Biarticular elements as a contributor to energy efficiency: biomechanical review and application in bio-inspired robotics

Despite the increased interest in exoskeleton research over the last
decades, not much progress has been made on the successful reduction of
user effort. In humans, biarticular elements have been identied as one of
the reasons for the energy economy of locomotion. This document gives an
extensive literature overview concerning the function of biarticular mus-
cles in human beings. The exact role of these muscles in the efficiency
of human locomotion is reduced to three elementary functions: energy
transfer towards distal joints, efficient control of output force direction
and double joint actuation. This information is used to give an insight in
the application of biarticular elements in bio-inspired robotics, i.e. bipedal
robots, exoskeletons, robotic manipulators and prostheses. Additionally
an attempt is made to nd an answer on the question whether the biar-
ticular property leads to a unique contribution to energy efficiency of lo-
comotion, unachievable by mono-articular alternatives. This knowledge is
then further utilised to indicate how biarticular actuation of exoskeletons
can contribute to an increased performance in reducing user effort.