Spiderwheels: motion...

Here is a video of a proof of concept I put together.


movement experiment of spider leg... from gavilan on Vimeo.


The materials are minimalistic and only for this experiment. You can clearly see that the leg is cycling through (D = 2, H = 3), then (D = 8, H = 3), then (D = 8, H = 4), then (D = 2, H = 4), then back. With two legs mounted on the front of my robot, this would be enough to propel it forward 6 inches per touch down.

Here is the source code:

#define servo2Pin 2
#define servo3Pin 3

int i;

void setup(){
  pinMode(servo2Pin, OUTPUT);
  pinMode(servo3Pin, OUTPUT);

  Serial.begin(9600);
}

float l1 = 4.5;
float l2 = 6;
float d,H;
void loop(){
  H = 3;
  for(d=2;d<8;d=d+0.2){
    for(i=0;i<1;i++){
      goToAngle(servo3Pin, hipAngle(d, H, l1, l2));
      goToAngle(servo2Pin, kneeAngle(d, H, l1, l2));
      delay(20);
    }
  }
  H = 4;
  for(d=8;d>2;d=d-0.2){
    for(i=0;i<1;i++){
      goToAngle(servo3Pin, hipAngle(d, H, l1, l2));
      goToAngle(servo2Pin, kneeAngle(d, H, l1, l2));
      delay(20);
    }
  }
}

int kneeAngle(float d, float H, float l1, float l2){
  return ((acos((l1*l1 + l2*l2 - d*d - H*H)/(2*l1*l2))*180)/PI);
}

int hipAngle(float d, float H, float l1, int l2){
  return 180 - (atan(d/H) + acos((l1*l1 - l2*l2 + d*d + H*H)/(2*l1*sqrt(d*d + H*H))))*180/PI;
}

void goToAngle(int pinNumber, int angle){
  if(angle <= 180 && angle >= 0){
    sendPulse(pinNumber, (600+(angle*9.72)));
  }
}

void sendPulse(int pinNumber, int pulseWidth){
  digitalWrite(pinNumber, HIGH);
  delayMicroseconds(pulseWidth);
  digitalWrite(pinNumber, LOW);
}

Fun stuff! 50 or so lines can do quite a bit!