... | ... | @@ -32,9 +32,14 @@ We began by rebuilding the robot, looking at the illustrations for the building |
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### Vehicle 1
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For the first part of the exercise we wrote a program, **SoundLover.java** [TODO: ref], that made the robot drive with motor power proportional to the sound level measured by a single sound sensor. We could not find specifications on what the sound sensor measures, or what the range of these measurements are, but the readings returned from it appear to be (dB?) values somewhere between 0 and 100. We base this on the fact that the absolute highest value seen in our most extreme experiments in the Lesson 3 exercises (where we also used the sound sensor), was a value of 92. Since the interval appears to be [0, 100], we deemed it reasonable to simply map the read sound value directly to motor power and so we pass the measured sound level returned by *readValue()* along as the value for the motor power parameter. Ideally we would run some more thorough experiments to figure out the exact range that the sound sensor can measure, but we opted not to do this. The result of running this program can be seen in (TODO: INSERT VIDEO)
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For the first part of the exercise we wrote a program, **SoundLover.java** [TODO: ref], that made the robot drive with motor power proportional to the sound level measured by a single sound sensor. We could not find specifications on what the sound sensor measures, or what the range of these measurements are, but from our experiments with the sound sensor in Lesson 3 in which the highest value observed was 92, we infer that the readings returned from the sound sensor appear to be dB values somewhere between 0 and 100. Since the interval appears to be [0, 100], we deemed it reasonable to simply map the read sound value directly to motor power and so we pass the measured sound level returned by *readValue()* along as the value for the motor power parameter.
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[Video goes here]
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A range of 0 to 100 could make sense as it incorporates noise levels up to shouting and loud music [3], excluding aeroplane noise and noise above the pain threshold, which seems reasonable for a robot intended for educational purposes. On the other hand, we may simply not have observed higher values as there were no sound sources present to produce noise of that loudness level. This, however, is not important as we will most likely not encounter sound of that level during this session either. And if we do, our past experiences has shown that when values higher than 100 are passed to the robot's motors, they are simply interpreted as a value of 100.
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Ideally we would run some more thorough experiments to figure out the exact range that the sound sensor can measure, but we opted not to do this. The result of running this program can be seen in [TODO: ref til video].
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[TODO: Video]
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*Video 1: The robot responding to loud noise by driving fast and to lower noises by driving slower*
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As can be seen in the video, the robot starts driving forward fine when measuring a sound, however, it keeps driving full speed forward despite receiving no sound. We judge this being a result of the sound sensor either vibrating too violently when the robot is driving full force, resulting in the sensor interpreting it as a loud sound, and such causing a constant feedback causing it to keep driving forward. Alternatively, simply the sound made by the motor is causing it to keep driving, or possibly a combination of the two.
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... | ... | @@ -119,4 +124,6 @@ The video shows that the robot correctly powers up the appropriate motor to seek |
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## References
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[1] [Building instructions](http://legolab.cs.au.dk/DigitalControl.dir/NXT/Lesson6.dir/ExpressBot.pdf)
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[2] [Tom Dean's Notes](http://cs.brown.edu/people/tld/courses/cs148/01/vehicles/vehicles.htm) |
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[2] [Tom Dean's Notes](http://cs.brown.edu/people/tld/courses/cs148/01/vehicles/vehicles.htm)
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[3] [The decibel scale with examples, in Danish](http://fys.dk/fipnet/1_oeret/11_temaer/116_skala/) |
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