This article is about Measuring Angular Position with Gyroscope for hexarotor. For example if we get data with 250 Hz sampling frequency, we can multiply 250 with 60 seconds to compute how much data stored in one minute. If gyroscope gives value 65 for each degree per second. We can compute output value as gyroscope out/250=3.8415. Following expression shows angle value equation.
1500*Gyroscope output * 0,0749=angle
The primary hardware connections to use a gyro are power and a communication interface. Gyros can have either a digital or analog communication interface. Gyros with a digital interface usually use either the SPI or I2C communication protocols. Using these interfaces allow for an easy connection to a host microcontroller. One limitation of a digital interface is max sample rate. I2C has a max sample rate of 400Hz. SPI, on the other hand, can have a much higher sample rate.
MEMS gyros are generally low power devices. Operating currents are in the mA range. The supply voltage for gyros is usually 5V or less. Digital gyros can have selectable logic voltages or operate at the supply voltage. For any digital interface, remember to connect 5V to 5V lines and 3.3V to 3.3V lines. Also, gyros with digital interfaces can have low power and sleep modes that allow them to be used in battery powered applications. Sometimes this is an advantage over an analog gyro.
Electronical Schematics of Gyroscope
Gyroscope is selected digital in order to work compatible with flight controllers microcontroller. I2C port will be used in this system. Unmanned Aerial Vehicles rotates a little amount with respect to time for rotational orientation. Thus sensitivity is more important than large scale. In table right, most common digital gyroscopes and their specifications are shown.
For Measuring Angular Position with Gyroscope, MPU-6000 is selected because of its range, sensivity and more connection options. From Datasheet 250°/s is selected for our system. With this selection 0.00381°/ s angular velocity and correspond to this value, 0.36 ° angle will be minimum measurable values.
X axis has 33 kHz, Y axis has 30 kHz, Z axis 27 kHz has natural frequency. Our systems rotation will not be close to natural frequency. Frequency specification is suitable.
Thereby changing of measurement will not be inaccurate. In datasheet, between -40°C and +85°C temperature zone measurement is change %2. This value is acceptable for our system.
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