Control of finger movement and force for precision pinch

描述(申请人提供)：用指尖动态抓握和操作(“精确捏”)取决于协调指尖运动和力量的机械能力。产生指尖运动所需的肌肉协调模式不同于施加指尖力量所需的肌肉协调模式：指尖运动取决于肌腱偏移，而指尖力量取决于肌腱张力。像精确掐指这样的灵巧任务需要肌肉的协调来满足两个基本要求：(I)从指尖运动到同一方向的力的转换(例如，快速拿起一支铅笔)；(Ii)指尖运动和不同方向的力的组合(例如，滚动铅笔)。我们将系统地解释食指的肌肉是如何协调的，以满足这两个精准捏合的基本要求。这一认识将为骨科和神经系统疾病以及衰老中精密夹的退变研究提供生物力学基础。 假设一：从指尖运动到力沿同一方向的顺序转换涉及以牺牲运动和力的精度为代价在坐标模式之间进行内插，内插的突发性取决于允许的误差范围。假设II：同时产生指尖在不同方向上的次最大运动和力可以充分限制肌肉相互作用以消除肌肉冗余。为了验证这些假设，我们提出了一种结合行为研究、机器人分析、生物力学建模和身体实验的综合方法。目的1：描述人类用来产生各种食指指尖运动和力量任务的协调模式。肌肉协调模式将被表示为从肌电(EMG)估计的7维向量。目的2：解释肌肉协调模式如何满足任务的机械要求。食指的生物力学模型将预测协调模式，再现在目标1中观察到的运动和力，同时评估肌肉骨骼参数的可变性的影响，并量化肌肉冗余的程度。目的3：通过激活身体手指的肌腱，并将机械输出与随意动作和模型动作进行比较，验证肌电和预测的协调模式。

DESCRIPTION (provided by applicant): Dynamic grasp and manipulation with the fingertips ("precision pinch") depend on the mechanical ability to orchestrate fingertip motion and force. The muscle coordination patterns required to produce fingertip motion differ from those associated with exerting fingertip forces: fingertip motion depends on tendon excursions, whereas fingertip force relies on tendon tensions. Dexterous tasks like precision pinch require the coordination of muscles to fulfill two fundamental requirements: (i) the transition from fingertip motion to force in the same direction (e.g., to quickly pick-up a pencil); and (ii) combinations of fingertip motion and force in different directions (e.g., to roll the pencil). We will systematically explain how the musculature of the index finger is coordinated to fulfill these two fundamental requirements of precision pinch. This understanding will provide the biomechanical foundation for much needed studies on the degeneration of precision pinch in orthopedic and neurologic diseases and in aging. HYPOTHESIS I: The sequential transition from fingertip motion to force along the same direction involves interpolating between coordination patterns at the expense of motion and force accuracy, with the abruptness of the interpolation depending on the allowable margin of error. HYPOTHESIS II: The simultaneous production of submaximal fingertip motion and force in different directions can sufficiently constrain muscle interactions to eliminate muscle redundancy. To test these hypotheses, we propose an integrative approach combining behavioral studies, robotics analysis, biomechanical modeling, and cadaveric experiments. AIM 1: To describe the coordination patterns used by humans to produce a variety of index fingertip motion and force tasks. Muscle coordination patterns will be expressed as 7-dimensional vectors estimated from electromyograms (EMG). AIM 2: To explain how the pattern of muscle coordination satisfies the mechanical requirements of the task. A biomechanical model of the index finger will predict coordination patterns that reproduce the motions and forces observed in Aim 1 while evaluating the effects of variability in musculoskeletal parameters, and quantifying the degree of muscle redundancy. AIM 3: To validate the EMG and predicted coordination patterns by actuating the tendons of cadaveric fingers and comparing the mechanical output with the voluntary and model actions.