WO2023161566A1

WO2023161566A1 - Method and system for operating a forest machine

Info

Publication number: WO2023161566A1
Application number: PCT/FI2023/050114
Authority: WO
Inventors: Simo TAURIAINEN
Original assignee: Ponsse Oyj
Priority date: 2022-02-28
Filing date: 2023-02-28
Publication date: 2023-08-31
Also published as: FI20225178A1

Abstract

The invention relates to a method for operating a forest machine. In the method, a felling head (12) connected to a boom assembly (13) of the forest machine (14) is operated. A tree (10) is felled by means of a sawing (16) using the felling head (12), wherein the forest machine (14) includes a data system (19). Prior to a sawing (16), the mass distribution of the tree (10) to be felled is determined and subsequently utilized for the operation of one or more among the felling head (12), the boom assembly (13), the forest machine (14) in such a manner that the mass distribution is determined by means of the data system (19). Based on the mass distribution, the data system (19) is configured to guide or assist the operator of the forest machine (14) in the control of one or more among the felling head (12), the boom assembly (13), the forest machine (14) or to control one or more among the felling head (12), the boom assembly (13), the forest machine (14). The invention also relates to a system for operating a forest machine.

Description

METHOD AND SYSTEM FOR OPERATING A FOREST MACHINE

The invention relates to a method for operating a forest machine, wherein, in the method, a felling head connected to a boom assembly of a forest machine is operated and a tree is felled by means of a sawing using the felling head, wherein the forest machine includes a data system. The invention also relates to a system for operating a forest machine.

Modern forest machines such as harvesters are equipped with a felling head by means of which a tree is processed. In its simplest form, the felling head is only used to fell a tree by means of a sawing. In an application of the felling head with a harvester head, the tree is also delimbed and cut up into different types of timber. For cutting, the felling head includes a sawing device, which is ordinarily a chain saw, although circular saws are also used.

Both felling heads and forest machines come in different sizes. Each felling head has an operational area with which a tree can be effectively processed without compromising cost-effectiveness. However, a site can include other larger or otherwise anomalous trees whose processing requires special measures. An experienced operator can anticipate an appropriate working model by sight, but surprises can occur during processing. For example, a tree can fall in a different direction than anticipated, or it can be difficult or at the very least time-consuming to carry out the right sawing. Anomalies can also occur in subsequent processing steps. As a result, work slows down as uncertainties accumulate and a lot of energy is spent on processing. At the same time, the risk of equipment breakage, hazardous situations and even material damage increases. The object of the invention is to provide a novel method for operating a forest machine. The characteristic features of the method according to the invention are indicated in the attached patent claim 1. It is possible with the method according to the invention not only to fell a tree, but to facilitate the entire processing of the tree. At the same time, it is possible to avoid superfluous wear and breakage of equipment as well as accidents. The felling of the tree and other processing of the tree is expedited and the quality of the timber improves. A further object of the invention is to provide a novel system for operating a forest machine. The characteristic features of the system according to the invention are indicated in the attached patent claim 14. The system is easy to implement and simple to operate. The system guides and assists the driver and even performs some operations automatically. The productivity of the forest machine is improved as a consequence and the operator can concentrate on core operations. Processing of a tree is thus safe without any redundant operations.

The invention is illustrated in the following in detail with reference to the attached drawings illustrating embodiments of the invention.

Figure 1 illustrates the beginning of the felling of a tree with a forest machine,

Figure 2 illustrates a tree cut down by a forest machine at an early stage of delimbing,

Figure 3 illustrates a positioning of the felling head against a tree to be cut down,

Figure 4a illustrates an initial phase of the method according to the invention in both a side and top view,

Figure 4b illustrates an intermediate phase of the method according to the invention in the manner of Figure 4a, Figure 4c illustrates a final phase of the method according to the invention in the manner of Figure 4a,

Figure 5 illustrates an example of different sawings,

Figure 6a illustrates the first sawing of Figure 5,

Figure 6b illustrates the second sawing of Figure 5,

Figure 7a illustrates an example view of a display device,

Figure 7b illustrates another example view of the display device,

Figure 8a illustrates a pine,

Figure 8b illustrates a spruce.

Figure 1 schematically illustrates the operation of a forest machine during the harvesting of a tree. The method according to the invention relates in particular to the processing of a tree with a forest machine. In a felling sawing, a selected tree 10 growing upright in the ground is cut close to the ground surface 11, generally so as to form the shortest possible stump. An unnecessarily long stump reduces the yield and makes it difficult for forest machines to move through the forest during and after tree harvesting. Generally speaking, the method relates to the operation of a forest machine, wherein, in the method, a felling head 12 connected to a boom assembly 13 of a forest machine 14 is operated. A tree 10 is then felled by means of a sawing 16 using the felling head 12. According to the invention, prior to the sawing 16, the mass distribution of the tree 10 to be felled is determined and subsequently utilized for the operation of one or more among the felling head 12, the boom assembly 13, the forest machine 14. Different embodiments are explained in greater detail later on. When the mass distribution is known, advance preparations can be made for the processing of the tree. This makes choosing, for example, the natural felling direction easier and safer than to date. At the same time, it is possible to carry out one or more sawings for the felling easily and quickly. It is further possible to facilitate subsequent processing steps. Work safety is also improved while any damage to trees and equipment can be avoided or at the very least reduced.

In the method, a felling head 12 is operated, which is positioned at the base of the tree 10 to be felled. At the very least, the tree to be felled is cut down by means of the felling head; in the illustrated harvester embodiment, the tree is also delimbed and cut up into different types of timber. The felling head 12 is mounted on a boom assembly 13, which is attached to the forest machine 14 as illustrated in Figures 1 and 2. When felling a tree, the forest machine is generally stationary and the reach of the boom assembly is utilized to move the felling head to a desired tree and afterwards for the control of the felled tree. In Figure 1, the felling head 12 is already around the tree 10. The felling head is advantageously positioned at the felling point in a single movement so that additional positioning movements are avoided. However, when necessary, for example in heavy snow, the felling head is driven downwards in order to find a suitable sawing point. Finally, a sawing 16 is performed on the tree 10 with a sawing device 15 arranged in the felling head 12. Depending on the tree to be felled, one or more sawings are required for felling and each sawing has its own characteristics and requirements, but also its risks. Different sawings are explained in greater detail later on. In Figure 2, the tree 10 has already been cut down. Here, the felling head 12 is a harvester head which includes, in addition to the sawing device 15, delimbing knives 17 and feed rollers 18. In Figure 2, a part of the tree 10 has already been delimbed while the end of the trunk has been conveyed away from the sawing device 15. Delimbing is continued from this point until a desired log length is obtained, after which the trunk is cut with the sawing device. Delimbing and bucking operations are repeated as many times as necessary depending on the size of the tree. Some felling heads can be fitted with a so-called top saw, for example for the processing of particularly crooked trees and trees containing forks.

The mass distribution of a tree is influenced by many factors, yet can be determined with sufficient accuracy by means of a few well-chosen properties. Advantageously, a diameter 37 of the tree 10 to be felled, which is measured with the felling head 12 (Figure 3) , is used to determine the mass distribution. In practice, the diameter can be determined from closing the feed rollers 18, as the geometry of the felling head is known. An important piece of information concerning the tree, mainly its size, has thus already been obtained when felling begins. For example, when the tree is larger than usual, the felling of the tree and required sawings can be planned in advance.

The determination of the mass distribution can be readily optimized and rendered more accurate by using, in addition to the diameter 37, one or more among tree species, geographical information, forest type, trunk graph, wind, weather. Especially in the case of tree farms, the tree species to be felled is known in advance. Analogous information known in advance includes geographical information and forest type, which is mapped when planning thinning or clearcuts. A trunk graph formed beforehand, which mainly depends on the tree species and geographical information, can be used while taking the information known in advance, detection data and performed measurements such as the diameter into account. A trunk graph already provides an accurate basic idea of the type of tree in question. A trunk graph is generally based on long-term field studies including statistical data functionally dependent on tree species and geographical area, from which it is possible to determine the properties of a tree such as the mass distribution. Thus, for example, a proportion of branches and an estimated yield can be determined based on preliminary data and the diameter .

In a real tree, anomalies can be encountered such as, for example, butt swellings, tree forks or a lopsided distribution of the branches. Preliminary data formed by a measuring device 38 that can produce two- or three-dimensional images of information is also used for the determination of the mass distribution in the invention. The measuring device can be, for example, a camera, lidar or radar, or a combination of one or more measuring devices. The measuring device is advantageously mounted on the forest machine, so that the tree to be felled can be imaged when the tree is approached. In Figure 2, the measuring device 38 is a lidar device mounted on the roof of the cabin of the forest machine 14. For example, a camera can be mounted on the boom assembly or even on the felling head. Auxiliary independent measuring devices separate from the forest machine can also be used. For example, the entire tree can be imaged, right up to the canopy and from different directions, by means of a drone. This provides a comprehensive picture of the tree, which facilitates the determination of the mass distribution and other properties of the tree.

Advantageously, the mass distribution is used to determine the centre of mass 39 of the tree 10 to be felled. Figure 8a shows a pine whose branches are mainly at the top and which has a dense crown. The base part of the trunk is often branchless. The mass distribution is thus clearly different from, for example, a spruce (Figure 8b) . The centre of mass 39 of the pine here is at the top, about halfway up the trunk and slightly to one side of the trunk due to the lopsided distribution of the branches. Trees at the edges of a lot or next to strip roads receive more light, so that the branches are concentrated on the side that gets more light. In general, branches facing the south are also longer and fuller than the others, so that the mass distribution is located to one side of the trunk. A centre of mass at the top and especially to one side has a strong influence on the felling direction of the tree, which increases with oversized trees. The operational capabilities of the forest machine can thus be insufficient, which can result in unexpected situations. In spruces, the branches are usually distributed evenly and in most cases along the entire length of the trunk. In addition to properties of the tree itself, the location of the centre of mass is also influenced by prevailing conditions, or in other words by the weather. For example, the proportion of branches increases and the centre of mass rises upwards with rain or snowfall, especially in the case of pine. Wind and its direction can also surprisingly shift the point of the centre of mass in a lateral direction.

The mass distribution can be used to measure the yield of a tree or some other form of productivity of the forest machine. In the invention, the mass distribution is determined using a data system 19 of the forest machine 14 that is configured to guide or assist the operator of the forest machine 14 based on the mass distribution. In practice, the data system is fed with the aforementioned preliminary data, which is supplemented by the diameter data of the felling head and the data of other possible measuring devices. The properties of the tree are thus known with sufficient accuracy, so that the work of the operator of the forest machine 14 is rendered easier. In its simplest form, the data system guides the operator, for example by indicating the location of the centre of mass. A display device 20 connected to the data system is advantageously used for guidance (Figure 7a) . With the help of this guidance, the operator chooses, for example, the natural felling direction. In other words, the mass distribution, in particular the location of the centre of mass, is already utilized for the selection of the felling direction. In a variant, the felling direction 40, which is based on the determined mass distribution of the tree (Figure 7b) , is displayed by the data system on the display device, for example, with an arrow. In other words, the felling direction 40 of the tree is determined by means of the data system 19. The operator can thus work according to the proposed direction without analyzing the tree. This expedites the processing of the tree and trains the operator to work proficiently. Situations in which accidents occur can simultaneously be avoided, or at the very least the risk of accidents can be reduced .

In another variant, the mass distribution is determined using a data system 19 of the forest machine 14 that is configured to control one or more among the felling head 12, the boom assembly 13, the forest machine 14 based on the mass distribution. For example, by means of the guidance of the boom assembly and the felling head, the felling head can be placed at the right point at the base of the tree as well as on the right side of the tree, so that the tree falls in a chosen direction. In practice, a position and orientation of the felling head 12 relative to the forest machine 14 are determined with the data system 19 using a sensor arrangement 30 arranged on the boom assembly 13 and advantageously also on the felling head 12. By utilizing the sensor arrangement of the forest machine, it is possible for the operator to be guided in the rotation of the felling head so as to obtain the right rotation angle. On the other hand, the system can rotate the felling head automatically using the boom assembly.

The determination of a natural felling direction belongs to an initial phase in the felling of a tree, which also involves performing a sawing. Here as well, the direction of the sawing 16, which is generally different from the felling direction of the tree due to the structure of the felling head, is determined by means of the data system 19. Most felling heads include a tilt frame 41 mounted on a link, on which tilt frame 41 processing equipment such as feed rollers, delimbing knives and a sawing device are mounted as a unit. The tilt frame 41 is a U- shaped fork to which a rotator 34 is attached. The aforementioned unit is arranged in a rotatable manner in the tilt frame and rotation is controlled by one or more tilt frame cylinders (not illustrated) . At the beginning of the felling of a tree, the unit is oriented in the direction of the tilt frame, in practice vertically, as illustrated in Figure 3. The felling head 12 is positioned against the tree 10 so that the upper delimbing knife 42 rests on the surface of the tree 10 and the delimbing knives 17 and the feed rollers 18 are positioned tightly against the tree. The grip of the felling head is thus firm and the sawing can be performed safely. When the tree falls, the unit rotates with respect to the tilt frame by an angle of rotation of at least 90 degrees, usually well over 90 degrees. The fall of the tree can also be slowed down by means of the tilt frame cylinders that control the rotation of the tilt frame. The boom assembly can have a lateral tilt frame, by means of which the boom assembly can be kept vertical even if the forest machine is inclined on a slope. Figures 1 and 2 illustrate the axis of rotation 43 of the unit by means of a dash-dotted line. The axis of rotation is transverse to the tree, so that the felling head determines the felling direction. The positioning of the felling head is thus very important. The forest machine and its boom assembly are generally dimensioned so as to maintain a tree to be felled under control. For example, where necessary, the tree can thus be cut and moved in an upright position to a desired point and then allowed to fall in the direction determined by the felling head. Where necessary, the felling head can also be rotated together with the tree before the tree is allowed to fall. When oversized and lopsided trees are felled, however, the tree can still fall in an uncontrolled fashion in a random direction and cause hazardous situations and damage to equipment. These can be effectively avoided by means of the method, as the mass distribution of the tree is already taken into account during the preparation of the felling of the tree prior to the first sawing.

A sawing device 15, here a chainsaw arranged in a saw housing 21, is clearly visible in Figure 3. The saw housing is in the lower part of the unit, so that the sawing can be carried out at a low enough point. The sawing device 15 is inclined with respect to the axis of rotation of the tilt frame 41 and the difference in angle between the two is also influenced by the size of the tree. In addition, the bar of the chainsaw pivots, so that a performed sawing is arched. When a normal-sized tree is felled, a single felling sawing 28 is sufficient (Figure 5) . The tree is thus cut down by means of a single sawing and the tree falls in the direction defined by the felling head, i.e. by its axis of rotation. Other sawings can also be performed with the sawing device in connection with a felling. For example, an oversized tree or a butt swelling calls for a countercut sawing 27, wherein a sawing is performed on the tree from a different direction than the felling sawing. The tree can thus be felled even if the bar of the sawing device does not have the reach to cut down the tree in a single operation. It is possible to perform more than one counter-cut sawing. The third sawing is the undercut sawing 26, which is similar to the counter-cut sawing, but its direction is carefully chosen as a function of the desired felling direction of the tree. In practice, the undercut sawing is performed so that the edge after the sawing is parallel to the axis of rotation of the tilt frame, i.e. transverse to the felling direction. The sawing thus helps the tree to fall in the right direction and the edge of the felling sawing guides the tree to fall in the same direction as the felling head. The tree is thus felled in a controlled manner. As mentioned earlier, the wind, especially strong winds, can also have a significant influence on the direction of the felling sawing. Normal-sized trees can thus also be felled without any surprises by taking the wind into account .

A counter-cut sawing is ideally carried out at essentially the same level as the planned felling sawing. This ensures that the tree is cut down and renders the base end of the tree even. Otherwise, in cases where more than one sawing is carried out, the base end of the tree is levelled by means of a new sawing after felling. A undercut sawing, on the other hand, is performed higher up than the intended felling sawing. In practice, a centimetre or two is sufficient to form a step at the sawing point, which prevents a tree that has been cut through from dropping off the stump in the felling direction while simultaneously allowing the tree to be pulled in another direction if necessary, by which means the tree is forced to fall away from the forest machine. A potential problematic situation can be caused by an incorrectly chosen felling direction, by other erroneous operations or by an unforeseeable circumstance. These problems and surprises can be avoided, however, or at the very least accidents can be reduced, with the method according to the invention. Advantageously, the load on the felling head is reduced by means of the boom assembly by applying a small prestress to the tree. In practice, the felling head is lifted before the sawing so as to make the sawing easier. In other words, the weight of the tree is reduced against the sawing device. This prevents a jamming and breakage of the sawing device. At the same time, the sawing is still fast with no extra friction. The sawing device 15 comprises a housing 21 that is open on one side, in which a saw bar 22 is supported in a pivoting manner. The pivot point here is at the site of the axle 25 of the hydraulic motor 24 that rotates the cutting chain 23. While the cutting chain 23 rotates, the saw bar 22 is pivoted towards the tree 10, so that a sawing is formed. Depending on the situation, the sawing 16 to be performed with the sawing device is a undercut sawing26, a counter-cut sawing 27 or a felling sawing 28. Figure 5 illustrates the three different sawings. In addition, the diameter of the tree 10 is large here in relation to the sawing device, and there are butt swellings 29 at the base of the tree. A single sawing would consequently not suffice to cut down the tree. The sawing device here is a chain saw, wherein the pivot point of the pivoting saw bar of the chain saw is depicted by a circle and the path of movement of the saw bar is depicted with lines. The first is the undercut sawing 26, which is depicted by dashed lines. The undercut sawing is perpendicular to the felling direction and thus contributes to guiding the tree in the right direction. The felling direction 40 is illustrated by an arrow in Figures 6a, 6b and 7a. A tearing of the trunk base when the tree falls after the sawing is simultaneously prevented by means of the undercut sawing. In Figure 6a, a undercut sawing 26 has been performed and the tree is still upright. If necessary, more than one undercut sawing is performed one above the other so as to form a step as described above.

The second sawing is a counter-cut sawing 27, which is necessary because the saw bar does not have the reach to cut down the tree with a single sawing despite the undercut sawing. The counter-cut sawing is performed from a different side of the tree than the actual felling sawing and more than one countercut sawing can be performed. The counter-cut sawing is illustrated here by dash-dotted lines. The advantages of the method are only accentuated when a plurality of different sawings are carried out. By utilizing the data system, it is not only possible to carry out a sawing safely, but, if necessary, to carry out different sawings at essentially the same height. The cut trunk base is thus flat, so that a separate levelling sawing is not necessary. A counter-cut sawing 27 has also been performed in Figure 6b, and more than half of the tree remains. The remaining portion constitutes supporting wood that holds the tree upright and helps to guide the tree to fall in the chosen direction. If necessary, a second counter-cut sawing is carried out .

Before performing the felling sawing 28, the felling head is rotated into position, which in the case of the felling head illustrated here is approximately 90 degrees to the undercut sawing 26 (Figure 5) . The felling head and the boom assembly are thus, first of all, in a natural position with respect to the sawing and the felling direction of the tree. In addition, the saw bar has a reach to saw through the supporting wood, which forms a hinge parallel to the undercut sawing in the final phase of the felling sawing. This helps to guide the tree to fall in the chosen direction.

The aforementioned sawings are performed as required. Every unnecessary sawing consumes time and energy and subjects the sawing device to wear. In the method, the necessity of a counter-cut sawing 27 and of a undercut sawing 26 as well as, where necessary, the depth of the sawings is determined by means of the data system 19. The necessity of these sawings is also based on the mass distribution of the tree determined at the outset, upon which the method is based. If, for example, a butt swelling is detected in the determination, the data system guides the operator according to the method and even controls the forest machine and its various operations in order to perform a counter-cut sawing. In addition to the direction of the sawings, the depth of the sawings is also important. By means of the method, a counter-cut sawing of sufficient depth and a undercut sawing with a correct orientation are achieved without any superfluous sawing operations.

In a guidance mode, a final decision is made by the operator. It is thus also possible to implement a method according to the invention in which a correctness of a performed counter-cut sawing 27 and/or undercut sawing 26 is checked by means of the data system 19. Information relating to a correctness can be communicated to the operator immediately, so that a situation can often be corrected prior to the felling sawing. On the other hand, the data system can be used to check performed cuts after the fact if the tree fell differently than expected. It is thereby possible to identify potential omissions and even mistakes that were made, which can be used to improve working practices and to train the operator. Similarly, when operations are controlled by the data system, i.e. when operations are automated, it can occur that, for example, a tree falls in a direction that diverges from the chosen direction or something anomalous happens during the processing of the tree. These situations can be examined independently and changes can be made to procedures and even to the data system itself and its settings .

Sawings for felling the tree belong to an initial phase in the processing of a tree. Depending on procedures, the felling head only performs the felling and the tree is processed by other means. In this case, the method is mainly utilized for felling the tree, i.e. choosing the felling direction and performing the required sawings. On the other hand, a felling head can be used to delimb and section a tree felled by other means. Advantageously, the tree is also delimbed and cut into sections of selected lengths with the felling head. In this case, the force required to delimb the tree 10 to be felled is also determined based on the mass distribution in the method, wherein the data system 19 is configured to control one or more among the felling head 12, the boom assembly 13, the forest machine 14 based on the determined force. Based on a determination, the tree species, the centre of mass as well as the expected branch distribution are already known. The compression force of the feed rollers can first be adjusted based on the tree species and size. The location of the branches, especially in the case of pine, is simultaneously known, which makes it possible to adjust the feed rate and force of the feed rollers. For example, the feed rate can be increased before the branches occur so as to achieve a delimbing in a single operation. If necessary, the power source of the forest machine is also adjusted. If additional power is required for delimbing, power output is increased, but otherwise a steady load is ideally maintained. In other words, additional power is provided when required and not for every tree just to be on the safe side. These control operations are carried out by the data system without the need for active intervention on the part of the operator. The operator can thus concentrate on, for example, steering the boom assembly. At the same time, energy consumption is kept as low as possible and the processing of the tree flows without interruptions or re-dos.

The tree and its branch distribution are what they are; however, in order to reduce processing power requirements, mainly delimbing power requirements, one or more of the following operations is guided and/or controlled by means of the data system 19: lifting the tree 10 upwards, moving the felling head 12 with the boom assembly 13 in the delimbing direction, driving the forest machine 14 in the delimbing direction. Procedures that allow power requirements to be reduced or processing to be otherwise facilitated are suggested to the operator by the guidance system. In a control mode, the data system operates actively and takes selected measures such as increasing the power output of the forest machine in a suitable manner before delimbing. Procedures can also be implemented simultaneously, so that overall operation is smooth. At the same time, the number of control commands to be performed by the operator is reduced, so that the operator can concentrate on the essentials without an excessive workload.

The invention also relates to a system for operating a forest machine. The system includes a felling head 12 connected to a boom assembly 13 of a forest machine 14. In addition, a sawing device 15 is arranged on the felling head 12 for performing a sawing 16 on a tree 10 in order to fell the tree 10. The forest machine 14 also includes a data system 20. In the invention, the data system 19 is configured to determine, prior to a sawing 16, a mass distribution of the tree 10 to be felled, which the data system 19 is configured to utilize for the operation of one or more among the felling head 12, the boom assembly 13, the forest machine 14. Moreover, the system is configured to implement one or more steps of the method described in the foregoing. In other words, the system can be operated in accordance with the method and its different sub-steps. The system can be implemented using software provided that the necessary sensor arrangements, measuring devices and the data system are installed on the forest machine.

In Figure 3, the felling head 12 is behind the tree 10 and the sawing device 15 is visible. Due to the geometry of the felling head and of the forest machine as a whole, however, a felling head in a natural felling orientation is usually in a different position than in Figure 3. In other words, the felling head is on a different side of the tree, so that the sawing device may be hidden from view. The position and even the grip of the felling head can be modified before being, under the guidance or control of the data system, placed in a natural direction with respect to the felling direction or the sawing direction. The felling head is rotated around the tree between different sawings .

Figures 4a to 4c illustrate a sawing device 15, the orientation of which affects the different sawings. In Figure 4a, the felling head with the sawing device 15 is brought towards the tree 10. Preliminary data regarding the tree to be felled can be collected at the same time. For example, the felling head can include a measuring device by means of which it is possible to detect a butt swelling. The left side of the figures shows a tree in a side view and the right side shows the tree in a top view. In Figure 4b, the operator sees the sawing device 15 and can place the felling head against the tree 10 for a sawing. The felling head is then rotated, for example, to a side of the tree according to a natural felling direction, and the sawing is performed. If the felling direction or sawing direction is known when the head is brought to the tree, the felling head can be placed directly in the correct position. When the sawing device is visible as illustrated in Figure 4b, the felling head can be placed at an appropriate height in order to avoid that the sawing device hits the ground or a rock near the tree. In the situation illustrated in Figure 4c, the sawing device 15 has a reach that can cut down the tree 10 with a single sawing, so that the only cut required is the felling sawing. The method is also of great benefit in this situation, as the felling head is placed deliberately in the felling orientation, which is predetermined based on the mass distribution of the tree.

In a homogeneously planted and thinned-out tree farm, the trees are mainly alike in terms of their mass distribution, so that, for example, the felling direction can be assumed based on previous trees. However, the system is also able to assess each tree, so that the analysis and subsequent processing of each tree is individualized. Unexpected tree-specific anomalies are simultaneously detected and thus taken into account.

Advantageously, the system utilizes a sensor arrangement 30, which is arranged on the boom assembly 13 of the forest machine 14. In Figure 1, the sensor arrangement 30 is arranged at the end of the boom assembly and the sensor arrangement 30 includes one or more 3D acceleration sensors 31. The sensors are located as close as possible to the felling head 12. In addition, an accuracy of the sensor arrangement is sufficient when the forest machine remains stationary during sawings. The 3D acceleration sensor 31 is connected here by a cable 32 to the data system 19 of the forest machine 14, to which data system 19 a display unit 20 is also connected. The sensor arrangement used for the determination of the orientation of the felling head, such as, for example, the mentioned 3D acceleration sensor, can also be wirelessly connected to the data system of the forest machine 14. Generally speaking, the positions and orientations of the boom assembly and its parts are known by means of the sensor arrangement, so that the positions and orientations of the felling head in relation to the forest machine are also known. The sensor arrangement can also include sensing means for determining the angles of articulation of the boom assembly and thus for determining the height position of the sawing device. Instead of or in addition to 3D acceleration sensors, sensor devices can include rotation sensors, position sensors and/or cylinder-piston position sensors. In addition, the sensor arrangement can also include sensing means employed to determine the speed and state of motion of the end of the boom assembly/f elling head, for example a 3D angular speed sensor in addition to the 3D acceleration sensors. The display unit displays information to the operator regarding, for example, the forest machine itself and work productivity, as well as, for example, a map program. The display device can also have buttons for performing selections and settings. A tactile functionality is also possible. The display device is also utilized in the method, as, for example, the location of the centre of mass 39 or the felling direction is advantageously displayed graphically on the display device 20, which is configured as part of the data system 19 of the forest machine 14. Figure 7a schematically illustrates a display device 20 showing a tree 10 as well as a centre of mass of the tree determined by the data system 19. In Figure 7b, the felling direction 40 is indicated by an arrow in the view. Guided by the view, an operator can control the felling head until the felling head accords with a desired felling direction. Depending on the case, it can be necessary to perform different sawings for which the system can also be utilized as described earlier on. In addition to statistical entries, it is also possible to display animations on the display device which guide and steer the operator. For example, an optimal rotation direction for the next sawing can be shown on the display device in the form of an animated arrow. The method makes it possible to speed up operations by eliminating a positioning of the felling head by sight alone.

In the method, the sensor arrangement 30 of the forest machine 14 can determine a respective rotation angle 33 of the felling head 12, based on which different sawings 16 can be aligned with other potential sawings. The alignment here relates to the respective rotation angles, i.e. the positions of the felling head on different sides of the tree. For example, the rotation angle of the undercut sawing illustrated in Figure 5 can be stored in the data system as a kind of origin. The position of the felling head when performing other sawings can thus be compared to this reference point. Even after a plurality of counter-cut sawings, the felling head can thereby be accurately rotated into a orientation that is natural for the felling sawing and especially for felling and that is consonant with the determination made. In the forest machine of the Applicant, the difference between rotation angles is 90 degrees; however, depending on the manufacturer, the difference can be some other value, which can be taken into account when programming the data system. Advantageously, the rotation angle 33 is also displayed graphically on the display device 20, which is configured to be part of the data system 19 of the forest machine. The rotation angle 33 is also shown in the view of the display device 20 illustrated in Figure 7b. In order to determine the rotation angle, a detector 35 of the sensor arrangement 30 is arranged on the rotator 34 in the embodiment shown in Figure 1, by means of which detector 35 the rotation angle of the felling head is monitored. The detector 35 is also connected by the cable 32 to the data system 19.

The rotation angle can be utilized analogously for a countercut sawing. More specifically, as the position of the felling head during the counter-cut sawing is known by means of the sensor arrangement, the position into which the felling head has to be rotated for the felling sawing is known. In practice, the felling head is rotated in this case from the counter-cut sawing in such a manner that the felling sawing is formed at the side exactly opposite. The remaining tree is of uniform thickness, which is important for a successful felling as well as for the strength of the supporting wood. Similarly, when the rotation angle of the rotator as well as the position into which the felling head must be rotated after the first sawing is known, the counter-cut sawing function can be automated or at least semi-automated in order to speed up work and improve both quality and accuracy.

The method and the system are especially advantageous for controlling counter-cut sawings of large diameters, in particular butt swellings, and the felling sawing itself, as well as for the further processing of the tree. The method and system are especially easy to implement in forest machines, such as harvesters, equipped with a boom-tip-control system, in which an extensive sensor arrangement is already implemented. The boomtip-control system facilitates the work of the operator, since the operator steers the felling head in a desired direction while the boom-tip-control system controls the cylinders of the boom assembly in order to bring about the desired movement without it being necessary for the operator to control the individual cylinders. In addition to sawings, the sensor arrangement can also be effectively utilized to control different actuators for delimbing.

The boom assembly 13 is attached to the forest machine 14 by a base support 36. A tip-controlled boom assembly knows its own position in relation to its base support and consequently also in relation to the forest machine. In the invention, it is possible to exploit a control system of a tip-controlled boom assembly of a forest machine to a considerable degree. A control system of a tip-controlled boom assembly can comprise at least one measuring device or measuring device arrangement in order to determine the orientation of at least one boom part of the boom assembly of the forest machine. The orientation of said at least one structural part of the boom assembly comprises a determination of at least the angle of inclination of the structural part in the direction of at least one axis of the boom part with respect to a reference direction, such as the direction of the gravity vector, and/or with respect to a reference point. Advantageously, the reference point is the base machine of the forest machine and/or the point of attachment of the boom assembly to the forest machine. Advantageously, each boom part of the boom assembly is equipped with a measuring device in order to determine the orientation of said boom part. On the other hand, it is also possible with the invention to utilize measuring devices arranged in connection with a conventional boom assembly of a forest machine, which are configured to determine the orientation and/or the state of motion of at least one structural part of the boom assembly. In the invention, the control system and/or the measuring device arrangement of the forest machine is configured to measure the orientation and/or state of motion of the boom assembly and/or of individual boom parts of the boom assembly of the forest machine, as well as the orientation, rotation angle and/or state of motion of the felling head. Advantageously, said control system is configured to automatically detect the orientation and/or the rotation angle of the felling head of the boom assembly of the forest machine by detecting the orientation and/or the state of motion of the individual boom parts.

Sturdy tree trunks, especially in the case of spruce, often have wide butt swellings, so that it ends up being necessary to perform as many as three or four counter-cut sawings. The counter-cut sawings are carried out on different sides of the tree, so that it is not always possible to see from the cabin exactly how the felling head is positioned. The data system provides assistance, thereby rendering operations easier and faster. Some procedures can even be automated in the data system .

In the invention, positioning is understood to mean the movement of the felling head in general, for example, in relation to a tree. An alignment in the context of sawings means that the direction from which the sawing is performed can be aligned with the directions of other sawings. The direction of other potential sawings is then aligned according to the previous sawing with the guidance of the display device or by means of software.

Claims

1. Method for operating a forest machine, wherein, in the method, a felling head (12) connected to a boom assembly (13) of the forest machine (14) is operated and a tree (10) is felled by means of a sawing (16) using the felling head (12) , wherein the forest machine (14) includes a data system (19) , characterized in that, prior to the sawing (16) , a mass distribution of the tree (10) to be felled is determined and subsequently utilized for the operation of one or more among the felling head (12) , the boom assembly (13) , the forest machine (14) in such a manner that the mass distribution is determined using a data system (19) , which, based on the mass distribution, is configured to

- guide or assist the operator of the forest machine (14) in the control of one or more among the felling head (12) , the boom assembly (13) , the forest machine (14) , or

- control one or more among the felling head (12) , the boom assembly (13) , the forest machine (14) .

2. Method according to claim 1, characterized in that a diameter (37) of a tree (10) to be felled, which is measured by means of the felling head (12) , is used to determine the mass distribution.

3. Method according to claim 2, characterized in that, in addition to the diameter (37) , one or more among tree species, geographical information, forest type, trunk graph, wind, weather is used for the determination.

4. Method according to any of claims 1 to 3, character-

that can produce two- or three-dimensional images of information is used for the determination.

5. Method according to any of claims 1 to 4, character- ized in that a centre of gravity (39) of a tree (10) to be felled is determined from the mass distribution.

6. Method according to any of claims 1 to 5, characterized in that the position and orientation of the felling head (12) relative to the forest machine (14) are determined with the data system (19) using a sensor arrangement (30) arranged on the boom assembly (13) and/or on the felling head (12) .

7. Method according to any of claims 1 to 6, character- ized in that a felling direction (40) of the tree is determined by means of the data system (19) .

8. Method according to any of claims 1 to 7, character- ized in that a direction of a sawing (16) is determined by means of the data system (19) , wherein the sawing is a undercut sawing (26) , a counter-cut sawing (27) or a felling sawing (28) .

9. Method according to any of claims 1 - 8, characterized in that a necessity for and, if necessary, a depth of a countercut sawing (27) or undercut sawing (26) is determined by means of the data system (19) .

10. Method according to claim 9, characterized in that a correctness of a performed counter-cut sawing (27) and/or undercut sawing (26) is checked by means of the data system (19) .

11. Method according to any of claims 1 to 10, characterized in that a force required to delimb a tree (10) to be felled is determined based on the mass distribution, wherein the data system (19) is configured to control one or more among the felling head (12) , the boom assembly (13) , the forest machine (14) based on the determined force.

12. Method according to claim 11, characterized in that, in order to reduce power requirements, one or more of the following operations is guided and/or controlled by means of the data system (19) : lifting the tree (10) upwards, moving the felling head (12) with the boom assembly (13) in the delimbing direction, driving the forest machine (14) in the delimbing direction .

13. Method according to any of claims 1 to 12, character- ized in that a load on the felling head (12) is reduced by means of the boom assembly (14) prior to a sawing (16) by lifting .

14. System for operating a forest machine, wherein the system includes a felling head (12) connected to a boom assembly (13) of the forest machine (14) and a sawing device (15) arranged on the felling head (12) for performing a sawing (16) on a tree (10) in order to fell the tree (10) , wherein the forest machine (14) includes a data system (19) , characterized in that the data system (19) is configured to determine, prior to a sawing (16) , a mass distribution of the tree (10) to be felled, which the data system (19) is configured to utilize for the operation of one or more among the felling head (12) , the boom assembly (13) , the forest machine (14) in such a manner that the data system (19) , which, based on the mass distribution, is configured to

15. System according to claim 14, characterized in that the system is configured to execute a step of the method according to any of claims 2 to 13.