Development of 4UGS2 type double-row sweet potato harvester

Abstract: At present, the domestic potato harvest machinery suitable for working in small plot is characterized by small size, lower power, lower efficiency and single function compared with the foreign harvest machinery. There are few large and medium-sized harvesters on the market. The development of sweet potato harvester adopts the mature techniques of potato harvester, and the best method for harvesting sweet potato according to the growth status of sweet potato was not found. At the same time, the research on precision agriculture technology and intelligent equipment in China is still in its beginning stage. To promote the extensive application of modern information technology, biotechnology, agricultural science, hydraulic and electronic control technology in agricultural equipment is very important to the development of sweet potato harvest machinery. Aimed at the extrusive problems in the domestic sweet potato harvester, such as lower level of mechanical automation, deficiency of automatic alignment system and automatic depth control system, greater resistance in excavation, easy to plug and inefficient soil separation, we design and develop 4UGS2 type double-row sweet potato harvester. 4UGS2 harvester consists of rack frame drawbar and ground wheel, cutting soil disc, digging shovel, pressing grass wheel, separating and conveying device, transmission system and electronic control system. The electronic control system includes automatic alignment system and automatic depth control system, which can control the position and depth of the mining accurately. The anti-blocking mechanism of excavator can effectively ensure the smooth flow of soil, and relieve soil plugging and weeds winding so as to reduce working resistance. Automatic depth control system can adjust the digging depth in real time according to the ground condition, solving the problem of automatic control of digging depth during the operation of harvester. Two-stage soil-potato separating device and three-head shaking driving wheel device can ensure more effective separation of soil. Automatic alignment system can adjust the excavator's position in the middle of the ridge and improve the automation level and operation performance of sweet potato harvester. The harvest tests included 3 states, in which tractor driving speed is 1.95, 1.40 and 0.91 m/s, respectively. The results show that 4UGS2 harvester exhibits better performances and adaptation on the moist land with soft soil and less hardening. At the same time, the driving speed of the tractor and the separating speed of the soil-potato mechanism are the important factors that affect the quality of the harvest. The relationship between the driving speed and the separating speed should be deeply studied. When the speed of the tractor is rising, the obvious rate is reduced, the injury rate is increased, the skin-damaged rate is reduced, the productivity is increased, and the reliability is not changed much. When the driving speed is higher, due to the increase of materials per unit time and the incomplete separation of potato, the obvious rate is reduced and the injury rate is increased. As there are more materials entering the secondary separation device, the friction between sweet potato and the separation chain is alleviated and the skin-damaged rate is reduced. When the driving speed is lower, due to the decrease of materials per unit time, the obvious rate is increased and the injury rate is reduced. Meanwhile, at the end of the secondary separation mechanism, it will lead to increased wear and tear between sweet potato and separation transportation chain, resulting in a sharp increase in the skin-damaged rate. When the harvester is matched with a tractor with the rated power of 110 kW and 1.40 m/s driving speed, its working productivity achieves 0.80 hm2/h. Meanwhile, the potato obvious rate, injury rate, skin-damaged rate and reliability are 97.40%, 1.85%, 1.83% and 95%, respectively. Compared with the traditional model, the potato obvious rate of the designed model increased by 6.23 per cent, the potato injury rate decreased by 4.11 per cent, the skin-damaged rate decreased by 3.11 per cent , and the productivity increased by 0.19 hm2/h. 4UGS2 is characterized by its stable and reliable work, efficient operation and higher production. This study can provide effective reference for the development of intelligent technology employed in similar harvesting machinery.