JP7798267B2 - Autonomous mobile device, control method and program for autonomous mobile device - Google Patents

Description

The present invention relates to an autonomous mobile device, a control method for an autonomous mobile device, and a program.

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 movement and safely release the brakes.

Japanese Patent Application Laid-Open No. 2017-205002

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 vehicle by hand, compared to when the device is stopped on a level surface. This prevents the vehicle from sliding downhill 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.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide an autonomous mobile device that can reduce various risks that arise while the autonomous mobile device is traveling on an inclined surface.

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.

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.

This invention can reduce various risks that arise while an autonomous mobile device is traveling on a slope.

1 is a block diagram showing the functional configuration of an autonomous mobile device according to a first embodiment. 1 is a diagram showing the external appearance of an autonomous mobile device according to a first embodiment, as viewed obliquely from above in front thereof; 1 is a diagram showing the external appearance of an autonomous mobile device according to a first embodiment, as viewed from the side; 4A and 4B are diagrams illustrating a case where the autonomous mobile device according to the first embodiment travels on a downward slope. 4A and 4B are diagrams illustrating a case where the autonomous mobile device according to the first embodiment travels on an uphill slope. 1A and 1B are diagrams illustrating a case where the autonomous mobile device according to the first embodiment travels on a horizontal slope. 4 is a flowchart of a speed control process of the autonomous mobile device according to the first embodiment. 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.

An autonomous mobile device according to an embodiment of the present invention will now be described with reference to diagrams. Note that identical or corresponding parts in the diagrams will be designated by the same reference numerals.

(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.

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.

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

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

For example, variable data such as the maximum speed MS and following stopping distance SD when the autonomous mobile device 100 travels are stored in the storage unit 120. The maximum speed MS is set to the maximum speed at which the autonomous mobile device 100 travels. Furthermore, the autonomous mobile device 100 travels following a target to be followed (such as a user), and the control unit 110 controls the drive unit 140 to stop 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 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, preventing accidents caused by excessive speed.

The attitude detection unit 130 is equipped with 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.

The pitch angle is the 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 (driving surface) on which the autonomous mobile device 100 is currently traveling is vertically inclined (uphill and downhill). The reference value for the pitch angle can be determined arbitrarily, but in this embodiment, horizontal is set to 0 degrees, and the value is positive on uphill slopes and negative on downhill slopes. Note that in this embodiment, as shown in Figure 2, the forward direction of the autonomous mobile device 100 refers to the direction of travel 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 autonomous mobile device 100's direction of travel, and the left direction refers to the left side of the autonomous mobile device 100's direction of travel.

The roll angle is the rotation angle around the axis of the autonomous mobile device 100 in the forward/backward direction, and indicates the degree of tilt when the surface on which the device is currently traveling is tilted to the left or right. The reference value for the roll angle can be determined arbitrarily, but in this embodiment, horizontal is set to 0 degrees, and a downward tilt to the left side is a positive value, and a downward tilt to the right side is a negative value. Note that when traveling diagonally on a slope (in a direction that is neither directly above, below, nor beside), both the pitch angle and roll angle will be non-zero.

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

The drive unit 140 drives the autonomous mobile device 100 under instructions (control) from the control unit 110. As shown in Figure 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.

In this embodiment, the drive unit 140 is equipped with crawlers 141, but wheels may be provided instead of the crawlers 141. Furthermore, the drive unit 140 is not limited to crawlers 141 or wheels, and may be equipped with any means for moving the autonomous mobile device 100.

The output unit 150 is equipped with a speaker and can sound an alarm or output a message notifying the user of the status of the autonomous mobile device 100.

As shown in Figures 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 on the operation acquisition unit 160 is pressed, and stops when the stop button is pressed.

The autonomous mobile device 100 may be equipped with buttons other than the start and stop buttons, 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, and the amount of inclination (tilt angle) can be instructed to the autonomous mobile device 100, and the travel speed can be instructed. The operation acquisition unit 160 may also be equipped with communications functionality so that it can receive remote operation from the user. In other words, the autonomous mobile device 100 is not limited to a tracking-type autonomous mobile device.

The following distance detection unit 170 is equipped with a scanner-type laser rangefinder or the like, and detects the distance (following distance) from the autonomous mobile device 100 to the target being followed (a person, another autonomous mobile device 100, etc.). However, the following distance detection unit 170 not only detects the distance to the target being followed, but can also detect objects (people, walls, obstacles, reflective materials, etc.) present in the surrounding area (to the left, right, and front in this embodiment) and detect the distance to the object.

More specifically, the following distance detection unit 170 is installed in a position that allows it to scan the front, left, and right of the autonomous mobile device 100, as shown in Figure 3, and is equipped with a light-emitting unit and a light-receiving unit. The light-emitting unit and light-receiving unit then rotate while repeatedly emitting a laser within a predetermined angle range (for example, ±160 degrees, with 0 degrees being 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.

The control unit 110 then performs initial detection based on information obtained from the following distance detection unit 170, for example, when the start button is pressed, and tracks the detected object (scanning every short time (e.g., 50 milliseconds) and tracking clusters of point clouds with small coordinate changes), thereby enabling stable detection of the object to be followed (e.g., 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 information from the following distance detection unit 170.

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

First, the risks involved when the autonomous mobile device 100 is traveling downhill will be explained with reference to Figure 4. On a downhill slope, gravity makes it easy for the autonomous mobile device 100 to increase its speed and make it difficult to stop, so even if there are no steps on the slope, there is a risk of the autonomous mobile device 100 falling forward or coming into contact with the person to be followed (user 200) walking in front of it.

For example, as shown in Figure 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 the downward step 311. In particular, if the center of gravity of the autonomous mobile device 100 and its cargo is biased forward, it is likely to tilt significantly and tip forward. Furthermore, the faster the autonomous mobile device 100 travels, the greater the impact it will receive from the downward step 311, increasing the risk of tipping over.

When the autonomous mobile device 100 is traveling at point A, the autonomous mobile device 100 emits a warning sound in accordance with the judgment conditions of step S108 of the speed control process, which will be described later. A user 200 who hears the warning sound can be aware that if their walking speed is too fast, they may become too far away from the autonomous mobile device 100, which could cause the autonomous mobile device 100 to be unable to follow them. This reduces the risk that the autonomous mobile device 100 will become uncontrollable.

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 it coming into contact with a user 200 walking in front of it. Therefore, to reduce the overall risk, i.e., the risk of the autonomous mobile device 100 tipping over and damaging the autonomous mobile device itself or its cargo, or coming into contact with 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 (e.g., 30 cm to 50 cm), which is a normal value.

Next, the risks when the autonomous mobile device 100 is traveling uphill will be explained with reference to Figure 5. On an uphill slope, 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 in front of it.

For example, as shown in Figure 5, when the autonomous mobile device 100 is traveling uphill slope 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, it is likely to tilt significantly and tip backward. Therefore, 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 over an 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 risk of tipping over when climbing over an upward step can be reduced by further limiting the maximum speed MS.

When the autonomous mobile device 100 is traveling at point C, the autonomous mobile device 100 emits a warning sound in accordance with the judgment conditions of step S108 of the speed control process described below. When the user 200 hears the warning sound, they can be aware that if they walk too fast, they may become too far away from the autonomous mobile device 100, which could cause the autonomous mobile device 100 to be unable to follow them. This reduces the risk of the autonomous mobile device 100 becoming uncontrollable.

On the other hand, if the autonomous mobile device 100 tips over, it will fall down the slope, so on an uphill slope there is a low risk of contact with a user 200 walking in front. 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 contact the user 200, there is a risk of damaging the autonomous mobile device itself or its cargo, or of contacting surrounding objects or people, so it is useful to limit the maximum speed MS to reduce the risk of tipping over.

As described above, when a vehicle runs over an upward step 321 on an upward slope 320 (Figure 5), there are four possible combinations of slopes and steps, including this pattern:

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

(2) Uphill slope + downhill step In this case, the slope angle of the uphill slope is canceled out by the downhill step, so the risk of tipping over does not increase compared to an uphill slope without a downhill step. Therefore, when passing over a downhill 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.

(3) Downward slope + upward step In this case, the slope 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.

(4) Downward Slope + Downward 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 body rolling forward due to inertial force increases. On the other hand, if the vehicle accelerates at the downward step, the risk of the vehicle body rolling forward due to inertial force decreases, but the risk after passing over the downward step (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) increases. 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), no special control is required other than the control for the downward slope described above (reducing the maximum speed MS and increasing the following stopping distance SD).

Next, we will explain the risks that occur when the autonomous mobile device 100 is traveling sideways on a slope (traveling on a horizontal slope) with reference to Figure 6.

When the autonomous mobile device 100 is traveling on a lateral slope 330, if there are unevenness caused by downward or upward steps, there is a risk that the autonomous mobile device 100 will roll over due to lateral sway. However, because changes in the lateral inclination (roll angle) are 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 and upward slopes described above. Therefore, the maximum speed MS is limited to a lower value to suppress lateral sway.

Furthermore, if the autonomous mobile device 100 tips 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).

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 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 slope: The following stopping distance SD remains the standard following stopping distance, and the maximum speed MS is limited to a maximum speed for uphill and downhill slopes (for example, 50% to 60% of the standard maximum speed), but if the pitch rate increases, the maximum speed MS is further limited to a 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, and the maximum speed MS is slightly limited to a maximum speed for side slopes (for example, 70% to 80% of the standard maximum speed).

The speed control process for adjusting the maximum speed MS and following stopping distance SD in this manner will be described with reference to Figure 7. This speed control process begins execution 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, various processes for the autonomous mobile device 100 to move autonomously may begin execution in parallel, such as a following driving process for driving while following a target to be followed, or a manual driving process for driving according to instructions from the user.

When the speed control process begins, the control unit 110 first 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 body attitude (pitch angle, roll angle, and pitch rate) of the autonomous mobile device 100 using the attitude detection unit 130 (step S102).

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 (e.g., 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 current traveling surface is an uphill slope, and reduces the maximum speed MS of the autonomous mobile device 100 to a maximum speed for uphill slopes (e.g., 50% to 60% of the standard maximum speed) (step S104).

Then, the control unit 110 determines whether the traveling surface is a downhill slope, i.e., whether the pitch angle is a negative value (step S105). If it is a downhill slope (step S105; Yes), the control unit 110 increases the following stopping distance SD and sets it to a downhill following stopping distance (for example, 2 to 2.5 times the standard following stopping distance) (step S106).

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 about 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 driving speed is limited to a speed below the maximum speed MS, and during following driving, driving control is performed so that the vehicle stops when approaching the target to be followed.

Then, the 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 met (step S108; Yes), the control unit 110 sounds an alarm from the output unit 150 (step S109) and proceeds to step S110.

If both the conditions that the following stop distance is less than the distance threshold and the maximum speed is greater than or equal to 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.

When the stop button is pressed (step S110; Yes), the control unit 110 controls the drive unit 140 to stop the vehicle from moving (step S111) and returns to step S101.

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 (e.g., 30 to 40% of the standard maximum speed) (step S113). The control unit 110 then sets the following stopping distance SD to the standard following stopping distance (step S114) and proceeds to step S107.

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

Furthermore, if the control unit 110 determines in step S103 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 (e.g., 10 degrees to 15 degrees) (step S115).

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 the maximum speed for a lateral slope (e.g., 70% to 80% of the standard maximum speed) (step S117) and proceeds to step S114.

Here, the control of the autonomous mobile device 100 according to the traveling surface will be explained using the flowchart mentioned above. The traveling surfaces on which the autonomous mobile device 100 travels include flat traveling surfaces and slopes. On flat traveling surfaces, 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). Slopes can be either vertical or horizontal, depending on the traveling direction. Vertical slopes include uphill slopes, where the elevation increases as the vehicle travels, and downhill slopes, where the elevation decreases as the vehicle travels. Furthermore, when traveling on a slope in a direction where the elevation does not change, the slope is called a horizontal slope.

The autonomous mobile device 100 may travel up a slope in three ways: (1) traveling straight up the slope, (2) traveling diagonally up the slope, (3) traveling sideways on the slope (in a direction where the elevation 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. Therefore, (2) is treated as (1), and (5) is treated as (4).

As a result of 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 Figure 8.

For example, the relationship between speed and 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 a certain size or larger, 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 0.

The relationship between the speed and the following distance when the autonomous mobile device 100 is traveling on a horizontal slope is indicated by dotted line 402. On a horizontal slope, the maximum speed MS is set to a maximum speed for horizontal slopes that is smaller than the standard maximum speed, 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 horizontal slopes (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 stop distance, the speed becomes zero. When traveling on a horizontal slope, there is a low risk of contact with the user even if the autonomous mobile device 100 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 autonomous mobile device 100 and the user is not too great, the user can use the autonomous mobile device 100 without sacrificing convenience, even when harvesting crops and placing them on the autonomous mobile device.

The relationship between the speed and the following distance when the autonomous mobile device 100 is traveling uphill is shown by the dashed-dotted line 403. On uphill slopes, the maximum speed MS is set to the maximum speed for uphill and downhill slopes, which is lower than the standard maximum speed and the maximum speed for sidehill 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 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 stop distance, the speed becomes 0. When traveling uphill, 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, convenience can be maintained when, for example, harvesting crops and placing them on the autonomous mobile device.

The relationship between speed and following distance when the slope increases while the autonomous mobile device 100 is traveling uphill is shown 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). As the following distance decreases, the speed decreases, and when the following distance reaches the standard following stop distance, the speed becomes zero. An increase in slope while traveling uphill corresponds to when 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 rotate 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, convenience can be maintained when, for example, harvesting crops and placing them on the autonomous mobile device.

The relationship between speed and following distance when the autonomous mobile device 100 is traveling on a downslope is shown by solid line 405. On a downslope, the maximum speed MS is set to the maximum speed for upslope slopes, which is smaller than the standard maximum speed or the maximum speed for sideslope slopes, and the following stop distance SD is set to the maximum speed for downslope slopes, which is larger than the standard following stop distance. Therefore, when the following distance is a certain size or larger, the speed becomes the maximum speed for upslope slopes (e.g., 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 downslope following stop distance (e.g., 2 to 2.5 times the standard following stop distance), the speed becomes 0.

The maximum speed of the autonomous mobile device 100 when traveling on a lateral slope should desirably be lower than the speed when traveling on a flat traveling surface. The speed when traveling on an uphill or downhill slope should desirably be 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.

It should be noted that there is no need to change the control when there is a downward step while traveling uphill, or an upward step while traveling downhill. Even if there is a downward 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 upward 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.

The above describes the speed control process of the autonomous mobile device 100. However, the above-described speed control process (shown in FIG. 7) is merely one example of a speed control process. In other words, in the above-described speed control process, 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 following stopping distance SD based on the magnitude relationship between these values. However, the method for setting the maximum speed MS and 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 following stopping distance SD based on the posture of the body of the autonomous mobile device 100.

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.

(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 travel. An autonomous mobile device 101 according to a second embodiment, which does not perform follow-up travel, will be described.

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 be equipped with a 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 controlled device that receives instructions wirelessly from a user located close or far away. The autonomous mobile device 101 may also be configured to travel automatically along a pre-stored route.

Also, since the autonomous mobile device 101 does not travel in a following mode, 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.

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

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

(Effects, etc.)
As described above, the control unit 110 of the autonomous mobile device 100, 101 determines the traveling surface based on the detection value detected by the attitude detection unit 130 while the device is traveling, and controls the drive 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 drive unit 140 by adjusting the following stopping distance and maximum speed, which improves the degree of freedom in controlling the drive unit 140 during autonomous traveling compared to directly stopping the drive unit 140 or directly changing the speed of the drive unit 140.

Note that each function of the autonomous mobile devices 100, 101 can also be implemented by a computer such as an ordinary PC (Personal Computer). Specifically, in the above embodiment, the speed control processing program performed by the autonomous mobile devices 100, 101 was 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, CD-ROM (Compact Disc Read Only Memory), DVD (Digital Versatile Disc), MO (Magneto-Optical Disc), memory card, or USB (Universal Serial Bus) memory, and the program may be read and installed on a computer to configure a computer that can realize each of the above-mentioned functions. Alternatively, the program may be distributed via a communications network such as the Internet, and by loading and installing the program onto a computer, a computer capable of implementing each of the above functions may be configured.

While the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and includes the inventions set forth in the claims and their equivalents. The inventions set forth in the original claims of this application are set forth below.

(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:

(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.

(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.

(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.

(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.

(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.

(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.

(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 vehicle is traveling by the drive unit;
controlling the drive unit based on the determined traveling surface;
A method for controlling an autonomous mobile device.

(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.

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... Tracking 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 (6)

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 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. 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. 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 vehicle is traveling by the drive unit;
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. 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 vehicle is traveling by the drive unit;
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. 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. 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.