Create and Control a Popsicle Stick Finger Robot
Students work through the engineering design process as they are introduced to servos and the flex sensor. They create simple, one-jointed, finger robots controlled by Arduino. Servos are motors with feedback and are extensively used in industrial and consumer applications—from large industrial car-manufacturing robots that use servos to hold heavy metal and precisely weld components together, to prosthetic hands that rely on servos to provide fine motor control. Students use Arduino microcontrollers and flex sensors to read finger flexes, which they process to send angle information to the servos. Students create working circuits; use the constrain, map and smoothing commands; learn what is meant by library and abstraction in a coding context; and may even combine team finger designs to create a complete prosthetic hand of bendable fingers.
A 3D-printed finger for a prosthetic hand.
Flex sensor and servo circuit materials:
- computer, Windows or Mac
- Arduino software; download from https://www.arduino.cc/en/software
- SparkFun RedBoard or Arduino Uno microcontroller and programming cable; an Arduino Inventor’s Kit is recommended (some of its many components are the items listed below), such from SparkFun
- breadboards
- 10k-ohm resistors
- 180-degree servos; one comes with the Arduino Inventor’s Kit recommended above—the generic sub-micro size servo from SparkFun, or obtain higher-quality servos such as the Hitec HS-422 standard size from SparkFun
- flex sensors; one comes with the Inventor’s Kit above—a 2.2-inch flex sensor from SparkFun
- soldering iron, to prepare the flex sensors; see note below
- solid core wire
- shrink-wrap
Note: The flex sensor pins are not ideal for use with breadboards. So, in preparation for this activity, it is recommended that you solder two solid core wire leads that are at least 6-inches long onto the flex sensor. After soldering the solid core wire, apply shrink-wrap to the leads to protect the flex sensor during the activity.
A flex sensor (with additional wires) taped onto a finger.Copyright 2017 Dan Godrick, ITL Program, College of Engineering and Applied Science, University of Colorado Boulder
Finger materials:
- Popsicle sticks
- string
- elastic bands
- glue
- tape, to affix the flex sensor to the hand; encourage students to experiment with other methods—gloves, athletic wrap and stretch fit materials (such as these cool finger sleeves from JBM) work well!
Contributors
Daniel Godrick
Supporting Program
ITL Program, College of Engineering and Applied Science, University of Colorado Boulder
Acknowledgements
This activity was developed by the Integrated Teaching and Learning Program in the College of Engineering and Applied Science at the University of Colorado Boulder. Special thanks to Jacob Segil and SparkFun Education.
Copyright
2017 by Regents of the University of Colorado