Method and apparatus for measuring relative heading changes in a vehicular onboard navigation system

A method of measuring a change in the heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width which varies as a function of the curvature of said turn, comprising the steps of:

• measuring the distance each one of said wheels is rotated during said turn;
• providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other;
• providing a signal T having a magnitude corresponding to said track width which varies as a function of the curvature of said turn of said vehicle;
• and
• providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D and T, wherein said signal .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.

A method of measuring a change in the heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width, comprising the steps of:

• measuring the distance each of said wheels is rotated during said turn;
• providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other during said turn;
• providing a signal T having a magnitude corresponding to said track width which varies as a function of the geometric foreshortening of said track width during said turn of said vehicle;
• and
• providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D and T, wherein said signal .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.

A method of measuring the change in heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width which varies as a function of the curvature of said turn, comprising the steps of:

• measuring the distance each of said wheels is rotated during said turn,
• providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other during said turn;
• providing a signal AD having a magnitude corresponding to the average distance said wheels rotate during said turn;
• providing a signal T having a magnitude corresponding to said track width as determined by the equation:
• ##EQU6## wherein T.sub.F is the distance said wheels are spaced apart in an Ackerman-type vehicular steering system, P is the Pitman arm ratio in said system and B is the distance between the front and rear axles of said vehicle and providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D and T, wherein said signal .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.

An apparatus for measuring a change in heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width comprising:

• means for measuring the distance each one of said wheels is rotated during said turn;
• means responsive to said distance measuring means for providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other during said turn;
• means for measuring the velocity of said vehicle during said turn;
• means responsive to said velocity measuring means for providing a signal V having a magnitude corresponding to said velocity;
• means for providing a signal T having a magnitude corresponding to said track width;
• and
• means for providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D, T, and V, wherein said signal .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.

An apparatus for measuring a change in heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width which varies as a function of the curvature of said turn comprising:

• means for measuring the distance each one of said wheels is rotated during said turn;
• means responsive to said distance measuring means for providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other during said turn;
• means for providing a signal T having a magnitude corresponding to said track width which varies as a function of the curvature of said turn;
• and
• means for providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D and T, wherein said signal .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.

An apparatus for measuring a change in heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width, comprising:

• means for measuring the distance each of said wheels is rotated during said turn;
• means responsive to said distance measuring means for providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other during said turn;
• means for providing a signal T having a magnitude corresponding to said track width which varies as a function of the geometric foreshortening of said track width during a turn of said vehicle;
• and
• means for providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D and T, wherein said signal .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.

An apparatus of measuring a change in heading of a road vehicle during a turn, said vehicle having a pair of laterally spaced wheels which describe a track having a width which varies as a function of the curvature of said turn, comprising:

• means for measuring the distance each of said wheels is rotated during said turn;
• means responsive to said distance measuring means for providing a signal .DELTA.D having a magnitude corresponding to the difference in the measured distances, one of said wheels is rotated relative to the other during said turn;
• means responsive to said distance measuring means for providing a signal AD having a magnitude corresponding to the average distance said wheels rotate during said turn;
• means for providing a signal T having a magnitude corresponding to said track width as determined by the equation:
• ##EQU8## wherein T.sub.F is the distance said wheels are spaced apart in an Ackerman-type vehicular steering system, P is the Pitman arm ratio in said system and B is the distance between the front and rear axles of said vehicle;
• and means for providing a signal .DELTA..theta..sub.w in response to said signals .DELTA.D and T, wherein said .DELTA..theta..sub.w corresponds to the change in heading of said vehicle during said turn.