## 1 Introduction  
With the economic development and the consumption upgrade, urban and rural residents have increasingly diversified food demands. Pickled vegetables are commonly flavored non-staple foods with a yield of 6.50 million tons annually in China [1, 2]. These minimally processed foods, such as pickled cucumber chilli sauce, are fresh, crisp, hot, and sour while maintaining the same nutritional and organoletic (sensory) quality of fresh vegetables [3]. So pickled vegetables are considered one of the important agricultural by-products of the Chinese diet, without which any meal is imperfect. In recent years, dehydrated vegetables have been increasingly widely used in convenience foods, desserts, breads, conditions, snack foods and other scenes with the progress of dehydration technology and the acceleration of residents' life pace [4]. Some supermarkets in large and medium-sized cities and remote areas also have a large demand for dehydrated vegetables. The use of processed methods to transform plant-derived foods into ready-to-eat products may differ in thousands of ways for various pickles and dehydrated vegetables. But their raw materials are mainly fresh vegetables. The efficient facility agriculture is the basis to ensure the yield and marketability of stubble vegetables, which greatly supports the development of vegetable agriculture and sideline product processing [5]. So, it is significant to develop modern greenhouse agriculture, which can supply various nutritious foods regardless of seasons. Plug trays are actively used to grow seedlings, which can well adapt to further growth and development after transplantation. Their other advantages are uniform plant quality, effective production scheduling, and efficient materials handling. According to the statistics, 350 billion plants of professional plug seedlings are produced annually in China [6]. Before reaching the consumers, these seedlings will be transplanted to individual pots of growing flats for further growth and may be handled many times [7; 8]. Manual transplanting in large-scale production might be labor-intensive and less uniform than mechanical operation [9; 10]. It is also expensive and time-consuming. The mechanized transplanting technology has a high seedling preservation rate and a fast growth process, which can significantly contribute to agri-food waste mitigation at the farm level. The use of robots in the greenhouse has been suggested to carry out these repetitive and burdensome tasks in an accurate and reliable way [11]. The labour shortage has also made greenhouse producers seek help from mechanized efficient production of raw materials for these ready-to-eat products [12]. Much research on automated transplanting systems has been made worldwide, which wants to develop effective processing methods for seedling transplanting with less damage [13; 14; 15; 16]. Relying on the advanced industrial robot technology, the developed countries in Europe and America began research on developing fully automatic transplanters for greenhouse plants several years ago. A robot was studied to transplant bedding plants with computer graphics and simulation [17]. The testing results showed that the robot could transplant most seedlings in the low damage condition at an average cycle time of 3.3 min for one 36-cell growing flat. Despite being inefficient, this study demonstrates that it is feasible to use robots for automatic transplanting. Many mechanical and horticultural factors were also checked to understand their influences on the transplanting quality [18]. These studies provide the design basis for further development of dedicated devices. An automatic robotic transplanting system was designed and evaluated for bedding plants, such as cucumber (_Cucumis sativus_ L.), tomato (_Solanum lycopersicum_ L.), and other varieties [7]. Further, some tests showed that the robotic transplanting performance was affected by the accuracy of different end-effector positioning and the seedling conditions.