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A position detecting apparatus and method used in a navigation system, which can improve positional accuracy and bearing accuracy even in a system equipped with few sensors, are provided. A position detecting apparatus used in a navigation system for detecting a vehicle position includes: a sensor u

A position detecting apparatus and method used in a navigation system, which can improve positional accuracy and bearing accuracy even in a system equipped with few sensors, are provided. A position detecting apparatus used in a navigation system for detecting a vehicle position includes: a sensor unit including a vehicle speed sensor, an acceleration sensor, and an angular velocity sensor; and a dead reckoning calculating unit for calculating state quantity inclusive of a current vehicle position, a vehicle speed, and a vehicle attitude angle based on a signal output from each of the sensors at a predetermined periodic interval. The dead reckoning calculating unit includes: a movement calculating unit for calculating a movement during a period from a previous state quantity calculation time up to a current state quantity calculation time; a change amount detecting unit for calculating an amount of change in vehicle attitude; a movement resolving unit for resolving the movement into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; and a state quantity calculating unit for determining, by calculation, a vehicle position at the current state quantity calculation time using each of the components.

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1. A position detecting apparatus used in a navigation system for detecting a vehicle position, comprising: a sensor unit including a vehicle speed sensor for detecting a vehicle speed, an acceleration sensor for detecting vehicle acceleration, and an angular velocity sensor for detecting a vehicle

1. A position detecting apparatus used in a navigation system for detecting a vehicle position, comprising: a sensor unit including a vehicle speed sensor for detecting a vehicle speed, an acceleration sensor for detecting vehicle acceleration, and an angular velocity sensor for detecting a vehicle angular velocity; and a dead reckoning calculating unit for calculating state quantity inclusive of a current vehicle position, a vehicle speed, and a vehicle attitude angle based on a signal output from each of the sensors at a predetermined periodic interval,the dead reckoning calculating unit including:a counting unit for counting the number of vehicle speed pulses input from the vehicle speed sensor;a moving distance calculating unit for calculating a moving distance by multiplying the number of vehicle speed pulses by an interpulse distance;a change amount detecting unit for calculating an amount of change in vehicle attitude, including an amount of change in vehicle pitch angle and an amount of change in vehicle yaw angle;a movement vector calculating unit for calculating a movement vector during a period from a previous state quantity calculation time up to a current state quantity calculation time;a movement resolving unit for resolving the movement into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda state quantity calculating unit for determining, by calculation, a vehicle position pn at the current state quantity calculation time using each of the components according to the following expression: pn(k+1)=pn(k)+Tnbsb where pn=[NED]=[Northward⁢⁢distanceEastward⁢⁢distanceDownward⁢⁢distance]sb=[Np⁢L×cos⁡(E.2)×cos⁡(E.3)Np⁢L×cos⁡(E.2)×sin⁡(E.3)Np⁢L×sin⁡(E.2)]Tnb represents a transform matrix for transforming from a vehicle fixed coordinate system to a NED coordinate system; sb represents the moving distance vector; Np represents a number of vehicle speed pulses per sample time and L represents an interpulse distance; and the amount of change in vehicle pitch angle and the amount of change in vehicle yaw angle are represented by Ė2 and Ė3, respectively. 2. The position detecting apparatus according to claim 1, further comprising: a state quantity correcting unit that performs state quantity correction processing at a second periodic interval longer than the predetermined periodic interval at which the dead reckoning calculating unit calculates a state quantity based on a vehicle moving speed measured using an output signal of the vehicle speed sensor and the state quantity calculated with the dead reckoning calculating unit to thereby correct the state quantity calculated with the dead reckoning calculating unit,the state quantity correcting unit including:a speed resolving unit for resolving the measured moving speed into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda corrected state quantity calculating unit for determining, by calculation, a corrected state quantity based on each of the speed components, and the state quantity calculated with the dead reckoning calculating unit. 3. The position detecting apparatus according to claim 2, wherein the measured moving speed is represented by V, and the speed resolving unit resolves the moving speed into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the following expressions: Vehicle longitudinal component=|V|×cos(Ė2)×cos(Ė3)Vehicle lateral component=|V|×cos(Ė2)×sin(Ė3)Vehicle vertical component=|V|×sin(Ė2) 4. The position detecting apparatus according to claim 1, wherein the change amount detecting unit calculates the amount of change in vehicle pitch angle and the amount of change in vehicle yaw angle based on a vehicle attitude angle calculated by the state quantity calculating unit. 5. A position detecting method used in a navigation system for calculating state quantity inclusive of a current vehicle position, a vehicle speed, and a vehicle attitude angle based on a signal output from a vehicle speed sensor for detecting a vehicle speed, an acceleration sensor for detecting vehicle acceleration, and an angular velocity sensor for detecting a vehicle angular velocity based on a dead reckoning process, comprising: a first step of counting the number of vehicle speed pulses input from the vehicle speed sensor;a second step of calculating a moving distance by multiplying the number of vehicle speed pulses by an interpulse distance;a third step of calculating an amount of change in vehicle attitude, including an amount of change in vehicle pitch angle and an amount of change in vehicle yaw angle;a fourth step of calculating a movement vector during a period from a previous state quantity calculation time up to a current state quantity calculation time using a signal output from the vehicle speed sensor;a fifth step of resolving the movement into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda sixth step of determining, by calculation using a processor, a vehicle position pn at the current state quantity calculation time using each of the components according to the following expression: pn(k+1)=pn(k)+Tnbsb where pn=[NED]=[Northward⁢⁢distanceEastward⁢⁢distanceDownward⁢⁢distance]sb=[Np⁢L×cos⁡(E.2)×cos⁡(E.3)Np⁢L×cos⁡(E.2)×sin⁡(E.3)Np⁢L×sin⁡(E.2)]Tnb represents a transform matrix for transforming from a vehicle fixed coordinate system to a NED coordinate system; sb represents the moving distance vector; Np represents a number of vehicle speed pulses per sample time and L represents an interpulse distance; and the amount of change in vehicle pitch angle and the amount of change in vehicle yaw angle are represented by Ė2 and Ė3, respectively. 6. The position detecting method according to claim 5, further comprising: a fifth step of measuring a vehicle moving speed using an output signal of the vehicle speed sensor at a second periodic interval longer than the predetermined periodic interval at which a state quantity is calculated based on the dead reckoning process; anda sixth step of performing state quantity correction processing based on the measured vehicle moving speed and the state quantity calculated through the dead reckoning process to thereby correct the state quantity calculated through the dead reckoning process,the sixth step including:a resolving step of resolving the measured moving speed into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda calculating step of determining, by calculation, a corrected state quantity based on each of the speed components, and the state quantity calculated through the dead reckoning calculating process. 7. The position detecting method according to claim 6, wherein the measured moving speed is represented by V, and in the resolving step, the moving speed is resolved into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the following expressions: Vehicle longitudinal component=|V|×cos(Ė2)×cos(Ė3)Vehicle lateral component=|V|×cos(Ė2)×sin(Ė3)Vehicle vertical component=|V|×sin(Ė2) 8. The position detecting method according to claim 5, wherein in the second step, the amount of change in vehicle pitch angle and the amount of change in vehicle yaw angle are calculated based on a vehicle attitude angle calculated through the dead reckoning process. 9. A position detecting apparatus used in a navigation system for detecting a vehicle position, comprising: a sensor unit including a vehicle speed sensor for detecting a vehicle speed, an acceleration sensor for detecting vehicle acceleration, and an angular velocity sensor for detecting a vehicle angular velocity; and a dead reckoning calculating unit for calculating state quantity inclusive of a current vehicle position, a vehicle speed, and a vehicle attitude angle based on a signal output from each of the sensors at a predetermined periodic interval,the dead reckoning calculating unit including:a counting unit for counting the number of vehicle speed pulses input from the vehicle speed sensor;a moving distance calculating unit for calculating a moving distance by multiplying the number of vehicle speed pulses by an interpulse distance;a change amount detecting unit for calculating an amount of change in vehicle attitude wherein the change amount detecting unit detects a change amount of vehicle yaw angle as the amount of change in vehicle attitude;a movement vector calculating unit for calculating a movement vector during a period from a previous state quantity calculation time up to a current state quantity calculation time;a movement resolving unit for resolving the movement into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda state quantity calculating unit for determining, by calculation, a vehicle position pn at the current state quantity calculation time using each of the components according to the following expression: pn(k+1)=pn(k)+Tnbsb where pn=[NED]=[Northward⁢⁢distanceEastward⁢⁢distanceDownward⁢⁢distance]sb=[Np⁢L×cos⁡(E.3)Np⁢L×sin⁡(E.3)0]Tnb represents a transform matrix for transforming from a vehicle fixed coordinate system to a NED coordinate system; sb represents the moving distance vector; Np represents a number of vehicle speed pulses per sample time and L represents an interpulse distance; and the amount of change in vehicle yaw angle is represented by Ė3. 10. The position detecting apparatus according to claim 9, wherein the change amount detecting unit calculates the amount of change in vehicle yaw angle using an attitude angle calculated by the state quantity calculating unit. 11. The position detecting apparatus according to claim 8, The position detecting apparatus according to claim 9, further comprising: a state quantity correcting unit that performs state quantity correction processing at a second periodic interval longer than the predetermined periodic interval at which the dead reckoning calculating unit calculates a state quantity based on a vehicle moving speed measured using an output signal of the vehicle speed sensor and the state quantity calculated with the dead reckoning calculating unit to thereby correct the state quantity calculated with the dead reckoning calculating unit,the state quantity correcting unit including:a speed resolving unit for resolving the measured moving speed into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda corrected state quantity calculating unit for determining, by calculation, a corrected state quantity based on each of the speed components, and the state quantity calculated with the dead reckoning calculating unit;wherein the measured moving speed is represented by V, and the speed resolving unit resolves the moving speed into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the following expressions: Vehicle longitudinal component=|V|×cos(Ė3)Vehicle lateral component=|V|×sin(Ė3)Vehicle vertical component=0 12. A position detecting method used in a navigation system for calculating state quantity inclusive of a current vehicle position, a vehicle speed, and a vehicle attitude angle based on a signal output from a vehicle speed sensor for detecting a vehicle speed, an acceleration sensor for detecting vehicle acceleration, and an angular velocity sensor for detecting a vehicle angular velocity based on a dead reckoning process, comprising: a first step of counting the number of vehicle speed pulses input from the vehicle speed sensor;a second step of calculating a moving distance by multiplying the number of vehicle speed pulses by an interpulse distance;a third step of calculating an amount of change in vehicle attitude wherein in-the second step, a change amount of vehicle yaw angle is detected as the amount of change in vehicle attitude;a fourth step of calculating a movement vector during a period from a previous state quantity calculation time up to a current state quantity calculation time using a signal output from the vehicle speed sensor;a fifth step of resolving the movement into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda sixth step of determining, by calculation using a processor, a vehicle position pn at the current state quantity calculation time using each of the components according to the following expression: pn(k+1)=pn(k)+Tnbsb where pn=[NED]=[Northward⁢⁢distanceEastward⁢⁢distanceDownward⁢⁢distance]sb=[Np⁢L×cos⁡(E.3)Np⁢L×sin⁡(E.3)0]Tnb represents a transform matrix for transforming from a vehicle fixed coordinate system to a NED coordinate system; sb represents the moving distance vector; Np represents a number of vehicle speed pulses per sample time and L represents an interpulse distance; and the amount of change in vehicle yaw angle is represented by Ė3. 13. The position detecting method according to claim 12, wherein in the second step, the amount of change in vehicle yaw angle is calculated using an attitude angle calculated through the dead reckoning process. 14. The position detecting method according to claim 12, further comprising: a fifth step of measuring a vehicle moving speed using an output signal of the vehicle speed sensor at a second periodic interval longer than the predetermined periodic interval at which a state quantity is calculated based on the dead reckoning process; anda sixth step of performing state quantity correction processing based on the measured vehicle moving speed and the state quantity calculated through the dead reckoning process to thereby correct the state quantity calculated through the dead reckoning process,the sixth step including:a resolving step of resolving the measured moving speed into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the amount of change in vehicle attitude; anda calculating step of determining, by calculation, a corrected state quantity based on each of the speed components, and the state quantity calculated through the dead reckoning calculating process;wherein the measured moving speed is represented by V, and in the resolving step, the moving speed is resolved into a vehicle longitudinal component, a vehicle lateral component, and a vehicle vertical component based on the following expressions: Vehicle longitudinal component=|V|×cos(Ė3)Vehicle lateral component=|V|×sin(Ė3)Vehicle vertical component=0