Measurement and Simulation of Human Sitting and Standing Movement Biomechanics
Previous studies of robotic leg prostheses and exoskeletons with regenerative actuators have focused almost exclusively on level-ground walking applications. Here we analyzed the lower-limb joint mechanical work and power during stand-to-sit movements using inverse dynamics to estimate the biomechanical energy theoretically available for electrical energy regeneration and storage. Nine subjects performed 20 sitting and standing movements while lower-limb kinematics and ground reaction forces were experimentally measured. Subject-specific body segment inertial parameters were estimated using system parameter identification. Joint mechanical power was calculated from the net joint torques and angular velocities and numerically integrated over time to estimate the joint mechanical energy. The hip absorbed 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 on the hip, knee, and ankle joints 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 efficiency of ~63%), robotic leg prostheses and exoskeletons could theoretically regenerate ~26 J of electrical energy while sitting down, compared to ~19 J per level-ground walking stride. Given that these energy regeneration performance calculations are based on healthy young adults, future research should include older adults and/or persons with physical disabilities to better estimate the biomechanical energy available for electrical regeneration.
Reference: Laschowski B, Razavian RS, and McPhee J. (2021). Simulation of Stand-to-Sit Biomechanics for Robotic Exoskeletons and Prostheses with Energy Regeneration. IEEE Transactions on Medical Robotics and Bionics, 3(2), pp. 455-462. DOI: 10.1109/TMRB.2021.3058323.
*Details on the biomechanics dataset are provided in the reference above. Please email Brokoslaw Laschowski (email@example.com) for any additional questions and/or technical assistance.