Radial distance determination in the rat vibrissal system and the effects of Weber's law

Solomon, Joseph H.; Hartmann, Mitra J. Z.

doi:10.1098/rstb.2011.0166

Cited by 56 publications

(63 citation statements)

References 45 publications

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“…Previous studies have suggested that the primary importance of whisker taper is that it alters the angle at which a whisker will slip off an object [22,23]. We suggest that an equally important reason is that taper is essential for producing unique mappings between mechanical signals at the whisker base and the 3D contact point [6,30].…”

Section: F Contour Extraction Using Continuous Sweeps Of the Whiskermentioning

confidence: 99%

“…A whisker's trajectory along a surface is strongly influenced by friction, texture, surface defects, and local slope: the present work offers an approach to reduce the influence of these variables for contour extraction. Rates of change in bending moment could then be used to sense object motion or object compliance [6,29,30].…”

Section: F Contour Extraction Using Continuous Sweeps Of the Whiskermentioning

confidence: 99%

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A Novel Whisker Sensor Used for 3D Contact Point Determination and Contour Extraction

Emnett¹,

Graff²,

Hartmann³

2018

Robotics: Science and Systems XIV

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Abstract-We developed a novel whisker-follicle sensor that measures three mechanical signals at the whisker base. The first two signals are closely related to the two bending moments, and the third is an approximation to the axial force. Previous simulation studies have shown that these three signals are sufficient to determine the three-dimensional (3D) location at which the whisker makes contact with an object. Here we demonstrate hardware implementation of 3D contact point determination and then use continuous sweeps of the whisker to show proof-of principle 3D contour extraction. We begin by using simulations to confirm the uniqueness of the mapping between the mechanical signals at the whisker base and the 3D contact point location for the specific dimensions of the hardware whisker. Multi-output random forest regression is then used to predict the contact point locations of objects based on observed mechanical signals. When calibrated to the simulated data, signals from the hardware whisker can correctly predict contact point locations to within 1.5 cm about 74% of the time. However, if normalized output voltages from the hardware whiskers are used to train the algorithm (without calibrating to simulation), predictions improve to within 1.5 cm for about 96% of contact points and to within 0.6 cm for about 78% of contact points. This improvement suggests that as long as three appropriate predictor signals are chosen, calibrating to simulations may not be required. The sensor was next used to perform contour extraction on a cylinder and a cone. We show that basic contour extraction can be obtained with just two sweeps of the sensor. With further sweeps, it is expected that full 3D shape reconstruction could be achieved.

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Section: F Contour Extraction Using Continuous Sweeps Of the Whiskermentioning

confidence: 99%

Section: F Contour Extraction Using Continuous Sweeps Of the Whiskermentioning

confidence: 99%

A Novel Whisker Sensor Used for 3D Contact Point Determination and Contour Extraction

Emnett¹,

Graff²,

Hartmann³

2018

Robotics: Science and Systems XIV

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“…Under these two conditions, a tapering antenna will produce very different curvature profiles along its length, thus mechanically simplifying discrimination of stimuli. Interestingly, tapering in rat whiskers can improve the reliability of information during slower feature extraction tasks Pammer et al, 2013;Solomon and Hartmann, 2011;Williams and Kramer, 2010), and we suspect that similar principles apply to exploratory object localization with antennae. Using the physical model with tunable flexural stiffness, we found that the preview distance was longer for a decreasing stiffness compared with a constant stiffness profile (Fig.…”

Section: Research Articlementioning

confidence: 99%

Mechanical processing via passive dynamic properties of the cockroach antenna can facilitate control during rapid running

Mongeau

Demir

Dallmann

et al. 2014

Journal of Experimental Biology

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The integration of information from dynamic sensory structures operating on a moving body is a challenge for locomoting animals and engineers seeking to design agile robots. As a tactile sensor is a physical linkage mediating mechanical interactions between body and environment, mechanical tuning of the sensor is critical for effective control. We determined the open-loop dynamics of a tactile sensor, specifically the antenna of the American cockroach, Periplaneta americana, an animal that escapes predators by using its antennae during rapid closed-loop tactilely mediated course control. Geometrical measurements and static bending experiments revealed an exponentially decreasing flexural stiffness (EI) from base to tip. Quasi-static experiments with a physical model support the hypothesis that a proximodistally decreasing EI can simplify control by increasing preview distance and allowing effective mapping to a putative control variable -body-to-wall distance -compared with an antenna with constant EI. We measured the free response at the tip of the antenna following step deflections and determined that the antenna rapidly damps large deflections: over 90% of the perturbation is rejected within the first cycle, corresponding to almost one stride period during high-speed running (~50 ms). An impulse-like perturbation near the tip revealed dynamics that were characteristic of an inelastic collision, keeping the antenna in contact with an object after impact. We contend that proximodistally decreasing stiffness, high damping and inelasticity simplify control during high-speed tactile tasks by increasing preview distance, providing a one-dimensional map between antennal bending and body-to-wall distance, and increasing the reliability of tactile information.

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“…the distance from the base of the whisker shaft to where it was deflected against the surface). In their contribution, Solomon & Hartmann [39] survey a number of different methods that could be applied to compute radial distance based on whisker bending as detected at the base of the whisker within the follicle. A general principle in psychophysics, owing to the experimental psychologist Ernst Weber, is that the 'just noticeable difference' in the change in the magnitude of a stimulus is proportional to the size of the initial stimulus.…”

Section: Contents Of Theme Issuementioning

confidence: 99%

Active touch sensing

Prescott

Diamond

Wing

2011

Phil. Trans. R. Soc. B

204

146

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Active sensing systems are purposive and information-seeking sensory systems. Active sensing usually entails sensor movement, but more fundamentally, it involves control of the sensor apparatus, in whatever manner best suits the task, so as to maximize information gain. In animals, active sensing is perhaps most evident in the modality of touch. In this theme issue, we look at active touch across a broad range of species from insects, terrestrial and marine mammals, through to humans. In addition to analysing natural touch, we also consider how engineering is beginning to exploit physical analogues of these biological systems so as to endow robots with rich tactile sensing capabilities. The different contributions show not only the varieties of active touch-antennae, whiskers and fingertips-but also their commonalities. They explore how active touch sensing has evolved in different animal lineages, how it serves to provide rapid and reliable cues for controlling ongoing behaviour, and even how it can disintegrate when our brains begin to fail. They demonstrate that research on active touch offers a means both to understand this essential and primary sensory modality, and to investigate how animals, including man, combine movement with sensing so as to make sense of, and act effectively in, the world.

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Radial distance determination in the rat vibrissal system and the effects of Weber's law

Cited by 56 publications

References 45 publications

A Novel Whisker Sensor Used for 3D Contact Point Determination and Contour Extraction

A Novel Whisker Sensor Used for 3D Contact Point Determination and Contour Extraction

Mechanical processing via passive dynamic properties of the cockroach antenna can facilitate control during rapid running

Active touch sensing

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