Measurement and Simulation of Human Sitting and Standing Movement Biomechanics

Previous studies of robotic exoskeletons and prostheses with regenerative actuators have focused exclusively on level-ground walking applications. Here we analyzed the lower-limb joint mechanical power during stand-to-sit movements using inverse dynamic simulations to estimate the biomechanical energy available for regeneration. Nine subjects performed 20 sitting and standing movements while lower-limb kinematics and ground reaction forces were measured. Subject-specific body segment parameters were estimated using parameter identification. Joint mechanical power was calculated from net joint torques and rotational velocities and numerically integrated to determine joint biomechanical energy. The hip produced the largest peak negative mechanical power (1.8 ± 0.5 W/kg), followed by the knee (0.8 ± 0.3 W/kg) and ankle (0.2 ± 0.1 W/kg). Negative mechanical work from the hip, knee, and ankle per stand-to-sit movement were 0.35 ± 0.06 J/kg, 0.15 ± 0.08 J/kg, and 0.02 ± 0.01 J/kg, respectively. Assuming known regenerative actuator efficiencies (i.e., maximum 63%), robotic exoskeletons and prostheses could theoretically regenerate ~26 Joules of electrical energy while sitting down, compared to ~19 Joules per walking stride. Given that these regeneration performance calculations are based on healthy young adults, future research should involve seniors and/or rehabilitation patients to better estimate the biomechanical energy available for regeneration in individuals with mobility impairments.Reference:Laschowski B, Razavian RS, and McPhee J. (2020). Simulation of Stand-to-Sit Biomechanics for Design of Lower-Limb Exoskeletons and Prostheses with Energy Regeneration. bioRxiv. DOI: 10.1101/801258.

过往针对搭载再生驱动器（regenerative actuators）的机器人外骨骼（robotic exoskeletons）与义肢（prostheses）的研究，仅聚焦于平地行走场景的应用。
本研究通过逆动力学仿真（inverse dynamic simulations）分析了站坐转换（stand-to-sit）运动过程中的下肢关节机械功率，以估算可用于能量回收的生物力学能量（biomechanical energy）。
9名受试者完成了20次坐站交替动作，同时采集其下肢运动学（kinematics）数据与地面反作用力（ground reaction forces）。通过参数辨识（parameter identification）方法估算得到受试者个性化的身体节段参数。关节机械功率由关节净扭矩（net joint torques）与旋转角速度（rotational velocities）计算得到，并通过数值积分（numerical integration）求解得到关节生物力学能量。
髋关节的峰值负机械功率（peak negative mechanical power）最大，为1.8 ± 0.5 W/kg，其次为膝关节（0.8 ± 0.3 W/kg）与踝关节（0.2 ± 0.1 W/kg）。单次站坐转换动作中，髋关节、膝关节与踝关节的负机械功（negative mechanical work）分别为0.35 ± 0.06 J/kg、0.15 ± 0.08 J/kg及0.02 ± 0.01 J/kg。
假设再生驱动器的效率为已知值（最高可达63%），则机器人外骨骼与义肢在坐下过程中理论上可回收约26焦耳的电能，而单次行走步幅（walking stride）仅可回收约19焦耳电能。鉴于本研究的回收性能计算基于健康年轻人群，未来研究应纳入老年人或康复患者群体，以更精准地估算运动障碍（mobility impairments）人群可用于能量回收的生物力学能量。
参考文献：Laschowski B, Razavian RS, 及 McPhee J. (2020). 《面向能量回收型下肢外骨骼与义肢设计的站坐生物力学仿真》. bioRxiv. DOI: 10.1101/801258.