A primer for O&M specialists and trainers

I.  Introduction

Sunu band is an electronic travel aid (ETA) that intends to augment perception and awareness for blind and low vision individuals to objects or obstacles that are within the environment. It specifically enables users to detect obstacles that are at the upper-body level, those that can be missed by the white cane or guide dog. Sunu Band is a smartwatch and is worn around the wrist. It allows users to aim or scan the environment for obstacles. It uses haptic (vibration) feedback to alert how far or close the user is to an object. The user interprets the vibration feedback to safely navigate their spaces.

How Does Sunu Band Work

Sunu Band uses sonar or echolocation to detect objects that are as far away as 16ft (4.9 meters). It relays haptic vibration feedback that the user feels on their wrist. The vibration feedback allows users to know how far [or close] they are to a given object or obstacle. Users can point the Sunu Band in a given direction or scan their surroundings by slightly rotating their wrists inwards or outwards. 

Sunu Band connects via bluetooth to a mobile app for iOS and Android, though it can also be used as an ETA without the app. Users can update and customize the Sunu Band via the mobile app, as well as use its navigation features. 

Who is Sunu Band for

Sunu Band may be used by people who are blind, low vision and partially sighted. It is recommended for individuals who are interested in applying technology in their daily living and who want to complement their orientation and mobility. Sunu Band is a secondary layer of awareness to the individuals O&M skills and complements the cane and guide dog.

Sunu Band is recommended for children ages 10 and above. THe Sunu Band is only available in one size and can fit most wrist sizes, including men’s and women’s. Its strap is a standard 20 mm  watch belt and buckle and be replaced or substituted. 

II.  The sonar / obstacle detector and haptic feedback

How Sunu Band detects the environment

The Sunu Band detects objects that are within the user’s path using a sonar sensor and echolocation. The sonar sensor is directional. Think of it as a flashlight, except that it’s using ultrasound waves instead of light. For an object to be accurately detected, it must be:

1. Within range of the sonar.
2. In the direction to where the sonar is aiming.

The detection area is like the ‘field of view’ of the sonar sensor. Generally speaking, the Sunu Band’s sonar emits an ultrasound wave that propagates away from the sonar in the shape of a cone, at around 15 – 20 degrees. The wider the cone or detection area, the more ‘sensitive’ it is to objects, even those that are in the periphery and as thin (1cm) such as wires, tree branches etc. The narrower the cone or detection area, the less ‘sensitive’ it is to objects in the periphery. 

Sonar range is referred to as the maximum distance at which an object can be detected. Sunu Band uses distinct sonar modes which are optimal for certain environments:

• Short range or Indoor mode – can detect objects up to 6 feet (2 meters) in distance. This mode has a narrow detection area making it optimal for navigating indoors or crowded spaces and identifying corners, gaps and thresholds. 
• Long range  or outdoor mode – can detect objects up to 16 feet (5.5 meters) in distance. This mode has a wide detection area and is optimal for navigating outdoor spaces and detecting thin objects like tree branches, bushes and wires.

Getting to know the Haptic Vibration Feedback

Haptic feedback is the way in which we communicate information via vibration. The Sunu Band uses haptic vibrations to communicate proximity or distance – basically you feel pulses on your wrist that tell you how far or close you are to an obstacle. Sunu Band changes the frequency of the vibration pulses to provide you with a sense of how close an object is. Here is what happens to the vibration pulses when an object is detected and within range:

• No vibration pulses: means that there are no obstacles being detected. This also means that there is a free path and you may continue walking.
• Intermittent vibration pulses: means that the object being detected is sufficiently far away from you. You may continue approaching the obstacle or navigate your way around it.
• Moderate vibration pulses: means that the object being detected is now closer to you. You may navigate your way around it or continue approaching with caution.
• Constant Vibrations: the object is now within your personal space.

Using the Sunu Band’s Obstacle Detector

The Sunu Band may be worn on either the left or right hand. It may be used with or without a cane or guide dog. It is recommended that white cane users wear their Sunu Band on their non-dominant hand. There are two primary methods of detecting obstacles with Sunu Band. 

1. Pointing or at ‘fixed position’ – Is done by maintaining the sonar sensor aimed at a given direction. This is done because the user is only interested in knowing what obstacles are present within a particular direction in relation to his/her direction of travel. 

• Aiming Ahead – the sonar sensor is aimed in the direction directly ahead of the user. 
• Aiming to the Side – Is done when the user is interested in knowing about obstacles that my be to either their right-side or left-side. For example, when in sighted guide, the user may point the sonar to ‘unprotected’ side in order to maintain awareness and control.
• Upper Protective – The sonar is aimed upwards to protect against head-level objects like tree branches etc. This is done by slightly raising the hand and therefore raising the position of the sonar sensor.

2. Scanning or Sweeping – is done when the user wants to get a broader sense of objects that are within the environment. This is done by rotating the wrist inward and outward in a smooth and steady motion. Scanning with the ETA is the similar arching technique as done with the white cane (Hoover method). 

Interferences

It is possible to experience interference or ‘false positives’ when using the Sunu Band. The likely reasons for interferences occur because of the following:

• Clothing covering the sonar sensor. Long sleeve shirts or garments may cover the sonar sensor. The user will feel constant vibration because of it. 
• Ultrasound Emitting Devices. Automatic room lights that use proximity sensors will interfere with the Sunu Band. The constant vibration because of it. 
• Overarching scanning. Mostly happens when the user rotates their wrist inward too much, to the point where the sonar is pointed at their own body. The user may also detect their own white cane or guide dog. Therefore, it is important to practice and know the limit to where the user can accurately perform the scanning technique.