In the Fall of 2017, a group of three classmates and I were given a Senior Design project involving circuitry, coding, and 3-D printing. To start, we were tasked with finding or making a way to access and track the hand and finger data collected from a Leap Motion controller. Then, using that information, we were tasked with determining a way to move a 3-D printed hand of our own design by a proportional amount. In effect, our 3-D printed hand should be able to mimic a user's movements which have been captured by a Leap Motion controller.

 

As a way to begin determining these proportional amounts, I set about creating a robotic hand of my own.

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To begin creating my robotic hand, I first researched the various kits and designs available online. I also made special note of their control techniques, which included servos run by micro-controllers, manual actuation, and even voice commands. In the end, I decided on creating a robotic hand that would be run with an Arduino micro-controller. This micro-controller would process input from flex sensors and output proportional angle values to servos. Although I purchased a kit to procure all the requisite hardware, I chose to create the robotic hand myself.

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During the execution of this project, I practiced the various skills I developed during my Prototyping class: circuit-building, soldering, and trouble-shooting. I also relied heavily on my time-management and research skills in order to use my time effectively as well as efficiently research my technical problems. Throughout this experience, I honed the skills necessary to make myself a competent problem-solver and project builder. If I learned anything from this experience, it's that good problem-solving requires using your collected knowledge and experiences to ask the right design questions.

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By the end of this experience, I created a robotic hand with circuitry and Arduino code I hand-crafted. My robotic hand responds well to even the smallest movements of a user's hand, and it also provides a successful proof of concept for further use in my Senior Design project.

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Below are pictures of my robotic hand project. The image on the left is of my control glove, which has flex sensors sewn along the top of each finger. These flex sensors, when bent, offer different levels of resistances. When a voltage is run through them and the 10k-ohm resistors soldered onto a breadboard at the wrist, this creates variable voltages which can be used as input values. Note the five leads of various colors coming out of the middle of the circuit. These are the signal leads, which provide input for the Arduino via its A0 through A4 pins.

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The image on the bottom left is a close-up of my robotic hand. Note the servos, which are connected to each finger-tip by fishing line tendons. Also note the divots cut into each electrical tubing finger, which represent finger joints and allow for more accurate anthropomorphic movement.

 

The image on the right is of my completed project. It includes my robotic hand, my control glove, and a rechargeable battery I use to power my servos. After values are fed to the Arduino through its analog pins, the Arduino takes these values and constrains them to a range of 0 to 180. These represent angle values, and they provide a proportional range of movement given the limits of the servos. This modified signal is then fed to the servos through the Arduino's pulse width modulation digital pins. The servos turn through an angle proportional to its finger's input value, which pull on fishing line tendons connected to the tip of each electrical tubing finger. 

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Also below is a button to download a word document of my Arduino code. Furthermore, if you have any more questions about my design process, feel free to contact me.