# Current Status and Future Directions for Combined Tillage and Sowing Technology and Equipment
## 4 Research on Precision Sowing Technology
### Seed Guiding Technology and Device  
As an important component of precision sowing technology, numerous studies have been conducted to study the transport mechanism of the seed guiding devices from related technical studies and devices, and to continuously improve its stability and precision through form innovation, structural optimization, and other means, in order to further improve the operational performance of the precision seed metering device. Examples include those based on mechanical principles which have developed supporting precision planter seed guiding parts for form innovation. [PERSON] launched a 2015 series brush belt seed guide device, making the use of the brush belt speed adjustable, to solve the problem of seed falling into the seed groove under the high-speed operation of the planter, bouncing and rolling, and other problems, and to achieve zero-speed seed casting; its structure is shown in Figure 15[103]. [PERSON] designed a belt seed guide device, which improves seeding accuracy by reducing the height of seed casting. The seed guide device fixed on the seed discharge frame is driven by the discharge shaft, and the seeds are transported to the furrow under the constraint of the seed guide belt [104]. Precision Planting has introduced the Speed Tube model conveyorized seed guide. The device utilizes a single pair of toggle fingers to throw the seed onto the conveyor belt, and then finally, under the operation of the conveyor belt, the seed is delivered to the seedbed. The speed of the conveyor belt is adjustable to accommodate different operating speeds for optimal operation [105]. [PERSON] designed a toggle finger synchronous belt-type seed guiding device, which uses the seed pushing plate to push the seed to the seed guiding device in the seed delivery cavity, and  
Figure 14: Multi-branch convergence pipe geometry. under the action of the toggle finger synchronous belt and related structures, realizes the controllable displacement trajectory of the seed movement, and improves the accuracy of seed casting under high-speed operation [106]. The belt seed guiding device constrains the trajectory of the seed, reduces the collision deviation in the displacement process, reduces the bouncing and rolling that falls into the furrow, and realizes an orderly and uniform seeding process. There are also studies that optimize and improve the key components of the seed guide link by optimizing parameters such as the curve and structure of the seed guide tube. The Horsch company developed a MAESTRO SW-type air-seeder which supports the seed guide tube through the use of an inclined curve-type structure, and the seed guide tube as a whole for the upper wide and lower narrow form, to avoid the seed colliding violently within the seed guide tube [107]. [PERSON] et al. used the zero-speed seeding principle to change the straight line-type seeding tube to a straight line-type combined circular arc-type seeding tube, and applied the zero speed seeding theory to achieve uniform and stable seeding under the high-speed operation of the 2 BQ-28 Precision Seeder [108]. ENDERUD explored the change law of the energy consumption of seed movement in the seed guide tube based on mechanical theory, and found that the uniformity of seed placement is best when the angle of the seed guide tube is 60\({}^{\circ}\)[109]. [PERSON] et al. used Geomagic Design software for three-dimensional reverse engineering to optimize the existing seed guide tube by drawing on the structure of high-quality seed guide tubes to reduce the collision between the seeds and the tube wall, and the mesh data of the seed guide tubes and the adjusted pairs are shown in Figure 16[110]. At this stage, the method for improving the performance of the seed guide mainly starts from the two aspects of the movement form and the seed casting trajectory.