Navigation system for land vehicles

Claim 1

A navigation device for a land vehicle comprising a) a storage device storing geographical data; b) sensors for detecting existing travel data; c) a calculating unit for calculating a safe driving speed of a particular section of road based on said geographical data stored in said storage device and for calculating an actual speed based on said travel data detected by said sensors; d) a comparison device for comparing said safe driving speed and said actual speed calculated by said calculating unit; and e) an information delivery system for indicating an unsafe condition if said actual driving speed is not within said safe driving speed, wherein said geographical data stored in said storage device includes road edges and associated angles which define a section of road between two base points, wherein a curvature value is determined based on a length of a road edge and its associated angle, wherein said safe driving speed is determined based on said curvature value, and wherein said calculating unit further: (i) determines a virtual stopping point from a current position based on said actual speed and a maximum deceleration value thereby defining a first line between said current position and said virtual stopping point; ii) determines an actual stopping point based on said actual speed, said maximum deceleration value, and said curvature of a future section of road thereby defining a second line between said current position and said actual stopping point; and (iii) determines an angle between said first line and said second line.

Claim 7

A method for providing road information to comprising the steps of: a) determining a limit speed to be maintained for safe travel over a length of road based on stored geographical data regarding the road; b) comparing said limit speed determined in step (a) with an actual speed; c) determining whether a dangerous condition exists based on the comparison of step (b); and d) warning said driver if a dangerous condition is determined to exist in step (c), wherein said step of determining said limit speed includes calculating a curvature value based on edges associated with a road and corresponding angles which are included in said stored geographical data, and wherein said step of determining said limit speed includes the sub-steps of: (i) determining a virtual stopping point from a current position based on said actual speed and a maximum deceleration value thereby defining a first line between said current position and said virtual stopping point; (ii) determining an actual stopping point based on said actual speed, said maximum deceleration value, and said curvature thereby defining a second line between said current position and said actual stopping point; and (iii) determining an angle between said first line and said second line.

Claim 8

A method for providing road information to comprising the steps of: a) determining a limit speed to be maintained for safe travel over a length of road based on stored geographical data regarding the road; b) comparing said limit speed determined in step (a) with an actual speed; c) determining whether a dangerous condition exists based on the comparison of step (b); and d) warning said driver if a dangerous condition is determined to exist in step (c), wherein said step of determining said limit speed includes calculating a curvature value based on edges associated with a road and corresponding angles which are included in said stored geographical data, and wherein said step of determining said limit speed includes the sub-steps of: (i) determining a virtual stopping point from a current position based on said actual speed and a maximum deceleration value thereby defining a first line between said current position and said virtual stopping point; (ii) determining an actual stopping point based on said actual speed, said maximum deceleration value, and said curvature thereby defining a second line between said current position and said actual stopping point; and (iii) determining an angle between said first line and said second line.