A mechatronic system for automated topping and suckering of tobacco plants

Abstract In agricultural crops, such as tobacco, the budding part of the plant is removed (topping) and the growth of axillary shoots (called suckers) is controlled with chemicals in order to produce good quality heavy-bodied darker tobacco leaves. Nowadays, topping and suckering are largely performed by hand and as a result the application process is time consuming. In this study, the design and implementation of a novel mechatronic system is presented, whereby the topping and suckering treatments can be performed automatically. The mechatronic system and its auxiliary equipment were mounted on a three-wheeled mobile platform. The novel system includes a topper unit, a high-precision sprayer, and a bifurcated metal guide designed to keep the plants in an upright position. An infrared beam sensor is mounted below the circular saw blade to locate the plant stalk and trigger a pulse so that the high-precision sprayer applies the proper amount of suckercide to the tobacco stalk. The high-precision sprayer travels parallel to and over the tobacco plant rows with a speed that matches the ground speed of the wheeled mobile platform. This is achieved by the use of a built-in drive wheel encoder. The mechatronic system was tested in both laboratory and field conditions. In the tests carried out, the travel speed of the three-wheeled platform was kept between 0.1 and 0.5 m/s. The topping and suckering of five tobacco plants lasted approximately 20 s. Traditional application has a disadvantage over the mechatronic system in that each worker is independent of the others and the speed of the whole process is essentially determined by the slower worker. In future work, the mechatronic system can be integrated into a small autonomous wheeled platform, a drone, or can be mounted on the horizontal boom of a suitably modified trailer sprayer.