## 1 Introduction  
Potato is one of the major sources of nutrition for the global population. Northeast China is the primary production region of potatoes in China. The soil in this area contains many clays, high organic matter and high water content, which are good for potato growth. However, the clay in soil increases the stickiness of soil and causes increased resistance when digging potatoes. The ordinary plane digging shovels are commonly used as potato harvesters in Northeast China. However, the substantial soil adhesion to the potato-digging shovel leads to a significant increase in drag resistance, which greatly increases the energy consumption of the tractor and reduces economic benefits to the farmers because of the clay in soil. Therefore, reducing the soil adhesion and drag during digging potatoes in clay soil is of great importance. For the potato digging shovels, the tillage depth is generally approximately 25 cm. The structural size and shape are generally fixed for a certain potato digger because it is necessary to ensure the working width. Compared with soils in other regions, when harvesting potatoes in clayey soil, the moisture content is generally higher, and the high clay content leads to substantial soil adhesion. Hence, the reason for the resistance is soil adhesion to the digging shovels. Therefore, it would be helpful to design a potato-digging shovel with antiadhesion properties and drag reduction for use in the clayey soil region. Conventional antiadhesion and drag reduction methods primarily include aeration, liquid filling, thermal desorption, vibration [1; 2], electroosmosis, and mechanical and surface modification [3; 4]. These methods can reduce the tillage resistance to some extent. However, due to the problems such as poor wear resistance, complicated processing technology, excessive auxiliary parts and additional energy loss, these methods have encountered difficulties during their application. Bionics is an effective interdisciplinary field that addresses the principles underlying the structure and function of living things in nature and involves the invention of new equipment, tools and technology based on these principles to create useful technologies for production and life. In recent years, scholars have generated many excellent results for various engineering applications, especially for reducing soil tillage, because their bionic structures have the ability to reduce adhesion and friction against the soil [3; 5] conducting a large number of experimental studies to discover that some soil animals are inherently capable of reducing soil adhesion. Soil animals such as dung beetles, earthworms and pangolins, etc. move freely in clayey soil without soil adhesion, due to their special nonsmooth surface structure [5; 6]. [PERSON] et al. [3] designed a bionic nonsmooth plow based on the nonsmooth surface structure of soil animals. The bionic plow with the bionic nonsmooth surface structure could reduce the specific resistance of the plowing operation, improve the soil and cover effect, and significantly improve the economic benefits of the plowing operation. [PERSON] et al. [7] integrated the microconvex structure of shark scales and lotus leaves, and then designed a bionic ridge shovel with antiadhesion properties and reduced resistance. [PERSON] et al. [8] designed a bionic bulldozing plate inspired by the pleated body surface structure of earthworms. [PERSON] et al. [5] and [PERSON] et al. [4] invented the bionic wear-resistant plow blade, subsoil blade, furrow opener and bionic rotary tiller blade according to the drag reduction property of the claws on animals such as the field mouse, mole cricket, dung beetle and mole. Bionic research on pangolin scales is primarily based on the wear resistance of the pangolin scale structure. However, the application research of antiadhesion and reducing resistance is rarely reported [9; 10]. In summary, for the bionic resistance reduction of tillage components, the most commonly used bionic prototype was the rough claw of soil animals [11].