Development of transplanting manipulator for hydroponic leafy vegetables

The production of hydroponic leafy vegetable plug-seedlings uses coco-peat as culture substrate in South China.Coco-peat has lowered density than peat-moss,and the friction between substrate block and pickup tool is small.So,it is hard to pick up in mechanism transplantation.In order to increase the friction,the existing transplanting manipulator had relatively complex structures.To simplify the structure of transplanting manipulator and improve the stability of picking up substrate block,four stainless steel fingers with rectangular cross-section were used in this research.A vertical driving was used to realize the coupling effect that could insert and shrink at the same time,by applying different combination of constraints to the steel fingers.This could increase friction between the steel fingers and the substrate block,and then enhance the stability of the substrate block.Different combinations of constraints were applied to the rectangular stainless steel fingers(3 mm×0.8 mm).The working videos of steel fingers were taken by high-speed photography.High-speed motioned analysis software was used to acquire and analyze traces of steel fingers movements.When the length which top end of the steel fingers moved outward(M)is equal to 1.5 mm,the length which guiding part widened(N)is equal to 1 mm,the shrinking distance of steel fingers is 4.2 mm.In this research,16-day hydroponic leafy vegetable plug-seedlings were used for performance,which cultivated with coco-peat substrate with the moisture in the substrate at 81%.The transplanting manipulator was attached to a Denso robotic arm to conduct transplanting performance test.When the shrinking distance of steel fingers increased from 0 mm to 3.2 mm and the inserting angle decreased from 80°to 77°,the lifting force of substrate block increased by 118%from 1.45 N to 3.16 N.However,excessive shrinkage stirred the substrate block,which would reduce the friction between the substrate block and pickup parts and lowered the lifting force of pickup part in the substrate block.The experimental results also demonstrated that when the shrinking distance of the steel fingers reached 3.2 mm and the root distribution rate reached 46%,the success rate of transplantation was 80%.When the leafy vegetable plug-seedlings root distribution rate reached 92%,the success rate of transplantation was 96.67%.The degree of root distribution rate was positively correlated with the transplantation success rate.Therefore,in order to ensure an acceptable success rate of transplantation,the root distribution rate of leafy vegetable plug-seedlings should be at least 90%.This study provides a technical reference for developing simplified transplanting manipulator that can be used to transplant the hydroponic leafy vegetable plug-seedlings with coco-peat as the culture substrate.

Development of a high-productivity grafting robot for Solanaceae

Grafting is a green,environmentally friendly,and sustainable way to prevent soil-borne diseases.Although artificial grafting is the main grafting approach used for grafting production,it has some problems which are low productivity,unstable operating quality and labor-intensive.Hence,some countries have been engaged in the development of grafting robots for the past two decades;however,the productivity of these grafting robots has no advantage when compared to artificial grafting.This study aims to develop a high-productivity grafting robot(HPR)for Solanaceae.To improve grafting productivity,this paper adopted plug trays to feed crown-removed rootstocks automatically and carried out multi-plant simultaneous grafting to improve grafting productivity and extensibility.Manipulators were employed to take out rootstocks,increase the distance between them,and transfer them to transfer cups for the simultaneous multi-plant grafting.At the same time,negative pressure mechanisms were designed for speeding up the auxiliary feeding of root-removed scions.Although the HPR was designed in a two-operator mode,a one-operator mode can also be implemented by adjusting the control program.Tests were conducted by varying the artificial feeding speed to analyze the performance of the grafting robot.The results showed that the productivity of the robot in the two-operator mode was 2250 plants/h,and 1542 plants/h in one-operator mode;comparing the artificial feeding productivity with auto grafting productivity,it was found that the capacity of the grafting robot was higher than the feeding speed of the one-operator mode but lower than that of the two-operator mode.