Low-Cost Ultrasonic Range Improvements for an Assistive Device

Abstract

To achieve optimal mobility, visually impaired people have to deal with obstacle detection and avoidance challenges. Aside from the broadly adopted white cane, electronic aids have been developed. However, available electronic devices are not extensively used due to their complexity and price. As an effort to improve the existing ones, this work presents the design of a low-cost aid for blind people. A standard low-cost HC-SRF04 ultrasonic range is modified by adding phase modulation in the ultrasonic pulses, allowing it to detect the origin of emission, thus discriminating if the echo pulses come from the same device and avoiding false echoes due to interference from other sources. This improves accuracy and security in areas where different ultrasonic sensors are working simultaneously. The final device, based on users and trainers feedback for the design, works with the user’s own mobile phone, easing utilization and lowering manufacturing costs. The device was tested with a set of twenty blind persons carrying out a travel experiment and satisfaction survey. The main results showed a change in total involuntary contacts with unknown obstacles and high user satisfaction. Hence, we conclude that the device can fill a gap in the mobility aids and reduce feelings of insecurity amongst the blind.

Low-cost ultrasonic sensors for in-field experimentation data collection

“…The results of calibration presented high correlations, the R² = 0.99 showed good precision the values, corresponding already observed to Abreu et al (2021), Therefore, the results calibrations showed values R² near the one with anothers sensors, whose calibrations were greater than 0.9 of the coefficients of determination (Sanches et al, 2020;2022b). Subsequently, a statistical analysis was performed using the obtained results, as shown in Table 5.…”

Sound Feedback for Social Distance: The Case for Public Interventions During a Pandemic

“…In hindsight, the placement of the sensors of the face, constantly shifting their projected angles meant that misreadings were highly probable. When tested in lab conditions, these proximity sensors are expected to perform reliably at differing trajectories [115], but when we inspect the sound recording and video footage, we observed many cases of unexpected readings during the performances in contrast to the testing phase. Participants would move closer together with no perceivable feedback.…”

“…The range and accuracy benchmarks for the ultrasonic sensors are partially dependent on environmental variables such as ambient temperature and humidity. When working in typical indoor conditions, the ultrasonic sensors are expected to ensure a stable accuracy of up to 13 feet (4 metres), within a 15 • degree angle [115].…”

Sound Feedback for Social Distance: The Case for Public Interventions during a Pandemic

“…In hindsight, the placement of the sensors of the face, constantly shifting their projected angles meant that misreadings were highly probable. When tested in lab conditions, these proximity sensors are expected to perform reliably at differing trajectories [116], but when we inspect the sound recording and video footage, we observed many cases of unexpected readings during the performances in contrast to the testing phase. Participants would move closer together with no perceivable feedback.…”

“…The range and accuracy benchmarks for the ultrasonic sensors are partially dependent on environmental variables such as ambient temperature and humidity. When working in typical indoor conditions, the ultrasonic sensors are expected to ensure a stable accuracy of up to 13 feet (4 m), within a 15 degree angle [116].…”