Colloquia

Summary

The increasing demand for automation in the horticultural sector underscores the necessity for grippers capable of handling objects with varying sizes and shapes without causing damage. This study focuses on optimizing a passive, underactuated, flexure-based gripper to minimize the force distribution for different object geometries. The optimization process considers the balance between the geometry and the moments induced by flexure joints to reduce the effective stiffness between the gripper and the object. A simplified analytical model is employed to explain this balancing method. The infinity norm of the effective stiffness matrix is minimized and serves as the objective function in the optimization. Drawing from literature on size and shape variations of red delicious apples, the gripper is designed to maintain contact forces within a range of 13.65 to 15.35 N, accommodating size and shape variations of $\pm$ 10 \% of the nominal radius at all contact points. An experimental test setup is constructed to validate the design process, featuring an adjustable object to measure contact forces across varying object sizes and shapes. The worst-case forces observed in the experiments are 13.6 and 15.5 N, thereby validating the design approach.