Drop-off detection with the long cane: effect of cane shaft weight and rigidity on performance

Contribution of Vibration, Tapping Sound, and Reaction Force to Hardness Perception During Indirect Tapping Using a White Cane

This study aimed to identify the physical factors contributing to the perception of the hardness of objects tapped using white canes, which are commonly used by the visually impaired for autonomous walking. First, physical factors such as vibration tapping sounds and reaction forces were measured during the indirect tapping of rubber sheets with different hardness using a white cane. Second, we determined the relationship between the subjective hardness perceived by the visually impaired individuals and the physical factors through multivariate analysis. In addition, we estimated the contribution of each factor. The result indicates that the white cane vibrated at similar frequencies during tapping even when the hardness of objects changed. In contrast, the tapping sound varied widely with the variation of the hardness of the rubber sheet. In addition, the peak values of the reaction forces significantly changed depending on the hardness. Based on the results of the multivariate analysis, the contributions of tapping sounds and reaction forces to hardness perception were remarkable. In contrast, the contributions of vibrations could not be found using our analytic method. These findings will help in the design and evaluation of support equipment for the visually impaired.

Multimodal sensing and intuitive steering assistance improve navigation and mobility for people with impaired vision

Globally, more than 250 million people have impaired vision and face challenges navigating outside their homes, affecting their independence, mental health, and physical health. Navigating unfamiliar routes is challenging for people with impaired vision because it may require avoiding obstacles, recognizing objects, and wayfinding indoors and outdoors. Existing approaches such as white canes, guide dogs, and electronic travel aids only tackle some of these challenges. Here, we present the Augmented Cane, a white cane with a comprehensive set of sensors and an intuitive feedback method to steer the user, which addresses navigation challenges and improves mobility for people with impaired vision. We compared the Augmented Cane with a white cane by having sighted and visually impaired participants complete navigation challenges while blindfolded: walking along hallways, avoiding obstacles, and following outdoor waypoints. Across all experiments, the Augmented Cane increased the walking speed for participants with impaired vision by 18 ± 7% and sighted participants by 35 ± 12% compared with a white cane. The increase in walking speed may be due to accurate steering assistance, reduced cognitive load, fewer contacts with the environment, and higher participant confidence. We also demonstrate advanced navigation capabilities of the Augmented Cane: indoor wayfinding, recognizing and steering the participant to a key object, and navigating a sequence of indoor and outdoor challenges. The open-source and low-cost design of the Augmented Cane provides a platform that may improve the mobility and quality of life of people with impaired vision.

Environmental information for people with visual impairment in Mexico - or what they need and how they use it

From an ergonomics perspective, the environmental characteristics should facilitate user activities. Matching user capabilities to demands of the environment is essential. However, about some users such as those with visual impairments, there is little information available for use in designing products and spaces. There is also a gap in information regarding the commutes and needs of the visually impaired, making it even more difficult to establish how environments should be designed to include this population.This study aimed to identify the information needs of people with visual impairment in terms of: 1) Daily life activities, 2) Wayfinding in the complex built environments, 3) Use of the signals provided by the environment 4) Characteristics of the environment which reduce the usability of a space and may put the user in danger, and 5) Safety perception. Data were obtained through a semi-structured interview to which eighteen adults responded. All had either complete blindness or severe visual impairment. For orientation, the most common references were texture or changes in ground level/surface, along with such ambient elements as noise or smells. Information presented in Braille was reported as little used, due to difficulty in finding such information. Regarding safety, participants reported feeling unsafe; most mentioned crossing the street as a major risk. Using auditory, tactile or even olfactory signals may provide important information while commuting: thus, designing signals which consider and highlight these senses is paramount. Assessing features and location of existing tactile signals is also required, to identify opportunities for improving the safety and independence of people with visual impairment.

Biomechanics of Long Cane Use

Introduction

The modern long cane has been used by people who are blind for traveling for decades. This article describes parameters surrounding the collection of over 10,000 trials of people walking with the long cane to detect drop-offs or obstacles.

Methods

The data include 10,069 trials representing 101 different participants in 366 conditions over 11 studies spanning the 9 years from 2007 to 2016. Each of the studies investigated different participant or cane characteristics or both in terms of their effect on either drop-off or obstacle detection. Results of detection performance in these studies appear in other articles. This article describes biomechanical measures derived from 3-D motion analysis equipment used during the studies.

Results

Initial treatment of the large data set indicated that participants tended to not center their cane arc laterally on their body, deviating up to about 20 centimeters from midline. Arc widths averaged almost a meter, and arcs were generally centered. Participants were generally poor at being in step or having consistent rhythm. Coverage rates averaged about 85%.

Discussion

Although participants might have demonstrated artificially high skill performance due to being in a research study, data do offer insights into mechanical performance of skills. This survey of the data set indicates that not centering the hand holding the cane does not decrease body coverage less than about 85%. However, further analyses will be conducted to delve more deeply into all aspects of the data.

Implications for practitioners

Basic cane skills can be taught with short sessions and massed practice. Novices can acquire basic cane skills on par with cane users who are blind, but individual differences exist and the interplay of biomechanical variables needs to more fully understood.

Obstacle Detection with the Long Cane: Effect of Cane Tip Design and Technique Modification on Performance

INTRODUCTION

The purpose of this study was to investigate the effect of cane tip design and cane technique modification on obstacle detection performance as they interact with the size, height, and position of obstacles.

METHODS

A repeated-measures design with block randomization was used for the study. In experiment one, participants attempted to detect obstacles with either a marshmallow tip or a bundu basher tip. In experiment two, participants were asked to detect obstacles using either the constant-contact technique or a modified constant-contact technique.

RESULTS

As predicted, the obstacle detection rate with the bundu basher tip (M = 66.1%, SD = 7.4%) was significantly higher than that with the marshmallow tip (M = 54.6%, SD =6.8%), F(1, 11) = 24.19, p < .001, r = .83. However, contrary to our hypothesis, the obstacle detection rate with the modified constant-contact technique (M =56.0%, SD = 7.4%) was significantly lower than that with the constant-contact technique (M = 61.3%, SD = 5.2%), F(1, 13) = 6.49, p = .024, r = .58. In addition, participants detected the obstacles that were positioned at the center of their walking path (M = 61.9%, SD = 6.6%) at a significantly higher rate than those positioned slightly off to the side (M = 55.4%, SD = 7.3%), F(1, 13) =10.73, p = .006, r = .67.

DISCUSSION

A bundu basher tip was more advantageous than the marshmallow tip for detecting obstacles.

IMPLICATIONS FOR PRACTITIONERS

Given the findings of the study, cane users and orientation and mobility (O&M) specialists should consider using or recommending a bundu basher tip (or a similar tip that has an increased contact area with the walking surface), particularly when the traveling environment often presents unexpected obstacles that may trip the cane user.

Effect of cane length and swing arc width on drop-off and obstacle detection with the long cane

A repeated-measures design with block randomization was used for the study, in which 15 adults with visual impairments attempted to detect the drop-offs and obstacles with the canes of different lengths, swinging the cane in different widths (narrow vs wide). Participants detected the drop-offs significantly more reliably with the standard-length cane (79.5% ± 6.5% of the time) than with the extended-length cane (67.6% ± 9.1%), p <.001. The drop-off detection threshold of the standard-length cane (4.1 ± 1.1 cm) was also significantly smaller than that of the extended-length cane (6.5±1.8cm), p <.001. In addition, participants detected drop-offs at a significantly higher percentage when they swung the cane approximately 3 cm beyond the widest part of the body (78.6% ± 7.6%) than when they swung it substantially wider (30 cm; 68.5% ± 8.3%), p <.001. In contrast, neither cane length (p =.074) nor cane swing arc width (p =.185) had a significant effect on obstacle detection performance. The findings of the study may help orientation and mobility specialists recommend appropriate cane length and cane swing arc width to visually impaired cane users.