Haptic Perceptual Instruments

触觉感知是指通过身体内的传感器对身体及其附属物的感知。这个术语包含了通常所说的“触摸”以及其他含义。例如，在没有视力的情况下，一个人可以意识到自己四肢的位置，也可以通过挥舞和举起物体来确定物体的属性（例如，重量，长度）。触觉感知的这些方面被称为动态触觉，它们的基础是感知肌肉和肌腱状态的受体。视觉和听觉对日常活动的重要性是显而易见的，与之不同的是，触觉感知系统对我们日常感知和行动的贡献是非常微妙的。失去触觉（没有伴随瘫痪）是极其罕见的，这一事实开始说明触觉在日常活动中的基本重要性，比如举起杯子、用笔、指着一个单词，或者只是站直。我们的研究是针对动态触摸和它在日常控制操作中所起的作用的理解。我们问，它能做什么？它是怎么做到的？迄今为止的研究表明，肢体运动的旋转动力学是这两个问题的主要限制，这是在拟议的研究中所追求的。形式上，动态触摸的成就与惯性张量（量化物体对旋转的阻力）和姿态旋量（量化物体相对于某些参考系（如手）的方向）有关。在一些基本的方法中，参与者使用一个看不见的物体（其结构被特别设计以产生实验相关的惯性张量或姿态旋量）来感知它的长度、宽度、形状、重量或方向。在其他基本方法中，参与者试图将不可见的上肢或肢体部分（带有系统控制肢体惯性张量和姿态旋量的附加夹板）定向到环境目标或另一个不可见的肢体。一个主要的论点是，在动态触摸感知中，与手相关的触觉子系统表现为智能工具：它利用物理的、基于规律的不变量。设计实验是为了检验不同的注意力需求（以及不同特性在感知上独立的程度）、不同的力结构（如在水下和旋转的空间站中所经历的）和不同的神经条件（如当肌腱被电磁振动时产生的虚假受体状态）的后果。理解控制动态触摸的原理将丰富感知系统的计算和神经建模的物理约束，并为体感障碍和假肢和机器人肢体的设计提供新的假设来源。这样的理解也可能会激发对生物感知-行动系统形成的物理原理以及利用它们的认知和神经约束的更深入的研究。该项目部分由美国国家科学基金会重大研究仪器项目资助。

Haptic perception refers to the perception one has of one's body, and of attachments to it, by means of sensors in the body. The term incorporates what is commonly meant by `touch,` and more besides. For example, without benefit of vision one is aware of the positions of one's limbs, and one can also ascertain properties of objects (e.g., weight, length)by wielding and hefting them. These aspects of haptic perception, referred to as dynamic touch, have their basis in receptors that sense the states of muscles and tendons. Unlike vision and audition, whose importance to everyday activity are obvious, the haptic perceptual system is strikingly subtle in its contribution to our everyday achievements of perceiving and acting. The fact that the loss of the sense of touch (without concomitant paralysis) is extremely rare and profoundly devastating begins to illustrate the fundamental importance of this sense in common activities such as lifting a cup, using a pen, pointing to a word, or just standing upright. Our research is directed at dynamic touch and an understanding of the role it plays in everyday controlled manipulations. We ask, What can it do?; and, How does it do it? Research to date has implicated the rotational dynamics of limb movements as the major constraint on both of these questions, and this is pursued in the proposed research. Formally, the achievements of dynamic touch are related to the inertia tensor (which quantifies an object's resistance to being rotated) and the attitude spinor (which quantifies an object's orientation relative to some reference frame such as the hand). In some of the basic methodologies, participants wield an unseen object (whose structure has been specially contrived to produce the experimentally relevant inertia tensor or attitude spinor) to perceive its length, width, shape, weight, or orientation to the hand. In other basic methodologies, the participants attempt to orient a nonvisible upper limb or limb segment (with attached splints that systematically control the limb's inertia tensor and attitude spinor) to an environmental target or to another nonvisible limb. A major thesis is that, in perception by dynamic touch, the hand-related haptic subsystem behaves as a smart instrument: It capitalizes on physical, law-based, invariants. Experiments are designed to examine the consequences of different attentional demands (and the extent to which different properties are perceptually independent), different force structures (such as those experienced underwater and in rotating space stations), and in different neural conditions (such as the spurious receptor states produced when the tendons are vibrated electromagnetically). Understanding the principles governing dynamic touch should enrich the physical constraints on computational and neural modeling of perceptual systems and provide a source of new hypotheses about somatosensory disorders and about designs for prosthetic and robot limbs. Such understanding might also be expected to motivate more intensive study of the physical principles formative of biological perception-action systems and of the cognitive and neural constraints that exploit them. s partly supported by the NSF Major Research Instrumentation Program.