LY02a-21 FPGA-controlled Single Refreshable Braille Character

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YAN, Kai Hang(@khyan)
January 19, 2022 3:14 pm

Good afternoon. From the niche and solution I saw that the aim of this project is to create a portable and affordable braille display for visually impaired users.
Is there any compare between the traditional solution and your product? (Maybe in cost and weight/size) and why your project has such improvement?


CHAN, Cheuk Yu(@cychancq)
January 19, 2022 3:28 pm
Reply to  YAN, Kai Hang

Thank you for your question. Conventional commercial refreshable Braille devices (RBD) usually include more than one Braille character cell, ranging from 20 to 80 Braille cells, designed to sit on the users’ desk and cost ranging from USD $3500 to USD$15000. These devices uses are mostly associated with piezoelectric devices to actuate the motors for driving the elevation of pins.Using piezoelectric devices poses a high material cost and complexity of circuit design, which may introduce higher selling prices of the products. Portability of these devices is also an issue, as including multiple Braille character cells would cause larger size of the device.

Our solution aims to reduce the cost by depending on small solenoids. They are more direct, affordable alternatives and have a lower complexity in terms of circuitry compared to piezoelectric devices. With reduced size of a single Braille character, RBD based on single Braille cell is believed to have higher user comfort compared to RBD based on multiple Braille displays. The user’s finger can stay stationary on top of the Braille pins of the single Braille cell and can directly sense the elevations of pins over a period of time, without any additional hand motions required. The design also facilitates portability by reducing the line of Braille display into a single cell, significantly reducing product volume.

CHU, Stephen C-L(@scchuab)
January 19, 2022 3:43 pm
Reply to  YAN, Kai Hang

As we are implementing a single-cell refreshable system, the amount of components needed in the cell is reduced, and also we can use cheaper options in the circuit design. With these improvements made, our product’s price drops to roughly USD$100.

CAO, Xuanyu(@eexcao)
January 19, 2022 2:46 pm

What’s the main challenge of implementing this digital Braille character?

CHAN, Cheuk Yu(@cychancq)
January 19, 2022 2:54 pm
Reply to  CAO, Xuanyu

One of the main challenges is enabling the portability of the digital Braille cell. As stated in the poster, we implemented the Braille circuit with 8 solenoids. Each solenoid would require 1.1A for operating at DC 5V, which would cause the whole circuit to require a high power. It would be quite demanding for the battery supply and challenging to maintain battery level for running hours. We sourced if lithium battery could be a battery choice for battery supply to our circuit. The 3.7V lithium battery alternative would provide enough power but there is slight problem of heat overloading. The heat overloading problem can be further solved by using parallel power supply, i.e. one power supply for 4 solenoids, so we would need a total of 2 of these battery components.

LEUNG, Tiffany Wing On(@twoleung)
January 19, 2022 3:25 pm
Reply to  CAO, Xuanyu

We also faced difficulties in fixing the position of the solenoids. As the solenoids could only function properly when the position of the solenoid bodies are entirely fixed (both vertically and horizontally). However, the 3D printers do not support a just-fit housing for the solenoids as there are errors. We then 3D printed some thin partitions of 1mm to 1.5mm to fill up the space. As mentioned by Joey, we are facing a slight heat overloading problem, adding more partitions could affect the heat dissipation of solenoids. This problem can be solved by drilling holes on the partitions.