Kiyohiko Nunokawa

An experimental study on target recognition using white canes

To understand basic tactile perception using white canes, we compared tapping (two times) and pushing (two times) methods using the index finger and using a white cane, with and without accompanying auditory information. Participants were six visually impaired individuals who used a white cane to walk independently in their daily lives. For each of the tapping and pushing and sound or no sound conditions, participants gave magnitude estimates for the hardness of rubber panels. Results indicated that using a white cane produces sensitivity levels equal to using a finger when accompanied by auditory information, and suggested that when using a white cane to estimate the hardness of a target, it is most effective to have two different modalities of tactile and auditory information derived from tapping.

Influence of the Weight of White Canes on Muscle Load of the Upper Limbs

The purpose of this research is to clarify the influence of the weight of white canes on body load. More specifically, we conducted quantitative evaluations of the load on upper limb muscles when a white cane was manipulated over a long period of time, while the subject remained in a stationary standing position. The white canes used were a new type of white cane newly fabricated using aramid fibers, as well as a conventional type of white cane fabricated using carbon fibers. The results indicated that the newly developed cane reduced the load on the muscles by about 50% in comparison with the conventional type of cane. It became clear that it was possible to sustain the same posture even when used continuously over a long period of time.

A pilot study of a plantar sensory evaluation system for early screening of diabetic neuropathy in a weight-bearing position.

The purpose of this study is to develop smart equipment to quantify plantar tactile sensibility for the early diagnosis and tracking of peripheral neuropathy caused by diabetes mellitus. In this paper, we offer a new testing system that is composed of a plantar tactile stimulation platform with a small moving contactor to stretch the skin tangentially, a response switch for each tactile stimulus, a motor control box, and a personal computer (PC) for psychophysical data processing. This quantitative sensory testing system has detailed measurements available and is easy to use compared with the conventional testing devices, such as von Frey monofilaments, pin-prick testing devices, and current perception threshold testers. When using our testing system in a weight-bearing position, we observed that the plantar tactile thresholds for the tangential stretching stimulus on the plantar surface of the foot ranged from approximately 10 um to 30 um for healthy subjects. However, the threshold for a subject with diabetes was nearly three times higher than that for healthy subjects. The significant difference between these values suggests that the plantar sensory evaluation system using the lateral skin stretch stimulation can be used for early diagnosis, for the accurate staging of diabetic neuropathy, and for evaluating its progression noninvasively in a clinic and at home.

Evaluation of the variation in sensory test results using Semmes-Weinstein monofilaments.

The purpose of this study is to examine the variability in sensory test of tactile results using Semmes-Weinstein monofilament (SWM). At present, several methods for measuring the tactile sensitivity are clinically used in diabetic peripheral neuropathy screening. One of these methods is a touch test that uses a device with nylon SWMs, i.e., SWMs embedded in a plastic handle. A small pushing force is applied at the handle to bow the filaments. Because of its ease and simplicity, the SWM test is conducted at the patients bedside in a hospital. However, previous studies have reported some problems with this test. Studies have shown variations in the measured data, and it is uncertain whether these variations are caused by mechanical properties of the nylon fiber or by the motion of the operators hands. We carried out two experiments to examine the effect of (1) the variability caused by the human operator conducting the SWM test on the test results and (2) the number of compressions of the SWM on the test results. In experiment 1, we measured the velocity of the operators hand motion and the buckling force of the SWMs. The results showed variability in the hand motion of the operator conducting the SWM tests. In experiment 2, we measured the buckling force of the SWMs under a controlled velocity. We compared the buckling force of the SWMs through a number of trials. These results showed that the buckling force gradually decreases as the number of test cycles increase. In conclusion, we find that the accuracy of the SWM tests is a factor of the number of test cycles. Additionally, manual training for standardizing skills of medical staff members needs to be developed. Furthermore, the characteristics of the SWMs deteriorated over time. In future work, we aimto find a solution to minimize the variability in the SWM test results and develop a new testing system that uses tactile sensibility for diabetic peripheral neuropathy screening.

The Influence of the Manner of Grasping a White Cane on the Ability of Visually Impaired People to Perceive the Texture of Objects

This study examined the relationship between a surface’s texture (i.e., the particle size) and the perception of its roughness obtained from a white cane. The perception of roughness was measured by a magnitude estimation method with nine visually impaired people who used white canes. Their audiovisual information was restricted with eye masks and earmuffs. The perceived texture was investigated with three different styles of grasping the white cane: the index finger grasp, pencil grasp, and thumb grasp. Participants estimated the roughness of 18 waterproof abrasive papers with different particle sizes (6.7 to 279 μm). Because the exponent for this relationship was almost 0.35 for all three grasping styles when the particle size was small, it can be concluded that a small increase in the particle size causes a significant increase in the perceived roughness.

Influence of the Manner of Grasping a White Cane on the Ability of Visually Impaired Persons to Use These Canes for Estimating Object Weights

We have conducted research to obtain fundamental knowledge of the exploration methods used to perceive the characteristics of an object through contact with a white cane. The research has enabled us to examine methods that enhance the accuracy of perceiving objects and the materials and design of a white cane. In this study, we examine whether or not the method of grasping a white cane affects weight perception, with 5 visually impaired people who use white canes in their daily lives as participants. The participants provide estimates for the magnitudes of six weights ranging from 500 g to 1,000 g in steps of 100 g. Results indicate that weight can be determined using a white cane, even though this method is slightly inferior to directly pushing the weight by hand. The weight perception obtained by employing a white cane is not affected by the manner of grasping the cane.

Relationship between Weight of Our Developed White Cane and Muscle Load on the Upper Limbs during Swinging Action of the Cane

The present study aimed to investigate the influence of the weight of white canes on upper limb load. Concretely, we conducted quantitative evaluations of the load on upper limb muscles during swinging action of the cane. The white canes used were a new type of white cane newly fabricated using aramid fibers, as well as a conventional type of white cane fabricated using carbon fibers. The results indicated that the newly developed cane reduced the load on the muscles by about 50% in comparison with the conventional type of cane. It became clear that it was possible to sustain the same posture even when used continuously over a long period of time.