## 3 Results
### User Acceptance  
This section describes the improvements, deteriorations, or lack of variation in the subjective opinions of users based on the type of actuation, developmental stage, and body part supported by the exoskeleton. Subjective opinions have not been deeply investigated in scientific articles. In many cases, scientific publications preferred to focus on objective data rather than exploring user perceptions. However, it should be noted that many of these trials were conducted in controlled environments such as laboratories, and that individual opinions may have been less relevant as the trials were quite removed from real-life work scenarios. Nonetheless, a deep investigation of subjective considerations would have certainly helped to provide a more precise idea of the users' perception of exoskeletons. Based on the data collected, it is possible to assume that the use of exoskeletons has not resulted in a negative perception by users, as in most cases, evaluations were either neutral or positive (Figure 8).  
Figure 8: Studies that reported positive reviews, negative reviews or neutral reviews, in case of active, passive or hybrid exoskeletons (**A**); studies that reported positive reviews, negative reviews or neutral reviews, in case of prototypes and commercial exoskeletons (**B**); studies that reported positive reviews, negative reviews or neutral reviews, in case of exoskeletons supporting different body areas (**C**).  
Regarding active exoskeletons, the cases analyzed have resulted in either positive or neutral evaluations by users (Figure 8A). Positive reviews refer to a decrease in perceived discomfort when using the exoskeleton compared to performing the same task without it [6; 24; 26; 55]. In neutral evaluations, users did not perceive any difference in discomfort with or without the use of the exoskeleton. For passive exoskeletons, in some cases the users have given negative evaluations. In these cases, users have reported on multiple occasions that the weight of the exoskeleton caused strong pressure on a body part, reducing comfort. Positive and neutral evaluations reported for passive exoskeletons are similar to those for active exoskeletons, where a decrease in perceived discomfort with the exoskeleton or no perceived difference is reported without further evaluation. In the case of hybrid exoskeletons, evaluations are only positive, as the studies reported a good effect on reducing fatigue in the activities for which they are used.  
The rate of positive perceptions was higher in case of commercially available exoskeletons, compared to the positive perceptions collected during the experimental studies with prototypes (Figure 8B). This might be because in many cases, these devices were used in work environments for sufficiently long periods where the user's opinion was collected.  
As the evaluations conducted in such case studies were not in-depth and were rather superficial, it is not possible to further explore these results. However, the results obtained regarding positive, negative, and neutral evaluations in prototype exoskeletons are quite consistent with those of commercially available exoskeletons.  
Figure 8C shows the body parts that have received the most attention of the users, i.e., the upper limbs, the whole body and the lower limbs. For these body areas, the evaluations are mostly neutral. In case of exoskeletons supporting the shoulder, a small proportion of users have given positive feedback.  
In the case of the back, the evaluations are more balanced, with both positive and neutral feedback, as well as negative feedback. Specifically, negative evaluations for the back were concentrated on exoskeletons that support the entire back and the lumbar region, as these areas are particularly difficult to support without risking excessive pressure that reduces user comfort.