Embedded Files
Initial Predictions
Initial Predictions
While our algorithm focuses on analyzing the signals for the whole song, we analyzed a few moves to understand the individual motions better. Many of the motions are repeated in the song.
Assuming that the majority of moves are in time with the music, we predict that the most dominant frequencies are those that are multiples of the tempo of the song.
The following motions are taken from the song Take on Me by a-ha. The tempo of the song is 168.61 bpm (beats per minute), or 2.81 Hz.
"The Epitome of the '80s"* Move
"The Epitome of the '80s"* Move
Game Motion
Game Motion
Player Motion
Player Motion
Prediction
Prediction
Figure 1: Predictions in both time and frequency domain for the "Epitome of the '80s"* move
Figure 1: Predictions in both time and frequency domain for the "Epitome of the '80s"* move
- For the x-axis acceleration, we expect one dominant frequency at about 1.4Hz to account for the side to side movement.
- For the y-axis acceleration, we predict that there will be one dominant frequency at 2.8Hz to account for the up and down movement that occurs on the beat.
- For the z-axis acceleration, there should be one dominant frequency for the rotation from side to side (the side to side motion isn't entirely linear, and we expect there to be some centripetal acceleration.).
Figure 2: Raw accelerometer data
Figure 2: Raw accelerometer data
The above graph shows the raw accelerometer data recorded for the three axes.
While the data wasn't collected at a particularly high frequency, the overall shapes of the data look similar to our predictions made above.
Figure 3: DFT of accelerometer data
Figure 3: DFT of accelerometer data
The graphs above show the magnitude of the accelerometer data in the frequency domain for the above motion.
In the x-axis, there are two major frequencies (2.8 Hz and 4.3 Hz).
In the y- and z- axes, there are three major frequencies (1.4 Hz, 2.8 Hz, 4.3 Hz).
Motion Analysis
Motion Analysis
The major peaks are multiples of the tempo. The peaks at around 2.8 Hz are for the movements that land on the beat (the downward motion), while the peaks at at 1.4 Hz correspond to the moves that occur every two beats (the sweeping from side to side). While the data doesn't match our predictions exactly, we recognize that the dominant frequencies are multiples of the tempo, suggesting that these motions were made with intent to line up with the beat of the song.
Note: the prominent spike at 0 Hz in the y-axis plot is related to the acceleration of gravity, which is constantly picked up by the accelerometer.
The 'Helicopter'* Gold** Move
The 'Helicopter'* Gold** Move
Game Motion
Game Motion
Player Motion
Player Motion
Prediction
Prediction
Figure 4: Predictions in both time and frequency domain for the "Helicopter"* Gold** move
Figure 4: Predictions in both time and frequency domain for the "Helicopter"* Gold** move
- For the x-axis acceleration, there should be one dominant frequency that represents the single, circular rotation.
- For the y-axis acceleration, we have omitted the bouncing that the dancer does and anticipate there not be a dominant frequency (and simply have a spike at 0 Hz to account for gravity).
- For the z-axis direction, we predict that there will only be one dominant frequency that represents the centripetal acceleration.
Figure 5: Raw accelerometer data
Figure 5: Raw accelerometer data
The above graph shows the raw accelerometer data recorded for the three axes.
While the data wasn't collected at a particularly high frequency, the overall shapes of the data look similar to our predictions made above; for example, the y-axis acceleration remains fairly constant while the z-axis acceleration emulates that sinusoidal wave.
Figure 6: DFT of accelerometer data
Figure 6: DFT of accelerometer data
The graphs above show the magnitude of the accelerometer data in the frequency domain for the above motion.
In the x-axis, there is a major frequency at about 0.7 Hz, as predicted.
In the y- and z- axis, there is a major frequency at 0.54 Hz which differs from our predictions.
Motion Analysis
Motion Analysis
The significant peak in the x-axis acceleration at 0.7 Hz aligns with our prediction. The frequency at which the data was recorded (10 Hz) was probably not frequent enough to get the desired results, and there is a lot of noise in the data that could be filtered. Overall, though, the data presented the general shape that we anticipated when creating our motion model.
* These are not the actual names of these dance moves. We have no idea what the actual dance move names are. These names are our artistic interpretations of these moves.
** In Just Dance 3, "Gold Moves" refer to special moves within each song that offer extra points to the user if executed correctly.
** In Just Dance 3, "Gold Moves" refer to special moves within each song that offer extra points to the user if executed correctly.
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