SENSOR CALIBRATION DEVICE, AND SENSOR CALIBRATION METHOD

• US 20100168957A1
• Filed: 11/30/2009
• Published: 07/01/2010
• Est. Priority Date: 12/25/2008
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: TAKAHASHI, Yoshihiko
• Granted Patent: US 8,527,141 B2
• Time in Patent Office: Days
• US Class Current: 701/34
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A sensor calibration ECU includes: a calibratability determination portion that determines whether or not a distance image sensor is in a calibratable state on the basis of at least one of the state of a vehicle and the state of a road surface on which the vehicle is positioned; and a calibration execution portion that calibrates the distance image sensor on the basis of a pre-found distance (=reference distance) between the distance image sensor and the road surface on which the vehicle is positioned, when it is determined by the calibratability determination portion that the distance image sensor is in the calibratable state.

Claims

1. A sensor calibration device that calibrates a distance-measuring sensor that is mounted in a vehicle, characterized by comprising:

a calibratability determination portion that determines whether or not the distance-measuring sensor is in a calibratable state based on at least one of state of the vehicle and state of a road surface on which the vehicle is positioned; and

a calibration execution portion that calibrates the distance-measuring sensor based on a pre-found distance between the distance-measuring sensor and the road surface on which the vehicle is positioned, when it is determined by the calibratability determination portion that the distance-measuring sensor is in the calibratable state.

2. The sensor calibration device according to claim 1, wherein

the calibratability determination portion determines whether or not the distance-measuring sensor is in the calibratable state according to whether or not the vehicle is substantially parallel to the road surface.

3. The sensor calibration device according to claim 1, wherein:

the distance-measuring sensor is a distance image sensor at least a portion of whose detection region is the road surface; and

the calibratability determination portion determines whether or not the distance image sensor is in the calibratable state based on a result of detection by the distance image sensor.

4. The sensor calibration device according to claim 3, wherein

the calibratability determination portion determines whether or not the vehicle is substantially parallel to the road surface based on the result of detection by the distance image sensor, and then determines whether or not the distance image sensor is in the calibratable state according to a result of determination as to whether or not the vehicle is substantially parallel to the road surface.

5. The sensor calibration device according to claim 4, wherein

the calibratability determination portion determines that the vehicle is substantially parallel to the road surface when an amount of change in distance detected by each of photosensitive cells contained in the distance image sensor during a pre-set time is less than or equal to a pre-set threshold value.

6. The sensor calibration device according to claim 4, wherein

the calibratability determination portion determines that the vehicle is substantially parallel to the road surface when, regarding a plurality of pre-set photosensitive cells among photosensitive cells contained in the distance image sensor, an amount of change in distance detected by each of the pre-set photosensitive cells during a pre-set time is less than or equal to a pre-set threshold value.

7. The sensor calibration device according to claim 3, wherein

the calibratability determination portion finds a variance of brightnesses detected by photosensitive cells that are contained in the distance image sensor, and determines whether or not the distance image sensor is in the calibratable state according to whether or not the variance is less than or equal to a pre-set threshold value.

8. The sensor calibration device according to claim 3, wherein:

each of photosensitive cells contained in the distance image sensor is set in a corresponding one of a plurality of pre-set divided regions;

the calibratability determination portion, with regard to each of the divided regions, finds a variance of brightnesses detected by the photosensitive cells contained in a divided region, and determines whether or not the divided region of the distance image sensor is in the calibratable state according to whether or not the variance is less than or equal to a pre-set threshold value; and

the calibration execution portion calibrates the divided region of the distance image sensor that is determined as being in the calibratable state by the calibratability determination portion.

9. The sensor calibration device according to claim 3, further comprising

a correction coefficient storage portion that stores a correction coefficient for use for correcting a detected value from the distance image sensor, with regard to each of photosensitive cells contained in the distance image sensor,

wherein the calibration execution portion calibrates the distance image sensor with regard to a plurality of brightnesses, and records in the correction coefficient storage portion a correction coefficient found as a result of calibration so that the correction coefficient is associated in correspondence with information about the brightness.

10. The sensor calibration device according to claim 1, further comprising

a state detection portion that detects state of the vehicle,

wherein the calibratability determination portion determines whether or not the distance-measuring sensor is in the calibratable state based on a result of detection by the state detection portion.

11. The sensor calibration device according to claim 10, wherein

the state detection portion includes at least one of an acceleration sensor that detects acceleration of the vehicle, an inclination detection sensor that detects inclination of the vehicle, and a vehicle speed sensor that detects vehicle speed of the vehicle.

12. The sensor calibration device according to claim 11, wherein

the inclination detection sensor detects at least one of yaw angle, pitch angle and roll angle of the vehicle.

13. A sensor calibration method that calibrates a distance-measuring sensor that is mounted in a vehicle, characterized by comprising the steps of:

determining whether or not the distance-measuring sensor is in a calibratable state based on at least one of state of the vehicle and state of a road surface on which the vehicle is positioned; and

calibrating the distance-measuring sensor based on a pre-found distance between the distance-measuring sensor and the road surface on which the vehicle is positioned, when it is determined that the distance-measuring sensor is in the calibratable state.