# Effect of hip abduction assistance on metabolic cost and balance during human walking [https://doi.org/10.5061/dryad.8gtht76vq](https://doi.org/10.5061/dryad.8gtht76vq) J. Park, et.al. prepared by Juneil Park last updated: August, 2022 Data are provided as a .mat file with the following name: Hip\_ABD.mat This MATLAB file provides the time series of data from tethered system, balance-related parameters, spatio-temporal parameters and metabolic cost for each participant and condition. To access the data, type the following into the MATLAB command line: load Hip\_ABD.mat Loading this .mat file will give access to the following data: 1. .sub# , # 1, 2, ... 7. Substructure for data of Subject X 2. .NW / .MFMP / .PFMP / .MSMP / .PSMP : Substructure for data of each profile 2-1) .characteristic: .characteristic contained information about height, body mass and age of each participant. 3-1) ctl\_param power: mechanical power delivered by exosuit (W/kg) ref\_force\_R: reference force on right leg (N) force\_R : actual force on right leg (N) ref\_force\_L: reference force on left leg (N) force\_L: actual force on left leg (N) angvel\_t: angular velocity of thigh IMU (rad/s) angvel\_r: angular velocity of right foot IMU (rad/s) angvel\_l: angular velocity of left foot IMU (rad/s) ref\_cur\_r: reference current of right motor (%norm current) act\_cur\_r: actual current of right motor (%norm current) ref\_cur\_r: reference current of left motor (%norm current) act\_cur\_r: actual current of left motor (%norm current) 3-2) br\_param mos: Margin of stability in medio-lateral direction (m) xcom: Extrapolated center of mass in medio-lateral direction (m) bos: Base of support in medio-lateral direction (m) stepwidth: average and variability of stepwidth CoP\_variability: variability of center of pressure (%norm current) 3-3) st\_param stridelength: stride length (m) cadence : cadence (s^-1) stancetime: time for stance phase (s) double\_stancetime: duration of double stance phase normalized by gait cycle (% gcp) swingtime: time for swing phase (s) 3-4) kinemaic\_CoM pos: position of the center of mass in mediolateral direction (m) vel: velocity of the center of mass in mediolateral direction (m^s-1) acc: acceleration of the center of mass in mediolateral direction (m^s-2) 3-4) metdata Net metabolic cost of each condition (W/kg) In each condition the following fields are available: (...). raw - contains stride-by-stride data of the last 120 strides (last 2mins used for EMG) [Note, raw data is not available in the dataset; please email corresponding author for the full set] (...). avg - the average of the .raw field (...). std - the standard deviation of the .raw field

The use of wearable robots to provide walking assistance has rapidly grown over the last decade, with significant advances made in robot design and control methods toward reducing physical effort while performing an activity. The reduction in the walking effort has mainly been achieved by assisting forward progression in the sagittal plane. Human gait, however, is a complex movement that combines motions in three planes, not only the sagittal but also the transverse and frontal planes. In the frontal plane, the hip joint plays a key role in gait, including balance. However, wearable robots targeting this motion have rarely been investigated. In this study, we developed a hip abduction assistance wearable robot by formulating the hypothesis that assistance that mimics the biological hip abduction moment or power could reduce the metabolic cost of walking and affect the dynamic balance. We found that hip abduction assistance with a biological moment second peak mimic profile reduced the metabolic cost of walking by 11.6% compared to the normal walking condition (p=0.009). The assistance also influenced balance-related parameters, including the margin of stability. Hip abduction assistance influenced the center-of-mass movement in the mediolateral direction. When the robot assistance was applied as the center of mass moved toward the opposite leg, the assistance replaced some of the efforts that would have otherwise been provided by a human. This indicates that hip abduction assistance can reduce physical effort during human walking while influencing balance.