@article{Babic2009,

title = {A Biarticulated Robotic Leg for Jumping Movements: Theory and Experiments},

author = {Jan Babi\v{c} and Bokman Lim and Damir Omr\v{c}en and Jadran Lenar\v{c}i\v{c} and Frank C Park},

url = {http://mechanismsrobotics.asmedigitalcollection.asme.org/article.aspx?articleid=1484860},

doi = {10.1115/1.2963028},

issn = {19424302},

year  = {2009},

date = {2009-01-01},

journal = {Journal of Mechanisms and Robotics},

volume = {1},

number = {1},

pages = {011013},

abstract = {This paper investigates the extent to which biarticular actuation mechanisms\textemdashspring-driven redundant actuation schemes that extend over two joints, similar in function to biarticular muscles found in legged animals\textemdashimprove the performance of jumping and other fast explosive robot movements. Robust numerical optimization algorithms that take into account the complex dynamics of both the redundantly actuated system and frictional contact forces are developed. We then quantitatively evaluate the gains in vertical jumping vis-\`{a}-vis monoarticular and biarticular joint actuation schemes and examine the effects of spring stiffness and activation angle on overall jump performance. Both numerical simulations and experiments with a hardware prototype of a biarticular legged robot are reported.},

keywords = {Biarticular Muscle, Dynamic Motion, Robot Design},

pubstate = {published},

tppubtype = {article}

}

@article{Babic2006,

title = {Optimization of biarticular gastrocnemious muscle in humanoid jumping robot simulation},

author = {Jan Babi\v{c} and Jadran Lenar\v{c}i\v{c}},

url = {http://www.worldscientific.com/doi/abs/10.1142/S0219843606000722},

doi = {10.1142/S0219843606000722},

issn = {0219-8436},

year  = {2006},

date = {2006-01-01},

journal = {International Journal of Humanoid Robotics},

volume = {3},

number = {2},

pages = {219--234},

abstract = {We propose a new human inspired structure of the lower extremity mechanism by which a humanoid robot will be able to efficiently perform fast movements such as running and jumping. We build a dynamic model of the humanoid robot which includes an elastic model of the biarticular muscle gastrocnemius and determine the role of the biarticular muscles and the elastic tendons in performing the vertical jump. We demonstrate that biarticular links contribute a great deal to the performance of the vertical jump. We also show that timing of the biarticular link activation and stiffness of the biarticular link influence the height of the jump considerably.},

keywords = {Biarticular Muscle, Dynamic Motion, Robot Design},

pubstate = {published},

tppubtype = {article}

}

@article{Babic2004,

title = {In vivo determination of triceps surae muscle-tendon complex viscoelastic properties},

author = {Jan Babi\v{c} and Jadran Lenar\v{c}i\v{c}},

url = {http://link.springer.com/10.1007/s00421-004-1107-4},

doi = {10.1007/s00421-004-1107-4},

issn = {1439-6319},

year  = {2004},

date = {2004-01-01},

journal = {European Journal of Applied Physiology},

volume = {92},

number = {4-5},

pages = {477--84},

abstract = {Viscoelastic properties of muscles and tendons have an important influence on human motion performance. Proper determination of these properties is essential in the analysis and modelling of human motion dynamics. The purpose of our study was to develop a method for in vivo determination of the viscoelastic properties of the entire triceps surae muscle-tendon complex (MTC) including the gastrocnemius. Ten trained male subjects participated in this study. The measurement procedure consisted of two parts: soleus and Achilles tendon stiffness and viscosity were determined in the first part while the gastrocnemius stiffness and viscosity were determined in the second part. The measurement device and the procedure have been designed in such a manner that as few human body segments move as possible during the measurement. Thus, the measurement uncertainty due to the approximation of the properties of the human body segments was minimized. Triceps surae MTC viscoelastic properties of both legs were measured for each subject. There were no significant differences in viscoelastic coefficients for left and right lower extremities; however, there were noticeable differences between subjects. The soleus stiffness coefficient was greater than the gastrocnemius stiffness coefficient by 87.6 m(-1) in average. For all subjects, soleus viscosity was equal or greater than gastrocnemius viscosity. Values of viscoelastic parameters obtained by our method can be used in the analysis and modelling of human movement in situations where the knee joint is not necessarily flexed and there is coactivation of the soleus and the gastrocnemius.},

keywords = {Biarticular Muscle, Muscle Mechanics, Neuromusculoskeletal Modelling},

pubstate = {published},

tppubtype = {article}

}