Signal processing method and performance tests on weighting-sensor-based measuring system of output quantity for a seeding and fertilizing applicator

In terms of a weighting-sensor-based measuring system of output quantity for a seeding and fertilizing applicator, a signal processing method which could reliably obtain real-time output quantity was designed by collecting and analyzing the signals of the measuring system in the field. This method was consisted of several procedures as follow: low-pass filtering, mean filtering after high-frequency sampling, moving filtering and linear fitting. The low-pass filter was mainly used to eliminate the high frequency vibration interference produced by the interaction between the rotary cultivator and the soil during field operation. The mean filtering after high-frequency sampling aimed at weakening the random vibration interference. The main function of moving filtering was to remove the low-frequency interference. And the linear fitting was applied in the initial and terminal stages of the sowing and fertilizing output quantity detection in order to obtain more reliable gross output quantity of sowing and fertilizing In order to test the performance of the signal processing method, the field tests of sowing and fertilizing output quantity were carried out. During the tests, 3 levels of target sowing and fertilizing quantity (150Kg/ha, 300Kg/ha, 375Kg/ha for seeding, 225Kg/ha, 375Kg/ha, 525Kg/ha for fertilizing), and 2 levels of vehicle speeds (approximately 2Km/h and 3Km/h respectively) were set to carry out multi-factor cross experiments. Each kind of test repeated 3 times and had a testing distance around 300m in the field. Field test results showed that the maximum relative error of cumulative output quantity was 4.88%, the average relative error was 2.62%, and the standard deviation of relative error was 1.7%. The linear correlation coefficient R-2 between the measured output quantity and the actual output quantity was 0.998. It can be concluded that the designed signal processing method can reliably extract the effective signal of the weighing-sensor-based measuring system of output quantity, and it is expected to provide real-time feedback signal for the output quantity control system and improve the intelligent operation level of the seeding and fertilizing machine. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.