Fausto Orsi Medola

Aspects of Manual Wheelchair Configuration Affecting Mobility: A Review

Many aspects relating to equipment configuration affect users’ actions in a manual wheelchair, determining the overall mobility performance. Since the equipment components and configuration determine both stability and mobility efficiency, configuring the wheelchair with the most appropriate set-up for individual users’ needs is a difficult task. Several studies have shown the importance of seat/backrest assembly and the relative position of the rear wheels to the user in terms of the kinetics and kinematics of manual propulsion. More recently, new studies have brought to light evidence on the inertial properties of different wheelchair configurations. Further new studies have highlighted the handrim as a key component of wheelchair assembly, since it is the interface through which the user drives the chair. In light of the new evidence on wheelchair mechanics and propulsion kinetics and kinematics, this article presents a review of the most important aspects of wheelchair configuration that affect the users’ actions and mobility.

Partitioning Kinetic Energy During Freewheeling Wheelchair Maneuvers

This paper describes a systematic method to partition the kinetic energy (KE) of a free-wheeling wheelchair. An ultralightweight rigid frame wheelchair was instrumented with two axle-mounted encoders and data acquisition equipment to accurately measure the velocity of the drive wheels. A mathematical model was created combining physical specifications and geometry of the wheelchair and its components. Two able-bodied subjects propelled the wheelchair over four courses that involved straight and turning maneuvers at differing speeds. The KE of the wheelchair was divided into three components: translational, rotational, and turning energy. This technique was sensitive to the changing contributions of the three energy components across maneuvers. Translational energy represented the major component of total KE in all maneuvers except a zero radius turn in which turning energy was dominant. Both translational and rotational energies are directly related to wheelchair speed. Partitioning KE offers a useful means of investigating the dynamics of a moving wheelchair. The described technique permits analysis of KE imparted to the wheelchair during maneuvers involving changes in speed and direction, which are most representative of mobility in everyday life. This technique can be used to study the effort required to maneuver different types and configurations of wheelchairs.

A new design for an old concept of wheelchair pushrim

Purpose: Report on the development of an ergonomic manual wheelchair pushrim and evaluate the user’s perception of the quality of the device. Method: Based on anthropometric features and ergonomic concepts, a new wheelchair pushrim was designed, and a prototype was manufactured in polyurethane, using the rapid prototyping technique and serial production of parts by molding. The prototype was tested by a sample of wheelchair users, who rated the perceived quality of the device after testing both the new and conventional pushrims in a wheelchair propulsion experimental protocol. Results: The new ergonomic pushrim was found to be, in general, better than the conventional round tube pushrim. Specifically, experienced wheelchair users found the new wheelchair pushrim better in terms of easy and comfortable propulsion, braking and maneuvering of the wheelchair, and appearance. Conclusions: The new wheelchair pushrim provides a proper fit for the hands due to its ergonomic design and its polyurethane composition, making wheelchair propulsion easier and more comfortable than the conventional wheelchair pushrim. Assistive technology devices should be design based on ergonomic concepts that involve less effort and offer greater comfort for the user. Implications for Rehabilitation Manual wheelchair propulsion has been related with upper limb injuries that may potentially limit functionality. The conventional pushrim does not meet the need for a firm and stable grip, requiring further effort to hold the pushrim during manual propulsion that may cause discomfort, pain and contribute for developing upper limb injuries. In a relatively small sample of wheelchair users, this study shows that an ergonomically designed pushrim makes manual propulsion easier and more comfortable compared to the conventional pushrim.

Exploring Russian Tap-Code Text Entry Adaptions for Users with Reduced Target Hitting Accuracy

Text is still the dominant form of human-computer-human communication. Users with certain motor or visual impairments may be unable to use certain text entry interfaces such as the small virtual keyboards on mobile phones effectively due to challenges hitting small targets. Despite the vast amount of research into text entry, no efforts have explored the so-called Russian tap-codes, or knock codes, which were commonly used to communicate between prison inmates. Tapping does not require the user to hit a specific target. This study proposes a theoretical framework for classifying text entry designs. The framework is used to explore 16 text entry designs, namely the classic Russian tap code and design variations exploiting more recent results in text entry research and the context of current hardware, allowing unfeasible designs to be easily eliminated.

Supporting Collaborative Ideation Through Freehand Sketching of 3D-Shapes in 2D Using Colour

The modelling of 3D shapes is a challenging problem. Many innovative approaches have been proposed, however most 3D software require advanced skills that hinders collaboration and spontaneous ideation. This paper proposes a novel framework that allows designers to express their ideas in 3D space without extensive training such that they can reuse their 2D sketching skills collaboratively in teams.

The influence of seat height, trunk inclination and hip posture on the activity of the superior trapezius and longissimus.

[Purpose] This study was aimed at investigating the influence of seat height and body posture on the activity of the superior trapezius and longissimus muscles. [Subjects and Methods] Twenty two healthy subjects were instructed to perform a total of eight different body postures, varying according three main factors: seat height (low and high seat); trunk inclination (upright and leaning forward at 45°); and the hips in abduction and adduction. Electromyography of the superior trapezius and longissimus was collected bilaterally, and the average values were obtained and compared across all the postures. [Results] The activity of the superior trapezius and longissimus significantly changes according to the seat height and trunk inclination. For both seat heights, sitting with trunk leaning forward resulted in a significant increase in the activity of both muscles. When sitting in a high seat and the trunk leaning forward, the superior trapezius activity was significantly reduced when compared to the same posture in a low seat. [Conclusion] This study contributes to the knowledge on the influence of the body posture and seat configuration on the activity of postural muscles. Reducing the biomechanical loads on the postural muscles must be targeted in order to improve users’ comfort and safety.

Using a Pressure Mapping System to Evaluate Contact Pressure on Hands During Use of Axillary Crutches.

The aim of this study was to evaluate different handles used in axillary crutches with a Pressure Mapping System. The Grip Versatek system from Tekscan Inc. was used to measure the levels and the distribution of contact pressure in the hands during a simulated activity of ambulation with crutches. The sample included ten able-bodied subjects: five men and five women. The results show that the different models of handles appear to have influenced the pressure levels measured during the activity. Therefore, the measurement equipment provides parameters that allow the comparison among different designs and assess their contribution to the comprehension of the demands of ergonomic handles.

Accessibility and Usability of Websites Intended for People with Disabilities: A Preliminary Study

This paper reports a preliminary study evaluating accessibility and usability of a Brazilian government website - the national digital catalogue of assistive technology (CNPTA). Although since 2004 e-government information should be broadly accessible, several studies indicate that web accessibility has not been accomplished in many government websites. This study is part of a research project that analyses whether this negative outcome replicates on government websites intended for people with disabilities. The website was assessed by automated testing and the results were compared to the outcomes from user testing. The paper discusses the findings compared with past studies and not only proposes specific aspects to enhance the website, but also it outlines several points to be considered in the next steps of the research project, as well as in other research that considers web accessibility and usability for blind people.

A new walking aid with axillary support for children with cerebral palsy: electromyographic evaluation

Abstract Purpose: To present a new walking aid with axillary support (WAAS) for children with cerebral palsy (CP) and to investigate its impact on the lower limb muscles activation in the gait of children with CP. Method: Six children with spastic diparesis due to CP performed a straight line walking course in two situations: with and without using the WAAS. Each course was repeated three times for both situations, and electromyography (EMG) activity of quadriceps, hamstrings, tibialis anterior and gastrocnemius were recorded during all trials. Results: The use of WAAS significantly increased the EMG activity of the quadriceps and hamstrings during stance phase and tibialis anterior during swing phase, with no significant increase in gastrocnemius activation. Conclusion: The use of WAAS improved the synergism of lower limbs muscles of children with CP by reducing the coactivation of antagonistic muscles, especially during the swing phase of gait. Providing a walking aid with improved trunk stability may enable children with CP to improve muscular synergism and walking ability, thus favoring independent mobility, with possible gains in social participation and quality of life. Implications for Rehabilitation Children with cerebral palsy have problems with the development of normal gait, as a result of the reduced motor control and the impaired muscle synergism of the lower limbs. Standard walking aids do not provide proper trunk stability for this group of children. In a relatively small sample of children with cerebral palsy, a walking aid with axillary support was shown to be beneficial for the muscular synergism of the lower limbs during gait.

Multi-switch Scanning Keyboards: A Theoretical Study of Simultaneous Parallel Scans with QWERTY Layout

Scanning keyboards can be useful aids for individuals with reduced motor function. However, scanning input techniques are known for being very slow to use because they require waiting for the right cell to be highlighted during each character input cycle. This study explores the idea of parallel scanning keyboards controlled with multiple switches and their theoretical effects on performance. The designs explored assume that the keyboard layouts are familiar to users and that the mapping between the switches and the keyboards are natural and direct. The results show that the theoretical performance increases linearly with the number of switches used. Future work should perform user tests with parallel scans to assess the practicality of this approach.