Steve Lu's Documentation Blog

Recitation 3: Workout

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Bicep curls

Challange: Tricep curls

 

Code

int SENSOR_PIN = 2;
int tiltVal;
int prevTiltVal;
int count = 0;
int set = 0;
void setup() {
  pinMode(SENSOR_PIN, INPUT); // Set sensor pin as an INPUT pin
  Serial.begin(9600);
  Serial.println(“hey weak man, start your workout now!!!!!!”);
}
void loop() {
  // read the state of the sensor
  tiltVal = digitalRead(SENSOR_PIN);
  // if the tilt sensor value changed, print the new value
  if (prevTiltVal ==0 & tiltVal ==1) {
    count +=1;
    Serial.println( );
    Serial.println(count);
  }\
  if (tiltVal != prevTiltVal) {
    //Serial.println(tiltVal);
    prevTiltVal = tiltVal;
  }
  if (tiltVal != prevTiltVal) {
    //Serial.println(tiltVal);
    prevTiltVal = tiltVal;
  }
  if (count == 8) {
    Serial.println(“Yay, you ve done one set of curls”);
    count = 0;
    set += 1;
    Serial.println(“live on keeping on, do another set”);
    Serial.println(“set number”);
    Serial.print(set);
  }
  delay(10);
}

Showcase

Reflection

  • At what angle of tilt does it transition between HIGH and LOW?

The mercury switch transits between HIGH and LOW when it’s tilted slightly around horizontal angle. Whether above or below the horizontal line would turn it on depends on which ends of the switch is placed on top.

  • What else did you notice about its behavior?

Mercury switchs are directional, which means that if we turn it the other way around or put it at level, it gives inversed value or may not function properly.

  • What if you rotate the limb that has the sensor attached to it?

With all due respect, this question is kinda ambiguious. Since human limbs provide high degree of freedom, the answer depends on what kind of rotation we perform.

  1. If we rotate our limb around the axis along our limb, nothing will happen.
  2. If we rotate our limb around the verticle axis, nothing happens as well.
  3. If we rotate our limb up and down around the center of our shoulder, it will resemble the tilt up and down motion of forearm.

  • What if you shake it?

The number alters between 0 and 1. I am afraid that I don’t get the point of trying to make sense of the switch through observation. Why don’t we take first-principle thinking, namely to understand the mechanism inside. It’s a simple mercury switch. Two abreast pins installed in a glass tube and a drop of mercury, there’s nothing more than that. When the drop immerses the pins, current passes through; when there’s no immersion, the switch is off. So, as we shake it, the drop is flying around the tube, which randomly connects and breaks the circuit.

  • What if you hold the wires several centimeters away and tilt it?

This doesn’t make any difference, but it seems that not until we move the switch a bit further the switch remains open, which is rather intuitive. A longer lever arm requires a greater displacement to work.

  • Do you think it can be used by any user?

玩RPG也能鍛鍊身體！任天堂新作《健身環大冒險》搭配「Ring-Con」正式發表

The workout machine is still quite primitive. Since the coding part and the position of the device have to be synchronized, it is not a ready-to-use device. We should first do some delicate packaging, and clearly label the direction of the switch. Also, I believe it would be better if we can get rid of the wires and turn to bluetooth instead so that it’s much neater and easier for users to workout.

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