Infield pre-sorting is intended to remove processing-grade (inferior) fruit that are not suitable for the fresh market, so that growers can handle sorted apples differentially in postharvest storage and packing to achieve cost savings. To achieve this goal, we developed an apple infield grading and sorting system, in which fruit singulation, rotation, and transportation are achieved by using simple, compact pitch-variable screw conveyors, fruit grading (for size and color) is accomplished with a low-cost imaging system, and fruit sorting is done by using paddle sorters. Experiments were conducted for ‘Red Delicious’ and ‘Golden Delicious’ apples to evaluate the overall performance of the infield grading and sorting system in terms of grading repeatability (i.e., chances of each apple that would be graded into the same quality grade in multiple runs and different lanes), bruising damage, and sorting accuracy (consistency between the imaging-based grading results and destinations). Results showed that the grading repeatability rates of the system were above 90 % and 81 % for intra- and inter-lane grading, respectively. The system achieved above 99 % sorting accuracy for the system throughputs of 7.5, 9.0, and 10.5 fruit s⁻¹, while 100 % of sorted apples were graded Extra Fancy and 55 % or higher of the apples incurred no bruising damage during the grading and sorting process. The infield grading and sorting system is compact and robust in performance, and it can meet commercial infield sorting needs.

现场预分拣旨在去除不适合新鲜市场的加工级（劣等）水果，以便种植者可以在收获后的存储和包装中以不同的方式处理分拣的苹果，以节省成本。为实现这一目标，我们开发了一个苹果内地分级和分拣系统，该系统通过使用简单，紧凑的可变螺距螺旋输送机来实现水果的单颗化，旋转和运输，而水果的分级（尺寸和颜色）较低成本的成像系统，并使用桨式分拣机对水果进行分拣。针对“ Red Delicious”和“ Golden Delicious”苹果进行了实验，以评估分级重复性（即，每个苹果在多次运行和不同车道上被评级为相同质量等级的机会），瘀伤损害和分选准确性（基于成像的分级结果与目的地之间的一致性）。结果表明，车道内和车道间分级的系统分级重复率分别高于90％和81％。对于7.5、9.0和10.5个水果的系统吞吐量，该系统实现了99％以上的分拣精度^-1，而100％的已分类苹果被定为“特级花梢”，并且55％或更高的苹果在定级和分类过程中未遭受瘀伤损害。现场分级和分拣系统结构紧凑，性能强大，可以满足商业现场分拣的需求。