Rakesh Gosangi PRISM lab Department of Computer Science and Engineering Texas A&M University
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Transcript of Rakesh Gosangi PRISM lab Department of Computer Science and Engineering Texas A&M University
Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch
Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Rakesh GosangiPRISM lab
Department of Computer Science and Engineering
Texas A&M University
Outline
• Introduction• Rat’s vibrissal system• Neural Processing• Whisking Robots• Discussion and Future
Introduction
• Mammals do a large part of their tactile sensing using vibrissae (whiskers)
• Modern robotics fail to match the capabilities of mammals in tactile perception
Tactile perception in animals
• Alerting stimulus to produce motor response
• Perform complex perceptual tasks like– Determine shape, texture, position of objects in 3-D
space
• Guide motion for nocturnal species like rats and cockroaches
Image – common rat (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Tactile perception in animals
• Etruscan shrew prey capture is guided by tactile cues
• Seals can detect hydrodynamic trails left by fish with their whiskers
Images – water shrew, harbor seal (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Tactile Sensors in robotics
• The least trusted sensors– Used as a last line of defense when all the other sensing
modalities fail
• Passive in nature– Waiting to be deflected by an object
Outline
• Introduction• Rat’s vibrissal system• Neural Processing• Whisking Robots• Discussion and Future
Rat’s vibrissal system
• Long facial whiskers called macrovibrissae– Individually actuated and actively controlled by the rats
• Shorter, densely packed microvibrissae on chin and lips– Non actuated
• Mechanoreceptors in the hair follicles convert direction, velocity, duration and torque of whisker movements into electrophysiological signals
Use of macro and micro vibrissae
Image – Use of macro and micro vibrissae (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Whisking movements
• Macro vibrissae are moved back and forth (whisking) at high speeds (5-25/sec)
• The movement of the whiskers is controlled depending on head-body movement, recent sensory experience
Movement of whiskers of a head-restrained rat
Image – Whisking control in rat (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Whisking movements
• Whiskers move asymmetrically when the rat turns its head
• Rats can control the speed of the individualwhiskers
• Whiskers have many degrees of freedom– Parallel and perpendicular to the plane of the head– Torsional rotation
Image – Asymmetry in whisking movements (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Outline
• Introduction• Rat’s vibrissal system• Neural Processing• Whisking Robots• Discussion and Future
Neural Processing
• Whisker deflections are converted into physiological signals.
• These signals are processed in the thalamus and sensory cortex
• There exists a one-to-one mapping between the whiskers and barrels inthe sensory cortex
Image – Vibrissal sensory processing pathway (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Outline
• Introduction• Rat’s vibrissal system• Neural Processing• Whisking Robots• Discussion and Future
Whisking Robots
• Sensor transduction– Potentiometers – to measure torque– Electret microphones
• Sensitive to deflection but cannot detect direction– Piezoelectric sensors
• Cannot measure static deflections– Magnetic Hall-effect sensors
• Robust, lightweight and sensitive
Whisking Robots
• Actuation– Independently actuated whiskers– Uniform actuation of whiskers
• Mechanical properties of the vibrissal shaft– Steel wires– Molded composites
• Morphed like rat whiskers
• Signal processing– Neuromorphic algorithms
aMouse
• Rat whiskers were glued to electret microphones• ANNs and spectral analysis for signal processing
Image – aMouse (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Whisking sensobot
• 4x1 array of whiskers with strain gauges– Extract radial distance– Estimate 3-D object shape
Image – Whisking sensobot (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Darwin IX
• Whiskers detect deformation along their length• Employed neuromorphic computational methods
– Texture discrimination
Image – Darwin IX (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Whiskerbot
• Orienting to the detectedtargets
Image – Whikserbot (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Scratchbot
• Increased degrees of freedom for moving and positioning the whiskers
• Including a neck with three degrees of freedom• Hall-effect sensors
Image – Scratchbot (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
BIOTACT
• Modular vibrissal sensing units to be assembled into different configurations
Image – Biotact (borrowed from - Whisking with Robots – From Rat Vibrissae to Biomimetic Technology for Active Touch - Tony J. Prescott, Martin J. Pearson, Ben Mitchinson, J. Charles W. Sullivan, and Anthony G. PipeIEEE Robotics & Automation – September 2009.
Outline
• Introduction• Rat’s vibrissal system• Neural Processing• Whisking Robots• Discussion and Future
Discussion
• Tactile sensing based navigation is useful in visually occluded environments
• Also useful in texture and shape recognition
• Construction of 3-D tactile maps of the environment
• The transducers (receptors) are away from contact surface– No damage due to direct physical contact
Challenges
• Better understanding of sensory motor loops in the vibrissal systems of mammals
• Biomimetic algorithms for whisker control and processing vibrissal signals
• Mapping whisker deflection signals to surface and shape properties
Questions / Comments