Mechanical Design
Reliefeelable has a complex mechanical design intended to balance various aspects such as; cost, speed, form factor, resolution.
In the sections below we describe basic idea and then go more in depth about the mechanical design of Reliefeelable
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Linear Actuator
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Actuator brackets
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Pin display
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Gantry
Basic Idea of Relifeelable's Mechanical Design
We have a gantry at the bottom which moves the motors row by row. Then sitting on top of the gantry there are the linear actuators, they lift the pins. Next we have the foam. We are using the foam to hold the pins in place, after the linear actuator lifts the pin, the foam stops it from falling back down. Last of all we have the pins which is what the blind person actually feels.
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Linear Actuator
We had the following requirements for our linear actuator.
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Small form factor, so the pins could be close by.
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Lower power consumption so we can run the actuator using small
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Cheap, because there are many linear actuators on the display
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On the right is the image of the 6 different types of linear
actuators we tried to use.
A is the linear actuator we chose. We made this linear actuator ourselves. We used a DC motor, an axle spacer, and a 3d printed straw. The DC motor moves the spacer, which is the pin for our display. We need the straw around the spacer to make the spacer move up and down instead of just turning in circles. The straw is like a hand holding the spacer and when you hold the spacer it moves up and down because it can't turn.
A B C D E F
Gantry
One of the main problems was the price. Our original plan was to have one linear actuator per pin but, there would lots of pins and the price would be way to much. So, we came up with these 3 options
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One motor per pin, our original plan
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A gantry to move a row of motors
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One motor to lift the pins, one gantry to move in the x axis and one gantry moving in the y axis
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When choosing an option we had to balance the price with the time it would take to show a painting on the tactile display. We chose the option using a one dimensional gantry motors with a row of motors on it. The gantry moves to each row of pins and the motors would lift the pins.
Pin Display
Our pin display consists of a foam and 3d printed pins. At first we thought we could just have pins at the top but, then we realized that after the gantry moves to the next row of pins, the first row of pins will fall down. After a lot of research we found out about a device called the pin screen. The pin screen was a way to create movies in the 1935's. It was made of many pins which would cast shadows, making an animation. The pins were held in place by a piece of foam.
We implemented this same technique in our pin display by using foam to hold our pins. We had to first decide which type of foam we should use. After a lot of research we decided on using a EVA foam sheet.
