Simulation-based biomechanical assessment of unpowered exoskeletons for running

Abstract

Due to the complexity and high degrees of freedom, the detailed assessment of human biomechanics is necessary for the design and optimization of an effective exoskeleton. In this paper, we present full kinematics, dynamics, and biomechanics assessment of unpowered exoskeleton augmentation for human running gait. To do so, the considered case study is the assistive torque profile of I-RUN. Our approach is using some extensive data-driven OpenSim simulation results employing a generic lower limb model with 92-muscles and 29-DOF. In the simulation, it is observed that exoskeleton augmentation leads to $$4.62\%$$ 4.62 % metabolic rate reduction for the stiffness coefficient of $$\alpha ^*=0.6$$ α ∗ = 0.6 . Moreover, this optimum stiffness coefficient minimizes the biological hip moment by $$26\%$$ 26 % . The optimum stiffness coefficient ($$\alpha ^*=0.6$$ α ∗ = 0.6 ) also reduces the average force of four major hip muscles, i.e., Psoas, Gluteus Maximus, Rectus Femoris, and Semimembranosus. The effect of assistive torque profile on the muscles’ fatigue is also studied. Interestingly, it is observed that at $$\alpha ^{\#}=0.8$$ α # = 0.8 , both all 92 lower limb muscles’ fatigue and two hip major mono-articular muscles’ fatigue have the maximum reduction. This result re-confirm our hypothesis that ”reducing the forces of two antagonistic mono-articular muscles is sufficient for involved muscles’ total fatigue reduction.” Finally, the relation between the amount of metabolic rate reduction and kinematics of hip joint is examined carefully where for the first time, we present a reliable kinematic index for prediction of the metabolic rate reduction by I-RUN augmentation. This index not only explains individual differences in metabolic rate reduction but also provides a quantitative measure for training the subjects to maximize their benefits from I-RUN.

A Framework for Modeling, Optimization, and Musculoskeletal Simulation of an Elbow–Wrist Exosuit

“…While extensive research exists on the design and optimization of lower-limb exoskeletons utilizing musculoskeletal simulations [18][19][20][21], limited attention has been given to the development and optimization of exosuits, especially for the upper limbs [22][23][24][25][26][27]. Currently, there is a notable absence of quantitative models and optimization techniques for the creation of soft upper-limb exosuits and their examination concerning human biomechanics via musculoskeletal simulations.…”

An Adaptive Assistance Controller to Optimize the Exoskeleton Contribution in Rehabilitation

“…For instance, Nasiri et al [28] introduced a general adaptation rule to optimize the robotic assistive torque which minimizes the actuator torque. This adaptation rule is extended for wearable robots in [29,30] and its generality for lower limb exoskeletons is studied in [31]. However, in SCI individuals, the muscles' EMG signals are not sufficiently reliable for controller adaptation.…”