Feasibility and influencing factors of laser cutting of tomato peduncles for robotic harvesting

Abstract

Due to the dissatisfactory effect of fruit detaching methods in robotic fruit harvesting, the laser may now be a new method to cut off the peduncle. In this paper, the feasibility of cutting tomato peduncles with 30 W, 980 nm fiber-coupled semiconductor laser was firstly verified by tests and calculations. The maximum power density of focusing spot and the depth of focus (DOF) were 4.95 W/mm2and 8.4 mm, respectively, so this laser was able to cut through a peduncle even under large position and angle errors between the focus lens and the peduncle in view of its lower burning temperature, smaller diameter, rougher surface and lower thermal conductivity. It was also found that the drilling through time was linearly correlated with the diameter of peduncle, negative correlated with the laser power and incident angle, binomial correlated with defocusing distance, respectively. The high-success-rate, high efficiency and energy-saving laser cutting can be achieved by adopting better quality or higher power laser and optimization of defocusing distance and incident angle in practical operation of robotic harvesting. Key words: Feasibility, influencing factor, laser cutting, peduncle, harvesting robot.