# Gait Phase Estimation Based on User-Walker Interaction Force
## 6 Conclusions and Future Work  
We propose a robust real-time gait phase estimation method that considers asymmetric gait patterns and relies on the user-walker interaction force. In addition, the proposed method uses two AOs (Adaptive Oscillators) that are alternately activated by a switching mechanism. The switching mechanism enables accurate gait phase estimation even for people presenting asymmetric gait. Furthermore, an adaptive rule for an AO parameter improves the transient performance under drastic amplitude changes in the input gait signal. The performance of the proposed method and its underlying techniques were evaluated in simulations. The proposed techniques can improve the accuracy of gait phase estimation for asymmetric gait and sudden amplitude changes. Then, we experimentally validated the proposed method, and we found that (1) the proposed method achieves higher accuracy and robustness than the conventional AO, especially under asymmetric gait elicited by a knee orthosis; (2) the proposed method can estimate the HS instant with high accuracy (54.16 \(\pm\) 53.28 ms), similar to that of a method for offline gait event detection based on the interaction force (46.75 \(\pm\) 50.60 ms).  
From the viewpoint of ethics, we only accepted young healthy subjects in this study. In the future  
1. The application of the proposed method for people who suffer from severe motor impairments will be further investigated;
2. The application of the proposed method for actual wheel walker users under different conditions (straight and curve walking) will be further investigated;
3. The interaction forces to be detected at both sides will be used to minimize the influence of misdetections of HSs (heel strikes).  
as were presented in the discussion section.  
Moreover, we will apply the proposed method for improving the effectiveness of physical training for elderly people with a smart walker.  
Methodology, Y.Y. and P.L.; writing original draft preparation, P.L.; writing--review, X.W., Y.A., and Y.Y.; resources, K.Y. and M.Y.; supervision, Y.Y.; fund acquisition, Y.Y. and K.Y. All authors have read and agreed to the published version of the manuscript.  
This work was supported by Center of Innovation (JPMJCE1317) Program run at Nagoya University, which is driven by Japan Science and Technology Agency. This work was also supported in part by The Research Funding for Longevity Sciences (21-21) from National Center for Geriatrics and Gerontology (NCGG), Japan.  
The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the ethics committee of the Department of Mechanical Systems Engineering, Nagoya University (approval number: 21-10).  
Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.  
Data Availability Statement: Data available on request due to ethical restrictions.  
**Acknowledgments:** The authors would like to thank [PERSON] for his advice and [PERSON] for providing us the opportunity to study in the project of \"Development of ICT and robot for the everyday life of older adults\".  
**Conflicts of Interest:** The authors declare no conflict of interest.