2.5.2. Evaluation Indicators

Referring to the index requirements in NY/T648-2015 "Technical specification for quality evaluation of potato harvesters" [24] issued by the Ministry of Agriculture of the People's Republic of China, the loss rate and woundedness rate were selected as the evaluation indexes of the spring-finger picking device.

**Figure 16.** Laboratory test procedure.

(1) Original wounded potato rate: all test potatoes are weighed before the picking operation begins, from which the wounded potatoes are identified and weighed, and the weight of the wounded potatoes in the test area is calculated as a percentage of the total weight of potatoes in the test area, the value of which is the original wounded potato rate calculated according to Equation (10):

$$L\_1 = \frac{Q\_1}{Q} \times 100\% \tag{10}$$

where *L*<sup>1</sup> is the original wounded potato rate, %; *Q*<sup>1</sup> is the original wounded potato quality, kg; and *Q* is the total potato mass, kg.

(2) Loss rate: after operating the picking device, collect the potatoes that were picked up by the machine and the potatoes missed in the test area and weigh them separately. Calculate the percentage of missed potatoes in the test area to the total potato weight (potatoes picked up by the machine and missed potatoes), and take the value as the loss rate, calculated according to formula (11):

$$L\_2 = \frac{Q\_2}{Q\_2 + Q\_3} \times 100\% \tag{11}$$

where *L*<sup>2</sup> is the loss rate, %; *Q*<sup>2</sup> is the mass of missed potatoes, kg; and *Q*<sup>3</sup> is the mass of potatoes picked up by the machine, kg.

(3) Wounded rate: after the device has completed its picking operation, collect the potatoes in the test area (potatoes in potato boxes and missed potatoes) and weigh them. Then, find the wounded potatoes and weigh them. Calculate the percentage of wounded potatoes to the total potato weight, take the value and subtract the original wounded potato rate to obtain the wounded potato rate, calculated according to formula (12):

$$L\_3 = \frac{Q\_4}{Q\_2 + Q\_3} \times 100\% - L\_1 \tag{12}$$

where *L*<sup>4</sup> is the percentage of wounded potatoes, %, and *Q*<sup>4</sup> is the mass of wounded potatoes, kg.
