Ground Profile Reader

Abstract

An elongated beam having spaced apart ground engaging members supporting it on a monitored surface includes transport system for moving it normal to its longitudinal axis whereby a level transducer centrally attached to the beam and connected by powered electrical circuits to an indicator will continuously reflect the displacement (slope) of its ground engaging members on the monitored surface normal to the path transversed by the beam. The transport system may include a device for measuring the distance traversed and the indicator may include a strip chart recorder whereby a chart profile of the monitored surface can be obtained. Special marking devices can be operated by the circuits to physically mark or paint areas where the monitored surface is cut outside the prescribed tolerances with respect to slope.

Description

BACKGROUND OF THE INVENTION

Commercial application of automatic blade control systems for motorgraders, such as disclosed in U.S. Pat. No. 3,486,564 issued to Page et al. and U.S. Pat. No. 3,495,663 issued to Scholl et al., and also assigned to the assignee of this invention, have substantially improved the efficiency and productivity of finished grading with such earthmoving motorgraders. Such controls eliminate many of the tedious and difficult manual operator functions performed in the past and cut graded surfaces to a high degree of accuracy. However, miscalibration and/or environmental conditions may sometimes cause the graded surfaces to cut with such automatic machines to deviate from the prescribed tolerances, which deviations are often revealed by the numerous cross checks conducted by surveying techniques.

Environmental conditions which sometimes cause the loss of accuracy are soft or muddy soils that induce movements in the machine not readily compensated for by the automatic controls or extremely hard surfaces which load the machine in a manner that distortion in the frame will allow deviation between the automated system and the actual blade cut.

Normally the errors introduced by environmental conditions will be small, but outside the tolerances of .+-.1/8 inch per 10 linear feet often required in grading operation. Such small errors are difficult for an operator to detect and thus often go unnoticed.

When several spot checks reveal errors outside the allowable tolerances, the whole surface is often unnecessarily regraded with the automatic machine when spot grading in a few areas would suffice because the majority of the surface is within the allowable tolerances.

Thus, if the grader surface is read, and preferably marked, spot regrading is possible with a great savings in time and expense, with corresponding increases in efficiency. Also any miscalibration of an automated grader will be quickly detected.

As a result it is an object of this invention to provide a ground profile reader capable of accurately checking a graded surface with respect to slope.

Another object is the provision of a ground profile reader which can quickly check graded surfaces more accurately than infrequent spot checks.

Also, an object of the invention is to provide a reader which can provide a permanent record of the slope of a graded surface.

SUMMARY OF THE INVENTION

The above objects are accomplished by a ground profile reader having an elongated beam supported from a surface to be monitored by spaced apart ground engaging members, a transport system for moving the elongated beam normal to its longitudinal axis along the surface to be monitored and a level sensing transducer connected to the beam operable to generate an electrical signal proportional to the relative displacement of the ground engaging members relative to a horizontal plane with circuit means to convert it to an indication of the slope normal to the path traversed by the reader. The circuit means connected to the transducer may have a warning or marking device or both and certain embodiments may have mechanisms on the transport system for recording the distance traversed along with a recorder so an accurate strip profile of slope of the surface monitored can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan of the ground profile reader being towed by a motor grader blade to read the surface cut by the blade;

FIG. 2 is a rear elevation of an alternate embodiment using ski-type shoes or skids with the transport system formed by a hitch which is connected to a truck;

FIG. 3 is a more sophisticated embodiment of the ground profile reader in an exploded view; and

FIG. 4 is a circuit schematic of the embodiment shown in FIG. 3.

DESCRIPTION

As shown in FIG. 1 the ground profile reader 10 includes a frame 11, shown in a triangular configuration, that has a transverse rear axle 12 with wheels 13 mounted at its opposite ends and forwardly disposed caster or dirigible wheel 14 connected in a fork 15 that is pivoted on the forward end or apex of the frame. These wheels, which support the frame above the ground, preferably have hard rubber tread surfaces whereby their triangular disposition will cause the frame to position to match their disposition on a graded surface, without error due to wheel tread deflection as will likely occur with pneumatic or semi-pneumatic wheels. On the projecting ends of the axle 15 from fork 16 that supports wheel 14 therein, a bifurcated tongue 17 can be attached through which the machine can be pulled or pushed by hand or a vehicle. As can be appreciated from the drawings, as the reader is pulled through its transport system, the axle 12 will be substantially transverse to its direction of travel and therefore the rear of frame 11 rigidly connected to the to the axle will accurately reflect the slope between the points of contact of the rear wheels 13. Obviously, the frame itself can serve as part of the axle 12 if desired and the arrangement of a single dirigible wheel 14 forward of the rear axle will allow the frame to freely rotate about a longitudinal axis normal to the rear axle.

By mounting a calibrating plate 25 on the rear of the frame 11 so it is oriented parallel with the rear axle it can be employed to mount a pendulum type transducer 26 so that the transducer will measure the slope between the points of contact of the rear wheels. In mounting the transducer care is exercised to keep the swing axis of the pendulum normal to the rear axle. A commercially available level sensor or transducer, such as a Moog Mobile Level Sensor Model 86-121 manufactured by MOOG Industrial Division, can be employed. Such a transducer can provide a linear changing resistance for input angles of .+-. 10.degree. from horizontal with resolution of .+-. 10 arc seconds. A simple pendulum could also be used to drive a potentiometer as long as sufficient dampening was provided, as is available in the commercial unit discussed above.

The relationship of the forward end of the frame that forms the transport system relative to the elevation of rear wheels is not critical, as long as the frame is reasonably level along its longitudinal axis so as not to introduce significant error into the pendulum unit. If a steep grade is involved it may be desirable to move the front end of the frame up or down on the pivot of the caster or dirigible wheel 14 to improve the accuracy of the reader.

To increase the flexibility of the reader the rear axle 12 can be arranged to telescope so the rear wheels 13 can be extended to the positions indicated by the broken lines in FIG. 1 or to intermediate positions so they will not travel in the tire depressions that could cause error.

In operation the transducer is connected to an instrument box 27 on the frame through an electrical cable. Power is provided from a battery box 28 connected to the instrument box. An audible warning box 29 is also connected to the instrument box and when the slope deviates from acceptable error, as measured by pendulum transducer it will sound the appropriate warning. The details of the circuitry will be discussed subsequently but it can be appreciated that when the reader is pulled through its tongue 17, such as behind a motor grader blade A, it can independently monitor the slope being cut by the blade.

A simplified version of the ground profile reader 10 is illustrated in FIG. 2 wherein the forward caster or dirigible wheel 14 is removed and replaced by a socket 30 of a trailer hitch so the forward end of its triangular frame 11' is supported on a ball on the back of a vehicle B to form the transport system. The frame is smaller since the battery of the vehicle can be used to supply the power through electrical cable 31 for the instrument box 27 mounted thereon. Instead of rear wheels, ski-type shoes 32 are employed on the outboard ends of its axle 12' as shown. The same mounting plate 25 is employed to mount the pendulum transducer 26 and it can be seen that employment of an arcuate slot 33 therein can be used to increase the range of the transducer or alternatively set it at the desired slope so the pendulum transducer will indicate true horizontal when the ski-type shoes rest on a graded surface having the proper slope. Bolts 34 can be tightened when the pointer 35 reads the proper scribe mark. The output from the instrument box can be sent to the cab of the vehicle B via coaxial cable 36.

In FIG. 3, an exploded view is shown of a complete self-contained ground profile reader 10 incorporating automatic marking of the grade where the slope error exceeds allowable limits. Its triangular frame 40 is similar to the frame previously described but includes two mounting legs 41 for the rear wheels 42 whose axles are coaxially aligned so they function as a rigid axle. One axle is formed by the shaft of a tachgenerator 43 whereby the continuous slope readings can be associated with selected portions graded on a strip chart, as hereinafter described. The front end of the frame is supported on a fork 44 pivoted therein, with a wheel 45 journalled in the fork so its axle 46 protrudes on opposite sides thereof. A tongue 47 has a bifurcated end journalled on the projecting ends of the axle whereby the frame can be pulled or pushed through the tongue and steered.

On the central rear portion of the frame 40 a mounting flange secures a stub shaft 50 with a vertical shaft 51 disposed in an aperture and locked by a set screw 52. A horizontal yoke 53 which can move vertical on shaft 51 is centrally journalled in a beam 54 so its outboard ends 55 can oscillate about the longitudinal axis of the yoke. On the outboard ends of the beam, which is disposed parallel to the axles of the rear wheel 42, ski-type shoes are used to support the ends of the beam. The above arrangements allow the weight of the beam to be minimized whereby it tracks truly on soft graded surfaces, since the weight of the frame, components and wheels will not be transmitted to the ski-type shoes.

In the central portion of beam 54 the pendulum transducer 26 is mounted in an arcuate groove 57 and locked with bolts 34. In turn the transducer is connected to the instrument box 27 on the frame with an electrical cable, as is the tachgenerator 43. Power is supplied from a battery box 28 connected to the instrument box. An audio warning unit 29 is also connected to the instrument box. In addition the frame 40 has a marker unit 58 connected to a pneumatic reservoir 59 which can be actuated to spray paint through tubes 60 and 61, such as white paint for errors above the desired slope and red paint for errors below the desired slope. A strip chart recorder 62 is also connected to the instrument box.

More specifically the complete circuitry for the latter described embodiment of the ground profile reader is shown in FIG. 4 and some of the basic parts thereof will be common to all the readers described. Basically the battery box 28 includes a voltage divider network 70 so it can supply plus and minus voltages with respect to ground 71. Leads 72 and 73 connect the output of the voltage divider network to the pendulum transducer 26 which generates a linear output on lead 74 proportional to the angle from horizontal at which its case is disposed, which output is connected to the input of operational amplifier 75. The RC network on the amplifier feedback provides necessary filtering. This amplified output can be used to drive the strip chart recorder 62, a direct reading slope meter 76 and/or the audible warning unit 29 by connecting output lead 77 to these circuits. Depending on the position of the transducer on the mounting plate the circuits can be set so the strip chart and meter read absolute slope or merely deviation from a prescribed slope, the later being preferred.

In the audio alarm or warning circuit 29 two comparator amplifiers 78 are employed, both being connected to lead 77 through a separate potentiometer 80. These potentiometers set the trigger level of their associated amplifiers with respect to the error reflected on lead 77 with the amplifier outputs commonly connected to horn 81 through blocking diodes 82, arranged as shown. Thus when error level is exceeded in either direction the horn sounds.

Connected to the output of each comparator amplifier is a relay 83 which will be operated when the trigger level of its associated amplifier is reached. The armature of each relay is operable to close a contact 84 to connect battery voltage to an associated solenoid in the marker unit 58 to spray the appropriate paint color on the grade to physically indicate the error and type.

Leads to the solenoids also are connected to the strip recorder 62 (when used) to physically mark the strip when excessive slope deviation has occurred. Stopping and starting marks on the strip chart can be made with manual switches 86 which cannect the opposite polarity to the recorder over the aforementioned leads and also actuate the solenoids 85.

When using the strip chart recorder 62 an inverter 87 is connected to the battery to supply A.C. power to the strip chart recorder, the latter of which can be a commercial available unit, such as a Techni-Rites Model TR 711 built by Techni-Rite Electronics, Inc., Warwick, R.I. The tachometer generator 43 is used to control the chart speed and stylus deviation is controlled by the pendulum transducer output. Thus with the recorder an accurate chart of the slope can be made between starting and stopping points of the ground profile reader. Further multiple passes can be made and compared for greater accuracy of the slope profile of a given graded surface. Obviously some of the circuitry can be located remote from the frame, such as in a vehicle towing the reader. In place of the tachgenerator arrangement a flexible drive cable may be connected to one of the wheels and gearing in the recorder 62 to drive the chart therein.

Claims

What is claimed is:

1. A ground profile reader that provides a continuous slope reading normal to its transversed path along a monitored surface comprising:

an elongated beam oriented normal to such traversed path;

spaced apart ground engaging ski-type shoes attached to said longitudinal beam adjacent to its ends operable to support said longitudinal beam above such a monitored surface thereon, said ski-type shoes being adjustably attached to said beam so they can be adjusted longitudinally on said beam to avoid tracking directly in wheel tracks;

transport means connected to said longitudinal beam for moving it along a path normal to the orientation of said beam without interfering with its position established by said ground engaging ski-type shoes;

a level transducer unit adjustably attached to said beam operable to produce a continuous electrical output signal proportional to the deviation of its respective ground engaging ski-type shoes with respect to a vertical reference;

powered circuit means connected to said transducer unit; and

an indicator connected to said powered circuit mean operable to convert said continuous electrical output signal to a slope reading in degrees.

2. The reader defined in claim 2 wherein the transport system includes a triangular frame with a forward dirigible wheel for steering it.

3. The reader defined in claim 1 wherein the transport system has a recorder for recording a continuous slope variation read by the indicator.

4. The reader defined in claim 1 wherein the powered circuit means includes a warning means operable to sound an audible alarm when slope tolerances are exceeded.

5. The reader defined in claim 1 wherein the powered circuits include a marking means whereby areas of the monitored surface are physically marked when slope tolerances are exceeded by depositing colored material thereon.

6. The reader defined in claim 3 wherein the transport system includes distance measuring means operable to generation information concerning the distance traversed thereby with said distance measuring means connected to the recorder whereby correlated slope and distance information will be simultaneously read by said recorder.