Improve First dev Cycle section

content/case_experiment_end-effector.tex

@@ -54,24 +54,42 @@ Fortunately, this failure did give valuable insight on the design method.
         \label{fig:gripper}
     \end{figure}
 
-    \subsection{End-effector model}
+    \subsection{Rapid Development of the End-Effector}
         The end-effector will operate as an interface between the SCARA and the different tools.
         For that it has to be able to grab and release the tools.
-        The initial design is shown in \autoref{fig:gripper}. 
-        With only some experience in modelling with collisions the decision was made to try to make some collisions in the 20-sim 3D mechanics editor.
-        Unfortunately, collisions in a 20-sim model are difficult.
+        The end-effector is mounted at the end of the SCARA.
+
+        The development starts with an initial design of the system.
+        The next step is to develop that further into a model and prototype.
+        This development did not get past the basic model implementation due to unforeseen difficulties.
+        However, the evaluation gave new useful insight on the design plan.
+
+        \subsubsection{Initial design}
+        There are multiple options to connect a tool with a moving arm.
+        However, there is a trade-off to be made with the SCARA feature, the heavier the end-effector is, the more force the SCARA must deliver.
+        And because the goal is to make the SCARA light and quick, this end-effector should be light-weight.
+        The best options in this case is to go with a simple spring-loaded clamp.
+        It is light-weight, and provides sufficient clamping force and precision for this application.
+        To release the tool, the clamp must be forced open.
+        Instead of using a servo, the movement of the SCARA can force the clamp open, resulting in a significant simplification of the design.
+        The initial design of the clamp and the operation is shown in \autoref{fig:gripper}. 
+
+        \subsubsection{Behavior Modelling}
+        The next step is to implement this design with the corresponding behavior in a dynamic model.
+        The challenge in this case is the modelling of the contact dynamics.
+        Based on some experience in modelling with collisions, I decided to use the 20-sim 3D mechanics editor.
         There is little tooling available and there are no debugging options if the model does not behave as expected.
         The marker kept falling trough the gripper or flew away.
         With the small amount of progress made in two days the implementation was not promising. 
-        A crash in the software caused the model to corrupt, where the complete configuration of the shapes and their collisions was lost.
-        Therefore it was decided that end-effector would be removed from the design.
+        A system freeze caused the model to corrupt, where the complete configuration of the shapes and their collisions was lost.
+        Based on the loss of work and the low feasibility of the implementation, it was decided that the end-effector would no longer be part of the design.
 
         With the end-effector removed, the SCARA will get a direct connection with the marker.
-        The lifting of the marker will be included in the SCARA as well.
+        The lifting of the marker from the will be included in the SCARA as well.
         Furthermore, this means that the wiping will no be possible via the SCARA.
 
         \subsubsection{Evaluation}
-            The lost progress of the model is unfortunate, but the implementation did not go expected anyway.
+            The lost progress of the model is unfortunate, but the implementation did not go as expected anyway.
             It was probably for the best as it forced an evaluation of the design and avoided a tunnel vision while trying to get it to work.
             However, it did show the value of the risk/time analysis.
             This early failure resulted in changes for other components.