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View demonstration of the CUB

Design Concept of the CUB

The key components in the CUB are;

•  Low friction, lightweight materials

•  Embossing & paper feed mechanism

•  ARM Micro Controller (Linux kernel)

•  24 key keyboard

•  FPGA for Braille translation and keyboard encoding

•  Doubletalk Speech Synthesis

•  LCD Screen

Materials

Weight, maintenance and cost need to be kept to a minimum in a device such as the CUB so as to maintain portability and the low servicing requirements. Two important areas for consideration are the sliding platforms and their rails.

The Embossing Tool is built to take the force of the solenoid whilst still being able to slide along its rails. One of the best plastics available is Polystone Ultra. [5] Polystone Ultra is a low friction, high impact resistant plastic. It has been specially formulated for improved sliding characteristics, resistance to wear, abrasion and environmental stress cracking . The embossing tool platform is shown in Figure 3 .

In order to reduce the weight in the prototype, an alternative to steel rods was found. Pultruded Fiberglass is one quarter the weight of steel, has a tensile stress of 690 MPa [6] compared to a yield strength of 690 MPa for a high strength steel-alloy [ASTM A-514]. [7] Although not as strong as high tensile grade steel, it is still strong enough to suit the CUB requirements, but with a significant weight advantage.

A wear experiment between the Polystone Ultra and the Pultruded fiberglass was conducted. The setup involved only 1 fiberglass rail (instead of two) and a weight well in excess of the components on the platforms (500g). The equivalent of over 10,000 Braille pages could be printed with no visibly detectable or measurable wear.

Pultruded Fiberglass is a uniform composite containing 75 percent glass and a small content of silicon. [6] Should wear occur, it is not expected to see an exponential wear pattern because its of its uniform cross sectional consistency.

Design Concept

Design Concept: Impact Mechanism

Design Concept: Embossing Mechanism

Keyboard

Operation System and Application

Future Development