###### Abstract  
Compliant mechanisms are gaining popularity in many different fields, such as in microelectromechanical systems (MEMS), medical applications and health care, opto-mechantonic technology, aerospace engineering, and semiconductor equipment. One of the areas for utilizing compliant mechanisms is building models of human hand counterparts. These models are often used as grasping and rehabilitation devices. Because of their properties, creating a human hand counterpart with compliant mechanisms is a much better choice compared with the models with traditional mechanisms; it looks more realistic, and its movements are much more natural compared with models with a traditional mechanism. A method of modeling and designing such a bio-inspired mechanism, as well as its experimental analysis with various forces applied, is presented in this paper. Two prototypes of the compliant fingers were obtained by 3D printing, and the calculation of the bending angle values was achieved by applying image processing to camera images of the compliant fingers' prototypes. Image processing was conducted on images taken for both loaded and unloaded 3D-printed compliant finger prototype positions. Finally, these bending angle results are compared with the results obtained by Finite Element Method (FEM) analysis and experimental results acquired by a digital protractor. compliant mechanism; flexure hinge; computer vision; FEM; hand rehabilitation 202320  
group and those that have joint compliance. The first group uses the soft robotic approach, and the papers [1; 2; 3; 4; 5] show the state of the art, development, and future progress of this group. A soft touch approach is applied in this case, where the entire length of flexible elements is used for different applications. Applications of such soft gripping devices are different, such as actuators, sensors, medical tools, and rehabilitation devices. Grippers are perhaps the most abundant in this area. The study in paper [6] presents a robotic end-effector that perfectly replicates the actions of the human hand in terms of gripping and manipulating items. The soft robotic gripper shown in the paper [7] consists of three soft finger bends and one passively adaptive palm. In practice, the soft gripper could achieve a gripping force of 40 N at low actuation pressure below 100 kPa and, thus, can pick up objects of all sizes with a convex shape. Similarly, paper [8] shows a three-breasted gripper with a matched spine of each finger made of 3D-printed polylactic acid (PLA) materials sandwiched between thin-layer materials. Here, one can cite works [9] and [10], where the modeled grippers do not take the shell of the hand as a model but are free-form structures obtained by topological optimization. A diverse series of alternative uses of structural compliance to develop simple, adaptive, compliant, and/or underactuated robotic graspers and arms that can efficiently and robustly perform various grasping and dexterous hand manipulation tasks are presented in [11]. The same study demonstrates the application based on the joints' flexibility. They represent the second group of flexible structures that use the methodology of compliant mechanisms. For the most part, these were inspired by endoskeletons used for grasping applications, and due to their external appearance, they resemble human fingers [12]. In papers [13; 14; 15], mechanisms developed in this way for the needs of the end-effector of the robotic arm are presented. The paper [16] that uses elastic ligaments and antagonistic tendons to construct anthropomorphic joints with multidirectional passive compliance as a substitute for human finger joints can be mentioned here. Papers [17; 18; 19] show a combination of both groups, finger compliances and joint compliances, which is a new approach to soft grippers. Cited paper [18] deserves special attention. In this paper, a pressure sensor is placed on the fingertip of the elastic structure to form a soft robotic functional system.