reaches the following stopping distance for down slopes (for example, 2 to 2.5 times the standard following stopping distance), the speed becomes 0.

[0066] The maximum speed of the autonomous mobile device 100 when traveling on a lateral slope is preferably lower than the speed when traveling on a flat traveling surface. The speed when traveling on an uphill or downhill slope is preferably lower than the speed when traveling on a flat traveling surface. This reduces the risk of contact with people if the autonomous mobile device 100 loses its balance and falls over.

[0067] It should be noted that there is no need to change the control when there is a downhill step while traveling uphill, or when there is an uphill step while traveling downhill. Even if there is a downhill step on an uphill slope, it is expected that the vehicle body will sway slightly when descending the step, but this does not increase the risk of contact with the person being followed. Similarly, even if there is an uphill step on a downhill slope, it is expected that the vehicle body will sway slightly when ascending the step, but this does not increase the risk of contact with the person being followed.

[0068] The speed control process of the autonomous mobile device 100 has been described above. However, the speed control process described above (shown in FIG. 7) is merely one example of a speed control process. That is, in the speed control process described above, the control unit 110 compares the pitch angle, roll angle, and pitch rate with their respective reference values ​​(reference pitch angle, reference roll angle, reference pitch rate), and sets the maximum speed MS and the following stopping distance SD based on the magnitude relationship between the values. However, the method for setting the maximum speed MS and the following stopping distance SD is not limited to this method. The content and order of the process may be changed as long as control is performed to adjust the maximum speed MS and the following stopping distance SD based on the posture of the body of the autonomous mobile device 100.

[0069] For example, the larger the pitch angle or roll angle, the smaller the maximum speed MS may be. Furthermore, on a downhill slope, the larger the pitch angle, the larger the following stopping distance SD may be. By setting the maximum speed MS and following stopping distance SD in this way, the risk of tipping over or contact with the autonomous mobile device 100 can be more flexibly controlled.

[0070] (Embodiment 2) The autonomous mobile device 100 according to the first embodiment described above travels by following the target to be followed. However, the autonomous mobile device does not necessarily have to perform follow-up traveling. An autonomous mobile device 101 according to a second embodiment, which does not perform follow-up traveling, will be described.

[0071] The autonomous mobile device 101 has the same functional configuration as the autonomous mobile device 100, but since the autonomous mobile device 101 does not perform following travel, it does not need to include the following distance detection unit 170. The autonomous mobile device 101 basically travels according to user instructions via the operation acquisition unit 160. The operation acquisition unit 160 is not limited to a joystick, which is a user interface that allows the user to directly input instructions, but may also be a remotely or proximally operable device that receives instructions wirelessly or otherwise from a user located at a long or short distance. The autonomous mobile device 101 may also be configured to automatically travel along a route stored in advance.

[0072] Furthermore, since the autonomous mobile device 101 does not travel in a following manner, the storage unit 120 of the autonomous mobile device 101 stores the maximum speed MS, but does not need to store the following stopping distance SD.

[0073] The speed control process according to the second embodiment is the same as the speed control process according to the first embodiment (FIG. 7), except that the processes related to setting the following stop distance and determining the following distance are omitted. In the autonomous mobile device 101 according to the second embodiment, the following travel process is not executed, so in step S107 of the speed control process (FIG. 7), the control unit 110 transmits information on the maximum speed MS and the following stop distance SD to the manual travel process, for example. This limits the travel speed to a speed equal to or less than the maximum speed MS.

[0074] Even when not performing follow-up driving, the risk of the autonomous mobile device 101 tipping over depending on the slope is the same as for the autonomous mobile device 100, so the speed control processing of embodiment 2 limits the maximum speed MS, allowing the autonomous mobile device 101 to travel more safely on slopes.

[0075] (Effects, etc.) As described above, the control unit 110 of the autonomous mobile devices 100, 101 determines the traveling surface based on the detection value detected by the attitude detection unit 130 while traveling, and controls the driving unit 140 based on the determined traveling surface, thereby reducing various risks (risk of falling, risk of contact, etc.) that may occur while traveling on an inclined surface without impairing usability as much as possible. Furthermore, the control unit 110 controls the driving unit 140 by adjusting the following stopping distance and maximum speed, which improves the degree of freedom in controlling the driving unit 140 during autonomous traveling compared to directly stopping the driving unit 140 or directly changing the speed of the driving unit 140.

[0076] Note that the functions of the autonomous mobile devices 100, 101 can also be implemented by a computer such as a regular PC (Personal Computer). Specifically, in the above embodiment, the speed control processing program performed by the autonomous mobile devices 100, 101 has been described as being pre-stored in the ROM of the storage unit 120. However, the program may be stored and distributed on a computer-readable recording medium such as a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a DVD (Digital Versatile Disc), a MO (Magneto-Optical Disc), a memory card, or a USB (Universal Serial Bus) memory, and the program may be read and installed on a computer to configure a computer that can realize the above-described functions. Furthermore, the program may be distributed via a communication network such as the Internet, and the program may be read and installed on a computer to configure a computer that can realize the above-described functions.

[0077] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and the present invention includes the inventions described in the claims and their equivalents. The inventions described in the original claims of this application are appended below.

[0078] (Appendix 1) a drive unit that drives the vehicle body; an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body; a control unit that determines a travel surface based on a detection value detected by the attitude detection unit while the drive unit is traveling, and controls the drive unit based on the determined travel surface; An autonomous mobile device comprising:

[0079] (Appendix 2) a tracking distance detection unit that detects a tracking distance, which is a distance to a target to be tracked; The control unit controlling the drive unit to follow the target; When the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance, the driving unit is stopped; adjusting the following stopping distance based on the determined traveling surface; 2. The autonomous mobile device of claim 1.

[0080] (Appendix 3) The control unit determining whether the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is a downward slope, the following stopping distance is increased compared to when the traveling surface is not a downward slope. 3. The autonomous mobile device according to claim 2.

[0081] (Appendix 4) the control unit determines a traveling surface based on the detection value of the attitude detection unit, and adjusts the maximum speed of the drive unit based on the determined traveling surface. 4. The autonomous mobile device according to claim 1.

[0082] (Appendix 5) The control unit determining whether the traveling surface is a slope or a flat surface based on the pitch angle and roll angle detected by the attitude detection unit; When the traveling surface is a slope, the maximum speed of the drive unit is reduced compared to when the traveling surface is a flat traveling surface. 5. The autonomous mobile device according to claim 4.

[0083] (Appendix 6) The control unit determining whether the traveling surface is a horizontal slope or a vertical slope based on the pitch angle and roll angle detected by the attitude detection unit; When the travel surface is a vertical slope, the maximum speed of the drive unit is reduced compared to when the travel surface is a horizontal slope. 6. The autonomous mobile device according to claim 5.

[0084] (Appendix 7) The control unit determining whether the traveling surface is an uphill slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is an upslope, it is determined whether or not the inclination angle of the traveling surface is increasing based on the pitch rate detected by the attitude detection unit, and when the inclination angle is increasing, the maximum speed of the drive unit is reduced compared to when the traveling surface is an upslope and the inclination angle is not increasing. 5. The autonomous mobile device according to claim 4.

[0085] (Appendix 8) a computer of an autonomous mobile device including a drive unit that drives a vehicle body and an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body, determining a traveling surface based on a detection value detected by the attitude detection unit while the driving unit is traveling; controlling the drive unit based on the determined traveling surface; A method for controlling an autonomous mobile device.

[0086] (Appendix 9) A computer of an autonomous mobile device including a drive unit that drives a vehicle body and an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body, A process of determining a traveling surface based on a detection value detected by the attitude detection unit while the driving unit is traveling; and a process of controlling the drive unit based on the determined traveling surface; A program to execute. [Explanation of symbols]

[0087] 100, 101... autonomous mobile device, 110... control unit, 120... memory unit, 130... attitude detection unit, 140... drive unit, 141... crawler, 150... output unit, 160... operation acquisition unit, 170... following distance detection unit, 200... user, 310... downward slope, 311... downward step, 320... upward slope, 321... upward step, 330... side slope, 401, 405... solid line, 402... dotted line, 403... dashed line, 404... dashed line

Claims

1. A drive unit that drives a vehicle body; an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body; a control unit that determines a travel surface based on a detection value detected by the attitude detection unit while the drive unit is traveling, and controls the drive unit based on the determined travel surface; a tracking distance detection unit that detects a tracking distance, which is the distance to a target to be tracked; Equipped with The control unit controlling the drive unit to follow the target; When the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance, the driving unit is stopped; adjusting the following stopping distance based on the determined traveling surface; determining whether the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is a downward slope, the following stopping distance is increased compared to when the traveling surface is not a downward slope, determining a travel surface based on the detection value of the attitude detection unit, and adjusting the maximum speed of the drive unit based on the determined travel surface; determining whether the traveling surface is a slope or a flat surface based on the pitch angle and roll angle detected by the attitude detection unit; When the traveling surface is a slope, the maximum speed of the drive unit is reduced compared to when the traveling surface is a flat traveling surface; determining whether the traveling surface is a horizontal slope or a vertical slope based on the pitch angle and roll angle detected by the attitude detection unit; When the travel surface is a vertical slope, the maximum speed of the drive unit is reduced compared to when the travel surface is a horizontal slope. Autonomous mobile device.

2. A drive unit that drives the vehicle body; an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body; a control unit that determines a travel surface based on a detection value detected by the attitude detection unit while the drive unit is traveling, and controls the drive unit based on the determined travel surface; a tracking distance detection unit that detects a tracking distance, which is the distance to a target to be tracked; Equipped with The control unit controlling the drive unit to follow the target; When the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance, the driving unit is stopped; adjusting the following stopping distance based on the determined traveling surface; determining whether the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is a downward slope, the following stopping distance is increased compared to when the traveling surface is not a downward slope, determining a travel surface based on the detection value of the attitude detection unit, and adjusting the maximum speed of the drive unit based on the determined travel surface; determining whether the traveling surface is an uphill slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is an upslope, it is determined whether or not the inclination angle of the traveling surface is increasing based on the pitch rate detected by the attitude detection unit, and when the inclination angle is increasing, the maximum speed of the drive unit is reduced compared to when the traveling surface is an upslope and the inclination angle is not increasing. Autonomous mobile device.

3. a computer of an autonomous mobile device including a drive unit for driving a vehicle body, an attitude detection unit for detecting at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body, and a following distance detection unit for detecting a following distance, which is a distance to a target to be followed, determining a traveling surface based on a detection value detected by the attitude detection unit while the driving unit is traveling; controlling the drive unit based on the determined traveling surface; controlling the drive unit to follow the target; When the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance, the driving unit is stopped; adjusting the following stopping distance based on the determined traveling surface; determining whether the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is a downward slope, the following stopping distance is increased compared to when the traveling surface is not a downward slope, determining a travel surface based on the detection value of the attitude detection unit, and adjusting the maximum speed of the drive unit based on the determined travel surface; determining whether the traveling surface is a slope or a flat surface based on the pitch angle and roll angle detected by the attitude detection unit; When the traveling surface is a slope, the maximum speed of the drive unit is reduced compared to when the traveling surface is a flat traveling surface; determining whether the traveling surface is a horizontal slope or a vertical slope based on the pitch angle and roll angle detected by the attitude detection unit; When the travel surface is a vertical slope, the maximum speed of the drive unit is reduced compared to when the travel surface is a horizontal slope. A method for controlling an autonomous mobile device.

4. a computer of an autonomous mobile device including a drive unit for driving a vehicle body, an attitude detection unit for detecting at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body, and a following distance detection unit for detecting a following distance, which is a distance to a target to be followed, determining a traveling surface based on a detection value detected by the attitude detection unit while the driving unit is traveling; controlling the drive unit based on the determined traveling surface; controlling the drive unit to follow the target; When the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance, the driving unit is stopped; adjusting the following stopping distance based on the determined traveling surface; determining whether the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is a downward slope, the following stopping distance is increased compared to when the traveling surface is not a downward slope, determining a travel surface based on the detection value of the attitude detection unit, and adjusting the maximum speed of the drive unit based on the determined travel surface; determining whether the traveling surface is an uphill slope based on the pitch angle detected by the attitude detection unit; When the traveling surface is an upslope, it is determined whether or not the inclination angle of the traveling surface is increasing based on the pitch rate detected by the attitude detection unit, and when the inclination angle is increasing, the maximum speed of the drive unit is reduced compared to when the traveling surface is an upslope and the inclination angle is not increasing. A method for controlling an autonomous mobile device.

5. a driving unit that drives a vehicle body; an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body; and a following distance detection unit that detects a following distance, which is a distance to a target to be followed; a process of determining a traveling surface based on a detection value detected by the attitude detection unit while the driving unit is traveling; a process of controlling the drive unit based on the determined traveling surface; a process of controlling the drive unit so as to follow the target; a process of stopping the drive unit when the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance; a process of adjusting the following stopping distance based on the determined traveling surface; a process of determining whether or not the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; a process of increasing the following stopping distance when the traveling surface is a downward slope compared to when the traveling surface is not a downward slope; a process of determining a travel surface based on a detection value of the attitude detection unit, and adjusting a maximum speed of the drive unit based on the determined travel surface; a process of determining whether the traveling surface is a slope or a flat traveling surface based on the pitch angle and roll angle detected by the attitude detection unit; a process of reducing the maximum speed of the drive unit when the traveling surface is a slope compared to when the traveling surface is a flat traveling surface; A process of determining whether the traveling surface corresponds to a horizontal slope or a vertical slope based on the pitch angle and roll angle detected by the attitude detection unit; and a process of reducing the maximum speed of the drive unit when the traveling surface is a vertical slope compared to when the traveling surface is a horizontal slope; A program to execute.

6. a driving unit that drives a vehicle body; an attitude detection unit that detects at least one of a pitch angle, a roll angle, and a pitch rate of the vehicle body; and a following distance detection unit that detects a following distance, which is a distance to a target to be followed; a process of determining a traveling surface based on a detection value detected by the attitude detection unit while the driving unit is traveling; a process of controlling the drive unit based on the determined traveling surface; a process of controlling the drive unit so as to follow the target; a process of stopping the drive unit when the following distance detected by the following distance detection unit becomes equal to or less than a following stop distance; a process of adjusting the following stopping distance based on the determined traveling surface; a process of determining whether or not the traveling surface is a downward slope based on the pitch angle detected by the attitude detection unit; a process of increasing the following stopping distance when the traveling surface is a downward slope compared to when the traveling surface is not a downward slope; a process of determining a travel surface based on a detection value of the attitude detection unit, and adjusting a maximum speed of the drive unit based on the determined travel surface; a process of determining whether the traveling surface is an uphill slope based on the pitch angle detected by the attitude detection unit; and when the traveling surface is an upslope, determining whether or not the inclination angle of the traveling surface is increasing based on the pitch rate detected by the attitude detection unit, and when the inclination angle is increasing, reducing the maximum speed of the drive unit compared to when the traveling surface is an upslope and the inclination angle is not increasing; A program to execute.

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