Method and system for compensation of ultrasonic sensor

• US 8,656,781 B2
• Filed: 10/18/2010
• Issued: 02/25/2014
• Est. Priority Date: 10/18/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Lavoie, Erick Michael
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): MILLER, ROSE MARY
• Application Number:
  US12/907,019
• Publication Number:
  US 20120090395A1
• Time in Patent Office: 1,226 Days
• Field of Search: 73/18.2, 736/02, 367/118, 367/902, 367/909
• US Class Current: 73/602
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 2015/938 in the bumper area
• CPC Class Codes: G01S 7/52006 with provision for compensating the effects of temperature

Abstract

A system and method for compensating ultrasonic sensors mounted on a vehicle for speed of sound variations. The ultrasonic sensor is operatively coupled to a power train control module having a pressure sensor that continuously monitors atmospheric pressure and a controller configured for computing a compensated speed of sound using the monitored atmospheric pressure. The ultrasonic sensor sends an ultrasonic wave and determines the time lag in receiving the reflected ultrasonic wave from an object. Subsequently, the ultrasonic sensor generates a signal corresponding to the relative distance between the vehicle and the object using the compensated speed of sound and the time lag.

Claims

1. A system compensating ultrasonic sensors mounted on a vehicle for speed of sound variations, the system comprising:

a power train control module including;

a pressure sensor configured for monitoring atmospheric pressure; and

a controller configured for computing a compensated speed of sound using the monitored atmospheric pressure to compensate for atmospheric variations;

an ultrasonic sensor operatively coupled to the power train control module, the ultrasonic sensor being configured for;

transmitting an ultrasonic wave;

determining the time lag in receiving the reflected ultrasonic wave from an object;

receiving the compensated speed of sound corresponding to the ultrasonic wave;

generating an output signal corresponding to the relative distance between the vehicle and the object using the compensated speed of sound and the time lag; and

a parking assist module, operating at least in part based on the output of the ultrasonic sensor and the relative distance between the vehicle and the object.

2. The system of claim 1, wherein the pressure sensor continuously monitors the atmospheric pressure.

3. The system of claim 1, wherein the power train control module further includes an ambient temperature sensor to compensate for temperature variations on the speed of sound.

4. The system of claim 3, wherein the ambient temperature sensor is employed in case the pressure sensor is non-operational.

5. A method for compensating an ultrasonic sensor mounted on a vehicle for atmospheric pressure variations, the method comprising:

providing a power train control module having a pressure sensor;

monitoring atmospheric pressure using the pressure sensor;

transmitting an ultrasonic wave from the ultrasonic sensor;

determining the time lag in receiving the reflected ultrasonic wave from the object;

computing a compensated speed of sound based on the monitored atmospheric pressure;

generating an output signal corresponding to the relative distance between the vehicle and the object using the compensated speed of sound and the time lag; and

assisting in parking the vehicle, employing a parking assist module operating at least in part based on the output signal corresponding to the relative distance between the vehicle and the object.

6. The method of claim 5, wherein the monitoring step involves continuously monitoring the atmospheric pressure.

7. The method of claim 5, wherein the computing step uses the pressure sensor output monitored within the time lag.

8. The method of claim 7, wherein the compensated speed compensates for variation in the speed of sound due to atmospheric pressure variations.