Design of a multi-resiliency exoskeleton and its physiologic cost evaluation in uphill walking and stair climbing locomotion

Background In recent years, as the large own weight of active exoskeleton brings some difficulty to energy-sustainable, studies have shown that passive lower extremity exoskeletons can also reduce the energy consumption of human locomotion, but the energy saving is still relatively small compared with the total consumption. Methods A passive lower limb exoskeleton named Multi-Resiliency was described, and design parameters were estimated based on inverse dynamics. Furthermore, a series of experiments was designed for assessing the assisting effect of the exoskeleton in uphill walking and upstairs activities. Results In the inverse dynamics analysis, the spring release angle θmax was confirmed to be 45° for increasing assist performance of the exoskeleton. In the exoskeleton wearing experiments, the energy expenditure of subjects were decreased by 14.3% in uphill walking test and 16.0% in stair climbing test respectively. Conclusion The results show that the design of Multi-Resiliency exoskeleton is reasonable and it may effectively improve walking efficiency during uphill walking and stair climbing activities.

Outside testing of wearable robots for gait assistance shows a higher metabolic benefit than testing on treadmills

Most wearable robots that assist the gait of workers, soldiers, athletes, and hobbyists are developed towards a vision of outdoor, overground walking. However, so far, these devices have predominantly been tested indoors on laboratory treadmills. It is unclear whether treadmill-based laboratory tests are an accurate representation of overground ambulation outdoors with respect to essential outcomes such as the metabolic benefits of robotic assistance. In this study, we investigated the metabolic benefits of the Myosuit, a wearable robot that assists hip and knee extension during the stance phase of gait, for eight unimpaired participants during uphill walking trials in three settings: outside, on a self-paced treadmill with a virtual reality display, and on a standard treadmill at a fixed gait speed. The relative metabolic reduction with Myosuit assistance was most pronounced in the outside setting at − 10.6% and significantly larger than in the two treadmill settings (− 6.9%, p = 0.015 and − 6.2%, p = 0.008). This indicates that treadmill tests likely result in systematically low estimate for the true metabolic benefits of wearable robots during outside, overground walking. Hence, wearable robots should preferably be tested in an outdoor environment to obtain more representative—and ultimately more favorable—results with respect to the metabolic benefit of robotic gait assistance.

Are Medial and Lateral Tibiofemoral Compressive Forces Different in Uphill Compared to Level Walking for Patients Following Total Knee Arthroplasty?

The purpose of this study was to determine how tibiofemoral joint compressive forces and knee joint-spanning muscle forces during uphill walking change compared to level walking in patients with total knee arthroplasty (TKA). A musculoskeletal model capable of resolving total (TCF), medial (MCF), and lateral (LCF) tibiofemoral compressive forces was used to determine compressive forces and muscle forces during level and uphill walking on a 10° incline for twenty-five post TKA patients. A 2?2 (slope: level and 10° ? limb: replaced and non-replaced) repeated measures ANOVA was used to detect differences in knee contact forces between slope and limb conditions and their interaction. Peak loading-response TCF, MCF, and LCF were greater during uphill walking than level walking for non-replaced limbs. During uphill walking, peak loading-response TCF was smaller in the replaced limb compared to non-replaced limbs with no change in MCF or LCF. Peak knee extension moment and knee extensor muscle force were smaller in replaced limbs compared to non-replaced limbs during uphill walking. During level walking, replaced and non-replaced limbs experienced rather equal joint loading, however replaced limb experienced reduced joint loading during uphill walking. Differences in joint loading between replaced and non-replaced limbs were not present during level walking, suggesting compensation from the replaced limb during the more difficult task. Uphill walking following TKA promotes more balanced loading of replaced limbs during stance, however these benefits may come at the expense of increased loading on non-replaced limbs.

Effect of outdoor footwear bending stiffness on metatarsophalangeal joint kinematics, kinetics, and energy balance during level and uphill walking

In outdoor footwear, sole properties must guarantee grip with the ground and support the forefoot without altering the kinematics of the metatarsophalangeal joints (MPJ). The present study aimed to implement an objective measure of shoe bending stiffness and investigate the effect of shoes with different bending stiffness on MPJ kinematics, kinetics, and energy balance during walking. The bending stiffness of four shoes was calculated using a customized flexometer. Then, the influence of each footwear on MPJ biomechanics during level and uphill walking was investigated with a motion capture system and a force plate on 10 healthy subjects. Results showed that MPJ peak dorsiflexion angle, stiffness, and energy balance were affected both by shoe bending stiffness ( p<0.001) and walking slope ( p<0.001). The findings of the study, which quantify the influence of shoe stiffness on MPJ biomechanics, will be helpful in the design of outdoor footwear.

Effect of shod walking on plantar pressure with varying uphill gradients

Background: Uphill walking is biomechanically stressful. Changes in plantar pressure, is one of the important predictors of this stress and increased risk of foot injuries. It has been reported that civilians as well as different occupational workers have to walk over uphill gradient with footwear which may cause changes in plantar pressure. Till date published data on plantar pressure is not available of Indian population during shod walking with uphill gradients. Aims and Objective: The present study was aimed to generation of data base on plantar pressure and find out the effect of shod walking (wearing occupational boot) on plantar pressure at different uphill gradients. Materials and Methods: Twenty healthy male participated in this study. Plantar pressure was recorded using the pressure measurement system during walking at 4 km/hr speed on treadmill at level and different uphill gradients. Results: It was observed that the PP at all the five regions of both right and left foot (Forefoot, Mid-foot, Medial, Lateral, Heel and Overall) increased gradually along with the increase in gradients. There was significant increase of 8.94%, 9.93%, 18.22%, 16.06%, 10.27%, 12.92% respectively at left forefoot, mid-foot, heel, medial, lateral and overall regions at 10% gradient compared to level walking. Similarly, in right foot the increase was observed 8.20%, 10.82%, 14.28%, 13.75%, 8.27%, 10.88% in respective foot regions compared to level walking. Conclusion: Observations of the present study stated that with increasing gradient plantar pressure at various foot regions increased in both feet in comparison to level walking, maximum plantar pressure observed in heel region in both feet in comparison to other studied regions. This data will be considered as normal planter pressure value of adults at level and uphill gradients shod walking and may be utilized for prognosis of foot disorders and efficacy of treatment modalities of population comparable with studied individuals (for similar age, height and weight).