Wheelchair driving strategies: A comparison between standard joystick and gaze-based control.

This paper aims to evaluate and compare the driving performances achieved with a power wheelchair using a standard joystick versus a novel gaze-based technology. The gaze-based interface, called RoboEYE, involves a novel paradigm of computer interaction that handles the receipt of information from an eye tracker, using it as a continuous input for wheelchair navigation. A pool of 36 subjects has tested both technologies in a circuit designed considering the Wheelchair Skill Test. The experimental analysis involved evaluations of specific metrics of motion and the submission of questionnaires to collect required information about perceived feelings and mental workload. The joystick proved to be the best driving interface. It turned out to be more accurate and efficient than the gaze-based solution. However, the latter achieved only small differences in driving kinematics. These differences can be considered negligible from an operational point of view, offering a driving experience similar to that achievable with the joystick. Testers reported no particular stress, fatigue, or frustration when switching from one interface to another. These elements suggest that the proposed gaze-based solution is an appropriate alternative for a technology transition driven by a pathological change in the user's condition.

Validation of Marker-Less System for the Assessment of Upper Joints Reaction Forces in Exoskeleton Users.

This paper presents the validation of a marker-less motion capture system used to evaluate the upper limb stress of subjects using exoskeletons for locomotion. The system fuses the human skeletonization provided by commercial 3D cameras with forces exchanged by the user to the ground through upper limbs utilizing instrumented crutches. The aim is to provide a low cost, accurate, and reliable technology useful to provide the trainer a quantitative evaluation of the impact of assisted gait on the subject without the need to use an instrumented gait lab. The reaction forces at the upper limbs' joints are measured to provide a validation focused on clinically relevant quantities for this application. The system was used simultaneously with a reference motion capture system inside a clinical gait analysis lab. An expert user performed 20 walking tests using instrumented crutches and force platforms inside the observed volume. The mechanical model was applied to data from the system and the reference motion capture, and numerical simulations were performed to assess the internal joint reaction of the subject's upper limbs. A comparison between the two results shows a root mean square error of less than 2% of the subject's body weight.