A Gripper for Deformable and Delicate Objects at High Acceleration Using a Contact-Reactive Grasping Approach

A Gripper for Deformable and Delicate Objects at High Acceleration Using a Contact-Reactive Grasping Approach

Heeringa, Willem (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Biomechanical Engineering)

Smit, G. (mentor)
Della Santina, C. (mentor)
Dodou, D. (graduation committee)

Delft University of Technology

Biomedical Engineering

2021-11-25

Introduction: This research aims to develop a gripper that is capable of handling deformable and delicate objects at high acceleration (≥10 G) using a contact-reactive grasping approach while moving. Commercial grippers are already suitable for handling various food products at high speed and acceleration when combined with a parallel manipulator, but use a standard grasping approach. The gripper is positioned over the object and moves down to grasp it requiring (in most cases vision based) 2D positioning. Contact-reactive grasping can overcome the need for costly high accuracy vision systems and reduce stationary time taken up by vertical movement.
Methods: The working principles and design aspects of a variety of soft grippers were analysed. Requirements were set up from the analysed soft grippers, defining the boundaries of the concepts. Concepts have emerged from these requirements, and the most promising concept has been developed towards a final design. From the final design a working prototype emerged, the FinFix gripper. The FinFix gripper consists of two fixed fingers and two movable fingers. The fixed fingers are equipped with flex sensors to detect contact with the object while approaching the object horizontally. The two movable fingers are individually actuated by pneumatic pistons. 3D-printing was mostly used to manufacture the FinFix gripper. Static as well as dynamic grasping and holding tests were conducted to verify if the functional requirements were met.
Results: The FinFix gripper has soft contact with the object to prevent bruising or denting. The test results show that the gripper can hold an apple, a tomato and an egg at 10 G of lateral acceleration. The gripper is also able to hold an object with a size of at least 70mm and has a total weight 537 grams. A full grasping cycle only takes 1.01 seconds from the start of movement until the object is released when the distance between pick and place location is around 400 mm. This gripper uses already existing contact-reactive grasping to detect contact with the object and reduces the positioning requirements to one dimensional. The way contact-reactive grasping is used makes this design stand out from other contact-reactive grasping implementations.
Conclusion: By developing the FinFix gripper, new knowledge was acquired on how contactreactive grasping can be used in fast pick-and-place operations for deformable or delicate objects. Future research is recommended to increase food contact safety, holding performance and sensing performance. The gripper’s performance showed excellent potential to be further developed into a possible commercial product.

Pick-and-Place
high-speed
Gripper
Deformable
Delicate
Contact-reactive

http://resolver.tudelft.nl/uuid:7a18fc28-753a-41ae-b4bf-0b277998d8a1

2023-11-25

Student theses

master thesis

© 2021 Willem Heeringa