# Using A Rotary Spring-Driven Gripper to Manipulate Objects of Diverse Sizes and Shapes
## 4 Discussions and Conclusions  
This paper introduces a novel mechanical gripper design that is specifically tailored for handling objects with diameters ranging from 5 cm to 9 cm. This range is selected based on common fruits and bottles that are typically encountered in food and beverage handling and packaging applications. The gripper's primary purpose is to facilitate the picking and placing of fruits, vegetables, and bottles in grocery stores or warehouses. The design offers ease of actuation, requiring only one actuator and eliminating the need for a closed-loop control system. It features a rotational spring-based grasping mechanism, which can be replaced depending on the weight and texture of the target objects. By conducting stress analyses and force calculations, the gripper's operational performance was optimized. The analytical studies provided valuable insights, leading to the system meeting its specifications while offering opportunities for enhancements in weight and strength. Through the motion study results, the system could accurately estimate the torque required for achieving the desired range of motion. Likewise, the topology studies conducted on certain components enabled material reduction without compromising their structural strength. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Joint Orientation Angles for All Six Joints** & **Determinant** & **Rank** \\
**q1, q2, q3, q4, q5, q6 (Degrees)** & & \\ \hline
1.98, 3.10, \(-\)9.94, \(-\)3.12, 56.79, 6.58 & \(-\)0.0196 & 6 \\ \hline \(-\)26.19, 20.20, \(-\)27.12, 17.75, 59.85, \(-\)26.26 & \(-\)0.0198 & 6 \\ \hline \(-\)26.19, 18.38, 6.15, 30.32, 31.47, \(-\)43.63 & \(-\)0.0152 & 6 \\ \hline \(-\)26.19, 22.05, 12.92, 42.40, 43.01, \(-\)57.16 & \(-\)0.0186 & 6 \\ \hline \(-\)26.19, 19.09, 8.08, 32.67, 29.24, \(-\)46.35 & \(-\)0.0143 & 6 \\ \hline \(-\)26.19, 18.49, \(-\)17.33, 19.31, 52.86, \(-\)29.06 & \(-\)0.0118 & 6 \\ \hline
15.60, 12.09, \(-\)8.52, 15.09, 48.65, 25.56 & \(-\)0.0199 & 6 \\ \hline
39.66, 35.63, \(-\)39.88, \(-\)28.25, 64.97, 48.83 & \(-\)0.0144 & 6 \\ \hline
39.66, 34.93, \(-\)6.41, \(-\)44.15, 38.01, 73.47 & \(-\)0.0172 & 6 \\ \hline
39.66, 38.77, \(-\)2.22, \(-\)52.66, 32.66, 83.87 & \(-\)0.0159 & 6 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Determinant and rank of the Jacobian matrices from MATLAB®. Figure 16: (**a**) Grasping a tomato; (**b**) grasping a guava; (**c**) grasping a hand sanitizer bottle (all bottom views). The prototype, which was fabricated using additive manufacturing technology from ABS plastic, underwent successful testing with the intended target objects, which mainly include fruits, vegetables, and other grocery store items. It was observed that the spring and piston's stroke lengths are just as much as it needs and vary depending on the object's shape. To conclude, the research lays out an innovative design as a foundation for vast areas of research and advancement in the material handling and packaging industries. In future iterations of the gripper, using 6061 aluminum alloy for fabrication will allow for a more compact and smaller form without compromising the strength. Vapor smoothing is recommended for ABS plastic parts to minimize friction. Furthermore, incorporating proper geometric dimensioning and tolerancing (GD&T) techniques can help to eliminate undesired bending moments and high-friction contacts. The electronic control configuration of the gripper, via the robotic arm controller, will contribute to a lighter and more compact design, eliminating the need for a top housing for the motor controller and power. Additionally, the integration of a camera for object detection holds the potential to enable full autonomy in the gripper's operation while exploring its application in space exploration and sample collection.