Patent ID: 7505865

Claim:
A velocity detecting system comprising: an acceleration sensor for obtaining detected acceleration corresponding to a result of that mobile body acceleration in a forward direction in a predetermined mobile body was added to a component of said forward direction being gravity acceleration operating on the mobile body; amount of height change calculating means for calculating an amount of height change of said mobile body in a predetermined measurement time, based on a surrounding pressure of said mobile body detected by a predetermined pressure sensor; and velocity calculating means for obtaining said mobile body acceleration by offsetting said forward direction component included in said detected acceleration based on the amount of height change, by utilizing a ratio of said forward direction component of said gravity acceleration to the gravity acceleration corresponds to a ratio of said amount of height change to a moving distance of said mobile body in said measurement time, and calculating a velocity of said mobile body at a measurement finish point by using the mobile body acceleration, based on a known velocity of said mobile body at a measurement start point.