A belt-like assistive device for visually impaired people: Toward a more collaborative approach

Figures & data

Figure 1. Flowchart of the development process.

Table 1. Survey 1—Needs assessment

Item	Question
#1	Do you know any electronic assistance device for VI people? Please name it/them
#2	Which features do you consider that an electronic assistance device should include?
#3	If the system was wearable, how would you like to use it?

Figure 2. Arrangement of the sensors used for the proposed system. Gray-shaded areas represent the sensors’ sensing fields.

Figure 3. Flowchart of the proposed system operation. Thresholds for detecting obstacles at the head, trunk and foot level are denoted as “thr_H”, “thr_T”, and “thr_F”, respectively. The threshold for drop-off detection is denoted as “thr_D”.

Table 2. Threshold values for obstacle detection and identification

Obstacle location	Threshold (cm)
Head-level obstacle	267.3
Trunk-level obstacle	242.3
Foot-level obstacle	255.4
Drop-off	110.0

Figure 4. Electric diagram of the circuit for the proposed system.

Figure 5. The external appearance of the proposed system. Values are expressed in centimeters.

Figure 6. Scenarios for the first (a) and the second navigation test (b). The empty and filled circles denote the starting and ending points, respectively. Distances between obstacles were more than 5 meters.

Table 3. Survey 2—Performance assessment

Item	Statement
#1	The system is comfortable
#2	The system is easy to use
#3	The alarms provided by the system are intelligible and reliable

Figure 7. Front view (a) and back view (b) of the proposed system.

Table 4. Results of the first survey: VI users’ opinions (n = 15)

Item	Question	Total answers
#1	Do you know any electronic assistance device for VI people?	Yes	4
		No	11
#2	Which features do you consider that an electronic assistance device should include?	Obstacle detection alarms	7
		Easy to use	7
		Comfortable	6
		Affordable	4
		Aesthetically pleasant	2
#3	If the system was wearable, how would you like to use it?	Like a hat	1
		Like a belt	11
		Like a vest	3

Table 5. Detection results for the first test. The “X” denotes successful detection

TrialObstacle level	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	#11	#12
Head	X	X	X	X	X	X	X	X	X	X	X	X
Trunk	X	X	X	X	X	X	X	X	X	X	X	X
Foot	X	X	X	X	X	X	X	X	X	X	X	X

Table 6. Detection results for the second test. The “X” denotes successful detection

TrialObstacle level	#1	#2	#3	#4	#5	#6	#7	#8	#9	#10	#11	#12
Head	X	X	X	X	X	X	X	X	X	X	X	X
Trunk	X	X	X	X	X	X	X	X	X	X	X	X
Foot	X	-	X	X	-	-	X	X	-	X	X	X
Drop-off	X	X	X	X	X	X	X	X	X	X	X	X

Table 7. Results of the second survey: VI users’ opinions (n = 12)

StatementLevel ofagreement	The system is comfortable	The system is easy to use	The alarms provided by the system are intelligible and reliable
Totally agree	100.0%	83.3%	66.7%
Partially agree	0.0%	16.7%	33.3%
Indifferent	0.0%	0.0%	0.0%
Partially disagree	0.0%	0.0%	0.0%
Totally disagree	0.0%	0.0%	0.0%

Table 8. Our system compared with similar studies (NR: not reported)

Reference	Did researchers involve users during the development process?	Does the device provide users with directional information?	Does the device provide users with obstacle height information?	Cost (USD $)
Shoval et al., 1998	No	Yes	No	NR
Tsukada & Yasumura, 2004	No	Yes	No	NR
Bhatlawande et al., 2012	No	Yes	Yes	280,00
Katzschmann et al., 2018	No	Yes	Yes	1450,00
This study	Yes	No	Yes	250,00

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