Abstract: Terrain navigation apparatus (1) for a stationary or moving vehicle (2) when the apparatus (1) is mounted thereon, including a system (3) for determining position, velocity, altitude and attitude incorporating at least six sensing means operable to provide signals indicative of a first measured height (5), a first velocity (7) and a first position (9) of the vehicle (2), scanning means (11) operable to scan terrain (13) around the vehicle (2) and measure a range (15) from the vehicle (2) thereto, first combining means (17) for combining signals indicative of the first measured height, the range and the first position (5, 15, 9) of the vehicle (2), together with error estimates (19) associated therewith, and for outputting results of said combining process, error-estimating means (21) for receiving as input signals results of said combining process and for providing said error estimates(19), such that the error-estimating means (21) and first combining means (17) operatively interact to effect terrain navigati

Abstract: Terrain navigation apparatus (1) for a legged animal (2) traversing terrain (3) including a first system (4) for determining position, velocity and heading of the legged animal incorporating sensing means for sensing inertial motion in six degrees of freedom operable to provide signals indicative of a first velocity (5a), a first heading (7a) and a first position (9a) of the legged animal (2), contact means (11) for establishing, in a velocity profile describing motion of either foot of the legged animal, a period where the velocity should be zero (17), which period corresponds to full or partial contact of the respective foot (13a, 13b) with surrounding terrain (3), and error-estimating means (15) for receiving as input signals the velocity profile during the period and for providing as output signals estimates of errors (19) associated with the sensing means output signals, which errors operatively interact with the output signals of the first system to effect terrain navigation of the legged animal (2).