JP2000029520A - Method and vehicle for autonomous travel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of operation accompanying an autonomous travel by allowing a travel vehicle to start traveling autonomously when a state wherein position measurement is normal recovers in a specific period after the autonomous travel is quitted. SOLUTION: A flag GPS is 0 (S501). A position measurement information check part judges whether or not a recovery from an occurring position measurement abnormality has been made (S504). If the position measurement abnormality has been recovered, the flag GPS is changed from 0 to 1. An abnormality processing mode is quitted and an autonomous travel mode is restarted (S505). If the occurring position measurement abnormality has not been recovered, it is judged whether the elapsed time from the occurrence of the position measurement abnormality exceeds a limit time. When not, an advance to (Return) is made and this flow is executed again (S506). When the elapsed time exceeds the limit time, a flag STOP is changed from 0 to 1 (S507). Consequently, the abnormality processing mode for recovering from the position measurement abnormality is quitted and the engine of a working vehicle is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous vehicle that travels while confirming its own position based on positioning information from a captured satellite, and more particularly, to traveling control when an abnormality occurs in the positioning. About.

[0002]

2. Description of the Related Art Autonomous vehicles that perform programmed work unmannedly using autonomous traveling technology are being put to practical use in various fields. Typical examples of the work that can be performed by such an autonomous vehicle include lawn mowing and mowing in various fields such as a golf course, a ground, and a park, plowing of fields, spraying of pesticides and fertilizers, and civil engineering work. .

[0003] This autonomous driving is performed by a global positioning system (Glo
bal Positioning System. This is performed by using two technologies called GPS and dead reckoning in combination. GP
S is a technology for receiving a radio wave emitted from a GPS satellite that is being captured and measuring its own position. Dead-reckoning navigation is a technique for driving a traveling vehicle toward a target point based on the traveling direction of the traveling vehicle measured by a geomagnetic direction sensor or the like and the traveling distance measured by a wheel encoder or the like. The target point (absolute position) of the autonomous vehicle is measured by GPS positioning based on the captured satellite, and by dead reckoning navigation,
The relative position based on the target point is measured.

[0004] However, during autonomous traveling, a situation may occur in which GPS positioning becomes abnormal. There are various factors that cause an abnormality in the GPS positioning, and the most typical factor is radio interference including multipath. Reflection of radio waves on buildings, trees, and the like may cause a multipath, and the radio waves may reach the autonomous vehicle via a plurality of routes. Such a multipath interferes with a direct wave and causes a reception failure. In addition, even when the radio waves from the captured satellite are blocked by buildings and trees around the autonomous vehicle, the autonomous vehicle cannot perform this positioning. Furthermore, G
Positioning becomes impossible even when a failure of the system itself such as a failure of the PS antenna or a failure of the GPS receiving unit occurs.

In the prior art, when such an abnormality occurs in the positioning by the GPS during the execution of the unmanned operation by the autonomous traveling, the traveling or the engine is immediately stopped without any recovery processing. Is going. Then, when such a stop occurs, a measure is taken such that the work manager goes to the stop place, performs the work necessary to restore the normal state, and then resumes the autonomous traveling. However, from the viewpoint of the cost required for the work, it is preferable that the work be continued as much as possible, and the conventional method is a major factor in increasing the work cost.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a control system capable of automatically restarting autonomous traveling even when an abnormality occurs in positioning, thereby improving the operation. Is to reduce the possibility of being stopped, and to improve work efficiency.

[0007]

SUMMARY OF THE INVENTION In view of the above objects, a first aspect of the present invention is to measure the current position of a traveling vehicle by receiving radio waves emitted from a satellite, and based on the positioning. In the autonomous driving method for performing autonomous driving, when it is determined that the positioning is not normal, a step of stopping the autonomous driving of the traveling vehicle, a step of determining whether or not the positioning has recovered to a normal state, If the positioning is restored to the normal state before the specified period elapses from the cancellation,
Restarting autonomous traveling of the traveling vehicle.

[0008] Here, when a radio wave emitted from a satellite cannot be received, when information on positioning is not obtained, information on positioning is obtained, but an error of information on positioning is detected, or If at least one of the cases where the number of satellites required for positioning cannot be acquired, it may be determined that positioning is not normal.

Further, following the step of stopping the autonomous traveling, a step of stopping the traveling vehicle for a predetermined period may be further provided.

It is preferable that the step of determining whether or not the positioning has returned to a normal state is performed during the execution of an abnormality processing mode for setting the traveling vehicle to a predetermined traveling state.

The abnormality processing mode includes, for example, moving a traveling vehicle forward in a programmed direction, or moving the traveling vehicle backward based on a traveling history.
Preferably, the traveling vehicle travels in a pre-programmed direction.

[0012] Further, a step of stopping the operation of the drive source for driving the traveling vehicle when the positioning does not recover to a normal state before the predetermined period elapses from the suspension of the autonomous traveling is further provided. Is also good.

According to a second aspect of the present invention, an autonomous vehicle that measures the current position of the traveling vehicle by receiving radio waves emitted from the satellite and performs autonomous traveling based on the positioning is transmitted from the satellite. By receiving the received radio wave,
Autonomous traveling based on the position detecting means for measuring the current position of the autonomous vehicle, the judging means for judging whether or not the positioning is normal, the output from the position detecting means, and the output from the position detecting means. Control means for controlling the traveling of the vehicle, wherein the control means stops the autonomous traveling of the autonomous traveling vehicle when the positioning is determined to be abnormal, and a predetermined period elapses from the suspension of the autonomous traveling. In the meantime, the present invention provides an autonomous traveling vehicle having a control unit that restarts autonomous traveling of the autonomous traveling vehicle when positioning returns to a normal state.

[0014] The determination means determines whether or not the radio wave emitted from the satellite could not be received, the information on the positioning could not be obtained, or the information on the positioning could be obtained. Alternatively, it is preferable to determine that positioning is not normal when the number of satellites required for positioning cannot be acquired.

Here, a data storage unit for storing data relating to a work area in which the autonomous vehicle actually travels autonomously is provided, and the determination means determines whether the current position of the autonomous vehicle measured by the position detection means is present. If the data on the work area is different from the data by a reference value or more, it may be determined that there is an error in the information on the positioning.

[0016]

In such a configuration, if it is determined that the positioning is not normal, the autonomous driving is stopped and the recovery to the normal state is waited for a fixed time. The temporary positioning abnormality can be expected to be recovered by this standby, and when recovered, the suspended autonomous driving is resumed. As a result, even if a positioning error occurs, autonomous driving can be continued as long as it is temporary.

[0017]

FIG. 1 is a side view schematically showing a lawn mowing vehicle according to this embodiment. This lawn mowing vehicle has a body part 1, a lawn mowing work machine 2 attached to the front of the body part 1, and wheels 3a and 3b. A GPS receiving antenna 4, a wireless communication receiving antenna 5, and a geomagnetic sensor 6 are mounted on the vehicle body 1. The work machine 2 has a plurality of cutter units, and can be moved up and down by being rotatably attached to the vehicle body 1. A control device including a GPS device and a dead reckoning navigation device is mounted on the vehicle body 1. A wheel encoder 7 is mounted on the shaft of the wheel 3a.
The wheel encoder 7 is a sensor that detects rotation of a wheel.

FIG. 2 is a block diagram of the control device of the lawn mowing vehicle. Dead reckoning position detecting section 11 and differential GPS (hereinafter referred to as D-GPS) position detecting section 12
Thus, the traveling position of the lawn mowing vehicle can be recognized. The dead reckoning position detection unit 11 calculates the running history from a reference point to measure the current position of the work vehicle. The running history is obtained by accumulating the running distance measured by the wheel encoder 7 according to the change in the running direction measured by the geomagnetic bearing sensor 6.

In the D-GPS position detecting section 12, the GP
The current traveling position is measured based on the radio wave emitted from the S satellite and the differential information obtained from the fixed station. Radio waves from GPS satellites are received via a GPS receiving antenna 4. On the other hand, radio waves from the fixed station are received via the receiving antenna 5. As is well known, the measurement of the self-position using only radio waves emitted from GPS satellites has a large error. Therefore, in order to remove the error of the in-phase component in the measured value, the position of the fixed point installed at a known point is observed. Then, the correction information obtained based on the position observation is fed back to the autonomous vehicle. For example, when the position method is used, synchronization is performed so that the GPS satellites captured by both the receiver on the working vehicle side and the receiver on the fixed station side are the same, and information on the absolute position obtained from both is subtracted. I do. By performing such D-GPS positioning, the self-position of the traveling vehicle can be accurately measured.

In the autonomous driving mode, the control unit 13
Controls the drive control unit 14 and the steering control unit 15 based on the detection signals from the D-GPS position detection unit 12 and the dead reckoning position detection unit 11 so as to travel toward the target point. The drive control unit 14 controls a hydraulic motor using an engine (not shown) as a drive source by converting a control signal from the control unit 13 into a control amount corresponding to the control signal. The driving force of the traveling vehicle is generated by the hydraulic motor. Further, the steering control unit 15 operates a steering mechanism (not shown) by converting a control signal from the control unit 13 into a control amount corresponding to the control signal. The control unit 13
Accesses the data storage unit 16 as necessary,
Desired data is read from the data storage unit 16 or written into the data storage unit 16. In addition, working machine 2
Is also controlled by the control unit 13, and the lifting mechanism is operated via a lifting control unit (not shown).

In the data storage section 16, programs and data necessary for operating the work vehicle are stored in a non-volatile area (for example, a ROM area). In addition, the terrain data relating to the actual work field and the data of the work procedure can be rewritten in an area (for example, RAM or EEP).
ROM area).

The positioning information check section 17 is provided with a GPS (D-
It is determined whether positioning by GPS (including GPS) is normal. The positioning abnormality that has occurred includes a temporary one and a permanent one. The temporary positioning abnormality is resolved after a certain period of time has passed. A typical case in which a temporary abnormality occurs is a case where the satellite cannot be captured because it is blocked by a building or the like near the work machine. There is also a temporary positioning abnormality due to multipath. Multipath is generated by reflection of radio waves on a building or the like, and the radio waves reach the autonomous vehicle via a plurality of routes. Such a multipath
Interference with a direct wave causes a reception failure. In some cases, the D-GPS position detector 12 performs positioning based on such a reflected wave instead of a direct wave. Since the path of the reflected wave is longer than that of the direct wave, a large error occurs in positioning. On the other hand, a permanent positioning abnormality is an abnormality in which recovery cannot be expected even after a certain time has elapsed. As a case where such an abnormality occurs, there is a failure of the system itself such as a failure of the GPS receiving antenna 4 and a failure of the D-GPS position detecting unit 12.

(Monitoring of Reception Status) Such a positioning abnormality may be caused, for example, by causing a radio wave emitted from a GPS satellite to
It may be determined that the error occurred when the PS receiving antenna 4 could not be effectively received. If a reception failure due to shielding of a building or a multipath occurs, the reception status temporarily deteriorates. By monitoring this, it is possible to determine a positioning abnormality.

(Monitoring of output state) In place of monitoring of the reception state described above, the D-GPS position detection unit 12
The occurrence of a positioning error may be determined by monitoring the output from the GPS. If there is a failure in the system itself, if the satellite cannot be captured due to being interrupted by a building or the like near the work machine, or if a reception failure due to multipath occurs, the positioning information is output from the D-GPS position detection unit 12. Not done. Therefore, by monitoring the output state of the positioning information from the position detection unit 12, it can be determined that the positioning is abnormal.

(Checking of Positioning Information) If the positioning information output from the D-GPS position detecting section 12 is abnormal, it is possible to determine that a positioning abnormality has occurred. For example, when the position detection unit 12 has performed positioning based on the reflected wave by multipath, the positioning information indicates a point far from the original point. Therefore, D-GP
If the positioning result obtained from the S position detecting unit 12 differs from the data related to the work area where autonomous driving is actually performed stored in the data storage unit 16 by a reference value or more, an error occurs in the positioning result. It may be determined that there is. For example, when the actual positioning is offset by a predetermined threshold or more from a certain target point of the GPS, it can be determined that there is an error in the positioning. In addition, if the positioning result actually indicates a point outside the work area, and the point deviates from the area surrounding the work area (that is, the outer edge) by a threshold or more, it can be determined that the positioning is abnormal. . Also, it is of course possible to determine that the positioning is abnormal when there is a violation of the data rule of the positioning information, such as a checksum error.

(Monitoring of Number of Captured Satellites) In addition, when the number of GPS satellites required for positioning is not captured, it may be determined that a positioning abnormality has occurred. For example, the number of satellites that have been captured decreases, for example, the satellites cannot be captured by the number required for positioning because they are shielded by buildings.

As described above, there are various methods for determining whether or not a positioning error has occurred, and the above-described example is the most typical example. It should be noted that a plurality of such criteria may be applied in combination in order to more accurately determine a state in which positioning has become abnormal.

The positioning information check unit 17 determines the presence or absence of a positioning error based on the above-described method, and outputs a signal indicating a positioning error to the control unit 13 when there is an error.

FIG. 3 is a main flowchart of the traveling control. The lawn mowing vehicle has three modes: an autonomous traveling mode, an abnormality processing mode executed when positioning is not normal, and an engine stop as a final means when an abnormality occurs. These modes are based on the flag GP
It is specified by the state of S and the flag STOP. The relationship between the state of the flag and the specified mode is as follows. Note that the flow of FIG. 3 is repeatedly executed at predetermined intervals. Accordingly, the travel control in the current mode is stopped in accordance with the change of the flag, and the travel control in the changed mode is executed. The flag STOP is set to 0 as an initial setting.

FIG. 4 is a flow chart of the traveling control in the autonomous traveling mode. As long as the flag GPS is 1, this flowchart is repeatedly executed, and when the flag GPS becomes 0, the execution is stopped. First, D-GPS
The control unit 13 calculates the current position of the work vehicle based on the positioning information from the position detection unit 12 and the dead reckoning position detection unit 11 (step 401). This calculated position is compared with the current target point, and it is determined whether or not the work vehicle has reached the target point (step 402). If it is determined that the work vehicle has not reached the target point, step 40
Proceed to 4. On the other hand, if it is determined that the target point has been reached, the next target point stored as work data in the data storage unit 16 is reset as a new target point (step 403). , And proceed to step 404.

In step 404, a direction (target traveling azimuth) to travel toward the target point is calculated based on the target point and the calculated current position. Then, the traveling azimuth of the work vehicle at the present time is read from the geomagnetic sensor 6 (step 405), and the steering amount of the steering mechanism is calculated based on the target traveling azimuth and the current traveling azimuth (step 406). By operating the steering mechanism, the steering control unit 15 causes the work vehicle to travel toward the target point (Step 407).

Hereinafter, the traveling control in the case where an abnormality has occurred in the GPS positioning will be described with reference to FIGS. FIG. 5 is a flowchart for determining the mode switching, and this flow is repeatedly executed at predetermined intervals. FIG. 6 is a traveling control flowchart in the abnormality processing mode.

First, while the work vehicle is normally running autonomously (while the flag GPS is set to 1), the path of step 501 → step 502 → (Return) in FIG. 5 is repeatedly executed. . When an abnormality occurs in positioning during autonomous traveling (step 502), the flag GPS is changed from 1 to 0 (step 503). This positioning abnormality is checked by the positioning information check unit 17 based on the set criteria.

At step 503, the flag GPS is set to 0.
When the flag STOP is changed to the initial setting of 0, as shown in FIG. 3, the traveling control in the autonomous traveling mode is stopped, and the traveling control in the abnormality processing mode is started. As shown in the traveling control flowchart of the abnormality processing mode in FIG. 6, in this mode, the work vehicle first stops (step 601), and then stands by for a predetermined period (step 602). Then, after a lapse of a predetermined time, the work vehicle moves on the predetermined route by a predetermined distance (step 603). The important thing in this step 603 is to increase the possibility that the normal state can be restored by actively changing the reception environment. Therefore, the work vehicle is forcibly moved to a point different from the standby point without autonomous traveling. Various algorithms are conceivable for this movement. For example, the vehicle may be advanced in a programmed direction, or the route that has already traveled may be advanced based on the travel history.

Under a series of traveling control of stopping, waiting, and moving the traveling vehicle in the abnormal processing mode, the mode switching determination flowchart of FIG. 5 is repeatedly executed at predetermined intervals. First, in step 501, since the flag GPS is 0, the process proceeds to step 504. In step 504, the positioning information check unit 17 determines whether or not the generated positioning abnormality has been recovered. If the positioning abnormality has recovered, the flag GPS is changed from 0 to 1 (step 505). As a result, the abnormality processing mode is stopped, and the autonomous traveling mode is restarted.

If it is determined in step 504 that the positioning abnormality that has occurred does not recover, the process proceeds to step 506. In step 506, it is determined whether or not the time elapsed since the occurrence of the positioning abnormality has exceeded the time limit. If it has not elapsed, the process proceeds to (Return) and the flow is executed again. On the other hand, if the elapsed time exceeds the time limit in step 506, the flag STOP is changed from 0 (initial setting) to 1 in step 507. As a result, the abnormality processing mode for recovering the positioning abnormality is stopped, and as a final measure, the engine of the work vehicle is stopped. After the engine has stopped, as in the prior art, a recovery operation is required such that the operation manager goes to the stop location and recovers the state.

As can be understood from the above description, when a positioning error occurs, the autonomous traveling is stopped, the work vehicle stops, and
Stand by at the stop place for a predetermined time. Unlike the FM broadcasting and the television broadcasting, the GPS tends to prevent the trouble caused by the multipath from continuing for a long time because the satellite transmitting the radio wave is constantly moving. Therefore, by setting the standby time appropriately, it is possible to expect a temporary recovery from the positioning abnormality even when the work vehicle is simply made to wait.

Next, if recovery is not possible even after waiting,
An attempt is made to recover a positioning error by forcibly moving the position of the work vehicle. For example, temporary inability to position due to the shielding of buildings and trees near the work vehicle may be eliminated by changing the position of the work vehicle. In particular,
When lawn mowing is performed at a golf course, since the shrub is very local, it is expected that the positioning vehicle will be recovered by moving the work vehicle.

If the predetermined time limit is exceeded without recovering from the positioning abnormality, the operation of the drive source such as the engine is stopped as a final emergency measure. If the standby time, the direction of movement after the standby, and the time limit are set appropriately, it is expected that a considerable amount of positioning abnormality will be recovered, and autonomous driving must be finally stopped by permanent positioning. Most likely due to inability.

As described above, in the prior art, when the positioning cannot be performed, the autonomous driving is uniformly stopped without performing any recovery processing, and the engine is stopped. On the other hand, in the present embodiment, whether the abnormality has been recovered is monitored for a time limit before the engine is stopped. The engine is stopped for the first time when the time limit elapses without recovery from the abnormality. Therefore, as compared with the related art, even if a positioning error occurs, the possibility that the autonomous traveling is finally interrupted can be reduced, and the work efficiency in the autonomous traveling can be improved.

[0041]

As described above, according to the present invention, even if a positioning error occurs, it is possible to reduce the possibility that the autonomous driving will eventually be interrupted. Thereby, it is possible to improve the work efficiency of the work associated with the autonomous traveling.

[Brief description of the drawings]

FIG. 1 is a side view schematically illustrating a lawn mowing vehicle according to an embodiment.

FIG. 2 is a block diagram of a control device for a lawn mowing vehicle.

FIG. 3 is a main flowchart of traveling control.

FIG. 4 is a control flowchart of an autonomous driving mode.

FIG. 5 is a flowchart of a drive mode switching determination.

FIG. 6 is a control flowchart of an abnormality processing mode.

[Explanation of symbols]

1 body part, 2 lawn mowing work machine, 3a, b wheels, 4
GPS receiving antenna, 5 Wireless communication receiving antenna, 6 Geomagnetic sensor, 7 Wheel encoder, 11
Dead reckoning position detector, 12 D-GPS position detector, 1
3 control unit, 14 drive control unit, 15 steering control unit, 1
6 data storage unit, 17 positioning information check unit

Continued on the front page F term (reference) 2B043 AA04 AB20 BA08 BA09 BB11 DA17 EB03 EB04 EB05 EB08 EB10 EB15 EC12 ED01 2B083 AA01 BA12 BA16 5H301 AA03 BB12 DD07 DD17 FF11 GG12 GG16 MM07 5J062 BB01 CC07 CC07

Claims (9)

[Claims] 1. An autonomous driving method in which a current position of a traveling vehicle is measured by receiving a radio wave emitted from a satellite and autonomous traveling is performed based on the positioning. Stopping the autonomous traveling of the traveling vehicle; determining whether the positioning has returned to a normal state; and, until a predetermined period elapses from the suspension of the autonomous traveling, Restarting the autonomous traveling of the traveling vehicle when the positioning recovers to a normal state. 2. When the radio wave emitted from the satellite cannot be received, when the information on the positioning is not obtained, when the information on the positioning is obtained, but when an error of the information is detected, The autonomous driving method according to claim 1, wherein the positioning is determined to be abnormal when at least one of the cases where the number of satellites required for the positioning cannot be acquired is satisfied. 3. Following the step of stopping the autonomous driving,
The autonomous traveling method according to claim 1, further comprising a step of stopping the traveling vehicle for a predetermined period. 4. The method according to claim 1, wherein the step of determining whether or not the positioning has returned to a normal state is performed during an abnormality processing mode for setting the traveling vehicle to a predetermined traveling state. The autonomous driving method according to claim 1, wherein: 5. The abnormality processing mode according to claim 4, wherein the traveling vehicle travels in a preset direction.
Autonomous driving method described in. 6. A step of stopping an operation of a drive source for driving the traveling vehicle when the positioning does not return to a normal state during a predetermined period after the suspension of the autonomous traveling. 2. The method according to claim 1, further comprising:
Autonomous driving method described in. 7. An autonomous vehicle that performs positioning based on the current position of a traveling vehicle by receiving radio waves emitted from a satellite and performs autonomous traveling based on the positioning, receives radio waves emitted from a satellite. By means of position detecting means for positioning the current position of the autonomous vehicle, determining means for determining whether the positioning is normal, output from the position detecting means, and output from the position detecting means Control means for controlling the travel of the autonomous vehicle based on the control means, the control means stops the autonomous travel of the autonomous vehicle when it is determined that the positioning is not normal,
A control unit that restarts the autonomous traveling of the autonomous traveling vehicle when the positioning recovers to a normal state during a predetermined period from the suspension of the autonomous traveling. Traveling car. 8. The information processing apparatus according to claim 1, wherein the determining unit obtains information on the positioning when the radio wave emitted from the satellite is not received, or when the information on the positioning is not obtained. The method according to claim 7, wherein the positioning is determined to be abnormal when the detection is performed or when at least one of the cases where the number of the satellites required for the positioning cannot be acquired is satisfied. Autonomous vehicles. 9. A data storage unit for storing data relating to a work area in which the autonomous vehicle actually performs autonomous traveling, wherein the determining unit determines a current state of the autonomous vehicle measured by the position detecting unit. 9. The autonomous vehicle according to claim 8, wherein when the point is different from the data on the work area by a reference value or more, it is determined that there is an error in the positioning information.