BACKGROUND

The invention relates to working machines, and more particularly to determining a condition of a structural part of a working machine.

lnspecting a condition of a working machine using the known methods has typically required clean, controlled environment and special equipment. Therefore, it has often been necessary to transport the working machine to a spe cific maintenance site for checking condition, such as changes in clearances and gaps in joints due to wear, of the working machine. This has meant breaks in the production, which has led to less frequent inspections to avoid maintenance breaks and financial losses. On the other hand, the less frequent inspection in crease the risk of unplanned breakdowns.

BRIEF DESCRIPTION

An objective of the present invention is thus to provide a new method, arrangement, working machine and computer program product. The object is achieved by a method, arrangement, working machine and computer program product characterized by what is stated in the independent claims. Some pre ferred embodiments are disclosed in the dependent claims.

The invention is based on the idea of comparing an actual position or state of motion of a structural part of the working machine to a computational position or state of motion of the structural part to determine a condition of a working machine. More particularly, a computation position or state of motion is determined on the basis of a computational model, of the working machine and an actual position or state of motion is determined on the basis of information received from detecting means, and the condition is determined on the basis of the difference between the actual position or state of motion and the computa tional position or state of motion.

An advantage of the method and arrangement is that it enables deter mining the condition of the working machine practically anywhere, such as on site, and even during normal working cycle and with equipment already provided in the working machine for other purposes. This enables avoiding or minimizing maintenance breaks for this measurement purpose and, on the other hand, more frequent determining of the condition. Thereby, wear can be detected as early as possible and necessary maintenance breaks for replacing spare parts and similar can be planned well ahead. This also means that different maintenance tasks can be combined to minimize the number of maintenance breaks and risks of un planned breaks caused by worn and/or broken parts and even risks of injury caused by them can be minimized. BR1EF DESCRIPTION OF THE DRAWINGS

ln the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 illustrates a working machine;

Figure 2 illustrates a method for determining a condition of at least one structural part of a working machine;

Figure 3 illustrates an arrangement 1 for determining a condition of at least one structural part of a working machine;

Figure 4 illustrates schematically a first structural part and a second structural part of a working machine;

Figure 5 illustrates an embodiment of a working machine;

Figure 6 illustrates schematically a boom of a working machine; and

Figure 7 illustrates schematically an embodiment of a working ma chine and a difference between a computational position or state of motion and an actual position or state of motion of a boom of the working machine.

DETA1LED DESCRIPTION

A working machine may comprise any working machine comprising structural parts 11, such as a first structural part 11’ and a second structural part 11". According to an embodiment, a first structural part 11’ and a second struc- tural part 11" may be connected to one another directly or indirectly. The first and second structural part 11’, 11" being connected directly refers to the first structural part and the second structural part being connected to one another without any intermediate part or structure. The first and second structural part being connected indirectly refers to the first structural part and the second struc- tural part being connected to one another by means of one or several other parts and/or structures, such as at least one joint, actuator, bearing, gear, connector and/or fastener.

ln embodiments, where the first structural part and the second struc tural part are connected either directly or indirectly, the movement of the first structural part 11’ and the second structural part 11" may be limited in at least one direction of movement. The direction of movement, in which the movement is limited, may be translational or rotational. According to an embodiment, the mu tual movement of the first structural part and the second structural part may be limited in more than one translational and/or rotational direction of movement. The limitation may refer to the movement being completely prevented or the movement being controlled, for instance via an actuator, gear or other suitable means.

According to an embodiment, the movement of the first structural part 1G and the second structural part 11" with respect to one another in at least one direction of movement may be limited completely, whereby the first structural part and the second structural part are connected to one another fixedly in this direction of movement.

According to an embodiment, the movement of the first structural part ll’and the second structural part 11" with respect to one another in at least one direction of movement may be limited partly, whereby the movement of the first structural part with respect to the second structural part is enabled but limited in magnitude. Depending on the direction of movement in question, the magnitude may comprise a maximum angle, a maximum distance, a maximum velocity or maximum angular acceleration of the allowed mutual movement.

According to an embodiment, the first structural part 11’ may be con nected to the second structural part 11" by a form lock. The form lock refers to the first structural part and the second structural part or another other part or structure connecting the first structural part to the second structural part com prising a form and a counter form that, when provided against one another, limit the mutual movement of the first and the second structural parts in at least one direction of movement.

According to an embodiment, the working machine may comprise a mobile working machine. This is beneficial, as mobile working machines are typi cally used in environments that are not optimal for traditional ways of inspecting conditions, such as wear, gaps, clearances, deformations, distortions and/or cracks, of the working machine structural parts and joints, and/or remotely from maintenance sites and equipment. According to an embodiment, the working ma chine 10 may comprise a forest machine. This is particularly beneficial, as forest machines are typically used far away from maintenance sites and equipment and in conditions particularly challenging for traditional methods of inspecting wear, gaps, clearances, deformations, distortions and/or cracks and other similar condi- tions of the working machine 10. A deformation can be elastic or plastic.

Figure 1 illustrates a working machine 10. The work machine in Fig ure 1 is a forest machine, more particularly a forwarder. However, the present solution is applicable for other types working machines, like other types of forest machines, such as harvesters, as well as mobile working machines and other types of working machines too, like lifting machines, timber transporters and other types of machines or vehicles equipped with booms or other types of work implements, like the mining or construction machines, and the forwarder is shown to illustrate typical structural parts and principles of a (mobile) working machine only.

A working machine 10 may comprise one, two or more frame parts 4. A working machine may also comprise a cabin 12 arranged in at least one of the frame parts 4. Furthermore, a working machine 10, more particularly a mobile working machine, may comprise moving equipment 13. The moving equipment 13 may comprise at least one of the following: wheels, continuous tracks and oth er moving elements for moving a working machine with respect to ground or oth er working platform known as such. According to an embodiment, the working machine 10 may also comprise a boom 14. ln the embodiment of Figure 1, the working machine 10 further comprises other structural parts 11, such as a load space 15, a tool (not shown), such as a harvester head or a grapple, and a power source 17. lt is clear for a person skilled in the art that all the parts and equipment of the working machine 10 mentioned may be considered as structural parts 11 of the working machine, as well as any other structural parts of the working ma chine 10 not mentioned particularly.

Figure 2 illustrates a method of determining a condition of at least one structural part 11 of a working machine 10. The method may comprise determin ing 203 a computational position or state of motion of the first structural part 11’ on the basis of the computational model of the working machine. The computa tional position or state of motion of the first structural part 11’ refers to the in- tended position or state of motion, in which the first structural part 11’ should be provided on the basis of the computational model of the working machine, for instance the intended position or state of motion, in which the first structural part 11’ should be provided on the basis of the computational model of the working machine as a result of controlling position or state of motion of the first structural part, such as controlling the first structural part 11’ of the working machine to move, stay in place or maintain its current state of motion. The computational position or state of motion is, thus, determined by data processing means, such as by data processing means 23 of the control system 2 and/or data processing equipment external to the working machine 10, on the basis of the computational model of the working machine without actual measurements directed to the first structural part 11’ at the time of the determination of the computational position or state of motion.

The data processing means may, for instance, be configured to retrieve the computational model from a memory, such as a memory of the working ma chine, a memory of the terminal device or a memory provided at a remote loca- tion, and execute product program code provided on a computer readable medi um to determine the computational position or state of motion of the first struc tural part 11’ and/or to determine the condition of at least one structural part of the working machine.

The computational model may comprise for instance a design model or a model built on the basis of measurements made during intended use of the working machine, while the condition of the structural parts has been known to be adequate.

According to an embodiment, the method comprises controlling the position or state of motion of the first structural part 11’. The position or state of motion of the first structural part may be controlled relative to a second structur al part 11" of the working machine and/or relative to the surroundings of the working machine 10, such as the ground.

According to an embodiment, the first structural part 11’ may be con trolled to maintain its current position and/or state of motion ln other words, the first structural part 11’ may be controlled to stay in place or maintain its current state of motion. According to another embodiment, controlling the position or state of motion of the first structural part may comprise arranging the first struc tural part 11’ of the working machine to move. The first structural part 11’ may arranged to move relative to a second structural part 11" of the working machine and/or relative to the surroundings of the working machine 10, such as the ground and/or the gravity vector. The gravity vector refers to an acceleration vector caused by gravity, shown by arrow D in Figure 5.

The first structural part 11’ may be controlled to move for instance in response to providing a control command, such as a command to move, provided by a control system 2 of the working machine. Similarly, the first structural part 11’ may be controlled to maintain its position or state of motion either by a con- trol command or absence of a (new) control command. The control command may be based on an operator using a user interface 3 and/or an automatic control provided by the control system controlling the operation of the working machine 10. According to an embodiment, the operator and/or the control system may control the working machine 10 remotely via remote connection, such as a tele connection. According to an embodiment, the control system may provide such an automatic control as a part of a work cycle of the working machine 10. ln other words, one, multiple or all of the method steps may be executed in the working machine, in a remote location, and/or in a terminal device provided in the work- ing machine, in the vicinity of the working machine and/or in a location remote from the working machine, for example. The steps may also be distributed be tween different devices, such that some of the data and/or equipment is provided in a first device, such as the working machine, and some of the data and/or equipment is provided in a second device. The control system 2 may comprise data processing means 23. The data processing means 23 may comprise a control ler and/or a data processor.

According to an embodiment, the computational position or state of motion of the first structural part 11’ on the basis of the computational model of the working machine may comprise the intended position or state of motion of the first structural part 11’, in which the first structural part 11’ should be pro vided in response to the control command provided by the control system 2 con sidering a start position or state of motion of the first structural part 11’, the con trol command provided by the control system 2 and the computational model of the working machine. The computational model of the working machine refers to a model created using an engineering tool, such as a CAD, 3D CAD or CAE tool or similar, and comprising information about the geometries, kinetics and other sim ilar characteristics of the working machine 10. According to an embodiment, the computational model comprises information about at least one of the following: a geometry of the working machine, a weight of at least one structural part of the working machine, and a kinetic model of the working machine. A kinetic model of the working machine may comprise, among other things, information about di mensions, physical properties, material characteristics and information about the way the structural parts are arranged in relation to one another, as well as infor mation about elasticity and/or deformation of structural parts, actuator, or hy- draulic components.

According to an embodiment, the computational position or state of motion of the first structural part 1G and the actual position or state of motion of the first structural part 1G may be determined relative to a predetermined coor dinate system. According to another embodiment, the computational position or state of motion of the first structural part 1G and the actual position or state of motion of the first structural part 1G may be determined relative to a start posi tion or state of motion of the first structural part 1G. The start position or state of motion refers to the position or state of motion of the first structural part 1G be fore the control of the first structural part 1G, such as the control to move the first structural part 1G.

The method may further comprise determining 205 an actual position of the first structural part 1G by detecting means 22. The actual position or state of motion of the first structural part 1G refers to the actual position or state of motion the first structural part 1G is provided at the time of the determination, for instance as a result of controlling position or state of motion of the first struc- tural part, such as controlling the first structural part 1G of the working machine to move, to stay in place or maintain its current state of motion. The actual posi tion or state of motion is, thus, determined on the basis of data received from the detecting means 22 at the time of the arranged movement or after the arranged movement has taken place. According to an embodiment, the detecting means 22 may comprise at least one detector. According to an embodiment, the detecting means may comprise at least one of the following: an inclinometer, an accelera tion sensor, an angular acceleration sensor, a gyroscope, an inertial measurement unit, a joint angle sensor, a linear position meter, an angular position meter, a po sition sensor of a pressure medium sensor, such as a position sensor of a hydrau- lie cylinder, a radar and an optical sensor, such as a LiDAR (Light Detection and Ranging) or camera. The actual position or state of motion of the first structural part 1G may be determined by detecting means 22 for instance by sensing, meas uring and/or calculating the position or state of motion. According to an embodi ment, the data processing means 23 may also be involved in the determining of the actual position or state of motion.

The actual and computational position of the first structural part 1G may comprise for instance a location and/or orientation of the first structural part 1G. The actual and/or computational state of motion of the first structural part 1G may comprise for instance the velocity, the acceleration, angular velocity and/or angular acceleration of the first structural part. Depending on the embod iment, the actual position or state of motion and the computational position or state of motion of the first structural part 1G may be determined relative to a second structural part 11" of the working machine, relative to the surroundings of the working machine 10, such as the ground and/or the gravity vector, relative to the start position or state of motion of the first structural part 11’ before the arranged movement, and/or relative to a predetermined coordinate system.

The method may further comprise determining 207 the condition of the at least one structural part 11 on the basis of the difference between the com putational position or state of motion of the first structural part 11’ and the actual position or state of motion of the first structural part 11’. ln other words, the con- dition may be determined on the basis of the actual position or state of motion of the first structural part 11’ being different than the computational position or state of motion of the first structural part 11’. This is based on conditions, such as wear, gaps, clearances, deformations, distortions and/or cracks in the first struc tural part 11’, the second structural part 11” and/or a structural part 16 connect- ing the first and second structural parts 11’, 11" to one another causing the first structural part 11’ being provided in an actual position or state of motion differ ent from the intended position or state of motion, in other words the computa tional position or state of motion.

According to an embodiment, the condition of the at least one struc- tural part 11 may be determined by a one-time measurement, in other words by measuring the actual position or state of motion of the first structural part 11’ at a given time instant after an arranged movement of the first structural part 11’, calculating the computational position or state of motion of the first structural part 11’ on the basis of the computational model and comparing these positions or states of motion ln such an embodiment, the condition of the at least one structural part 11 may be determined to be acceptable, if the difference between the actual position or state of motion and the computation position or state of motion of the first structural part 11’ is within a predetermined threshold. Simi larly, the condition may be determined to trigger at least an action, if the differ- ence between the actual position or state of motion and the computation position or state of motion of the first structural part 11’ exceeds a predetermined thresh old.

According to further embodiment, the condition of the at least one structural part 11 may be determined repeatedly, either occasionally or regularly. This enables comparing values of the difference between the actual position or state of motion and the computation position or state of motion of the first struc- tural part 11’ at different time instants to find an increase or decrease in the val ues reflecting the condition of the at least one structural part 11. This is beneficial, as systematic errors in the measurements can be detected and filtered from the results and threshold values and trends can be used to detect changes in the con- dition over time. According to an embodiment, the difference between the actual position or state of motion and the computation position or state of motion of the first structural part 11’ may be determined at least at one and preferably at least at two of the following time instants: when a new working machine is taken into use, after maintenance of the working machine, at the beginning of a new work shift and at a predetermined time interval from at least one of the previously mentioned time instants.

According to an embodiment, the condition may be determined auto matically. ln other words, the control system 2 may determine the at least one time instant at which the condition is determined. According to another embodi- ment, the condition may be determined in response to an action of the operator, such as in response to the operator initiating the determination of the condition using the user interface 3.

According to an embodiment, the control system 2 may be arranged to trigger an action in response to at least one criteria for the condition being ful- filled. Such a criteria may comprise for instance setting a control limit, such as a threshold, for the difference between the actual position or state of motion and the computation position or state of motion of the first structural part 11’. Ex ceeding the predetermined threshold and/or a trend of the difference between the actual position or state of motion and the computation position or state of motion of the first structural part 11’ determined from a plurality of time instants meeting a predetermined criteria, such as a predetermined number of decreasing or increasing values or other similar criteria known in the art, may be arranged to trigger an action. According to an embodiment, the action triggered may comprise at least one of the following: providing an alert to the operator, for instance on a display or as an audio alert, affecting the operation of the working machine by the control system 2, for instance slowing down the process, limiting or inhibiting some functions, extreme positions and/or loads handled to prevent hazards caused to the operator, the working machine, the material being processed and/or the working environment, or even stopping the working machine in case of increased risks.

The condition may be determined for the first structural part 11’, a second structural part 11", or a structural part 16 connecting the first and second structural parts 11’, 11" to one another. Each of the first structural part 11’ and the second structural part 11" may comprise at least one of the following or a part thereof: a frame part 11, a cabin 12, a piece of moving equipment 13, a boom 14, a boom section, a load space 15, a tool and a power source 17. Each of the first structural part 11’ and the second structural part 11" may also comprise in addi tion to or instead of the above mentioned structural parts any other structural part of the working machine 10 known as such.

According to an embodiment, the first structural 11’ part may be ar- ranged to move by moving means 5, such as at least one actuator (not shown) of the working machine 10. Actuators for moving structural parts of working ma chines are well known in the art and may comprise, for instance, a hydraulic actu ator, a pneumatic actuator, an electric actuator or an actuator driven by any other suitable manner. The actuator may comprise for instance a motor or a pressure fluid cylinder. According to a further embodiment, the moving means 5, such as an actuator, may be external to the working machine and, thus, be driven by a power source external to the working machine 10. ln some embodiments, the first structural part 11’ may not comprise moving means at all. Such a first structural part 11’ may or may not be designed, for instance articulated, to move relative to other structural part(s) of the working machine.

According to an embodiment, the computational position or state of motion, the actual position or state of motion of the first structural part 11’ may be determined relative to a second structural part 11”. ln such an embodiment, the first structural part 11’, the second structural part 11" or both structural parts may be provided with detecting means 22. According to a further embodiment, the detecting means 22 may be provided in a further structural part 11 of the working machine other that the first or the second structural part, for instance if the detecting means 22 comprise a distance detecting sensor, such as a radar or an optical sensor.

The computational and/or actual position or state of motion of the first structural part 11’ relative to the second structural part 11" may then be de termined either by directly determining the mutual position or state of motion of the structural parts, for instance by a detector detecting a distance and/or an an gle between the structural parts, or by determining the actual positions or states of motion of both structural parts 11’, 11” and determining the position or state of motion of the first structural part 11’ relative to the second structural part 11" on the basis of the determined positions or states of motion of the structural parts 11’, 11”.

According to an embodiment, a start position or state of motion of the first structural part 11’ relative to the second structural part 11" may be used as a reference position or state of motion. The actual position or state of motion of the first structural part 11’ relative to the second structural part 11" after the move ment may be determined with respect to that reference position or state of mo tion, or by detecting the change in the actual position or state of motion of the first structural part 11’ relative to second structural part 11" in some other way known as such, such as by a sensor sensing a change in a distance or angle be tween the first and second structural parts 11’, 11". Similarly, the computational position or state of motion of the first structural part 11’ may be determined rela tive to the reference position or state of motion, in other words the start position or state of motion of the first structural part 11’ relative to the second structural part 11".

The position or state of motion of the first structural part 11’ with re spect to the second structural part 11" refers to mutual translational and/or rota tional position or state of motion of the first and second structural parts 11’, 11”. ln other words, one or both of the first and second structural parts 11’, 11" may rotate or move in a translational direction with respect to the other.

ln other words, in the method, arrangement, working machine and/or computer program product of this description a first structural part 11’ of a work ing machine 10 is arranged to move and the computational position or state of motion and the actual position or state of motion of the first structural part 11’ after the movement are determined. The condition of at least one structural part 11’, 11”, 16 of the working machine 10 is then determined on the basis of the dif ference between the actual position or state of motion and the computational po sition or state of motion of the first structural part 11’.

According to an embodiment, the condition is determined for the first structural part 11’. ln other words, in the method, arrangement and computer program product, the condition of the structural part for which the computational position or state of motion and the actual position or state of motion are deter mined, may be determined. According to another embodiment, in the method, arrangement and computer program product, the condition is determined for a second structural part 11" that is different from but arranged in connection with the first structural part 11’. Depending on the embodiment, the first structural part 11’ and the second structural part 11" may be connected directly or indirect ly, as explained above. According to a further embodiment, the condition is de termined for a structural part 16 connecting at least two structural parts of the working machine, the first structural part 11’ and the second structural part 11".

According to an embodiment, the condition is determined for a joint connecting at least two structural parts 11, 11’, 11”, 16 of the working machine. According to an embodiment, the first structural part 11’ may comprise the joint. According to another embodiment, the first structural part 11’ may comprise at least one of the structural parts 11, 11’, 11”, 16 connected to one another by the joint.

According to an embodiment, the condition of the at least one struc tural part 11’, 11”, 16 may comprise wear of the structural part. According to an embodiment, the wear of the at least one structural part 11’, 11”, 16 may com prise change in the clearance or gap in the connection between the first and the second structural parts 11’, 11".

According to an embodiment, determining the condition of at least one structural part may comprise determining at least one of the following: a clear ance of a structural part, a clearance of a joint of two structural parts, a de formation of a structural part, a deformation of a joint of two structural parts, a flex of at least one structural part, a crack in at least one structural part and a leakage of a structural part.

A clearance or a gap may comprise for instance an axial bearing clear ance, an actuator clearance, a transmission clearance and/or a mechanical clear ance. The axial bearing clearance may comprise for instance a clearance in a joint or a telescopic mechanism. The actuator clearance may comprise for instance clearance in the actuator mounting means, for instance in the dimension of a mounting bracket, or a clearance in the dimensions of the actuator itself. The transmission clearance may comprise for instance a clearance in dimensions of a toothed transmission or other type of form-based transmission device. The me- chanical clearance may comprise for instance a clearance in dimensions of a lock ing mechanism or mounting mechanism.

A leakage may comprise a leakage of pressure medium via a seal, a damaged hose, a damaged pressure medium line, a valve or other component of the pressure medium system, the wear, deterioration or failure of which may cause a leakage affecting the operation of the first structural part 11’.

Figure 6 illustrates schematically a boom of a working machine. Fig- ure 6 also illustrates a joint 8, more particularly two joints 8, and different types of clearance or gap in connection with such a joint. Figure 6 illustrates the direc tions of a radial clearance 51 and axial clearance 52. Figure 6 also illustrates an embodiment of providing detecting means 22 in at least two structural parts 11, more particularly in three structural parts 11. ln such an embodiment, either one of the structural parts 11 provided with the detecting means 22 may comprise the first structural part 11’, and one of the other structural parts 11 may comprise the second structural part 11”. The detecting means 22 may comprise an inertia sen sor, for example. The inertia sensor may comprise for instance an inertia meas- urement unit, for example lnertia Measurement Unit made by MEMS-technology. The detecting means 22 may also comprise some other type of detecting means disclosed in this description.

According to an embodiment, the actual position or state of motion of the first structural part 11’ may be determined directly, for instance relative to working platform or to the ground, the gravity vector or a predetermined coordi nate system. According to another embodiment, the actual position or state of motion of the first structural part 11’ may be determined relative to a second structural parts 11".

According to an embodiment, the actual position or state of motion of the first structural part 11’ may be determined by determining at least in one di rection of measurement at least two different measured variables, a first and a second measured variable; receiving a first and a second measurement signal de scribing the first and the second measured variable in data processing means; and determining the actual position or state of motion of the first structural part on the basis of the first and the second measured variable.

Determining at least the two different measured variables for a direc tion of measurement and for a structural part enables using average values from the measurements and/or measurement errors occurring in a single measured variable and caused by various disturbances to be compensated for quickly and accurately ln such a case, by combining the signals of the acceleration sensor and/or an inclinometer and/or the angular velocity sensor and/or the angular acceleration sensor in order to compensate for the measurement errors it is pos sible to calculate the actual position or state of motion of the structural part in a reliable manner. Such compensation is known per se and thus does not need to be explained in closer detail herein. The use of these detectors provides for instance the advantage that the position or state of motion information may be determined by small, inexpensive, reliable and long-lasting detectors, which may often also be arranged quite freely in the structural part being monitored ln comparison with the present solutions, durable articulation angle sensors and linear position sen sors, for instance, are expensive.

According to an embodiment, the actual position or state of motion of the first structural part 1G is determined by at least one of the following: an incli nometer, an acceleration sensor, an angular acceleration sensor, a gyroscope, a magnetometer, a capacitive distance sensor, an inertial measurement unit, a line ar position meter, an angular position meter, a joint angle sensor, a position sen- sor of a pressure medium sensor, such as a position sensor of a hydraulic cylinder, a radar and an optical sensor, such as a LiDAR (Light Detection and Ranging) or camera.

According to an embodiment, the first and/or the second measure ment signal may comprise at least one of the signals of the following: an inclinom- eter, an acceleration sensor, an angular acceleration sensor, a gyroscope, a mag netometer, a capacitive distance sensor, an inertial measurement unit, a linear position meter, an angular position meter, a joint angle sensor, a position sensor of a pressure medium sensor, such as a position sensor of a hydraulic cylinder, a radar and an optical sensor, such as a LiDAR (Light Detection and Ranging) or camera.

According to an embodiment, a predetermined time interval for de termining the condition of the at least one structural part may be set.

According to an embodiment, the condition of the at least one struc tural part 1G, 11", 16 may be determined automatically during normal use of the working machine 10, for instance at the predetermined time interval. This is par ticularly beneficial, as the normal use of the working machine does not need to be interrupted and no active actions are needed from the operator of the working machine. This makes it easier to continuously monitor the condition of the work ing machine and enables detecting early signs of wear, for example, giving more time and alternatives for planning maintenance actions ln such an embodiment, the determination of the condition of at least one structural part may be imple mented in connection with movements that belong to the normal use, for instance normal work cycles, of the working machine 10. ln other words movements of the first structural part 11’ related to implementing other functions of the working machine, may be used for determining the condition of the at least one structural part. According to another embodiment, data processing means of the working machine may be arranged to give an alert or a reminder to the operator at prede termined time intervals to determine the condition. Depending on the embodi ment, the operator may comprise for instance an owner, a maintenance person, a driver or a manager of the working machine.

According to an embodiment, the determining of the computational position or state of motion, the actual position or state of motion and the condi tion of at least one structural part may be made during testing and/or normal production use of the working machine, for instance continuously or at prede termined time intervals lf for instance a boom or crane moves, such as swings or moves downwards, while no control command has been given for the working machine to move the boom or the crane, especially if this movement exceeds a predetermined threshold, the condition of for instance the boom, a joint of the boom or the hydraulic system controlling the boom may be determined to be de teriorated.

According to an embodiment, the actual position or state of motion of the first structural part 1G may be determined to correlate with the computa tional position or state of motion according to the computational model. On the basis of this information, the condition of at least one structural part, such as the first structural part 1G, a joint connecting the first structural part 1G to a second structural part 11" or some other structural part of the working machine may be determined to be adequate.

According to an embodiment, the actual position or state of motion of the first structural part 11’ may be determined to differ from the computational position or state of motion according to the computational model an amount ex- ceeding a predetermined threshold. On the basis of this information, the condition of at least one structural part, such as the first structural part 11’, a joint connect ing the first structural part 11’ to a second structural part 11" or some other structural part of the working machine may be determined to be inadequate ln other words, the difference between the actual and computational position or state of motion may be interpreted to indicate an unideal state of the structural part, the condition of which is being determined, and the difference exceeding a predetermined limit value may be determined to indicate a condition of the struc tural part triggering an action.

For instance, a control command may be given for the first structural part 11’ to move to a certain direction, but the actual position or state of motion of the first structural part 11’, such as the position or the velocity of the first structural part IV, may not correlate to the computational position or state of motion of the first structural part 1G.

Or a toothed transmission, driven for instance by a cylinder, may be controlled to move the first structural part 1G, but the position or state of motion of the first structural part 1G, in other words the actual position or state of mo tion of the first structural part 1G, may be determined to be different from the computational position or state of motion, such as a computational velocity or orientation of the first structural part 1G. For instance, the actual position or state of motion of the first structural part 1G may be determined by the detecting means to be maintained the same, although the cylinder is detected to start mov ing and/or a movement of the first structural part 1G may be determined to con tinue while it is controlled to maintain its position. On the basis of this infor mation, it may be determined that the condition of the toothed transmission is deteriorated. This may comprise for instance a tooth of the toothed transmission being deformed or a clearance changed due to wear or similar.

According to an embodiment, such action triggered by the determined condition of the structural part may comprise giving a notification for the opera tor, providing a sound or visual alarm, slowing down or stopping the movement of the structural part or some other structural part or function of the working machine, preventing the movement and/or use of the working machine altogeth er. According to an embodiment, several limit values or thresholds may be prede termined correlating to conditions of different severity, whereby the action se lected to be triggered may be determined to depend on the severity, such as the magnitude of the difference between the actual and computational position or state of motion.

Figure 3 illustrates an arrangement 1 for determining a condition of at least one structural part 1G, 11”, 16 of a working machine 10.

The arrangement 1 may comprise moving means 5 arranged to move a first structural part 11’ of the working machine. The position or state of motion of the first structural part 11’ may be controlled. According to an embodiment, the first structural part 11’ may be controlled to maintain its current position or state of motion and according to another embodiment the first structural part 11’ may controlled to move relative to a second structural part 11" of the working ma chine and/or relative to the surroundings of the working machine 10, such as the ground and/or the gravity vector. The first structural part 11’ may be controlled, for instance controlled to move, for instance in response to providing a control command provided by a control system 2 of the working machine, or in the case of maintaining its position or state of motion possibly also in response to the ab sence of a control command. The control command may be based on an operator using a user interface 3 and/or an automatic control provided by the control sys- tern controlling the operation of the working machine 10. According to an embod iment, the operator and/or the control system may control the working machine 10 remotely via remote connection, such as a teleconnection. According to an em bodiment, the control system may provide such an automatic control as a part of a work cycle of the working machine 10. The control system 2 may comprise data processing means 23.

The arrangement 1 may further comprise detecting means 22 ar ranged to determine an actual position or state of motion of the first structural part 11’. The actual position or state of motion of the first structural part 11’ is explained in more detail in connection with the description related to the method of Figure 2.

The arrangement 1 may further comprise data processing means 23 arranged to determine a computational position or state of motion of the first structural part 11’ on the basis of the computational model of the working ma chine. According to an embodiment, the data processing means 23 may comprise data processing means of a control system 2, such as a control system of the working machine 10. The computational position or state of motion of the first structural part 11’ and the computational model of the working machine are ex plained in more detail in connection with the description related to the method of Figure 2.

The data processing means 23 may further be arranged to determine the condition of the at least one structural part on the basis of the difference be tween the computational position or state of motion of the first structural part and the actual position or state of motion of the first structural part. The deter mining of the condition of the at least one structural part 11 is explained in more detail in connection with the description related to the method of Figure 2.

According to an embodiment, the moving means 5 may comprise an actuator of the working machine.

According to an embodiment, the detecting means 22 may be arranged fixedly to the working machine 10. According to another embodiment, the detect- ing means may comprise detecting means releasably connectable to the working machine 10 and the data processing means 23. The arrangement 1 may comprise detecting means 22 arranged to de termine an actual position or state of motion of the first structural part 1G of the working machine 10. The detecting means may comprise at least one detector, for example.

According to an embodiment, the arrangement 1 may further comprise a user interface 3 enabling an operator to affect the working machine 10, for in stance through the control system 2 of the working machine 10. The user inter face 3 may comprise a physical user interface, in other words buttons, levels, key boards and/or other types of physical equipment enabling the operator to affect the working machine 10, a graphical user interface, such as a display, touch screen or some other type of a graphical user interface, or a combination thereof.

According to an embodiment, the detecting means may be arranged fixedly to the working machine. According to another embodiment, the detecting means comprise detecting means releasably connectable to the working machine and the data processing means.

According to an embodiment, a working machine may comprise an ar rangement described above and/or be arranged to implement at least one of the steps of a method described above.

Figure 4 illustrates schematically a first structural part 11’ and a sec- ond structural part 11" of a working machine 10 and some basic concepts of the arrangement and method described above. According to an embodiment, the first structural part 11’ and the second structural part 11" may be connected to one another by a structural part 16 connecting the first and second structural parts 11’, 11" to one another. This optional structural part 16 connecting the first and second structural parts is shown in the Figure 4 by a dashed line.

According to an embodiment, the difference between the actual posi tion of the first structural part 11’ and the computational position of the first structural part 11’ may comprise a rotational difference, such as a difference of an angle A in the Figure 4, when the actual position of the first structural part 11’ with respect to the computational position of the first structural part 11’ is shown by a first dashed line 41. According to a second embodiment, the difference be tween the actual position and the computational position of the first structural part 11’ may comprise a lateral difference, such as the difference of a distance B in the Figure 4, when the actual position of the first structural part 11’ with respect to the computational position of the first structural part 11’ is shown by a second dashed line 42. According to a third embodiment, the difference between the ac- tual position and the computational position of the first structural part 1G may comprise a combination of a rotational difference and a lateral difference.

A control limit, such as a threshold, the trend or other criteria for the condition may similarly be set for one or both of the types of the difference be- tween the actual and computational positions or state of motion, namely lateral or rotational. The difference may also take place in a direction other than an intend ed direction of movement. For instance, the difference in the position and/or state of motion of the first structural part 1G, either rotational or lateral, may take place in the direction of the intended rotation or linear movement or in a direc- tion transverse to that direction.

Figure 5 illustrates an embodiment of a working machine 10. ln the embodiment of Figure 5, the working machine 10 is a harvester ln Figure 5, some of the structural parts of the working machine 10 are marked with reference numbers. Many of these structural parts may comprise structural parts similar to the working machine 10 of Figure 1. On the other hand, the working machine 10 may also comprise structural parts different from the structural parts embodi ment of Figure 1 instead of or in addition to the structural parts described in con nection with Figure 1 and other embodiments described in this description. The working machine 10 may, for instance, comprise a tool 18, such as a harvester head ln Figure 5, the harvester head is shown holding a trunk 19.

Figure 5 also illustrates detecting means 22 provided in the working machine 10. The detecting means 22 shown in Figure 5 only illustrate one embod iment and in different embodiments, a working machine 10 may comprise none, one, two or more than two of the detecting means 22 of Figure 5 and/or one, two or multiple pieces of detecting means 22 not shown in Figure 5. ln the embodi ment of Figure 5, detecting means 22 are provided in two frame parts 11 and two boom sections of boom 14. According to another embodiments, detecting means 22 may be provided for instance in the cabin 12, a further boom section, the tool 18 and/or at least one other structural part of the working machine 10.

Figure 7 illustrates schematically an embodiment of a working ma chine 10 and a difference between an actual position and a computational posi tion of the first structural part 11’, more particularly an outer section of a boom 14, of the working machine 10. Figure 7 illustrates schematically the difference between the actual position and the computational position of the first structural part, more particularly the outer section of the boom 14, by showing the actual position of the outer section of the boom by reference 14a and a computational position of the outer section of the boom by reference 14b. Thereby, the differ ence between the actual position and the computational position of the outer sec tion of the boom 14 comprises the difference between these positions. The posi tion of the first structural part 11’ may refer to the position of the first structural part 11’ with respect to a second structural part 11". ln the embodiment of Figure 7, the second structural part 11" may comprise the inner section of the boom 14, in other words the section of the boom 14 articulated to a frame part 11, or the frame part 11, for example. The actual position of the first structural part 11’ may be detected by the detecting means 22, for example ln the embodiment of Figure 7, the trunk 19 is laid against the ground in the actual position of the boom, for example.

Data processing means 23 (not shown) may be arranged to determine the condition of at least one structural part of the working machine, such as the outer section of the boom 14, the joint articulating the outer section of the boom 14 to the inner section of the boom 14 or the frame part 11, or the joint connect ing the boom 14 to the frame part 11. The condition may be determined on the basis of the difference between the actual and computational positions or states of motion of the first structural part.

A computer program product may be in storage on a computer read- able medium and executable with a processor. The computer program product may comprise a computer readable program code, which is arranged to carry out steps of a method as set forth above or a combination thereof, as the program code is being executed with the processor. The processor may comprise the data processing means of the working machine.

lt will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The inven tion and its embodiments are not limited to the examples described above but may vary within the scope of the claims.