Eigenvectors of the inertia tensor and perceiving the orientation of a hand-held object by dynamic touch

Pagano, Christopher C.; Turvey, M. T.

doi:10.3758/bf03211699

Cited by 61 publications

(26 citation statements)

References 13 publications

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“…The correlation between perceived partial length and perceived whole length is .77, but when the relationship to In and I y z is removed, this drops to a non-GENERAL DISCUSSION A developing account ofperception by dynamic touch asserts that Ii} underlies the perception ofpersistent properties of objects such as their magnitudes and directions (both relative to the environment and relative to the perceiver). In particular, properties having to do with magnitudes (e.g., length, Fitzpatrick et al, 1994;heaviness, Amazeen & Turvey, 1996;shape, Burton, Turvey, & Solomon, 1990; map onto the principal moments of Ii}' whereas properties having to do with direction (e.g., object orientation, Pagano & Turvey, 1992;grip location, Pagano et al, 1994;limb orientation, Pagano & Turvey, 1995) map onto principal directions or eigenvectors of Iii' Although it has been well established that whole length and partial length can be perceived by dynamic touch, the original decomposition hypothesis did not exploit rotational dynamics fully. The present experiments, in recognizing that partial length is a magnitude in a direction, have revealed the tensorial basis to this instance of selective haptic perception.…”

Section: Resultsmentioning

confidence: 99%

“…An examination of Equation 4 together with Figure 1 illustrates this point. (We note that objects with different kinds of symmetries may have more than one nonzero product; see, e.g., Pagano & Turvey, 1992;Turvey, Burton, Pagano, Solomon, & Runeson, 1992). Pagano et al (1994;see also Turvey & Carello, 1995) speculated that early investigations of perceived partial length, in focusing only on IXX> had not fully exploited I ij .…”

Section: (6)mentioning

confidence: 99%

“…If there is not such a means, intended properties will not be separable. For example, it appears that whereas the orientation of the branch of an L can be perceived, the different orientations of two branches off the same stem cannot be distinguished (Pagano & Turvey, 1992). Although the two branches produce an asymmetry in the mass distribution that affects the perceived orientation of the whole object, the parts cannot be discerned.…”

Section: Attention In Haptic Perceptual Instrumentsmentioning

confidence: 99%

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Selective perception by dynamic touch

Carello

Santana

Burton

1996

Perception & Psychophysics

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Perceiving the length of a rod by dynamic touch is tied to the inertia tensor I i j , a quantification of its resistance to rotational acceleration. Perception of the portion extending in front of the grasp has previously been ascribed to decomposing one component of I i j by attention. The tensorial nature of dynamic touch suggests that this ability must be anchored wholly in the tensor. Three experiments show that perceived partial length is a function of two components of the tensor, one tied primarily to magnitude and the other tied primarily to direction, whereas perceived whole length is a function of a magnitude component alone. Dynamic touch is characterized in terms of a haptic perceptual instrument that softly assembles to exploit I i j differently depending on the intention, producing 1:1 maps that are appropriately scaled for each intention.Selective attention is marked by the ability to respond to a subset ofphysically and physiologically available information that is appropriate for an intention to perceive a particular stimulus dimension. The degree of"success" at attention might be construed in terms of the degree to which putatively irrelevant dimensions of information influence or interfere with the perceiver's evaluation of the requested dimension. Relatedly, the degree of interference from dimensions that are unattended can be taken as indicators of processes that must be engaged in order to perceive the attended dimension. Although the bulk of data on attention comes from vision and audition, there are examples from touch as well. For example, it has been noted (e.g., Gibson, 1966) that a person using a tool to explore a surface receives information about both the handtool contact and the tool-surface contact but generally attends to the latter.The kind of selective attention that has been demonstrated in dynamic or effortful touch will provide our focus. Gibson (1966) drew a distinction between dynamic touch, which entails muscular exertion in moving or stabilizing an object, and haptic touch, which involves the articulation of joints and limb segments. For example, grasping a rod somewhere along its length to wield or simply hold it requires muscular torque to counter the rotational forces brought about by the mass distribution of the rod. A number ofexperiments have shown that whether

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Section: Resultsmentioning

confidence: 99%

Section: (6)mentioning

confidence: 99%

Section: Attention In Haptic Perceptual Instrumentsmentioning

confidence: 99%

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Selective perception by dynamic touch

Carello

Santana

Burton

1996

Perception & Psychophysics

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“…The responses closely matched the actual orientation of the distal branch . In a more elaborate version of the same task, Pagano and Turvey (1992) presented subjects with a similar object which had two distal branches oriented at 90 • . The two branches were identical and by selectively weighting one branch or the other with an attached mass, they were able to shift the orientation of the object as perceived by subjects towards the weighted branch.…”

Section: Object Manipulation Taskmentioning

confidence: 99%

A modular planar robotic manipulandum with end-point torque control

Howard

Ingram

Wolpert

2009

Journal of Neuroscience Methods

204

156

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Robotic manipulanda are extensively used in investigation of the motor control of human arm movements. They permit the application of translational forces to the arm based on its state and can be used to probe issues ranging from mechanisms of neural control to biomechanics. However, most current designs are optimized for studying either motor learning or stiffness. Even fewer include end-point torque control which is important for the simulation of objects and the study of tool use. Here we describe a modular, general purpose, two-dimensional planar manipulandum (vBOT) primarily optimized for dynamic learning paradigms. It employs a carbon fibre arm arranged as a parallelogram which is driven by motors via timing pulleys. The design minimizes the intrinsic dynamics of the manipulandum without active compensation. A novel variant of the design (WristBOT) can apply torques at the handle using an add-on cable drive mechanism. In a second variant (StiffBOT) a more rigid arm can be substituted and zero backlash belts can be used, making the StiffBOT more suitable for the study of stiffness. The three variants can be used with custom built display rigs, mounting, and air tables. We investigated the performance of the vBOT and its variants in terms of effective end-point mass, viscosity and stiffness. Finally we present an object manipulation task using the WristBOT. This demonstrates that subjects can perceive the orientation of the principal axis of an object based on haptic feedback arising from its rotational dynamics.

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“…Another example: When we grasp a rod, is the inertia tensor of the rod (Pagano & Turvey, 1992) a property of a rod? The inertia tensor of a rod is not the property of the rod, but a property of the system of rotating-rod-around-arotation-point.…”

Section: Downloaded By [University Of Iowa Libraries] At 19:06 16 Marmentioning

confidence: 99%