Environment monitoring system for a vehicle

• US 9,459,347 B2
• Filed: 07/30/2011
• Issued: 10/04/2016
• Est. Priority Date: 09/17/2010
• Status: Active Grant

• Current Assignee: ZF CV Systems Europe BV
• Original Assignee: Wabco GmbH (Wabco Holdings Incorporated)
• Inventors: Lucking, Christoph, Risse, Rainer, Ronnenberg, Udo, Stender, Axel
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US13/821,750
• Publication Number:
  US 20130162461A1
• Time in Patent Office: 1,893 Days
• Field of Search: 342/70, 342/118, 342/146
• US Class Current: 1/1
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 15/878 wherein transceivers are operated, either sequentially or simultaneously, both in bi-static and in mono-static mode, e.g. cross-echo mode
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2015/938 in the bumper area radar in bumper area G01S2013/93275; bumper with obstacle sensor of electric or electronic type B60R19/483

Abstract

An environment monitoring system for a vehicle includes at least two distance sensors for detecting distance by measuring the propagation time of detection signals. The distance sensors are each designed as a transmitting unit and receiving unit for the detection signals and, in a direct operating mode, emit detection signals, receive reflected components of the detection signals emitted by the distance sensors; and emit active measurement signals according thereto. The system also includes a control device that receives the measurement signals of the distance sensors and determines the object distance of a detected object. At least one distance sensor additionally can be operated in an indirect operating mode to detect a detection signal emitted by another distance sensor and reflected by the object and to generate an indirect measurement signal.

Claims

1. An environment monitoring system for a vehicle, the monitoring system comprising:

at least two distance sensors configured to;

(i) output detection signals and receive reflected components of the detection signals, and (ii) detect distances to an object by measuring a propagation time of the detection signals, wherein, in a triangulation mode of the monitoring system, the at least two distance sensors are simultaneously operated in a direct operating mode such that each of the at least two sensors generates an active measurement signal based on propagation time of a detection signal output by that distance sensor and a reflected component thereof, and wherein, in a combined operating mode of the monitoring system, one of the at least two distance sensors is operated in the direct operating mode and each of the others of the at least two distance sensors is operated in an indirect operating mode to passively receive a reflected component of a detection signal output by the one distance sensor of the at least two distance sensors operable in the direct operating mode and reflected by the detected object, and to generate an indirect measurement signal based thereon; and

a control device configured to receive the active and indirect measurement signals from the at least two distance sensors and to determine an object distance of the detected object.

2. The monitoring system according to claim 1, wherein the system is a rear area monitoring system arranged in a rear region of the vehicle to determine the object distance of the detected object when the detected object is located in a rear area behind the vehicle.

3. The monitoring system according to claim 1, wherein the detection signals are one of ultrasonic waves and radar waves and light beams output by the at least two distance sensors into emission angle regions.

4. The monitoring system according to claim 3, wherein the emission angle regions of the at least two distance sensors are directed rearwards and towards one another so as to at least largely overlap in a rear area behind the vehicle.

5. The monitoring system according to claim 3, wherein the emission angle regions of the at least two distance sensors are substantially in a horizontal plane and detect an angle range of greater than about 45 degrees.

6. The monitoring system according to claim 1, wherein each of the at least two distance sensors is operable in:

a) the direct operating mode to determine a distance between that distance sensor and the object as half the distance covered by a detection signal output by that distance sensor in a detection time between an emission time of that detection signal and a receiving time of a reflected component thereof, and

b) the indirect operating mode to determine in an indirect measurement a sum of a distance between that distance sensor and the object and a distance between a transmitting one of the at least two distance sensors and the object, that distance sensor and the transmitting distance sensor being synchronized when that distance sensor is in the indirect operating mode such that an emission time of a detection signal output by the transmitting distance sensor and a receiving time of a reflected component thereof is aligned, the distance between that distance sensor and the object being determinable by the control device by subtracting the distance between the transmitting distance sensor and the object, determined in an active measurement signal generated by the transmitting distance sensor, from the sum determined in the indirect measurement.

7. The monitoring system according to claim 1, wherein, in the combined operating mode, each of the other distance sensors is restricted from transmitting detection signals.

8. The monitoring system according to claim 1, wherein, in the combined operating mode, the at least two distance sensors are configured to alternate their operating modes, such that different ones of the at least two distance sensors are operable in the direct operating mode.

9. The monitoring system according to claim 1, wherein the at least two distance sensors are operable in at least one of the following further operating modes:

a) a radius estimation mode when only a single one of the at least two distance sensors receives a reflected detection signal in a direct measurement;

b) a back-up operating mode in which some or all of the at least two distance sensors substantially simultaneously transmit and receive to increase emitted total signal power and to estimate the object distance; and

c) an exclusively indirect measurement mode when there are only indirect measurements by determining the object distance on an ellipse that forms a set of all points with the same sum of distances to the at least two distance sensors.

10. The monitoring system according to claim 1, wherein the control device is configured to output synchronization signals to all of the at least two distance sensors to synchronize the at least two distance sensors.

11. The monitoring system according to claim 1, wherein the control device is connected to the at least two distance sensors via a bus, and is configured to output synchronization signals for the combined operating mode, the synchronization signals being addressed to all of the at least two distance sensors and containing, as a parameter, a statement as to which of the at least two distance sensors is to be the one distance sensor that operates in the direct operating mode.

12. The monitoring system according to claim 1, wherein the at least two distance sensors comprise two distance sensors disposed at left-hand and right-hand lateral rear regions of the vehicle.

13. The monitoring system according to claim 1, wherein the at least two distance sensors comprise three distance sensors, one of which is disposed at a left-hand lateral rear region of the vehicle, one of which is disposed at a right-hand lateral rear region of the vehicle, and one of which is disposed at a middle rear region of the vehicle.

14. The monitoring system according to claim 1, wherein the at least two distance sensors are in a plurality of planes positioned above one another.

16. The monitoring system according to claim 11, wherein the bus is a LIN bus.

17. The monitoring system according to claim 1, wherein the control device is configured, in the triangulation operating mode, to determine the object distance based on a known distance between the at least two distance sensors.

18. The monitoring system according to claim 1, wherein the control device is further configured to change the operating mode from the combined operating mode to the triangulation operating mode, when no indirect measurement signals are received in the combined operating mode.

15. A method for determining distance to an object using an environment monitoring system, the environment monitoring system comprising a control device and at least two distance sensors configured to (i) output detection signals and receive reflected components thereof and (ii) detect distances to an object by measuring a propagation time of the detection signals, the method comprising:

in a triangulation mode of the monitoring system;

controlling the at least two distance sensors to simultaneously operates in a direct operating mode such that each of the at least two sensors generates an active measurement signal based on propagation time of a detection signal output by that distance sensor and a reflected component thereof; and

determining, using the control device, an object distance of the detected object based on the active measurement signals; and

in a combined operating mode of the monitoring system;

controlling the at least two distance sensors such that one of the at least two distance sensors operates in the direct operating mode and each of the others of the at least two distance sensors operates in an indirect operating mode to passively receive a reflected component of a detection signal output by the one distance sensor of the at least two distance sensors operating in the direct operating mode and reflected by the detected object, and to generate an indirect measurement signal based thereon; and

determining, using the control device, an object distance of the detected object based on an active measurement signal generated by the one distance sensor of the at least two distance sensors and the indirect measurement signal generated by each of the other distance sensors of the at least two distance sensors.