EP1989393A1

EP1989393A1 - Method and device for controlling the drilling direction of a rock drilling rig

Info

Publication number: EP1989393A1
Application number: EP07709381A
Authority: EP
Inventors: Johan Larsson
Original assignee: Atlas Copco Rock Drills AB
Current assignee: Epiroc Rock Drills AB
Priority date: 2006-02-28
Filing date: 2007-02-26
Publication date: 2008-11-12
Anticipated expiration: 2027-02-26
Also published as: CA2642614A1; SE0600437L; WO2007100284A1; SE529623C2; CA2642614C; EP1989393B1; EP1989393A4; NO20084113L; NO338266B1

Abstract

The present invention relates to a rock-drilling rig comprising at least one boom having a first end and a second end and a drilling machine arranged at said boom, wherein said first end is attached to a carrier, and wherein said drilling machine is attached to said other end by means of a first joint means and a second joint means, wherein said joint means are arranged to be manoeuvred by an operator by means of control means for controlling the drilling direction of said drilling machine, The rock-drilling rig comprises means for determining a rotation of said second joint means on the basis of the rotation position of said first joint means in such a manner that the influence of said joint means on the movement of said drilling machine corresponds to a direction indicated by the operator using said control means. The invention also relates to a device and a method.

Description

Method and device for controlling the drilling direction of a rock-drilling rig

Field of the invention

The present invention relates to a method and device for controlling the drilling direction of a rock-drilling rig.

Background of the invention

In rock-drilling in general and in tunnel drilling in particular, a rock-drilling rig is often used in which one or more drilling machines are supported by respective movable arms, so called booms. The booms are usually articulately fastened to a carrier, such as a vehicle, by one or more joints. Furthermore, the respective drilling machine is articulately fastened by one or more additional joints to that end of the respective boom which is facing away from the carrier. The drilling machine is usually fastened not directly to the boom, but via a feeder along which the drilling machine can be transported during drilling.

Usually, a construction is used in which the boom is fastened to the carrier in such a way that the boom is movable about two joints, and in which manoeuvring about these two joints, for example, can be realized by a tripod construction having two hydraulic cylinders disposed substantially parallel with the boom, which are fastened to the carrier below, and laterally displaced in each respective direction, relative to the fastening point of the boom, to allow raising/lowering and lateral rotation of the boom. In order to realize the motion of the feeder relative to the other end of the boom, a corresponding construction is used, yet in which the front cylinders are oppositely disposed, i.e. fastened to the top side of the boom. In this way, a constant load direction upon the constituent components is obtained, which has the advantage that any play within the joints has no or only slight impact upon the boom. In front of the front joint, furthermore, there is disposed a rotation joint, with which the feeder can be rotated about the longitudinal axis of the boom. Moreover, a feeder tilt joint is usually present, with which the feeder can be angled upwards/downwards . This double tripod construction, however, has the disadvantage that the front tripod is space requiring and heavy, which results in limitations of boom length and boom rigidity due to torque restrictions at the point of the fastening of the boom to the carrier. In order to overcome these problems, a boom construction has therefore been produced, wherein the front tripod is exchanged for rotation joints. The advantage with this construction is that the rotation joints reduce the weight at the outer end of the boom, which in turn means that a both longer and stiffer boom can be used. Moreover, the mobility of the feeder is increased.

The double tripod solution has the rotation unit disposed in front of the front tripod, with the result that a natural relationship between control stick (such as a joystick or control ball) motion and feeder motion is obtained in all situations if the two dimensions of the control stick are directly connected to the two joints of the front tripod. For example, a forward motion of the control stick can be arranged to always result in the feeder tip (the end of the feeder facing the rock during drilling) being directed downwards since the forward-backward motion of the control stick is always connected to the feeder tilt joint.

With regard to a boom having rotation joints in stead of a front tripod, however, the reaction of the feeder in relation to manoeuvring of the control stick will vary in dependence of the position of the feeder in relation to the boom, which results in undesired effects during drilling. Accordingly, a need for an improved rock-drilling rig exists.

Summary of the invention

It is an object of the present invention is to provide a device for feeder direction control at a rock-drilling rig, which solves the above problem.

This and other objects are achieved according to the present invention by a rock-drilling rig as defined in claim 1, a method as defined in claim 8 and a device as defined in claim 15.

According to the present invention, a device for feeder direction control at a rock-drilling rig is provided, wherein said rock-drilling rig comprises a boom having a first end and a second end , and a drilling machine arranged at the said boom, wherein said first end is fastened to a carrier and wherein said drilling machine is fastened to said carrier by means of said boom and said other end by means of at least a first joint member and a second joint member, wherein said joint members are arranged to be manoeuvred by an operator by means of control means for controlling the drilling direction of said drilling machine. The device comprises means for reading the rotation position of said first joint means, means for reading control signals from the operator by means of said control means, and means for determining a rotation of said second joint means based on the rotation position of said first joint means in such a way that the influence of said joint means on the motion of said drilling machine corresponds to a direction indicated by said operator using said control means . This has the advantage that instead of connecting the respective dimension of the control stick against a specific physical joint, the position of the control stick is instead used as a reference of the direction in which the operator wants the drilling machine to move, and then a suitable movement for said second joint is calculated based on said first joint. The motions of the control stick is accordingly released from the connection to a specific joint according to the prior art and is, instead, connected to "virtual" joints which act just as if the control stick dimensions were directly coupled to physical joints. Said first and/or second and/or third joint means can be constituted by rotation joint means such as a rotator comprising a rotation motor. This has the advantage that the present invention is applicable on joint means by means of which a large freedom of motion can be obtained. Brief description of the drawings

Fig. 1 discloses a boom for a rock-drilling rig wherein the control stick can be coupled directly against specific joint means .

Fig. 2 discloses a boom for a rock-drilling rig wherein a direct coupling of the dimensions of the control stick against physical joint means result in undesired effects.

Fig 3 shows a thread model for a boom according to fig 2.

Fig. 4 shows the boom of fig. 2, wherein the feeder has been rotated to another position. Fig. 5 shows a flow chart of an exemplary method according to the present invention.

Detailed description of preferred embodiments

In Fig. 1, a rock-drilling rig 1 is shown. The rock-drilling rig 1 comprises a boom 2, one end 2a of which is fastened to a carrier 10, such as a vehicle 10, and at the other end 2b of which there is disposed a feeder 3 supporting a drilling machine 4. The drilling machine 4 is displaceable along the feeder 3. The rock-drilling rig 1 can further be remote- controlled by an operator via a control device which is connected to the rock-drilling rig 1 by means of a cable (not shown) and in which control means in the form of, for example, one or more control sticks (such as joysticks or track balls) can be used to control the drilling direction of the drilling machine 4. The control device can also be wirelessly connected to the rock-drilling rig. Alternatively, the rock-drilling rig can be controlled by an operator located in a cab (not shown) disposed on the carrier/vehicle 10. The shown rock-drilling rig is depicted as only comprising one drilling boom, but can comprise two, three, four or more drilling booms, each boom supporting a respective drilling machine.

As previously mentioned, the boom(s) 2 is/are usually articulated fastened to the carrier 10 by one or more joints. In Fig. 1, these joints are constituted by a tripod construction, in which two hydraulic cylinders 6, 7 are fastened to the carrier 10 somewhat below and laterally displaced relative to the point of attachment of the boom, so that the three points of attachment form the shape of a triangle in which the points of attachment of the hydraulic cylinders 6, 7 define the base of the triangle. The other ends of the hydraulic cylinders 6, 7 are fastened to the bottom side of the boom 2. Control of the cylinders β, 7 allows the boom 2 to be raised/lowered and guided in the lateral direction. Usually, the said control device is provided with a separate control stick for this purpose, in which the boom 2 is raised/lowered by moving the control stick backwards/forwards. In the same way, the boom is guided to the right/left by moving the control stick to the right/left. Accordingly, there is a direct coupling between the two dimensions of the control stick and the two joints of the boom motion.

Furthermore, the drilling machine 4 is articulately fastened to that end 2b of the boom 2 which is facing away from the vehicle by a correspondingly working device having two cylinders 8, 9, which are fastened to the top side of the boom and then, in corresponding manner to the cylinders 6, 7, in the shape of a tripod with the apex, i.e. the attachment of the boom, downwards. With the aid of the cylinders 8, 9, therefore, the feeder 3, and hence the drilling machine 4, can be angled forwards/backwards and rotated about an axis running transversely to the longitudinal axis of the drilling boom. In other words, the feeder can constantly be kept parallel, at the same time as the boom is raised/lowered and/or turned to the right/left. The feeder can also be turned in the lateral direction with the aid of the cylinders 8, 9. Furthermore, the feeder with drilling machine can be rotated about the said tripod attachment by means of a rotation joint 11. Moreover, a feeder tilt joint 12 is present, which is used to angle the feeder about its fastening point. In this case also, the dimensions of a control stick can be directly coupled against the feeder tilt joint and feeder swing, respectively, by means of cylinders 8, 9. Accordingly, an operator will always be familiar with the manner in which the feeder will behave for any control stick position. This will also be true when the feeder is rotated using the rotational joint 11, since the axis of this joint is also influenced by the movement of the cylinders 8, 9. Therfore, when using this conventional boom 2, it is a simple task for an operator to control the direction of the feeder, and thereby the direction of the drilling machine 4, so that drilling in a desired direction can be performed.

As was previously mentioned, however, this boom has a plurality of disadvantages. In particular, the front tripod is space requiring and heavy, which is why the boom 22 shown in fig. 2 has been developed, which with regard to the fastening of the boom 22 to the carrier 10 is functioning in the same manner as the boom in fig. 1, with a tripod functioning in the same manner, having hydraulic cylinders 27, 28, wherein the motion of the boom up/down and laterally can be controlled entirely according to the above. With regard to the front tripod and rotational joint 11, however, these have been exchanged for two rotation joints 23 (feeder rotation), 24 (feeder swing) , which together with 25 (feeder tilt) can be used to provide the same or better possibilities to control the feeder in different directions, and thereby replaces the front tripod (hydraulic cylinders 8, 9), rotational joint 11 and hydraulic cylinder joint 12. The rotation joints 23, 24 are, in this embodiment, arranged substantially at right angles in relation to each other, wherein the rotation joint 23 is fastened to the boom 22 and thereby allows rotation about the longitudinal axis of the boom 22. Rotation by means of rotation joint 23 therefore results in the feeder being rotated about the longitudinal axis of the boom. The rotation joint 24 is arranged at a right angle with respect to the rotation joint 23, and thereby allows rotation of the feeder about a, in relation to the boom, transversal axis. Further, the feeder can be rotated about a feeder tilt joint 25 in the same manner as in fig. 1. In fig. 3 is shown a link model for the boom disclosed in fig. 2. As can be seen, and according to the above, the boom comprises five degrees of freedom with regard to rotation, wherein Zl is constituting boom swing, Z2 boom lift, Z4 feeder rotation, Z5 feeder swing and Z6 feeder tilt. Furthermore, the disclosed boom comprises a degree of freedom with regard to translation Z3, i.e., the boom can be prolonged/shortened in a telescopical manner. Further, there is an additional degree of freedom with regard to translation Z7, since the feeder usually can be displaced relative to the boom. With regard to the drilling machine, this can also be displaceable in relation to the boom. The use of a displaceable feeder and/or drilling machine, has the result that the feeder must not continuously be moved forward as the drilling progresses. When the feeder is in a position as shown in fig. 2 a backwardly directed motion of the control stick will, when the dimensions of a control means (e.g. a control stick) are directly connected to the rotation joint 24 and feeder tilt joint 25, result in the feeder being rotated about the feeder tilt joint 25 in such a manner that the feeder tip 2βa move in the direction of arrow A. Furthermore, a movement of the control stick to the right (left) will, just as before, result in a corresponding movement of the feeder tip 26a to the right (left) by rotation of the rotation joint 24. Therefore, in this case also, a direct connection between the dimensions of the control stick and the rotation joint 24 and feeder tilt 25, respectively, could be used. If, however, the feeder is in a position such as shown in fig. 4, i.e., the feeder 26 has been rotated 180° by means of the rotational joint 23, the position of the control stick will result in directly opposite reactions of the feeder tilt 26a. For example, a manoeuvre to the right using the control stick will result in the feeder tip 26a moving to the left. In a corresponding manner the feeder tip 26a will, when the control stick is moved backwards, move in the direction of arrow B. Consequently, the feeder, (feeder tip) will, in this position, behave in a completely other manner than what is expected by the operator, which can result in undesired consequences.

Furthermore, if the feeder has been rotated to a position in between the positions shown in fig. 2 and 4, respectively, by means of the rotation joint 23, effects of the control stick influence on the feeder, which are really difficult to master, will result, with the result that an operator being familiar with drilling using a boom of the kind shown in fig. 1, will receive even more unusual effects for practiced control stick movements. This has as result that the operator cannot switch from a machine having the one boom type to a machine having the other boom type without "learning" how the machine behaves at various control stick positions. This is not desired since feeder movements (and thereby drilling) takes longer time, and there is a risk of damaging drilling machine or other equipment if the feeder is moving in another direction than what is intended.

The present invention solves this problem by, instead of connecting the respective dimension of the control stick to a specific physical joint, using the position of the control stick as a reference for the direction in which the operator wishes the feeder to move, and then calculate a suitable movement for the rotational joint 24 and feeder tilt joint 25. Accordingly, this means that the movement of the control stick is disengaged from the connection to a specific joint and is instead connected to "virtual" joints.

An example of the manner in which the calculation of the movement for the rotation joint 24 and feeder tilt joint 25 can be carried out will now be described for the boom disclosed in fig. 2. The example will be described with reference to the flow chart in fig. 5. In step 501, control signals from the operator of the rock-drilling rig is read, the control signals can be generated using a control means, e.g. a control stick such as a joystick, a control ball, a track pad or manoeuvre buttons, and for example constitute a two-dimensional direction indicator (lifting or lowering the feeder tilt at the same time as manoeuvring it to the right or the left) . In step 502, the various rotation positions of the boom joints are read, i.e., rotation position of boom swing, boom lift, feeder rotation, feeder swing and feeder tilt. The rock-drilling rig is, in a conventional manner, provided with sensors for detecting the various rotation positions of the joints. Therefore, the reading of the positions will not be described more in detail herein. After reading the positions of the boom joints, the turned position p₀ of the feeder is, in step 503, calculated in the coordinate system according to fig 3. This calculation can be carried out using standardized coordination transformations and the read (angular) positions of the boom joints.

In step 504, the direction vector p₀ is rotated about the coordinate axes x, y, z according to the control signal from the operator. The rotation can be carried out in various manners, e.g., the rotation of the direction vector p₀ about the coordinate axes can be carried out in various orders . Consequently, what is stated below merely constitutes an exemplary method of obtaining a desired result. The corresponding result can also be obtained in a plurality of other ways. Further, the functions can be varied based on a manner in which the signal from control means desirably should influence the change in direction of the feeder, e.g., whether movement of the control stick forwards is to raise or lower the feeder tip. In the calculations, the following variables are used: Po = original direction vector of the feeder rotX = angle for rotation about the Z-axis

rotY = angle for rotation about the Y-axis

RotZ = angle for rotation about the Z-axis

Xi, Yi = signal from control means

t = direction vector after rotations corresponding to a desired change in direction of the feeder has been applied to

The signal from the control means can, apart from including an indication of a direction, also be determined in magnitude in order to indicate the desired speed of the change in direction. The size of the signal should, however, be adapted to limitations of motions speeds of those joints that are to be controlled for accomplishing a desired change in direction. The control means can also be arranged such that when, for example, it is constituted by a control stick, the control stick can be of a non-springback type, so that the control stick can be set to a certain position, which then represent the direction into which the feeder is to be directed. I.e., instead of using the control stick to set a desired motion direction of the feeder, the final direction into which the feeder is to be directed is set instead. For example, in the neutral position of the control stick, the feeder can, for example, be arranged to be set as horizontal and parallel to the boom or to the longitudinal axis of the carrier.

The rotational angles can be calculated according to the following : rotX = sign (poz) *Poz²* (-yi) +sign (poy²* (-Xi) , wherein sign stands for the sign.

rotY = (Po_x ² + Poz²)*xi

rotZ = (pox² + poy²) *γ±

The direction vector t of the feeder in the coordinate system shown in fig. 3 can then be calculated as: Ry,rotγ, Rχ,rotχPo, wherein R_n,_m constitutes the rotational matrix for a rotation about an axis by the angle m. Rotation matrixes are well described in literature and will therefore not be described further here.

In the next step (505), the movements of the feeder swing (FS) joint and feeder tilt (FT) joint are calculated. This is performed using the following equations, wherein the following abbreviations are used:

BS₀ = read angle for boom swing before change in direction BL₀ = read angle for boom lift before change in direction FR₀ = read angle for feeder rotation before change in direction FS₀ = read angle for feeder swing before change in direction FT₀ = read angle for feeder tilt before change in direction FS_rotatedΛ FTrotated = calculated angle for feeder swing and feeder tilt, respectively, in order for the direction of the feeder to correspond to the desired direction according to the direction vector t.

FTrotated can be calculated as

FT_rotated = -arcsin (B) ,

wherein B can be calculated as:

B = t_x(sin (BS₀) *sin (FR₀) + cos (BS₀) *cos (FR₀) *sin (BL₀) ) + t_z*cos (BL₀) *cos (FR₀) - t_y (cos (BS₀) *sin (FR₀) -

cos (FR₀) *sin(BS₀) *sin(BL₀) )

Furhter, FS_rotated can be obtained as

FSrotated = arctan (C/A) ,

wherein A and C can be calculated as:

A = t_x*cos (BS₀) *cos (BL₀) - t_z*sin (BL₀) + t_y*cos (BL₀) *sin (BS₀)

C = -t_x(cos (FR₀) *sin(BS₀) - cos (BS₀) *sin (BL₀) *sin (FR₀) ) +

t_z*cos (BL₀) *sin (FR₀) + t_y (cos (BS₀) *cos (FR₀) +

sin (BS₀) *sin (BL₀) *sin (FR₀) )

As is appreciated by a person skilled in the art, this results in a plurality of possible solutions for FS_rotated and FT_rotated. From these solutions, those angles of FS_rotated and FT_rotated being closest to the original angles of FS₀ and FT₀, respectively, are selected. Further, the above equations are specific for the boom shown in fig. 2. These equations will, of course, look different for other kinds of booms having other joint configurations .

In conclusion, the movements of feeder swing and feeder tilt can be calculated as FS_rotated - FS₀ and FT_rotated - FT₀, respectively, provided that the input signals have been adapted to limitations in motion speeds of the joints concerned. The above method is finalised in step 506 by carrying out the calculated movements.

Controlling the joints in this manner, allows that a device that can be arranged to behave similar to the boom shown in fig. 1 can be obtained as a result. Thereby, an operator can change from drilling with booms according to fig. 1 to drilling with booms according to fig. 2 without any difference in the behaviour of the feeder. The present invention can, therefore, be said to provide virtual joints for feeder swing and feeder tilt which corresponds to the dimensions of the control stick and which ensure that the feeder, and thereby the drilling machine, moves exactly as in the operators mind, which is important in order to be able to position the drill bit, i.e. feeder, into a correct position and correct angular direction in relation to the rock in order to produce the desired hole. This is particularly important when positioning for drilling contour holes during tunnel drilling, i.e. the outermost row of holes. These holes often all have different directions, and require that feeder and drilling machine are positioned very close to the surrounding rock.

In the above description, the invention has been described for a specific configuration of various joints. The invention, however, can also be used in other types of booms, wherein the described phenomenon occurs. For example, the boom can be fixedly fastened to the carrier. In this case there is no boom lift or boom swing, and these parameters can, in this case, be reduced from the above equations or be replaced by constants. Further, other kinds of joints can be used, e.g. the second rotation joint and feeder tilt joint can be replaced by a spherical joint, wherein calculation of a movement of the spherical joint can be calculated based on the position of the first rotation joint, wherein the above equations are adjusted in accordance therewith. Alternatively, the two rotation joints described above and the feeder tilt joint can be exchanged with one or more spherical joints, or, alternatively, more than two rotation joints, wherein the above equations in a similar manner are adjusted in accordance therewith .

As is appreciated by the person skilled in the art the present invention can, of course, also be used in a boom wherein the rear tripod also, or instead of, the front tripod has been exchanged for rotation joints, in which case motions are calculated for both the front and rear joints.

Further, instead of the above described tripod construction, a solution in which the boom at the carrier is movable using a cylinder working substantially in parallel to the longitudinal axis of the boom for raising/lowering the boom, and a cylinder working substantially transversal to said longitudinal axis, can be used.

Claims

C L A I M S

1. Rock-drilling rig (1) comprising at least one boom (22) having a first end and a second end and a drilling machine arranged at said boom (22), wherein said first end is attached to a carrier (10) , and wherein said drilling machine is attached to said other end by means of a first joint means (23) and a second joint means (24), wherein said joint means (23, 24) are arranged to be manoeuvred by an operator by means of control means for controlling the drilling direction of said drilling machine, characterized in that the rock- drilling rig comprises means for determining a rotation of said second joint means (24) on the basis of the rotation position of said first joint means (23) in such a manner that the influence of said joint means (23, 24) on the movement of said drilling machine corresponds to a direction indicated by the operator using said control means.

2. Rock-drilling rig according to claim 1, characterized in that said drilling machine, apart from said first and second joint means (23, 24) further is attached to said boom by means of at least third joint means (25), wherein the rock-drilling rig further comprises means for determining a rotation of said third joint means (25) on the basis of the rotation position of said first joint means (23) in such a manner that the influence of said joint means (23, 24, 25) on the movement of said drilling machine corresponds to a direction indicated by the operator using said control means.

3 . Rock-drilling rig according to claim 1 or 2 , c h a r a c t e r i z e d i n t h a t said first ( 23 ) and/or second (24) and/or third (25) joint means is/are constituted by rotation joint means.

4 . Rock-drilling rig according to claim 3 , c h a r a c t e r i z e d i n t h a t said first ( 23 ) and/or second (24) and/or third (25) joint means is/are constituted by a rotator comprising a rotation motor.

5. Rock-drilling rig according to any of the preceding claims, characterized in that said drilling machine is arranged to be attached to boom (22) by means of a feeder (26), and wherein said joint means (23, 24, 25) influence the direction of said feeder (26) .

6. Rock-drilling rig according to any of the claims 1-5, characterized in that said boom (22) further is attached to the carrier (10) by means of at least fourth joint means (27, 28), wherein said rotation of said second (24) and/or third (25) joint means are arranged to also be determined on the basis of the rotation position of said fourth (27, 28) joint means.

7. Rock-drilling rig according to any of the preceding claims, characterized in that the said direction given by the control means consists of a two-dimensional direction .

8. Method for controlling feeder direction at a rock-drilling rig (1), wherein said rock-drilling rig (1) comprises a boom (22) having a first end and a second end and a drilling machine arranged at said boom, wherein said first end is attached to a carrier (10), and wherein said drilling machine is attached to said carrier (10) by means of the other end of the boom (22) by means of at least a first joint means (23) and a second joint means (24), wherein said joint means (23, 24) are arranged to be manoeuvred by an operator using control means for controlling the drilling direction of said drilling machine, characterized in that the method comprises the steps of:

- reading (502) the rotation position of said first joint means (23) ,

reading (501) control signals from the operator by means of said control means,

determining (505) a rotation for said second joint means (24) on the basis of the rotation position of said first joint means (23) in such a manner that the influence of said joint means (23, 24) on the movement of said drilling machine corresponds to a direction indicated by the operator using said control means.

9. Method according to claim 8, wherein said drilling machine, apart from said first and second joint means (23, 24) further is attached to said boom by means of at least a third joint means (25), wherein the method further comprises the step of determining a rotation for said third joint means (25) on the basis of the rotation position of said first joint means (23) in such a manner that the influence of said joint means (23, 24, 25) on the movement of said drilling machine corresponds to a direction indicated by the operator using said control means .

10. Method according to claim 8 or 9, wherein said first (23) and/or second (24) and/or third (25) joint means are constituted by rotation joint means.

11. Method according to claims 10, characterized in that said first (23) and/or second (24) and/or third (25) joint means are constituted by a rotator comprising a rotation motor .

12. Method according to any of the claims 8-11, wherein said drilling machine is arranged to be attached to said boom by means of a feeder (26), and wherein said joint means (23, 24, 25) influence the direction of said feeder (26) .

13. Method according to any of the claims 8-12, wherein said boom (22) further is attached to the carrier by means of at least a fourth joint means (27, 28), wherein said rotation of said second (24) and/or third (25) joint means is also determined on the basis of the rotation position of said fourth joint means (27, 28) .

14. Method according to any of the claims 8-13, wherein said direction indicated by means of the control means consists of a two-dimensional direction.

15. Device for a controlling a feeder direction at a rock- drilling rig, wherein said rock-drilling rig (1) comprises a boom (22), having a first end and a second end and a drilling machine arranged at said boom, wherein said first end is arranged to be attached to a carrier (10) and wherein said drilling machine is arranged to be attached to said carrier (10) by means of the other end of said boom (22) by means of at least a first joint means (23) and a second joint means (24), wherein said joint means (23, 24) are arranged to be manoeuvred by an operator using control means for controlling the drilling direction of said drilling machine, characterized in that the device comprises :

means for reading the rotation position of said first joint means, means for reading control signals from the operator by means of said control means,

means for determining a rotation of said second joint means (24) on the basis of the rotation position of said first joint means (23) in such a manner that the influence of said first joint means (23, 24) on the movement of said drilling machine corresponds to a direction given by the operator using said control means .