Ultrasonic sensor control unit for a road finishing machine

• US 5,258,961 A
• Filed: 11/13/1992
• Issued: 11/02/1993
• Est. Priority Date: 11/15/1991
• Status: Expired due to Term

• Current Assignee: Moba-Electronic Automation GmbH
• Original Assignee: Moba-Electronic Gesellschaft Fur Mobil-Automation MbH
• Inventors: Sehr, Willibald, Zarniko, Martin
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US07/975,710
• Time in Patent Office: 354 Days
• Field of Search: 367/95, 367/96, 367/124, 367/126, 367/13, 404/110, 404/84.5, 364/167.01, 364/474.34, 172/4.5
• US Class Current: 367/96
• CPC Class Codes: E01C 19/006 by laser or ultrasound
• CPC Class Codes: E02F 3/844 for positioning the blade, e.g. hydraulically
• CPC Class Codes: E02F 9/2025 Particular purposes of control systems not otherwise provided for E02F3/16, E02F3/26, sub-groups of E02F3/43, E02F3/651, sub-groups of E02F3/84, E02F3/907, E02F5/145 take precedence
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations

Abstract

An ultrasonic sensor control unit for a road finishing machine for generating a height control signal for a vertically adjustable beam, the ultrasonic sensor control unit including at least three ultrasonic sensors which are arranged at a considerable distance from the beam in the direction of motion of the road finishing machine. The ultrasonic sensor signals determine the distances between each ultrasonic sensor and a reference surface, the values which lie more than a predetermined distance outside of a plane which is determined by the measuring points associated with the other distances being rejected as faulty measurement. On the basis of the height signals, the mutual distances of the sensors, and the distance between a sensor and the rear edge of the beam, the evaluation means calculates the projected height at the rear edge of the beam. This height is compared with a selectable desired thickness value. The evaluation means controls the tie points of the beam so that an adequate layer thickness will be created.

Claims

1. An ultrasonic control unit for a road finishing machine for adjusting the height of a vertically adjustable screed of said machine with regard to a reference surface, comprising:

at least three ultrasonic sensors (10,11,12), each having a associated radiation cone, said ultrasonic sensors (10,11,12) being arranged on a holding device (5a) which is secured to the screed (4), in spaced relationship (a) with one another essentially in the direction of motion of the road finishing machine (1) in such a way that, on the reference surface, a distance exists between the individual radiation cones of said ultrasonic sensors (10, 11,

     12),

an evaluation means (15) for detecting the distances (s1, s2, s3) between each ultrasonic sensor (10, 11,

     12) and the reference surface on the basis of the ultrasonic sensor signals, said evaluation means (15) being adapted to reject one of the measured distances (s1, s2, s3) as faulty measurement, if the measuring point in question lies more than a predetermined distance outside of the plane which is determined by the measuring points associated with the other distances; and

means (15) being adapted for calculating the height of the read edge (9) of the screed relative to the reference surface on the basis of the distances (s1,s2,s3) which have not been rejected as faulty measurements and the known geometrical arrangement of the ultrasonic sensors (10, 11,

     12) with respect to said rear edge (9) of the screed (4).

2. An ultrasonic sensor control unit according to claim 1, wherein said screed is attached to a tie bar, said tie bar having a tie point, said tie bar being adapted to freely articulate about said tie point, and

said calculating means (15) being adapted to generate a height control signal for adjusting said tie point of said tie arm (5) relative to said road finishing machine.

3. An ultrasonic sensor control unit according to claim 1, wherein the calculation means (15) is adapted to derive form said height and from a selectable desired thickness of the road surfacing to be produced a height control signal for adjusting said screed (4).

4. An ultrasonic control unit for a road finishing machine for adjusting the height of a vertically adjustable screed of said machine with regard to a reference surface, comprising:

at least three ultrasonic sensors (10,11,12), each having a associated radiation cone, said ultrasonic sensors (10,11,12) being arranged on a holding device (5a) which is secured to the screed (4), in spaced relationship (a) with one another essentially in the direction of motion of the road finishing machine (1) in such a way that, on the reference surface, a distance exists between the individual radiation cones of said ultrasonic sensors (10, 11,

     12), said ultrasonic sensors (10, 11,

     12) being attached to said holding device (5a) on a respective known level and at known distances from one another

an evaluation means (15) for detecting the distances (s1, s2, s3) between each ultrasonic sensor (10, 11,

     12) and the reference surface on the basis of the ultrasonic sensor signals, said evaluation means (15) being adapted to determine the differences (d12, d13, d14) between respective two distances (s1, s2;

s1, s3;

s2, s3), and to classify the distances whose difference is smaller than a limit value as valid distances, and

means (15) adapted for calculating the height of the rear edge (9) of the screed (4) relative to the reference surface on the basis of the valid distance (s1, s2, s3) and the known geometrical arrangement of the ultrasonic sensors (10, 11,

     12) with respect to said rear edge (9) of the screed (4).

5. An ultrasonic sensor control unit according to claim 4, wherein the calculating means (15) is adapted to derive from said height and from a selectable desired thickness of the road surfacing to be produced a height control signal for adjusting said screed (4).

6. An ultrasonic sensor control unit according to claim 4, wherein said screed is attached to a tie bar, said tie bar having a tie point, said tie bar being adapted to freely articulate about said tie point, and

said calculating means (15) being adapted to generate a height control signal for adjusting said tie point of said tie arm (5) relative to said road finishing machine.