Evaluation of the power deficit of elderly people during stair negotiation: Which joints should be assisted at least by an exoskeleton and with what amount?

Abstract

Climbing stairs can become a daily obstacle for elderly people, and an exoskeleton can assist here. However, the exoskeletons that are designed to assist stair climbing are actuated in different ways. To find a minimal actuation configuration, we identify the assist phases by evaluating the power deficit of 11 healthy but weak elderly people (72.4 ± 2.1 years; 69–76 years; 1.67 ± 0.10 m; 74.88 ± 14.54 kg) compared to 13 younger people (24.0 ± 1.8 years; 22–28 years; 1.74 ± 0.10 m; 70.85 ± 11.91 kg) in a biomechanical study and discuss moment characteristics. Three-dimensional kinematics and ground reaction forces were collected, and kinematics, kinetics, and power characteristics of each subject for ascent and descent were calculated using inverse dynamics. Significant differences for power between both groups were assessed with statistical parametric mapping method using dynamic time warping. During ascent, the largest significant power deficit of the elderly subjects occurs in the single stance phase (SSP) during pull-up in the knee joint. During descent, significant mean power deficits of 0.2 and 0.8 W/kg for the highest deficit occur in the ankle joint in the beginning of the SSP and also in the knee joint in the same phase. Therefore, an exoskeleton should address the power deficit for knee extension (ascent: 1.0 ± 0.9 W/kg; descent: 0.3 ± 0.2 W/kg) and could assist the ankle during ascent and descent by an additional plantar flexion moment of 0.2 Nm/kg each.

Ergonomic dual four-bar linkage knee exoskeleton for stair ascent assistance

“…The reported peak torque normalized to body mass varies from as low as 0.58 Nm·kg −1 in Protopapadaki et al (2007) to as high as 1.72 Nm·kg −1 in Larsen et al (2009) . The angle at which the peak torque occurred also varies between 40° and 70° ( Andriacchi et al, 1980 ; McFadyen and Winter, 1988 ; Salsich et al, 2001 ; Riener et al, 2002 ; Hortobágyi et al, 2003 ; Reid et al, 2007 ; Reeves et al, 2009 ; Böhme et al, 2022 ). The maximum reported mean of peak flexion angle was 106° ( Böhme et al, 2022 ).…”

“…The angle at which the peak torque occurred also varies between 40° and 70° ( Andriacchi et al, 1980 ; McFadyen and Winter, 1988 ; Salsich et al, 2001 ; Riener et al, 2002 ; Hortobágyi et al, 2003 ; Reid et al, 2007 ; Reeves et al, 2009 ; Böhme et al, 2022 ). The maximum reported mean of peak flexion angle was 106° ( Böhme et al, 2022 ).…”

“…One significant factor contributing to this variation is the age of participants involved in the studies. For instance, Hortobágyi et al (2003) and Böhme et al (2022) specifically examined the effects of participant demographics on stair ascent kinetics. The results revealed a significant difference in peak knee torque between old and young groups, highlighting the influence of participant characteristics on the observed kinetics.…”

“… Hortobágyi et al (2003) found that old adults perform stair ascents near their maximal capabilities. Another study by Böhme et al (2022) reported a significant power deficit in the elderly during stair ascent.…”

Preliminary Biomechanical Evaluation of a Novel Exoskeleton Robotic System to Assist Stair Climbing

“…In recent years, more and more exoskeletons have been developed and tested for a wide range of applications [2]. Thus, a number of systems were also developed to assist people, especially elderly people, exclusively during stair climbing [3,4]. For example, an active system has been developed by [5] that consists of five parts and weighs about 13.5 kg.…”