1. Field of the Invention
The present invention relates to computer techniques, and more particularly to ergonomic inertial positioning systems and methods.
2. Description of the Related Art
Most current positioning techniques utilize signals from global positioning system (GPS) satellites or wireless local area networks (LAN) to calculate positions. GPS signals may be interrupted when the signal source is obstructed by buildings or forest. The accuracy of wireless-LAN-based positioning is easily affected by space factors, such as crowds.
Traditional inertial positioning measures the acceleration of an object to calculate the displacement thereof, and is thus not affected by the environment. Accelerators are more expensive as they offer improved accuracy in acceleration detection. Table 1 shows the exemplary accuracy and prices of accelerators.
TABLE 1PriceTime intervalHigh(~$750,000)Mid(~$100,000)Low(~$10,000)Distance1 hour0.3 km~0.5 km  1 km~3 km200 km~300 kmerror1 minute0.3 m~0.5 m0.5 m~3 m 30 m~50 m1 second0.01 m~0.02 m0.03 m~0.1 m0.3 m~0.5 m
Traditional inertial positioning suffers from the accumulated errors caused by sensor noise or numerical calculation. As measured acceleration is integrated twice for displacement calculation, displacement errors increase progressively with time.
Traditional inertial positioning immune to environmental factors is typically implemented in aircrafts, vehicles, and similar machines due to regular and smooth variation in their velocities, but may not work with objects moving in complex ways, such as animals and humans.