A task description model for robotic rehabilitation

The desire to produce robots to aid in physical neurorehabilitation has led to the control paradigm Assistance-As-Needed. This paradigm aims to assist patients in performing physical rehabilitation tasks whilst providing the least amount of assistance required, maximizing the patient´s effort which is essential for recovery. Ideally the provided assistance equals the gap between the capability required to perform the task and the patient´s available capability. Current implementations derive a measure of this gap by critiquing task performance based on some criteria. This paper presents a task description model for tasks performed by a patient´s limb, allowing physical requirements to be calculated. Applied to two upper limb tasks typical of rehabilitation and daily activities, the effect of task variations on the task´s physical requirements are observed. It is proposed that using the task description model to compensate for changing task requirements will allow better support by providing assistance closer to the true needs of the patient.