## 3 Results
### Grasping System
#### 3.1.3 Flexible Element  
In designing the robot gripper, an ideal system would feature a minimum number of actuators and the ability to grasp different objects of varying geometries. To achieve this, the design incorporates a flexible sector capable of deforming to match the shape of various objects, encompassing them completely. This allows the gripper to maximize the surface  
Figure 3: (**a**) Handle which holds the hard shell and actuates the gripping mechanism through the rack on it and (**b**) rubber stop, which is a mechanical stop printed out of TPU that prevents the handle and rack from moving off the body of the gripper. Figure 2: (**a**) Hard shell for holding flexible element and (**b**) locking mechanism to hold the flexible element tightly during rotation and fast movement of the manipulator. in contact with the object, thereby increasing the frictional force applied. Furthermore, since the gripping capability of the gripper relies solely on the formability of the flexible element around objects, it results in a form-closure grasp. Consequently, an open-loop control system proves sufficient, eliminating the need for feedback. The chosen material's softness and robustness enable the gripper to effectively grasp a diverse range of objects with different textures and weights. Thus, objects can be grasped by the minimum required force and avoid any potential damage. Additionally, the flexible nature of the gripper allows it to readily grip objects with unusual geometries, as more surfaces of the object can come into contact with the gripper. To improve the quality of grasping various objects, two different flexible components with different shapes are designed to be fixed inside the hard shell of the gripper. In the future, more patterns and shapes can be developed to better adapt to specific task requirements. The first design features a mesh pattern and a rectangular shape. There are several reasons for utilizing mesh in this design. Firstly, using mesh makes the surface softer and more flexible, making it ideal for grasping fragile or soft objects. Secondly, incorporating a mesh pattern allows for approximately 50 percent of the TPU material used in the detachable gripper head to be saved, thereby affecting the final product price. Thirdly, using less material reduces the overall weight of the gripper, enabling it to handle heavier objects when grasped by the robotic arm. Lastly, the motor requires less force to compress the soft section, allowing for the use of a lower torque motor (smaller motor) in the gripper, which affects the size, weight, and price. In this design, the surface was extended downward and past the edge of the gripper, allowing it to potentially grasp small and thin objects like coins. Bumps were incorporated to increase the friction between the object and the end effector. This design is capable of easily grasping objects of any size and shape within a range of 7 cm width difference, with an upper limit of 15 cm (for instance 1-8 cm, 5-12 cm, etc.). The rectangular flexible element with a mesh design is shown in Figure 4.  
Although using a mesh pattern has many advantages, as mentioned before, the design becomes too soft, resulting in variable and uncertain deformation of the soft component when grasping objects. To counteract this and add some strength to the gripper, angle bars were added to each end of the design. To make sure these bars will bend inside of the mechanism in the compressed position, notches were cut out of the bars so that they  
Figure 4: Flexible elements printed out of TPU material and will flex around various objects (**a**) rectangular shape (**b**) curved shape. can bend in the correct direction. These bars and the notches can also be seen in Figure 4a. The thickness of the gripper design plays a critical role in determining its flexibility. By maintaining the shape and pattern of the design while adjusting the overall thickness, varying degrees of flexibility or stiffness can be achieved.