Shading compensation methods for robots to harvest strawberries in tabletop culture

A strawberry robot with five degree of freedom was developed. Improvements and developments are based on the past experimental results. In order to avoid the aging of light source and heating of the system LED was used for illumination. However, because of geometrical constrains and inherited characteristics of LED, non uniform illumination exists in the system. Present study compares the impact of illumination intensity correction on the strawberries area detection. Two illumination correction methods are compared in this study, first method is based on the shading reference and second method is based on L*a*b*. Actually, light intensity variation is non linear with the increasing depth, however it becomes almost linear after shading correction. Furthermore strawberry is far from the light source therefore intensity variation on the strawberry surface is a flat curve, it is almost a flat plane. The curvature of strawberry is steep, as strawberry is far from the light source illumination variation after shading is almost negligible. Future study is required to understand the influence of intensity correction on the fruit maturity calculation.