Determining natural and accessible gestures using uncontrolled manifolds and cybernetics

Recent studies revealed that hand gesture-based interfaces can complement therapies for individuals with upper motor impairments and reduce the need of traditional rehabilitation sessions through hospital visits. Unfortunately, existing gesture-based interfaces have been developed without considering the physical limitations of users with motor impairments. An analytic approach was presented in our previous work to convert existing gesture-based interfaces designed for able-bodied individuals to be usable by individuals with quadriplegia using the Laban Theory of Movement. This paper extends the previous work by including gesture variability analysis (based on Uncontrolled Manifolds theory) and robotic execution. A WAM robotic arm was used to mimic gesture trajectories and a physical metric was empirically obtained to evaluate the physical effort of each gesture. At last, an integration method was presented to determine the accessible gesture set based on both the stability and empirical robot execution. For all the gesture classes, the accessible gestures were found to lie within 31% of the optimality of stability and work, respectively.