Development and performance evaluation of an automatic section control system for corn precision planters

Abstract

Overlap- planted area (OPA) tends to appear when large precision planters with more row units were employed in planting corn for the operator would typically need to drive the planter into the already planted area and decide when to stop planting to ensure complete coverage. This will lead to an increase in the cost of seeds and potential yield losses. In this paper, an automatic section control (ASC) system for corn precision planters was proposed to address above problems, the working principle of the system is to build a database of planted areas (DAPA) by collecting coordinates of the planted area during planting, and constantly query whether the coordinates of the seed tube egress point (STC) of each row unit is in DAPA, finally control the start-stop state of the corresponding brushless DC motors (BLDCM) according to the query results. A mathematical model calculating STC of each row unit in real-time according to coordinates acquired by GPS receivers is established. In addition, the system adopts controller area network (CAN) bus distributed control mode, which makes independent control of the row unit possible and offers good extensibility. Algorithms including Geohash algorithm, algorithm of discarding the same prefix, and dynamic trie data structure for improving the efficiency and performance of the ASC systems were proposed. Laboratory experiments were conducted at five Geohash string quantities (7410, 37040, 74070, 111110, and 148,150 Geohash strings), the results demonstrate that the proposed algorithms have high efficiency and are basically not affected by the increase of DAPA scale: time consumed (t) of retrieving and inserting a Geohash string from the dynamic trie is less than 36.51 ms and 62.99 ms, respectively, and there is no significant difference in t under various Geohash string quantities (P greater than 0.05). Field experiments were conducted at three positioning frequencies (fGPS) (2, 5, and 10 Hz) and three field shape complexity (pa) (0.08, 0.10, and 0.12). The results showed that the dp value could be decreased immensely when the ASC function was turned on: under the ASC function turned off, the corresponding dp values under the pa values of 0.08, 0.1, and 0.12 are 9.17 %, 7.71 %, and 10.74 %, respectively, while once the ASC function is enabled, the dp values under all experiments conditions do not exceed 1.63 %, and the change of pa has no significant effect on the dp. As the fGPS increases from 2 Hz to 5 Hz, dp value of field 1–3 decreased significantly by 0.56, 0.39, and 0.52 percentage points, respectively. Due to the influence of processor performance, the fluctuation of dp value is not obvious when fGPS increases from 5 Hz to 10 Hz. In conclusion, the proposed ASC system has a good performance in reducing OPA and can be employed on corn precision planters to save seeds and improve yield.