# Development, Experimental Assessment, and Application of a Vacuum-Driven Soft Bending Actuator
## 4 Vacuum-Driven Soft Robotic Gripper Assembly  
The previous experimental assessments confirmed the outstanding performance of the developed novel VSBA. The proposed VSBA design demonstrated its capability for integration into real mechatronic systems, leading to the development of a soft robotic gripper. The robotic gripper is a sophisticated mechatronic system, typically consisting of three actuators that work together to grasp an object for subsequent manipulation. The advantages of using soft actuators in robotic grippers include the ability to adapt to objects of irregular shapes and to control the force applied by the actuators on the object. With soft pneumatic actuators, the force can be easily controlled by altering the vacuum pressure with a pressure regulator, allowing for precise control of the gripping force. Based on the results indicating that the VSBA-1 generates the highest maximum force and achieves a bending angle of up to 140\({}^{\circ}\), it was decided to incorporate three VSBA-1s into the soft robotic gripper. The design of the soft robotic gripper follows the principle of simplicity, featuring a configuration in which three actuators are evenly spaced at 120\({}^{\circ}\) intervals along a circular arrangement. This assembly is achieved using a triangular support plate, which has holes for mounting the actuators according to a predefined geometry, as shown in Figure 8a. The actuators are fastened to the plate with screws on the upper lid, while the lower end of the actuators allows for bending. The support plate was cut from a 4 mm thick wooden board, with the required holes drilled. To enable soft object grasping, a grasping element was designed and mounted on the VSBA-1's lower lid. The grasping element consists of two parts: the first part, the angular part, is fastened to the actuator's lower lid, and is designed with a 30\({}^{\circ}\) inclination, allowing optimal object grasping for the VSBA-1's dimensions. The second part, the grasping part, is mounted to the angular part and designed with a flexible surface that adapts to the shape of the object during grasping. The grasping part is primarily designed for grasping cylindrical objects but also allows for the grasping of objects with various shapes. The angular part was made using 3D printing technology with PLA material due to the requirement for strength, while the grasping part was made from TPU for flexibility requirements. The flexible surface of the gripper part allows it to adapt to the shape of the object, but the low friction between the TPU material and the object often leads to slipping. To address this issue, a thin layer of rubber was added to the flexible surface of the gripper part. Experimental assessment of the robotic gripper includes tests of its ability to grasp objects of different shapes, as well as an analysis of the maximum gripping force and the maximum holding force. Various laboratory tests were performed, starting with an evaluation of the gripper's ability to grasp objects with standard shapes, including cylindrical, prismatic, spherical, and similar forms. The tests confirmed the gripper's capability to reliably grasp all tested objects, with optimal performance observed when handling cylindrical and spherical objects. For prismatic objects, there were instances where the gripper's contact surface initially engaged an edge of the prism, causing the object to rotate until the gripper successfully grasped its flat surfaces. This rotation occurs as a result of the actuators' capability to bend in different axes other than their primary operation axes. Such bending was observed in earlier tests on maximum blocking force (see Section 2.1). However, in the soft robotic gripper, this characteristic of the actuators proved advantageous, as it allowed the gripper to adapt to the object's shape while grasping. Then, the gripper was tested with various objects of irregular shapes.