土下作物自动对行挖掘收获试验台研制

为了提高土下作物机械化收获质量和效率,解决土下作物收获机械田间试验成本高、效率低、数据采集不便且受天气因素影响大等问题,该研究设计了一种土下作物机械收获自动对行挖掘试验台。该试验台主要由传动装置、速度调节装置、偏离行中心距调节装置、块根固定及株距调节装置、偏离探测装置、液压纠偏执行机构和挖掘模拟装置以及测控系统和液压系统组成。在分析试验台工作原理的基础上,进行了关键部件的结构设计及参数确定,设计了集成角度传感器、位移传感器、速度传感器的机电液一体化测控系统。以甜菜收获为研究对象,以株距、偏离行中心距离和前进速度为试验因素,以漏挖率为指标进行试验台准确性田间对比正交试验。试验结果表明,在不同前进速度、偏离行中心距离、株距等参数组合下,试验台试验漏挖率为2.33%~2.72%,田间试验漏挖率为2.38%~2.92%。与田间试验相比,漏挖率绝对偏差率范围为2.10%~6.85%,平均偏差率为3.67%,且漏挖率越大,偏差率越大,试验台具有较好的准确性。该研究可为甜菜、萝卜、土豆等土下作物的自动对行挖掘收获系统设计提供参考。

Development of the test bench for automatic alignment digging harvest of subterranean crops

In order to improve the quality and efficiency of the mechanical harvest of crops under soil, and to solve the problems of high cost, low efficiency, inconvenient data collection and greatly affected by weather on the field test of harvest machines for crops under soil in China, an automatic alignment digging harvest test bench for crops under soil harvesting is designed in this paper. The test bench is mainly composed of a transmission device, speed adjustment device, off-centerline distance adjustment device, root fixed and plant spacing adjustment device, deviation detection device, hydraulic correction actuator and digging simulation device, measurement control system and hydraulic system. The overall structure and working principle of the test bench are briefly analyzed, and the structural design and parameter analysis of key components are especially introduced. A gantry with adjustable front and back distance and height between the deviation detection device and the digging simulation device is designed. Using four-bar linkage, a deviation detection device is designed to detect the distribution of crop under soil in the soil and transfer it to the controller. An digging simulation device with resistance is designed to simulate the soil resistance of the digging device during the process of digging and harvesting. A device with root fixed, plant spacing and off-centerline distance adjustment is designed to simulate the actual plant spacing, off-centerline distance and other growth conditions in the field. The mathematical relationship between the expansion and contraction of the hydraulic cylinder and the moving distance of the digging mechanism is established. The hardware of the measurement and control system is mainly composed of control box, computer, pressure sensor, flow sensor, displacement sensor, speed sensor, hydraulic solenoid valve, hydraulic cylinder and high-speed camera. The software adopts the fixed dual-threshold dead-zone PD control algorithm. In order to improve the generality of the test bench, it is only to replace the original detecting rod with ridge shaped detecting rod and detecting wheel, and replace the root fixing device with ridge shaped simulating adjusting device when the peanut, potato and other crops completely buried in the soil are dug. Taking the beet harvest as the research object, the plant spacing, off-centerline distance and forward speed as the experimental factors, and the missed digging rate as the index, the comparative tests between the test bentch and field operation was carried out. The test results showed that the leakage rate of the test bentch is 2.33%-2.72%, and the leakage rate of the field test is 2.38%-2.92%. The test bentch has good excavation accuracy, the absolute deviation rate range is 2.10%-6.85%, the average deviation rate is 3.67%, and the larger the leakage rate is, the larger the deviation rate is. This study can provide reference for the design of automatic alignment digging harvest system of underground crops such as beet, radish, potato, etc.