Inertial Technology

Inertial measurement uses accelerometers to measure movement. Inertial measurement systems require initializing (alignment) at a known point in order to provide a reference (or home) from which the system then measures. Inertial measurement technology has been in use for many years, but is now receiving renewed interest as systems become small enough to fit on a single integrated circuit.

Advantages and Disadvantages

Advantages	Disadvantages
No line-of-sight required Tracker can be entirely built into the tool	Not accurate enough to meet demands of medical market (errors in order of millimeters in under a minute) Error increases over time (drift) Need a home/reference position to initialize the system and periodically remove drift error during use Electronics required in the tool

Summary

For applications requiring high accuracy, such as medical, inertial systems are typically not accurate enough. The time required by a typical medical application and the degradation over time (of inertial technology) is not acceptable.