US-12625250-B2 - Vehicle speed calculation device

US12625250B2US 12625250 B2US12625250 B2US 12625250B2US-12625250-B2

Abstract

The vehicle speed calculation device includes a target category determination unit, a vehicle speed calculation unit, a positional relationship calculation unit, and a vehicle speed correction unit. The positional relationship calculation unit calculates the positional relationship between the vehicle and the fixed target in a height direction. The vehicle speed correction unit increases, when the target is an object on a road, degree of correction of the vehicle speed using the relative vehicle speed compared to when the target is an upper object.

Inventors

Toshinori Okita

Assignees

TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date: 20260512
Application Date: 20231127
Priority Date: 20230201

Claims (12)

1 . A vehicle speed calculation device that calculates a corrected vehicle speed of a vehicle, the vehicle speed calculation device comprising: a radar sensor; a wheel speed sensor; and one or more processors configured to: determine whether a fixed target present in front of the vehicle is a road object or an upper object based on a received electric power of the radar sensor of the vehicle; calculate a detected vehicle speed of the vehicle based on a detection result of the wheel speed sensor of the vehicle; calculate a positional relationship between the vehicle and the fixed target based on a detection result of the radar sensor; calculate a relative speed of the vehicle based on the calculated positional relationship; and calculate the corrected vehicle speed by correcting the detected vehicle speed based on the relative speed of the fixed target with respect to the vehicle that is detected by the radar sensor and the positional relationship, wherein; the one or more processors are configured to calculate, when the fixed target is the road object, the positional relationship between the vehicle and the fixed target in a height direction based on an installation height of the radar sensor from a road surface; the one or more processors are configured to calculate, when the fixed target is the upper object, the positional relationship between the vehicle and the fixed target in the height direction based on a vertical detection angle of the fixed target that is detected by the radar sensor or a vertical detection angle range of the radar sensor and a front-rear distance of the fixed target at a timing that the fixed target is lost from the vertical detection angle range; and the one or more processors are configured to increase, when the fixed target is the road object, a degree of correction of the detected vehicle speed using the relative speed and the positional relationship compared to when the fixed target is the upper object.
2 . The vehicle speed calculation device according to claim 1 , further comprising a data storage device that stores information on the received electric power of the radar sensor, wherein the one or more processors determine whether the fixed target is the road object or the upper object based on the information on the received electric power stored within a period until the vehicle passes the fixed target or a period until the received electric power dissipates.
3 . The vehicle speed calculation device according to claim 2 , wherein the one or more processors determine that the fixed target is the upper object, when: the front-rear distance of the fixed target at a timing that the received electric power has dissipated by an amount equal to or greater than a first predetermined value; a decrease rate of the received electric power with respect to the front-rear distance of the fixed target is equal to or greater than a second predetermined value; a decrease rate of the relative speed with respect to the front-rear distance of the fixed target is equal to or greater than a third predetermined value, and the fixed target is present within a right-left detection range of the radar sensor; and/or a right-left distance of the fixed target is equal to or less than a fourth predetermined value.
4 . The vehicle speed calculation device according to claim 1 , wherein the radar sensor is a millimeter wave radar.
5 . A method for calculating a corrected vehicle speed, the method comprising the steps of: determining whether a fixed target present in front of a vehicle is a road object or an upper object based on a received electric power of a radar sensor of the vehicle; calculating a detected vehicle speed of the vehicle based on a detection result of a wheel speed sensor of the vehicle; calculating a positional relationship between the vehicle and the fixed target based on a detection result of the radar sensor; calculating a relative speed of the vehicle based on the calculated positional relationship; and calculating the corrected vehicle speed by correcting the detected vehicle speed based on the relative speed of the fixed target with respect to the vehicle that is detected by the radar sensor and the positional relationship, wherein: when the fixed target is the road object, calculating the positional relationship between the vehicle and the fixed target in a height direction based on an installation height of the radar sensor from a road surface; when the fixed target is the upper object, calculating the positional relationship between the vehicle and the fixed target in the height direction based on a vertical detection angle of the fixed target that is detected by the radar sensor or a vertical detection angle range of the radar sensor and a front-rear distance of the fixed target at a timing that the fixed target is lost from the vertical detection angle range; and when the fixed target is the road object, increasing a degree of correction of the detected vehicle speed using the relative speed and the positional relationship compared to when the fixed target is the upper object.
6 . The method according to claim 5 , further comprising storing information on the received electric power of the radar sensor, wherein the determination of whether the fixed target is the road object or the upper object is based on the information on the received electric power stored within a period until the vehicle passes the fixed target or a period until the received electric power dissipates.
7 . The method according to claim 6 , wherein the determination that the fixed target is the upper object is made when: the front-rear distance of the fixed target at a timing that the received electric power has dissipated by an amount equal to or greater than a first predetermined value; a decrease rate of the received electric power with respect to the front-rear distance of the fixed target is equal to or greater than a second predetermined value; a decrease rate of the relative speed with respect to the front-rear distance of the fixed target is equal to or greater than a third predetermined value, and the fixed target is present within a right-left detection range of the radar sensor; and/or a right-left distance of the fixed target is equal to or less than a fourth predetermined value.
8 . The method according to claim 5 , wherein the radar sensor is a millimeter wave radar.
9 . A non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium including instructions that when executed by circuitry causes the circuitry to: determine whether a fixed target present in front of a vehicle is a road object or an upper object based on a received electric power of a radar sensor of the vehicle; calculate a detected vehicle speed of the vehicle based on a detection result of a wheel speed sensor of the vehicle; calculate a positional relationship between the vehicle and the fixed target based on a detection result of the radar sensor; calculate a relative speed of the vehicle based on the calculated positional relationship; and calculate a corrected vehicle speed by correcting the detected vehicle speed based on the relative speed of the fixed target with respect to the vehicle that is detected by the radar sensor and the positional relationship, wherein: when the fixed target is the road object, the calculation of the positional relationship between the vehicle and the fixed target in a height direction is based on an installation height of the radar sensor from a road surface; when the fixed target is the upper object, the calculation of the positional relationship between the vehicle and the fixed target in the height direction based on a vertical detection angle of the fixed target that is detected by the radar sensor or a vertical detection angle range of the radar sensor and a front-rear distance of the fixed target at a timing that the fixed target is lost from the vertical detection angle range; and when the fixed target is the road object, a degree of correction of the detected vehicle speed using the relative speed and the positional relationship compared to when the fixed target is the upper object is increased.
10 . The non-transitory computer-readable storage medium according to claim 9 , wherein the non-transitory computer-readable storage medium further includes instructions that when executed by the circuitry causes the circuitry to: store information on the received electric power of the radar sensor; and determine whether the fixed target is the road object or the upper object based on the information on the received electric power stored within a period until the vehicle passes the fixed target or a period until the received electric power dissipates.
11 . The non-transitory computer-readable storage medium according to claim 10 , wherein the non-transitory computer-readable storage medium further includes instructions that when executed by the circuitry causes the circuitry to determine that the fixed target is the upper object, when: the front-rear distance of the fixed target at a timing that the received electric power has dissipated by an amount equal to or greater than a first predetermined value; a decrease rate of the received electric power with respect to the front-rear distance of the fixed target is equal to or greater than a second predetermined value; a decrease rate of the relative speed with respect to the front-rear distance of the fixed target is equal to or greater than a third predetermined value, and the fixed target is present within a right-left detection range of the radar sensor; and/or a right-left distance of the fixed target is equal to or less than a fourth predetermined value.
12 . The non-transitory computer-readable storage medium according to claim 9 , wherein the radar sensor is a millimeter wave radar.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Japanese Patent Application No. 2023-014193 filed on Feb. 1, 2023, incorporated herein by reference in its entirety. BACKGROUND 1. Technical Field The present disclosure relates to a vehicle speed calculation device. 2. Description of Related Art Conventionally, Japanese Patent No. 6832166 (JP 6832166 B) is known as a technical document related to a vehicle speed calculation device. JP 6832166 B discloses a technique that corrects a detected own vehicle speed detected by a vehicle speed sensor using a relative speed of a target that is detected by a radar sensor. SUMMARY In the conventional technique as described above, angular resolution of the radar sensor in the vertical direction of a vehicle may be relatively rough. Therefore, for example, when the target is an upper object, as a result of deterioration in detection accuracy of a vertical detection angle of the target, there is a possibility that correction accuracy of a vehicle speed deteriorates. An object of the present disclosure is to provide a vehicle speed calculation device that enables to suppress deterioration in the correction accuracy of the vehicle speed. The vehicle speed calculation device of the present disclosure is a vehicle speed calculation device that calculates a vehicle speed of a vehicle, the vehicle speed calculation device including a target category determination unit that determines whether a fixed target present in front of the vehicle is an object on a road or an upper object, based on a received electric power of a radar sensor of the vehicle, a vehicle speed calculation unit that calculates a vehicle speed of the vehicle, based on a detection result of a wheel speed sensor of the vehicle, a positional relationship calculation unit that calculates a positional relationship between the vehicle and the fixed target, based on a detection result of the radar sensor, and a vehicle speed correction unit that corrects the vehicle speed, based on a relative speed of the fixed target with respect to the vehicle that is detected by the radar sensor and the positional relationship. The positional relationship calculation unit calculates, when the fixed target is an object on a road, the positional relationship between the vehicle and the fixed target in a height direction based on an installation height of the radar sensor from a road surface, and the positional relationship calculation unit calculates, when the fixed target is an upper object, the positional relationship between the vehicle and the fixed target in the height direction, based on a vertical detection angle of the fixed target that is detected by the radar sensor, or a vertical detection angle range of the radar sensor and a front-rear distance of the fixed target at timing that the fixed target is lost from the vertical detection angle range. The vehicle speed correction unit increases, when the fixed target is an object on a road, degree of correction of the vehicle speed using the relative speed and the positional relationship compared to when the fixed target is an upper object. According to the present disclosure, it is possible to provide a vehicle speed calculation device that is able to suppress deterioration in the correction accuracy of the vehicle speed. BRIEF DESCRIPTION OF THE DRAWINGS Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: FIG. 1 is a block diagram of a vehicle speed calculation device according to one embodiment; FIG. 2 is a plan view for explaining the positional relationship between the vehicle and the target; FIG. 3 is a side view for explaining the positional relationship between the vehicle and the target; FIG. 4 is a side view for explaining the positional relationship between the vehicle and the target; FIG. 5 is a diagram showing changes over time in received electric power of a radar sensor; and FIG. 6 is a flowchart showing processing by the vehicle speed calculation device shown in FIG. 1. DETAILED DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIG. 1 is a block diagram of a vehicle speed calculation device according to one embodiment. As shown in FIG. 1, the vehicle speed calculation device 1 includes a wheel speed sensor 2, a radar sensor 3, and an Electronic Control Unit (ECU) 10. A vehicle speed calculation device 1 calculates the vehicle speed of a vehicle 8 (see FIG. 2). The wheel speed sensor 2 is provided for a wheel, drive shaft, or the like of a vehicle 8 (see FIG. 2). The drive shaft rotates integrally with the wheel. The wheel speed sensor 2 detects the rotational speed of the wheels of the vehicle 8. The wheel speed sensor 2 transmits the detection result to the ECU 10. As shown in FIGS.