**1. Introduction**

The potato is one of the most widely grown crops worldwide due to its high yield and unique nutritional value [1]. In 2015, China categorized the potato as a strategic staple food; under the development process of the national grain growing industry structure adjustment and potato staple food strategy, China's potato planting area and total production have become some of the best in the world. Potatoes are planted all over the country, with both planting area and total production on the increase. Although China's potato planting mechanization level is improving year by year, the potato harvest mechanization level is still very low; the potato machine harvesting rate is less than 50%, which has seriously restricted the development of China's potato industry [2–4]. At present, potato machine harvesting methods can be divided into combined and sectional harvesting according to the differences in the harvesting process. In China, potatoes are generally eaten fresh, for reasons such as dietary structure [5]. Potatoes harvested with combine harvesters have fragile skins, high trash content and are not easily stored for long periods, so potato harvesting in China is still mainly done in sections [6]. It is important to develop efficient and low-loss potato harvesting equipment to meet the customary consumption and harvesting methods of potatoes in China.

In order to solve the problems of manual potato picking with high labour intensity and low production efficiency, researchers have done a lot of research and achieved good

**Citation:** Wang, L.; Liu, F.; Wang, Q.; Zhou, J.; Fan, X.; Li, J.; Zhao, X.; Xie, S. Design of a Spring-Finger Potato Picker and an Experimental Study of Its Picking Performance. *Agriculture* **2023**, *13*, 945. https://doi.org/ 10.3390/agriculture13050945

Academic Editors: Cheng Shen, Zhong Tang and Maohua Xiao

Received: 17 March 2023 Revised: 18 April 2023 Accepted: 22 April 2023 Published: 25 April 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

application results. Shi et al. [7] designed a small potato picker with a 30 kw tractor, using a picking shovel combined with a spring-fingered bar conveyor chain to achieve potato picking, and a potato block lifting device and a potato block collection device to achieve potato soil separation and potato block collection, but the wounded potato rate and the rate of contamination are higher than the relevant national industry standards. Xiao et al. [8] designed a small potato picking and grading harvester, using a roller-type potato secondary grading device to achieve combined potato picking, grading and potato block collection, but the number of grading levels does not meet the actual grading requirements, and the picking efficiency is low. Hu et al. [9] designed an integrated potato picking and grading harvester, using a cam mechanism and a vibration dampening lever of the wheel mechanism to achieve horizontal and vertical vibration of the screening part, thus achieving the purpose of potato two-monopoly picking and three-stage sorting, but the size of the whole machine increased, causing a little problem for the machine's turning and turning around. Liu et al. [10] designed a potato harvester with drum-type separation, using a rotary-driven digging device arranged in a circle, while using a drum sieve-type separation structure to separate the conveying device, but there were certain problems of broken skins and injured potatoes. Wang [11] designed an active turntable potato picking device and developed a picking mechanism test stand to carry out exploratory trials in a digitised soil trough, but there was still a certain amount of potato leakage and soil congestion. Yang et al. [12] designed the 4UJ-1400 potato picker, which used a forced pushing device to lift potatoes at a large angle, with good soil removal effects, but low picking efficiency. Wei et al. [13] designed a crawler self-propelled sorting potato harvester, using crawler self-propelled technology, automatic row digging technology and a combination of screen surface separation and manual assisted sorting to achieve potato harvesting, but there are certain problems of potato leakage and wounded, which has not yet been transformed into a popular product.

This paper addresses the problems of low picking rates and high wounded potato rate in mechanised potato harvesting under sectional harvesting conditions, and designs a spring-finger potato picker, analyses the theoretical calculations of its key components, establishes the kinetic equations of the spring-finger in the picking process, and determines the optimal operating parameters through laboratory test in the hope of reducing the loss and wounded potato rates during sectional potato picking.
