December 2013
I'm working on a robot project that requires navigation and I'm trying to decide between an accelerometer and a gyroscope chip. Accelerometers are cheaper, but I've heard not as accurate. Is this true? When should I use one over the other?
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They are two different sensors. A gyro measures rotation about an axis. An accelerometer measures acceleration in a given direction. To create a true inertial navigation system, one needs to accumulate both acceleration and rotation information in all three axes (x, y, & z). An accelerometer can be used to make a rotation measurement. It will not be as accurate as traditional rotation sensors.
Nevertheless, for making "guidance" sensors as opposed to "navigation" sensors, there are many (relatively) inexpensive three axis monolithic sensors based on MEMs accelerometers. Guidance is used to provide orientation feedback whereas a navigation sensor is used to place location after so many seconds, hours, or days.
For further study on the differences, look at the physics behind a ring laser or fiber optic gyro (it only takes a few minutes to figure out what is going on). The difference in what the sensors are measuring becomes apparent ([url=http://en.wikipedia.org/wiki/Ring_laser_gyroscope]http://en.wikipedia.org/wiki/Ring_laser_gyroscope[/url]).
