Camera directs knives of the Photoheyler rotary hoe with precision

The Photoheyler rotary hoe, equipped with four cameras, weeds within the row. Many machines can do this, but the rotating knives make this machine unique. - Photos: Michel Velderman

The hoe from the German machine manufacturer Photoheyler weeds within the row. Many machines can do this, but the rotating knives make this machine unique. Commonly, hoes use reciprocating knives. Another unique feature is keeping the hoe in the row. The cameras recognize the rows and steer the tractor wheels, while the support wheels on the hoe beam steer synchronously. The rotors are automatically kept at the correct depth using sensors.

The rotary hoe from the German manufacturer Photoheyler has been in development for some time but has only recently hit the market. Future Farming observes the hoe in action in a valerian crop. It’s a remarkable sight: twelve rotors in a row, moving along and striking down weeds between the plants.

Unique technology is developped behind the machine. The valerian is planted on sandy soil. Despite an irregular plant stand and uneven ground due to a wet planting season last year, the hoe performs well. As long as there is about 10 centimeters of space between plants, the Photoheyler can nearly completely weed the field.

Fully autonomous operation without GPS

The tractor operates fully autonomously with the Photoheyler rotary hoe, without GPS. The driver only steers at the headland. Cameras recognize the crop plants and rows, controlling the tractor’s steering. The support wheels on the hoe also steer. These corrections are subtle movements that are almost imperceptible to the eye.

Photoheyler has extensive experience weeding sugar beets in Germany. Although valerian wasn’t initially on the list of crops, it was only a matter of time. Images of some plants in a new crop are sent to Photoheyler’s headquarters in southern Germany. Three hours later, the machine can start working. This process is repeated several times to optimize recognition.

For a completely new crop, the Photoheyler rotary hoe can find its way within a day and learn new skills within hours. In the Netherlands, the hoe successfully recognized planted spinach within a day. It can identify a sugar beet at the two-leaf stage.

Fine-tuning the rotor speed

Photoheyler provides a 6-meter wide hoe beam with parallelograms at 50-centimeter row spacing. More or fewer parallelograms can be installed for different row spacings, but conversion during the season is not recommended. Each element has its own hydraulics and power supply, which are well-organized but not suited for frequent adjustments. It can be adapted to significant differences in plant spacing.

The rotor knives come in different widths. The narrower the plant spacing, the narrower the knives should be. With plant spacing of 20 to 25 centimeters, a 10-centimeter knife works well. Users can also set the rotor speed and frequency, such as having the rotor make one, two, or three passes between two plants.

The upper arms of the parallelograms have integrated hydraulic blocks. Parallelograms can lift and lower individually. Another unique feature is the steering support wheels.

Adjusting work depth

The tractor, autonomously guided by the cameras, precisely follows the rows. The driver can adjust the virtual line that the Photoheyler rotary hoe follows. The work depth of the parallelograms is manually adjustable with a spindle on the support wheels. The beam and parallelograms are from Hatzenbichler, meaning all types of Hatzenbichler hoe knives and leaf protectors can be used.

The rotors are suspended from separate parallelograms with automatic height adjustment. On the screen, the driver can correct the work depth as desired. Individual elements can also be lifted to avoid obstacles or when dealing with uneven headlands. When all rotors are raised, the hoe beam can be used as a conventional hoe for between-row weeding, with cameras still guiding along the rows. This allows for a significant increase in driving speed.

The rotors are electrically controlled and suspended in parallelograms with automatic sensor-guided height adjustment.

Potential and limitations of the Photoheyler rotary hoe

Changing row spacings during the season is theoretically possible but not practical. The parallelograms can be moved or removed, but the installation of hydraulic lines and power supply makes this challenging.

The machine works better with plants spaced evenly in the row. Lettuce, a crop easily recognized by cameras and regularly spaced, is ideal for a conventional hoe but not for the Photoheyler. The rotating knives can throw soil onto the lettuce heads, a concern also for competitors using reciprocating knives.

Another point to consider is the camera-controlled tractor steering via a CAN-bus system. Connecting the system requires a tractor equipped with a steering valve. If the tractor has GPS, it typically also has this feature. According to the manufacturer, connecting is almost plug-and-play with some of the latest tractors equipped with Isobus TIM.

Regarding capacity, the manufacturer claims a driving speed of 3 kilometers per hour is possible, depending on the crop and plant spacing. In many cases, a speed of 2 kilometers per hour is more common, comparable to competitors using reciprocating hoes.