1. A harvester capable of autonomous travel in a field, the harvester comprising: a harvesting unit that harvests a crop from the field; a conveyance device that conveys, toward the rear of a harvester body, a whole culm of the harvested crop harvested by the harvesting unit; a detection sensor that detects a drive speed of the conveyance device; and a clog determining unit that determines a clog of the harvested crop in the conveyance device on the basis of the drive speed, wherein the clog determining unit outputs a vehicle stop command that stops the harvester body when the drive speed becomes lower than a pre-set first threshold during the autonomous travel.

2. The harvester according to claim 1, wherein a second threshold set higher than the first threshold is provided; and when the drive speed becomes a value between the first threshold and the second threshold, the clog determining unit outputs a speed reduction command that reduces a vehicle speed of the harvester body in stages, in accordance with a magnitude of the drive speed.

3. The harvester according to claim 1 or 2, further comprising: a travel mode managing unit capable of switching a travel mode to an autonomous travel mode in which the autonomous travel is executed and to a manual travel mode in which manual travel is executed, wherein the travel mode managing unit switches the travel mode to the manual travel mode when the vehicle stop command has been output by the clog determining unit.

4. The harvester according to any one of claims 1 to 3, further comprising: a travel mode managing unit capable of switching a travel mode to an autonomous travel mode in which the autonomous travel is executed and to a manual travel mode in which manual travel is executed; and a notification unit capable of making a notification indicating that the drive speed has decreased, wherein when the drive speed becomes lower than the first threshold while the travel mode is the autonomous travel mode, the clog determining unit outputs the vehicle stop command, and outputs, to the notification unit, a notification command for making a notification of the decrease in the drive speed, and when the drive speed becomes lower than the first threshold while the travel mode is the manual travel mode, the clog determining unit outputs the notification command to the notification unit without outputting the vehicle stop command.

5. A harvester comprising: a harvesting unit that harvests a harvested crop from a field; and a conveyance device that conveys the harvested crop harvested by the harvesting unit, wherein the conveyance device includes a conveyor chain, a conveyor screw, or both; and the harvester further comprises1 a speed obtaining unit that obtains rotational speed information, the rotational speed information being information indicating a rotational speed of the conveyor chain or the conveyor screw; and a clog determining unit that determines whether or not the conveyance device is clogged on the basis of the rotational speed information obtained by the speed obtaining unit.

6. The harvester according to claim 5, wherein the conveyance device includes a rotating body that rotationally drives the conveyor chain or the conveyor screw; the rotational speed information is a rotational speed of the rotating body; and the clog determining unit determines that the conveyance device is clogged when the rotational speed of the rotating body obtained by the speed obtaining unit is less than or equal to a prescribed rotational speed.

7. The harvester according to claim 5 or 6, further comprising: a clog instance control unit that stops travel or reduces a travel speed when the clog determining unit has determined that the conveyance device is clogged.

8. The harvester according to claim 7, wherein the conveyance device includes a rotating body that rotationally drives the conveyor chain or the conveyor screw; the rotational speed information is a rotational speed of the rotating body and the harvester further comprises1 a first determining unit that determines whether or not the rotational speed of the rotating body is less than or equal to a prescribed first speed; and a deceleration control unit that reduces the travel speed when the first determining unit has determined that the rotational speed of the rotating body is less than or equal to the first speed, wherein the clog determining unit is configured to determine that the conveyance device is clogged when the rotational speed of the rotating body obtained by the speed obtaining unit is less than or equal to a prescribed second speed slower than the first speed; and the clog instance control unit stops travel when the clog determining unit has determined that the conveyance device is clogged.

9. A harvester comprising: an engine; a harvesting unit including a cutting device that cuts planted culm in a field and an auger that is driven by power from the engine and feeds the harvested culm laterally in a lateral width direction of a harvester body; a conveyance device that conveys the harvested culm to toward the rear of the harvester body; a threshing device that receives the harvested culm conveyed by the conveyance device and carries out a threshing process; a rotation speed detection sensor that detects a rotation speed of the auger; and an auger state determining unit that determines a drive abnormality in the auger on the basis of a detection signal from the rotation speed detection sensor.

10. The harvester according to claim 9, wherein the auger state determining unit determines a clog in the auger on the basis of a drop in the rotation speed of the auger.

11. The harvester according to claim 9, wherein the auger state determining unit determines a clog in the auger on the basis of a rate of decrease in the rotation speed of the auger relative to a rotation speed of the engine.

12. The harvester according to claim 10 or 11, wherein when the auger state determining unit has determined that there is a clog, the auger state determining unit reduces a vehicle speed.

13. The harvester according to any one of claims 10 to 12, wherein a vehicle body is stopped when a clog has continued for a set amount of time.

14. The harvester according to any one of claims 9 to 13, wherein when the auger state determining unit has determined the drive abnormality, a drive abnormality warning is made.

WE CLAIM:
1. A harvester capable of autonomous travel in a field, the harvester
comprising:
a harvesting unit that harvests a crop from the field;
a conveyance device that conveys, toward the rear of a harvester body, a whole culm of the harvested crop harvested by the harvesting unit;
a detection sensor that detects a drive speed of the conveyance device; and
a clog determining unit that determines a clog of the harvested crop in the conveyance device on the basis of the drive speed,
wherein the clog determining unit outputs a vehicle stop command that stops the harvester body when the drive speed becomes lower than a pre-set first threshold during the autonomous travel.
2. The harvester according to claim 1,
wherein a second threshold set higher than the first threshold is provided; and
when the drive speed becomes a value between the first threshold and the second threshold, the clog determining unit outputs a speed reduction command that reduces a vehicle speed of the harvester body in stages, in accordance with a magnitude of the drive speed.
3. The harvester according to claim 1 or 2, further comprising:
a travel mode managing unit capable of switching a travel mode to an autonomous travel mode in which the autonomous travel is executed and to a manual travel mode in which manual travel is executed,
wherein the travel mode managing unit switches the travel mode to the manual travel mode when the vehicle stop command has been output by the clog determining unit.
4. The harvester according to any one of claims 1 to 3, further
comprising:
a travel mode managing unit capable of switching a travel mode to an autonomous travel mode in which the autonomous travel is executed and to a manual travel mode in which manual travel is executed; and

a notification unit capable of making a notification indicating that the drive speed has decreased,
wherein when the drive speed becomes lower than the first threshold while the travel mode is the autonomous travel mode, the clog determining unit outputs the vehicle stop command, and outputs, to the notification unit, a notification command for making a notification of the decrease in the drive speed, and when the drive speed becomes lower than the first threshold while the travel mode is the manual travel mode, the clog determining unit outputs the notification command to the notification unit without outputting the vehicle stop command.
5. A harvester comprising:
a harvesting unit that harvests a harvested crop from a field; and
a conveyance device that conveys the harvested crop harvested by the harvesting unit,
wherein the conveyance device includes a conveyor chain, a conveyor screw, or both; and
the harvester further comprises1
a speed obtaining unit that obtains rotational speed information, the rotational speed information being information indicating a rotational speed of the conveyor chain or the conveyor screw; and
a clog determining unit that determines whether or not the conveyance device is clogged on the basis of the rotational speed information obtained by the speed obtaining unit.
6. The harvester according to claim 5,
wherein the conveyance device includes a rotating body that rotationally drives the conveyor chain or the conveyor screw;
the rotational speed information is a rotational speed of the rotating body; and
the clog determining unit determines that the conveyance device is clogged when the rotational speed of the rotating body obtained by the speed obtaining unit is less than or equal to a prescribed rotational speed.
7. The harvester according to claim 5 or 6, further comprising:
a clog instance control unit that stops travel or reduces a travel speed

when the clog determining unit has determined that the conveyance device is clogged.
8. The harvester according to claim 7,
wherein the conveyance device includes a rotating body that rotationally drives the conveyor chain or the conveyor screw;
the rotational speed information is a rotational speed of the rotating body and
the harvester further comprises1
a first determining unit that determines whether or not the rotational speed of the rotating body is less than or equal to a prescribed first speed; and
a deceleration control unit that reduces the travel speed when the first determining unit has determined that the rotational speed of the rotating body is less than or equal to the first speed,
wherein the clog determining unit is configured to determine that the conveyance device is clogged when the rotational speed of the rotating body obtained by the speed obtaining unit is less than or equal to a prescribed second speed slower than the first speed; and
the clog instance control unit stops travel when the clog determining unit has determined that the conveyance device is clogged.
9. A harvester comprising:
an engine;
a harvesting unit including a cutting device that cuts planted culm in a field and an auger that is driven by power from the engine and feeds the harvested culm laterally in a lateral width direction of a harvester body;
a conveyance device that conveys the harvested culm to toward the rear of the harvester body;
a threshing device that receives the harvested culm conveyed by the conveyance device and carries out a threshing process;
a rotation speed detection sensor that detects a rotation speed of the auger; and
an auger state determining unit that determines a drive abnormality in the auger on the basis of a detection signal from the rotation speed detection sensor.

10. The harvester according to claim 9,
wherein the auger state determining unit determines a clog in the auger on the basis of a drop in the rotation speed of the auger.
11. The harvester according to claim 9,
wherein the auger state determining unit determines a clog in the auger on the basis of a rate of decrease in the rotation speed of the auger relative to a rotation speed of the engine.
12. The harvester according to claim 10 or 11,
wherein when the auger state determining unit has determined that there is a clog, the auger state determining unit reduces a vehicle speed.
13. The harvester according to any one of claims 10 to 12,
wherein a vehicle body is stopped when a clog has continued for a set amount of time.
14. The harvester according to any one of claims 9 to 13,
wherein when the auger state determining unit has determined the drive abnormality, a drive abnormality warning is made.