An Approximated, Control Affine Model for a Strawberry Field Scouting Robot Considering Wheel–Terrain Interaction

Abstract

SummaryRecently, autonomous field robots have been investigated as a labor-reducing means to scout through commercial strawberry fields for disease detection or fruit harvesting. To achieve accurate over-bed and cross-bed motions, it is preferred to design the motion controller based on a precise dynamic model. Here, a dynamic model is developed for a custom-designed strawberry field robot considering terramechanic wheel–terrain interaction. Different from existing models, a torus geometry is considered for the wheels. In order to obtain a control affine model, the longitudinal force is curve-fitted using a polynomial function of the slip/skid ratio, while the lateral force is curve-fitted using an exponential function of both the slip/skid ratio and slip angle. An extended Kalman filter (EKF) is then developed to estimate the unknown parameters in the approximated model such that the state variables propagated by such a model can match experimental data. The approximated model and the EKF-based parameter estimation method are then validated in a commercial strawberry farm.

A Review of Robots, Perception, and Tasks in Precision Agriculture

“…Cubero et al [125] and Rey et al [126] presented two separate robotic systems for detecting pests and disease on carrot fields and olive trees, respectively. Barbosa et al [127] successfully tested an autonomous robot for monitoring cotton and soy crops; Menendez-Aponte et al [128] suggest a robot for strawberry field scouting, and ByeLab [129][130][131][132] is a robot designed to check plant volume and health in orchards. Commercially accessible robotic platforms have lately been available [133,134].…”

Design and development of a novel autonomous scaled multiwheeled vehicle

“…A kinematics control law that considers wheel yaw, roll, and suspension pitch for a 4WS4WD vehicle is proposed in [11]. Aponte et al [17] designed a dynamic model for a four-wheeled strawberry collecting robot that also analyzed tire soil interactions in addition to testing a physical prototype. Motion control with in-wheel motors is described for a six-wheel drive and six-wheel steer (6WD6WS) vehicle in [18] where vehicle dynamics performance are improved, implementing independent wheel torque and steering control; the results from this work are validated based on simulation.…”