Inclination angle measurement apparatus

• US 20030154792A1
• Filed: 02/06/2003
• Published: 08/21/2003
• Est. Priority Date: 02/15/2002
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Katayama, Yoshio
• Granted Patent: US 7,000,476 B2
• Time in Patent Office: Days
• US Class Current: 73/602
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: G01C 9/00 Measuring inclination, e.g. by clinometers, by levels
• CPC Class Codes: G01S 15/872 Combination of several systems for attitude determination using inertial means G01C9/00, control of attitude G05D1/49

Abstract

An inclination angle measurement apparatus includes a first ultrasonic sensor (3) for sending an ultrasonic wave toward a reflective object (2), second and third ultrasonic sensors (4 and 5) each for receiving an ultrasonic wave reflected from the reflective object (2), and a calculation control circuit (14) for calculating an angle of inclination of a moving object with respect to the reflective object (2) based on a phase difference between ultrasonic waves received by the second and third ultrasonic sensors (4 and 5). Thus the inclination angle measurement apparatus can accurately measure the angle of inclination of the moving object with respect to the reflective object (2).

Claims

1. An inclination angle measurement apparatus comprising:

a sending/receiving means for sending a wave toward a reflective object and for receiving two waves reflected from said reflective object; and

an inclination angle calculating means for calculating an angle of inclination of a moving object with respect to said reflective object based on a phase difference between phases of the two reflected waves.

2. The inclination angle measurement apparatus according to claim 1, wherein said wave sent by said sending/receiving means is an ultrasonic wave, and said two reflected waves are two ultrasonic waves reflected from said reflective object.

3. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means includes a first ultrasonic sensor for sending an ultrasonic wave toward said reflective object and second and third ultrasonic sensors disposed at an equal distance from said first ultrasonic sensor, for receiving two ultrasonic waves reflected from said reflective object, respectively, and said inclination angle calculating means calculates the angle of inclination of said moving object with respect to said reflective object based on a phase difference between the phases of the two reflected waves received by said second and third ultrasonic sensors.

4. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means includes a first ultrasonic sensor for sending an ultrasonic wave toward said reflective object and second and third ultrasonic sensors disposed at an equal distance from said first ultrasonic sensor, each for sending an ultrasonic wave toward said reflective object and then receiving an ultrasonic wave reflected from said reflective object, and said inclination angle calculating means determines a phase difference (referred to as a first phase difference from here on) between phases of two ultrasonic waves sent by said first ultrasonic sensor and received by said second and third ultrasonic sensors, also determines a phase difference (referred to as a second phase difference from here on) between a phase of an ultrasonic wave sent by said second ultrasonic sensor and received by said third ultrasonic sensor and a phase of an ultrasonic wave sent by said third ultrasonic sensor and received by said second ultrasonic sensor, and calculates the angle of inclination of said moving object with respect to said reflective object according to a phase difference that is obtained by correcting the first phase difference using the second phase difference.

5. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means includes a first ultrasonic sensor for sending an ultrasonic wave toward said reflective object and then receiving an ultrasonic wave reflected from said reflective object, and a second ultrasonic sensor disposed at a distance from said first ultrasonic sensor that is much smaller than a distance to said reflective object, for sending an ultrasonic wave in phase with the ultrasonic wave sent by said first ultrasonic sensor toward said reflective object and then receiving an ultrasonic wave reflected from said reflective object, and said inclination angle calculating means calculates the angle of inclination of said moving object with respect to said reflective object based on a phase difference between phases of the two reflected ultrasonic waves received by said first and second ultrasonic sensors.

6. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means includes first and second ultrasonic sensors each for sending an ultrasonic wave toward said reflective object, a third ultrasonic sensor for receiving the ultrasonic wave sent by said first ultrasonic sensor and reflected from said reflective object, a fourth ultrasonic sensor disposed at a distance from said second ultrasonic sensor that is equal to a distance between said first and third ultrasonic sensors, for receiving the ultrasonic wave sent by said second ultrasonic sensor and reflected from said reflective object, and said inclination angle calculating means calculates the angle of inclination of said moving object with respect to said reflective object based on a phase difference between phases of the two reflected ultrasonic waves received by said third and fourth ultrasonic sensors.

7. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means includes a first ultrasonic sensor for sending an ultrasonic wave toward said reflective object and then receiving an ultrasonic wave reflected from said reflective object and a second ultrasonic sensor for sending an ultrasonic wave toward said reflective object and then receiving an ultrasonic wave reflected from said reflective object, and said inclination angle calculating means calculates the angle of inclination of said moving object with respect to said reflective object based on a phase difference between phases of the two reflected ultrasonic waves received by said first and second ultrasonic sensors.

8. The inclination angle measurement apparatus according to claim 2, further comprising an amplitude detecting means for detecting an amplitude of each ultrasonic wave received by said sending/receiving means, and said inclination angle calculating means adjusts an amplitude of an ultrasonic wave that is sent toward said reflective object by said sending/receiving means so that the amplitude of each ultrasonic wave received by said sending/receiving means and detected by said amplitude detecting means falls within a predetermined range.

9. The inclination angle measurement apparatus according to claim 2, wherein said inclination angle calculating means determines a time that elapses until said sending/receiving means receives an ultrasonic wave reflected from said reflective object after sending an ultrasonic wave toward said reflective object and adjusts a number of pulses included in the ultrasonic wave that is sent toward said reflective object by said sending/receiving means according to the time determined thereby.

10. The inclination angle measurement apparatus according to claim 2, further comprising an amplitude detecting means for detecting an amplitude of each ultrasonic wave received by said sending/receiving means, and said inclination angle calculating means adjusts a number of pulses included in each ultrasonic wave that is sent toward said reflective object by said sending/receiving means so that a reverberation caused by direct reception of each ultrasonic wave sent by said sending/receiving means has a certain amplitude or less, which is detected by said amplitude detection means.

11. The inclination angle measurement apparatus according to claim 2, wherein said inclination angle calculating means determines a time that elapses until said sending/receiving means receives an ultrasonic wave reflected from said reflective object after sending an ultrasonic wave toward said reflective object and adjusts an amplitude of each ultrasonic wave that is sent toward said reflective object by said sending/receiving means and a number of pulses included in each ultrasonic wave that is sent toward said reflective object by said sending/receiving means according to the time determined thereby.

12. The inclination angle measurement apparatus according to claim 2, wherein each ultrasonic wave that is sent toward said reflective object by said sending/receiving means has a frequency of about 20 kHz.

13. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means includes a means for switching between two or more different frequencies for each ultrasonic wave that is sent toward said reflective object thereby when each received ultrasonic wave has a small amplitude.

14. The inclination angle measurement apparatus according to claim 2, wherein said sending/receiving means intermittently sends each ultrasonic wave toward said reflective object.

15. The inclination angle measurement apparatus according to claim 2, further comprising a flip-flop having a data terminal for receiving an electric signal acquired from one received ultrasonic wave, a clock terminal for receiving an electric signal acquired from another received ultrasonic wave, and an output terminal for outputting a signal representing a direction in which said inclination angle measurement apparatus is inclined.

16. The inclination angle measurement apparatus according to claim 1, wherein said sending/receiving means repeatedly performs a series of processes for sending a wave toward said reflective object and receiving two waves reflected from said reflective object two or more times, and said inclination angle calculating means determines the phase difference between the phases of the two reflected waves two or more times and calculates the angle of inclination of said moving object with respect to said reflective object from an average of two or more values of the phase difference which are determined thereby.

17. The inclination angle measurement apparatus according to claim 1, wherein said apparatus further comprises a means for enabling said inclination angle measurement apparatus while said moving object is traveling at a speed that falls within a predetermined range.

18. The inclination angle measurement apparatus according to claim 3, wherein said plurality of ultrasonic sensors are arranged along a length of said moving object.

19. The inclination angle measurement apparatus according to claim 3, wherein said plurality of ultrasonic sensors are arranged along a width of said moving object.

20. The inclination angle measurement apparatus according to claim 1, wherein said wave sent by said sending/receiving means is an electric wave, and said two reflected waves are two electric waves reflected from said reflective object.

21. The inclination angle measurement apparatus according to claim 1, wherein said wave sent by said sending/receiving means is a lightwave, and said two reflected waves are lightwaves reflected from said reflective object.

22. An inclination angle measurement apparatus comprising:

a plurality of inclination angle measurement means disposed at different locations of a moving object, each of said plurality of inclination angle measurement means including a sending/receiving means for sending a wave toward a reflective object and for receiving two waves reflected from said reflective object, and an inclination angle calculating means for calculating an angle of inclination of said moving object with respect to said reflective object based on a phase difference between phases of the two reflected waves; and

a means for calculating an average of angles of inclination of said moving object calculated by said plurality of inclination angle measurement means.