Stair-climbing wheelchair proven to maintain user’s body stability based on AnyBody musculoskeletal model and finite element analysis

PLOS ONE RESEARCH ARTICLE Stair-climbing wheelchair proven to maintain user’s body stability based on AnyBody musculoskeletal model and finite element analysis Yancong Zhu1☯, Haojie Li ID2☯, Shaojun Lyu2*, Xinying Shan ID1,3*, Yih-Kuen Jan ID4, Fengling Ma3 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Zhu Y, Li H, Lyu S, Shan X, Jan Y-K, Ma F (2023) Stair-climbing wheelchair proven to maintain user’s body stability based on AnyBody musculoskeletal model and finite element analysis. PLoS ONE 18(1): e0279478. https://doi.org/ 10.1371/journal.pone.0279478 Editor: Gustavo Plaza-Manzano, Complutense University of Madrid: Universidad Complutense de Madrid, SPAIN Received: October 27, 2022 Accepted: December 7, 2022 Published: January 26, 2023 Copyright: © 2023 Zhu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 1 School of Biological Science and Medical Engineering, Beihang University, Beijing, China, 2 School of P.E and Sports, Beijing Normal University, Beijing, China, 3 Department of Rehabilitation Technical Aids for OldAge Disability, National Research Center for Rehabilitation Technical Aids, Beijing, China, 4 University of Illinois at Urbana-Champaign Champaign, Champaign, IL, United States of America ☯ These authors contributed equally to this work. * (SL); (XS) Abstract The electric stair-climbing wheelchair is a beneficial mobile assistance device for older adults and disabled persons with poor walking ability, as it reduces the daily walking and climbing burden. In this paper, 11 older adults were tested when using a stair-climbing wheelchair in three environments: flat ground, slopes, and stairs. The kinematic and dynamic parameters of the lower limb joints were simulated by AnyBody 7.2 human model simulation software using Vicon 3D infrared motion capture, a 3D force table, and analyzed by ANSYS 19.2 Workbench. The joint force, joint moment, and muscle strength did not change significantly under the three environments when using the wheelchair. Through finite element analysis of the mechanical properties of the human body, when using the wheelchair, no significant differences in the overall stress distributions of the fifth lumbar spine, hip bone, or femur were found among the three environments, no significant differences in deformation and displacement were found, and the stress distribution was relatively stable. Therefore, the human body is stable enough to use the electric stair-climbing wheelchair in the three test environments, all of which will be commonly encountered in daily life. Data Availability Statement: All datasets are publicly available at: https://doi.org/10.6084/m9. figshare.21701456.v2. Funding: This research was supported by the National Key R&D Program of China (2020YFC2005801) to Xinying Shan. Authorized Unit: National Research Center for Rehabilitation Technical Aids. URLs to sponsors’ websites: https://chinainnovationfunding.eu/national-key-rdprogrammes/. The funders had no role in study 1. Introduction The aging of the population is a global trend, and it is becoming a global challenge. In 2019, the 26th World Population Prospects Report of the United Nations noted that the world population is aging continuously. Older adults aged 65 and above accounted for one-tenth of the total population in 2019, and as the fastest-growing age group, are expected to account for one-sixth of the total population in 2050 [1]. According to the seventh census of China PLOS ONE | https://doi.org/10.1371/journal.pone.0279478 January 26, 2023 1 / 14 PLOS ONE design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: NO authors have competing interests. Stair-climbing wheelchair proven to maintain user’s body stability conducted in 2020, China’s population has exceeded 1.4 billion people, of which 264 million are over 60 years old, accounting for 18.7% of the total population; this is an increase of 5.44 percentage points compared with 2010. Some studies predict that the trend of population aging will continue in the next 10 years and peak in 2059, when there will be one older adult out of every three people [2]. Unfortunately, aging is accompanied by increased risk for many diseases and disabilities. Owing to a decline in physiological function or the influence of cardiovascular and cerebrovascular diseases, many older adults have difficulties standing and walking and face various challenges in their daily lives. For older adults, stair climbing is one of the most challenging and dangerous activities of daily life [3]. Jensen [4] noted that stair climbing is faced daily and is a critical aspect of community life. Many older adults and people with certain disabilities need to use crutches or wheelchairs for assistance with walking and climbing stairs. Wheelchairs are an essential mobility device for many older adults and physically disabled people. Electric wheelchairs have been widely used for many years. Today, it is quite common for an electric wheelchair to be a person’s primary mobility device to aid in daily activities, both indoors and outdoors [5]. However, it is still challenging for a standard electric wheelchair to overcome environmental barriers, such as stairs in buildings or civil infrastructure [6], especially for people living in buildings without elevators. Studies have shown that going uphill and climbing stairs are critical obstacles for wheelchair users, and it is difficult for older wheelchair users to overcome steps with a height of more than 20 cm [7]. Most electric wheelchairs require external assistance when traveling uphill and climbing stairs, so older adults may face risks when attempting to travel uphill independently. In addition, elevators cannot be used during disaster evacuations, such as for fires, earthquakes, and other disasters. Therefore, for the safety of wheelchair users, the ability to travel up and down stairs is a vital issue. To solve these problems, many designers have designed age-appropriate wheelchairs with usefulness and safety as the core principles [8]. For example, Erwin Prassler’s WHEELESLEY wheelchair adopts advanced human–computer interaction and environment perception technology, and it achieves intelligent obstacle avoidance [9]. Yi et al. successively designed intelligent wheelchairs based on surface electromyography (EMG), lip control, and wrist potential control [10–12]. However, these studies mainly focused on four aspects: motion control of the automatic platform, unique assistive technology, environmental awareness and navigation systems, and human–computer interaction technology [13]. Studies on the stability of stairclimbing wheelchairs are limited to the mechanical structural design and dynamic (...truncated)