Safety analysis on human-robot collaboration in heavy assembly task
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Manufacturing assembly industry has traditionally utilized human labor to perform assembly tasks manually. With the introduction of industrial robots, fully automated solutions have provided an opportunity to perform complex and repetitive tasks and assist in the assembly of heavy components. In recent years, improvement in robot technologies and changes in safety legislation have enabled new human-robot collaboration (HRC) concepts which have drawn attention of manufacturers. HRC uses characteristics of dexterity and flexibility of human and repeatability and precision of robots to increase the flexibility of the system, decrease the cost of labor in production and improve ergonomics in the design of shared workspace. The operator safety is one of the challenges inside the HRC environment. The safety concerns could be altered with different levels of physical interactions between robot and human. This thesis aimed to develop solution for analyzing the safety functions on different human-robot interaction (HRI) levels. The approach was started with the classification of tasks between human and robot. In this thesis, assembly sequences were designed to fulfill the requirements of each interaction levels of HRI. These experiments were providing evaluation tables for analyzing the safety functions in HRI levels. The primary objective of this thesis is to design the HRC system with suitable safety functions. The safety of the workstation was developed using a combination of hardware and software. Laser scanners employed to detect the presence of a human in hazard areas and ABB SafeMove add-on were configured to exploit safety signals to the robot controller for adopting safety functions such as safety-rated monitored stop, and speed and separation monitoring. In this thesis, time work study analysis was demonstrated that the implementation of HRC decreases the fatigue and the injury risks of the operator and enhances the ergonomics for the operators. The study of safety functions through different HRI levels proved that with an increase of physical interactions it was necessary to employ multiple safety functions to prohibit collisions between robot and human.