Development of a stereovision-based technique to measure the spread patterns of granular fertilizer spreaders

Centrifugal fertilizer spreaders are by far the most commonly used granular fertilizer spreader type in Europe. Their spread pattern however is error-prone, potentially leading to an undesired distribution of particles in the field and losses out of the field, which is often caused by poor calibration of the spreader for the specific fertilizer used. Due to the large environmental impact of fertilizer use, it is important to optimize the spreading process and minimize these errors. Spreader calibrations can be performed by using collection trays to determine the (field) spread pattern, but this is very time-consuming and expensive for the farmer and hence not common practice. Therefore, we developed an innovative multi-camera system to predict the spread pattern in a fast and accurate way, independent of the spreader configuration. Using high-speed stereovision, ejection parameters of particles leaving the spreader vanes were determined relative to a coordinate system associated with the spreader. The landing positions and subsequent spread patterns were determined using a ballistic model incorporating the effect of tractor motion and wind. Experiments were conducted with a commercial spreader and showed a high repeatability. The results were transformed to one spatial dimension to enable comparison with transverse spread patterns determined in the field and showed similar results

Development of an open-source, low-cost and adaptable 3D accelerometer for monitoring animal motion

Lameness is, after mastitis and reduced fertility, the third most important health problem in dairy cows. Lameness causes a significant decrease in milk production, a reduced fertility, a higher culling rate and severely deteriorates animal welfare. To help farmers in detecting lame cows, ILVO has developed the GAITWISE system which consists of a six-meter long pressure sensitive mat to detect the positions of the legs with respect to time as well as the relative pressure exerted by the legs when cows walk over it. In order to determine whether a cow is lame, measured variables (e.g. stride length, abduction, asymmetry in relative force) are compared with the previous values of the same cow by a cow specific model. To validate the measurements from the GAITWISE, an open-source, low-cost and adaptable prototype 3D accelerometer is developed. The goal is to detect the motion of the cow’s legs using accelerometers and gyroscopes in x, y and z-direction in a way that data can be obtained online in order to reconstruct the motion of a cow’s legs. For the first prototype the single-board microcontroller Arduino Nano with an Atmega 328, an open source platform, serves as the processing unit, while MPU-6050 (InvenSense, CA, USA) is used to get the raw tri-axis acceleration and angular velocity data. The MPU-6050 is designed for low power, low cost and high performance requirements of wearable sensors. The unit has a digital output and communicates with the Arduino platform through I2C. An ultra-low power module (NRF24L01+, Nordic Semiconductor, Trondheim, Norway) is used to create a network that allows to receive the data online using the 2.4 GHz ISM band. The newly developed sensor is user programmable, allowing one to choose between different ranges and resolutions for the measurement of the acceleration (±2g, ±4g, ±8g or ±16g) and the angular velocity (±250°/s, ±500°/s, ±1000°/s or ± 2000°/s). An Arduino Nano with a high power NRF24L01+ module and a rechargeable battery is placed on the neckband of the animal as an extra node in the network to amplify the signal. The receiver module contains also an Arduino Nano and a high power NRF24L01+ module and is connected to a computer to collect and process all the received data. The price for the sensor on the legs (one per leg) will be approximately € 20.5, the neckband transmitter and the receiver around € 26 and € 17 respectively, which adds up to a total of € 125. First tests showed that the prototype is able to measure accelerations with an error below 2.5 % and gyroscope values with an error below 0.3 %. A preliminary test with a walking cow showed that the sensor was able to record the acceleration and angular velocity of the cow’s legs. Moreover, the designed sensor is open source and low-cost. The main drawback of our first prototype is that after 24hrs the battery needs recharging. To be used in future tests with walking cows a smaller version of the sensor that is attached to the legs, will be designed. Therefore the Pro Mini version of the Arduino microcontroller will be used with a NRF24L01+ low power transceiver and a rechargeable battery

Measuring the dynamic mass flow from a centrifugal fertilizer spreader

Working widths of commercial centrifugal fertilizer spreaders are continuously increasing, increasing the sensitivity of the spread pattern to fertilizer and spreader properties. One very important parameter is the fertilizer mass flow rate from the hopper to the disks, since this determines the application rate on the field and has also an effect on the shape of the distribution pattern. In this study, the dynamic mass flow rate of a commercially available fertilizer spreader was evaluated for three types of fertilizer. Fluctuations of the flow rate were found and illustrate the need to consider the dynamic behavior of the mass flow rate when designing systems or procedures for measuring or simulating spread patterns of centrifugal fertilizer spreaders

Comparison of different spread pattern determination techniques

Traditionally, the performance of fertilizer spreaders is assessed using a row of collection trays aligned perpendicular to the driving direction of the tractor. For precise calibration of the spreader this technique, however, does not provide adequate insight into the spreading process since particle distributions are measured in only one spatial dimension. In this paper, two different two dimensional spread pattern determination techniques (SPDT) were tested, each consisting of a sampling method and a matching interpolation algorithm. Tests were executed under similar conditions with three commonly used types of fertilizer (CAN, NPK, KCl) with different physical properties. Results were compared with the traditional technique. The differences found illustrate the importance of using an adequate SPDT to compare spread patterns

Development of a High Irradiance LED Configuration for Small Field of View Motion Estimation of Fertilizer Particles

Better characterization of the fertilizer spreading process, especially the fertilizer pattern distribution on the ground, requires an accurate measurement of individual particle properties and dynamics. Both 2D and 3D high speed imaging techniques have been developed for this purpose. To maximize the accuracy of the predictions, a specific illumination level is required. This paper describes the development of a high irradiance LED system for high speed motion estimation of fertilizer particles. A spectral sensitivity factor was used to select the optimal LED in relation to the used camera from a range of commercially available high power LEDs. A multiple objective genetic algorithm was used to find the optimal configuration of LEDs resulting in the most homogeneous irradiance in the target area. Simulations were carried out for different lenses and number of LEDs. The chosen configuration resulted in an average irradiance level of 452 W/m2 with coefficient of variation less than 2%. The algorithm proved superior and more flexible to other approaches reported in the literature and can be used for various other applications