INCLINATION DETECTOR AND ONBOARD APPARATUS

• US 20150088455A1
• Filed: 08/01/2012
• Published: 03/26/2015
• Est. Priority Date: 08/01/2012
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Yamashita, Toshiyuki
• Granted Patent: US 10,001,361 B2
• Time in Patent Office: Days
• US Class Current: 702/155
• CPC Class Codes: B60Q 1/115 by electric means details of the electric drive components, e.g. motors, shafts, ball joints B60Q1/076
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01C 9/08 Means for compensating acceleration forces due to movement of instrument
• CPC Class Codes: G01P 15/14 by making use of gyroscopes gyroscopes per se G01C19/00
• CPC Class Codes: G01P 15/16 by evaluating the time-derivative of a measured speed signal

Abstract

A real acceleration computing unit 3 calculates the real acceleration Gw in the direction of travel of a vehicle by acquiring the velocity V a wheel speed sensor 12 installed in the vehicle detects. A road surface gradient computing unit 5 calculates the inclination of a road surface (road surface gradient θ1) from the real acceleration Gw and the accelerations Gx and Gz in the back and forth and up and down directions of the vehicle an acceleration sensor 11 installed in the vehicle detects. A pitching angle computing unit 6 calculates the inclination of the vehicle with respect to the road surface (pitching angle θ2) from the real acceleration Gw and the accelerations Gx and Gz.

Claims

1. An inclination detector comprising:

an inclination computing unit that calculates one of or both of a road surface gradient and a pitching angle from acceleration in back and forth direction and acceleration in up and down direction of a vehicle and from real acceleration in direction of travel of the vehicle, the road surface gradient being an inclination in back and forth direction of a road surface on which the vehicle is placed, and the pitching angle being an inclination in the back and forth direction of the vehicle with respect to the road surface.

2. The inclination detector according to claim 1, further comprising:

a communication interface that acquires velocity in the direction of travel from a wheel speed sensor installed in the vehicle; and

a real acceleration computing unit that calculates the real acceleration in the direction of travel by differentiating the velocity acquired via the communication interface.

3. The inclination detector according to claim 1, further comprising:

a communication interface that acquires acceleration in any two-axis directions from a two-axis acceleration sensor installed in the vehicle, the two-axis acceleration sensor being installed in a state in which at least one axis has a tilt with respect to a horizontal plane passing through the back and forth direction and right and left direction of the vehicle and with respect to a vertical plane passing through the right and left direction and up and down direction of the vehicle; and

an acceleration converter that converts accelerations in the any two-axis directions acquired via the communication interface to acceleration in the back and forth direction and to acceleration in the up and down direction by using mounting information of the two-axis acceleration sensor.

4. The inclination detector according to claim 1, further comprising:

a communication interface that acquires acceleration in the back and forth direction and acceleration in the up and down direction from a two-axis acceleration sensor which is installed in the vehicle in a state in which a first axis is parallel to the back and forth direction of the vehicle, and a second axis is parallel to the up and down direction of the vehicle.

5. The inclination detector according to claim 1, further comprising:

a two-axis acceleration sensor that is installed in the vehicle in a state in which a first axis is parallel to the back and forth direction of the vehicle and a second axis is parallel to the up and down direction of the vehicle, and that detects acceleration in the back and forth direction and acceleration in the up and down direction.

6. The inclination detector according to claim 1, wherein

the inclination computing unit that calculates or approximately calculates the following two expressions using acceleration Gx in the back and forth direction, acceleration Gz in the up and down direction and the real acceleration Gw in the direction of travel, and calculates one of or both of the road surface gradient θ

1 and the pitching angle θ

2,

Gx=Gw cos θ

2−

g sin(θ

1+θ

2)

Gz=−

Gw sin θ

2−

g cos(θ

1+θ

2)

where g is gravitational acceleration.

7. The inclination detector according to claim 1, wherein

the inclination computing unit holds the road surface gradient θ

1 while the vehicle is stopped, and calculates or approximately calculates the following two expressions using the acceleration Gx in the back and forth direction or the acceleration Gz in the up and down direction to calculate the pitching angle θ

2,

Gx=−

g sin(θ

1+θ

2) or Gz=−

g cos(θ

1+θ

2)

where g is gravitational acceleration.

8. The inclination detector according to claim 3, further comprising:

a sensitivity correcting unit that corrects, while the vehicle is stopped and when difference between the gravitational acceleration and components of a vector of the acceleration in the back and forth direction and of a vector of the acceleration in the up and down direction is greater than a prescribed first threshold, sensitivity of the two-axis acceleration sensor in accordance with the individual accelerations and the gravitational acceleration.

9. The inclination detector according to claim 8, wherein

the sensitivity correcting unit sends information to the inclination computing unit if the difference between the gravitational acceleration and the components of the vector of the acceleration in the back and forth direction and of the vector of the acceleration in the up and down direction is greater than a prescribed second threshold that is greater than the first threshold;

and

the inclination computing unit substitutes a preset value for one of or both of the road surface gradient and the pitching angle when receiving the information from the sensitivity correcting unit.

10. An onboard apparatus operating on a basis of one of or both of the road surface gradient and the pitching angle the inclination detector as defined in claim 1 calculates.