���Ѳ�ժ�C���˿��ٟo�p���I�о�(Ӣ�İ�) ���x

Chapter 1 History and Present Situations of Robotic Harvesting Technology: A Review 1.1 An Industry of Fresh-Eat Fruits and Vegetables and Its Labor-Cost Harvesting Fruits and vegetables are both daily necessities�� and also they are important economiccrops. According to the statistics�� the global production of total fruits and vegetablesin 2019 reached 8.83 x l08 t and 11.30 x l08 t�� respectively.Globally�� the rate betweenfresh-eat and processed fruits and vegetables is about 7:3.Chinese vegetable and fruitplanting area and output both rank the first in the world�� but the proportion ofprocessing fruits and vegetables is only about 5%. Usually�� it is not necessary for the harvesting of processing fruits and vegetablesto distinguish the ripeness�� and also a certain damage is tolerant in the harvest. Forexample�� tomato fruit can be whole-plant harvested and apple fruit can be harvestedmechanically by vibratory excitation.ln developed countries�� the non-selective mech-anized harvesting of processed fruits and vegetables has been gradually popularized.But for the larger proportion of fresh-eat fruits and vegetables�� the non-selectivemechanized harvesting method cannot adapt to both the individual difference of thefruit maturity and the harsh demand of non-destructive harvest. So far�� it is stilldependent on human labor for selective harvesting. With the gradual mechaniza-tion of the production of fruit and vegetable cultivation�� harvesting has become thelast link to break through the whole process of mechanical operation. According tothe investigation�� the labor consumption of strawberry production in Japan reaches20��000 h/ha [11�� and the harvest takes up about 40% of the totallabor amount [1��2].Meanwhile�� the shortage of agricultural labor and the rising cost oflabor haveseriously affected the development of the fruit and vegetable industry. In China�� inrecent years�� the labor force�� especially the young and middle-aged labor force�� hasalso been rapidly transferred to other industries. In the busy farming season�� the laborshortage has begun to appear in the vast rural areas. The labor intensity of the elderlyand women in rural areas has greatly increased�� and the production efficiency hasdecreased obviously. The contradiction between the rapid development of fruit and vegetable produc-tion�� the shortage of agricultural labor�� and the excessive intensity of labor isbecoming more and more obvious�� and the replacement of complex manual selectiveharvesting can only be realized through the in-depth study of the technology of theharvesting robot. The research and development of fruit and vegetable harvestingrobot are of great significance for reducing the labor intensity of agricultural practi-tioners��liberating the agriculturallabor force andimproving the intensive productionlevel of fruits and vegetables. 1.2 The History and Current Situation of the Development of Robotic Harvesting Equipment in the Whole World A typical harvesting robot for fruits or vegetables is usually composed of mobileplatform�� manipulator�� end-effector�� vision system�� and control system. Since fruitand vegetable species and varieties�� and cultivation patterns are all numerous andcomplicated�� various kinds of harvesting robots and their end-effectors have beendeveloped at home and abroad. The action principle�� structure form�� complexity��operation effect�� and performance also have a very big difference. 1.2.1 Tomato Harvesting Robots 1. Fresh-eat tomato and its robotic harvesting problem As a favorite fresh-eat vegetable�� its robotic harvesting has been paid much attentionby researchers worldwide. Concerned research has been camed out continuously formany years�� and a series of achievements have been produced. At the same time�� the tomato is also one of the fruits and vegetables that are mostdifficult to be harvested by robots. At present�� in the face of fresh food�� commontomato fruits are usually picked as single fruit one by one�� while cherry-tomatofruit is usually picked in clusters. Compared with cucumber�� eggplant�� apple�� andother fruits and vegetables�� there is usually 3-5 tomato fruit in one cluster. Theygrow densely and touch each other�� and the difference of fruit-stem posture is moresignificant (Fig. 1.1). The great difference of growth posture and distribution posesa greater challenge to the implementation ofintelligent robotic harvesting: (1) Recognition of the target fruit The close and occlusion of the fruit are more serious. For the vision system of theharvesting robot�� although the color difference between mature tomato fruit andleaves is distinct�� it is difficult to identify and locate the target fruit since multiplefruit images are integrated into one or even completely overlapped to be difficult tobe segmented [3�� 4]. Fig. 1.1 Difference of growth posture and distribution among the fruit of tomato�� cucumber�� and Eggplant (a) Tomato (b) Cucumber (c) Eggplan