Towards Pneumatic Spiral Grippers: Modeling and Design Considerations

Area of Science:

• Robotics and Mechanical Engineering
• Soft Robotics
• Actuator Design

Background:

• Nature demonstrates spiral grasping for stable manipulation of long, slender objects.
• Pneumatic fiber-reinforced actuators offer compliant and adaptable gripping solutions.
• Accurate modeling is crucial for designing effective continuum robotic grippers.

Purpose of the Study:

• To investigate the design and modeling of spiral grippers actuated by pneumatic fiber-reinforced materials.
• To develop and compare reduced-order models for predicting gripper deformation under self-weight.
• To establish a systematic design framework for spiral grippers adaptable to various object sizes.

Main Methods:

• Development of two reduced-order models: a pure helical model and a spatial Cosserat rod model.
• Analysis of gripper deformation mechanics considering fiber reinforcement and actuator self-weight.
• Experimental validation using two distinct gripper prototypes and a range of slender objects.

Main Results:

• The spatial Cosserat rod model achieved high accuracy (less than 8% deviation) for gripper deformation.
• The pure helical model showed significant deviations (over 40%) for longer actuators (>200 mm).
• Successful experimental gripping of objects ranging from 20 mm to 60 mm in diameter was demonstrated.

Conclusions:

• The spatial Cosserat rod model provides a robust framework for designing spiral grippers.
• Gripper deformation correlates with the number of spiral turns, directly impacting grip quality.
• The proposed systematic design approach enables effective handling of diverse slender objects.