Part 3 has an identical flow of data to part 2, the only difference is the type of sensor and the 3-dimensional relationships it effects. In this example we use a PING))) Ultrasonic Sensor to measure the proximity of an object (in this case my hand) to the sensor.  The ultrasonic range finder works by sending out a burst of ultrasound and listening for the echo as it reflects off an object. Code written to the Arduino board sends a short pulse to trigger the detection, then listens for a pulse on the same pin using the pulseIn() function. The duration of this second pulse is equal to the time taken by the ultrasound to travel to the object and back to the sensor. Using the speed of sound, this time can be converted to distance. For more information on the code and circuit click here.

The code written by Arduino prints values in “in” and “cm”. In this example we only need one value so we will use Serial.println(cm) and comment out the other Serial.print() functions. This will send a single array of values through the serial port similar to the example in our previous post. In Rhino the aperture is built by crating a circular array of pivot points about a center axis. These pivot points rotate a series of overlapping blades controlled by a singe parameter.

The values streaming from the serial port are fed directly into the grasshopper build driving the rotation of blades. To see this process in action see the video below. Notice the values printed to the ‘right’ screen displaying the distance in centimeters.

See the video in HD here.

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