IL38696A - Profilograph - Google Patents

Description

PATENT ATTORNEY 7 1 6 P R O F I L O G R A P H This invention relates to a profilograph, an instrument for measuring and recording undulations of the soil and providing a true graphic representation of relative heights in relation to the distance covered by - the .instrument· A number of height-distance recording devices, serving as auxiliary implements in road building, ground tilling, and levelling, are known to the art. The ones most commonly used work on the principle of a two-wheeled carriage the wheels of which revolve in one vertical plane (similar to a. bicycle) and which is provided with a pendulum or gyroscope* The distance covered, is measured by recording ' the revolutions of one or both. wheels, and the slope of the ground at each point of the way is determined by recording the (inclination of the pendulum or the deflection of the gyroscope. These recordings are then fed into a computer, which calculates the absolute or relative height of the ground at each point of the distance covered and, if necessary, presents a curve of the heights versus the distance travelled.

In another implement, the computer is mounted on the vehicle and may thus immediately produce the absolute or relative heights of points at regular intervals of the distance covered.

The main drawback of these instruments is that they are heavy and cumbersome to use and that they need considerable mechanical force means for propelling them of roost of the known implements is their inaccuracy, especially in measuring the relative heights of more widely spaced points.

Accordingly, the aim of the present invention is to provide a light implement for measuring the height-distance component of a field or road, which can be hand-propelled across the surface being measured and which instantaneously provides the profile of the covered distance im diagrammatic form* An additional aim is to produce very accurate measurements of the relative heights, if required.

The proposed implement consists mainly of a carriage possessing two wheels arranged one behind the other in a light frame so as to revolve in one vertical plane, of a damped pendulum oscillating in the same plane or a parallel one, and of an electro-mechanical recording mechanism for instantaneously producing a graph of the soil profile over which the implement is travelling. In order to explaia the operation of this instrument more fully, reference is made to the schematic representation shown in Figure 1 of the accompanying drawings.

Two wheels, 1 and 1 ' , are rotatably mounted on a triangular frame 2, their axles running parallel and their bisections lying in one and the same vertical plane.

A pendulum 3 is attached to the top of the frame in such a manner that it can oscillate in the same, or a parallel, vertical plane. The implement is pictured as being moved in R 4 the wheel 1, the actual distance being S a n*D, -re , where D is the outer diameter of the wheel* The geographic, horizontal distance covered, X, is shorter, the differential dS where 0/ dX at each point being dX = cos ©Yis the deflection of the pendulum from the normal to the line connecting the axles of the two wheels which, according to a well-known law of geometry, equals the inclination of the implement towards the horizontal* Accordingly, the total horizontal distance covered by travelling from a starting point Xq to the point X which the implement has reached is the integrated sum of the partial distances covered, viz* . ·.... · ■ ·. ■ ■.■. s ·■■ · ·.- X - X » I cos ©.dS " 0 ■ : \ The height increment at any point of the implement *s progress along the soil is dl * sin Q.dS, and the total height difference from an initial point to the height integrating over sentation for easy direct reading is a diagram of the profile plotted, on a suitably reduced scale, onto a paper tape of sufficient width* The implement of the invention is accordingly provided with means for feeding a paper tape to a recording device, both tape and. recording device being actuated by the pendulum and by the motion of the implement's wheel or wheels* The paper tape is moved across a fixed point at a speed exactly corresponding to the rate of horizontal progress of the dX ss a. cox ©. dS dt dt where a is the horizontal scale reduction factor and dS dt is the speed of the implement along the ground* The actual relative height o the implement at each point is marked on the tape by a stylus , which moves in the plane of the tape and at a right angle to its progress. At each point the sjferlus moves at a rate of dl « b.sin ft dS dt dt' where b is the scale on which the height is recorded. The stylus thus outlines, on a reduced scale, the exact profile of the ground over which the implement has travelled. The scale of the recorded height is usually bigger than that of the recorded distance travelled, for the sake of obtaining clear and correct readings.

The movement of the stylus is in a positive or a negative direction, depending on whether the implement's angle of inclination is positive or negative in relation to the horizontal, an ascending slope being designated a positive, a descending slope a negative, angle, as shown in Fig. 1.

The recording device according to the invention comprises the followingt- 1 ) an electrical tacho-generator generating a voltage as a linear function of its rotational speed, which is mechanically so connected to one of the carriage wheels that it rotates in a fixed relation to the speed of said ) an electric resolver of known design consisting of a stationary portion and a rotatable portion, the latter being mechanically connected to the pendulum in such a manner that it follows the changes in the pendulum*s angle of inclination deviating from its central position by an equal angle* The output of the tacho-generator as under (1) is fed into the resolver which then produces two different output voltages, one being proportional to the product of the said tacho-generator voltage and the sine of the pendulum inclination angle and the other proportional to the product of the tacho-generator a& voltage and the cosine of the pendulum inclination angle. ) two velocity-servo units of known design, each comprising a mojror and a tachogenerator mechanically coupled to each other, voltage amplifier means and feed-back means.

Each velocity servo unit is fed one of the two resolver outputs and is adapted to rotate at a rotational speed directly proportional to the respective resolver output. ) a tape of paper or other material movable in longitudinal direction and a marking or writing stylus movable in the plane of the tape in a straight line perpendicular to the sense of progress of the tape, said tape being mechanically driven by one of the velocity servo units at a speed proportional to the product of the tacho-generator voltage . and the cosine of the pendulum inclination, while the stylus is mechanically driven by the second velocity servo unit at a speed proportional to the product of the one or more constant voltage sources connected to the excitation windings of the aforementioned rotational units* In a preferred embodiment of the invention wherei the constant voltage sources are designed to supply alternating current toYexcitation windings, the resolver consists of a stator with one winding which latter is connected to the output of the tacho-generator obtaining its rotary movement from a carriage wheel, and of a rotor provided with two windings arranged perpendicular to each other, wherein each winding produces one of the two aforementioned voltages, in accordance with the angle formed between the respective rotor winding and the sta or winding* In the accompanying drawings, which illustrate a profilograph according to the invention, showing the essential elements only and omitting the auxiliary equipment, Figure 1 is a diagrammatic drawing of such a unit moving across an undulating terrain, Figure 2 is a side view of complete unit, Figure 3 is a section through the pendulum and the resolver on line Α-Δ of Figure 2, Figure 4 is a diagrammatic section through a velocity-servo-unit drum moving the paper tape, velocity-servo-unit, and the drive mechanism for advancing the recording stylus, Figure 6 is a modification of the mechanism for advancing the writing stylus, figure 7 is a typical w-i-r.iag,- diagram of the electrical part of the recording mechanism for alternating current, ' ■ ί and 9 Figures 8 * shows the manner in which the movement of a velocity-servo-unit is transmitted to the writing stylus by means of a potentiometer and a pen motor, and & -;-*>¾-Figure †0 is a typical wiring diagram of the electrical part of the recording mechanism for direct current.

In the profilograph shown in figures 2 and 3 two solid-rubber-tired wheels 1 and 1 ' rotate in bearings fixed in a steel frame 2. The latter is provided with an upper horizontal platform 5 for accommodating the different parts of the recording mechaniara. oA tacho-generato 9 of known design, mounted on the platform, is driven by the carriage wheel 1 through a chain drive comprising a large chain wheel 10 υο-axially fastened to the wheel 1, a smaller chain wheel 12 mounted on the generator shaft, and a chain 11 connecting the two chain wheels.

Approximately in the centre of the platform 5 a pendulum 3 is suspended from one end of a shaft 13, which freely rotates in a bearing 6 mounted in a bearing support 7.

The pendulum swings between two quarter-arc magnets 8 which damp its movement. Means are provided for changing the gap between the magnets 8, thereby to adjust the damping force. To the other end of the pendulum shaft 13, which projects beyond the bearing, the rotor 14' of an A.C. - resolver 14 is firmly fixed, and four collector rings 15 rotating with the shaft 13 are substantially evenly spaced between the The two rotor windings of the resolver 14 are each , wired to a pair of the four collector rings 15. The stator winding 17 of the resolver is so arranged that its axis is in line with one of the rotor windings 16 when the pendulum is in its central, vertical position, and at a right angle to the axis of the other rotor winding. The ends of the resolver's stator windings are connected to the ends of the output winding of the tacho-generator 9.

The platform 5 further accommodates two velocity-servo-units 18, which advance the paper tape and the writing stylus respectively and which are shown in greater detail in Figs. 4 and 5. The servo-motor 19 and the tacho-generator 20 are both of the drag-cup type and are mounted on a common shaft 21 , which rotates in bearings inside a common housing 22 and one end of which protrudes far beyond the housing. The far end of shaft 21 is provided with a worm 25, which meshes with a horizontal worm-wheel (not shown), forming a worm-gear 26· In the apparatus shown in Fig. 4 the vertical worm-wheel shaft 27 bears a vertical drum 28 rigidly fastened to it, forming the mechanism for advancing the paper tape. A second vertical rotatable drum, 28*, mounted on a bearing support 29 is positioned at a distance from drum 28, and a paper tape is wound round the two drums.

In Fig. 5, the shaft 27 is in the form of a fine screw, on which a non-rotating nut 31 moves up or down as dictated by the direction of rotation of the shaft 27. A styljtf 30 is The two mechanisms shown in Figs. 4 and 5 are mounted on the platform 5 (see Fig. 2) in such a way that the stylus is in contact with the paper tape and marks the position of the carriage at any given moment, resulting in a continuous curve of the ground profile* In cases where the profile contains considerable height differences, the width of the paper tape may not be sufficient to accommodate all the heights, and the arrangement shown in Fig. 6 will then be of advantage. Herein, the servo-motor 18, over a worm-gear 26, drives an endless chain 34 whish has, in the specific case shown here, four writing styli 30, 30*, 30", and 30"·, equidistantly fastened to its peripher. The distance between each two styli is somewhat less than the tape width, so that whenever one stylus crosses the upper or lower paper edge, the adjacent stylus commences marking the paper from its opposite edge* By counting the beginnings of the curves along the way covered the absolute height X can easily be calculated.

For the sake of simplicity the bearings in the drawings have been shown to be of the sleeve type, but in order to reduce friction losses to a minimum, ball or roller bearings on all rotating parts will be found to be of advantage.

The operation of the recording mechanism will now be explained with reference to the circuit diagram appearing in Fig. 7, wherein all components are shown as electrical symbols, reference numbers being identical with the corresponding parts shown in Fig. 2. Electrical connections are represented by The tacho-generator 9, revolving at a speed proportional to the carriage speed v, generates a output voltage which is directly prpportional to v. Excitation of the generator is provided by an external voltage source supplying a constant A.C* - voltage U to the excitation. winding 9', which is positioned at a right angle to the output winding 9". The latter forms a closed loop with the stator winding 17 of the resolver 14, the axis of said stator winding running parallel to the axis of one of the crossed windings 16 and 16' of the resolve rotor when the pendulum 7 (Fig* 2) and the rotor are in the central position, i.e. when the carriage is resting on level ground* In the situation depicted, however, the pendulum is deviating from its central position by an angle ©. Likewise, the axes of the rotor windings form angles 0 and (90 - ©)° respectively with the axis of the stator coil* The voltages and Uj induced in these windings are therefore proportional to the product of the imposed voltage Xf^ and respectively the # sine and the cosine of the angle 6.

The voltages and are amplified and imposed on the stator windings 23* and 24*, and 23" and 24", of two preferably but not necessarily identical servo-velocity-units 18' and 18", each comprising a motor 19*, 19" and a generator *, 20" mounted on the same shaft with it. The two high-gain amplifiers and A^increase the voltages in the motor windings to a degree sufficient to result, in conjunction with the action of the excitation windings, in the rotation of the motor and hence that of the generator on the same shaft. The excitatio n 24* and 24" of the two generators are connected in series across the voltages IJ^ and U^, respectively. The rotating generators induce voltages in the stator windings 24' and 24", which are so connected that the voltages generated in them are opposed and equal to the imposed voltages U2 and U^.

This results in a de inite number of revolutions for each voltage in direct proportion to the latter. The two servo-velocity-units are respectively coupled to the gear driving the drum 28 (bearing the paper tape) and the worm gear 25 (moving the stylus).

In orde to prove that each point of the ground covered by the profilograph appears on the tape in a one-to-one correspondence, the following formulae are giveni- where is a conversion factor taking into account the transmission from the carriage wheel to the generator as well as electrical factors.

U2 « K.| .K2.v.sin © where is another conversion factor charadteristic of the servo-motor unit.

Integrating for the distance X and the height X after having traversed the way S yields X » I K^.K^.v.cos ©.dt Substituting in these latter two formulae v » dS/dt produces Ϊ K^ ^sin O.dS and X = K..K_.cos O.dS. similarly Both X and Ϊ are seen to be independent of the time, i.e. the speed of the carriage is without influence.

So that two identical servo-motor units can be used, the gears driving the drum 28 and the stylus 30 should be designed with appropriate ratios, height and distance thus being reduced to the different scales used.

The wiring diagram for direct current shown in Figure i'JD is in principle identical with that illustrated in Figure 7 and described in the aforegoing, with the exception of the resolver which is a sine/cosine potentiometer of known design.

It will be seen that the remaining equipment is designed for direct current and this requires different wiring in some places, however this is easily understood and carried out by a person versed in the, art, and need not be explained in detail.

The two amplifiers are marked SA2 and SA3 since they are known as "summing amplifiers" used with direct current. It should also be noted that one collector of each tacho-generator 20Λ as well as each amplifier are either grounded or interconnected.

The formulae elaborated in connection with the D,C. diagram apply equally in this case, and for this reason the same designations have been utilized for equivalent equipment in both Figures* The mechanical transmission of movement to the writing stylus as shown in Figs. 5 and 6 may be replaced by an electrical transmission, as shown in Fig. 8f9« Herein, the sliding contactor 41 of a circular potentiometer 40, rigidly attached to the shaft 21 of a servo-motor unit 18, moves over the total length of a circular resistor 42 while the shaft makes a complete revolution. One end - marked "A" - of the circular resistor 42 is connected to the positive terminal of a voltage source, while the other end - marked "B" - is either connected to the negative terminal of the said voltage source or earthed. From the contactor 41 a wire 43 leads to a recording galvanometer or pen-motor 44, which moves a stylus 30 across the paper tape 39.

The advantage of this device is that it dispenses with the necessity for a plurality of styli for representing greater height differences, where the paper is not wide enough to accommodate a complete curve and when it is not desirable to reduce the height scale. The contactor 41 travelling over the resistor 42 from "A" to nB" furnishes to the coil 45 of the galvanometer a voltage which decreases from a maximum value at point "A" to a minimum value at point "B", so adjusted as to result in a movement of the stylus across the entire width of the paper tape. When, as a result to its maximum value, and the stylus, accordingly, returns to the opposite edge of the paper. In this manner a number of curve beginnings ca be made on the paper by one stylus only, depending on the scale of reproduction and the elevation differences of the soil.

The wheels of the carriage are made sufficiently wide, so as easily to balance the equipment while, travelling over rough ground} but in order to give the carriage still greater stability a third and possibly a fourth wheel may be fitted to the carriage in a suitable manner. The wheels are not necessarily of the same diameter as illustrated in the drawings but may be of different size if this is structurally advantageous.

When a relatively short distance is to be measured, it may not be necessary to use a second #rum, 28 f, for tensioning the paper tape, and the tape may be wound once round the mai drum 28» The transmission means for driving the tape and/or the stylus may be modified in different ways:- For instance, the worm gears shown and described in the foregoing may be replaced by other gear transmissions, as for instance epicyclic gears.

On the other hand, the speed and power of the velocity-servo-units may be chosen in such a way that the use of gear transmissions can be dispensed with. In this case a drum or roll for movement of the tape may be fixed direct to the - down across the tape. This arrangement requires the placing of one of the velocity-servo-units with its axis vertical and the other unit with its axis horizontal , in order to obtain crosswise movement, of the tape and the stylus* Other modi ications o alterations majt be made to the equipment within the spirit of the invention and the scope of the appended claims*.

Claims (1)

1. · A pro ilograph in the form of a carriage possessing two wheels aligned to revolve in a common vertical plane, a pendulum oscillatin in the same or a parallel vertical Ί plane, and an electro-mechanical recording mechanism for producing a profile of the covered distance in diagrammatic form, this recording mechanism comprising 1 ) an electrical tacho-generator; generating a voltage as a linear function of its rotational speed which is mechanically so connected to one of the carriage wheels that it rotates in a fixed relation to the speed of said wheel, thus its output being proportional to the rate of progress of the carriage, 2) an electric resolver of known design consisting of a .stationary portion and a rotatable portion, the latter being mechanically connected to the pendulum in such a manner that it follows the changes of the pendulum's angle of inclination deviating from its central position by an equal angle, said resolver receiving as its r'- input the output from the tacho-generator as under (1) and producing two different voltages, one proportional to the product of the tacho-generator voltage and the sine of the pendulum inclination angle and the other proportional to the product of the tacho-generator voltage and the cosine of the pendulum inclination angle, 3) two velocity-servo units of known design, each comprising a motor and a tacho-generator mechanically coupled to each other, voltage amplifier means and feed-back means each unit b in f d rotate at a rotational speed directly proportional to said imposed voltage, 4) a tape of paper or other material movable in longitudinal direction and a marking or writing stylus movable in the plane of the tape in a straight line perpendicular to the sense of progress of the tape, pendulum inclination, while the stylus is similarly driven by the second velocity servo unit at a speed proportional to the product of the taoho-generator voltage and the sine of the pendulum inclination, 5) one or more constant voltage sources connected to the excitation windings of the aforementioned rotational units. · Λ profilograph as claimed in Claim 1 wherein the constant voltage sources are designed to supply alternating current to the excitation windings, and wherein the electrical components are designed for alternating current in a known manner. · A profilograph as claimed in Claim 2 wherein the resolver of known design consists of a stator with one winding which is electrically connected to the outpu;t of the tacho- generator driven from a carriage wheel, and of a rotor coupled to the pendulum and provided with two windings arranged perpendicular to each other, wherein each winding produces one of the two resolver voltages as under (2) in Claim , in accordance with the angle formed between the 4* A prdfilograph as claimed in Claim 1 wherein the constant voltage sources are designed to supply direct current to the excitation windings, and wherein the electrical components are designed for direct current in a known manner* 5* A pro lograph as claimed in Claim 4 wherein the resolver is in the form of a potentiometer of known design and possesses a rotatable contactor arm rigidly connected to the pendulum shaf which arm is adapted to slide along circularly arranged resistors of suitable dimensions* 6* A profilograph as claimed in Claim 1 wherein the pendulum is provided with magnetic or electro-magnetic damping means* 7* A profilograph as claimed in amy of the preceding Claims wherein the rotational movement of the specific velocity- servo unit is converted into a progressive movement of the paper tape by means of a worm gear having a drum rigidly fixed to the shaft of the worm wheel* 8. A profilograph as claimed in ajjiy of the preceding Claims wherein the rotary movement of the specific velocity-servo unit is converted into a progressive movement of the stylus by means of a wormgoar having the shaft of the wormwheel shaped to form a lead-screw on which a screwed nut, with the stylus attached and guided in a slot, can be moved in longitudinal direction upon rotation of said screw. 9. A profilograph as claimed in any of Claims 1 to 7 wherein the rotary movement of the specific velocity-servo unit is and a reoording galvanometer calibrated to give a deflection proportional to the elevation expressed, by the revolutions of the said velocity-servo unit* A profilograph substantially as hereinbefore described and illustrated in the accompanying drawings. For the applicant Technion Research and Development Foundation Ltd*