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Séminaire impromptu - Gerald LoebUnderstanding Haptics by Building Computational and Physical Models

Abstract :

The human hand provides an existence proof that dexterity is possible even as mechatronic systems remain far from such capabilities. It teaches us that hand function in daily life depends on the integration of command signals and contingency plans that anticipate the mechanical dynamics of the limb and its interaction with objects. Conversely, every interaction between the hand and an object provides a wealth of sensory information that is used to update prior hypotheses about the properties and identity of that object and then to select an even better set of command signals and contingency plans to achieve the desired function. Unfortunately, there are no suitable methods to study the neural computation that underlies these capabilities in humans, and dexterous behaviors are limited, difficult to train and difficult to measure in experimental animals. This has led us to develop and test theories of sensorimotor control using computational and mechatronic machines to see if we can replicate biological behaviors. I will review three such models that have generated results that are scientifically interesting and potentially useful:

· A computational model representing the intrinsic mechanical and energetic properties of a two-joint, six-muscle arm plus proprioceptors and spinal interneuronal networks was able to generate the complex coordination required to perform voluntary reaches. Higher motor centers may learn to take advantage of this rather than computing and controlling motor programs directly.

· A compliant fingertip with a contact sensor and spinal-reflex-like control loops greatly improved the usability of a myoelectric prosthetic hand, a form of telerobot.

·A biomimetic tactile sensor combined with a Bayesian algorithm for deciding on exploratory movements outperformed humans in identifying materials based on their surface textures.

Selected publications

Last publications

Are muscle synergies useful for neural control?

de Rugy A, Loeb GE, Carroll TJ.
Front Comput Neurosci. 2013 Mar 21;7:19. doi: 10.3389/fncom.2013.00019. eCollection 2013.

Percutaneously injectable fetal pacemaker: electrodes, mechanical design and implantation.
Zhou L, Chmait R, Bar-Cohen Y, Peck RA, Loeb GE.
Conf Proc IEEE Eng Med Biol Soc. 2012;2012:6600-3. doi: 10.1109/EMBC.2012.6347507.

Percutaneously injectable fetal pacemaker: electronics, pacing thresholds, and power budget.
Nicholson A, Chmait R, Bar-Cohen Y, Zheng K, Loeb GE.
Conf Proc IEEE Eng Med Biol Soc. 2012;2012:5730-3. doi: 10.1109/EMBC.2012.6347296.

Estimation of excitatory drive from sparse motoneuron sampling.
Li Y, Smith LH, Hargrove LJ, Weber DJ, Loeb GE.
Conf Proc IEEE Eng Med Biol Soc. 2012;2012:3628-31. doi: 10.1109/EMBC.2012.6346752.

Sparse optimal motor estimation (SOME) for extracting commands for prosthetic limbs.
Li Y, Smith LH, Hargrove LJ, Weber DJ, Loeb GE.
IEEE Trans Neural Syst Rehabil Eng. 2013 Jan;21(1):104-11. doi: 10.1109/TNSRE.2012.2218286. Epub 2012 Sep 27.

Scientific focus :

Background. Dr. Loeb was born in New Brunswick , NJ , received his B.A. ('69) and M.D. ('72) from Johns Hopkins University , and trained in surgery at the University of Arizona . He spent 15 years in the Laboratory of Neural Control at the National Institutes of Health and 12 years at Queen's University where he was Professor of Physiology and Director of the Bio-Medical Engineering Unit. He served as Chief Scientist (consulting) for Advanced Bionics Corp. of Sylmar , California , from 1994-1999. Dr. Loeb joined USC in September, 1999. He has published over 250 journal articles and chapters, a book on electromyography, and holds 58 patents.

Dr. Loeb works on neural prosthetics - interfaces between electronic devices and the nervous system that are used to replace sensory and motor functions and correct dysfunctions in people with neurological problems. He was one of the developers of the cochlear implant now used to restore functional hearing to the deaf and continues to pursue improvements in this mature technology. His research group developed BIONs - BIOnic Neurons that are small enough to be injected into paralyzed muscles where they receive power and send and receive data by radio links with an external controller. In addition to developing and testing technology, Dr. Loeb has been active in basic neurophysiological studies of the sensorimotor nervous system in order to understand normal biological control. Computer models based on experimental data from muscles, motoneurons and proprioceptors are being developed to test new theories of control that may permit the reanimation of paralyzed limbs via functional electrical stimulation ( FES ). Similar models and interfaces are also being applied to the design and control of powered prosthetic arms and hands.  Details of these projects and complete recent reports can be found at Dr. Loeb is also an inventor of the BioTac ®, a biomimetic tactile sensing system being commercialized by Syntouch LLC, for which he is Chief Executive Officer ( SynTouch was designated a Technology Pioneer for 2014 by the World Economic Forum.


Gerald Loeb est connu mondialement pour sa contribution au développement de l’implant cochléaire, et pour ses recherches fondamentales sur le contrôle sensorimoteur dont il applique les principes au contrôle des neuroprothèses. Il parlera de ces travaux sur la modélisation des réseaux spinaux et l’exploitation de leur capacité d’intégration pour des contrôleurs artificiels, ainsi que le capteur tactile biomimétique et les réflexes associés que son équipe développe pour redonner le sens du toucher aux prothèses de main.

Gerald Loeb sera disponible après son talk pour discuter avec ceux qui le souhaitent – ci c’est votre cas merci de me le faire savoir .


Aymar de Rugy