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I made an investigation on the effect that the battery has on the car speed. Data has been acquired by running car1 on a circle with constant steer and engine input. The steer has always been set to -64. The starting position of the car has always been about (3000, 3600) in global coordinates (this if you want to make considerations connected to the test-bed slope). The voltage of the battery was measured both before turning on the car (while off) and just before run ca2 (while on). The full data gathered and the detailed description of how the experiments were performed can be found in my folder on Dropbox in "../backup/data/battery_7-30-2013".

  • Experiment 1: the initial voltage was kept constant while varying the pwm signal. See figure experiment1.png. The speed always reaches a peak and then decrease to a steady state value. The second run starts more or less from the steady state value. The PWM does not seem to affect neither the time constant nor the steady state value that is more or less always 200 mm/s below the peak.
  • Experiment 2: the pwm was kept constant while varying the initial voltage. The car is run only the first time.
  • Experiment 3: the car is run 3 times in a row to check if the third time the speed dynamics changes again.
  • Experiment 5: the car is left turned on for 25 minutes before running to check if the capacitor gets discharged even if the car is not running.

TODO: I wanted to perform another experiment to check if the capacitor gets charged again to its original level after the car runs but car1 broke just before I could perform the experiment.

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