The introduction of impedance control in 1985 by Neville Hogan paved the way for a safe, gentle and effective interaction between humans and machines. This interaction is ideal for rehabilitation and is epitomized in the design of manipulanda that pioneered clinical and neurological applications, the most prominent being the MIT-MANUS, developed by Hermano Igo Krebs. Following this line of research, we have recently introduced the MIT's pediatric Anklebot, an adaptive robotic device that provides an “assist-as-needed” therapy and targets ankle movements in children with neurological disorders (Michmizos et al. 2015). Since 2012, the rehabilitation robot has been used successfully in pilot studies in Pediatric Hospitals in the USA and Europe.
To design the robot and its rehabilitation games, we considered the needs and special characteristics of children with cognitive and perceptual deficiencies that accompany motor disorders. We researched on whether the sensorimotor control of the upper extremities generalizes, and to what extent, to the lower extremities. Macroscopically, we demonstrated the adequacy of Fitts's law to predict the ankle performance in ankle movements (Michmizos & Krebs 2014a); this study verified that the central nervous system controls the speed and accuracy of ankle movement in the same way as in upper extremities. Mesoscopically, we found a remarkable similarity between the models that describe the speed profiles of ankle pointing movements and the ones for the upper extremities (Michmizos et al. 2014). Microscopically, we found that the reaction time for the ankle movements increased with the number of stimuli at an equal pace, as would be predicted by Hick-Hyman law in hand movements. Interestingly, we found evidence that there are differences in ankle muscle innervations that affect reaction time (Michmizos & Krebs 2014b).
Click on the CBS News link to watch a story on how our robot helped a young stroke victim reclaim his future.
H.I. Krebs, K.P. Michmizos, T. Susko, H. Lee, A. Roy, N. Hogan, "Beyond Human or Robot Administered Treadmill Training," (pp. 409-433) in D.J. Reinkensmeyer, V. Dietz (eds.): Neurorehabilitation Technology, Springer, 2016 [ link ]
K.P. Michmizos, S. Rossi, P. Cappa, H.I. Krebs, "Robot-Aided Neurorehabilitation: A Pediatric Robot for Ankle Rehabilitation," IEEE Transactions on Neural Systems and Rehabilitation Engineering, 23(6), pp. 1056 - 1067, doi: 10.1109/TNSRE.2015.2410773, 2015 [ link ]
K.P. Michmizos, L. Vaisman, H.I. Krebs, "A Comparative analysis of speed profile models for ankle pointing movements: Evidence that lower and upper extremity discrete movements are controlled by a single invariant strategy," Frontiers in Human Neuroscience, 2014 [ link ]
K.P. Michmizos, H.I. Krebs, "Reaction time in ankle movements: a diffusion model analysis," Experimental Brain Research , 232(11), pp. 3475-88, 2014b [ link ]
K.P. Michmizos, H.I. Krebs, "Pointing with the ankle: the speed-accuracy tradeoff," Experimental Brain Research, 232(2), pp. 647-657, 2014a [ link ]