A demonstration of a pointing gesture being mirrored
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3D-Printed Robotic Arm
3D-Printed Robotic Arm
Summer 2018
PURPOSE
To independently develop a humanoid arm capable of mirroring movements detected through a glove.
Terminology & Definitions
Terminology & Definitions
XBee - Digi XBee. A family of wireless connectivity modules from Digi International.
PCB - Printed Circuit Board.
Serial monitor - An on-screen display that shows code outputs.
HOW DOES IT WORK?
In short, the user wears a glove equipped with flex sensors. When the user bends their fingers, the corresponding fingers of the robotic hand also bend.
Flex Sensors
The sensors in the glove are flex sensors. These are secured to the glove and are soldered to a PCB, which also houses 25 other components. Wires connected to the PCB supply power to the flex sensors using the Arduino board, and read the values given by them. The flex sensors act as variable resistors that change in value according to how much they are bent.
Arduino
The Arduino board reads these drops in voltage and uses my code to translate them into a certain number of degrees (from 0 to 180). This number is sent to servos installed in the robot, and to Arduino's serial monitor, which essentially gives an inside look of the values as they are being translated.
Servos
Each servo has three wires: power, ground, and control. Power and ground are connected to an external battery in order to power the servos. The servos take in the number of degrees given by the Arduino board through their control wires. As they turn, they pull nylon fishing lines that are attached to their arms. These fishing lines are used to bend and straighten the robot's fingers.
The very basic wiring of the project.
CHALLENGES
Implementing a 5th motor system for independent pinky movement.
Complete and accurate movements in all fingers using nylon strings.
SOLUTIONS
Used power tools to adjust servo arm lengths and added new pathways for additional circuitry.
Trial and error!
If I were to return to this project with the skills that I currently possess, I would edit the provided CAD file to allow for more realistic movements in the base of the thumb.
I would also use an XBee module to make the connection between the robot and the glove wireless.
In addition, a cover to conceal the inner workings of the arm would make for a much more presentable final product.
A close up of the servos within the hand.
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