**6. Conclusion**

This work presents VIGOR system that has a strong potential for broad significance to the physical and psychological health of people with limited mobility. It is expected that VIGOR may (1) produce an affordable and user-friendly platform which promotes regular physical activity via a seamless interaction between the user and the Tai-Chi model/master; (2) cultivate and enhance interdisciplinary research by integrating the expertise of physical therapy, psychology, computer science, electrical engineering, and structural mechanics; and (3) adapt to other movement modalities (e.g, yoga).

The major research elements include: (1) *Seamless real-time 4D human-machine interaction* based on affordable input/output hardware instruments such as Kinect sensor, foot-pressure sensors, actuator, assistive device/exoskeleton, and VR goggle, etc.; (2) *Kinetic movement grading and identification;* (3) *Adaptive virtual limb generation* over VR/AR and assistive device/exoskeketon; and (4) *Individualized movement choreography*(i.e., creative movement design). As the major research contributions of this work, visible and hierarchical neural network (VHNN) architecture is proposed to recognize and predict human kinetics efficiently; and a polynomial-based, Newton-Raphson algorithm is proposed for efficient optimization. Both techniques play significant roles in small-data problems.

As part of our future work, the clinical effect of VIGOR system will be assessed. Specifically, we plan to evaluate both the user-experience and the feasibility of VIGOR by conducting a few of phases of a human subject study with healthy and mobility-limited adult human subjects. In every phase, subjects will be surveyed and interviewed following exposure to VIGOR. The clinical data will be analyzed using Auto-Regressive Integrated Moving Average (ARIMA) model [44].
