Position estimation system and estimation method
A navigation system includes a GPS reception unit receiving a GPS signal, an observation unit observing observables including a GPS vehicle position based on the received GPS signal, and an estimation unit estimating state quantities concerning the present location based on the observables and on the Kalman filter, the estimation unit calculates prediction values of the state quantities and errors of the prediction values, calculates estimation values of the state quantities and errors of the estimation values, based on the prediction values, the errors of the prediction values and errors of the observables observed, and, when calculating the estimation values and the errors of the estimation values, assigns a weight based on a period from a first timing to a second timing in which the GPS signal received in the first timing is not reflected in observation of the GPS vehicle position, to an error of the GPS vehicle position.
1. A position estimation system, comprising:
a speed sensor that detects a speed of a mobile body which is a vehicle or a pedestrian;
a gyro sensor that detects an angular speed by rotation of the mobile body;
a GPS receiver that receives a GPS signal; and
a controller that includes a CPU and a memory;
wherein the controller comprises:
an observation circuit that observes, in every predetermined observation interval, the speed, a position and an azimuth of the mobile body as observables based on a signal which indicates the speed and which is outputted from the speed sensor, a signal which indicates the angular speed and which is outputted from the gyro sensor, and a GPS signal received by the GPS receiver; and
an estimation circuit that estimates state quantities concerning a present location based on the observables observed by the observation circuit and on a Kalman filter,
wherein the estimation circuit
calculates prediction values of the state quantities, and errors of the prediction values,
calculates estimation values of the state quantities and errors of the estimation values, based on the prediction values, the errors of the prediction values and errors of the observables which are observed by the observation circuit, and
at a time of calculating the estimation values and the errors of the estimation values,
assigns a weight based on a period after an error based on a first influence relating to reception of the GPS signal occurs to a GPS positioning position, until an error based on a second influence different from the first influence occurs to the GPS positioning position, to the error of the GPS positioning position.
2. The position estimation system according to claim 1 ,
wherein the estimation circuit
at a time of calculating the estimation values and the errors of the estimation values,
assigns a weight based on a period after an error based on an influence relating to reception of the GPS signal occurs to the GPS positioning position until the error is eliminated, to the error of the GPS positioning position.
3. The position estimation system according to claim 2 ,
wherein the position estimation system is an on-vehicle system that is installed on a vehicle, and estimates the state quantities concerning a present location of the vehicle.
4. The position estimation system according to claim 1 ,
wherein the position estimation system is an on-vehicle system that is installed on a vehicle, and estimates the state quantities concerning a present location of the vehicle.
5. The position estimation system according to claim 1 ,
wherein the position estimation system is an on-vehicle system that is installed on a vehicle, and estimates the state quantities concerning a present location of the vehicle.
6. An estimation method performed by a position estimation system having:
a speed sensor that detects a speed of a mobile body which is a vehicle or a pedestrian;
a gyro sensor that detects an angular speed by rotation of the mobile body;
a GPS receiver that receives a GPS signal; and
a controller that includes a CPU and a memory; comprising
by an observation circuit of the controller, observing in every predetermined observation interval, the speed, a position and an azimuth of the mobile body as observables based on a signal which indicates the speed and which is outputted from the speed sensor, a signal which indicates the angular speed and which is outputted from the gyro sensor, and a GPS signal received by the GPS receiver;
by an estimation circuit by the controller, estimating state quantities concerning a present location based on a Kalman filter and observables including a GPS positioning position based on a GPS signal, comprising:
by an estimation circuit, calculating prediction values of the state quantities, and errors of the prediction values;
calculating estimation values of the state quantities and errors of the estimation values, based on the prediction values, the errors of the prediction values and errors of the observables; and
at a time of calculating the estimation values and the errors of the estimation values by an estimation circuit,
assigns a weight based on a period after an error based on a first influence relating to reception of the GPS signal occurs to the GPS positioning position, until an error based on a second influence different from the first influence occurs to the GPS positioning position, to the error of the GPS positioning position.
7. The estimation method according to claim 6 ,
wherein at a time of calculating the estimation values and the errors of the estimation values,
a weight based on a period after an error based on an influence relating to reception of the GPS signal occurs to the GPS positioning position, until the error is eliminated is assigned to the error of the GPS positioning position.
8. The estimation method according to claim 7 ,
wherein state quantities concerning a present location of a vehicle is estimated.
9. The estimation method according to claim 6 ,
wherein state quantities concerning a present location of a vehicle is estimated.
10. The estimation method according to claim 6 ,
wherein state quantities concerning a present location of a vehicle is estimated.