LEVEL AND SLOPE CONTROL FOR SURFACING MACHINES

• US 3,554,291 A
• Filed: 11/08/1967
• Issued: 01/12/1971
• Est. Priority Date: 11/08/1967
• Status: Expired due to Term

• Current Assignee: Rex C. Knapp, Richard E. Rogers
• Original Assignee: Rex C. Knapp, Richard E. Rogers
• Inventors: Rogers, Richard E., Knapp, Rex C.
• Application Number:
  US04/681,522
• Time in Patent Office: 1,161 Days
• US Class Current: 172/4.5
• CPC Class Codes: E02F 3/847 using electromagnetic, optical or acoustic beams to determine the blade position, e.g. laser beams

Abstract

A level and slope control for road graders and similar surfacing machines is described in which one or more very narrow electromagnetic beams are projected along the path to be graded, and photoelectric sensors on the grading machine are utilized to receive and detect positional information from the light beams and to generate correction signals which both adjust the position of the surfacing blade and steer the machine in the desired direction.

Claims

1. In a self-propelled surfacing machine having a chassis, ground engaging support means for said chassis, steering means for said support means, a ground engaging leveling element carried by said chassis, and power means connected between said chassis and said leveling element for adjusting the vertical position of said leveling element relative to said chassis;

an automatic control system for steering said machine along a predetermined path while maintaining said leveling element along a predetermined grade by following a collimated electromagnetic beam projected along said path and parallel to said grade by a remotely stationed transmitter;

said control system comprising the combination of;

a beam target mounted on said leveling element and having a target area that is large relative to the cross-sectional area of said beam, said target area including a central null region positioned to intercept said beam under nominal operating conditions, vertically spaced sensing regions responsive to impingement of said beam thereon for supplying a first control signal, and horizontally spaced sensing regions responsive to impingement of said beam thereon for generating a second control signal;

said vertically and horizontally spaced sensing regions having sensitivities which vary outwardly from said central null region so that said first and second control signals have magnitudes that are respectively proportional to the vertical and horizontal deviation of said beam from said central null region;

first control means coupled between said target and said power means and proportionally responsive to the magnitude of said first control signal for correctively actuating said power means to maintain said leveling element along said grade; and

second control means coupled between said target and said steering means and proportionally responsive to the magnitude of said second control signal for correctively actuating said steering means to steer said machine along said path.

2. In a self-propelled surfacing machine having a chassis, ground engaging support means for said chassis, steering means for said support means, a support structure pivotably mounted on said chassis for rotational movement about its own longitudinal axis and vertical movement relative to said chassis, a ground engaging leveling element pivotably mounted on said support structure for rotation about an axis perpendicular to the longitudinal axis of said support structure, first power means connected between said chassis and said leveling element for varying the vertical position of said leveling Element relative to said chassis, and second power means connected between said chassis and said leveling element for varying the angle of said leveling element transversely of said chassis;

an automatic control system for maintaining said leveling element along a predetermined grade with a predetermined slope by following a collimated electromagnetic beam projected along a predetermined path of travel for said machine and parallel to said grade by a remotely stationed transmitter;

said control system comprising the combination of;

a beam target mounted on said leveling element and having a target area which is large relative to the cross-sectional area of said beam, said target area including a null region positioned to intercept said beam under nominal operating conditions and vertically spaced sensing regions which are responsive to impingement of said beam thereon for supplying a first control signal;

first control means coupled between said target and said first power means for correctively actuating said first power means in response to said first control signal to thereby return said leveling element to said grade;

reference means mounted on said machine for providing a reference signal indicative of the predetermined slope for said leveling element;

detector means for supplying a second control signal indicative of the actual slope of said leveling element, said detector means including the series connected combination of a first gravity-operated potentiometer mounted on said support structure for providing a signal representative of the angle between said grade and true horizontal transversely of the machine, a second potentiometer coupled between said support structure and said chassis for operation in response to vertical movement of said support structure relative to said chassis for providing a signal representative of the angle between said leveling element and true horizontal longitudinally of said machine, and a third potentiometer coupled between said leveling element and said support structure for operation in response to rotation of said leveling element about said perpendicular axis for providing a signal representative of the rotational position of said leveling element; and

second control means coupled to said reference means, said detector means and said second power means for correctively actuating said second power means in response to an imbalance between said reference signal and said second control signal to thereby return said leveling element to said predetermined slope.

3. In a self-propelled surfacing machine having a chassis, ground engaging support means for said chassis, steering means for said support means, a ground engaging leveling element pivotably mounted on said chassis, first power means connected between said chassis and said leveling element for varying the vertical position of said leveling element relative to said chassis, and second power means connected between said chassis and said leveling element for varying the angle of said leveling element transversely of said chassis;

an automatic control system for maintaining said leveling element along a predetermined grade with a predetermined slope by following a collimated electromagnetic beam projected along a predetermined path of travel for said machine and parallel to said grade by a remotely stationed transmitter;

said control system comprising the combination of;

a beam target mounted on said leveling element and having a target area which is large relative to the cross-sectional area of said beam, said target area including a null region positioned to intercept said beam under nominal operating conditions, vertically spaced sensing regions which are responsive to impingement of said beam thereon for supplying a first control signal and a pair of horizontally spaced sensing regions one on either side of said null region for supplying a second control signal in response to the impingement of said beam on either of them;

first control meanS coupled between said target and said first power means for correctively actuating said first power means in response to said first control signal to thereby return said leveling element to said grade;

a second control means coupled between said target means and said steering means for correctively actuating said steering means in response to said second control signal to maintain said machine along said predetermined path of travel;

reference means mounted on said machine for providing a reference signal indicative of the predetermined slope for said leveling element;

detector means coupled to said leveling element for supplying a third control signal indicative of the actual slope of said leveling element; and

third control means coupled to said reference means, said detector means and said second power means for correctively actuating said second power means in response to an imbalance between said reference signal and said third control signal to thereby return said leveling element to said predetermined slope.

4. The combination of claim 3 wherein said leveling element is mounted on a support structure for rotation about an axis perpendicular to the longitudinal axis of said support structure, said support structure is pivotably mounted on said chassis for vertical movement relative to said chassis and for rotational movement about the longitudinal axis of said support structure;

and said detector means includes the series-connected combination of a first gravity-operated potentiometer mounted on said support structure for providing a signal representative of the angle between said leveling element and true horizontal transversely of the machine, a second potentiometer coupled between said support structure and said chassis for operation in response to vertical movement of said support structure relative to said chassis for providing a signal representative of the angle between said leveling element and true horizontal longitudinally of the machine, and a third potentiometer coupled between said leveling element and said support structure for operation in response to rotation of said leveling element about said perpendicular axis for providing a signal representative of the rotational position of said leveling element.