Stair Navigation Research Articles

Step Test Evaluation of Performance on Stairs (STEPS): Assessing Stair Function in Older Adults.

Stair negotiation is crucial for functional independence and is a leading cause of fall-related injuries in older adults. The Step Test Evaluation of Performance on Stairs (STEPS) is a quick and easily administered outcome measure for assessing stair negotiation. This study investigated the reliability and concurrent content validity of the STEPS test to determine its usefulness in older adults. Eighty-two community-dwelling older adults (mean age 81.2years, 51 females) were assessed on the STEPS test, Timed Up and Go (TUG), 5-times sit to stand (5XSTS), stair self-efficacy (SSE) questionnaire, and time to ascend and descend stairs. Participants repeated the STEPS test 7 to 14days later for intrarater reliability by the same rater. Spearman rank and intraclass correlations were used to determine the association of measures and intrarater reliability. The mean STEPS score was 15.6 (SD=3.7) out of 20. The STEPS total score demonstrated excellent intra- and interrater reliability. It had moderate to good and significant correlations with TUG, 5XSTS, SSE, and time to ascend and descend measures. Faster performance on the 5XSTS, TUG, and time to ascend and descend correlated with better performance on the STEPS test, indicating validity for assessing balance and mobility during stair negotiation in older adults. Lower SSE correlated with lower observer ratings of performance on stairs (STEPS scores), indicating agreement between participant reports of self-efficacy and observer ratings of performance. Step Test Evaluation of Performance on Stairs items that demonstrated the most frequent loss of points were balance (use of handrail), step continuity, foot placement, and self-propulsion (ascent only). Assessment of older adults' safety and performance on stairs is vital given the increased difficulty of stair navigation and the high risk for injurious falls in this population. This study demonstrates that the STEPS test is a reliable and valid outcome measure for assessing stair performance in older adults.

Activity-Dependent Compensation at the Hip and Ankle at 8 Years After the Reconstruction of Isolated and Combined Posterior Cruciate Ligament Injuries

Background: After posterior cruciate ligament reconstruction (PCLR), functional deficits at the knee can persist. It remains unclear if neighboring joints compensate for the knee during demanding activities of daily living. Purpose: To assess long-term alterations in lower limb mechanics in patients after PCLR. Study Design: Descriptive laboratory study. Methods: A total of 28 patients who had undergone single-bundle unilateral isolated or combined PCLR performed stair navigation, squat, sit-to-stand, and stand-to-sit tasks at 8.2 ± 2.2 years after surgery. Motion capture and force plates were used to collect kinematic and kinetic data. Then, 3-dimensional hip, knee, and ankle kinematic data of the reconstructed limb were compared with those of the contralateral limb using statistical parametric mapping. Results: Side-to-side differences at the knee were primarily found during upward-driven movements at 8 years after surgery. The reconstructed knee exhibited lower internal rotation during the initial loading phase of stair ascent versus the contralateral knee (P = .005). During the sit-to-stand task, higher flexion angles during the midcycle (P = .017) and lower external rotation angles (P = .049) were found in the reconstructed knee; sagittal knee (P = .001) and hip (P = .016) moments were lower in the reconstructed limb than the contralateral limb. In downward-driven movements, side-to-side differences were minimal at the knee but prominent at the ankle and hip: during stair descent, the reconstructed ankle exhibited lower dorsiflexion and lower external rotation during the midcycle versus the contralateral ankle (P = .006 and P = .040, respectively). Frontal hip moments in the reconstructed limb were higher than those in the contralateral limb during the stand-to-sit task (P = .010); during squats, sagittal hip angles in the reconstructed limb were higher than those in the contralateral limb (P < .001). Conclusion: Patients after PCLR exhibited compensations at the hip and ankle during downward-driven movements, such as stair descent, squats, and stand-to-sit. Conversely, residual long-term side-to-side differences at the knee were detected during upward-driven movements such as stair ascent and sit-to-stand. Clinical Relevance: After PCLR, side-to-side differences in biomechanical function were activity-dependent and occurred either at the knee or neighboring joints. When referring to the contralateral limb to assess knee function in the reconstructed limb, concentric, upward-driven movements should be prioritized. Compensations at the hip and ankle during downward-driven movements lead to biases in long-term functional assessments.

Ankle and Foot Health Status in Primary School Teachers (Cross-Sectional Study)

Background: Prolonged standing and the demands of teaching significantly impact the foot health of primary school teachers. Previous studies have highlighted the prevalence of foot problems in this demographic, but there is a lack of comprehensive research specifically targeting the relationship between occupational demands and foot health among teachers. Objective: This study aims to assess the foot and ankle health of primary school teachers, examining the impact of prolonged standing and other occupational factors on their foot health and overall quality of life. Methods: A cross-sectional study was conducted over a six-month period, involving 400 primary school teachers aged 23-40 years, selected through non-probability purposive sampling. Participants with a history of foot trauma or surgery were excluded. The Foot and Ankle Disability Index (FADI) was utilized for data collection, assessing functional disability related to the foot and ankle. Data analysis employed descriptive and inferential statistics, including Pearson Correlation tests, using SPSS software version 25. Results: The study found that 60% of teachers reported foot discomfort, with 30% experiencing moderate to severe pain. Difficulty in stair navigation was evident, with 25.9% experiencing difficulty in going up stairs and 26.8% in going down stairs. A strong correlation was observed between the total FADIS score and general level of pain (Pearson Correlation .713). Severe foot pain corresponded with lower FADI scores, indicating a negative impact on daily functioning and quality of life. Conclusion: The study concludes that primary school teachers face significant foot health challenges, likely due to the occupational demands of prolonged standing and inadequate footwear. The findings suggest the need for ergonomic workplace adjustments and awareness programs to mitigate these issues. Interventions focusing on appropriate footwear and regular breaks could enhance foot health and overall well-being.

Invited Session IV: Extended reality--applications in vision science and beyond: Augmented reality systems for people with low vision.

Low vision is a visual impairment that falls short of blindness but cannot be corrected by eyeglasses or contact lenses. While current low vision aids (e.g., magnifier, CCTV) support basic vision enhancements, such as magnification and contrast enhancement, these enhancements often arbitrarily alter a user's full field of view without considering the user's context, such as their visual abilities, tasks, and environmental factors. As a result, these low vision aids are not sufficient or preferred by low vision users in many important tasks. Augmented reality (AR) technology presents a unique opportunity to enhance low vision people's visual experience by automatically recognizing the surrounding environment and presenting tailored visual augmentations. In this talk, I will talk about how we design and build intelligent AR systems to support low vision people in visual tasks, such as a head-mounted AR system that presents visual cues to orient users' attention in a visual search task, as well as a projection-based AR system that projects visual highlights on the stair edges to support safe stair navigation. I will conclude my talk by discussing our future research direction on AR for low vision accessibility.

Biomechanical effects of an articulating prosthetic toe joint during stair navigation for individuals with unilateral, below-knee limb loss

Stair navigation is an essential and demanding form of locomotion. During stair ascent and descent, persons with lower limb loss exhibit gait characteristics which may increase their risk of falls and joint degeneration of the intact limb. To reduce deviations from typically-able-bodied gait and overloading of the intact limb for this population, one potential intervention involves modifying passive prosthetic feet by incorporating a flexible toe joint that simulates the biological metatarsophalangeal joint. In this study, we aimed to assess the user preferences and biomechanical effects of a flexible prosthetic toe joint during stair ascent and descent for persons with unilateral lower-limb loss. Nine participants with unilateral lower-limb loss were recruited (Male; Medicare Functional Classification Level: eight K4, one K3; age: 41 ± 11 years; mass: 95 ± 13 kg; height: 1.84 ± 0.05 m; mean ± SD). No significant changes in lower-limb joint mechanics were identified. Five of nine participants preferred the unmodified prosthesis with a standard carbon fiber keel for both stair ascent and descent. Varied user preferences and inconsistent changes in lower-limb joint parameters between participants highlight the importance of subject-specific analyses and individualized device prescription.

Gait parameters, functional performance and physical activity in active and inactive Juvenile Idiopathic Arthritis

BackgroundChildren with Juvenile Idiopathic Arthritis (JIA) may adopt different movement patterns and participate in physical activity during different states of disease. Research questionWhich specific features of gait and physical function performance differ among children with active or inactive JIA compared to healthy children? MethodsForty-three children participated (14.5 ± 4.2 yrs; 60 % female). 3D-motion analysis methods were coupled with force measures from an instrumented treadmill captured gait mechanical measures. The 30-second Chair Rise Test (repetitions) and stair ascent-descent tests were performed, and the 11-point Wong-Baker face scale assessed pain after each test. ResultsCompared to healthy controls children with active and inactive JIA had worse outcomes (12–21 % slower self-selected and fast walking speeds, 28–34 % slower stair navigation times, 28 % fewer chair rise repetitions in 30 s; all p < .05). Children with active JIA had 8–13 % slower gait speeds, 4 % fewer chair rise repetitions and 14–16 % slower stair navigation times. At faster walking speed, children with active JIA had less hip joint flexion/extension excursion in the sagittal plane during the gait cycle, produced higher leg stiffness, and demonstrated greater interlimb asymmetry in GRF vertical impulse during loading than healthy children (all p < .05). The Pedi-FABS subscore of “Duration: performing athletic activity for as long as you would like without stopping” was rated lower in children with active JIA compared to controls (p < .05). ConclusionGait speed, specific load-bearing functional tasks and leg stiffness features of gait may be informative ‘functional biomarkers’ for assessing JIA burden and tracking treatment efficacy. Additional prospective studies are needed to determine how these features change over time with pain change, and understand impact on quality of life and physical activity participation.

The relationships of kinesiophobia and physical function and physical activity level in juvenile idiopathic arthritis

BackgroundKinesiophobia may hinder physical performance measures and functional quality of life in children with juvenile idiopathic arthritis (JIA). This study aims to quantify differences in physical function in patients with JIA compared to healthy controls, and determine the effects of kinesiophobia on physical function and physical activity.MethodsThis was a comparative study of participants with JIA and healthy controls (JIA n = 26, control n = 17). All children with JIA had lower extremity joint involvement. Performance-based measures included gait speed, chair and stair navigation performance. Self-reported measures included Patient Reported Outcome Measurement Information System (PROMIS®) Physical Function Mobility, and Pain Interference and the Pediatric Functional Activity Brief Scale (Pedi-FABS). The Tampa Scale of Kinesiophobia (TSK-11) assessed patient fear of movement due to pain. Linear regression models were used to determine the contribution of TSK-11 scores on performance test and Pedi-FABS scores.ResultsGait speeds were 11–15% slower, chair rise repetitions were 28% fewer, and stair ascent and descent times were 26–31% slower in JIA than controls (p < .05). PROMIS® Physical Function Mobility scores were 10% lower and Pain Interference scores were 2.6 times higher in JIA than healthy controls (p = .003). TSK-11 scores were higher in JIA than controls (p < .0001). After controlling for covariates, TSK-11 scores explained 11.7–26.5% of the variance of regression models for stair climb time, chair rise performance and Pedi-FABS scores (p < .05).ConclusionsChildren with JIA experience difficulty with tasks related to body transfers. Kinesiophobia is a significant contributor to the functional task performance and may impact clinical outcomes.

Association Between Knee Moments During Stair Navigation and Participant-Related Factors in Individuals With Anterior Cruciate Ligament Reconstruction: A Cross-Sectional Study.

Altered knee joint mechanics may be related to quadriceps muscle strength, time since surgery, and sex following anterior cruciate ligament reconstruction (ACLR). The aim of this study was to investigate the association between knee moments, with participant-related factors during stair navigation post-ACLR. Cross-sectional study. A total of 30 participants (14 women) with ACLR, on average 7.0 (SD 4.4) years postsurgery were tested during stair ascent and descent in a gait laboratory. Motion capture was conducted using a floor-embedded force plate and 11 infrared cameras. Quadriceps concentric and eccentric muscle strength was measured with an isokinetic dynamometer at 60°/s, and peak torques recorded. Multiple regression analyses were performed between external knee flexion and adduction moments, respectively, and quadriceps peak torque, sex, and time since ACLR. Higher concentric quadriceps strength and female sex accounted for 55.7% of the total variance for peak knee flexion moment during stair ascent (P < .001). None of the independent variables accounted for variance in knee adduction moment (P = .698). No significant associations were found for knee flexion and adduction moments during for stair descent. Higher quadriceps concentric strength and sex explains major variance in knee flexion moments during stair ascent. The strong association between muscle strength and external knee flexion moments during stair ascent indicate rehabilitation tailored for quadriceps may optimize knee mechanics, particularly for women.

Biomechanics of Single Stair Climb With Implications for Inverted Pendulum Modeling.

Step-by-step (SBS) stair navigation is used by those with movement limitations or lower-limb prosthetics and by humanoid robots. Knowledge of biomechanical parameters for SBS gait, however, is limited. Inverted pendulum (IP) models used to assess dynamic stability have not been applied to SBS gait. This study examined the ability of the linear inverted pendulum (LIP) model and a closed-form, variable-height inverted pendulum (VHIP) model to predict capture-point (CP) stability in healthy adults executing a single stair climb. A second goal was to provide baseline kinematic and kinetic data for SBS gait. Twenty young adults executed a single step onto stairs of two heights, while attached marker positions and ground reaction forces were recorded. opensim software determined body kinematics and joint kinetics. Trials were analyzed with LIP and VHIP models, and the predicted CP compared to the actual center-of-pressure (CoP) on the stair. Lower-limb joint moments were larger than those reported for step-over-step (SOS) stair gait. Leading knee rather than trailing ankle was dominant. Center-of-mass (CoM) velocity peaked at push-off. The VHIP model accounted for only slightly more than half of the forward progression of the vertical projection of the CoM and was not better than LIP predictions. This suggests that IP models are limited in modeling SBS gait, likely due to large hip and knee moments. The results from this study may also provide target values and strategies to aid design of lower-limb prostheses and powered exoskeletons.

Intermittent vibrational stimulation enhances mobility during stair navigation in patients with knee pain

BackgroundReduced quadriceps function and proprioception can cause decreased mobility during stair navigation in patients with knee pain. Patients can benefit from interventions to mitigate pain and restore quadriceps function. Activating the somatosensory system via intermittent vibrational stimulation has the potential to improve stair navigation mobility in patients with knee pain by moderating quadriceps inhibition and enhancing proprioception. Research questionWhat are the effects of intermittent vibrational stimulus synchronized to stair ambulation on muscle activity, kinematics, kinetics, and pain using a randomized controlled clinical trial design. MethodsThirty-eight patients with knee pain were enrolled into a blinded cross-over study, and twenty-nine patients completed all assessments and analyses. Subjects were randomly assigned sequentially to both an active Treatment A (active) and passive Treatment B (passive) worn at the knee during ambulation for 4 weeks with a 2-week washout period between treatments. ResultsKnee pain during stair navigation was significantly reduced only with Treatment A (P = 0.007). During ascent, Treatment A (active) significantly increased vastus lateralis activation (P = 0.01), increased knee flexion moment (P = 0.04) and decreased trunk flexion angles (P = 0.015) between baseline and 4-week follow-up. After using passive Treatment B, there were no significant differences in pain (P = 0.19), knee flexion moment (P = 0.09), and trunk flexion angles (P = 0.23). Changes in muscle function correlated significantly with changes in knee flexion moment and trunk flexion with Treatment A (P < 0.015).Descending differed from ascending in response to Treatment A with significantly decreased knee flexion moment(P = 0.04), hip(P = 0.02) and ankle(P = 0.04) flexion angles. Treatment B significantly reduced hip flexion angles (P = 0.005) but not knee flexion moment (P = 0.85). SignificanceThe results of this study suggest that intermittent vibration can improve joint motion and loading during stair navigation by enhancing quadriceps function during stair ascent and improving movement control during stair descent by modifying an adaptive flexed movement pattern in the lower limb.

Implant design affects walking and stair navigation after total knee arthroplasty: a double-blinded randomised controlled trial

BackgroundDissimilar total knee arthroplasty implant designs offer different functional characteristics. This is the first work in the literature to fully assess the Columbus ultra-congruent mobile (UCR) system with a rotating platform.MethodsThis is a double-blinded randomised controlled trial, comparing the functional performance of the low congruent fixed (CR DD), ultra-congruent fixed (UC) and UCR Columbus Total Knee Systems. The pre-operative and post-operative functional performance of twenty-four osteoarthritic patients was evaluated against nine control participants when carrying out everyday tasks. Spatiotemporal, kinematic and kinetic gait parameters in walking and stair navigation were extracted by means of motion capture.ResultsThe UC implant provided better post-operative function, closely followed by the UCR design. However, both the UC and UCR groups exhibited restricted post-operative sagittal RoM (walking, 52.1 ± 4.4° and 53.2 ± 6.6°, respectively), whilst patients receiving a UCR implant did not show an improvement in their tibiofemoral axial rotation despite the bearing’s mobile design (walking, CR DD 13.2 ± 4.6°, UC 15.3 ± 6.7°, UCR 13.5 ± 5.4°). Patients with a CR DD fixed bearing showed a statistically significant post-operative improvement in their sagittal RoM when walking (56.8 ± 4.6°).ConclusionIt was concluded that both ultra-congruent designs in this study, the UC and UCR bearings, showed comparable functional performance and improvement after TKA surgery. The CR DD group showed the most prominent improvement in the sagittal RoM during walking.Trial registrationThe study is registered under the clinical trial registration number: NCT02422251. Registered on April 21, 2015.

The Intersecting Influence of Age and Performance Stereotypes on Physical and Psychological Aspects of Stair Navigation in Older Adults.

Negative age-stereotypes can have widespread effects on older adult functionality; however, no research has explored psychophysical aspects of stair navigation after exposure to stereotype priming. The present study examined self-efficacy and biomechanics related to stair navigation in older adults (N = 90). Between-groups analyses revealed positively primed older adults ascended and descended the stairs significantly faster with greater velocity in the medio-lateral plane than older adults who received a negative prime or controls (p < .017). Moreover, negatively primed older adults rated their stair self-efficacy significantly lower compared with the control and positively primed groups (p < .017). These results suggest positively primed older adults can navigate stairs with more confidence, quickness, and efficiency. With implications for interventions aimed at maintaining older adult functionality, the present study highlights the potential benefits of positive age-stereotypes, especially related to challenging physical tasks.

Use of Virtual Reality Simulation to Identify Vision-Related Disability in Patients With Glaucoma

Clinical assessment of vision-related disability is hampered by the lack of instruments to assess visual performance in real-world situations. Interactive virtual reality (VR) environments displayed in a binocular stereoscopic VR headset have been designed, presumably simulating day-to-day activities to evaluate vision-related disability. To investigate the application of VR to identify vision-related disability in patients with glaucoma. In a cross-sectional study, 98 patients with glaucoma and 50 healthy individuals were consecutively recruited from a university eye clinic; all participants were Chinese. The study was conducted between August 30, 2016, and July 31, 2017; data analysis was performed from December 1, 2017, to October 30, 2018. Measurements of visual acuity, contrast sensitivity, visual field (VF), National Eye Institute 25-item Visual Function Questionnaire Rasch score, and VR disability scores determined from 5 VR simulations: supermarket shopping, stair and city navigations in daytime, and stair and city navigations in nighttime. Duration required to complete the simulation, number of items incorrectly identified, and number of collisions were measured to compute task-specific and overall VR disability scores. Vision-related disability was identified when the VR disability score was outside the normal age-adjusted 95% confidence region. Virtual reality disability score. In the 98 patients with glaucoma, mean (SD) age was 49.8 (11.6) years and 60 were men (61.2%); in the 50 healthy individuals, mean (SD) age was 48.3 (14.8) years and 16 were men (32.0%). The patients with glaucoma had different degrees of VF loss (122 eyes [62.2%] had moderate or advanced VF defects). The time required to complete the activities by patients with glaucoma vs healthy individuals was longer by 15.2 seconds (95% CI, 5.5-24.9 seconds) or 34.1% (95% CI, 12.4%-55.7%) for the shopping simulation, 72.8 seconds (95% CI, 23.0-122.6 seconds) or 33.8% (95% CI, 10.7%-56.9%) for the nighttime stair navigation, and 38.1 seconds (95% CI, 10.9-65.2 seconds) or 30.8% (95% CI, 8.8%-52.8%) for the nighttime city navigation. The mean (SD) duration was not significantly different between the glaucoma and healthy groups in daytime stair (203.7 [93.7] vs 192.9 [89.1] seconds, P = .52) and city (118.7 [41.5] vs 117.0 [52.3] seconds, P = .85) navigation. For each decibel decrease in binocular VF sensitivity, the risk of collision increased by 15% in nighttime stair (hazard ratio [HR], 1.15; 95% CI, 1.08-1.22) and city (HR, 1.15; 95% CI, 1.08-1.23) navigations. Fifty-eight patients (59.1%) with glaucoma had vision-related disability in at least 1 simulated daily task; a higher proportion of patients had vision-related disability in nighttime city (27 of 88 [30.7%]) and stair (27 of 90 [30.0%]) navigation than in daytime city (7 of 88 [8.0%]) and stair (19 of 96 [19.8%]) navigation. The overall VR disability score was associated with the National Eye Institute 25-item Visual Function Questionnaire Rasch score (R2 = 0.207). These findings suggest that vision-related disability is associated with lighting condition and task in patients with glaucoma. Virtual reality may allow eye care professionals to understand the patients' perspectives on how visual impairment imparts disability in daily living and provide a new paradigm to augment the assessment of vision-related disability.

Joint loading asymmetry is associated with the asymmetry in muscle strength in people with anterior cruciate ligament reconstruction

Introduction: Participants with anterior cruciate ligament (ACL) injury are at a high risk of both re-injury and osteoarthritis. Altered joint loading between the injured leg and the contralateral limb has been reported to persist following anterior cruciate ligament reconstruction (ACLR) surgery and may be related, positively or negatively, to asymmetrical quadriceps muscle strength, time since ACLR, and participant's sex post-surgery. The aim of this study was to investigate the association between limb loading (peak knee flexion and adduction moments) asymmetry, and participant-related factors during stair navigation post-ACLR.

Foot clearance and variability in mono- and multifocal intraocular lens users during stair navigation.

Intraocular lenses (IOLs) provide distance and near refraction and are becoming the standard for cataract surgery. Multifocal glasses increase variability of toe clearance in older adults navigating stairs and increase fall risk; however, little is known about the biomechanics of stair navigation in individuals with multifocal IOLs. This study compared clearance while ascending and descending stairs in individuals with monofocal versus multifocal IOLs. Eight participants with multifocal IOLs (4 men, 4 women; mean age = 66.5 yr, standard deviation [SD] = 6.26) and fifteen male participants with monofocal IOLs (mean age = 69.9 yr, SD = 6.9) underwent vision and mobility testing. Motion analysis recorded kinematic and custom software-calculated clearances in three-dimensional space. No significant differences were found between groups on minimum clearance or variability. Clearance differed for ascending versus descending stairs: the first step onto the stair had the greatest toe clearance during ascent, whereas the final step to the floor had the greatest heel clearance during descent. This preliminary study indicates that multifocal IOLs have similar biomechanic characteristics to monofocal IOLs. Given that step characteristics are related to fall risk, we can tentatively speculate that multifocal IOLs may carry no additional fall risk.

Towards Dynamics and Control of an Arm-Wheel Based Autonomous Stair Climbing Robotic Vehicle

The paper describes the dynamics and control aspects of an arm wheel based mobile robot for stair navigation with such features as skid steered motion on flat surface, navigation on staircase i.e. ascending and descending stairs keeping payload carrier platform parallel to the ground. A feedback linearization control scheme is adopted to decipher the skid steer phenomena. The nearness of the experimental data to corresponding simulated data validates design and analysis of the present system.

Medial Longitudinal Arch Deformation during Walking and Stair Navigation While Carrying Loads

Understanding the biomechanics of the medial longitudinal arch (MLA) may provide insights into injury risk and prevention, as well as function of the arch-supporting structures. Our understanding of MLA deformation is currently limited to sit-to-stand, walking, and running. Three-dimensional deformation of the MLA of the right foot was characterized in 17 healthy participants during several simulated activities of daily living. MLA deformation was quantified by both changes in arch length and navicular displacement during the stance phase of three motions: walking, stair ascent, and stair descent. Three levels of load were also evaluated: no load, a front load (13.6 kg), and a backpack load (13.6 kg). Force platforms and an eight-camera motion capture system were used to collect relevant lower extremity kinetic and kinematic data. Motion type had a significant (p < 0.05) effect on navicular displacement and arch length elongation with navicular displacement being greatest during stair descent, while the walking and stair descent conditions showed the greatest increase in arch length. External load did not significantly affect either of these two measures (p > 0.05). Differences in the MLA deformation variables resulting from varied dynamic activities of daily living can be greater than those during walking and should be considered. Detailing the mechanics of the MLA may aid in further understanding injuries associated with the MLA, and the results of the current study indicate that these mechanics change based on activity.

Design and fabrication of a statically stable stair‐climbing robotic wheelchair

PurposeThe purpose of this paper is to present the mechanical design and stability analysis of a new stair‐climbing robotic wheelchair.Design/methodology/approachA prototype stair‐climbing robotic wheelchair is constructed comprising a pair of rotational multi‐limbed structures pivotally mounted on opposite sides of a support base. The short arm, long arm, and triangular support structures within each rotational multi‐limbed structure rotate under the actuating effects of epicyclical gear trains.FindingsThe robotic wheelchair ascends and descends stairs in a statically stable manner and has an efficient planar navigation capability.Research limitations/implicationsIn its current state of development, the robotic wheelchair is controlled and powered remotely via umbilical cords rather than an onboard processor and power supply.Practical implicationsThe robotic wheelchair provides an effective solution for enhancing the mobility of the elderly and disabled.Originality/valueThe rotational multi‐limbed mechanisms are developed to ensure the stability of the sitting base at all stages of the stair navigation maneuver without the need for additional servo‐mechanism. The proposed robotic wheelchair shows the simplification of the associated operation process.

How do the elderly negotiate stairs?

Stair navigation, particularly stair descent, is an extremely challenging and dangerous locomotor task, yet studies suggest that most elderly are unlikely to move to new residences in order to avoid this challenge. The knee and ankle are the key joints where adequate strength and power are required for safe stair descent, and it is not yet clear if sarcopenia in the elderly is likely to result in residual strength below that which is required for successful stair performance. Sensory cues are also critical, and the lack of literature on the specific roles of the various intrinsic and extrinsic factors that affect stair navigation is a clear indication of the need for such research in order to define safer strategies and optimal conditions for elderly individuals to transit between living areas of differing levels.

Robot Design for Stair Navigation

Among the several designs of mobile robots, the wheel design is unfavorable for navigation of stairs or over obstacles. The leg design and the creeping design demand very intricate control systems and are not efficient on flat surfaces. The caterpillar design is unreliable and unstable in stair navigation. In the arm-wheel design, the sensor which discriminates between stairs and flat surfaces and the mechanism which alternates between wheel-running and arm-creeping modes are complicated. In this paper, a new type of arm-wheel design for a mobile robot enabling it to navigate stairs is developed, which requires no sensor for discrimination between stairs and flat surfaces of stairs and no mechanism for alternating between wheel-running and arm-creeping modes. Since no sensor is required, the reliability in an extreme environment is high. Moreover, since it has no intricate discrimination mechanism, it can also be applied to a wheelchair, for example, which is not powered. The author has confirmed through experiments using a stair-navigating robot prototype that the mechanism developed here functions as intended.