Sketches for interfacing Robotic Materials' FA-I tactile sensor, sensing arrays and multi-finger configurations.
- force_proximity_eval Sketch for reading a single sensor (evaluation kit)
- force_proximity_fingers Sketch for reading multiple sensors via dedicated I2C channels (e.g. Kinova fingers)
- force_proximity_multi Sketch for reading sensor arrays (e.g. Rethink Robotics grippers)
You will need a copy of the Arduino IDE and any compatible Arduino device that supports I2C, 3.3V and 5V. If you have ordered a kit from Robotic Materials Inc. that includes a Teensy LC or Teensy 3.5, you will need to install Teensyduino from https://www.pjrc.com/teensy/teensyduino.html.
Connect the Arduino/Teensy to your serial port and launch the serial plotter from the Arduino IDE. You should see something like this:
The blue signal is the raw proximity/force reading. After touch, it roughly corresponds to the human SA-I signal, that is slow adapting pressure. You would not notice anything if it slowly changes, but only if the value exceeds a certain threshold. The yellow signal roughly corresponds to the human FA-I signal, that is fast adapting pressure. It helps you notice changes such as the lightest contact, but keeps quiet for constant pressure. Thinking about wearing clothes is a good analogy: your FA-I sensors alert you when you wear them and your SA-I sensors ignore them, but notice of you larger changes. The third signal is the result of a touch detector that analyses the FA-I signal and its derivative. The picture shows two touch and release events that correspond to minima and maxima in the FA-I signal, respectively. These minima and maxima can be detected in the code, which outputs a "T" for a touch signal and a "R" for a release event.
Switch to "Serial Monitor Mode". You will see three comma-separated values like those
38859,-29261,0
40856,-22480,T
41211,-16091,0
41479,-11532,0
41454,-8048,0
41195,-5375,0
39526,-2094,0
23951,14109,0
12157,21670,0
9185,18141,R
8438,13445,0
8213,9636,0
8121,6837,0
8081,4825,0
8037,3421,0
The first value is the raw sensor reading that corresponds to proximity or force before or after contact, respectively. The second value is the FA-II value, and the third column indicates a detected touch ("T") or release ("R") event. You will see three columns per sensor.
You can enter the following commands into the serial terminal:
h: A list of possible commands
c: Toggle continuous mode
s: Single-shot measurement
t: Toggle touch/release analysis