Modification of Planter
Navigation sensor for grain cart on interseeder:
The interseeder selected for this project is one that was designed and built by Fargo Products, LLC in 2016. The planting and fertilizer row units for the interseeder are attached to a three-point hitch toolbar. A wheeled grain cart is towed behind the interseeder. An initial problem with the interseeder operation was the grain cart wheels often rolled over the rows of standing corn. In 2017, the accuracy of a navigation system for the grain cart attached to the interseeder, and the system performance were evaluated.
We selected a sonic implement guidance system for the grain cart from Reichhardt Electronic Innovations. The sonic guidance system is based on the ultrasound, measuring distance from a trameline, row, hill, marker track or wheel track. The reasons for choosing a sonic guidance system include: i) the sensors are not sensitive to dust; ii) the sensors function independent of daylight and weather conditions, and ii) the system is less costly than GPS guidance systems.
Sensor Features and Installation:
We found the path of motion by changing the position of the grain cart tires. The sensor finds the middle of the rows and continually sends correction signals to the angle sensor on the grain cart, changing the angle of the tires. The interseeder includes a hydraulic system that makes changing the position of the tires possible.
Ultrasonic devices for measuring distance are readily available. They typically work in the range 100 mm to 10 m with an accuracy of 99%. Distance is calculated from the time it takes for an ultrasonic signal to reach and be reflected back from the target. As the signal may be back from a number of objects in its field of view only the nearest is recorded. In other words, ultrasonic sensors generate high frequency sound waves and evaluate the echo, which is received back by the sensors.
Installation required the base kit implement adapter harnessing, ISO display and sensors for guiding the implement. An Implement Guidance Base kit supports the iBox LT controller, which is intended for a permanent installation in the tractor cab area. The kit also includes a joystick for manual control, switching guidance functions, and a universal harnessing to adapt to existing implement/hitch-specific components.
When using sonic sensors, the mounting of the sensors was critical to the performance of the system. The sonic sensors are the “eyes” of the system. Each ½” discrepancy between sensor readings results in an additional ½” error in system performance. The mounting solution allows both vertical and lateral adjustments to the sensor mounts. There are four sensor systems. Sensors S1, S2, S3 and S4 were positioned from left to right with respect to the direction of travel. Sensor Orientation is as shown as viewed from the front of the implement.
The Ultra-Sonic Sensors include internally adjustable carrier arms, which can be rotated +/- 75 degrees of vertical.
The sensor location is dependent on the steering mode configuration. The usable range of the Ultra-Sonic sensors is from 10” to possibly as far as 51”. Often the surface/angle, which the sensor is pointed to, limits this range. The ideal mounting window is between 20” and 28”, but is usable at closer distances (as long as it’s beyond the 10” minimum). Sonic sensors can recognize plants when about 4” tall.
Field Tests:
Starting working with the system, we realized that the hydraulic steering system on the grain cart had issues and did not precisely follow the rows. One of the issue we found was that every time we turned the interseeder around the cylinder used for steering the grain cart was always in a different position when the wheels straighten out. Sometimes after the turning the interseeder and grain cart around, the cylinder was at the end of its stroke, either all the way in or out, resulting in the inability to steer the grain cart left or right.
Troubleshooting:
After analyzing the situation, we realized that there was too much tolerance in the steering linkages; enough tolerance to equal about 3 inches of stroke on the steering cylinder. The solution was to weld the brackets that were moving.