Assignment: Sensing PART II: Force Sensitive Resistors and Photocells
Collaborators:
Assignment: Sensing PART II: Force Sensitive Resistors and Photocells
Collaborators:
Description:
For the second part of this assignment, I used the force sensor to augment a rock climbing shoe. In climbing it is good technique to use the small area underneath the big toe to stand on, generally, and so the force sensor was about the right size to fit in that space but not so big that it would give false readings when other parts of the foot were used, (when the wearer gets sloppy.) The sensor and soldered connection were padded with cotton, wrapped in saran wrap and then in athletic tape. The flat assembly was positioned inside the shoe, and then the shoe put on. The blue, green and red led's would light up depending on how much pressure was being applied. At maximum pressure, all three would be lit, at only a little pressure, only the blue, etc. If the overall package (LEDs, board, etc.) was more independent, this could be used as a teaching tool, for example, giving the instructor in a gym visual feedback on the climber's footwork.
Materials:
Force Sensor
Resistors/Wires/Arduino
LEDs
Saran Wrap
Cotton
Athletic Tape
Code:
This was repurposed from the previous assignment with the potetiometers...
/*
*
* Control 3 LEDs with 1 force sensor
*/
// Analog pin settings
int aIn = 0; // Potentiometers connected to analog pins 0,
// int bIn = 3; (Connect power to 5V and ground to analog ground)
// int cIn = 4;
// Digital pin settings
int aOut = 13; // LEDs connected to digital pins 9, 10 and 11
int bOut = 12; // (Connect cathodes to digital ground)
int cOut = 11;
// Values
int aVal = 0; // Variables to store the input from the potentiometers
int bVal = 0;
int cVal = 0;
// Variables for comparing values between loops
int i = 0; // Loop counter
int wait = (1000); // Delay between most recent pot adjustment and output
int checkSum = 0; // Aggregate pot values
int prevCheckSum = 0;
int sens = 3; // Sensitivity theshold, to prevent small changes in
// pot values from triggering false reporting
// FLAGS
int PRINT = 1; // Set to 1 to output values
int DEBUG = 1; // Set to 1 to turn on debugging output
void setup()
{pinMode(aOut, OUTPUT); // sets the digital pins as output
pinMode(bOut, OUTPUT);
pinMode(cOut, OUTPUT);
Serial.begin(9600); // Open serial communication for reporting
}
void loop()
{i += 1; // Count loop
aVal = analogRead(aIn) / 4; // read input pins, convert to 0-255 scale
bVal = analogRead(bIn) / 4;
cVal = analogRead(cIn) / 4;
analogWrite(aOut, aVal); // Send new values to LEDs
analogWrite(bOut, bVal);
analogWrite(cOut, cVal);
if (i % wait == 0) // If enough time has passed...
{ checkSum = aVal+bVal+cVal; // ...add up the 3 values.
if ( abs(checkSum - prevCheckSum) > sens ) // If old and new values differ
// above sensitivity threshold
{if (PRINT) // ...and if the PRINT flag is set...
{ Serial.print("A: "); // ...then print the values.Serial.print(aVal);
Serial.print("\t"); Serial.print("B: "); Serial.print(bVal);
Serial.print("\t"); Serial.print("C: "); Serial.println(cVal);
PRINT = 0;
}
}
else
{PRINT = 1; // Re-set the flag
}
prevCheckSum = checkSum; // Update the values
if (DEBUG) // If we want debugging output as well...
{Serial.print(checkSum);
Serial.print("<=>");Serial.print(prevCheckSum);
Serial.print("\tPrint: ");Serial.println(PRINT);
}
}
}
