4. FSR on Soccer Ball with Bouncy Mushroom Visualization
Mushroom Visualization with FSR on Soccer Ball
Attaching a force sensitive resistor to a soccer ball, a graphical visualization of a mushroom responds to the force on the ball.
Movie: http://www.youtube.com/watch?v=x70qSX6HOkc
Processing Code: (based on spring example)
/**
* Mushroom
*
* Squeeze force sensor start the spring.
*/
// Spring drawing constants for top bar
int s_height = 80; // Height
int left = 50; // Left position
int right = 250; // Right position
int max = 450; // Maximum Y value
int min = 50; // Minimum Y value
boolean over = true; // If mouse over
boolean move = false; // If mouse down and over
// Spring simulation constants
float M = 1.9; // Mass
float K = 0.1; // Spring constant
float D = .97; // Damping
float R = 100; // Rest position
// Spring simulation variables
float ps = 200.0; // Position
float vs = 0.0; // Velocity
float as = 0; // Acceleration
float f = 0; // Force
float FSR = 0; // Force Sensor Position
import processing.serial.*;
// Change this to the portname your Arduino board
String portname = "COM6";
Serial port;
String buf="";
int cr = 13; // ASCII return == 13
int lf = 10; // ASCII linefeed == 10
void setup()
{
size(300, 500);
rectMode(CORNERS);
smooth();
port = new Serial(this, portname, 9600);
frameRate(60);
}
void draw()
{
background(100, 150, 0);
updateSpring();
drawSpring();
}
void drawSpring()
{
// Draw base
fill(255);
float b_width = 0.25 * ps;
if (b_width > 75){ b_width=75;
} else if (b_width < 15){ b_width=15;}
rect(width/2 - b_width, ps + s_height, width/2 + b_width, 700);
// Set color and draw top arc
if(over || move){
fill(255,0,0);
} else {
fill(204,0,0);
}
arc(left/2+right/2,ps+s_height,right,(max-ps)/4+s_height,PI,TWO_PI);
//rect(left, ps, right, ps + s_height);
}
void updateSpring()
{
// Update the spring position
if(!move) {
f = -K * (ps - R); // f=-ky
as = f / M; // Set the acceleration, f=ma == a=f/m
vs = D * (vs + as); // Set the velocity
ps = ps + vs; // Updated position
}
if(abs(vs) < 0.1) {
vs = 0.0;
}
// Set and constrain the position of top bar
if(move) {
ps = FSR - s_height/2;
if (ps < min) { ps = min; }
if (ps > max) { ps = max; }
}
}
// called whenever serial data arrives
void serialEvent(Serial p) {
int c = port.read();
if (c != lf && c != cr) {
buf += char(c);
}
if (c == lf) {
int val = int(buf);
println("val="+val);
if (val > 800){
move=true; over=true;
FSR = map(val,800,1024,0,400);
}else if (val < 800){
move=false; over=false; FSR=0;
}
print("FSR="+FSR+" ");
buf = "";
}
}
