Sonar for the visually impaired - UX ideas

Projects / Project Swiftlet  Original post date:07/09/2015 “Show Us Your Human Interface”

This was one of the things on my mind, but I didn't write it down in a specific section. I guess the “Show Us Your Human Interface; Win Laser Cutting Time” is a good incentive for that.

Since this device is designed to operated with a visually impaired person, the user interface is a bit different than most. The device is equipped with dual haptic motors and dual speakers that can be used to communicate with the user for environmental and navigational information.

Informational messages

The dual haptic motors can be used to give directional information such as left or right based on which of the motor is energized. The frequency of the pulses can be used as analog feedback such as closing of distances.

In the sonar mode, the raw ultrasonic signal is slowed down by a factor of 20X, this gives the user access to the analog echo signals and motion detection via dopper effects. (more details here)

The following picture shows the raw echo signals that can detect objects/boundary at multiple distances - (large blip) door threshold, (small blip) door and (large blip) far end wall. (project log here) These type of information is not available if you use the ultrasonic range finder module as is and hook up the 4 pin interface to a microcontroller. The module would only return the first echo and ignore everything else.

Research paper has shown that a person can be trained to process these signals to get an overall 

"Results: Naive subjects were able to make laterality and distance judgments, suggesting that the echoes provide innately useful information without prior training. Naive subjects were generally unable to make elevation judgments from recorded echoes. However, trained subjects demonstrated an ability to judge elevation as well."

The SPI FLASH memory can hold voice samples for words for constructing short messages 

numeric measurements such as distances, height/depth, battery voltage, temperature

direction: N/E/S/W, left/right, bearing

warning message: stop, proximity alert

Interactive User Menu

The accelerometer used in this device was designed for a mobile device and can sense single/double tab (pulse of acceleration) to bring up user interface. The same function can be used in this device.

• A single tap can be used to bring up frequent used function such as a sonar ping.
• A double tap can be used for is to bring up a more complex voice prompted menu, where by the user can navigate by simple head motion.

• Nodding/shaking head can be interpret as Yes/No answer to a question. These can be detected by the 3-axis accelerometer.

• The amount of head turning or nod can be used as analog value for adjusting options.

The orientation of the device such as facing down or lack of motions can be used to tell the device to go into sleep mode.

Debugging

For firmware debugging, I intend to use a LCD graphic display with the Alien movie "Tracker" style user interface which is exactly the type of display to show echos. A polar plot + a few line of text can show the echo and orientation information. I wonder if this can be also be sold as a toy/novelty item.