Abstract
This study concerns the difficulty in accessing computers faced by people with Dyskinetic Cerebral Palsy (DCP). Thus diminishing their opportunities to communicate or learn. This population usually needs an alternative input human-computer interface (HCI). The paper presents an alternative multimodal HCI that incorporates a head-mounted interface and superficial electromyography sensors (sEMG). The aim of the study is to assess the usability and the suitability of these two HCI devices. Six non-disabled subjects and ten subjects with DCP participated in the iterative process in which each test follows an improvement of an input. The results indicated that for both systems, the improvements in the usability are remarkable when there were previous training programmes with both interfaces. These tests allowed the identification of the main difficulties associated with disability: poor control of the voluntary muscle contraction, which affects the EMG signal, and abnormal postures, which affect the head-mounted interface control. Regarding the EMG signal, the characterisation of the involuntary patterns of muscle contractions may prevent false positives. In the case of the inertial interface, a relative mode control (based on the velocity of the movement instead of posture) may be a solution to increasing the usability and task performance.