US3896885A

US3896885A - System for automatically aligning and/or moving in a parallel movement path a guide seating structure adapted for guiding the movement of a tool mounted thereon

Info

Publication number: US3896885A
Application number: US504702A
Authority: US
Inventors: Carl Lennart Dahlstrom; Tord Richard William Ponton
Original assignee: Skanska Cementgjuteriet AB
Current assignee: Skanska AB
Priority date: 1970-12-11
Filing date: 1974-09-10
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29

Abstract

The object of the invention is a system for automatically setting the angles of the guide seating structure of a rock drilling machine or the rammer of a pile driver, or a similar tool arranged for a reciprocating movement on said structure carried by a movable support and for moving the structure parallel to itself so that the angle of the structure is maintained. The structure is pivotally mounted in two substantially vertical orthogonal planes and is connected to the movable support by a movable intermediate arm provided with drive means such as jacks for pivoting movements of the structure in said two planes. Transducers are mechanically coupled to the drive means to transmit electrical signals representing angles to a comparator in response to the attitude of the guide seating structure, the intermediate arm and the seating structure to adjust the seating structure to a specific bearing and a specific angle, in said two planes, in relation to the vertical, the bearing and the specific angle being automatically maintained when said movable support carrying the guide seating structure is moved to another place even on a terrain of varying slope so that a further hole may be drilled or a further pile may be driven exactly parallel to a preceding one.

Description

United States Patent Dahlstrom et a1.

1451 July 29,1975

[54] SYSTEM FOR AUTOMATICALLY 3,6l2,190 10/1971 Wills 173/20 A 3,625,483 l2/l971 SIOIICI' 280/6 H PARALLEL MOVEMENT PATH A GUIDE SEATING STRUCTURE ADAPTED FOR Prmzary bxammerErnest Purser GUIDING THE MOVEMENT OF A TOOL Attorney, Agent, or FzrmP1erce, Scheffler & Parker MOUNTED THEREON [Q7 ABSTRACT [75] Inventors: Carl Lennart Dahlstrom, Savedalen; 1 Tord Richard William Pomon, The ob ect of the 1nvent1on 1s a system for automat1- MoIndaI both of Sweden cally setting the angles of the guide seating structure I of a rock dr1lI1ng machme or the rammer of a p1le Asslgneei AB Skanska Cememglutel'let driver, or a similar tool arranged for a reciprocating Sweden movement on said structure carried by a movable sup- I22I Filed: sept 10, 1974 port and for moving the structure parallel to itself so that the angle of the structure is mamtamed. The

[ PP 504,702 structure is pivotally mounted in two substantially ver- Related Application Data tiIclal orthogorIgal planes and is conrzIected to the nadovII [63] Continuation of Ser. No. 206,480, Dec. 9, 1971, e F y amova 6 f prov e abandoned with dl'lVC means such as acks for p1vot1ng movements of the structure in sa1d two planes. Transducers I30] Foreign Appncafion Priority Data are mechanlcal ly coupled to the dr1ve means to trans- I68I H mlt electrlcal slgnals representmg angles to a compar Dec. 11,1970 Sweden SI 7 ate], in response to the attitude of the guide Seating Apr. 21, 1971 Sweden 51 1 structure the Intermediate arm and the seating Strum ture to adjust the seating structure to a specific bear- [52] U.S. C1. 173/2, 33/;ZgI217238/3/2g Ing and a Specific angIe, In Said two pIaneS In reIatIon SI I CI E21 11/02 to the vertical, the bearing and the specific angle f 248/2 being automatically maintained when said movable 1 0 care support carrying the guide seating structure is moved to another place even on a terrain of varying slope so [56] References Clted that a further hole may be drilled or a further pile may UNITED STATES PATENTS be driven exactly parallel to a preceding one. 2,101,837 12/1937 Blanchett 280/6 H 3,481,409 12/1969 Westerlund 173/43 21 D'awmg F'gures Wn/TrTuGficuTfiuRm G I l5 I LFROM oonmmmnfls E fiB 11 5111 +5 PULSE nvnlmu I 213312 muvmc 501.511. PISCIOII I STAGE VALVE FEED l .R\\ BEAMIL I x.1' FHY I I l PENEL REENEEE l I I g 11%; I0 I L. l l I" film n 5LPE l 1 l I nf l c li t on I 20R fsgafa SELEUOR 011 FROM l COURSE f I l I I COMPARATOR l i' u n LHLT J I INDICATOR I III I I I I I I/l R0"- 1 o D O 1.0w AMPL. PULSE 4 vuruul it??? lac-mat I P731 211 IIE E' ts??- 3116'? 1215; 3, 9 l I W.SI GHT UFLING -(-l) I I SLO-PE LAT R 11L} I zlfil'l'lAcTloN I SELECT, ,7 I K cos(%*t I l K241 LOW l I ma 1 I OPERATING CIRCUIT TILTING SHEET PATENTED JUL2 9 I975 SHEET PATENTED JUL 2 9 I975 6 0: .z i ww 10 fl 1 5 1 w we W1. "Ev m a 14 oz; 9: v. Q G m u m NOE SHEET PATENTEI] JUL 2 9 I975 SHEET PATENTEU JUL29|975 PATENTEUJULZSIHIS 3,896,885

sum e FIG.7

mcuumou OF FEED BEAM BEARING PATENTEBJULZQIHYS 3,896,885

SHEET 7 FIG.8

INCLINATION OF FEED BEAM )5 SYSTEM FOR AUTOMATICALLY ALIGNING AND/OR MOVING IN A PARALLEL MOVEMENT PATH A GUIDE SEATING STRUCTURE ADAPTED FOR GUIDING THE MOVEMENT OF A TOOL MOUNTED TI-IEREON This is a continuation of application Ser. No. 206,480 filed Dec. 9, 1971 and now abandoned.

The present invention relates to a system for automatically aligning and/or moving in a parallel movement path a guide seating structure adapted for guiding the movement of a tool mounted thereon, the guide seating structure being pivotally mounted in two planes located at angles relative to each other on elements which are arranged to support the seating structure and connected between the structure and a movable support unit and provided with drive means for effecting the pivoting movements of the guide seating structure in the aforementioned planes.

Guide seating structures of the type envisaged are used, inter alia, in the form of feed beams or runners for rock drilling machines which are arranged for reciprocating movement along the beams, although such seating structures may also be used in other connections, for example in the form of guide structures along which working tools such as drop weights are arranged to move.

When using such guide seating structures it is important that they can be aligned to point in the desired direction as simply and as accurately as possible and that they can be moved in a parallel path of movement from one working site to another, so that the tools arranged thereon retain the same position in relation to the vertical and to the horizontal. This is the case, for example, with guide seating structures having the form of runner beams for rock drilling machines, in which cases it is often desired to change both the angle at which the beams are inclined to the horizontal and the direction in which the seating structures are pointed, i.e. their directional bearing, a task which has hitherto been relatively time consuming and which requires a high degree of precision in order to obtain sufficient accuracy, and wherein with tunnelling and bench blasting it is of great importance that adjacently situated drill holes extend parallel to one another. For these purposes, the guide seating structures of rock drilling machines are arranged for pivotal movement in the aforementioned two planes, the guide seating structures being guided manually and moved by means of their respective drive means in a manner such as to enable them to be brought into desired positions and when moved from one working site to another the seating structures can be adjusted so that parallellism is obtained between the settings of the seating structures at the different working sites. This, however, is a method which must be carried out with great accuracy and which is consequently highly time consuming particularly if a sufficiently accurate degree of parallellism is to be obtained when bench blasting, with which it is often difficult in practise to check the bearing of the guide seating structures.

Although certain suggestions have been made for varying degrees of mechanized alignment and parallel movement of the feed beams of rock drilling machines, none of these proposals have paid sufficient attention to the influence of the widely varying contours of the surface to be drilled in bench blasting operations, or to.

the bearing of the beams, the word bearing being used here to indicate the direction in which the beams point in the horizontal plane.

The object of the present-invention is to eliminate the disadvantages associated with the aforementioned proposals and to provide a system of the type described in the introduction which in addition to the fact that it can be mounted directly to the elements forming the connecting means between the support unit and the seating structures, irrespective of the design of the elements, also provides the desired setting of the seating structure both subsequent to a change in slope and to a change in direction of the supporting unit, without it being necessary for the operator to make a new setting on the system. In other words, the system according to the invention shall be capable of providing a setting and parallel movement of the guide seating structures or the feed beams which is substantially independent of the machineconstruction, the contours of the ground and the bearing.

Practical tests carried out on embodiments of a system according to the invention show that the aforementioned objects are satisfactorily achieved and that by means of said system it is possible to align and adjust automatically the guide seating structure with respect to its bearing and inclination to the vertical and to move the guide seating structures automatically in a parallel pattern of movement. The system of the present invention thus affords a solution to a problem which was difficultly resolved and time consuming and enables the desired inclination and bearing of the seating structures to be obtained easily and precisely, simply by making certain settings on an instrument panel.

The system of the present invention is mainly characterized in that interconnected transducers and comparison units are coupled to the drive means of the guide seating structure and are arranged to transmit signals in response to the attitude of the supporting unit, the means connected between the guide seating structure and the supporting unit and/or the seating structure to adjust the seating structure to a specific bearing and a specific angle in relation to the vertical.

The invention will now be described with reference to the accompanying drawings, further features of the invention being disclosed in connection therewith.

In the drawings, FIG. 1 illustrates diagrammatically a side view of a mobile rock drilling unit provided with guide seating structures in the form of feed beams arranged to guide thereon tools in the form of rock drilling machines arranged for reciprocal movement along the beams,

FIGS. 2 and 3 are simplified, diagrammatic views of the rock drilling unit seen in top plan view and from the rear,

FIG. 4 is a block diagram of an embodiment of the system according to the invention responsible for adjusting the positions of the feed beams and moving the same in a parallel pattern of movement,

FIG. 5 is a view corresponding to the view of FIG. 2 and illustrates a rock drilling unit provided with a system according to the invention intended for adjusting the positions of the feed beams and moving them in a parallel pattern of movement,

FIG. 6 is a block diagram of the embodiment illustrated in FIG. 5, and

FIGS. 7 and 8 each show an example of calculating means for controlling the feed beams of a drilling unit according to FIG. 5.

The rock drilling machine illustrated in FIGS. l-3 and FIG. is of purely conventional construction. The machine is supported on a body member or support unit 2 mounted on tracks I, which enable the unit to be moved on the working site. In the illustrated embodiment, the body member 2 pivotally supports two folding jibs 3 which can be raised and lowered relative to the body member. The folding jibs are attached at one end to the body member and each of the jibs carries at its free end a feed beam 4. The feed beams comprise guide seating structures for guiding a rock drill unit 5 arranged thereon, each of the drill units being arranged for reciprocating movement along its associated beam thereby to move a-drill 6 to the desired working position.

The two feed beams or seating structures 4 are mounted on the jibs 3 in a manner which enables them to be pivoted in two planes at right angles to each other so that the seating structures can be tilted and turned relative to a vertical line through their pivoting axes. The tilting and turning movements effected by the seating structures in planes perpendicular to each other are illustrated in FIGS. 1 and 3, in which the tilting angles and the turning angles are shown by the reference 'y and y respectively, these angles thus lying in their respective one of the two planes. The pivoting movements of the seating structures 4 in the aforementioned planes are effected by means of drive units in the form of

hydraulic mechanisms

7 and 8. The hydraulic mechanism 7 is responsible for movement of the seating structure in the tilting plane, while the hydraulic mechanism 8 is responisble for movement of the seating structure in the turning plane. The

hydraulic mechanisms

7,8 cooperate with hydraulic mechanisms (not shown) for manoevring the folding jibs 3 by means of oil pressure obtained from one or more pumps mounted on the body member 2.

In as much as a system according to the invention is intended both for adjusting the position of a seating structure for guiding a tool arranged thereon and for moving the seating structure in parallel movement patterns and since the illustrated embodiment is provided with two' such seating structures, namely the feed beams 4 supporting the rock drilling units 5, which beams can both be adjusted and moved in parallel movement paths individually between their different operation positions, two co-acting devices must be arranged in the two illustrated embodiments. In accordance with the invention, the co-acting devices comprise interconnected transducer and comparison units coupled to the drive means 7,8 of each seating structure or feed beam 4, the transducer and comparison units being arranged to transmit signals for automatically adjusting each of the seating structures to a specific bearing and to a specific angle relative to the vertical in response to the attitude of the body member 2, the means in the form of folding jibs 3 coupled between the body member and the seating structures and/or the individual attitudes of the seating structures or feed beams.

In view of the fact that a system according to the invention in addition to determining the attitude of the tion so as to facilitate understanding of the invention. With respect to the first embodiment, FIG. 2 also illustrates how a signting device co-acting with a direction or course indicator 9 mounted on the body member 2 is adjusted to the desired course or bearing for the feed beams 4. In respect of the second embodiment, FIG. 5 illustrates in a corresponding manner how the sighting device co-acting with course indicators mounted on the body member 2 and corresponding to at least one of the course indicators 12 mounted on the feed means is adjusted to the desired course or bearing for the feed beams 4.

For the sake of simplification, the block diagram illustrateed in FIG. 4 for the rock drilling unit illustrated in FIGS. I3 and relating to the first embodiment of the system according to the invention, in addition to the circuits for the bearing of the body member 2, only shows the operating circuits for effecting movements in the turning and tilting planes for one of the two feed beams 4 associated with the unit in question.

As will be evident from FIG. 4, in principle the operation of the system is similar to that of a fire control system for naval artillery. The course indicator 9, which is the all important unit for determining the bearing of the feed beams, may be constructed in different ways and, for example, may comprise a compass provided with a compass indicator housing rotatably mounted in an operating box and provided with a course follower capable of being actuated from without by means of gears via a transmission having a gear ratio of l:(l The course follower is connected through the transmission with the knob of a resolver 10 in a manner such that rotation of the resolver knob in a clockwise direction results in anitclockwise rotation of the course follower and vice versa. As will be seen from the reference disclosed in FIG. 2, the references for both the resolver knob and the course follower in the longitudinal direction of the drill unit is straight forwards. To facilitate work connected with adjusting the bearing of the feed beams which, inter alia, may be given in relation to sighting marks on the ground, the indicator housing of the course indicator 9 is suitably provided with an attachment means for a sighting telescope or the like. The sighting telescope should be connected to the indicator housing by means of the attachment means such as to be stationary with respect to the housing but arranged for rotation with the housing in the operating box and have a reference position pointing straight forwards in the longitudinal direction of the drilling unit, i.e. that a special designation, e.g. N, on the scale of the indicator housing points straight forwards in the longitudinal direction of the unit.

With respect to the angles a, B and III, illustrated in FIG. 2, a transmitter portion of the course indicator 9 transmits signal voltages to the resolver 10 which constitute a measurement of the angle (B-l-tb). When the course indicator needle lies on the designation N on the scale of the indicator housing the angle (Bi'lil) is 0, while the bearing of the drilling unit is also 0.

To obtain behind the resolver 10 a signal which is representative of a measurement on only the angle 4:, which indicates the desired angular deviation in the feed beam bearing relative to the longitudinal direction of the unit pointing straight forwards, it is necessary with the system of the embodiment illustrated in FIG. 4 to direct the sighting telescope, and as a result thereof also the indicator housing for the course indicator 9, to

the desired bearing and locked therein'. -Ther'eafter,- the knob on the resolver is'turne'd so that the course follower of the courseindicator is movedin a direction coinciding with the direction of the indicator needle,

whereupon the resolver knob is locked. Subsequent to these measures-being taken, the settingnofthe system provides reference .values for-all future'changes in direction of the drilling unit provided that the adjusted desired bearing is to be maintained, i.e. the signal behind the resolver 10 is always a measurement on the angle t1: irrespective of how the drilling unit is turned on its tracks 1. r

Setting of the feed beam bearing by means of a system according to FIG. 4 can be explained simplest by assuming that the sight with the indicator of the course indicator 9 and the course follower and therewith also the knob of the resolver 10 all point straight forwards in the longitudinal direction of the drilling unit. The needle of the course indicator will then take a position corresponding to the angle (B+il1) in relation to the longitudinal direction of the unit and therewith also in relation to the course follower. If the sight is now turned together with the course indicator to the angle (-111) so that the sight points in the desired direction for the feed beams 4, the course indicator needle will still show the angle 5w) relative to the scale on the course indicator, but will itself take the angle B relative to the course follower and the straight forward direction in the longitudinal direction of the unitQIf the knob of the resolver 10 is now set so that the direction in which the course follower extends coincides with the direction of the indicator needle, i.e. with the angle (-8), while the course follower turns anti-clockwise when the resolver knob is turned clockwise, the resolver subtracts the angle ,8 from the course indicator reading, whereby the output signal from the resolver 10 is a measurement of the angle (11 unit a new setting is made, irrespective of how the drilling unit is turned.

If the sight is not required for use in adjusting the feed beams to the desired bearing, but that the number of degrees through which the feed beams must be moved in order to reach the bearing are known, the requisite number of degrees can instead be set directly on the knob of the resolver 10, since the course follower connected thereto is also rotated to the desired position on the course indicator scale. Thus, in this instance use of the sight is obviated, the sight being mainly intended to obtain bearing settings for which only reference objects in the surrounding territory are found.

With the system shown in the block diagram of FIG. 4, attached to the pivot by which a folding jib 3 is connected to the body member 2 of the drilling unit is the resolver 11 which senses the swinging movements of the jib in the plane of the ground and relative to the body member. The resolver 11 is not illustrated in FIGS. l3, but is shown graphically in FIG. 4.

Moreover, a, is added'in theresolver 11 to the signal arriving from the resolver l0and the sine and cosine of the sum is formed, whereby the relations K sine (a,, +xl1) and .K cosine (04,, +41) are obtained as output signals to;the two operating-

circuit

15 and 16 for a feed beam 4,.the signals comprising references for rotation and tilting, respectively, ofrthe feed beam setting.

Incorporated in the operating

circuits

15 and 16 is an inclination selector 17, whichmay be-either of the socalled continuous type orso-called indexing type and is intended for adjusting the slope of the feed beam relative to the vertical. The signals arriving from the resolver 11 and combined subsequent to being demodulated and filtered in the two operating

circuits

15 and 16 with the signal arriving from the inclination selector 17, which is common for the two circuits, and is then transmitted in the form of a set-point signal for the slope of the feed beam in its plane of rotation and a setpoint signal for the slope of the beam in its tilting plane to each of the comparison means 18 and I9 incorporated in the two operating circuits. A control signal is then transmitted from the comparison means 18 in the operating circuit 15 for movement of the feed beam 4 in the rotation plane, which actuates a solenoid valve of the hydraulic mechanism 8, the hydraulic mechanism moving the feed beam in its plane of rotation until the desired position is obtained. Arrival at the desired position is decided by a signal transmitted from an appropriate pendulum transducer 20 mounted on the beam in its plane of rotation and arranged to detect the angular position thereof, which signal, subsequent to being suitably processed, is returned to the comparison unit 18.

As will be evident from the aforegoing, the transducer means provided in the system according to the invention comprises, inter alia, means which sense angles in the plane of the ground.

In the described embodiment, the transducer means comprise the means co-acting with the course indicator 9 mounted on the body member 2 and thus primarily the resolver l0 and the resolver 11 which is mounted on the attachment pivots of the folding jibs 3 to the body member 2 and senses the-mutual angle between respective folding jibs and the body member. Furthermore, the transducer means comprises means which sense angles in the vertical plane, which means in the described embodiment comprise two vertical sensing instruments or

pendulum transducers

20 and 21, which are mounted on the feed beam or on the seating structure 4, or which in principle may be mounted on the rock drilling machine 5 in their respective ones of the two vertical planes in which the seating structure or beam 4 is capable of moving.

The acutal setting of the angle of the feed beam or seating structure 4 in relation to the vertical and the bearing of the feed beam or the seating structure is effected, as previously disclosed, by means of the inclination selector 17 with respect to the angle and a selector means, for example in the form of a resolver 10, with respect to the bearing, coacting with the instrument disclosing the direction, in the present case the course indicator 9.

The embodiment of the system according to the invention illustrated in FIG. 4 can be applied in such instances when the body member 2 is in a substantially horizontal position and will adjust the position of the feed beams 4 with sufficient accuracy to satisfy the majority of requirements in practice when the slope of the ground varies to a moderate extent. The most important advantage with this embodiment is that one single course indicator is able to serve several seating structures or feed beams 4 and that in certain case it has been found more suitable to position the course indicator on the body member. On the other hand, the embodiment disclosed in the block diagram of FIGS. 6 and 5 can be used when no requirements are placed on a substantial horizontal attitude of the body member, i.e. irrespective of variations in ground slope.

With the embodiment of FIGS. and 6, a course indicator 12 is used for each separate feed beam 4 so that information concerning the two vertical planes in which respective feed beams are turned and tipped can be obtained directly from the course indicators (see FIG. 5). This is achieved, for example, by the fact that the course indicator 12 (FIGS. 5 and 6) is mounted either on the actual feed beam 4 or on an extension thereof, where it is oriented so that it discloses directly the direction of the vertical plane in which the beam or the seating structure 4 is tilted. The course indicator 12 may also be mounted on the actual tool, i.e. in the illustrated embodiment on the drilling machine 5, since the tool is unable to rotate around an axis in the longitudinal direction of the seating structure or the feed beam 4.

When initially aligning the feed beams on marks in the surrounding countryside while using the second embodiment of the system according to the invention, the body member 2 shall be positioned horizontally and at least one folding jib 3 should be directed straight forwards in the longitudinal direction of the rock drilling unit, see FIg. 5. The procedure when adjusting the position of the different members is then similar to that undertaken with the first embodiment of the system according to the invention. It should be mentioned, however, that the resolver knob is common to the two feed beams 4 and is therefore connected to the resolver l0 cooperating with each of the beams. In this way, the angle ,8 can be subtracted simultaneously for the two feed beams, which means that the outgoing signal from each of the two resolvers 10 is a direct measurement of l om and lll respectively. As will be seen from FIG. 5, (1J0 discloses the angular deviation between the vertical planes in which the beams are tipped and the desired course direction or bearing. I

When the direction in which the feed beams are directed is adjusted according to information obtained from the course indicator, the procedure is the same as that taken with the previously described embodiment of the system according to the invention, i.e. the requirement of a horizontal position and forward direction of a folding jib is obviated.

The block diagram illustrated in FIG. 6 also discloses only one of the feed beams 4 embodied in the apparatus. The system illustrated in FIG. 6 also operates in a manner approximately similar to a fire control system for naval artillery.

The course indicators 12 of the illustrated embodiments are combined transducer devices arranged to transmit signal indicative of the direction in which the feed beams are pointed and their indication and are immovably connected with their respective feed beam 4 or other type of seating structure or the working tool and will always move together with the tool. Thus, with the exemplary embodiment it is not necessary to provide universal joints or other forms of pendulating suspension means or corresponding stabilized platforms. The coordinate system of the aforementioned transducers is thus established in relation to the seating structure and movable relative to the vertical and to the gravitational and magnetic field of the earth, and consequently it is necessary to make corresponding calculations for obtaining signals for adjusting the seating structure to a determined bearing and to a determined angle relative to the vertical.

The following advantages are gained by mounting the transducers stationarily with respect to the seating structures 4:

a. attachment of the indicators to the seating structures and the attachment members necessary therefor can be effected with comparative case;

b. the transducers need not be constructed to contain movable components or to cooperate with such movable components as inclination indicating pendulum transducers or the like,

0. Since the transducers are not fitted with movable components and since no mechanical damping means for pendulating systems and universal joint suspensions etc, are required, the transducers will operate more rapidly.

d. The risk of damage to the transducers and components cooperating therewith is less which is of great importance in the case of rock drilling units and similar machines operating under difficult working conditions.

Although a system employing course indicators having a magnetic compass and universal joint suspension together with pendulum transducers necessary therewith and optionally damping means and the like is at present less expensive than a system employing transducer means which by means of immovable elements determine the components of the earths magnetic field, even when taking into account the costs involved for the necessary automatic calculating means, the aforementioned advantages afforded by the latter system more than offset the extra costs involved. It should also be mentioned that a transducer which has no movable components and which is mounted directly onto the seating structures 4 is subjected to much harder vibration than a transducer mounted on the body member and possibly resiliently suspended by universal joint means, but modern devices for measuring the components of the earths magnetic field (in in the present instance it is only the angles of these components or their relative magnitude in relation to each other which need be determined) are very small and insensitive and can be readily mounted in position, optionally on shock absorbers or the like, and are of very inexpensive construction. Examples of such modern field component measuring devices are semi-conducting devices providing with so-called magnistors, magnetodiodes or fluxgate magnetometers. Hall-transducers and so-called field plates are less suitable for use at the present time.

FIGS. 7 and 8 each show an embodiment of a calculating means which transmits signals for controlling the desired tilting and rotation of the feed beams or seating structures 4, the tilting and rotation of the seating structure being effected by means of the

hydraulic units

7 and 8.

To enable the purpose and mode of operation of the devices illustrated in FIGS. 7 and 8 to be understood, a description will be given of the calculations which must be carried out by the devices. For the sake of simplicity, the description will be given solely with reference to the case when the rock drilling unit is provided with only one feed beam 4 having attached thereto a combined inclination and course indicator 12. In the case of two or more feed beams which can be rotated and tilted independently of each other, one indicating means and one calculating device must be provided for each beam.

The coordinate system of the combined indicator 12 is a right-angle right-hand system and is independent of the vertical or the coordinate system of the magnetic and gravitational field, the coordinate axes of the indicator being x, y and z. The vertical and the coordinate axis 2 of the indicator will only coincide when the feed beam 4 is vertically, i.e. when the axis 2 extends vertically downwardly, while x coincides with the straight forward direction of the interconnected member 3 and y is directed horizontally to the right in the transverse direction perpendicular to both the vertical and to the axis x.

The horizontal projection of the coordinate axis x forms the angle ill, with the desired bearing ,3. The coordinate axis 2 forms the angle 7 with the vertical. The desired inclination of the feed beam is 'y The prevailing tilt and rotation angles of the seating structure 4 (the control point values) are 7, and 7 The horizontal and vertical components of the earths magnetic field are 8,, and B respectively. The earth field components measured by the transducer in the transducer coordinate system 2:, y, z is B,, B and 8,, respectively. If the inclination angle of the earths magnetic field is designated j, the inclination I tg j B /B The signal representing the difference between the control-point value and the set-point value of the tilt is designated S, and the corresponding signal for rotation is designated S,,, these two signals being so-called error signals which control the tipping and rotating

hydraulic unit

7 and 8 by means of servo control means.

The following relationships are applicable for controlling the seating structure by means of the last mentioned signals:

S,. siny sim/ coslll (2) It is now assumed that there is used a transducer of known design which generates electric signals, each of which represent one of the three magnetic components B 8,, and B, suitably so that the signals are proportional to these components. Electrical signals are produced by the aforementioned signals in, for example, matching amplifiers (not shown) representing B /B B,,/B, and B /B representively. The ratio I= B,,/B,,, i.e. the value I of the inclination, which is equal to the tangent of the inclination angle, can also be formed in a similar manner. It should be observed that the vertical and

horizontal components

8,, and 8,, of the earths magnetic field can normally be considered constant, and hence it is only necessary to set these values once, although possibilities of adjusting the same should be found; setting of the values being effected by adjusting the amplification factor of the aforementioned matching amplifiers in a corresponding way. Thus, the two earths magnetic components need not be constantly measured by a special transducer or the like.

The calculating means illustrated in FIGS. 7 and 8 make calculations on the basis of the following:

B, 8,, cos (3 Sin 7+ B cos y cos y= cos 'yv cos yr (6) The variable y in the equations (3)-(5) is then eliminated by means of the equation (6), whereafter the three values w, W and th are calculated from these three equations.

The following relationships are obtained when inserting the inclination I tgj B /B B ,./B, cos (,8+lll cosyt 1 sin 7! (3a) In a manner similar to that when inserting the two, normally constant values B and 8,, in amplifiers which directly or by means of subsequent stages generate signals corresponding to B /B B lb, and B /B the ratio I B /B, can determine the amplification factor in amplifiers referred to more below. It should be mentioned here that the values I, B, and are natural values and, as is well known, may vary slowly with time and may be slightly different in different geographical areas. Information on such values is published annually by relevant authorities. In the following description it is assumed that the exemplary devices are provided with adjusting means to permit corrections to be made to the aforementioned values.

In connection with the following description it should be held in mind what has previously been said with respect to the three natural values and, furthermore, that cos y! cos yu= cos y and that with respect to the inclination angle 7 the approximation can be made that the tangent thereof is approximately equal to its sine, since it is often unnecessary to calculate on large degrees of slope and to assume a greater degree of accuracy than this approximation affords, in order to simplify the calculating means.

The devices illustrated in FIGS. 7 and 8 are the same with respect to the connecting means and mechanical, normally manually operated adjustment means embodied therein although, as previously mentioned, the adjustment means for the values B 8,, and I B /B, have not been shown.

Each device is provided with a suitably manually adjustment 31 for the desired angle of inclination y and a similar means 32 for the desired bearing angle B, the adjustment means being in the form, for example, of wheels or small levers for rotating a resolver (R) which forms trigonometrical functions from these an gles. Furthermore, each device is provided with three inputs X, Y and Z adapted for connection to the transducer, which transmits to said inputs the measured relative values B /B B B, and B /B respectively, obtained from the transducer, said values being the control-point values and will be compared with the setpoint values in the calculating device.

In FIGS. 7 and 8, the three concentric double rings marked X, Y and Z indicate the inputs, as aforementioned. The devices are also provided with outputs A and B, the output A sending the error signal to the tilt The single line between the units indicates the electrical connections, while mechanical adjustment shafts are indicated by a double line and a curved arrow.

The output identified by the reference numeral 1 is connected to an electric signal, e.g. a fixed voltage, the signal representing the value 1 l forming in a subtraction stage, SUB, the value lcos y by applying to the subtract input of the circuit a signal corresponding to cos y.

In other respects the devices include: resolvers R, servomotors M for the resolvers, comparators in the form of arithmetical stages such as subtraction, addition and multiplication stages SUB, ADD, DIV and MULT, respectively, and a square root forming stage ROT and operation amplifiers F. The element identified with the reference -I is also an amplifier having adjusted therein an amplification factor in accordance with the inclination I.

The triangles which identify amplifiers F and I are placed so as to disclose the amplification direction, i.e. the apex of the triangle is the input and the base is the output. The arrows show the directions of propagation of the electrical signals. It should be observed that, in the absence of special standards, a triangular symbol for an amplifier is often shown inversely drawn. On the majority of the lines in FIGS. 7 and 8 have been shown the values representing the signals transmitted over the lines, while the values and directions of the signals transmitted on the remaining lines can be readily perceived, and hence a detailed description of the two Figures is unnecessary.

In those instances when the two inputs of a multiplication stop MULT are connected with each other and with a single input line, the stage will naturally operate as a squaring stage.

In those instances where two or three resolvers R are shown in the form of a double or a treble block, the angle value is transmitted mechanically between the resolvers and can be read directly from the values given on the inputs and outputs. For example, there is shown at the top of FIG. 7 a double block comprising two resolvers R, one resolver being supplied electrically with trigonometrical values of the inclination angle 7 and mechanically from the lower of the two resolvers with the angle 111 The latter resolver is fed electrically with trigonometrical values of the set desired bearing angle ,8 and mechanically with the angle 111,, between the horizontal projection of the coordinate x and the bearing ,8. The angle 41,, is thus passed from the lower of the two resolvers to the upper resolver and, moreover, the lower resolver forms the values sin(B+il1 by means of its input signals.

The calculating device illustrated in FIG. 8 differs from the device illustrated in FIG. 7 by the fact that a plurality of multiplication stages MULT of the device of FIG. 7 are omitted, while a larger number of resolvers R are used in the device of FIG. 8 than that of FIG. 7. The device illustrated in FIG. 8 employs only one multiplication step MULT designed or connected as a squaring stage. When signals representing the same values are applied to the two inputs of such a stage, the stage will naturally operate as a squaring stage.

The block diagrams illustrated in FIGS. 7 and 8 primarily relate to analogue computing devices, although the devices may be constructed tooperate either partially or optionally totally as digital computingdevices in accordance with the illustrated principle; thereby COMB-H1 0) and providing for a greater degree of accuracy, and may employ comparators in the form of arithmetical calculating stages and registers (storage elements) and also optionally trigonometrical stages (which completely or partially replace conventional resolvers) which are well known and tested in data technique and relatively inexpensive.

Resolvers exist in a ariety of constructions and need not be described here. By way'of example it can be mentioned that the resolver R provided with the adjusting member 31 and intended to convert B to lg B may simply comprise a preferably non-linear. e.g. logarithmic, potentiometer, the angular scale for adjustment of the member 31 being so graded that the potentiometer discloses a voltage proportional to tgB when 3 is adjusted in accordance with the scale.

The practical measures taken are restricted to those of manually setting the desired bearing )8 and inclination 'y whereafter the outputs A and B transmit error signals according to equation (1) and (2) to the servo-control mechanisms of the tilt and turn hydraulic units, whereby the feed beam is set to the desired position so that the bearing and inclination remain unchanged irrespective of movements of the working machine (the rock drilling unit), i.e. irrespective of the direction in which the machine is driven and the slope of the ground.

What we claim is:

1. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like; said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means, for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the vertical and the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing and angle of said seating structure to the vertical when said support unit is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing and angle of said seating structure and means responsive to the departure of said signals for pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing and angle.

2. A system according to claim 1 wherein said comparator means includes transducer means having means for sensing the actual bearing in the horizontal plane and means for sensing the actual angle in relation to the vertical.

3. A system according to the claim 2 wherein the means for sensing the actual bearing in the horizontal plane includes a course indicator mounted on said support unit and responsive to bearing directions, said course indicator providing a preset desired bearing from which all other bearings in the horizontal plane may be determined, and further comprising a second indicator mounted between said support unit and said jib means, said second indicator resistering the angle between said support unit and said jib means.

4. A system according to claim 3 wherein the means for predetermination of the desired angleto the vertical and the desired bearing includes a first selector means for selecting the desired angle and a second selector means cooperating with'said course indicator for selecting the desired bearing.

5. A system according to claim 2 wherein the means for sensing the actual bearing in the horizontal plane includes a course indicator mounted on said at least one seating structure and responsive to bearing directions.

6. A system according to claim 2 wherein the means for sensing the actual angles in the planes includes at least one pendulum means mounted on said seating structure and being active in the two planes disposed at an angle to each other.

7. A system according to claim 1 wherein the means for emitting signals responsive to the actual bearing and angle of said seating structure comprises a course and inclination transducer mounted for movement with said seating structure for producing three magnetic field signals, each of which represents three coordinate values of a coordinate system which is immovable in relation to the transducer, and corresponding to three earth field components of said coordinate system relative to a substantially fixed component of the earths magnetic field, and said comparator means compares the actual values represented by the said magnetic field signals with the values for the desired bearing and angle and transmits control signals representing departures between the actual and the desired values to drive said pivoting means for obtaining the desired bearing and angle of said seating structure.

8. A system according to claim 7 wherein said transducer contains three field component transducers, each comprising elements which are immovable with respect to each other and are immovable in relation to the seating structure and each of which produces com ponent signals which are set in relation, to the said fixed components of the earths magnetic field so that each of said signals constitutes one of said three magnetic field signals.

9. A system according to claim 8 wherein the desired angle and bearing of said seating structure can be manually adjusted and the system determines, with the assistance of said values, the inclination of the earths field, and the three said magnetic field signals, the two control signals each representing one of the values:

St gv s B 1 Sv sinyv sinyB cos #1,,

for controlling said pivoting means for the seating structure to obtain the desired movement in said two planes relative to the vertical, y! and constituting the actual angle of said seating structure, y/3 being the desired angle of the seating structure, and 41,, being the angle between the desired bearing ,8 and the horizontal projection of the coordinate axis in said coordinate system which extends forward in the direction of said jib means.

10. A system according to claim 9 wherein the desired values for the angle 7B,'-the bearing B, the said substantially fixed componentiof'the earths magnetic field and the inclination of the earths magnetic field are capable of being adjusted manually, the two last mentioned values being capableof being preset, and the inclination being adjustable by adjustment of the vertical component of the earth's magnetic field and the horizontal component to form a ratio of these tw components.

11. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means, for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said-two planes, means for predetermination of the desired angle of said seating structure with respect to the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing when said support unit or said jib means is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing, the means for sensing the actual bearing in the horizontal plane including a course indicator mountd on said at least one seating structure aand responsive to bearing directions.

12. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the vertical, means for emitting signals responsive to the angle of said seating structure to the vertical when said support unit or said jib means is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired angle of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired angle, the means for sensing the actual angles in the planes including at least one pendulum transducer mounted on said seating structure and being active in the two planes disposed at an angle to each other.

13. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the vertical and the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing and angle of said seating structure to the vertical when said support unit is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing and angle of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing and angle, the means for emitting signals responsive to the actual bearing and angle of said seating structure comprising a course and inclination transducer mounted for movement with said seating structure for producing three magnetic field signals, each of which represents three coordinate values of a coordinate system which is immovable in relation to the transducer, and corresponding to three earth field components of said coordinate system relative to a substantially fixed component of the earth's magnetic field, and said comparator means compares the actual values represented by the said magnetic field signals with the values for the desired bearing and angle and transmits control signals representing departures between the actual and the desired values to drive said pivoting means for obtaining the desired bearing and angle of said seating structure.

14. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the vertical and the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing and angle of said seating structure to the vertical when said support unit is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing and angle of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing and angle, the means for predetermination of the desired angle to the vertical and the desired bearing including a first selector means for selecting the desired angle and a second selector means cooperating with said course indicator for selecting the desired bearing, the means for emitting signals responsive to the actual bearing and angle of said seating structure comprising a course and inclination transducer mounted for movement with said seating structure for producing three magnetic field signals, each of which represents three coordinate values of a coordinate system which is immovable in relation to the transducer, and corresponding to three earth field components of said coordinate system relative to a substantially fixed component of the earths magnetic field, and said comparator means compares the actual values represented by the said magnetic field signals with the values for the desired bearing and angle and transmits control signals representing departures between the actual and the desired values to drive said pivoting means for obtaining the desired bearing and angle of said seating structure.

15. A system according to claim 14 wherein said transducer contains three field component transducers, each comprising elements which are immovable with respect to each other and are immovable in relation to the seating structure and each of which produces component signals which are set in relation to the said fixed component of the earths magnetic field so that each of said signals constitutes one of said three magnetic field signals.

16. A system according to claim 15 wherein the desired angle and bearing of said seating structure can be manually adjusted and the system determines, with the assistance of said values, the inclination of the earths field, and the three said magnetic field signals, the two control signals each representing one of the values:

Sv sin 'y v sin 'yB cos (11,,

for controlling said pivoting means for the seating structure to obtain the desired movement in said two planes relative to the vertical, yt and 'yv constituting the actual angle of said seating structure, 7,8 being the desired angle of the seating structure, and @11 being the angle between the desired bearing [3 and the horizontal projection of the coordinate axis in said coordinate system which extends forward in the direction of said jib means.

17. A system according to claim 16 wherein the desired values for the angle 75, the bearing ,8, the said substantially fixed component of the earths magnetic field and the inclination of the earths magnetic field are capable of being adjusted manually, the two last mentioned values being capable of being preset, and the inclination being adjustable by adjustment of the vertical component of the earths magnetic field and the horizontal component to form a ratio of these two components.

18. A rock drilling apparatus comprising a movable support unit, an elongated jib means pivotally mounted on said support unit, a guide seating structure, pivot means between said seating structure and said jib means providing for movement of said seating structure with respect to said jib means about first and second axes, a feed beam mounted on said seating structure, a rock drilling machine mounted for powered reciprocating movement on said feed beam, hydraulically actuated power units operably connected to said jib means and said seating structure for moving said seating structure with respect to said jib means about said first and second axes; control means including angle sensing means mounted on said seating structure for movement therewith and including gravity responsive means incorporated in said sensing means for movement with respect to said seating structure in response to gravitational forces acting on said means, signal producing means for producing signals in response to the movement of said gravity responsive means with respect to said seating structure, and a control circuit including control valves interposed therein and responsive to the signals from said signal producing means for valving hydraulic fluid to said power units'to move said seating structure about said first and second axes to maintain said feed beam and rock drilling machine in a predetermined angular direction in relation to the vertical.

the desired angle of said seating structure with respect to the vertical, comparator means for comparing the departure of said signals from the predetermined desired angle of said seating structure. and means responsive to said departure of said signals for valving hydraulic fluid to said power units for moving said. seating structure with respect to said jib means about said first and second axes.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 8 5 88 DATED July 29, 1975 INVENTOR(S) Carl Lennart Dahlstrom,et al it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

claim 1, third line from the end of claim before "pivoting" insert:

- actuating said Claim 11, next to last line spell "mounted thus last line spell and thus Signed and Sealed this fourteenth Day of October 1975 [SEAL] A ttest:

RUTH C. MASON Arresting Officer

Claims

4. A system according to claim 3 wherein the means for predetermination of the desired angle to the vertical and the desired bearing includes a first selector means for selecting the desired angle and a second selector means cooperating with said course indicator for selecting the desired bearing.

7. A system according to claim 1 wherein the means for emitting signals responsive to the actual bearing and angle of said seating structure comprises a course and inclination transducer mounted for movement with said seating structure for producing three magnetic field signals, each of which represents three coordinate values of a coordinate system which is immovable in relation to the transducer, and corresponding to three earth field components of said coordinate system relative to a substantially fixed component of the earth''s magnetic field, and said comparator means compares the actual values represented by the said magnetic field signals with the values for the desired bearing and angle and transmits control signals representing departures between the actual and the desired values to drive said pivoting means for obtaining the desired bearing and angle of said seating structure.

8. A system according to claim 7 wherein said transducer contains three field component transducers, each comprising elements which are immovable with respect to each other and are immovable in relation to the seating structure and each of which produces component signals which are set in relation, to the said fixed components of the earth''s magnetic field so that each of said signals constitutes one of said three magnetic field signals.

9. A system according to claim 8 wherein the desired angle and bearing of said seating structure can be manually adjusted and the system determines, with the assistance of said values, the inclination of the earth''s field, and the three said magnetic field signals, the two control signals each representing one of the values: St tg gamma t - tg Beta .cos psi o Sv sin gamma v - sin gamma Beta .cos psi o for controlling said pivoting means for the seating structure to obtain the desired movement in said two planes relative to the vertical, gamma t and gamma v constituting the actual angle of said seating structure, gamma Beta being the desired angle of the seating structure, and psi o being the angle between the desired bearing Beta and the horizontal projection of the coordinate axis in said coordinate system which extends forward in the direction of said jib means.

10. A system according to claim 9 wherein the desired values for the angle gamma Beta , the bearing Beta , the said substantially fixed component of the earth''s magnetic field and the inclination of the earth''s magnetic field are capable of being adjusted manually, the two last mentioned values being capable of being preset, and the inclination being adjustable by adjustment of the vertIcal component of the earth''s magnetic field and the horizontal component to form a ratio of these two components.

11. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means, for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing when said support unit or said jib means is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing, the means for sensing the actual bearing in the horizontal plane including a course indicator mountd on said at least one seating structure aand responsive to bearing directions.

13. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the vertical and the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing and angle of said seating structure to the vertical when said support unit is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing and angle of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing aNd angle, the means for emitting signals responsive to the actual bearing and angle of said seating structure comprising a course and inclination transducer mounted for movement with said seating structure for producing three magnetic field signals, each of which represents three coordinate values of a coordinate system which is immovable in relation to the transducer, and corresponding to three earth field components of said coordinate system relative to a substantially fixed component of the earth''s magnetic field, and said comparator means compares the actual values represented by the said magnetic field signals with the values for the desired bearing and angle and transmits control signals representing departures between the actual and the desired values to drive said pivoting means for obtaining the desired bearing and angle of said seating structure.

14. A system for automatically aligning at least one guide seating structure for parallel positions at different locations, said structure being adapted for guiding the movement of a tool mounted thereon as a feed beam for rock drilling machines and the like, said system comprising a movable support unit, jib means supported on said support unit, a seating structure pivotally mounted on said jib means for movement in two planes disposed at an angle to each other, means for pivoting said seating structure in each of said two planes, means for predetermination of the desired angle of said seating structure with respect to the vertical and the desired bearing of said structure with respect to the coordinates of the earth, means for emitting signals responsive to the actual bearing and angle of said seating structure to the vertical when said support unit is moved to a different location, comparator means for comparing the departure of said signals from the predetermined desired bearing and angle of said seating structure and means responsive to the departure of said signals for actuating said pivoting means in said two planes for aligning said at least one seating structure to a position parallel to the desired bearing and angle, the means for predetermination of the desired angle to the vertical and the desired bearing including a first selector means for selecting the desired angle and a second selector means cooperating with said course indicator for selecting the desired bearing, the means for emitting signals responsive to the actual bearing and angle of said seating structure comprising a course and inclination transducer mounted for movement with said seating structure for producing three magnetic field signals, each of which represents three coordinate values of a coordinate system which is immovable in relation to the transducer, and corresponding to three earth field components of said coordinate system relative to a substantially fixed component of the earth''s magnetic field, and said comparator means compares the actual values represented by the said magnetic field signals with the values for the desired bearing and angle and transmits control signals representing departures between the actual and the desired values to drive said pivoting means for obtaining the desired bearing and angle of said seating structure.

15. A system according to claim 14 wherein said transducer contains three field component transducers, each comprising elements which are immovable with respect to each other and are immovable in relation to the seating structure and each of which produces component signals which are set in relation to the said fixed component of the earth''s magnetic field so that each of said signals constitutes one of said three magnetic field signals.

16. A system according to claim 15 wherein the desired angle and bearing of said seating structure can be manually adjusted and the system determines, with the assistance of said values, the inclination of the earth''s field, and the three said magnetic field signals, the two control signals each representing one of the values: St tG gamma t - tg Beta .cos psi o Sv sin gamma v - sin gamma Beta .cos psi o for controlling said pivoting means for the seating structure to obtain the desired movement in said two planes relative to the vertical, gamma t and gamma v constituting the actual angle of said seating structure, gamma Beta being the desired angle of the seating structure, and psi o being the angle between the desired bearing Beta and the horizontal projection of the coordinate axis in said coordinate system which extends forward in the direction of said jib means.

17. A system according to claim 16 wherein the desired values for the angle gamma Beta , the bearing Beta , the said substantially fixed component of the earth''s magnetic field and the inclination of the earth''s magnetic field are capable of being adjusted manually, the two last mentioned values being capable of being preset, and the inclination being adjustable by adjustment of the vertical component of the earth''s magnetic field and the horizontal component to form a ratio of these two components.

18. A rock drilling apparatus comprising a movable support unit, an elongated jib means pivotally mounted on said support unit, a guide seating structure, pivot means between said seating structure and said jib means providing for movement of said seating structure with respect to said jib means about first and second axes, a feed beam mounted on said seating structure, a rock drilling machine mounted for powered reciprocating movement on said feed beam, hydraulically actuated power units operably connected to said jib means and said seating structure for moving said seating structure with respect to said jib means about said first and second axes; control means including angle sensing means mounted on said seating structure for movement therewith and including gravity responsive means incorporated in said sensing means for movement with respect to said seating structure in response to gravitational forces acting on said means, signal producing means for producing signals in response to the movement of said gravity responsive means with respect to said seating structure, and a control circuit including control valves interposed therein and responsive to the signals from said signal producing means for valving hydraulic fluid to said power units to move said seating structure about said first and second axes to maintain said feed beam and rock drilling machine in a predetermined angular direction in relation to the vertical.

19. A rock drilling apparatus according to claim 18 and further comprising means for maintaining the desired bearing of said seating structure with respect to said support.

20. A rock drilling apparatus according to claim 18 and further comprising means for maintaining the desired bearing of said seating structure with respect to the coordinates of the earth.

21. A rock drilling apparatus according to claim 18 and further comprising means for predetermination of the desired angle of said seating structure with respect to the vertical, comparator means for comparing the departure of said signals from the predetermined desired angle of said seating structure, and means responsive to said departure of said signals for valving hydraulic fluid to said power units for moving said seating structure with respect to said jib means about said first and second axes.