# Development and Biomechanical Evaluation of a Back Exoskeleton to Support Lifting Tasks
## 5 Discussion
### Exoskeleton Design  
The purpose of this design approach was to develop an exoskeleton that physically supports care workers during lifting tasks. Therefore, the design was tailored to the needs of healthcare professionals, considering the physical demands of their daily tasks. The priority was to create a lightweight and compact system that could be worn close to the body without restricting natural movements. This requirement aligns with the findings of previous studies (e.g., [25]), which emphasized that wearing comfort is a critical factor for the acceptance of exoskeletons. To ensure high wearing comfort, the exoskeleton was primarily constructed using flexible textile materials. Textile-based designs have been increasingly explored in exoskeleton research [26] because they allow better adaptability to different body shapes and reduce pressure points. In our design, textiles were used at human-system interfaces to ensure optimal comfort and fit. This contrasts with rigid exoskeletons, which tend to cause discomfort when worn for extended periods of time [27, 28]. The exoskeleton utilizes a cable-driven force transmission system, which enables the efficient transfer of actuation forces from electric motors to the human body. In this design, cables are wound around spools and tensioned by actuators, thereby generating assistive forces that support the user during lifting tasks. This cable-driven approach is commonly used in soft exosuits (e.g., [29, 30]) due to its ability to transmit forces over a distance while allowing for a more compact and lightweight actuator placement. A key advantage of cable-driven systems is their flexibility, which allows actuators to be positioned away from the joints, thereby reducing local bulkiness and maintaining user mobility. Compared to rigid linkages, cable-driven systems offer a more compliant interaction with the human body, which is particularly beneficial in applications requiring comfort and adaptability, such as healthcare exoskeletons. However, cable-driven transmission also presents challenges. One issue is the compression forces that arise in the opposite direction of the tensile force. These undesired forces must be absorbed either by the exoskeleton structure or redirected away from the user's body to prevent discomfort or instability. Furthermore, friction and backlash effects can reduce the efficiency of force transmission, leading to delays in the response time and potential energy losses [31, 32]. To mitigate these drawbacks, low-friction sheaths can be used to guide the cables, and optimized control algorithms can help compensate for transmission delays. Rigid components, such as plastic and aluminum elements, were strategically integrated for force transmission. These materials enable efficient force transfer without a significant increase in weight. Similar hybrid designs have been employed in other soft exosuits [33], demonstrating that the combination of soft and rigid structures can effectively balance comfort and functionality. While the current design offers high usability and comfort, there is still room for further improvement. One key area is dynamic adaptability, where future iterations could integrate real-time motion adaptation algorithms based on AI-driven movement prediction. This enhances the responsiveness of the assistive force, allowing for more seamless support during lifting tasks. Some users reported a slight delay in the system response, particularly during fast movements. This reduced responsiveness can be attributed to the system's structural composition, which primarily relies on soft and textile materials. While these materials ensure comfort and adaptability, they also introduce flexibility, leading to shifts in human\(-\)technology interfaces and causing minor delays in force transmission. As a result, the overall acceleration and speed capabilities of the exoskeleton were affected. Although this aspect was not a major concern for all participants, it represents a relevant functional limitation that requires further research.