# Detecting and Solving Tube Entanglement in Bin Picking Operations
## 4 Experiments
### Results  
The _Entangled Tubes Bin Picking_ dataset from the authors' previous research [3] was expanded to include the files of all the point clouds acquired by the 3D scanner during the experiments. The dataset is available at [[https://github.com/GoncaloLeao/Entangled-Tubes-Bin-Picking-Dataset](https://github.com/GoncaloLeao/Entangled-Tubes-Bin-Picking-Dataset)]([https://github.com/GoncaloLeao/Entangled-Tubes-Bin-Picking-Dataset](https://github.com/GoncaloLeao/Entangled-Tubes-Bin-Picking-Dataset)). This repository also includes a link to raw footage of all the experiments. Table 3 presents the solution's success rate for emptying the bin. The six unsuccessful cases were due to tubes that moved to the corners of the bin, where the scanner could not detect them, causing the round to end prematurely. The sensor could not scan the bin from a higher position since the cloud points it acquired had too much noise due to the scanning distance exceeding by a large amount the optimal range. A smaller bin was not used so that the robot could freely experiment escape trajectories without the risk of either the gripper or the grasped tube colliding with the bin's walls. As future work, multiple scans of the bin from different positions can be acquired or a sensor with a larger working area can be used. In all of the rounds, when all of the tubes were brought to the destination area, the robot was able to infer the bin was empty by the latest acquired point cloud and end the picking process. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Phase** & **Parameter** & **Set A** & **Set B** \\ \hline Tube & Cloud point size after filtering & 100,000 \\ modeling & & \\ \hline Tube & Tube minimum length & 35 cm & 30 cm \\ classification & & \\ \hline \multirow{4}{*}{Trajectory synthesis} & Upwards trajectory movement & 40 cm \\  & Escape trajectory first upwards movement & 2 cm \\  & Escape trajectory second upwards movement & 40 cm \\  & \(d_{const}\) & 3 cm \\ \hline Grasp & Minimum distance between grasping points and cylinder bases & 2 cm \\  & Maximum allowable amount of points in the gripper’s bounding boxes & 20 \\ \hline \multirow{4}{*}{Grasp evaluation} & \(disp_{max}\) & 1 m \\  & \(H_{cost\_weight}\) & 0.2 \\  & \(C_{cost\_weight}\) & 0.5 \\  & \(T_{cost\_weight}\) & 0.3 \\ \hline Entanglement & \multirow{2}{*}{Rotation angle} & \multirow{2}{*}{45\({}^{\circ}\)} \\   resolution & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameter values used in the experiments. \begin{table}
\begin{tabular}{c c} \hline \hline
**Set A** & 90\% \\ \hline
**Set B** & 80\% \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Percentages of rounds where the bin was successfully emptied. There were no cases in which multiple tubes were carried to the destination area or where a tube fell outside the bin. Therefore, every time a single tube was lifted from the bin, it always reached the destination area. In the results and discussion that follow, let a _picked tube_ be a real-life tube that was successfully placed in the destination area in a given round, possibly after multiple attempts (the last one being the _successful attempt_ or _successful pick_). Table 4 shows the percentage of picked tubes that were successfully placed on the first try. The high overall success rates alongside the significant amount of picked tubes indicate that the proposed algorithm had a very positive performance for both tube sets. As expected, the success rate for Set B is slightly smaller than for Set A since the former tubes' geometry and material made them more prone to entanglement. In Set B, the lowest success rate corresponds to cases where there were seven tubes in the bin, which is likely due to the presence of more complex tube arrangements. Conversely, in both sets, there is a 100% success rate of picking tubes at the first attempt when the bin only contains one or two objects. The results seem to indicate that the success rate does not increase at a constant rate as the number of remaining tubes decreases.