project specification

FlexShapeGripper

A gripper whose working principle is derived from the tongue of a chameleon. The FlexShapeGripper can pick up, gather and set back down several objects with the widest range of shapes in one procedure – without the need for a manual conversion. This is made possible by its water-filled silicone cap, which wraps itself around the items being gripped in a flexible and form-fitting manner. The gripper consists of a double-acting cylinder, of which one chamber is filled with compressed air whilst the second one is permanently filled with water. This second chamber is fitted with elastic silicone moulding, which equates to the chameleon’s tongue.

Specifications

Materialsilicone
Cylinder 1 double-acting cylinder

Overview

The FlexShapeGripper can pick up, gather and set back down several objects with the widest range of shapes in one procedure – without the need for a manual conversion. This is made possible by its water-filled silicone cap, which wraps itself around the items being gripped in a flexible and form-fitting manner. 

The gripper consists of a double-acting cylinder, of which one chamber is filled with compressed air whilst the second one is permanently filled with water. This second chamber is fitted with elastic silicone moulding, which equates to the chameleon’s tongue.
The volume of the two chambers is designed so that the deformation of the silicone part is compensated. The piston, which closely separates the two chambers from each other, is fastened with a thin rod on the inside of the silicone cap.

During the gripping procedure, a handling system guides the gripper across the object so that it touches the article with its silicone cap. The top pressurised chamber is then vented. The piston moves upwards by means of a spring support and the water-filled silicone part pulls itself inwards. Simultaneously, the handling system guides the gripper further across the object. In doing so, the silicone cap wraps itself around the object to be gripped, which can be of any shape, resulting in a tight form fit. The elastic silicone allows a precise adaptation to a wide range of different geometries. The high static friction of the material generates a strong holding force. 

Both the holding and the release mechanism are triggered pneumatically. No additional energy is necessary for the holding process. The yielding quality of the compressible compressed air simplifies the coordination between the handling system and gripper during the grip stage. The force and the deformation of the silicone part can be set very precisely with the aid of a proportional valve. This allows several parts to be gripped at once in a single procedure.

References

A brochure which describes the background of the project, its functionalities, and the team that worked on the project.

https://www.festo.com

Paper describing multiple tests and experiments done with Festo grippers.

C. Basson, G. Bright, A. Walker. - South African Journal of Industrial Engineering, May 2018.

Wevolver 2022