Contact Model Of Spherical Elastic Bodies

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Abstract

As a part of an international project, initiated by the European Union, which involves in building an autonomous machine to harvest fruit and vegetables, a demand for this project was made. This project’s goals are to find the mechanical properties of a material, and performing experiments that test the validity of an analytical model which describes the mathematical connections of movements to forces between spherical elastic bodies. The project dealt with a number of disciplines, beginning with finding standards and methods, through ordering, manufacturing and user interface writing, to experiment performing on a system which was built


in order to validate the model. We chose to model the material as Quasi-Rigid, i.e. deformation occurs only around the contact point. Assisted by new devices that perform tests in a non-destructive method, we carried out tests, which were needed to verify the spatial contact model as developed by Prof. David Elata, in a goal to implement it in the mother project and promoting it to completing its objectives.

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This project involves Development & Construction of a system which is able to assess the forces aplied on a semisphere body subjected to movements upon its surface. Using a 3D precision stage configure against 6-Axis Load Gauge connected to a sample, all controlled by a software build specifically for this use, we were able to perform experiments that test the validity of the model.

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In order to use the mathematical model, the material's mechanical properties, must be implemented to it's equations. These were measured with an Un-Destructive-Testing metod using ultrasound waves, And with the same 3D stage sustem to assess the friction coefficient between the contact materials.

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This project was led by fourth year B.Sc student - Alon Miller and was supevised by Phd - Amir Shapiro, and PhD student - Alon Ohev Zion at The Robotics Laboratory in the Mechanical Engineering Dept' at Ben Gurion University of the Negev. IL.