Review of tensairity and its applications in agricultural aviation

In recent years,the unmanned aerial vehicle(UAV)has undergone rapid development in field of agricultural plant protection;however,the payload and max-endurance are bottlenecks that limit its further development.Tensairity is a new structure consisting of a bag filled with low-pressure gas,an upper rigid rod and a lower flexible cable.It puts tension pressure on the whole structure through internal gas pressure,provides continuous support to the upper rigid rod,and that is to say,the tensairity improves the stability of the structure in some way.And also,tensairity is a self-supporting and self-balancing system,which means it is a simple,lightweight structure with small storage volume,strong bearing capacity,and low engineering cost.It also has the advantages of gasbag and BSS(beam string structure).The main objective of this research was to introduce the theoretical basis of tensairity and then discussed its development and applications.Moreover,the advantages and disadvantages of tensairity were summarized,and development prospects of tensairity in agricultural aviation were presented.At last,it can be concluded that tensairity has potentials in agricultural aviation.If tensairity is applied in agricultural UAVs,it will solve the two major problems of payload and max-endurance better,and help promoting the development of agricultural aviation technology in agricultural aviation administration and application.Also,it will help with meeting the aerial application requirements of high efficiency and maximal environmental protection.This research will provide a reference for improving working efficiency and economic benefits of UAVs in agricultural plant protection.

General structure design and field experiment of pneumatic rice direct-seeder

In order to meet the requirement of field direct seeding for super hybrid rice:1-3 seeds per hill,a pneumatic rice direct-seeder with six seeding metering devices was designed.Transmission system of pneumatic rice direct-seeder and seed metering device were analyzed in this study.And the pipeline structure and vortex pump were designed and selected.The pressure distribution of the pipeline was tested.The pressure value of each sub-pipeline under the conditions of different main pipeline pressure value was obtained and the reasons for pressure loss were analyzed.The results showed that the variation coefficient between sub-pipelines was less than 5%.The pipeline pressure could be evenly distributed.Further,the field experiments were carried out on super hybrid rice Peizataifeng using two-factor testing,by which the effects of different negative pressure and different forward speed(namely,rotational speed of suction plate)for seeding precision were studied.It found that:(1)the optimal negative pressure was 2 kPa;(2)under the optimal negative pressure,the probabilities of 1-3 seeds per hill for the direct-seeder were 93.41%,95.47%and 97.50%,respectively,when the forward speed of the direct-seeded was high,medium and low speed;(3)the probability of empty hole was less than 2%,which satisfied the field direct seeding requirements of super hybrid rice.Additionally,hill spacing was measured,and the factors affecting the hill spacing were analyzed.The results showed that the fluctuation of hill spacing in the small range will not affect the seeding effect.In this study,a new type of pneumatic rice direct-seeder was designed.The main working components were tested and analyzed.The best parameters of field work were obtained.It provides the basis for the field application of the pneumatic rice precision seeder.