Study the Parametric Effect of Pulling Pattern on Cherry Tomato Harvesting Using RSM-BBD Techniques

Detachment of fruit from the plants with separation force is important in robotic harvesting. Compared with twisting pattern and bending pattern, the pulling pattern for cherry tomato harvesting is more simple, more flexible, and easier to implement in robotic harvesting. It was found that the detachment force is closely related to the location of the fruit separation. However, in the pulling pattern, analysis of the effect of harvesting parameters of cherry tomatoes at the calyx/fruit joint has still not been carried out in depth. In this paper, the goal of this research was to investigate the effect of different harvesting parameters on the minimal detachment force of cherry tomatoes at the calyx/fruit joint. Experiments were designed according to response surface methodology Box–Behnken design by maintaining three levels of three process parameters—grasping angle, horizontal angle, and pitching angle. Results showed that the pitching angle is the most important parameter, and the grasping angle has little effect on the detachment force, and the detachment force was found within the range of 0.58 N to 2.46 N. Results also revealed that the minimum separation force of the cherry tomato harvesting at the calyx/fruit joint was obtained by the optimum conditions of the grasping angle of 68°, the horizontal angle of 135° and the pitching angle of 0°. Moreover, desirability function has also been used to optimize the angle parameters. The confirmation experiments validate the reliability and capability of the developed model.