Work robot

Abstract

This work robot comprises: a work unit including a work mechanism for performing work and a work motor for driving the work mechanism; a battery that is rechargeable and supplies power to the work motor; a detection unit for detecting the state of the work unit; and a control unit. The control unit is configured so as to be capable of executing abnormality determination processing in which it is determined on the basis of a detection result in the detection unit whether an abnormality has occurred in the work unit. The control unit is also configured so as to be capable of executing first abnormality handling processing in which the work robot is made to return to a charging station with the work motor stopped and charging of the battery is started. The control unit executes the first abnormality handling processing when it is determined in the abnormality determination processing that an abnormality has occurred in the work unit.

Description

Work robot

[0001] The technology disclosed in this specification relates to a working robot.

[0002] Japanese Patent Application Laid-Open Publication No. 2016-10382 discloses a work robot that performs work while moving autonomously. The work robot includes a working unit that includes a work mechanism that performs work and a work motor that drives the work mechanism, a rechargeable battery that supplies power to the work motor, and a control unit. The control unit causes the work robot to return to a charging station when the remaining charge of the battery falls below a predetermined value. The work robot can charge the battery by returning to the charging station.

[0003] When an abnormality occurs in the working unit, the control unit of a work robot may put the work robot on standby with the work motor stopped in order to resolve the abnormality. However, with this configuration, the battery cannot be charged during this standby period. As a result, even if the work robot starts working after the standby period ends, the work robot may return to the charging station prematurely due to low battery power. As a result, the work performed by the work robot may not proceed smoothly. This specification provides technology that enables the work robot to proceed smoothly with its work.

[0004] The working robot disclosed in this specification performs work while moving autonomously. The working robot includes a working unit including a working mechanism that performs work and a working motor that drives the working mechanism, a rechargeable battery that supplies power to the working motor, a detection unit that detects the state of the working unit, and a control unit. The control unit is configured to execute an abnormality determination process that determines whether an abnormality has occurred in the working unit based on the detection result of the detection unit, and a first abnormality response process that returns the working robot to a charging station with the working motor stopped and begins charging the battery. The control unit executes the first abnormality response process when the abnormality determination process determines that an abnormality has occurred in the working unit.

[0005] According to the above configuration, if an abnormality occurs in the working unit, the work robot returns to the charging station and begins charging the battery. The battery can be charged using the standby period after the abnormality occurs in the working unit. Therefore, after the standby period ends, the work robot starts work with a relatively high remaining battery power. This prevents the work robot from returning to the charging station too early after the standby period ends. Therefore, the work performed by the work robot can proceed smoothly.

[0006] It should be noted that "work" in this specification does not include "moving the work robot" or "charging the battery."

[0007] 1 is a diagram illustrating an example of use of the robotic lawnmower 2 according to Example 1. FIG. 2 is a left side view of the robotic lawnmower 2 according to Example 1. FIG. 3 is a rear view of the robotic lawnmower 2 according to Example 1. FIG. 4 is a schematic configuration diagram of the robotic lawnmower 2 according to Example 1. FIG. 5 is a flowchart of battery voltage management processing executed by the control unit 8 of the robotic lawnmower 2 according to Example 1. FIG. 6 is a flowchart of battery voltage management processing executed by the control unit 8 of the robotic lawnmower 2 according to Example 1. FIG. 7 is a diagram illustrating the time change in the voltage value of the battery 18 in the robotic lawnmower 2 according to Example 1, assuming that a decision to return to the charging station 110 is made without correcting the return threshold Vre. FIG. 8 is a diagram illustrating the time change in the voltage value of the battery 18 when the robotic lawnmower 2 according to Example 1 returns to the charging station 110 in accordance with the battery voltage management processing. FIG. 9 is a flowchart of motor burnout prevention processing executed by the control unit 8 of the robotic lawnmower 2 according to Example 1. FIG. 10 is a schematic configuration diagram of a robotic lawnmower 202 according to Example 2. 1 is a diagram showing the time change in the voltage value of the battery 18 when the robotic lawnmower 2 according to a modified example returns to the charging station 110 in accordance with the battery voltage management process. This is a schematic diagram of the configuration of a robotic lawnmower 302 according to a third embodiment. This is a diagram showing the robotic lawnmower 302 according to the third embodiment performing heavy load avoidance operation. This is a diagram showing an example of a current-counter table T stored in the memory 24 of the robotic lawnmower 302 according to the third embodiment. This is a diagram showing the time change in the detected value of the motor current detection circuit 40 (i.e., the current value flowing through the utility motor 36) and the time change in the counter C when the robotic lawnmower 302 according to the third embodiment performs lawnmowing operation. This is a diagram showing the time change in the detected value of the motor current detection circuit 40 (i.e., the current value flowing through the utility motor 36) and the time change in the counter C when the robotic lawnmower 302 according to the fourth embodiment performs lawnmowing operation. 10 is a diagram showing a schematic diagram of the time change in the detected value of the motor current detection circuit 40 (i.e., the value of the current flowing through the work motor 36) and the time change in the counter C when the robotic lawnmower 302 according to Example 5 is performing lawnmowing operation. FIG. 11 is a diagram showing an example of a current-counter table T' stored in the memory 24 of the robotic lawnmower 302 according to Example 5.

[0008] Representative, non-limiting embodiments of the present invention are described in detail below with reference to the drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Furthermore, the additional features and inventions disclosed can be used separately or in conjunction with other features and inventions to provide further improved work robots.

[0009] Furthermore, the combinations of features and steps disclosed in the following detailed description are not essential to practicing the invention in its broadest sense, but are described solely to specifically illustrate exemplary embodiments of the invention. Furthermore, the various features of the following exemplary embodiments and those described in the claims do not necessarily have to be combined in the exact embodiments described herein or in the exact order listed to provide additional and useful embodiments of the invention.

[0010] All features described in this specification and / or claims are intended to be disclosed individually and independently of one another as limitations to the specific features described in the original disclosure and claims, apart from the configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregate descriptions are intended to disclose intermediate configurations thereof as limitations to the specific features described in the original disclosure and claims.

[0011] In one or more embodiments, the control unit may determine that an abnormality has occurred in the working unit when the working motor overheats in the abnormality determination process.

[0012] If the work motor overheats, the work robot can begin work as long as the temperature of the work motor subsequently drops. With the above configuration, the battery can be charged during the waiting period until the temperature of the work motor drops after overheating. Therefore, once the temperature of the work motor has dropped sufficiently, the work robot can begin work with a relatively high remaining battery charge. This allows the work robot to proceed smoothly with its work.

[0013] In one or more embodiments, the detection unit may include a current detection unit that detects a value of a current flowing through the work motor. In the abnormality determination process, the control unit may determine whether the work motor has overheated based on the value detected by the current detection unit.

[0014] According to the above configuration, it is possible to determine whether the work motor has overheated using a simple means.

[0015] In one or more embodiments, the control unit may determine that the work motor has overheated if, during the abnormality determination process, the detection value of the current detection unit remains equal to or greater than a predetermined current value for a first predetermined time period or longer.

[0016] According to the above configuration, it is possible to determine whether the work motor has overheated using a simple means.

[0017] In one or more embodiments, after starting charging of the battery in the first anomaly response process, the control unit may terminate charging of the battery and start work by the work robot when a predetermined recovery condition is met.

[0018] According to the above configuration, after the first anomaly response process has been executed, the work robot can automatically start work without receiving an instruction to start work from the user.

[0019] In one or more embodiments, the control unit may determine that an abnormality has occurred in the working unit when the working motor overheats in the abnormality determination process. The recovery condition may include a condition in which the remaining charge of the battery is equal to or greater than a predetermined amount.

[0020] If the battery is being charged due to overheating of the work motor, it is preferable for the work robot to begin work once the temperature of the work motor has sufficiently dropped. For example, if the battery continues to be charged until the remaining battery charge reaches a predetermined level or more, it can be estimated that a certain amount of time has passed since the overheating occurred, and the temperature of the work motor can be considered to have dropped sufficiently. With the above configuration, the work robot begins work after the battery continues to be charged until the remaining battery charge reaches a predetermined level or more. Therefore, the work robot can begin work once the temperature of the work motor has sufficiently dropped.

[0021] In one or more embodiments, the control unit may determine that an abnormality has occurred in the working unit if the work motor overheats in the abnormality determination process, and the recovery condition may include a condition in which a second predetermined time has elapsed since the work motor was determined to have overheated in the abnormality determination process.

[0022] The temperature of the work motor is considered to have dropped sufficiently after a certain amount of time has passed since overheating occurred. With the above configuration, the work robot begins work after a certain amount of time has passed since overheating occurred. Therefore, the work robot can begin work when the temperature of the work motor has dropped sufficiently.

[0023] In one or more embodiments, the detection unit may include a temperature sensor that detects the temperature of the work motor. The control unit may determine that an abnormality has occurred in the work unit if the work motor overheats during the abnormality determination process. The recovery condition may include the temperature of the work motor detected by the temperature sensor being equal to or lower than a first predetermined temperature.

[0024] According to the above configuration, the work robot can start working after the temperature of the work motor has dropped sufficiently.

[0025] In one or more embodiments, the control unit may be further configured to execute a second anomaly response process that stops the work motor and causes the work robot to wait without returning to the charging station. The operation mode of the work robot may be set to one of a plurality of modes, including a first mode in which the control unit executes the first anomaly response process when it is determined in the anomaly determination process that an abnormality has occurred in the work unit, and a second mode in which the control unit executes the second anomaly response process when it is determined in the anomaly determination process that an abnormality has occurred in the work unit.

[0026] Some abnormalities related to the working unit require the user to go to the location where the abnormality occurred. When such an abnormality occurs, it is preferable to have the work robot wait at the location where the abnormality occurred rather than returning to the charging station. Therefore, it is preferable that the response of the work robot after an abnormality occurs in the working unit be switchable between returning to the charging station and waiting without returning to the charging station. According to the above configuration, the operation modes of the work robot include a first mode in which the work robot returns to the charging station after an abnormality occurs in the working unit, and a second mode in which the work robot waits without returning to the charging station after an abnormality occurs in the working unit. Therefore, by changing the operation mode setting, it is possible to switch the response of the work robot after an abnormality occurs in the working unit between returning to the charging station and waiting without returning to the charging station.

[0027] In one or more embodiments, the operational mode of the work robot may be changeable by a user.

[0028] According to the above configuration, the user can change the operation mode of the work robot to change how the work robot responds after an abnormality occurs in the working unit.

[0029] In one or more embodiments, the control unit may include a counter. The control unit may vary the value of the counter by a first variation amount when a first counter variation condition based on the detection result of the detection unit is satisfied. The control unit may vary the value of the counter by a second variation amount when a second counter variation condition based on the detection result of the detection unit is satisfied. The control unit may determine whether the work motor has overheated based on the value of the counter.

[0030] According to the above configuration, the control unit can determine whether the work motor has overheated based on an index (counter value) that depends on multiple conditions. For example, a counter can be used as an index representing the temperature of the work motor. In this case, the control unit can increase the counter value when a condition that induces an increase in the temperature of the work motor is met, and decrease the counter value when a condition that induces a decrease in the temperature of the work motor is met. The control unit can then determine that the work motor has overheated when the counter value increases. In this way, the control unit can consider multiple conditions in a composite manner when determining whether the work motor has overheated. This allows the control unit to accurately determine whether the work motor has overheated.

[0031] In one or more embodiments, the detector may include a current detector that detects a value of a current flowing through the industrial motor. The first counter fluctuation condition may be that the detected value of the current detector is within a first numerical range. The second counter fluctuation condition may be that the detected value of the current detector is within a second numerical range.

[0032] According to the above configuration, the control unit can accurately determine whether the work motor has overheated by comprehensively considering multiple conditions related to the value of the current flowing through the work motor. For example, if a counter is used as an indicator of the temperature of the work motor, the control unit can increase or decrease the counter value depending on the magnitude of the current flowing through the work motor. The control unit can then determine that the work motor has overheated when the counter value increases. This is because, when the current flowing through the work motor is large, the amount of heat generated by the work motor increases, causing the temperature of the work motor to rise. On the other hand, when the current flowing through the work motor is small (or no current is flowing through the work motor), the amount of heat generated by the work motor decreases, causing the temperature of the work motor to drop.

[0033] In one or more embodiments, one of the first variation and the second variation may be a positive value, and the other of the first variation and the second variation may be a negative value. The control unit may determine that the work motor has overheated when the value of the counter is equal to or greater than a predetermined first determination threshold.

[0034] According to the above configuration, the control unit determines that the work motor has overheated when the counter value increases. As a result, for example, by using the counter as an index representing the temperature of the work motor, it is possible to determine that the work motor has overheated when the counter value (work motor temperature) increases.

[0035] In one or more embodiments, the control unit may determine that the overheating of the work motor has been resolved if the value of the counter falls below a predetermined second determination threshold after determining that the work motor has overheated.

[0036] According to the above configuration, after determining that the work motor has overheated, the control unit determines that the overheating of the work motor has been resolved when the counter value decreases. As a result, for example, by using the counter as an index representing the temperature of the work motor, it is possible to determine that the overheating of the work motor has been resolved when the counter value (work motor temperature) decreases.

[0037] In one or more embodiments, after starting charging of the battery in the first anomaly response process, the control unit may terminate charging of the battery and start work by the work robot when a predetermined recovery condition is met. The recovery condition may include the control unit determining that overheating of the work motor has been resolved.

[0038] According to the above configuration, the working robot can automatically resume work that was interrupted due to overheating of the working motor.

[0039] In one or more embodiments, after starting charging of the battery in the first anomaly response process, if a predetermined recovery condition is met, the control unit may terminate charging of the battery and start work by the work robot. The control unit may not need to initialize the value of the counter during a work interruption period associated with charging the battery.

[0040] It is also conceivable to configure the counter value to be initialized (e.g., reset to zero) during a work interruption. However, there are cases where it is desirable to refer to the counter value before the work interruption during the work interruption and / or after work is resumed. For example, there are cases where it is desirable to determine whether the overheating of the work motor has been resolved based on the counter value before the work interruption. With the above configuration, since the counter value is not initialized during the work interruption, it is possible to refer to the counter value before the work interruption during the work interruption and / or after work is resumed.

[0041] Example 1 As shown in FIG. 1 , the work robot of this example is, for example, a robotic lawnmower 2 used within a site 100 covered with grass. Site 100 includes, for example, a house 102, a pond 104, a road 106, and a fence 108. Site 100 also includes a charging station 110 connected to an external power source (e.g., a commercial power source) and a wire 112 defining a work area WA for the robotic lawnmower 2. The work area WA is the area enclosed by wire 112. The work area WA for the robotic lawnmower 2 is divided into a main area MA, which includes the charging station 110, and a sub-area SA, which does not include the charging station 110. The robotic lawnmower 2 detects the position of wire 112 and autonomously moves within the work area WA (main area MA in the example of FIG. 1 ) within which the robotic lawnmower 2 is located. This allows the robotic lawnmower 2 to perform lawn mowing work while moving over the lawn, avoiding the house 102, pond 104, road 106, and fence 108.

[0042] 2, 3, and 4, the robotic lawnmower 2 includes a robot body 4, a power supply unit 6, a control unit 8, an operation unit 10, a moving unit 12, a working unit 14, and a detection unit 16. The power supply unit 6, the control unit 8, the operation unit 10, the moving unit 12, the working unit 14, and the detection unit 16 are each supported by the robot body 4.

[0043] The power supply unit 6 shown in FIG. 4 can supply power to each component of the robotic lawnmower 2 via a power supply circuit 26 of the control unit 8. The power supply unit 6 includes a rechargeable battery 18, such as a lithium-ion battery, and a charging interface 20 electrically connected to the battery 18. The battery 18 has a nominal capacity of, for example, 5.0 Ah. The battery 18 has a nominal voltage of, for example, 18 V. The robotic lawnmower 2 can be docked to a charging station 110 (see FIG. 1) via the charging interface 20. When the robotic lawnmower 2 is docked to the charging station 110, the battery 18 can be charged using power supplied from the charging station 110. The battery 18 may be charged via wired charging. Specifically, the battery 18 may be charged by connecting a terminal on the charging station 110 to a terminal on the charging interface 20. Alternatively, the battery 18 may be charged via wireless charging. Specifically, the battery 18 may be charged by generating an induced electromotive force in a power receiving coil provided in the charging interface 20 using a power transmitting coil provided in the charging station 110 .

[0044] The control unit 8 includes a processor 22, a memory 24, and a power supply circuit 26. The memory 24 includes ROM, RAM, etc. The memory 24 stores a program for autonomously controlling the robotic lawnmower 2. The processor 22 is configured to autonomously control the robotic lawnmower 2 in accordance with the program stored in the memory 24. The memory 24 also stores settings related to the robotic lawnmower 2 (e.g., the mowing height of the lawn). The settings related to the robotic lawnmower 2 include settings related to the operating mode of the robotic lawnmower 2. The operating mode of the robotic lawnmower 2 is set to one of a number of modes, including a main-area compatible mode corresponding to the main area MA (see FIG. 1) and a sub-area compatible mode corresponding to the sub-area SA (see FIG. 1).

[0045] The operation unit 10 is provided, for example, on the exterior of the robot body 4 (see FIG. 2 ) and includes switches and the like that can be operated by the user. The user can perform various operations related to the robotic lawnmower 2 via the operation unit 10. The various operations referred to here include, for example, operations to turn the main power supply of the robotic lawnmower 2 on and off, operations to input instructions to the robotic lawnmower 2, and operations to change settings related to the robotic lawnmower 2.

[0046] The moving unit 12 includes a pair of left and right casters 28L, 28R, a pair of left and right drive wheels 30L, 30R, and a pair of left and right moving motors 32L, 32R. The moving motors 32L, 32R are, for example, brushless DC motors. The drive wheels 30L, 30R are coupled to the output shafts of the moving motors 32L, 32R, respectively. As shown in FIGS. 2 and 3 , the robotic lawnmower 2 is placed on the ground G with the casters 28L, 28R and the drive wheels 30L, 30R in contact with the ground G. The moving unit 12 can move the robot body 4 forward, backward, and turn by operating the moving motors 32L, 32R (see FIG. 4 ) to rotate the drive wheels 30L, 30R.

[0047] As shown in FIG. 2 , the working unit 14 includes a cutting blade 34 and a work motor 36. The cutting blade 34 is a rotary blade formed in a generally circular disk shape. The work motor 36 is, for example, a brushless DC motor. The work motor 36 is supported by the robot body 4 with its output shaft tilted from front to rear as it extends from top to bottom. The cutting blade 34 is connected to the output shaft of the work motor 36. The working unit 14 can cut the grass by operating the work motor 36 to rotate the cutting blade 34.

[0048] As shown in FIG. 4, the detection unit 16 includes a wire detection sensor 38, a motor current detection circuit 40, and a battery voltage detection circuit 42.

[0049] The wire detection sensor 38 is a sensor for detecting the wire 112 (see FIG. 1). The wire detection sensor 38 is, for example, a magnetic sensor. In this embodiment, a predetermined electrical signal is applied to the wire 112 from the charging station 110 (see FIG. 1). As a result, a magnetic signal corresponding to the predetermined electrical signal is generated around the wire 112. The wire detection sensor 38 is configured to detect this magnetic signal and output it to the processor 22. Based on the signal pattern and signal strength of the magnetic signal detected by the wire detection sensor 38, the processor 22 can determine whether the robotic lawnmower 2 is approaching the wire 112, whether the robotic lawnmower 2 is positioned on the wire 112, etc.

[0050] The motor current detection circuit 40 is configured to detect the current values ​​supplied to the travel motors 32L, 32R and the work motor 36, and output the detected values ​​to the processor 22.

[0051] The battery voltage detection circuit 42 is configured to detect the voltage value of the battery 18 and output the detected voltage value to the processor 22. This allows the processor 22 to grasp the voltage value of the battery 18.

[0052] The following describes the operations or processes executed by the control unit 8 (specifically, the processor 22).

[0053] (Lawnmowing Operation) Lawnmowing operation is the main operation of the robotic lawnmower 2 (see FIG. 1). Lawnmowing operation begins, for example, when the robotic lawnmower 2 is powered on and a command to start lawnmowing operation is issued via the operation unit 10 (see FIG. 4). When lawnmowing operation begins, the control unit 8 confirms that no abnormalities have occurred in the robotic lawnmower 2 and then begins mowing the lawn with the robotic lawnmower 2. Specifically, the control unit 8 drives the cutting blade 34 (see FIG. 2) with the work motor 36 (see FIG. 2) and the drive wheels 30L, 30R (see FIG. 2) with the travel motors 32L, 32R (see FIG. 4) to cut the grass. During lawnmowing operation, the control unit 8 may interrupt or end lawnmowing operation with the robotic lawnmower 2 and perform another operation depending on the situation. The control unit 8 ends lawnmowing operation when a predetermined operation end condition is met. The operation end condition here includes, for example, the time that has elapsed since the start of the lawn mowing operation reaching a time that is preset by the user.

[0054] (Battery Voltage Management Process; Figures 5 and 6) The battery voltage management process is performed when the operating mode of the robotic lawnmower 2 (see Figure 1) is set to the main area mode, and is repeatedly performed while the aforementioned lawnmower operation is being performed. The battery voltage management process is performed when the voltage of the battery 18 is low, and returns the robotic lawnmower 2 to the charging station 110 (see Figure 1) to charge the battery 18 (see Figure 4). The memory 24 (see Figure 4) pre-stores the voltage of the battery 18 (return threshold Vre) that must be maintained in order for the robotic lawnmower 2 to return to the charging station 110. In this embodiment, the return threshold Vre is set to 17.5 V. The battery voltage management process mainly includes a process for correcting the return threshold Vre and a process for returning the robotic lawnmower 2 to the charging station 110 based on the corrected return threshold Vre'.

[0055] As shown in Fig. 5, in S2, the control unit 8 determines whether the correction flag is on. The correction flag is a status register included in the memory 24. The correction flag is off when the corrected feedback threshold value Vre' has not been acquired. If the correction flag is off (NO), the process proceeds to S4.

[0056] In S4, the control unit 8 determines whether the travel motors 32L, 32R (see FIG. 4) are stopped. While the robotic lawnmower 2 is mowing, the travel motors 32L, 32R are generally operating, but the travel motors 32L, 32R may stop, for example, when the robotic lawnmower 2 changes direction. If the travel motors 32L, 32R are not stopped (NO), the process proceeds to S6.

[0057] In S6, the control unit 8 determines whether the operation duration of the movement motors 32L, 32R is equal to or greater than a first upper limit time (e.g., 2 minutes). The operation duration of the movement motors 32L, 32R here refers to the time elapsed since the movement motors 32L, 32R most recently started operating. If the operation duration of the movement motors 32L, 32R is less than the first upper limit time (NO), the process returns to S2. If the operation duration of the movement motors 32L, 32R is equal to or greater than the first upper limit time (YES), the process proceeds to S8.

[0058] In S8, the control unit 8 stops the movement motors 32L and 32R.

[0059] If it is determined in S4 that the travel motors 32L, 32R are stopped (YES), or after S8, the process proceeds to S10. In S10, the control unit 8 acquires the detection value of the battery voltage detection circuit 42 (see FIG. 4) as a determination voltage value and determines whether the acquired determination voltage value is equal to or less than the feedback threshold Vre. While the robotic lawnmower 2 is performing lawnmowing work, the work motor 36 (see FIG. 4) generally does not stop. Therefore, in S10, the voltage value of the battery 18 when the work motor 36 is operating and the travel motors 32L, 32R are stopped is acquired as the determination voltage value. If the determination voltage value exceeds the feedback threshold Vre (NO), the process returns to S2. If the determination result in S10 is NO after the travel motors 32L, 32R are stopped in S8, the control unit 8 restarts the travel motors 32L, 32R. If the determination voltage value is equal to or less than the feedback threshold value Vre (YES), the process proceeds to S12.

[0060] In S12, the control unit 8 acquires the detection value of the battery voltage detection circuit 42 as the first-stage voltage value V1. In S12, the voltage value of the battery 18 when the work motor 36 is operating and the travel motors 32L, 32R are stopped is acquired as the first-stage voltage value V1. After S12, the process proceeds to S14.

[0061] In S14, the control unit 8 stops the work motor 36 in addition to the travel motors 32L, 32R. In other words, the control unit 8 suspends lawn mowing by the robotic lawnmower 2. The control unit 8 then waits for a predetermined time (e.g., two seconds) with the work motor 36 and travel motors 32L, 32R suspended. This allows the voltage of the battery 18 to recover by the amount of voltage drop caused by the internal resistance of the work motor 36 compared to immediately before lawn mowing was suspended. After S14, the process proceeds to S16.

[0062] In S16, the control unit 8 interrupts lawn mowing by the robotic lawnmower 2 and acquires the detection value of the battery voltage detection circuit 42 as the second-stage voltage value V2. In S16, the voltage value of the battery 18 when the work motor 36 and the travel motors 32L, 32R are stopped is acquired as the second-stage voltage value V2. After acquiring the second-stage voltage value V2, the control unit 8 restarts the travel motors 32L, 32R and the work motor 36 to resume lawn mowing by the robotic lawnmower 2. After S16, the process proceeds to S18.

[0063] In S18, the control unit 8 calculates the recovery voltage value Vdiff by subtracting the first-stage voltage value V1 from the second-stage voltage value V2. Therefore, the recovery voltage value Vdiff = V2 - V1. After S18, the process proceeds to S20.

[0064] In S20, the control unit 8 determines whether the recovery voltage value Vdiff calculated in S18 is equal to or less than a predetermined lower limit value (e.g., 0.1 V). If the recovery voltage value Vdiff is equal to or less than the lower limit value (YES), the process proceeds to S22.

[0065] In S22, the control unit 8 corrects the recovery voltage value Vdiff to 0V.

[0066] If it is determined in S20 that the recovery voltage value Vdiff is not equal to or less than the lower limit (NO), the process proceeds to S24. In S24, the control unit 8 determines whether the recovery voltage value Vdiff calculated in S18 is equal to or greater than a predetermined upper limit (e.g., 0.5 V). If the recovery voltage value Vdiff is equal to or less than the upper limit (YES), the process proceeds to S26.

[0067] In S26, the control unit 8 corrects the recovery voltage value Vdiff to the same value as the upper limit value (for example, 0.5 V) used in the determination in S24.

[0068] If it is determined in S24 that the recovery voltage value Vdiff is not equal to or less than the upper limit (NO), the process proceeds to S28 after S22 or S26. In S28, the control unit 8 corrects the feedback threshold value Vre by subtracting the recovery voltage value Vdiff from the feedback threshold value Vre. Therefore, the corrected feedback threshold value Vre' = Vre - Vdiff. The control unit 8 also stores the corrected feedback threshold value Vre' in the memory 24 and switches the correction flag on. After S28, the process returns to S2.

[0069] If it is determined in S2 that the correction flag is on (YES), the process proceeds to S30 shown in Fig. 6. In S30, the control unit 8 determines whether the movement motors 32L, 32R are stopped. If the movement motors 32L, 32R are not stopped (NO), the process proceeds to S32.

[0070] In S32, the control unit 8 determines whether the operation duration of the movement motors 32L, 32R is equal to or greater than a second upper limit time (e.g., one minute). If the operation duration of the movement motors 32L, 32R is less than the second upper limit time (NO), the process returns to S2 (see FIG. 5). If the operation duration of the movement motors 32L, 32R is equal to or greater than the second upper limit time (YES), the process proceeds to S34.

[0071] In S34, the control unit 8 stops the movement motors 32L and 32R.

[0072] If it is determined in S30 that the travel motors 32L, 32R are stopped (YES), or after S34, the process proceeds to S36. In S36, the control unit 8 acquires the detection value of the battery voltage detection circuit 42 as a determination voltage value and determines whether the acquired determination voltage value is equal to or less than the corrected feedback threshold Vre'. Note that in S36, the voltage value of the battery 18 when the work motor 36 is operating and the travel motors 32L, 32R are stopped is acquired as the determination voltage value. If the determination voltage value exceeds the corrected feedback threshold Vre' (NO), the process returns to S2 (see FIG. 5). Note that if the determination result in S36 is NO after the travel motors 32L, 32R are stopped in S34, the control unit 8 restarts the travel motors 32L, 32R. If the determination voltage value is equal to or less than the corrected feedback threshold Vre' (YES), the process proceeds to S38.

[0073] In S38, the control unit 8 ends the lawn mowing operation by the robotic lawnmower 2 and returns the robotic lawnmower 2 to the charging station 110. Specifically, with the work motor 36 stopped, the control unit 8 operates the transport motors 32L, 32R so that the robotic lawnmower 2 follows the wire 112 to the charging station 110. After S38, the process proceeds to S40.

[0074] In S40, the control unit 8 docks the robotic lawnmower 2 to the charging station 110 and begins charging the battery 18. In response to the robotic lawnmower 2 docking to the charging station 110, the control unit 8 also erases the corrected feedback threshold Vre' from the memory 24 and switches the correction flag to OFF. Note that the corrected feedback threshold Vre' stored in the memory 24 is erased from the memory 24 even if the robotic lawnmower 2 docks to the charging station 110 regardless of S40 of the battery voltage management process. Similarly, note that the correction flag is switched to OFF even if the robotic lawnmower 2 docks to the charging station 110 regardless of S40 of the battery voltage management process. After S40, the process proceeds to S42.

[0075] In S42, the control unit 8 determines whether a predetermined normal return condition is met. The normal return condition includes, for example, the voltage value of the battery 18 detected by the battery voltage detection circuit 42 being equal to or greater than a predetermined value (e.g., 20 V). If the normal return condition is not met (NO), the process repeats S42. If the normal return condition is met (YES), the process proceeds to S44.

[0076] In S44, the control unit 8 stops charging the battery 18, undocks the robotic lawnmower 2 from the charging station 110, and restarts the travel motors 32L, 32R and the work motor 36. In other words, the control unit 8 resumes lawnmowing work with the robotic lawnmower 2. After S44, the battery voltage management process shown in Figures 5 and 6 ends.

[0077] Advantages of Battery Voltage Management Processing The robotic lawnmower 2 operates the work motor 36 (see FIG. 4) while mowing, but stops the work motor 36 while returning to the charging station 110 (see FIG. 1). Therefore, when the robotic lawnmower 2 finishes mowing and begins its return journey, the voltage of the battery 18 (see FIG. 4) recovers by the amount of voltage drop caused by the internal resistance of the work motor 36. If, as shown in FIG. 7 , the robotic lawnmower 2 begins its return journey just as the voltage of the battery 18 reaches the return threshold Vre while the robotic lawnmower 2 is mowing, the voltage of the battery 18 recovers immediately thereafter and significantly exceeds the return threshold Vre. Therefore, the robotic lawnmower 2 may return to the charging station 110 even though the battery 18 still has enough charge remaining to allow the robotic lawnmower 2 to continue mowing. This causes the robotic lawnmower 2 to frequently return to the charging station 110, which increases the proportion of time the robotic lawnmower 2 is not mowing (for example, time spent returning to the charging station 110 or charging the battery 18) compared to the time the robotic lawnmower 2 is mowing. As a result, the work efficiency of the robotic lawnmower 2 may decrease.

[0078] As shown in FIG. 8 , the battery voltage management process identifies the voltage drop due to the internal resistance of the work motor 36 as the recovery voltage value Vdiff. The recovery voltage value Vdiff is then subtracted from the predetermined feedback threshold Vre to obtain the feedback threshold Vre'. The robotic lawnmower 2 then begins returning when the voltage of the battery 18 while the robotic lawnmower 2 is mowing reaches the feedback threshold Vre'. This ensures that the voltage of the battery 18 immediately after the robotic lawnmower 2 begins returning recovers to a value close to the feedback threshold Vre. Therefore, the robotic lawnmower 2 can be returned to the charging station 110 when the remaining charge of the battery 18 has fallen to the point where the robotic lawnmower 2 can continue mowing. This minimizes the frequency with which the robotic lawnmower 2 returns to the charging station 110, thereby reducing the proportion of time the robotic lawnmower 2 is not mowing relative to the time it is mowing. As a result, the operating efficiency of the robotic lawnmower 2 can be improved.

[0079] (Motor burnout prevention process; Figure 9) The motor burnout prevention process is repeatedly executed while the robotic lawnmower 2 (see Figure 1) is performing the aforementioned lawnmowing operation, regardless of the operating mode it is in. Note that the motor burnout prevention process is also executed at the stage before the robotic lawnmower 2 begins mowing, when it is checked to ensure that no abnormalities have occurred in the robotic lawnmower 2.

[0080] In S52, the control unit 8 determines whether the work motor 36 (see FIG. 2) has overheated. Overheating here refers to the work motor 36 reaching an excessively high temperature (e.g., a temperature of 150°C or higher), a temperature that could cause the work motor 36 to burn out (melting the winding coating and causing a short circuit), or a temperature that could affect the lifespan of the work motor 36. For example, if the detected value of the motor current detection circuit 40 (see FIG. 4) (i.e., the current flowing through the work motor 36) remains above a first current value (e.g., 5 A) for a first duration (e.g., 55 minutes) or longer, the control unit 8 estimates that the temperature of the work motor 36 has become excessively high and determines that the work motor 36 has overheated. The control unit 8 also determines that the work motor 36 has overheated if the detected value of the motor current detection circuit 40 is equal to or greater than a second current value (e.g., 6 A) higher than the first current value and continues for a second duration (e.g., 22 minutes) or longer that is shorter than the first duration. The control unit 8 also determines that the work motor 36 has overheated if the detected value of the motor current detection circuit 40 is equal to or greater than a third current value (e.g., 7 A) higher than the second current value and continues for a third duration (e.g., 10 minutes) or longer that is shorter than the second duration. If the work motor 36 has overheated (YES), the process proceeds to S54.

[0081] In S54, the control unit 8 determines whether the robotic lawnmower 2 is within the main area MA (see FIG. 1). If the operating mode of the robotic lawnmower 2 is set to the main area compatible mode, the control unit 8 determines that the robotic lawnmower 2 is within the main area MA (YES). If the operating mode of the robotic lawnmower 2 is set to a mode other than the main area compatible mode, the control unit 8 determines that the robotic lawnmower 2 is not within the main area MA (NO). If the robotic lawnmower 2 is within the main area MA (YES), processing proceeds to S56.

[0082] In S56, the control unit 8 returns the robotic lawnmower 2 to the charging station 110 (see FIG. 1). Specifically, while stopping the work motor 36, the control unit 8 operates the transport motors 32L, 32R (see FIG. 4) so ​​that the robotic lawnmower 2 follows the wire 112 to the charging station 110. The control unit 8 also operates a light source device and buzzer (not shown) provided on the robot main body 4 to notify the robotic lawnmower 2 of an abnormality by sound or light. After S56, the process proceeds to S58.

[0083] In S58, the control unit 8 docks the robotic lawnmower 2 to the charging station 110 and begins charging the battery 18 (see FIG. 4). Note that the control unit 8 continues to notify the user that an abnormality has occurred even after starting charging of the battery 18. After S58, the process proceeds to S60.

[0084] In S60, the control unit 8 determines whether a predetermined first abnormality recovery condition is met. In this embodiment, the first abnormality recovery condition includes a condition in which the temperature of the work motor 36 is expected to return to a normal temperature (e.g., a temperature of 40°C or less). For example, the first abnormality recovery condition includes the voltage of the battery 18 detected by the battery voltage detection circuit 42 (see FIG. 4) reaching a predetermined value (e.g., 20 V) or higher. This is because if the battery 18 continues to be charged for a certain period of time, it can be estimated that the temperature of the work motor 36 will have dropped to a normal temperature. Alternatively, the first abnormality recovery condition includes the time elapsed since the most recent execution of S52, in which it was determined that the work motor 36 had overheated, reaching a predetermined time (e.g., 20 minutes). If the first abnormality recovery condition is not met (NO), the process repeats S60. If the first abnormality recovery condition is met (YES), the process proceeds to S62.

[0085] In S62, the control unit 8 stops charging the battery 18, undocks the robotic lawnmower 2 from the charging station 110, and restarts the travel motors 32L, 32R and the work motor 36. In other words, the control unit 8 resumes mowing work with the robotic lawnmower 2. The control unit 8 also stops the light source device and buzzer (not shown) that are in operation, and ends the abnormality notification.

[0086] If it is determined in S54 that the robotic lawnmower 2 is not within the main area MA (NO), processing proceeds to S64. In S64, the control unit 8 stops the work motor 36 and the travel motors 32L, 32R, and causes the robotic lawnmower 2 to wait in place. The control unit 8 also activates a light source device and buzzer (not shown) provided on the robot body 4 to alert the user by sound or light that an abnormality has occurred. After S64, processing proceeds to S66.

[0087] In S66, the control unit 8 determines whether a predetermined second abnormality recovery condition is met. In this embodiment, the second abnormality recovery condition includes a condition in which the temperature of the work motor 36 (see FIG. 2) is expected to return to a normal temperature (e.g., a temperature of 40°C or less). For example, the second abnormality recovery condition includes a condition in which a predetermined time (e.g., 20 minutes) has elapsed since the work motor 36 was determined to have overheated in the most recent execution of S52. If the second abnormality recovery condition is not met (NO), the process repeats S66. Therefore, the robotic lawnmower 2 continues to wait in place while the second abnormality recovery condition is not met (YES), the process proceeds to S68.

[0088] In S68, the control unit 8 ends the standby state and restarts the travel motors 32L, 32R and the work motor 36. That is, the control unit 8 resumes lawn mowing work with the robotic lawnmower 2. The control unit 8 also stops the light source device and buzzer (not shown) that are in operation, and ends the abnormality notification.

[0089] If it is determined in S52 that the work motor 36 is not overheating (NO), the motor burnout prevention process shown in FIG. 9 ends after S62 or S68.

[0090] 10, the work robot of this embodiment is a robotic lawnmower 202 that has substantially the same components as the robotic lawnmower 2 of embodiment 1. Components that are common between the robotic lawnmower 2 and the robotic lawnmower 202 are given the same reference numerals, and descriptions thereof will be omitted.

[0091] The robotic lawnmower 202 has a detection unit 204 instead of the detection unit 16 (see FIG. 4 ) of the first embodiment. The detection unit 204 differs from the detection unit 16 in that it has a motor temperature sensor 206. The motor temperature sensor 206 is configured to detect the temperature of the work motor 36 and output the temperature to the processor 22 of the control unit 8. The temperature of the work motor 36 here includes, for example, the temperature of the stator of the work motor 36, the temperature of the Hall sensor provided on the work motor 36, and the temperature of the motor driver board that controls the rotation of the work motor 36.

[0092] In this embodiment, the control unit 8 also determines that the work motor 36 has overheated when the temperature of the work motor 36 detected by the motor temperature sensor 206 is excessively high (e.g., 150°C or higher) in S52 of the motor burnout prevention process shown in Fig. 9. The first abnormality recovery condition used in S60 of the motor burnout prevention process further includes the temperature of the work motor 36 detected by the motor temperature sensor 206 returning to a normal temperature (e.g., 40°C or lower). The second abnormality recovery condition used in S66 of the motor burnout prevention process further includes the temperature of the work motor 36 detected by the motor temperature sensor 206 returning to a normal temperature (e.g., 40°C or lower).

[0093] (Variations of Examples 1 and 2) The work robot may be a robot other than the robotic lawnmower 2, 202. For example, the work robot may be a robot vacuum cleaner equipped with a brush and / or suction mechanism for collecting dust and other debris. In this case, the work motor 36 may be used as a motor for driving the brush and / or suction mechanism. The work robot may also be a rebar binding robot equipped with a rebar binding mechanism for binding together the intersections of multiple rebars. In this case, the work motor 36 may be used as a motor for driving the rebar binding mechanism.

[0094] At least one of the working motor 36 and the moving motors 32L, 32R may be a motor other than a brushless DC motor (for example, a DC motor with brushes).

[0095] The moving unit 12 may be provided with a pair of left and right crawlers instead of the casters 28L, 28R and the drive wheels 30L, 30R. The moving motors 32L, 32R may be used as motors for driving the pair of left and right crawlers.

[0096] The battery 18 may be a rechargeable battery 18 other than a lithium-ion battery (e.g., a nickel-metal hydride battery or a nickel-cadmium battery). The nominal capacity and nominal voltage of the battery 18 may be changed as appropriate. The nominal capacity of the battery 18 may be, for example, 3.0 Ah. The nominal voltage of the battery 18 may be, for example, 36 V.

[0097] The setting of the feedback threshold Vre may be changed as appropriate. The setting of the feedback threshold Vre may be changeable by the user via the operation unit 10, or may not be changeable by the user via the operation unit 10.

[0098] 5 and 6, the control unit 8 may skip S10 and execute S12 after S8. That is, the control unit 8 may be configured to execute S12 and subsequent processes after S8 regardless of the remaining charge of the battery 18.

[0099] In the determination process of S10 of the battery voltage management process, the control unit 8 may use a threshold value Vth (e.g., Vth = 17.6 V) different from the feedback threshold value Vre. That is, in S10, the control unit 8 may obtain the detection value of the battery voltage detection circuit 42 as the determination voltage value and determine whether the obtained determination voltage value is equal to or lower than the threshold value Vth. In this example, as shown in FIG. 11 , the voltage drop due to the internal resistance of the work motor 36 is identified as the recovery voltage value Vdiff. As a result, the feedback threshold value Vre' is obtained in a manner similar to the embodiment, and the voltage of the battery 18 immediately after the robotic lawnmower 2, 202 begins to return to a value close to the feedback threshold value Vre. Therefore, the robotic lawnmower 2, 202 can be returned to the charging station 110 with a moderate remaining charge in the battery 18.

[0100] In the battery voltage management process shown in FIGS. 5 and 6 , after determining NO in S20, the control unit 8 may skip S24 and execute S28. As a result, the recovery voltage value Vdiff may be allowed to exceed the upper limit value. Alternatively, after S18, the control unit 8 may skip S20 and execute S24. As a result, the recovery voltage value Vdiff may be allowed to be a value equal to or less than the lower limit value (a value greater than 0). Alternatively, after S18, the control unit 8 may skip S20, S22, S24, and S26 and execute S28. As a result, both the recovery voltage value Vdiff exceeding the upper limit value and the recovery voltage value Vdiff being a value equal to or less than the lower limit value (a value greater than 0) may be allowed.

[0101] In S28 of the battery voltage management process, the control unit 8 may correct the feedback threshold value Vre by multiplying the recovery voltage value Vdiff by a predetermined coefficient k (for example, k = 0.8) and subtracting the result from the feedback threshold value Vre. Therefore, Vre' = Vre - k × Vdiff may be obtained.

[0102] In the battery voltage management process, the control unit 8 may determine whether to return the robotic lawnmower 2 to the charging station 110 without calculating the recovery voltage value Vdiff or correcting the return threshold value Vre. For example, the control unit 8 may obtain the first-stage voltage value V1 in S12, obtain the second-stage voltage value V2 in S16, and then determine whether the detection value (determination voltage value) of the battery voltage detection circuit 42 is equal to or less than 2×V1−V2. If the determination voltage value is equal to or less than 2×V1−V2 (YES), the control unit 8 may execute the process from S38 onward. If the determination voltage value is greater than 2×V1−V2 (NO), the control unit 8 may restart the battery voltage management process from the start. In this example, the correction flag may always be off.

[0103] In the battery voltage management process, after determining NO in S2, the control unit 8 may skip S4, S6, and S8 and execute S10. As a result, the process from S10 onward may be executed while the travel motors 32L and 32R are not stopped (i.e., while the travel motors 32L and 32R are operating). However, it is preferable that the operating status (operation / stop) of the travel motors 32L and 32R not be switched during the process of executing S10, S12, S14, and S16.

[0104] In the battery voltage management process, after determining YES in S2, the control unit 8 may skip S30, S32, and S34 and execute S36. As a result, the processes from S36 onward may be executed while the travel motors 32L, 32R are not stopped (i.e., while the travel motors 32L, 32R are operating).

[0105] In the first and second embodiments, the control unit 8 is configured to stop the operating work motor 36 and observe changes in the voltage value of the battery 18 in S12, S14, and S16 of the battery voltage management process. That is, the work motor 36 is the target motor as defined in this specification, and the transport motors 32L, 32R are the non-target motors as defined in this specification. In another embodiment, the control unit 8 may be configured to stop the operating work motor 36 and the transport motors 32L, 32R in S12, S14, and S16 and observe changes in the voltage value of the battery 18. That is, both the work motor 36 and the transport motors 32L, 32R may be target motors. In yet another embodiment, the control unit 8 may be configured to stop the operating transport motors 32L, 32R in S12, S14, and S16 and observe changes in the voltage value of the battery 18. That is, the moving motors 32L and 32R may be the target motors, and the working motor 36 may be the non-target motor.

[0106] 9 , after starting charging of the battery 18 in S58, the control unit 8 may end the motor burnout prevention process and terminate the ongoing lawnmowing operation instead of executing the processes from S60 onwards. The control unit 8 may then end charging of the battery 18 when the battery 18 is fully charged, for example, and place the robotic lawnmower 2, 202 on standby at the charging station 110. In other words, the control unit 8 may be configured not to automatically resume lawnmowing after an abnormality occurs in the robotic lawnmower 2, 202 (overheating of the work motor 36).

[0107] The detector 16, 204 may be capable of detecting various abnormalities related to the working unit 14, not limited to overheating of the work motor 36. An abnormality related to the working unit 14 here includes, for example, an excessive load being placed on the work motor 36 or wear of the cutting blade 34 to the point where replacement is required. When the detector 16, 204 detects an abnormality related to the working unit 14, the controller 8 may execute the processing from S54 onward of the motor burnout prevention processing. In this way, when an abnormality related to the working unit 14 occurs, the controller 8 can notify the user of the abnormality, return the robotic lawnmower 2, 202 to the charging station 110, or have the robotic lawnmower 2, 202 wait in place.

[0108] The first abnormality recovery condition (or the second abnormality recovery condition) may include a situation in which the detection value of the motor current detection circuit 40 (i.e., the current value flowing through the work motor 36) remains below a predetermined current value for a predetermined period of time or more.

[0109] The operating mode of the robotic lawnmower 2, 202 may be changed automatically, regardless of user operation. For example, the control unit 8 may use GPS to identify the work area WA where the robotic lawnmower 2, 202 is mowing, and then change the operating mode of the robotic lawnmower 2, 202 to a mode corresponding to the identified work area WA. Alternatively, the control unit 8 may store map information of the work area WA in advance and identify the work area WA where the robotic lawnmower 2, 202 is mowing based on that map information.

[0110] The detection units 16, 204 may be capable of detecting various abnormalities in addition to the abnormalities described above. For example, the detection units 16, 204 may be capable of detecting that the robot main body 4 has rolled over or that the robot main body 4 has been lifted by someone. When such an abnormality is detected by the detection units 16, 204, the control unit 8 may use a buzzer (not shown) provided in the robot main body 4 to notify the user that an abnormality has occurred.

[0111] Features of Examples 1 and 2 In one or more embodiments, the robotic lawnmower 2, 202 (an example of a working robot) performs work while moving autonomously. The robotic lawnmower 2, 202 includes a working unit 14 including a cutting blade 34 (an example of a working mechanism) that performs work and a work motor 36 that drives the cutting blade 34, a rechargeable battery 18 that supplies power to the work motor 36, a detection unit 16, 204 that detects the state of the working unit 14, and a control unit 8. The control unit 8 is configured to execute an abnormality determination process (see S52 in FIG. 9 ) that determines whether an abnormality has occurred in the working unit 14 based on the detection results of the detection unit 16, 204, and a first abnormality response process (see S56 to S62 in FIG. 9 ) that returns the robotic lawnmower 2, 202 to the charging station 110 with the work motor 36 stopped and begins charging the battery 18. When it is determined in the abnormality determination process that an abnormality has occurred in the working unit 14, the control unit 8 executes a first abnormality response process.

[0112] With the above configuration, if an abnormality occurs in the working unit 14, the robotic lawnmower 2, 202 returns to the charging station 110 and begins charging the battery 18. The battery 18 can be charged during the standby period after the abnormality occurs in the working unit 14. Therefore, after the standby period ends, the robotic lawnmower 2, 202 begins work with the battery 18 having a relatively high remaining charge. This prevents the robotic lawnmower 2, 202 from returning to the charging station 110 too early after the standby period ends. This allows the robotic lawnmower 2, 202 to work smoothly.

[0113] In one or more embodiments, the control unit 8 determines in the abnormality determination process that an abnormality has occurred in the working unit 14 if the working motor 36 overheats.

[0114] If the work motor 36 overheats, it is acceptable to start using the robotic lawnmower 2, 202 as long as the temperature of the work motor 36 subsequently drops. With the above configuration, the battery 18 can be charged during the waiting period after overheating until the temperature of the work motor 36 drops. This allows the robotic lawnmower 2, 202 to start working after the temperature of the work motor 36 has dropped sufficiently, with the battery 18 still having a relatively high remaining charge. This allows the robotic lawnmower 2, 202 to work smoothly.

[0115] In one or more embodiments, the detection unit 16, 204 includes a motor current detection circuit 40 (an example of a current detection unit) that detects the value of a current flowing through the work motor 36. In the abnormality determination process, the control unit 8 determines whether the work motor 36 has overheated based on the detection value of the motor current detection circuit 40.

[0116] According to the above configuration, it is possible to determine whether the work motor 36 has overheated using a simple means.

[0117] In one or more embodiments, the control unit 8 determines that the work motor 36 has overheated during the abnormality determination process if the situation in which the detection value of the motor current detection circuit 40 is a first current value (or a second current value, a third current value) (an example of a predetermined current value) continues for a first duration (or a second duration, a third duration) (an example of a first predetermined time) or longer.

[0118] According to the above configuration, it is possible to determine whether the work motor 36 has overheated using a simple means.

[0119] In one or more embodiments, the control unit 8 starts charging the battery 18 in the first abnormality response process, and then, when the first abnormality recovery condition (an example of a predetermined recovery condition) is met, ends charging the battery 18 and starts work by the robotic lawnmower 2, 202.

[0120] According to the above configuration, after the first abnormality response process has been executed, the robotic lawnmower 2, 202 can automatically start work without a command from the user to start work.

[0121] In one or more embodiments, the control unit 8 determines in the abnormality determination process that an abnormality has occurred in the working unit 14 if the working motor 36 overheats. The first abnormality recovery condition includes the remaining charge of the battery 18 being equal to or greater than a predetermined amount.

[0122] If the battery 18 is being charged due to overheating of the work motor 36, it is preferable that the temperature of the work motor 36 be sufficiently cooled before the robotic lawnmower 2, 202 begins work. For example, if the battery 18 continues to be charged until the remaining charge of the battery 18 reaches a predetermined level or more, it can be assumed that a certain amount of time has passed since the overheating occurred, and that the temperature of the work motor 36 has sufficiently cooled. With the above configuration, the robotic lawnmower 2, 202 begins work after the battery 18 continues to be charged until the remaining charge of the battery 18 reaches a predetermined level or more. Therefore, the robotic lawnmower 2, 202 can begin work after the temperature of the work motor 36 has sufficiently cooled.

[0123] In one or more embodiments, the control unit 8 determines that an abnormality has occurred in the working unit 14 when the work motor 36 overheats in the abnormality determination process. The first abnormality recovery condition includes the time elapsed since the abnormality determination process determined that the work motor 36 has overheated reaching a (second) predetermined time.

[0124] It is considered that the temperature of the work motor 36 has sufficiently dropped after a certain amount of time has passed since overheating occurred. With the above configuration, the robotic lawnmower 2, 202 begins work after a certain amount of time has passed since overheating occurred. Therefore, the robotic lawnmower 2, 202 can start work when the temperature of the work motor 36 has sufficiently dropped.

[0125] In one or more embodiments, the detection unit 204 includes a motor temperature sensor 206 (an example of a temperature sensor) that detects the temperature of the work motor 36. If the work motor 36 overheats during the abnormality determination process, the control unit 8 determines that an abnormality has occurred in the working unit 14. The first abnormality recovery condition includes the temperature of the work motor 36 detected by the motor temperature sensor 206 being equal to or lower than a first predetermined temperature.

[0126] With the above configuration, the robotic lawnmower 2, 202 can start working once the temperature of the work motor 36 has dropped sufficiently.

[0127] In one or more embodiments, the controller 8 is further configured to be able to execute a second anomaly response process (see S64 to S68 in FIG. 9 ) that stops the work motor 36 and causes the robotic lawnmower 2, 202 to wait without returning to the charging station 110. The operating mode of the robotic lawnmower 2, 202 is set to one of a plurality of modes, including a main area response mode (an example of a first mode) in which the controller 8 executes the first anomaly response process if the controller 8 determines in the anomaly determination process that an abnormality has occurred in the working unit 14, and a sub-area response mode (an example of a second mode) in which the controller 8 executes the second anomaly response process if the controller 8 determines in the anomaly determination process that an abnormality has occurred in the working unit 14.

[0128] Some abnormalities related to the working unit 14 require the user to go to the location where the abnormality occurred. When such an abnormality occurs, it is preferable to have the robotic lawnmower 2, 202 wait at the location where the abnormality occurred rather than returning to the charging station 110. Therefore, it is preferable that the response of the robotic lawnmower 2, 202 after an abnormality occurs in the working unit 14 be switchable between returning to the charging station 110 and waiting without returning to the charging station 110. According to the above configuration, the operation modes of the robotic lawnmower 2, 202 include a main area mode in which the robotic lawnmower 2, 202 returns to the charging station 110 after an abnormality occurs in the working unit 14, and a sub-area mode in which the robotic lawnmower 2, 202 waits without returning to the charging station 110 after an abnormality occurs in the working unit 14. Therefore, by changing the operation mode setting, it is possible to switch the response of the robotic lawnmower 2, 202 after an abnormality occurs in the working unit 14 between returning to the charging station 110 and waiting without returning to the charging station 110.

[0129] In one or more embodiments, the operating mode of the robotic lawnmower 2, 202 is user-changeable.

[0130] According to the above configuration, the user can change the operation mode of the robotic lawnmower 2, 202 to change how the robotic lawnmower 2, 202 responds after an abnormality occurs in the working unit 14.

[0131] 12, the work robot of this embodiment is a robotic lawnmower 302 that has substantially the same components as the robotic lawnmower 2 (see FIG. 4) of embodiment 1. Components that are common between the robotic lawnmower 2 and the robotic lawnmower 302 are given the same reference numerals, and their description will be omitted.

[0132] (Heavy Load Avoidance Operation) As shown in FIG. 13 , for example, when the robotic lawnmower 302 enters an area 304 where the grass is overgrown, a heavy load may be placed on the work motor 36 (see FIG. 12 ) as the lawn is mowed. The control unit 8 of the robotic lawnmower 302 of this embodiment can determine whether a heavy load has been placed on the work motor 36 based on the value detected by the motor current detection circuit 40. For example, the control unit 8 determines that a heavy load has been placed on the work motor 36 if the value detected by the motor current detection circuit 40 (i.e., the current flowing through the work motor 36) remains at or above a fourth current value (e.g., 6 A) for a fourth duration (e.g., 1 second) or longer. If the control unit 8 determines that a heavy load has been placed on the work motor 36, it causes the robotic lawnmower 302 to perform a predetermined heavy load avoidance operation. In the example of Figure 13, the heavy load avoidance operation is an operation in which the robot moves in the opposite direction to the direction of travel just before a heavy load is applied to the work motor 36, and then starts moving in a direction that is changed by 90 degrees from that direction.

[0133] (Overheat Determination Process Using Counter C) As shown in FIG. 12, the memory 24 of the control unit 8 stores a counter C and a current-counter table T. The counter C is used as an index that alternatively represents the temperature of the work motor 36. As shown in FIG. 14, the current-counter table T describes a plurality of conditions related to the detected value of the motor current detection circuit 40 (i.e., the value of the current flowing through the work motor 36) and the fluctuation ΔC of the counter C corresponding to each condition. In the example of FIG. 14, the following conditions are listed: condition a (the detected value of the motor current detection circuit 40 is less than 2 A), the fluctuation ΔC (=-40) corresponding to condition a), condition b (the detected value of the motor current detection circuit 40 is 2 A or more and less than 4 A), the fluctuation ΔC (=0) corresponding to condition b), condition c (the detected value of the motor current detection circuit 40 is 4 A or more and less than 5 A), the fluctuation ΔC (=50) corresponding to condition c), and condition d (the detected value of the motor current detection circuit 40 is 5 A or more and less than 6 A). The table 24 describes the following: condition d (the detected value of the motor current detection circuit 40 is equal to or greater than 6 A and less than 7 A), a fluctuation ΔC (=100) corresponding to condition d; condition e (the detected value of the motor current detection circuit 40 is equal to or greater than 6 A and less than 7 A), a fluctuation ΔC (=200) corresponding to condition e; condition f (the detected value of the motor current detection circuit 40 is equal to or greater than 7 A and less than 8 A), a fluctuation ΔC (=400) corresponding to condition f; condition g (the detected value of the motor current detection circuit 40 is equal to or greater than 8 A), and a fluctuation ΔC (=800) corresponding to condition g. The control unit 8 periodically updates the counter C stored in the memory 24 (e.g., every second). At this time, the control unit 8 acquires the detected value of the motor current detection circuit 40, determines the fluctuation ΔC based on the acquired detected value of the motor current detection circuit 40 and the current-counter table T, and fluctuates the counter C by the determined fluctuation ΔC. For example, if the value detected by the motor current detection circuit 40 is 1 A, condition a (the value detected by the motor current detection circuit 40 is less than 2 A) is met, and the control unit 8 fluctuates the counter C by the fluctuation ΔC (=-40) corresponding to condition a. The fluctuation ΔC of the counter C can also be considered an index representing the rate of change in the temperature of the work motor 36. In this embodiment, the greater the detected value of the motor current detection circuit 40, the greater the value of the fluctuation ΔC of the counter C is set to (see FIG. 14).This is in accordance with the fact that the greater the current value flowing through the work motor 36, the greater the rate at which the temperature of the work motor 36 changes.

[0134] As shown in FIG. 15 , when the robotic lawnmower 302 begins mowing, the work motor 36 (see FIG. 12 ) operates (i.e., current flows through the work motor 36), causing the value of counter C to fluctuate from its initial value (0 in this embodiment). For example, when the robotic lawnmower 302 moves over overgrown grass (i.e., grass that has not been recently mowed), the load on the work motor 36, and therefore the current flowing through the work motor 36, becomes relatively large, causing the value of counter C to increase. On the other hand, when the robotic lawnmower 302 moves over sparse grass (i.e., grass that has been recently mowed), the load on the work motor 36, and therefore the current flowing through the work motor 36, becomes relatively small, causing the value of counter C to decrease. For example, after performing heavy load avoidance operation (see FIG. 13 ), the robotic lawnmower 302 may move over sparse grass (i.e., grass that has been recently mowed), causing the value of counter C to decrease.

[0135] Like the control unit 8 of the first embodiment, the control unit 8 of this embodiment repeatedly executes the motor burnout prevention process shown in FIG. 9 during lawnmowing operation. In S52 of the motor burnout prevention process, the control unit 8 of this embodiment determines whether the work motor 36 (see FIG. 12 ) has overheated based on the value of counter C. Specifically, the control unit 8 determines that the work motor 36 has overheated (YES) when the value of counter C is equal to or greater than a predetermined first determination threshold (see FIG. 15 ). The control unit 8 determines that the work motor 36 has not overheated (NO) when the value of counter C is less than the first determination threshold. This is because it can be inferred that the temperature of the work motor 36 is high when the value of counter C is large, and that the temperature of the work motor 36 is low when the value of counter C is small.

[0136] When the robotic lawnmower 302 is mowing in the main area MA (see FIG. 1 ) and the value of counter C is equal to or greater than the first threshold (YES in S52 and YES in S54), the robotic lawnmower 302 stops mowing and begins returning to the charging station 110 (S56). The robotic lawnmower 302 then begins charging the battery 18 (S58). As shown in FIG. 15 , while the robotic lawnmower 302 is returning to the charging station 110 and charging the battery 18, the work motor 36 is stopped (i.e., no current flows through the work motor 36), and the value of counter C gradually decreases. This corresponds to a gradual decrease in the temperature of the work motor 36.

[0137] In this embodiment, after determining that the work motor 36 has overheated (YES in S52), the control unit 8 determines whether the overheating of the work motor 36 has been resolved based on the value of counter C. Specifically, the control unit 8 determines that the overheating of the work motor 36 has been resolved when the value of counter C is below a second determination threshold (see FIG. 15 ), which is a value smaller than the first determination threshold. The control unit 8 determines that the overheating of the work motor 36 has not been resolved when the value of counter C is equal to or greater than the second determination threshold. Furthermore, in S60 of the motor burnout prevention process shown in FIG. 9 , the control unit 8 sets the elimination of the overheating of the work motor 36 (i.e., the value of counter C being below the second determination threshold) as the first abnormality recovery condition. Therefore, if the value of counter C falls below the second threshold, the first abnormality recovery condition is met (YES in S60), and the robotic lawnmower 302 stops charging the battery 18 and resumes mowing (S62). Also, in S66 of the motor burnout prevention process shown in Figure 9, the control unit 8 may set the second abnormality recovery condition to be that the overheating of the work motor 36 has been resolved (i.e., the value of counter C falls below the second threshold).

[0138] As shown in FIG. 15 , the value of counter C remains unchanged even after mowing resumes, fluctuating depending on the current flowing through the work motor 36. Alternatively, it is conceivable to configure counter C to be initialized (i.e., reset to zero) when mowing resumes. However, in this configuration, the value of counter C fluctuates discretely when mowing resumes, which could result in a discrepancy between the value of counter C after mowing resumes and the temperature of the work motor 36. This is because the temperature of the work motor 36 does not fluctuate discretely. As a result, the control unit 8 may not be able to accurately determine whether the work motor 36 has overheated. In this embodiment, the value of counter C remains unchanged even after mowing resumes, preventing a discrepancy between the value of counter C after mowing resumes and the temperature of the work motor 36. This allows the control unit 8 to accurately determine whether the work motor 36 has overheated, even after mowing resumes.

[0139] Example 4 The working robot of this example is the robotic lawnmower 302 of Example 3, with some modifications made to the processing executed by the controller 8. The modified processing will be described below.

[0140] As shown in FIG. 16 , when lawnmowing operation resumes, the control unit 8 initializes (i.e., resets) the value of counter C and changes the first determination threshold to a smaller value. As described in the third embodiment, initializing (i.e., resetting) the value of counter C may prevent the control unit 8 from accurately determining whether the work motor 36 has overheated. Specifically, even if the work motor 36 has overheated, the value of counter C may never reach or exceed the first determination threshold, leading to the control unit 8 continuing to determine that the work motor 36 has not overheated. However, in this embodiment, when the value of counter C is initialized, the first determination threshold is changed to a smaller value. In other words, the first determination threshold is reduced by the amount of reduction in counter C resulting from the initialization of counter C. Therefore, even if counter C is initialized (i.e., resets to zero), if a large current flows through the work motor 36, the value of counter C may reach the first determination threshold relatively quickly. This prevents the value of counter C from never reaching or exceeding the first determination threshold when the work motor 36 is overheating, and prevents the work motor 36 from continuing to be determined not to be overheating. As a result, the control unit 8 can accurately determine whether the work motor 36 has overheated even after lawn mowing work has resumed.

[0141] The control unit 8 may be configured to suspend mowing, start charging the battery 18, and then resume mowing if the voltage of the battery 18 detected by the battery voltage detection circuit 42 (see FIG. 12 ) reaches a predetermined value (e.g., 20 V) or higher. In this configuration, the control unit 8 may set the first determination threshold for when mowing resumes based on the voltage of the battery 18 at the start of charging. For example, the control unit 8 may set the first determination threshold for when mowing resumes to a lower value the higher the voltage of the battery 18 at the start of charging. This is because the higher the voltage of the battery 18 at the start of charging, the shorter the time until charging of the battery 18 is completed (i.e., when mowing resumes) and the higher the temperature of the work motor 36 is (i.e., when the value of counter C is large), and therefore the counter C is expected to decrement significantly when counter C is initialized.

[0142] Fifth Embodiment The working robot of this embodiment is the robotic lawnmower 302 of the third embodiment, with some modifications made to the processing executed by the controller 8. The modified processing will be described below.

[0143] As shown in FIG. 17 , the control unit 8 initializes (i.e., resets) the value of counter C when lawnmowing operation is resumed. As described in the third embodiment, initializing (i.e., resetting) the value of counter C may prevent the control unit 8 from accurately determining whether the work motor 36 has overheated. Specifically, even if the work motor 36 has overheated, the value of counter C may never reach or exceed the first determination threshold, and the control unit 8 may continue to determine that the work motor 36 has not overheated. However, after lawnmowing operation is resumed, the control unit 8 of this embodiment updates counter C based on current-counter table T′ shown in FIG. 18 instead of current-counter table T shown in FIG. 14 . Compared to current-counter table T, current-counter table T′ has a larger value for the fluctuation ΔC (also referred to as the “increment”) when increasing counter C. Specifically, the current-counter table T' is calculated by multiplying the fluctuation ΔC corresponding to condition c, the fluctuation ΔC corresponding to condition d, the fluctuation ΔC corresponding to condition e, the fluctuation ΔC corresponding to condition f, and the fluctuation ΔC corresponding to condition g in the current-counter table T by 1.5. Therefore, after the lawnmowing operation is resumed, the increment of counter C is increased to a larger value, taking into account the decrement of counter C due to the initialization of counter C. Therefore, even if counter C is initialized (i.e., reset to zero), the value of counter C increases relatively significantly when a large current flows through the work motor 36. This prevents the counter C value from never reaching or exceeding the first determination threshold when the work motor 36 is overheating, thereby preventing the control unit 8 from continuing to determine that the work motor 36 is not overheating. As a result, the control unit 8 can accurately determine whether the work motor 36 has overheated even after the lawnmowing operation is resumed.

[0144] The control unit 8 may be configured to suspend lawn mowing, start charging the battery 18, and then resume lawn mowing if the voltage of the battery 18 detected by the battery voltage detection circuit 42 (see FIG. 12) reaches a predetermined value (e.g., 20 V) or higher. In this configuration, the control unit 8 may determine the value of the fluctuation ΔC to be recorded in the current-counter table T' based on the voltage of the battery 18 at the start of charging. For example, the control unit 8 may determine a larger increment of the counter C to be recorded in the current-counter table T' the greater the voltage of the battery 18 at the start of charging. This is because the greater the voltage of the battery 18 at the start of charging, the shorter the time until charging of the battery 18 is completed (i.e., lawn mowing resumes), and the higher the temperature of the work motor 36 is when lawn mowing resumes (i.e., the greater the value of counter C), and therefore the greater the decrement of counter C that is expected to occur when counter C is initialized.

[0145] (Modifications of Examples 3, 4, and 5) The work robot in Examples 3, 4, and 5 may be a robot other than the robotic lawnmower 302. For example, the work robot may be a robot vacuum cleaner equipped with a brush and / or a suction mechanism for collecting dust and other debris. In this case, the work motor 36 may be used as a motor for driving the brush and / or the suction mechanism. The work robot may also be a rebar binding robot equipped with a rebar binding mechanism for binding together the intersections of multiple rebars. In this case, the work motor 36 may be used as a motor for driving the rebar binding mechanism.

[0146] The operating mode of the robotic lawnmower 302 in Examples 3, 4, and 5 may be changed automatically, regardless of user operation. For example, the control unit 8 may use GPS to identify the work area WA where the robotic lawnmower 302 is mowing, and then change the operating mode of the robotic lawnmower 302 to a mode corresponding to the identified work area WA. Alternatively, the control unit 8 may store map information of the work area WA in advance and identify the work area WA where the robotic lawnmower 302 is mowing based on that map information.

[0147] In the motor burnout prevention process shown in Figure 9, after starting charging of the battery 18 in S58, the control unit 8 in Examples 3, 4, and 5 may end the motor burnout prevention process and terminate the ongoing lawnmowing operation instead of executing the processes from S60 onwards. Thereafter, the control unit 8 may stop charging the battery 18 when the battery 18 is fully charged, for example, and place the robotic lawnmower 302 on standby at the charging station 110. In other words, the control unit 8 may be configured not to automatically resume lawnmowing after an abnormality occurs in the robotic lawnmower 302 (overheating of the work motor 36).

[0148] The control unit 8 in Examples 3, 4, and 5 may be configured to vary counter C based on a detection value other than the detection value of the motor current detection circuit 40 (i.e., the value of the current flowing through the work motor 36). For example, the control unit 8 may be configured to vary counter C based on the detection value of a rotational speed detection sensor (not shown) that detects the rotational speed of the work motor 36. In this example, the control unit 8 may increment counter C when the rotational speed of the work motor 36 is high (i.e., when it is estimated that the temperature of the work motor 36 is rising), and decrement counter C when the rotational speed of the work motor 36 is low (i.e., when it is estimated that the temperature of the work motor 36 is falling).

[0149] The control unit 8 in Examples 3, 4, and 5 may decrease the counter C when the value of the current flowing through the work motor 36 is large (i.e., when it is estimated that the temperature of the work motor 36 is rising), and may increase the counter C when the value of the current flowing through the work motor 36 is small (i.e., when it is estimated that the temperature of the work motor 36 is falling). In this example, the control unit 8 may determine that the work motor 36 has overheated when the value of the counter C falls below a predetermined threshold.

[0150] The control unit 8 in Examples 3, 4, and 5 does not need to determine whether the overheating of the work motor 36 has been resolved (i.e., whether the value of counter C has fallen below the second determination threshold). In this example, the first abnormality recovery condition used in S60 of the motor burnout prevention processing does not need to include the elimination of the overheating of the work motor 36 (i.e., the value of counter C falling below the second determination threshold). The second abnormality recovery condition used in S66 of the motor burnout prevention processing does not need to include the elimination of the overheating of the work motor 36 (i.e., the value of counter C falling below the second determination threshold).

[0151] In the fifth embodiment, after mowing resumes, the control unit 8 may reduce the absolute value of the variation ΔC (also referred to as the "decrease") when decrementing the counter C compared to before mowing resumed. Specifically, after mowing resumes, the control unit 8 may change the variation ΔC corresponding to condition a to a smaller absolute value (for example, -20) compared to the value before mowing resumed (-40).

[0152] The control unit 8 in Examples 3, 4, and 5 may be configured to change the traveling speed of the robotic lawnmower 302 (i.e., the rotational speed of the travel motors 32L, 32R) based on the detection value of the motor current detection circuit 40 (i.e., the current value flowing through the work motor 36). For example, the control unit 8 may be configured to execute a first travel control to set the traveling speed of the robotic lawnmower 302 to 2.0 km / h when the detection value of the motor current detection circuit 40 is less than 6 A, and to execute a second travel control to set the traveling speed of the robotic lawnmower 302 to 1.0 km / h when the detection value of the motor current detection circuit 40 is 6 A or greater. In this example, the control unit 8 may control the traveling speed of the robotic lawnmower 302 based on a sensor (not shown) that detects the rotational speed of the travel motors 32L, 32R, or may control the traveling speed of the robotic lawnmower 302 based on a sensor (not shown) that detects the rotational speed of the drive wheels 30L, 30R. Furthermore, when the second travel control is continuously executed for one second or more, the control unit 8 may cause the robotic lawnmower 302 to execute a heavy load avoidance operation (see FIG. 13).

[0153] In the fourth and fifth embodiments, when mowing resumes, instead of resetting the value of counter C to zero, the control unit 8 may reset the value of counter C to a reset value other than zero. This reset value may be a fixed value. Alternatively, the reset value may be a value calculated by the control unit 8 based on the results of previous mowing operations (for example, the value of counter C when mowing was interrupted, or the value detected by the motor current detection circuit 40 when mowing was interrupted).

[0154] In the fourth and fifth embodiments, the control unit 8 may reset the value of the counter C at any timing after interrupting the lawn mowing operation. For example, the control unit 8 may reset the value of the counter C immediately after interrupting the lawn mowing operation.

[0155] (Features of Examples 3, 4, and 5) In one or more embodiments, a robotic lawnmower 302 (an example of a working robot) performs work while autonomously moving. The robotic lawnmower 302 includes a working unit 14 including a cutting blade 34 (an example of a working mechanism) that performs work and a work motor 36 that drives the cutting blade 34, a rechargeable battery 18 that supplies power to the work motor 36, a detection unit 16 that detects the state of the working unit 14, and a control unit 8. The control unit 8 is configured to execute an abnormality determination process (see S52 in FIG. 9 ) that determines whether an abnormality has occurred in the working unit 14 based on the detection results of the detection unit 16, and a first abnormality response process (see S56 to S62 in FIG. 9 ) that returns the robotic lawnmower 302 to the charging station 110 with the work motor 36 stopped and begins charging the battery 18. The control unit 8 executes the first abnormality response process when the abnormality determination process determines that an abnormality has occurred in the working unit 14.

[0156] With the above configuration, if an abnormality occurs in the working unit 14, the robotic lawnmower 302 returns to the charging station 110 and begins charging the battery 18. The battery 18 can be charged during the standby period after the abnormality occurs in the working unit 14. Therefore, after the standby period ends, the robotic lawnmower 302 begins work with the battery 18 having a relatively high remaining charge. This prevents the robotic lawnmower 302 from returning to the charging station 110 too early after the standby period ends. This allows the robotic lawnmower 302 to work smoothly.

[0157] In one or more embodiments, the control unit 8 determines in the abnormality determination process that an abnormality has occurred in the working unit 14 if the working motor 36 overheats.

[0158] If the work motor 36 overheats, it is okay to start using the robotic lawnmower 302 as long as the temperature of the work motor 36 subsequently drops. With the above configuration, the battery 18 can be charged during the waiting period until the temperature of the work motor 36 drops after overheating. Therefore, once the temperature of the work motor 36 has dropped sufficiently, the robotic lawnmower 302 can start working with a relatively high remaining charge in the battery 18. This allows the robotic lawnmower 302 to work smoothly.

[0159] In one or more embodiments, the detection unit 16 includes a motor current detection circuit 40 (an example of a current detection unit) that detects the value of a current flowing through the work motor 36. In the abnormality determination process, the control unit 8 determines whether the work motor 36 has overheated based on the detection value of the motor current detection circuit 40.

[0160] According to the above configuration, it is possible to determine whether the work motor 36 has overheated using a simple means.

[0161] In one or more embodiments, the control unit 8 starts charging the battery 18 in the first abnormality response process, and then, when the first abnormality recovery condition (an example of a predetermined recovery condition) is met, ends charging the battery 18 and starts work by the robotic lawnmower 302.

[0162] According to the above configuration, after the first abnormality response process has been executed, the robotic lawnmower 302 can automatically start work without a command from the user to start work.

[0163] In one or more embodiments, the control unit 8 determines in the abnormality determination process that an abnormality has occurred in the working unit 14 if the working motor 36 overheats. The first abnormality recovery condition includes the remaining charge of the battery 18 being equal to or greater than a predetermined amount.

[0164] If the battery 18 is being charged due to overheating of the work motor 36, it is preferable that the temperature of the work motor 36 be sufficiently cooled before the robotic lawnmower 302 begins work. For example, if the battery 18 continues to be charged until the remaining charge of the battery 18 reaches a predetermined level or more, it can be assumed that a certain amount of time has passed since the overheating occurred, and that the temperature of the work motor 36 has sufficiently cooled. With the above configuration, the robotic lawnmower 302 begins work after the battery 18 continues to be charged until the remaining charge of the battery 18 reaches a predetermined level or more. Therefore, the robotic lawnmower 302 can begin work after the temperature of the work motor 36 has sufficiently cooled.

[0165] In one or more embodiments, the control unit 8 determines that an abnormality has occurred in the working unit 14 when the work motor 36 overheats in the abnormality determination process. The first abnormality recovery condition includes a predetermined time having elapsed since the abnormality determination process determined that the work motor 36 overheated.

[0166] It is considered that the temperature of the work motor 36 has sufficiently dropped after a certain amount of time has passed since overheating occurred. With the above configuration, the robotic lawnmower 302 begins work after a certain amount of time has passed since overheating occurred. Therefore, the robotic lawnmower 302 can start work after the temperature of the work motor 36 has sufficiently dropped.

[0167] In one or more embodiments, the controller 8 is further configured to be able to execute a second anomaly response process (see S64 to S68 in FIG. 9 ) that stops the work motor 36 and causes the robotic lawnmower 302 to wait without returning to the charging station 110. The operating mode of the robotic lawnmower 302 is set to one of a plurality of modes, including a main area response mode (an example of a first mode) in which the controller 8 executes the first anomaly response process if the controller 8 determines in the anomaly determination process that an abnormality has occurred in the working unit 14, and a sub-area response mode (an example of a second mode) in which the controller 8 executes the second anomaly response process if the controller 8 determines in the anomaly determination process that an abnormality has occurred in the working unit 14.

[0168] Some abnormalities related to the working unit 14 require the user to go to the location where the abnormality occurred. When such an abnormality occurs, it is preferable to have the robotic lawnmower 302 wait at the location where the abnormality occurred rather than returning to the charging station 110. Therefore, it is preferable that the response of the robotic lawnmower 302 after an abnormality occurs in the working unit 14 be switchable between returning to the charging station 110 and waiting without returning to the charging station 110. According to the above configuration, the operation modes of the robotic lawnmower 302 include a main area mode in which the robotic lawnmower 302 returns to the charging station 110 after an abnormality occurs in the working unit 14, and a sub-area mode in which the robotic lawnmower 302 waits without returning to the charging station 110 after an abnormality occurs in the working unit 14. Therefore, by changing the operation mode setting, it is possible to switch the response of the robotic lawnmower 302 after an abnormality occurs in the working unit 14 between returning to the charging station 110 and waiting without returning to the charging station 110.

[0169] In one or more embodiments, the operating mode of the robotic lawnmower 302 is user-changeable.

[0170] According to the above configuration, the user can change the operation mode of the robotic lawnmower 302 to change how the robotic lawnmower 302 responds after an abnormality occurs in the working unit 14 .

[0171] In one or more embodiments, the control unit 8 includes a counter C. When a first counter variation condition (e.g., condition a) based on the detection result of the detection unit 16 is met, the control unit 8 varies the value of the counter C by a first variation amount ΔC (=−40). When a second counter variation condition (e.g., condition c) based on the detection result of the detection unit 16 is met, the control unit 8 varies the value of the counter C by a second variation amount ΔC (=50). Based on the value of the counter C, the control unit 8 determines whether the work motor 36 has overheated.

[0172] With the above configuration, the control unit 8 can determine whether the work motor 36 has overheated based on an index (the value of counter C) that depends on multiple conditions a, b, c, d, e, f, and g. For example, counter C can be used as an index representing the temperature of the work motor 36. In this case, the control unit 8 can increase the value of counter C when conditions c, d, e, f, and g that induce an increase in the temperature of the work motor 36 are met, and decrease the value of counter C when condition a that induces a decrease in the temperature of the work motor 36 is met. The control unit 8 can then determine that the work motor 36 has overheated when the value of counter C increases. In this way, the control unit 8 can comprehensively consider multiple conditions a, b, c, d, e, f, and g when determining whether the work motor 36 has overheated. This allows the control unit 8 to accurately determine whether the work motor 36 has overheated.

[0173] In one or more embodiments, the detection unit 16 includes a motor current detection circuit 40 that detects the value of a current flowing through the work motor 36. A first counter fluctuation condition (e.g., condition a) is that the detected value of the motor current detection circuit 40 is in a first numerical range (less than 2 A). A second counter fluctuation condition (e.g., condition c) is that the detected value of the motor current detection circuit 40 is in a second numerical range (greater than 4 A and less than 5 A).

[0174] With the above configuration, the control unit 8 can accurately determine whether the work motor 36 has overheated by comprehensively considering multiple conditions a, b, c, d, e, f, and g related to the value of the current flowing through the work motor 36. For example, if counter C is used as an index representing the temperature of the work motor 36, the control unit 8 can increase or decrease the value of counter C depending on the value of the current flowing through the work motor 36. Then, when the value of counter C increases, the control unit 8 can determine that the work motor 36 has overheated.

[0175] In one or more embodiments, one of the first fluctuation amount ΔC (=-40) and the second fluctuation amount ΔC (=50) is a positive value. The other of the first fluctuation amount ΔC (=-40) and the second fluctuation amount ΔC (=50) is a negative value. The control unit 8 determines that the work motor 36 has overheated when the value of the counter C is equal to or greater than a predetermined first determination threshold.

[0176] According to the above configuration, the control unit 8 determines that the work motor 36 has overheated when the value of the counter C increases. As a result, for example, by using the counter C as an index representing the temperature of the work motor 36, it is possible to determine that the work motor 36 has overheated when the value of the counter C (the temperature of the work motor 36) increases.

[0177] In one or more embodiments, after determining that the work motor 36 has overheated, the control unit 8 determines that the overheating of the work motor 36 has been resolved if the value of the counter C falls below a predetermined second determination threshold.

[0178] With the above configuration, the control unit 8 determines that the overheating of the work motor 36 has been resolved if the value of the counter C decreases after determining that the work motor 36 has overheated. As a result, for example, by using the counter C as an index representing the temperature of the work motor 36, it can be determined that the overheating of the work motor 36 has been resolved if the value of the counter C (the temperature of the work motor 36) decreases.

[0179] In one or more embodiments, after the controller 8 starts charging the battery 18 in the first abnormality response process, if a first abnormality recovery condition is met, the controller 8 stops charging the battery 18 and starts work by the robotic lawnmower 302. The first abnormality recovery condition includes the controller 8 determining that the overheating of the work motor 36 has been resolved.

[0180] With the above configuration, the robotic lawnmower 302 can automatically resume work that was interrupted due to the overheating of the work motor 36.

[0181] In one or more embodiments, the control unit 8 starts charging the battery 18 in the first anomaly response process, and then, when the first anomaly recovery condition is met, stops charging the battery 18 and starts work with the robotic lawnmower 302. The control unit 8 does not initialize the value of the counter C during the work interruption period associated with charging the battery 18.

[0182] It is also conceivable to configure the counter C to be initialized (e.g., reset to zero) during a work interruption. However, there are cases where it is desirable to refer to the value of counter C before work was interrupted during the work interruption and / or after work is resumed. For example, there are cases where it is desirable to determine whether the overheating of the work motor 36 has been resolved based on the value of counter C before work was interrupted. With the above configuration, since the value of counter C is not initialized during a work interruption, it is possible to refer to the value of counter C before work was interrupted during the work interruption and / or after work is resumed.

Claims

1. A working robot that performs work while moving autonomously, comprising: a working unit including a working mechanism that performs work and a work motor that drives the working mechanism; a rechargeable battery that supplies power to the work motor; a detection unit that detects the state of the working unit; and a control unit, wherein the control unit is configured to execute an abnormality determination process that determines whether or not an abnormality has occurred in the working unit based on the detection result by the detection unit; and a first abnormality response process that returns the work robot to a charging station with the work motor stopped and begins charging the battery, and the control unit executes the first abnormality response process when it is determined in the abnormality determination process that an abnormality has occurred in the working unit.

2. The working robot of claim 1, wherein the control unit determines in the abnormality determination process that an abnormality has occurred in the working unit if the working motor has overheated.

3. A work robot as claimed in claim 2, wherein the detection unit includes a current detection unit which detects the value of a current flowing through the work motor, and the control unit, in the abnormality determination process, determines whether or not the work motor has overheated based on the detection value of the current detection unit.

4. A work robot as claimed in claim 3, wherein the control unit determines that the work motor has overheated if, during the abnormality determination process, the detection value of the current detection unit remains equal to or above a predetermined current value for a first predetermined time or longer.

5. A work robot according to any one of claims 1 to 4, wherein the control unit, after starting charging of the battery in the first anomaly response process, terminates charging of the battery and starts work by the work robot when a predetermined recovery condition is met.

6. A working robot as claimed in claim 5, wherein the control unit determines in the abnormality determination process that an abnormality has occurred in the working unit if the working motor overheats, and the recovery condition includes the remaining charge of the battery being equal to or greater than a predetermined amount.

7. A work robot according to claim 5 or 6, wherein the control unit determines that an abnormality has occurred in the working unit if the work motor overheats in the abnormality determination process, and the recovery condition includes the elapsed time from when it is determined in the abnormality determination process that the work motor has overheated reaching a second predetermined time.

8. A work robot according to any one of claims 5 to 7, wherein the detection unit includes a temperature sensor that detects the temperature of the work motor, and the control unit determines in the abnormality determination process that an abnormality has occurred in the work unit if the work motor overheats, and the recovery condition includes that the temperature of the work motor detected by the temperature sensor is equal to or lower than a first predetermined temperature.

9. A work robot according to any one of claims 1 to 8, wherein the control unit is further configured to be capable of executing a second abnormality response process in which the work robot waits without returning to the charging station with the work motor stopped, and the operation mode of the work robot is set to any one of a plurality of modes including a first mode in which the control unit executes the first abnormality response process when it is determined in the abnormality determination process that an abnormality has occurred in the working unit, and a second mode in which the control unit executes the second abnormality response process when it is determined in the abnormality determination process that an abnormality has occurred in the working unit.

10. The work robot of claim 9, wherein the operational mode of the work robot is changeable by a user.

11. The work robot of claim 2, wherein the control unit is equipped with a counter, and when a first counter fluctuation condition based on the detection result of the detection unit is satisfied, the control unit fluctuates the value of the counter by a first fluctuation amount, and when a second counter fluctuation condition based on the detection result of the detection unit is satisfied, the control unit fluctuates the value of the counter by a second fluctuation amount, and the control unit determines whether the work motor has overheated based on the value of the counter.

12. A work robot as claimed in claim 11, wherein the detection unit includes a current detection unit which detects the value of a current flowing through the work motor, the first counter fluctuation condition being that the detection value of the current detection unit is within a first numerical range, and the second counter fluctuation condition being that the detection value of the current detection unit is within a second numerical range.

13. A work robot according to claim 11 or 12, wherein one of the first fluctuation and the second fluctuation is a positive value, and the other of the first fluctuation and the second fluctuation is a negative value, and the control unit determines that the work motor has overheated when the value of the counter is equal to or greater than a predetermined first judgment threshold.

14. A work robot according to claim 13, wherein the control unit determines that the overheating of the work motor has been resolved if the value of the counter falls below a predetermined second determination threshold after determining that the work motor has overheated.

15. A work robot as claimed in claim 14, wherein the control unit, after starting charging of the battery in the first anomaly response process, when a predetermined recovery condition is met, terminates charging of the battery and starts work by the work robot, and the recovery condition includes the control unit determining that overheating of the work motor has been resolved.

16. A work robot according to any one of claims 11 to 15, wherein after the control unit starts charging the battery in the first anomaly response process, when a predetermined recovery condition is satisfied, the control unit terminates charging of the battery and starts work by the work robot, and the control unit does not initialize the value of the counter during a work interruption period associated with charging the battery.

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