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Thread: Altitude Hold

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    Altitude Hold

    Hi, I would like to make my quadrocopter able to maintain automatically its altitude. What are the advantages and disadvantages between an ultrasonic sensor and a barometric pressure sensor?

    I use an Arduino Uno with the 1.9 shield with gyrometers and accelerometers. Are there still connections available for an additional sensor? And which ones?

    Thanks in advance for your answers!

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    The UNO does not have enough code space to use the AQ altitude hold.

    Barometers are less accurate than sonar. Sonar has a short range - only about 2-3m. Above 2 or 3 m the sonar can't see the ground and therefor is useless - barometer and/or accelerometers must be used.
    push the envelope, watch it bend

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    How do you know that the UNO does not have enough code space, where can we see that? And if I clean up the code, are there enough ports on the shield?




    Quote Originally Posted by wooden View Post
    The UNO does not have enough code space to use the AQ altitude hold.

    Barometers are less accurate than sonar. Sonar has a short range - only about 2-3m. Above 2 or 3 m the sonar can't see the ground and therefor is useless - barometer and/or accelerometers must be used.

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    You can see that by enabling altitude hold and then trying to upload the code to an Uno or Pro Mini... it just won't fit. Trust me, we tried this about a year ago. The Atmega328p that is used on the Uno/Pro Mini has 32KB of flash memory but 1KB of that is taken up by the bootloader. You could potentially remove the bootloader but you won't be able to program it over USB anymore - you would have to use an AVR ISP (USBasp, etc.) or another Arduino to get the software onto the chip.

    There are plenty of extra ports. The barometer will connect over I2C, which shares ports with the accel and gyro. A sonar is usually connected to an analog port, but it could also go into a spare receiver/motor port, serial port, or if you buy an I2C sonar, it could also go on I2C. Just depends on what sonar you choose.
    Last edited by wooden; 04-11-2013 at 01:10 AM.
    push the envelope, watch it bend


 

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