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To ensure that the design method resulted in a functional system, a prototype will be build from the current state of the design. |
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Although the development only implemented a very small portion of the full design, I determined that a prototype is more valuable than repeating the development cycle for the next feature. |
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Although the development resulted in only a partial design, I determined that a prototype is more valuable than repeating the development cycle for the next feature. |
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For the construction of the prototype \ac{ots}-parts are used as much as possible and the mechanical linkages of the SCARA will be printed. |
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To write characters on a whiteboard, drivers and controlloop have to be implemented in software. |
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To write characters on a whiteboard; drivers and controlloop are implemented in software. |
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\subsection{Construction} |
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The construction of the SCARA consists of a 3D printed mechanical structure that is actuated with stepper motors. |
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The type of stepper motor was already chosen during the development of the SCARA. |
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For the mechanical part I used OpenSCAD as CAD software, based on prior experience with the software. |
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As the inverse kinematics were already determined in basic model of the SCARA they could be easily parsed to the CAD software. |
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This allowed me to check for clearance between the mechanical parts, while repeating \autoref{test1}. |
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The test revealed that there was collision between some parts. |
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These collisions were resolved by adding a indentation and moving linkage and are shown in \autoref{fig:scad_clearance} |
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The configuration with the stepper motors, servo and marker is shown in \autoref{fig:scad_carriage}. |
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\begin{figure} |
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\centering |
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\includegraphics[width=0.8\linewidth]{graphics/scad_scara_circles.png} |
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\caption{CAD of the SCARA configuration, with the end-effector orientated in the lower left corner of the operating area. |
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The configuration has been adapted at the two circled points, to resolve collisions in this orientation. |
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An indentation was made to ensure that the arm could make the required corner. |
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Furthermore, the bottom linkage has been moved from above to below the actuated joints, as this linkage would otherwise collide with the end-effector.} |
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\label{fig:scad_clearance} |
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\end{figure} |
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\subsection{Mechanical Construction} |
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\begin{figure} |
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\centering |
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\includegraphics[width=0.8\linewidth]{graphics/scad_carriage.png} |
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\caption{Rendered 3D model of the SCARA, including steppers, marker and servo.} |
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\label{fig:scad_carriage} |
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\end{figure} |
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\subsection{Implementing Behavior} |
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Now with a physical SCARA, the last step is to implement the behavior. |
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