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A pencil balancing robot using a pair of AER dynamic vision sensors


Conradt, J; Cook, M; Berner, R; Lichtsteiner, P; Douglas, R J; Delbruck, T (2009). A pencil balancing robot using a pair of AER dynamic vision sensors. In: IEEE International Symposium on Circuits and Systems, 2009 (ISCAS 2009), Taipei, Taiwan, 24 May 2009 - 27 May 2009, 781-784.

Abstract

Balancing a normal pencil on its tip requires rapid feedback control with latencies on the order of milliseconds. This demonstration shows how a pair of spike-based silicon retina dynamic vision sensors (DVS) is used to provide fast visual feedback for controlling an actuated table to balance an ordinary pencil. Two DVSs view the pencil from right angles. Movements of the pencil cause spike address-events (AEs) to be emitted from the DVSs. These AEs are transmitted to a PC over USB interfaces and are processed procedurally in real time. The PC updates its estimate of the pencil's location and angle in 3d space upon each incoming AE, applying a novel tracking method based on spike-driven fitting to a model of the vertical shape of the pencil. A PD-controller adjusts X-Y-position and velocity of the table to maintain the pencil balanced upright. The controller also minimizes the deviation of the pencil's base from the center of the table. The actuated table is built using ordinary high-speed hobby servos which have been modified to obtain feedback from linear position encoders via a microcontroller. Our system can balance any small, thin object such as a pencil, pen, chop-stick, or rod for many minutes. Balancing is only possible when incoming AEs are processed as they arrive from the sensors, typically at intervals below millisecond ranges. Controlling at normal image sensor sample rates (e.g. 60 Hz) results in too long latencies for a stable control loop.

Balancing a normal pencil on its tip requires rapid feedback control with latencies on the order of milliseconds. This demonstration shows how a pair of spike-based silicon retina dynamic vision sensors (DVS) is used to provide fast visual feedback for controlling an actuated table to balance an ordinary pencil. Two DVSs view the pencil from right angles. Movements of the pencil cause spike address-events (AEs) to be emitted from the DVSs. These AEs are transmitted to a PC over USB interfaces and are processed procedurally in real time. The PC updates its estimate of the pencil's location and angle in 3d space upon each incoming AE, applying a novel tracking method based on spike-driven fitting to a model of the vertical shape of the pencil. A PD-controller adjusts X-Y-position and velocity of the table to maintain the pencil balanced upright. The controller also minimizes the deviation of the pencil's base from the center of the table. The actuated table is built using ordinary high-speed hobby servos which have been modified to obtain feedback from linear position encoders via a microcontroller. Our system can balance any small, thin object such as a pencil, pen, chop-stick, or rod for many minutes. Balancing is only possible when incoming AEs are processed as they arrive from the sensors, typically at intervals below millisecond ranges. Controlling at normal image sensor sample rates (e.g. 60 Hz) results in too long latencies for a stable control loop.

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21 citations in Scopus®
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Additional indexing

Item Type:Conference or Workshop Item (Speech), refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Neuroinformatics
Dewey Decimal Classification:570 Life sciences; biology
Language:English
Event End Date:27 May 2009
Deposited On:13 Mar 2010 10:22
Last Modified:05 Apr 2016 13:59
ISBN:978-1-4244-3827-3
Additional Information:© 2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Free access at:Related URL. An embargo period may apply.
Publisher DOI:https://doi.org/10.1109/ISCAS.2009.5117867
Related URLs:http://conf.ncku.edu.tw/iscas2009/
http://ieeexplore.ieee.org
http://www.ini.uzh.ch/node/24029
Permanent URL: https://doi.org/10.5167/uzh-31959

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