  Functional upper-limb prosthetic training can improve users performance in
controlling prostheses and has been incorporated into occupational therapy for
individuals in need. In recent years, virtual reality (VR) and augmented
reality (AR) technologies have been shown to be promising avenues to improve
the convenience of rehabilitative prosthesis training systems. However, it is
uncertain if the comprehensive efficacy and effectiveness of VR or AR assistive
tools are adequate compared to conventional prosthetic tools and if not,
whether enhancements can be made through incorporation of other technical
paradigms.
  This work first presents a mixed reality system we developed for prosthesis
control and training. Five able-bodied subjects are involved to perform
three-dimensional object manipulation tasks in analogous AR and VR
environments. Multiple evaluation metrics are applied to assess subjects
performances within the two paradigms. Based on the comparative analysis, we
find that VR-based environment promotes more efficient motion along with higher
task completion rate and path efficiency while AR paradigm allows subjects to
perform motor tasks with shorter time consumed. Another study is conducted to
evaluate the efficiency and feasibility of AR-facilitated prosthesis control
system compared to that in real-world and if any technical additions can be
applied to improve the AR-based system. Three able-bodied subjects were engaged
in the experiment to perform object manipulation tasks in a) physical
environment, b) AR-without-bypass environment, and c) AR-with-bypass
environment. Based on the results obtained from the assessment, we conclude
that while our AR-based system modestly lags behind the effectiveness of
physical systems, the study conducted using a bypass prosthesis suggests that
AR system has the potential to improve the efficacy of prosthesis control.
