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

Abstract

Despite the increased interest in exoskeleton research in the last decades, not much progress has been made on the successful reduction of user effort. In humans, biarticular elements have been identified as one of the reasons for the energy economy of locomotion. This document gives an extensive literature overview concerning the function of biarticular muscles 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 find an answer on the question whether the biarticular property leads to a unique contribution to energy efficiency of locomotion, 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.

Biarticular muscles in light of template models, experiments and robotics: a review

“…4 Here, we mainly consider relevant studies since 2017. Please refer to earlier works in the review of Junius et al [13].…”

From a biological template model to gait assistance with an exosuit

“…In addition to ability of measuring the 59 load (e.g., body weight) in humans, high dependency of compensatory leg muscle 60 activation was demonstrated experimentally [41]. 61 Facilitating control with compliant biarticular actuators: Studies on 62 biomechanics of human gaits and robotics show that biarticular muscles help to 63 generate motions in a more energy efficient way [34,42]. In fact, these muscles actuate 64 two joints simultaneously, transfer the energy towards distal joints and further control 65 the output force direction [34,43], [35].…”

“…61 Facilitating control with compliant biarticular actuators: Studies on 62 biomechanics of human gaits and robotics show that biarticular muscles help to 63 generate motions in a more energy efficient way [34,42]. In fact, these muscles actuate 64 two joints simultaneously, transfer the energy towards distal joints and further control 65 the output force direction [34,43], [35]. Given these features, biarticular assistive devices 66 can be more effective in reducing energy consumption during walking.…”

3D computational models explain muscle activation patterns and energetic functions of internal structures in fish swimming

“…Muscle is the executor of 19 the neural control and the source of mechanical power in fish swimming. Therefore, 20 how muscles are used is a key question in understanding the control and mechanics of 21 fish swimming and has been under multidisciplinary research over the past decades. 22 Experimentally, muscle activation during swimming is measured using 23 electromyography (EMG) for various fish species [1][2][3][4][5] (Fig 1).…”

“…While local elasticity can transfer energy temporally, the spatial transmission of 278 energy can only be achieved by other structures. In animals, coupled joint articulation 279 by tendons over two or more joints is common and is an effective structure to save and 280 transfer energy [21]. For carangiform swimmers, long tendons exist that span over 281 many vertebra [22].…”