间歇式自动取样条播排种器排种性能检测试验台研制

Development of testbed for seeding performance test of drill metering device based on intermittent automatic sampling

针对条播作物排种器进行室内台架性能检测时,人工检测播种均匀性费时费力、自动化检测手段缺乏等问题,该文设计了一种条播排种器排种性能检测试验台,利用间歇式自动取样机构,实现定时定距自动化取样及排种均匀性检测。其工作原理是种子落入传送带上形成种子带,随传送带一起前进,当运动至取样板处时,气泵驱动取样板以均匀的速度往复运动,将特定距离的种子带推离出种带,并分散成弧形,采用数码照相机获取样本种子图像,利用Matlab图像处理技术,获取样本种子数量,判断所测试排种器的排种性能。采用单片机控制排种轴转速、取样板的启停及运动方向,并通过上位机显示。对试验台关键结构和参数进行设计,确定种带宽度为30 mm,护种板长度150 mm,与传送带之间距离控制在2~3 mm。为减少种子堆叠和黏连,保证样本种子带均匀排列,易于后期图像处理,设计了"一"、"T"和"工"字型3种结构的取样板,通过种子受力与运动规律分析,确定"T"型取样板为最优结构,取样长度L为40 mm。以外槽轮排种器播种小麦为研究对象,使用Design-Expert软件进行中心旋转组合设计试验,结果表明,传送带驱动电机转速分别为20、28.79和28.79 r/min时,样本种子堆叠率分别为100%、92.34%和75.21%;排种量6 g/s时,样本种子堆叠率最高,为40.15%。与人工定距取样检测方法的对比试验结果表明,间歇取样检测法利用图像批量处理获取样本种子数量的时间约为5 s;而人工定距测试的平均耗时为1 min,而且样本数量越多,耗时越长。试验结果表明,间歇式自动取样的条播排种器排种性能检测试验台设计合理,能够大大提高排种器排种性能检测效率,可为条播作物的排种器排种性能检测试验台的优化设计提供参考。

Aiming at the problems of manual test of performance test of drill seed metering uniformity, such as time consuming and laborious, lack of automatic test means and so on, a testbed for drill seed metering performance test was designed. With the intermittent sampling mechanism, the testbed can realize automatic sampling and sowing uniformity detection at fixed intervals. Its working principle is that the seeds falling onto the conveyor belt and moving along with the conveyor belt to form the seed zoon, when the seed zoon moving into the sampling zones, a part of seeds were pushed to the outside of seed zoon by sampling plate, which has a reciprocating motion driven by the air pump, the seeds outside the seed zoon were scattered into an arc under the thrust force of sampling plate and formed the sampled seeds. The distribution of sampled seeds were imaged by the digital camera, and then the numbers of sampled seeds were obtained by image processing technology using Matlab software, which was used to evaluate the seed metering uniformity of seed metering device. Single chip microcomputer was used to control the rotary speed of seeding shaft, start and stop of sampling plate and its movement direction and the result was displayed on upper computer. The key structure and parameters of the testbed were designed, and the seed zoon width was determined to be 30 mm, the seed guard plate length was 150 mm, and the distance between the seed guard plate and the conveyor belt was controlled to be 2-3 mm. To reduce the stacking and adhesion of seeds, ensure the uniform arrangement of sampling seed zoon, and facilitate the image processing in the later stage, three sampling plates with the shape of "一", "T" and "工" were designed. Based on the analysis of the force and motion of the seeds, it was determined that "T" shape sample plate was the optimal structure, and the sampling length was 40 mm. The wheat seed metering device with external trays was used as the research object, and the center combined rotation design test was carried out with Design-Expert software. The results showed that when the rotary speed of conveyor belts driving motor was 20, 28.79(seed rate was 5.41 g/s) and 28.79 r/min(seed rate was 3.41 g/s), the stack rate of sample seeds was 100%、92.34% and 75.21%, separately;when the metering quantity was 6 g/s, the stack rate of sampled seed was 40.15%, and there was less stack in other treatments. Compared with the manual distance sampling, the time consuming of the intermittent automatic sampling method was about 5 s, but that of the manual distance sampling was about 1 min, and the time increased with the increase of sample seeds number, which made the time difference larger. The result illustrated that testbed for seeding performance test of drill crop based on intermittent automatic sampling was reasonable, which could improve the working efficiency.