Testing an Online Spread Pattern Determination Sensor on a Broadcast Fertilizer Spreader

An alternative method for fertilizer spread pattern determination was developed based on predicting where individual fertilizer particles land on the ground, in contrast to the traditional method of collecting the particles in bins (ASAE Standard S341.2). A small broadcast granular fertilizer spreader (Lowery 300) was equipped with an optical sensor designed to measure the velocity and diameter of individual fertilizer particles shortly after they leave the impeller disc. The measured velocity and diameter of individual particles were input into a ballistic model that predicted where particles land on the ground. A total of over 1000 landing spots revealed the spread pattern. The results have shown that the optical sensor is capable of automatically determining the spread pattern of a fertilizer spreader on the fly. The sensor could be a key component in the development of uniformity-controlled fertilizer application systems

Development of a tabletop guidance system for educational robots

The guidance of a vehicle in an outdoor setting is typically implemented using a Real Time Kinematic Global Positioning System (RTK-GPS) potentially enhanced by auxiliary sensors such as electronic compasses, rotation encoders, gyroscopes, and vision systems. Since GPS does not function in an indoor setting where educational competitions are often held, an alternative guidance system was developed. This article describes a guidance method that contains a laser-based localization system, which uses a robot-borne single laser transmitter spinning in a horizontal plane at an angular velocity up to 81 radians per second. Sensor arrays positioned in the corners of a flat rectangular table with dimensions of 1.22 m × 1.83 m detected the laser beam passages. The relative time differences among the detections of the laser passages gave an indication of the angles of the sensors with respect to the laser beam transmitter on the robot. These angles were translated into Cartesian coordinates. The guidance of the robot was implemented using a uni-directional wireless serial connection and position feedback from the localization system. Three experiments were conducted to test the system: 1) the accuracy of the static localization system was determined while the robot stood still. In this test the average error among valid measurements was smaller than 0.3 %. However, a maximum of 3.7 % of the measurements were invalid due to several causes. 2) The accuracy of the guidance system was assessed while the robot followed a straight line. The average deviation from this straight line was 3.6 mm while the robot followed a path with a length of approximately 0.9 m. 3) The overall performance of the guidance system was studied while the robot followed a complex path consisting of 33 sub-paths. The conclusion was that the system worked reasonably accurate, unless the robot came in close proximity

An economic appraisal of the effect of tire inflation pressure for alternative tillage systems on a silty clay loam soil

Compacting soil has an adverse effect on soil properties, decreases crop productivity, and subsequently reduces farm income. Low tire inflation pressure (LTP) help in managing soil compaction and protecting the soil environment; however, there is scant economic data available on LTP in US Midwest farming systems. Hence, a 3-year study investigated the effects of LTP, compared to tires inflated to the standard tire inflation pressure systems, on crop yield and farm economy for a typical maize/soybean rotation. The effect of the two tire inflation pressure systems was factorialized with three tillage systems: deep tillage (DT, 450 mm), shallow tillage (ST, 100 mm), and no-till systems. The results showed that LTP systems increased maize (Zea mays) yield by 4.51% (2017) and 2.70% (2018) and soybean (Glycine max) by 3.70% in 2018. Annual earnings for both 200- and 800-ha farms increased for all tillage systems with LTP tires based on a partial budget analysis. The payback periods for LTP tires were very short, ranging from 0.32 years for DT on an 800-ha farm to 1.18 years for ST on a 200-ha farm. The net present value of the higher returns with LTP tires was substantial, especially for the DT system. This study shows a strong economic benefit from investments in LTP tires on silty clay loam soils in the US Midwest

Development of low-cost, root collar diameter measurement devices for pine seedlings

To assess the growth stage of pine seedlings in the field, nurseries annually measure the root collar diameter (RCD) of a large number of seedlings. Traditionally this is done manually using a slide micrometer and registration on paper, a tedious and error-prone practice. As an alternative, two generic semi-automatic diameter measurement devices were developed, based on an optical time-of-flight principle. Here the diameter was obtained using the timing information generated by the shadow of an object passing a pair of receivers. In the first method named the 'sliding-edge device', the operator manually slides the object along a guiding edge after which the diameter is measured and recorded automatically. In the second method named the 'counterbalanced device' the operator places the object on a table after which the device measures and records the diameter at the push of a button. Both devices were tested using cylindrical objects with known diameters. The sliding-edge device produced a maximum systematic error of 0.3 mm (9.5%), most likely owing to inaccurate model assumptions and a maximum variability of 0.1 mm. The counterbalanced device proved superior with a maximum systematic error of 0.1 mm (1%), virtually independent of operator skill, and a maximum variability of 0.1 mm. (c) 2006 Elsevier B.V. All rights reserved

Development of a tabletop guidance system for educational robots

The guidance of a vehicle in an outdoor setting is typically implemented using a Real Time Kinematic Global Positioning System (RTK-GPS) potentially enhanced by auxiliary sensors such as electronic compasses, rotation encoders, gyroscopes, and vision systems. Since GPS does not function in an indoor setting where educational competitions are often held, an alternative guidance system was developed. This article describes a guidance method that contains a laser-based localization system, which uses a robot-borne single laser transmitter spinning in a horizontal plane at an angular velocity up to 81 radians per second. Sensor arrays positioned in the corners of a flat rectangular table with dimensions of 1.22 m × 1.83 m detected the laser beam passages. The relative time differences among the detections of the laser passages gave an indication of the angles of the sensors with respect to the laser beam transmitter on the robot. These angles were translated into Cartesian coordinates. The guidance of the robot was implemented using a uni-directional wireless serial connection and position feedback from the localization system. Three experiments were conducted to test the system: 1) the accuracy of the static localization system was determined while the robot stood still. In this test the average error among valid measurements was smaller than 0.3 %. However, a maximum of 3.7 % of the measurements were invalid due to several causes. 2) The accuracy of the guidance system was assessed while the robot followed a straight line. The average deviation from this straight line was 3.6 mm while the robot followed a path with a length of approximately 0.9 m. 3) The overall performance of the guidance system was studied while the robot followed a complex path consisting of 33 sub-paths. The conclusion was that the system worked reasonably accurate, unless the robot came in close proximity

Development of a tracking and guidance system for a field robot

Small robots operating between crop rows need another guidance system than existing guidance systems for larger equipment. Some experiments were done to detect crop rows and to track the motion of the vehicle. Crop row detection was based on excessive green. Motion tracking was based on dynamic template matching. The applied methods have good perspectives although improvements are still necessary. The most important are combining information from several consecutive images and using information from the images itself to determine the required parameter values for dynamic template matchin