# Comparison of Single-Arm and Dual-Arm Collaborative Robots in Precision Assembly
## 1 Introduction  
Robotization of technological processes is one of the aspects of Industry 4.0. Progressive competition and a dynamically changing market result in the need for robotization of production processes, which translates into increased efficiency, precision and quality of manufactured products [1]. Robotization of processes is of particular importance in many industries: automotive, furniture, metal processing, electronics and medicine [2]. Most applications of industrial robots concern tasks related to object manipulation (pick and place), as well as welding, gluing, patletizing [3, 4], painting and quality assurance [5, 6]. All of these operations can be part of the assembly process, which can be robotized. Statistical data from robot suppliers and robotics associations consolidated by the IFR Statistical Department indicate that the electronics industry has been the main recipient ofindustrial robots since 2020. In 2021, the number of installed robots increased by 24%, and in 2022 it increased by 10%. A growing trend is the use of collaborative robots (cobots) in electronics assembly processes. The market share of collaborative robots, which include the ABB YuMi robots, increased by 31%. Since 2017, the demand for robots in the electronics industry has increased by an average of 5% per year. The overall long-term growth trend is expected to continue [7]. Statistics provide grounds for research on the theoretical and practical use of collaborative robots, especially those used in electronic parts assembly processes. The implementation of robotization and the selection of its most advantageous solution are based on selection criteria such as costs and time of the manufacturing process. To assess which variant is the most advantageous (for the selected evaluation criterion), the station or robotic line is modeled and simulated in a virtual environment. In such an environment, manipulation [8; 9; 10], grinding [11], palletizing [12], painting, milling, welding [13], spraying [14], sealing [15] and 3D printing [16] operations can be simulated. The authors of these publications indicate the benefits of offline robot programming, mainly checking the program code without any interruptions in the ongoing process, assessing the path and movement parameters of the tool or gripper and, above all, the ability to analyze the time and costs of the programmed solution. [PERSON] et al. discussed the advantages of simulating the work of collaborative robots in precise and expensive manufacturing processes to best reflect the real process [17]. One of the popular collaborative robots is ABB's YuMi, with an ergonomic shape modeled on human arms. The robot has 14 axes, 7 on each arm. This robot is equipped with many safety elements, which makes it possible to eliminate expensive security measures such as barriers, curtains and fences and allows work in the immediate vicinity of people. [PERSON] et al. developed dynamic safety zones to activate the robot to stop at a user-defined distance from an object [18]. The ABB YuMi collaborative robot allows for the effective implementation of assembly processes where other industrial robots require special equipment and advanced grippers. The accuracy and repeatability of positioning at the level of 0.02 mm [19] allows the robot to be used in precise and repeatable assembly processes [20]. Using the YuMi robot, it is possible to simulate the technological process using one or two arms, which is impossible in the case of standard industrial robots of one kinematic structure. Precision engineering is an important element of modern manufacturing processes affecting quality, efficiency and innovation [21]. The interest in collaborative robots in terms of identifying research and development opportunities, as well as manufacturing applicability is one of the most important topics of publications in recent years.