The effect of whisker movement on radial distance estimation: a case study in comparative robotics

Abstract

Whisker movement has been shown to be under active control in certain specialist animals such as rats and mice. Though this whisker movement is well characterized, the role and effect of this movement on subsequent sensing is poorly understood. One method for investigating this phenomena is to generate artificial whisker deflections with robotic hardware under different movement conditions. A limitation of this approach is that assumptions must be made in the design of any artificial whisker actuators, which will impose certain restrictions on the whisker-object interaction. In this paper we present three robotic whisker platforms, each with different mechanical whisker properties and actuation mechanisms. A feature-based classifier is used to simultaneously discriminate radial distance to contact and contact speed for the first time. We show that whisker-object contact speed predictably affects deflection magnitudes, invariant of whisker material or whisker movement trajectory. We propose that rodent whisker control allows the animal to improve sensing accuracy by regulating contact speed induced touch-to-touch variability.

Tactile Superresolution and Biomimetic Hyperacuity

“…This combination of tactile sensor with a Cartesian robot has been employed previously for testing various tactile sensors, including tactile vibrissae [24], [25] and tactile fingertips [11]- [14], [26]. The Cartesian robot has the benefit that it can precisely and repeatedly position the sensor in two dimensions (absolute repeatability 0.02 mm).…”

Biomimetic Active Touch with Fingertips and Whiskers

“…1b) is mounted as an end effector on a two degree-of-freedom Cartesian robot (2axis PXYx, Yamaha Robotics). This combination of tactile sensor with Cartesian robot has been employed previously for testing various sensors, including tactile vibrissae [46], [47] and tactile fingertips [10], [29], [48], [49]. The Cartesian robot is able to precisely and repeatedly position the sensor in two dimensions (absolute repeatability 0.02 mm) with simple control, making it a good platform to probe tactile sensing in basic one-dimensional scenarios with contacts controlled in the other dimension.…”

“…The choice of experiments was governed partly by availability of data from previous studies and partly by wanting to consider a wide variety of types of contact data. Both whisker experiments have been considered previously, but only using passive methods for perception [46], [47], [62]. One cylinder of the first data set for the TacTip and iCub fingertips has been considered before [6], [7], but the analysis was restricted to perception of contact location, not stimulus identity, in studies of tactile superresolution of location.…”

Active contour following to explore object shape with robot touch

“…A Cartesian robot (Yamaha XY-X series) and a Mindstorms NXT Lego robot were integrated to achieve movements in the x-, y-and z-axes (Figure 2). The Cartesian robot allows precise positioning movements along the x-and y-axes to an accuracy of about 20 µm, and has been previously utilized for characterising the properties of tactile sensors, for example whiskers [19,20]. Given the physical characteristics of the tactile sensor (in that it could be damaged by rubbing repeatedly along a surface), a tapping procedure was chosen for gathering sensory data.…”