I have a quick question. When it comes to the values coming out of the accelerometer, how do I maniuplate these values and convert them to actual acceleration? I have been looking into this a lot, but I think I am missing the big picture…
Thank you
Technic-R-C
Tech,
Are you asking how to convert a single instantaneous value (like 42) from the accelerometer into meters per second^2; or ar you asking how to use a series of measurememnts to determine how the device’s acceleration, velocity and position changed over time?
Blake
I do not understand what the number 42 represents therefore making it hard to convert to a single instantaneous acceleration value through unit analysis (m/s^2). So the first part…
Thank you
Technic-R-C
Turn the accelerometer on its side and get a reading. What ever value that is will be 9.8 m/s/s (1G). You could turn it on another axis and see if the number is the same (I imagine it should be?) and then the final question is if the values are linear.
The VEX accelerometer returns a voltage 0 to 5 Volts for each axis. The voltage reading is digitized using the PIC18F8520 10-Bit Analog to Digital Converter (ADC) to a raw integer value between 0 and 1023. Using this information, you can scale the raw reading to your desired units (G’s) for measuring acceleration or degrees/radians for measuring angles (tilt).
I have been working on this myself…
Wikipedia says that Acceleration “is the change in velocity over time”.
I was planning to measure the Analog Outputs of the Accelerometer, over a given distance, and recording the time. The Vex Controller should be able to handle the Timing, so you only need to setup a known distance (e.g. 10-15 Meters), and record a Time Stamp and the appropriate Axis, or all three, if you want to see how they all vary. I would suggest a Straight Course, for starters (think like Drag Racing).