Nicholas Stewart, Justin LaMar, Christine Lochner, Kayla Cole, Lindsay Johnson, and Emeka Akpaka [Left to right]
ABSTRACT
Individuals who have a reduced ability to hear and see may find that everyday tasks such as walking are challenging. To address these challenges, the project team has iteratively designed a user-friendly cane handle that improves user independence by providing haptic signal-detection feedback. Key attributes of this product are its affordability compared to alternative canes on the market and its unique non-auditory feedback. A series of tests are being performed on the cane to ensure that it meets functionality requirements along with being a desirable cane for intended users.
INTRODUCTION
Individuals with visual impairments face daily challenges in regards to interacting with and navigating through their environments. While some support systems exist in the form of assistive devices, most of these solutions provide audio feedback to the user to alert them of obstacles in their surroundings. This solution does not offer support for deaf-blind users or for hard-of-hearing users trying to navigate through obstacle-ridden environments.
The cane designed by this senior design team is an advanced assistive device that improves a deaf-blind user’s ability to detect obstacles and navigate more safely by increasing detection range. In contrast to the auditory design, the cane relies on tactile signals to guide the user. Current canes on the market that provide haptic feedback are upwards of 600 USD and our customer base is seeking a more affordable option that is comfortable to use and has accurate feedback signals that are intuitive or easy to learn.
PROBLEM STATEMENT
The team needs to design and develop a working cane prototype for deaf-blind users that is competitive in the market with a low manufacturing cost. It must be able to detect obstacles, provide users with haptic feedback from the cane handle, be rechargeable for user convenience, be lightweight to avoid strain, and can be easily collapsed into segments for portability.
METHODOLOGY/APPROACH
Handle Frame
The shell of this handle is composed entirely of polylactic acid [PLA] material with a 50 percent infill and is displayed in Figure 2. Its purpose is to provide a lightweight solution that has a good layer bond to provide strength. The choice of PLA also provides a solution that is weather-resistant as the material is insoluble in water. A user is able to comfortably grip this cane handle while sweeping the cane side-to-side. Per the current cane standard, one side of the cane handle has a straightedge to ensure that a user holds the cane in the proper orientation.
Power
To power-on the cane, a user moves a horizontal switch from left to right. Based on the final battery selected, the cane is expected to function for at least 8 consecutive hours and it is fully rechargeable. Convenient charging is provided by a microUSB port that is directly on the cane.
Signal Detection
The selected sonar sensor provides an obstacle detection range that goes as far as 9.25 feet from the sensor mount point of the cane, thus making the total detection range larger than ten feet. It provides a desirable vertical detection range of 4 feet and is able to detect objects within a 180 degree radius as the user sweeps the cane from side-to-side. When an object is detected, the accelerometer indicates whether the obstacle is on the left or right side of the user and provides that information to a microprocessor. A signal is then sent from the microprocessor to the two motors.
Motors and Bearings
Each of the motors serves to rotate the bearing side-to-side on one side of the cane handle. One bearing contacts the palm of the hand while the other touches the user’s fingers. Such placement ensures that, while the user holds the cane in a way that mimics the traditional cane-handling technique, the haptic feedback can be easily felt. When users feel a bearing move in their hand, they intuitively know whether the obstacle is on the right-hand or the left-hand side as feedback side is identical to obstacle location side (i.e. Either to the left or right of the user).
Figure 4 displays one bearing armature that provides feedback to the user by rotating the roller and bearing side-to-side. Two bearing armatures are included in the cane handle and each corresponds to detection of an obstacle on one side of the user.
RESULTS & DISCUSSION
The completed prototype will represent a traditional white cane with the standard handle replaced by the team’s obstacle-detecting handle. A new handle will allow a user to detect obstacles within a horizontal plane while the user sweeps the cane. A detection range of over 9 feet will allow the cane’s sensor to detect an obstacle and send feedback to the user in time to allow for obstacle avoidance. Haptic feedback in the cane handle will indicate that an obstacle exists on one side of the user. Having the haptic feedback will effectively increase a user’s ability to be independent as they will feel confident in their ability to detect and avoid obstacles that could potentially be tripping hazards.
Feedback testing will be performed at ABVI of Rochester, NY because that site allows the team to test cane functionality with users who are currently blind. The team also has access to potential users because RIT deaf or hard-of-hearing students at NTID can test the cane. To test signal detection, the user will go through an obstacle course while sweeping the cane and observers will take notes. A user will verbally indicate whether the feedback could be felt and whether it was easy to comprehend. Safety of the device must also be considered during the testing phase. Since the cane operates using a battery and two motors, heat tests will be implemented to ensure that no harm due to overheating will exist.
In addition to being functional, the cane will be exceptionally user-friendly. It will be collapsible into four, 12.5” segments and the time required to collapse or reassemble the cane is less than 10 seconds. This provides convenience as the user is able to more easily store the cane when it is not in use. Also, the battery life of at least 8 hours allows the user to take advantage of the cane’s benefit for a full workday, if needed. Use of a rechargeable battery is convenient for users who may not be interested in purchasing and installing several batteries over time. Since the cane is intended to be used for a wide range of durations, the team has ensured that the additional weight of the new handle increases the cane’s weight by less than one pound.
Cost Implications
Design for manufacturability was taken into account when finalizing cane design decisions. The cane’s handle is a 3D printout for our prototype, but it will be injection molded when it goes into production. The proposed design has a total bulk manufacturing cost of 136.05 USD. Injection molding, overhead, general, and administrative costs will depend on where the cane is produced and on the volume produced. For manufacturing costing, ordering in bulk is presumed to require 500 pieces and all values are quotes from external vendors.
Market potential is strong for this product as it is a lower-cost option than others on the market and it has the unique ability to be used by deaf-blind users. Our product was designed with the market in mind and we have ensured that its specifications meet current industry standards. Since all components are currently available from vendors, there is no additional work required from a sourcing perspective.
ACKNOWLEDGEMENTS
The team greatly appreciates the help of Dr. Iglesias for her assistance with design support and purchasing, Tom Oh and Carlos Barrios for their electrical design insights, and Gary Behm for patenting this idea and encouraging us to make his dream a reality. We would also like to thank our guide Charlie Tabb for his mentorship throughout this 32 week journey and Joe Kells and Nikki Llewellyn from ABVI for providing us with prototype test personnel, subject matter expert support on low-vision user needs, and financial support for the project. Denis Cormier had an integral role in providing design for manufacturability and design for assembly insights. We would like to thank both Denis and Mike Bufflin for their 3D printing knowledge and for helping us create a great prototype of the cane handle shell. Lastly, we are happy to have the help of our university’s senior design staff who gave us guidance throughout the project.