4. Weeding

General description

In this task the main robot should be equipped with a crop sprayer capable of spraying water.

The robot may use the map created in task 3 to produce an optimised path that allows it to spray all of the weeds in the shortest possible time. Teams will be allowed 10 minutes to configure their robot for spraying and load an optimised path into its navigation system. The path optimisation process can be completed using a computer that is independent of the main robot, but this process must be completed within the 10 minute time window.

Alternatively, the robot may go without a map or an optimised path. Without an optimised path, it is more difficult to complete the task within 3 minutes.

The robots shall precisely spray the weeds mapped in task 3. It is not permitted to touch or pass the yellow tennis balls.

Field conditions

As in task 2 and 3 random stones are placed along the path, to represent realistic field scenario where the robot should cope with holes etc. The stones are not exceeding the level of 35 mm from the average ground level in the neighbourhood. The stones may be pebbles (diameter <35 mm) laid in the ground and large rocks that push (max 35 mm) out from the ground, both are installed. In other words, the robot must have ground clearance of this amplitude at minimum, and the robot must be able to climb over obstacles of max 35 mm high. No maize plants are intentionally missing in the end of the rows. However, due to circumstances of previous runs by other robots, it is possible that some plants in the end of the rows are damaged.

The weeds are objects represented by pink golf balls randomly distributed between the rows in the soil that only the upper half is visible. Robots may drive across or over them without a penalty. The weeds are located in a centred band of 60 cm width between the rows. No weeds are located within rows and on headlands.

Obstacles are represented by yellow tennis balls which will be placed randomly between rows and on the headland. Robots are not permitted to touch or pass the obstacles.

The location of the obstacles and weeds will be the same in tasks 3 and 4.

As in task 3, there is no requirement for the robot to drive along every row, provided all weeds are sprayed.

Rules for robots

Each robot has only one attempt. The maximum available time for the run is 3 minutes.

The robot must give an audible signal when the sprayer is operated.

The robot must spray only the weeds or the circular area around the golf ball with a diameter of 25 cm. Spraying outside this weed circle is counted as false positive, with no true positive scoring.

In the case that the robot is spraying or producing an acoustic signal without any reason, this is regarded as false positive.

Failure to spray a weed one is present (false negatives) will result in a penalty of 2 points per occurrence.


Crop plant damage by the robot will result in a penalty of 2 points per plant.

Manual intervention to move or adjust the robot will result in a penalty of 2 points for each time the robot is STOPPED.

Activating the sprayer or making an audible signal when no weed is present in that location (false positives) will result in a penalty of 1 point per occurrence.

Failure to spray a weed when one is present (false negatives) will result in a penalty of 2 points per occurrence.

The Jury will register the number of true positives, false positives and false negatives.

Each time a weed is sprayed correctly with the appropriate audible signal (true positives) 6 points will be awarded.

If a weed is sprayed correctly but without an audible signal 4 points will be awarded.

The total travelled distance will not be assessed.

If a team completes the task in less than 3 minutes, this time will be used to calculate a

bonus factor = total points x 3 minutes / measured time.

The task completing teams will be ranked by the number of points as described above.

The three best teams will be rewarded.

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