Step-Climbing Power Wheelchairs: A Literature Review

Design and analysis of a mobile robot with novel caster mechanism for high step-overcoming capability

The mobile robot market is experiencing rapid growth, playing a pivotal role in various human-centric environments like restaurants, offices, hotels, hospitals, apartments, and factories. However, current differential-driven mobile robots, employing conventional casters and wheel motors, encounter limitations in surmounting uneven surfaces and high steps due to constraints caused by wheel and caster dimensions. While some robots address these challenges by incorporating optimized wheel shapes and additional motors, this invariably leads to an increase in both size and cost. This research introduces an innovative solution; a novel caster-wheel mechanism designed to enhance the high-step overcoming capability of mobile robots without necessitating alterations to their overall size and structure. By incorporating a sub-wheel linked to a passive joint, the driving force is effeciently converted into a vertical force, thereby empowering the mobile robot to navigate obstacles 85% larger than its caster-wheel radius. Crucially, this innovative caster can be seamlessly manufactured and integrated, offering the potential for widespread adoption as a replacement for conventional casters. Validation through comprehensive simulations and experiments conducted on a prototype robot has been presented in this article, demonstrating its effectiveness even at a robot velocity of 0.1 m/s. This pioneering solution holds significant promise for diverse applications across various mobile robot configurations, presenting a compelling avenue for further exploration and implementation in the field.

Mapping wheelchair functions and their associated functional elements for stair climbing accessibility: a systematic review

PURPOSE

Wheelchair (WC) design elements are subjected to the accessibility and assistive needs of a person with locomotor disability. In order to pursue a holistic design for a stairclimbing WC, there is a need for literature review on WC functions reported for both stair climbing and plane surface movement.

METHODS

A total of 112 Research articles are reviewed for the purpose of extracting the relationship between WC design elements and the functions associated with them. Stairclimbing technologies are reviewed for their technological assessment in terms of functional elements associated with stairclimbing. Cross-functional mapping between functional elements and their dominant function is performed. Heat map for primary user needs and associated design elements is generated from cross mapping.

CONCLUSIONS

A design gap for user's functional needs is indicated from the review of literature on prototypes and products of WC. The literature in stairclimbing technology is primarily focussed on stair climbing capability and not on the other functional needs, such as safety, ride comfort, seat comfort, manoeuvrability, etc.Implications for rehabilitationFor attaining the goal of an effective rehabilitation, it is important to design and develop an assistive technology that can provide maximum accessibility and functioning for a person with disability. In case of locomotor disability, wheelchair (WC) is the most empowering tool that can assist people in both accessibility and activities of daily living. This review of literature was conducted to draw out the functions fulfilled by a WC, such as safety, comfort, propulsion for its users and the associated WC elements like seat, wheels, backrest, etc., that are required to fulfil those functions.WC being the most important technological intervention in the life of a person who cannot walk should be designed with the highest level of empathy. Therefore, each and every aspect of the user's physical and emotional needs should be catered up to the limits of engineering design. The research on stair climbing technologies has also grown exponentially, fuelled by technological growth in engineering mechanisms, ambient awareness sensors, actuators, etc. The review attempts to envelop such technologies and consolidate them on the basis of their capabilities and efficacies.The virtue of stair climbing has been realized through some novel and innovative mechanisms reviewed in this article that can be integrated with the research in field of functional elements required to carry out primary functions of a disabled person, such as safety, comfort, intuitiveness, etc. This review can help in coupling both of them in a more rational way where a designer who is designing the technology is more empathetic towards the design for accessibility. It can also help user in becoming more confident towards adapting a new assistive technology.

Evaluation of Power Wheelchair Dynamic Suspensions for Tip Prevention in Non-ADA Compliant Surfaces

OBJECTIVE

To evaluate the driving performance and usability of a mobility enhancement robot (MEBot) wheelchair with 2 innovative dynamic suspensions compared with commercial electric powered wheelchair (EPW) suspensions on non-American with Disabilities Act (ADA) compliant surfaces. The 2 dynamic suspensions used pneumatic actuators (PA) and electro-hydraulic with springs in series electrohydraulic and spring in series (EHAS).

DESIGN

Within-subjects cross-sectional study. Driving performance and usability were evaluated using quantitative measures and standardized tools, respectively.

SETTING

Laboratory settings that simulated common EPW outdoor driving tasks.

PARTICIPANTS

10 EPW users (5 women, 5 men) with an average age of 53.9±11.5 years and 21.2±16.3 years of EPW driving experience (N=10).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURE(S)

Seat angle peaks (stability), number of completed trials (effectiveness), Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST), and systemic usability scale (SUS).

RESULTS

MEBot with dynamic suspensions demonstrated significantly better stability (all P<.001) than EPW passive suspensions on non-ADA-compliant surfaces by reducing seat angle changes (safety). Also, MEBot with EHAS suspension significantly completed more trials over potholes compared with MEBot with PA suspension (P<.001) and EPW suspensions (P<.001). MEBot with EHAS had significantly better scores in terms of ease of adjustment (P=.016), durability (P=.031), and usability (P=.032) compared with MEBot with PA suspension on all surfaces. Physical assistance was required to navigate over potholes using MEBot with PA suspension and EPW suspensions. Also, participants reported similar responses regarding ease of use and satisfaction toward MEBot with EHAS suspension and EPW suspensions.

CONCLUSIONS

MEBot with dynamic suspensions improve safety and stability when navigating non-ADA-compliant surfaces compared with commercial EPW passive suspensions. Findings indicate MEBot readiness for further evaluation in real-world environments.

Evaluation of anti-rollback systems in manual wheelchairs: muscular activity and upper limb kinematics during propulsion

Self-propelling a wheelchair up a hill requires intense muscular effort and introduces the risk of the wheelchair rolling down. The purpose of this paper was to assess the user's muscular activity during ramp climbing. Tests were carried out on a group of 10 subjects who had to propel a wheelchair up a standardized wheelchair ramp. Basic parameters of upper limb kinematics were measured to determine the total push-rim rotation angle. This was 105.91° for a wheelchair with a stiff anti-rollback system, 99.39° for a wheelchair without an anti-rollback system and 98.18° for a wheelchair with a flexible anti-rollback system. The upper limb muscle effort was measured at 55 ± 19% for the wheelchair without an anti-rollback system, 59 ± 19% for the wheelchair with a stiff anti-rollback system and 70 ± 46% for the wheelchair with a flexible anti-rollback system. The conducted research showed an increase in muscle effort while using anti-rollback systems. In the case of push-rim rotation angle, no significant differences in the value of the rotation angle were found.

Manual Wheelchair Equipped with a Planetary Gear-Research Methodology and Preliminary Results

The purpose of the study was to create a research methodology for testing the newly developed wheelchair drive, which allows the operator to choose the gear ratio and, thus, makes it possible to change the propulsion torque value. The aim was to choose such conditions in the experiment, that would result in great enough changes in the participant’s muscle load and body kinematics for it to be possible to register them with applied measuring methods. Surface electromyography was used to assess the effort that was required for the propulsion of a wheelchair under different conditions. Additionally, upper limb motion capture measurements were also performed. The preliminary results show that the muscular effort of the participant propelling the wheelchair increases with the load—resulting from both the gear ratio and the inclination angle. At the same time, the position of the motion range of upper limb individual segments changes significantly. Simultaneously, the mean value of the shoulder displacement and its angle of rotation decreases.

Mini-review: Robotic wheelchair taxonomy and readiness

Robotic wheelchair research and development is a growing sector. This article introduces a robotic wheelchair taxonomy, and a readiness model supported by a mini-review. The taxonomy is constructed by power wheelchair and, mobile robot standards, the ICF and, PHAATE models. The mini-review of 2797 articles spanning 7 databases produced 205 articles and 4 review articles that matched inclusion/exclusion criteria. The review and analysis illuminate how innovations in robotic wheelchair research progressed and have been slow to translate into the marketplace.

Curb Negotiation With Dynamic Human-Robotic Wheelchair Collaboration

Wheelchair users often face architectural barriers such as curbs, limiting their accessibility, mobility, and participation in their communities. The mobility enhancement robotic (MEBot) wheelchair was developed to navigate over such architectural barriers. Its application allows wheelchair users to negotiate curbs automatically while the user remains in control. The application was optimized from a manual to a semiautomated process based on wheelchair users' feedback. The optimized application was evaluated by experienced wheelchair users who navigated over curbs of different heights. Participants evaluated MEBot in terms of effectiveness, workload demand, and usability. Ten participants successfully ascended and descended curbs of different heights at an average completion time of 55.7 ± 19.5 and 30.3 ± 9.1 s, respectively. MEBot maintained stability during the process, while participants reported low levels of effort, frustration, and overall cognitive demand to operate MEBot. Furthermore, participants were satisfied with the ease of learning and using the MEBot curb negotiation application to overcome the curbs but suggested less wheel adjustment for comfort and a faster pace to overcome curbs during real-world conditions.

Automated Curb Recognition and Negotiation for Robotic Wheelchairs

Common electric powered wheelchairs cannot safely negotiate architectural barriers (i.e., curbs) which could injure the user and damage the wheelchair. Robotic wheelchairs have been developed to address this issue; however, proper alignment performed by the user is needed prior to negotiating curbs. Users with physical and/or sensory impairments may find it challenging to negotiate such barriers. Hence, a Curb Recognition and Negotiation (CRN) system was developed to increase user's speed and safety when negotiating a curb. This article describes the CRN system which combines an existing curb negotiation application of a mobility enhancement robot (MEBot) and a plane extraction algorithm called Polylidar3D to recognize curb characteristics and automatically approach and negotiate curbs. The accuracy and reliability of the CRN system were evaluated to detect an engineered curb with known height and 15 starting positions in controlled conditions. The CRN system successfully recognized curbs at 14 out of 15 starting positions and correctly determined the height and distance for the MEBot to travel towards the curb. While the MEBot curb alignment was 1.5 ± 4.4°, the curb ascending was executed safely. The findings provide support for the implementation of a robotic wheelchair to increase speed and reduce human error when negotiating curbs and improve accessibility.

Evaluation of the Biomechanical Parameters of Human-Wheelchair Systems during Ramp Climbing with the Use of a Manual Wheelchair with Anti-Rollback Devices

Purpose: The main purpose of the research conducted was the analysis of kinematic and biomechanical parameters measured during manual wheelchair ramp-climbing with the use of the anti-rollback system and the comparison of the values tested with the manual wheelchair climbing the same ramp but without any modifications. The paper presents a quantitative assessment relating to the qualitative research of the anti-rollback system performed by another research team. Method and materials: The article presents the measurement results of the wheelchair motion kinematics and the activity of four upper limb muscles for eight subjects climbing a 4.58° ramp. Each subject propelled the wheelchair both with and without the anti-rollback system. The kinematic parameters were measured by means of two incremental encoders with the resolution of 500 impulses per single revolution of the measurement wheel. Whereas, the muscle activity was measured by means of surface electromyography with the use of Noraxon Mini DTS apparatus equipped with four measurement channels. Results: The surface electromyography measurement indicated an increase in the muscle activity for all four muscles, during the use of the anti-rollback system. The increase was: 18.56% for deltoid muscle anterior, 12.37% for deltoid muscle posteriori, 13.0% for triceps brachii, and 15.44% for extensor carpi radialis longus. As far as the kinematics analysis is concerned, a decrease in the measured kinematic parameters was observed in most participants. The medium velocity of the propelling cycle decreased by 26%. The ratio of the generated power and the loss power in a single propelling cycle λ had decreased by 18%. The least decrease was recorded for the measurement of mechanical energy E and the propelling cycle duration time. For the total mechanical energy, the decrease level was 3%, and for the propelling cycle duration it was 1%. The research carried out did not demonstrate any impact of the anti-rollback system use on the push phase share in the entire propelling cycle.

Proof-of-concept of a stair-climbing add-on device for wheelchairs

Motorized designs of stair-climbing wheelchairs available in western countries are heavy and expensive, and hence, unsuitable for developing countries. Manually operated solutions for stair-climbing wheelchairs also tend to be bulky and complex. As stair-climbing is an occasional activity for wheelchair users, having a built-in stair-climbing mechanism results in complexity and redundancy. In this work, an add-on device is envisaged, which requires the wheelchair to be mounted onto the add-on only when stair-climbing is needed. This work developed a Hex-wheel mechanism to address the demerits of the Y-wheel mechanism commonly used in load carriers, as well as to improve usability for stair-climbing. Furthermore, a suitably designed actuation mechanism was applied to the Hex-wheel to enable manual operation. Finally, a prototype of the stair-climbing add-on device was built to validate the developed mechanisms. The force required to operate the device was measured and found to be within 10% of the predicted theoretical value. The novel design provides a solution manually operable by an assistant, which is cost-effective and independent of wheelchair type to improve accessibility in low-resource settings.

A Heuristic Approach to Overcome Architectural Barriers Using a Robotic Wheelchair

The Mobility Enhancement roBotic (MEBot) wheelchair was developed to improve the safety and accessibility of wheelchair users when facing architectural barriers. MEBot uses pneumatic actuators attached to its frame and six wheels to provide curb ascending/descending for heights up to 20.3 cm. To improve MEBot's application, this study used a heuristic approach with power wheelchair users to evaluate and improve the MEBot application at different curb heights. Wheelchair users were trained on MEBot's features to operate its curb ascending/descending application. Three trials were carried out with wheelchair users ascending and descending three curbs of different height. Quantitative variables were analyzed to improve the sequential steps to ascend/descend curbs. Additionally, the application's effectiveness and efficiency were measured by the number of completed tasks, change in seat angle, and task completion time. Results showed that participants completed each trial and applied alternative strategies to traverse different curb heights. Furthermore, results suggested the combination and/or re-arrangement of steps to reduce task completion time. MEBot demonstrated its effectiveness to ascend/descend different curb heights with a heterogeneous participant sample. Future work will incorporate participant's most efficient strategies to improve the ascending/ascending process and the efficiency of the MEBot application.

Usability Evaluation of a Novel Robotic Power Wheelchair for Indoor and Outdoor Navigation

OBJECTIVE

To compare the Mobility Enhancement roBotic (MEBot) wheelchair's capabilities with commercial electric-powered wheelchairs (EPWs) by performing a systematic usability evaluation.

DESIGN

Usability in effectiveness, efficacy, and satisfaction was evaluated using quantitative measures. A semistructured interview was employed to gather feedback about the users' interaction with MEBot.

SETTING

Laboratory testing of EPW driving performance with 2 devices in a controlled setting simulating common EPW driving tasks.

PARTICIPANTS

A convenience sample of expert EPW users (N=12; 9 men, 3 women) with an average age of 54.7±10.9 years and 16.3± 8.1 years of EPW driving experience.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Powered mobility clinical driving assessment (PMCDA), Satisfaction Questionnaire, National Aeronautics and Space Administration's Task Load Index.

RESULTS

Participants were able to perform significantly higher number of tasks (P=.004), with significantly higher scores in both the adequacy-efficacy (P=.005) and the safety (P=.005) domains of the PMCDA while using MEBot over curbs and cross-slopes. However, participants reported significantly higher mental demand (P=.005) while using MEBot to navigate curbs and cross-slopes due to MEBot's complexity to perform its mobility applications which increased user's cognitive demands.

CONCLUSIONS

Overall, this usability evaluation demonstrated that MEBot is a promising EPW device to use indoors and outdoors with architectural barriers such as curbs and cross-slopes. Current design limitations were highlighted with recommendations for further improvement.

Enhancing the Trajectory Generation of a Stair-Climbing Mobility System

Recent advances in mobile robotic technologies have enabled significant progress to be made in the development of Stair-Climbing Mobility Systems (SCMSs) for people with mobility impairments and limitations. These devices are mainly characterized by their ability to negotiate those architectural barriers associated with climbing stairs (curbs, ramps, etc.). The development of advanced trajectory generators with which to surpass such architectural barriers is one of the most important aspects of SCMSs that has not yet been appropriately exploited. These advanced trajectory generators have a considerable influence on the time invested in the stair climbing process and on passenger comfort and, consequently, provide people with physical disabilities with greater independence and a higher quality of life. In this paper, we propose a new nonlinear trajectory generator for an SCMS. This generator balances the stair-climbing time and the user’s comfort and includes the most important constraints inherent to the system behavior: the geometry of the architectural barrier, the reconfigurable nature of the SCMS (discontinuous states), SCMS state-transition diagrams, comfort restrictions and physical limitations as regards the actuators, speed and acceleration. The SCMS was tested on a real two-step staircase using different time-comfort combinations and different climbing strategies to verify the effectiveness and the robustness of the proposed approach.