# Comparison of Single-Arm and Dual-Arm Collaborative Robots in Precision Assembly
## 4 Conclusions  
Collaborative robots are becoming more and more widely used in assembly processes due to their precision of movements and the possibility of installation in the direct work zone of humans. Comparative research on collaborative robots is part of the current trend in the industry of using precision robots that can cooperate with humans and are additionally equipped with vision. Dual-arm robots can simultaneously perform various activities assigned to each of the arms separately. It is important to eliminate potential collisions that can occur not only with station equipment but also between arms. Analyzing the work of collaborative robots in a virtual simulation environment has many benefits, including, most importantly, monitoring information about the movement trajectory, collisions, process time, energy consumption and movement speed. Offline programming capabilities facilitate the procedure of building robotic stations, as well as selecting robots and robot movement parameters without interruptions in the ongoing production process. The differences between the two robot variants include time: 14 s in favor of the dual-arm robot and 21 s as a disadvantage of the single-arm robot. The time is influenced by the speed of TCP movement, with the achievement of the programmed speed depending on the length of the robot's TCP path. In most cases, the maximum programmed speed of 200 mm/s was achieved. The choice of speed also depends on the precision of the task being performed, and it was reduced to 50 mm/s during the strict assembly task. The single-arm robot proved to be more energy-efficient, but due to the more favorable process execution time of the dual-arm robot, it turned out to be a more cost-effective robot in the long run. During one assembly cycle of the analyzed process, a single-arm robot consumes 205.8 J of energy in 20.6 s. whereas a dual-arm robot consumes 260 J in 13.6 s. Based on these results, it can be concluded that a single-arm robot is more energy efficient. However, the two-arm robot performs the assembly operation faster and using 20% more energy, which could prove more profitable in the case of large-scale production. Analyzing the cost values, it can be concluded that both robots are profitable, and their implementation would pay off after about three months. The cost-effectiveness of the dual-arm robot paid off after eight months of operation. The obtained results are universal, and the simulation performed in a similar way allows for a comparison of collaborative robots in other technological processes. These studies can demonstrate a procedure for evaluating industrial robots in an offline pro  
Figure 17: The cumulative profit of a dual-arm robot versus a single-arm robot. gramming mode, suggesting a way in which other robotic manufacturing processes can be verified. In addition, these studies present an interesting case study of computer motherboard assembly, from the design stage of the robotic station, through robot programming and comparative analysis of both solutions, time, speed, acceleration, energy consumption and costs. The simulation results were obtained from three tests. The virtual environment is distinguished by ideal conditions without disruptions and thus the repeatability of results. Therefore, the compared criteria of both robot variants, such as time, speed, acceleration and energy consumption, were characterized by stability. The manufacturer states that the simulated work in the virtual environment corresponds to that in reality, especially for new and regularly inspected robots. Implementation of the pseudocode developed in the virtual environment in the real robot station should therefore lead to obtaining the same results. The limitations of virtual environments are the lack of consideration of random disruptions or variable conditions, including robot adaptability, maintenance requirements or effective human-robot interaction.