## 4 Conclusions  
This study is significant in that it provides a new 3 DP pHRI based on the sizing system that does not require baseline remodeling for the customization of a wearable robot to fit a patient's body shape. The effectiveness of the innovation was verified by evaluating its conformity of shape and dimensions. The new 3 DP pHRI was developed by segmenting size sections and creating an average human body model for each. The conformity of shape and dimensions was evaluated by visual observation and shape deviation analysis for 10 persons with paraplegia. The main research results are summarized as follows:1. For size segmentation, 199 2D human body measurement data points were used as sample data. Using the grid method technique, 18 size sections meeting the coverage rate of 4-7% each, and a total coverage rate of 90.5% were defined.
2. For the generation of the average human body model, 195 3D human body shape model data items were used as sample data, and a wireframe modeling technique based on body-section analysis was used to generate the average human body model for each of the 18 size sections.
3. For system development, 18 trunk and nine shank sections were produced as sizing subsystems by referring to the surface shapes of the generated 18 average human body models.
4. From the visual observation, a biased tendency of the shank-sizing system was identified. From the shape deviation analysis, all trunk and shank subsystems showed conformity of shape and dimensions at an appropriate level with a deviation range of 10 mm.  
The 3 DP-pHRI system developed in this study can be applied to various wearable robot pHRI situations, and it is expected to contribute to a useful pHRI template library through follow-up research. In this study, a body shape database of people without disability was used to develop the sizing system, owing to the practical difficulty of obtaining such data from paraplegia patients. Owing to this limitation, the coverage rate bias mentioned above was identified. To overcome this problem, the application of structural parameter shape designs to induce variable controllability should be considered next. The follow-up studies will involve research on a structural parameter shape design to reinforce the shape control functions for the 3 DP-pHRI based on the sizing system, as well as an empirical clinical evaluation research considering the coupling relationship with the robot.  
Conceptualization, C.-Y.K.; methodology, C.-Y.K. and J.-S.J.; software, C.-Y.K.; validation, C.-Y.K., J.-S.J. and G.-S.K.; investigation, C.-Y.K.; data curation, C.-Y.K. and J.-S.J.; writing--original draft preparation, C.-Y.K. and J.-S.J.; writing--review and editing.-S.J. and G.-S.K.; visualization, C.-Y.K.; supervision, J.-S.J.; project administration, G.-S.K. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program (Project Number: 20003914)) and was funded by the Ministry of Trade, Industry and Energy (MOTIE, South Korea).  
The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Rehabilitation Engineering Research Institute (protocol code RERI-IRB-200318-2 and 18 March 2020).  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
The authors declare no conflict of interest.