Polishing robot: vibrations due to impact
To simulate and correct unwanted behavior
M.L. Postma (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Arnold Heemink – Mentor
Titus Gotthardt – Mentor
M. Möller – Graduation committee member
Jacob van der Woude – Graduation committee member
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Abstract
The specific issue researched in this thesis is correcting some inaccuracies that occur when the robot is polishing
certain shapes. The biggest challenge is to mathematically describe this phenomenon in order to find
an appropriate correction. Since there are a lot of influences in the process (friction, movement, impact, degrees
of freedom) this is very difficult to describe. The main topic of this thesis is therefore the description
and simulation of this problem. The research question defined is: what is causing the jumping of the polishing
tool in specific situations on non-flat surfaces and how can this be prevented?
The problem has multiple challenges due to combining a rotating movement with degrees of freedom in the
lateral movement. The cause that has been found with the simulations is the flexibility in the spindle and
the airbearing of the polishing robot. Together with resultant forces, caused by the rotation of the tool and a
certain angle of elevation of the material, the flexibility causes the tool to jump in all directions. The goal of
these simulations is to acquire data that describes the problem phenomenon. When the realistic data of the
simulation is known a correction method is proposed and first simulated.
The method tested to correct this is a static state feedback where the controller is found by minimizing the
H-infinity norm. The results show that this type of controller and feedback can decrease the jumping to 0-10 %
of the original displacements. This correction is still theoretical, but actual physical solutions can be implemented
to test if it could solve the problem.