Supernumerary robotic limbs (SRLs) gained increasing interest in the last years for their applicability as healthcare and assistive technologies. These devices can either support or augment human sensorimotor capabilities, allowing users to complete tasks that are more complex than those feasible for their natural limbs. However, for a successful coordination between natural and artificial limbs, intuitiveness of interaction and perception of autonomy are key enabling features, especially for people suffering from motor disorders and impairments. The development of suitable human-robot interfaces is thus fundamental to foster the adoption of SRLs. With this work, we describe how to control an extra degree of freedom by taking advantage of what we defined the Intrinsic Kinematic Null Space, i.e. the redundancy of the human kinematic chain involved in the ongoing task. Obtained results demonstrated that the proposed control strategy is effective for performing complex tasks with a supernumerary robotic finger, and that practice improves users' control ability.

翻译：超数机器人肢体（SRLs）近年来因其作为医疗保健和辅助技术的应用潜力而受到越来越多的关注。这些设备可以支持或增强人类的感觉运动能力，使用户能够完成比其自然肢体更复杂的任务。然而，为了实现自然肢体与人工肢体之间的成功协调，交互的直观性和自主感知是关键使能特征，尤其是对于患有运动障碍和损伤的人群。因此，开发合适的人机接口对于推动SRLs的采用至关重要。在这项工作中，我们描述了如何利用我们定义的内在运动学零空间（即正在执行任务中涉及的人类运动链的冗余性）来控制一个额外的自由度。获得的结果表明，所提出的控制策略对于使用超数机器人手指执行复杂任务是有效的，并且练习能够提高用户的控制能力。