Planning experiment device for validation of holding quasi-rigid bodies model

From BGU Robotics Lab
Jump to: navigation, search


Summary: This project is a part of a vast project of the European Union, Which deals with an autonomic system for fruit picking. The essence of the project is construction of an experimental verification system that confirms the grip model theory, which describes the forces acting on the fruit as it is being picked. Because of its scope, this project continues a previous project that began last year. The grip model is based on a contact model, which describes the relationship between the shifts of forces between the two bodies, for flexible materials defined as Quasi-Rigid. The project carried out a thorough literature study on flexible bodies and mechanical grippers, topics which we rarely have been learned during our university degree. Being a continuing project with most of the designing was not made by us, the main difficulty that faced us was to adapt the state of mind from the point where further work was paused. Due to accuracy requirements and complexity this project deals many design challenges. Challenges that some of them found solutions before they discovered and some found solutions while working on the project. To achieve a level of results that consistent with the theory it requires precise system components, thus the project has a high budget to tens of thousands of dollars. The experimental system is based on robotic gripper that holds the object who serves as the fruit. Accordingly, there is a stretch system, which simulates the branch holding the fruit. During the project we used a variety of tools that available for us for the assembly, including ordering a third-party structured part, parts that manufactured with three – dimensional printer, producing parts in the university workshop and parts manufactured by ourselves. At the same time, we built a user interface designed to control most of the elements of the system using a computer. Our experimental results shows that the system reflects consistently and faithfully the forces exerted on the object.

File:Element with patch.jpg The element used in the expirament as a fruit. Using the robot.jpg The expirament system at work

File:Graphs.jpg The first expirament results. Each set of lines (Red, Green, Blue) represents one expirament. All 3 expiraments were made under the same geomtry.

The gripper demonstrates its abilities.

One of our expiraments. Side pulling of the object.

It is advised by PhD student - Alon Ohev Zion

And led by fourth year B.Sc students - Dolev Sebag & Shahar Lapid