Adaptation of a Small Robot for Paddy Fields to the Water Depth Change Using Variable Legs

Abstract

In this study, the authors conduct an operational test of a small weeding robot in paddy fields, and classify its behavioral incapacitations into two groups. Furthermore, the authors propose a leg structure for overcoming a sudden increase in water depth, one of the main causes of incapacitation. The robot is a two-wheeled vehicle with balance floats in the front and rear of the body, and the proposed structure enables the wheels to reach the ground by deforming the legs holding the wheels (variable-leg). The variable-leg robot is compared with a fixed-leg robot via a water tank experiment. It is verified that the variable-leg model can run at water depths of up to 180 mm, whereas the fixed-leg model can only run at water depths of approximately 80 mm. Furthermore, the variable-leg robot can adapt to dynamically changing water depths, as demonstrated by running over a hole.