University of Pennsylvania
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Senior Design: MEAM 445/446
Knowledge.Dots
Braille Education Tool
Overview
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Knowledge.Dots was created as the capstone project in the mechanical engineering department at the University of Pennsylvania. The Knowledge.Dots team consisted of 5 mechanical engineering seniors; myself, Julia Hegarty, James Lovey, Joseph McCloskey, and David Shields. The goal of this project was to bring the freedom and power of modern technology to those just learning braille in an affordable and accessible fashion. Over the course of the 2015-16 school year, our team explored solutions to the problem of a lack of educational tools available to the visually impaired. This project was created under the guidance of mentors such as Suzanne Erb (a blind literacy activist in Philadelphia), Frank Irzyk (Technology Coordinator at Overbrook School for the Blind), and Dr. Kevin Turner (Professor of Mechanical Engineering). In the end, a proof-of-concept prototype was created at a much lower price point than current products on the market. This page will provide an overview of the project. The full write up, along with files associated with the project, can be downloaded at the bottom of the page.
The Knowledge.Dots team on Design Day in front of the project and the poster. Pictured from left to right: James Lovey, Joe McCloskey, David Shields, Brennan Spinnie, Julia Hegarty, and advisor Suzanne Erb.
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According to the National Federation of the Blind, 90% of blind children are not being taught braille. This is astonishing considering many studies have linked braille literacy to higher employment rates and greater independence among the blind. The Knowledge.Dots team believes that a large part of the problem is access to braille educators and education materials at an early age. To solve the problem of lack of educational materials for the blind, my team sought to create a low-cost, refreshable braille output device that could be connected to a computer. Our focus was on the actuation method that would act as a platform that software could be built off of. Through research and design iterations, an electro-mechanical approach was taken as a lower cost alternative to current piezoelectric braille output devices. In the end, we decided on a method that we dubbed "The Sliding Method." This method greatly reduced the number of actuators from one actuator per braille dot (48 for an eight character display) to four for the entire system.
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The Sliding Method
One of the largest problems to solve on this project was creating a mechanical actuation method while maintaining the small size of braille according to the United States Braille Standard. The sliding method was decided as a result of these considerations. As mentioned before, this method reduces the actuators to 4 for the entire system, no matter how many characters are being displayed. A braille character consists of an array of dots, 3 dots high by 2 dots wide. The sliding method actuates these dots through the use of 3 solenoids. These solenoids slide under a column of 3 dots in a character. If a dot needs to be raised, the respective solenoid is actuated. It pushes the dot into the upper housing and a sled slides underneath, locking the the dots in either the up or down position. The activated solenoids then fall and a motor drives them under the next column of dots. This process can be repeated over an indefinite amount of characters.
A large consideration in the actuation method was the latching mechanism. When holding the dots in place, individual latches tend to be very unreliable due to the small size of the dots and the number of latches needed. Therefore, we decided on a large, universal latch. This was embodied in the form of the sled. The sled is large, reliable, and only requires one piece, therefore it solved the problem of unreliable mechanical latching. |
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Pin Pusher System
In the sliding method, the pins do not directly interface with the rods of the solenoids. Instead, a pin pusher system is used to meet size and space constraints. Due to the size of the solenoids, it is advantageous to align the solenoids horizontally. However, this requires a linkage system to translate horizontal motion to vertical motion. The Scott-Russell mechanism (pictured to the left) was decided on as the best translation method.
The Scott-Russell mechanism also contains a mechanical advantage that was necessary in this system. If the system is started at the proper angle and the length of the linkage arms are increased to be longer than the throw of the solenoid, the vertical portion of the throw can be longer than the horizontal portion of the throw. This magnification was very useful in our system as the solenoids had a throw of about 4.5 mm, which we were able to increase to the 11 mm needed to fully activate the pins. The graph to the left shows this amplification due to start angle. Below is pictured the final Scott-Russell linkage in the pin pusher assembly. |
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Conclusion
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In the end, we were able to prove the concept of a low cost, electro-mechanical braille output device. The final prototype, due to timing issues, was not working reliably on design day. However, both the actuation and latching mechanism were proven to have worked. With a few small tweaks and a couple more prototyping iterations, this design could be working reliably and continuously. The final prototype has an estimated final cost of $173.51, including materials, manufacturing, and other considerations. Therefore, this deice would sell at about one tenth of the cost of current devices on the market. This order of magnitude difference could make electronic resources much more accessible for people learning braille. Knowledge.Dots can be used to bring educational resources to the blind, which in turn will allow for greater freedom and independence.
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My Role
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During the course of this project, I was heavily involved in manufacturing. I worked on design, specifically design for manufacturability, making sure that the systems we were creating could be made with the manufacturing capabilities available to us. I was also directly responsible for designing, prototyping, and testing the drive system that would propel our pin pusher assembly. I ensured that the system was accurate and reliable enough to hit the small tolerances that braille requires. For the final prototype, I manufactured many of the parts through machining, laser cutting, and 3-d printing. I was heavily involved in assembly, testing, and timing of the final prototype. At times, my duties also overlapped with electronics and coding of the system.
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Documentation
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| solidworks_drawings.zip |
Mechatronics: MEAM 410/510
Robockey
Ace, Spade, and Jack
Robockey is one of the biggest challenges I have faced in my academic career. We worked for five weeks in a team consisting of Joe McCloskey, Julia Hegarty, James Lovey, and I to create a team of 3 autonomous, hockey-playing robots (Ace, Spade, and Jack). All of this work accumulated into an annual Robockey tournament made up of 24 teams. Our team tied for ninth in this tournament after making it to the main event. We were proud of this result as a team of four Junior mechanical engineers surrounded by teams of mostly grad students that included a computer science or electrical engineering student.
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Parameters
Input Controls
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This is the highlight video put together by James Lovey from the Robockey tournament.It shows our struggles at the beginnings followed by the break through and victories. Click here if you would like to see the full matches from team 4!
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The Details
This project combines mechanical, electrical, computer, and systems engineering all in one. Even though the robots may look similar across the teams, each robot contains hand-soldered circuit boards, unique mechanical designs, and code written from scratch. The center of each robot is an M2 microcontroller. This attached to peripherals such as the m_rf (wireless module) and m_wii (blob tracker). The m_Wii uses a Wii remote camera which outputs the four brightest infrared spots it sees and their location in the image in pixels. From this output, we are able to locate the robots on the rink as the constellation of infrared LED's is fixed in a specific location above the rink. Each robot also contains nine infrared photo-transistors around their perimeter. These are used to detect the puck through analog inputs on the microcontroller. Our robots were designed to be compact and fast. The electronics were packed as low to the ground as possible. Pennies were incorporated into the base to hold the quick robots on the ground and apply more power in face off situations. Ace, Spade, and Jack were lighter and smaller than most teams that we faced, but they served their purpose and often reached the puck first. |
Challenges and Solutions
Mechanical Design
Mechanical Design
- The motors, sitting axially, did not leave enough room for the wheels to be protected and the robots to stay within a regulation diameter. We solved this by 3-D printing thin shields to fit just around the wheels. These can be seen on the pictures of Spade above.
- The robots were too light. They often lost traction and were "getting rocked." To fix this, an extra layer was added to the base which was designed to hold pennies.
- We had very powerful motors on our robots. These exceeded the current capacity of the motor drivers that were being used. In the end, we stacked the motor drivers and lowered the pulse width modulation on the drivers to reduce the overall load.
- Broken solders and shorts were a huge issue. One of the robots did not work due to a short and broken solders caused many troubles. These were solved with lots of testing with a multimeter.
- Tracking the position of the robot took a lot of time. Issues arose with signs, syntax, and putting data in the right place when running it through the complicated math that analyzed the data from the m_Wii. A large chunk of time was spent debugging this part of the code through USB outputs until we achieved the results we were looking for.
- Controlling the robot to drive to a spot smoothly was another huge challenge. Multiple tests were run changing the variables in the control part of the code until we achieved the results that we were looking for.
- Lastly, endless bugs plagued our code, just like any normal computer science project. Whether it was a semi-colon, capitol letter, or some other error, we spent hours combing through the code to find where the issue was at.
Conclusion
In the end, this project was a huge learning experience in computer science, electrical engineering, mechanical engineering, and how all of those systems work together. It was also great for understanding better how to work in a team. The headaches, sleepless nights, and horrible diet were well worth the end result and I was so thankful to complete this project with some of my best friends, Joe McCloskey, James Lovey, and Julia Hegarty. Also, a huge shout out goes to coach Sean Reidy for his guidance and inspiring speech before the final tournament.
In the end, this project was a huge learning experience in computer science, electrical engineering, mechanical engineering, and how all of those systems work together. It was also great for understanding better how to work in a team. The headaches, sleepless nights, and horrible diet were well worth the end result and I was so thankful to complete this project with some of my best friends, Joe McCloskey, James Lovey, and Julia Hegarty. Also, a huge shout out goes to coach Sean Reidy for his guidance and inspiring speech before the final tournament.
Labyrinth
Jerry
This project was designed to run a maze when given inputs from a controller attached by a ribbon cable (the controller is already designed and assembled). Given two 50:1 motors, this device was required to carry a 500 gram mass as well, while running the maze. This was held in place by the holes in the top and middle plates. In order to fit on the maze, the robot was required to fit in a 15 cm diameter. However, I designed this device to fit well within this range (about 10 cm at its widest point) in order to allow for maximum maneuverability. It carried the 500 grams with ease and was able to navigate the maze in 39 seconds. The main issue with the design were that the controls were slightly too touchy, making it difficult to turn the right amount. The compact design and the high speeds that the device was able to achieve were positive takeaways from this project.
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Orchestra
Too Hot to Handel
Too Hot to Handel is meant to receive wireless signals and play the given frequency for the given duration. This project was powered by the M2 that also powered the Robockey robots. The biggest challenge faced in this project was not the wireless signals but rather creating a sine wave. A microcontroller can only output high or low voltages. To turn this into a sine wave, a varying pulse width modulation was used and the signal was then passed through electronic filters in order to create a signal at the desired frequency. This signal then powered the speaker. Above is a rendering of the device and below is an example of the code and the circuit diagram.
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Design and Manufacturing: MEAM 201
Stirling Engine
Turntable
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The Stirling Engine is a project put together over a semester of learning manufacturing techniques. It mainly focused on milling and lathing, using both hand-controlled and CNC machines. The base was cut by a water jet from an outside source. Each part was manufactured to within five thousandths of an inch to the specified dimensions. Eight of the parts were given as engineering drawings, already designed. The other eight were designed by me to fit the correct specifications of the already existing parts. This gave insight not only into how to use manufacturing techniques, but how to design parts with specific techniques in mind. This project provided crucial hands on experience and insight into the industries in which I am interested.
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In the final test, my engine ran very smoothly at 800 RPM. This specific model is a gamma type Stirling Engine. Stirling Engines run by moving air between hot and cold sections, pulling the piston in as the air cools and pushing it out as it heats. The displacer, which moves the air, is driven by the piston and is offset at 90 degrees. It moves back and forth between the section exposed to the flame and the ridged section called the heat sink. The heat sink has a large surface area and therefore dissipates heat into the atmosphere very quickly. This is how the heat differential needed to drive the motor is created. The counterweight (made out of brass) and the flywheel (the record) provide enough momentum and weight for the motor to continue turning even when the piston is not engaged in the power stroke.
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Product Design: MEAM/OPIM 415
Cupple
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Over the course of a semester, this class of 60 students learned the process of product design through application. An initial 1000 ideas, generated by the students, were whittled down to twelve, culminating in a design fair where other students voted on the ones they would be most likely to buy. My team, Cupple, created a detachable, mobile cup holder that "couples" with tables through a spring loaded clamping mechanism. In the end, the product fared decently, commanding eight percent of the market share. This class taught how to go about the design process, identifying customer needs, manufacturing a product, and bringing the product to market.
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The Cupple team. Left to right: Chloe le Comte, Mike Meigs, Brennan Spinnie, Xinqian Xiang, Ezgi Aytac
Mechanical Design: MEAM 101
Locomote
The Tortoise
This project specifically focuses on the mechanical design aspect of a system. Given a simple DC motor circuit powered by a super capacitor, the goal was to create a device to travel as far as possible on a single charge. The catch is the device could not use wheels or roll, it had to use another method to move. We decided to go with a pull-and-drag design, which somewhat resembles how a tortoise would move. The intent of this design was to put the motor and electrical equipment in the back and attach the rotors to pulleys to create a smaller load for the front to lift. However, this design backfired as the pulleys ended up weighing more than the electrical system. However, it was still a successful project and taught many lessons in teamwork.
Press FitFormula 1
Created completely without glue, Formula 1 emphasized using friction fits as an attachment method. All of the parts were created on a two dimensional laser cutter. The three dimensional geometry is created completely from flat parts being pressed together. No adhesives, fasteners, or any other attachment methods were used. A maximum material limit was also taken into account. I was particularly proud of how the designed turned out and the parts fitting on the first try.
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Puzzle PieceMile High Salute
The Mile High Salute was one of the first CAD and laser cutting projects that I ever completed. It was meant to teach methods of manufacturing on a laser cutter. I added my own personal flair in support of my favorite NFL team.
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