## 5 Conclusions  
This work proposes a valuable tool, namely RGB motion analysis system (RGB-MAS), to make a more efficient, and affordable ergonomic risk assessment. Our scope was to aid ergonomists in saving up time doing their job while maintaining highly reliable results. The lengthy part of their job is manually extracting human angles from video analysis based on video captures, by analyzing how ergonomists carry out an RULA assessment. In this context, the paper proposed a system able to speed up angle extraction and RULA calculation. The validation in the laboratory shows the promising performance of the system, suggesting its possible suitability also in real working conditions (e.g., picking activities in the warehouse or manual tasks in the assembly lines), to enable the implementation of more effective health and safety management systems in the future, so as to improve the awareness of MSDs and to increase the efficiency and safety of the factory. Overall, experimental results suggested that the RGB-MAS can be useful to support ergonomists to estimate the RULA score, providing results comparable to those estimated by ergonomic experts. The proposed system allows ergonomists and companies to reduce the cost necessary to perform ergonomic analysis, due to decreasing time for risk assessment. This competitive advantage makes it appealing not only to large-sized enterprises, but also to small and medium-sized enterprises, wishing to improve the working conditions of their workers. The main advantages of the proposed tool are: the ease of use, the wide range of scenarios where it can be installed, its full compatibility with every RGB commercially available camera, no-need calibration, low CPU and GPU performance requirements (i.e., it can process video recordings in a matter of seconds by using a common laptop), and low cost. However, according to the experimental results, the increase in efficiency that the system allows comes at the expense of small errors in angle estimation and ergonomic evaluation: since the proposed system is not based on any calibration procedure and is still affected by perspective distortion problems, it obviously does not reach the accuracy of the Vicon. Nonetheless, if it is true that the Vicon system is to be considered as the absolute truth as far as accuracy is concerned, it is also true that using it in a real working environment is actually impossible, since it greatly suffers problem occlusion (even the presence of an object such as a small box can determine the loss of body tracking), and requires:  
* A high amount of highly expensive cameras, placed in the space in a way that is impracticable in a real work environment. * A preliminary calibration procedure. * The use of wearable markers may invalidate the quality of the measurement as they are invasive. Future studies should aim to improve the current functionalities of the proposed system. Currently, the system is incapable of automatically computing RULA scores. A spreadsheet based on the derived angles is filled to obtain them. However, it should not be difficult to implement such functionality. In particular, future studies should be focused to implement a direct stream of the angles extracted by the RGB-MAS system to a structured, ergonomic risk assessment software (e.g., Siemens Jack) to animate a virtual mannikin, again automatically obtaining RULA scores. Moreover, the proposed system cannot predict hand- and wrist-related angles: further research might cope with this issue and try to fill the gap. For example, possible solutions can be those proposed in [56; 57]. For a broader application of the proposed RGB-MAS system, other efforts should be made to improve the angles prediction accuracy. Moreover, the main current issue is that it is not always possible to correctly predict shoulder abduction and flexion angles with non-calibrated cameras, e.g., when the arms are simultaneously showing flexion in the lateral plane and abduction in the frontal plane.