Motor for controlling a pulse tool

Abstract

A method of controlling a motor of a pulse tool is provided. The pulse tool is arranged to provide torque in the form of pulses during a tightening operation to tighten the threaded joint. The method comprises: determining a parameter value (d) indicative of a torque and / or angle increase achieved by the just executed pulse (n); determining a motor power control parameter value (M) for a next pulse (n + 1) based on said determined parameter value indicative of an increase in torque and / or angle; controlling the motor according to the determined motor power control parameter value to generate a next pulse; and repeating these steps until the target torque and / or angle is reached. Thus, a control method is provided that will adjust the power (energy) of the motor during tightening according to the characteristics of the joint. This enables a tradeoff between the speed and accuracy of tightening tailored to the tightened joint.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to the field of controlling a motor of a pulsing tool. In particular, the present invention relates to a pulsing strategy for such a pulsing tool. BACKGROUND

[0002] In industrial assembly, the requirements for operator ergonomics and the accuracy of the installation torque of a joint are of great importance. Therefore, so-called pulsing tools are often used. Pulsing tools deliver the tightening torque in pulses, wherein the output torque is zero between each torque pulse. This can be achieved by means of a hydraulic pulse unit that intermittently engages the motor to the output shaft, or by a motor of the tool itself that is driven in pulses. Such pulsing tools are known for achieving a high accuracy of the installation torque due to the pulsing technology and a low reaction force on the operator.

[0003] Another desire in industrial assembly is a fast tightening operation, as this can save time (and thus costs) in the assembly process. This desire can often conflict with the requirement for a high accuracy of the installation torque. In order to speed up the tightening operation, a higher motor power must be used. However, a higher motor power can lead to a reduced accuracy of the installation torque. In conventional pulsing tools, the same motor power (and thus the same energy) is used for the pulses throughout the tightening operation.

[0004] WO2021151674A1 discloses a pulsing tool that enables the user to set different power levels to be used at different stages of the tightening. Thus, the user can turn the power level up at the beginning of the tightening until a certain torque threshold is reached, and then turn the power level down when the torque exceeds this torque threshold, so that the tightening is performed at a lower power close to the target torque. Thus, the user is able to take the characteristics of the joint into account when setting the power of the pulses up to a certain torque threshold. The power can be adjusted so that the joint is tightened to the certain torque threshold as quickly as possible. Since the power can be set to a lower value close to the target torque, a more accurate tightening can also be achieved.

[0005] A disadvantage of this solution is that it requires manual input and knowledge of the characteristics of the joint to which the strategy is to be applied. Furthermore, the preset power levels can not be the best choice for all joints to be tightened in terms of speed and accuracy. SUMMARY

[0006] It would be advantageous to implement a method and control device that overcome or at least alleviate the above-mentioned disadvantages. In particular, it would be desirable to provide a method and control device that enable a better trade-off between the tightening speed and the accuracy of different joints.

[0007] To better address one or more of these issues, a method and control device are provided having features defined in the independent claims. Preferred embodiments are defined in the dependent claims.

[0008] Thus, according to a first aspect, a method of controlling a motor of a pulsing tool is provided. The pulsing tool is arranged to provide torque in the form of pulses during a tightening operation to tighten a threaded joint. The method comprises: - determining a parameter value indicative of a torque increase and / or an angle increase achieved by the just performed pulse; - determining a motor power control parameter value for the next pulse based on said determined parameter value indicative of the torque increase and / or the angle increase; - controlling the motor in accordance with the determined motor power control parameter value to produce the next pulse; and repeating these steps until a target torque and / or a target angle is reached (and the tightening operation is ended).

[0009] In this aspect, the motor output is controlled in terms of power in the next (i.e. immediately following) pulse in dependence on the torque and / or angle increase achieved in the just performed (i.e. immediately preceding) pulse. Thus, a control method is provided which will adjust the power (energy) of the motor during the tightening process in dependence on the characteristics of the joint. This enables a customised trade-off between speed and accuracy of the tightening for the tightened joint. For example, a soft joint will imply a lower torque increase and a higher angle increase per pulse compared to a hard joint. Due to the relatively small torque increase step, a softer joint can typically require a longer time to tighten. The control method can detect this and determine a motor power control parameter value to provide an increase in motor power in the next pulse. In this way, the tightening will proceed faster than if no adjustment of the motor power is made. On the other hand, if the torque increase is higher (and the angle increase lower) due to the joint being harder, the control method can determine a motor power control parameter value to decrease the motor power in the next pulse so that the torque step per pulse will be smaller, which in turn will result in a better accuracy of the final installed torque.

[0010] In summary, the invention enables an automated procedure which provides a better trade-off between speed and accuracy of the tightening operation for different joints.

[0011] It will be appreciated that either or both of the torque increase and the angle increase can be determined for the previous pulse. These two parameters reflect the stiffness of the joint in opposite ways. A pulse with a given motor power will result in a larger torque increase and a smaller angle increase for a hard joint compared to a soft joint.

[0012] According to embodiments, the motor power control parameter value for the next pulse can be determined as being lower when the torque increase and / or the angle increase is larger as indicated by the determined parameter value, and as being higher when the torque increase and / or the angle increase is smaller as indicated by the determined parameter value.

[0013] A smaller torque increase and a larger angle increase can indicate that the joint being tightened is relatively soft. This means that there is room to increase the motor power output while still achieving good accuracy of the final installed torque. Similarly, a larger torque increase and a smaller angle increase can indicate that the joint being tightened is relatively hard. This means that it is better to decrease the motor power output in order to be able to achieve good accuracy of the final installed torque, even if this comes at the cost of a slightly slower tightening speed compared to if no adjustment of the motor power output is made.

[0014] The embodiments can be implemented in different ways. For example, one or more threshold values for the torque and / or angle increase can be pre-set, such that if the torque increase in the just performed pulse is larger than a first predetermined threshold value, the motor power control parameter value for the next pulse is determined to be lower (e.g. by a predetermined amount) than the motor power control parameter value for the just performed pulse. Furthermore, if the torque increase in the just performed pulse is smaller than a second predetermined threshold value (lower than the first predetermined threshold value), the motor power control parameter value for the next pulse is determined to be higher (e.g. by a predetermined amount) than the motor power control parameter value for the just performed pulse. Similar threshold values can be set for the angle increase, but with the logic reversed.

[0015] According to another example, the value of the torque / angle increase in the preceding pulse can be associated with a certain motor power control parameter value for the next pulse in a look-up table or with a predetermined function.

[0016] According to embodiments, the method can further comprise receiving (e.g. from a user interface) an input indicating a desired trade-off between speed and accuracy of the tightening operation before the tightening operation is started, wherein determining the motor power control parameter value for the next pulse is further based on the received input indicating the desired trade-off between speed and accuracy.

[0017] For example, if the input indicates a desire for higher speed at the cost of lower accuracy, the motor power control parameter value for the next pulse can be determined to be higher compared to if the input indicates a desire for higher accuracy at the cost of lower speed.

[0018] For example, the user can be able to select between two or more modes of operation of the pulsing tool, e.g. an accurate mode, a standard mode and a fast mode.

[0019] An advantage of the present embodiment is that it enables the user to tailor the trade-off between speed and accuracy to the specific application.

[0020] According to embodiments, determining the parameter value indicative of the increase in torque and / or angle can comprise determining a difference between a received input indicative of the torque and / or angle achieved in the just performed pulse and a received input indicative of the torque and / or angle achieved in the pulse immediately preceding the just performed pulse.

[0021] For example, the parameter value indicative of the increase in torque and / or angle can be based on input received from a torque sensor and / or from an angle encoder and / or any other means for measuring or estimating the torque and / or angle in the performed pulse.

[0022] According to embodiments, the method can further comprise receiving an input indicative of the (total) torque and / or total angle achieved in the just performed pulse (i.e. the total torque and / or angle achieved so far by the tightening), wherein determining the motor power control parameter value for the next pulse can be further based on the received input indicative of the (total) torque and / or total angle achieved in the just performed pulse. In this way, the motor power control parameter value for the next pulse can also be based on the time of the next pulse in the tightening operation, i.e. how close the next pulse is to the target torque / angle. In other words, determining the motor power control parameter value for the next pulse can be further based on how close the total torque (of the just performed pulse) is to the target torque and / or how close the total angle (of the just performed pulse) is to the target angle as indicated by the received input. For example, the method can comprise the step of comparing the total torque and / or total angle (as indicated by the received input) to the target torque and / or target angle, respectively. At the beginning of the tightening operation, high pulse energy (motor power) is beneficial as it provides a fast first part of the tightening, whereas low pulse energy (motor power) is better close to the end of the tightening operation as it will improve the accuracy of the final installed torque. Thus, the motor power control parameter value for the next pulse can be determined such that the closer the total torque and / or total angle is to the target torque and / or target angle, the lower the determined motor power (at least during the main part of the torque build-up phase of the tightening, e.g. except for the first few pulses of this phase).

[0023] This embodiment can be implemented, for example, by adjusting the target torque increase and / or target angle increase of each pulse based on the proximity to the target torque / angle of tightening. In this way, the proximity to the final target torque and / or angle of tightening can determine / specify one or more thresholds (or targets) for comparison with the torque / angle increase just implemented. Thus, both the proximity to the final target torque / angle of tightening and the characteristics of the joint are optimized, resulting in even faster tightening while the installation torque has high accuracy.

[0024] For example, the closer the just performed pulse is to the end of the tightening, the lower the target torque increase and / or target angle increase can be, thereby enabling a substantially larger torque step at the beginning of the tightening (which saves time) and a substantially lower torque step at the end of the tightening (which promotes high accuracy of the installation torque). The target torque increase and / or target angle increase can be lowered continuously, for example, as the tightening progresses, or stepwise.

[0025] In this specification, the term "motor power control parameter" means a parameter that, when adjusted, will cause the output power (energy) of the motor to be adjusted accordingly. It can itself be set as a control target of the motor controller, or it can be converted into a control target of the motor controller. The motor power control parameter can be, for example, any one of the following parameters: motor power, motor current, energy output from the motor, motor torque, and motor speed (i.e., peak motor speed in the next pulse period). For example, if the motor power control parameter value is determined from the perspective of motor power, the determined motor power value can itself be used as an input to the motor controller, or it can be converted into, for example, a motor current value, which in turn can be used as an input to the motor controller. In this context, the motor controller means a device that adjusts the motor based on the received control target to achieve that control target (e.g., as part of the control device of the pulsing tool).

[0026] According to an embodiment, the pulses can be provided by a hydraulic pulsing unit of the pulsing tool, wherein the hydraulic pulsing unit intermittently engages the motor to the output shaft of the pulsing tool via a hydraulic engagement mechanism.

[0027] In such a pulsing tool, during tightening, the drive motor outputs continuous torque / power / energy (as opposed to intermittent), and it is the hydraulic pulsing unit that generates the pulses. During tightening, the continuous torque / power / energy of the motor can be adjusted according to the repeatedly determined motor power control parameter value.

[0028] Alternatively, the motor itself can be driven in a pulsed (intermittent) manner to provide pulses on the output shaft of the pulsed tool, where the output power / torque / energy of the motor is zero between the pulses. Thus, the motor does not transfer torque / power / energy between the pulses. During tightening, the intermittent torque / power / energy of the motor can be adjusted according to the repeatedly determined motor power control parameter values.

[0029] According to a second aspect, there is provided a control device for controlling a motor of a pulsed tool. The pulsed tool is arranged to provide torque in pulses during a tightening operation to tighten a threaded joint. The control device is configured to perform the method according to the first aspect.

[0030] According to an embodiment, there is provided a system comprising a pulsed tool and a control device for controlling a motor of a pulsed tool according to the second aspect, the pulsed tool being arranged to provide torque in pulses during a tightening operation to tighten a threaded joint, the pulsed tool comprising the motor.

[0031] According to an embodiment, there is provided a computer program comprising instructions which, when the program is executed by a computer (e.g. the control device), cause the computer to carry out the method according to the first aspect.

[0032] According to an embodiment, there is provided a computer-readable storage medium comprising instructions which, when executed by a computer (e.g. the control device), cause the computer to carry out the method according to the first aspect.

[0033] It should be noted that embodiments of the present application relate to all possible combinations of the features recited in the claims. Furthermore, it should be understood that the various embodiments described for the method can all be combined with the control device defined according to the second aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0034] These and other aspects will now be described in greater detail in the following illustrative and non-limiting detailed description of embodiments thereof.

[0035] Figure 1 A pulsed tool comprising a hydraulic pulse unit according to an embodiment is shown.

[0036] Figure 2 A pulsed tool with an intermittently driven electric motor according to an embodiment is shown.

[0037] Figure 3 A graph showing how different parameters vary during a tightening process according to an embodiment is shown.

[0038] Figure 4 A method according to an embodiment is shown.

[0039] Figure 5 A graph is shown illustrating how the motor power output varies during five tightening processes of five different joints according to an embodiment.

[0040] All drawings are schematic, not necessarily to scale, and generally only show the components that are necessary in order to illustrate the embodiments, wherein other components can be omitted. Throughout the description, like drawing references mean like elements. DETAILED DESCRIPTION

[0041] Reference will be made to Figure 1 A pulse tool 1 according to an embodiment is described. The pulse tool 1 can be arranged to tighten threaded fasteners in an industrial assembly process. The pulse tool 1 comprises a motor 12, which can preferably be an electric motor 12. The motor 12 can comprise a rotor 14 and a stator 13. The tool 1 can further comprise an output shaft 16. The output shaft 16 can be arranged at a front end 10a of a housing 10 of the tool 1. The tool 1 can further comprise a hydraulic pulse unit 15 arranged to intermittently couple the motor 12 to the output shaft 16 via a hydraulic coupling mechanism. For example, the pulse unit 15 can comprise an inertia drive member 18 rotatably fixedly coupled to the rotor 14. The inertia drive member 18 will thus rotate with the motor 12. The inertia drive member 18 can comprise a cylindrical fluid chamber 19 into which a pulse receiving portion 11 of the output shaft 16 extends. An arrangement comprising a cam profile and a piston is arranged to intermittently transfer rotational energy from the inertia drive member 18 to the pulse receiving portion 11. Such an arrangement is known to the skilled person and will not be described further herein. An example of a hydraulic pulse unit is described in WO9114541A1.

[0042] In this type of pulse tool 1, the motor 12 will deliver a continuous, relatively low torque, for example a torque of about 1 Nm. The hydraulic pulse unit 15 will then convert this continuous torque from the motor 12 into intermittent torque pulses on the output shaft 16, wherein each torque pulse can for example be about 15 Nm to 55 Nm. This type of pulse tool 1 can be referred to as a hydraulic pulse tool hereinafter.

[0043] The tool 1 can further comprise a control device 20. The control device 20 can comprise a processing circuit 201 and a memory 202. The control device 20 can be configured to control the motor 12.

[0044] Alternatively, the control device 20 can be arranged outside of the tool 1 and in communication therewith.

[0045] The tool 1 can further comprise a sensor 3 arranged to sense a parameter indicative of the torque and / or angle achieved by the torque pulse delivered by the output shaft 16. For example, the sensor can comprise an angle encoder 3 arranged to measure the angular position and velocity of the output shaft 16 (or a component having a fixed rotational relationship with the output shaft 16). The angle encoder 3 can sense the angular increase achieved by the just performed pulse. It can also sense the retardation of the angular velocity of the output shaft 16 due to the torque being delivered from the tool to the fastener. This retardation of the angular velocity is indicative of the torque in the performed pulse, and can thus be used to estimate / calculate the torque achieved by the performed pulse.

[0046] Alternatively or in addition, the sensor can comprise a strain gauge (not shown) arranged to sense a strain in the output shaft 16 (or a component having a fixed rotational relationship with the output shaft 16) which is indicative of the torque in the performed pulse. For example, the sensor can comprise a torque sensor.

[0047] Figure 2 Another exemplary embodiment of the inventive pulse tool 101 is depicted. In this embodiment, the pulse is generated by driving the electric motor 112 in a pulsed (intermittent) manner. The pulse can be generated when the electric motor 112 accelerates within a gap in the gear arrangement 111 between the electric motor 112 and the output shaft 116. The energy from the motor 112 is then transferred to the output shaft 116 and a pulse is generated on the output shaft 116. The electric motor 112 can comprise a rotor and a stator. Such a pulse tool 101 can be referred to as a direct drive pulse tool hereinafter.

[0048] For example, the gear arrangement 111 can comprise a gap unit (not shown). Alternatively, the gap unit can be arranged separately from the gear arrangement 111. The purpose of the gap unit is to add a gap to the gap present in the gear arrangement 11. The advantage of a separate gap unit is that the amount of the gap can be chosen. If a larger gap is chosen in the gap unit, there will be more time to control the speed of the electric motor 112 before the gap in the gap unit closes and the electric motor 112 engages to the output shaft 116 to provide a torque pulse on the output shaft 116.

[0049] The tool 101 can further comprise components similar to the tool 1 described above (e.g. the sensor 3 and the control device 20). Figure 1 The tool 101 can further comprise components similar to the tool 1 described above (e.g. the sensor 3 and the control device 20).

[0050] The principles of the embodiments of the present application will now be described with reference to Figure 3 and Figure 4 The principles of the embodiments of the present application will now be described with reference to Figure 3It is shown how the determined motor power control parameter value M (a), the actual motor (and inertial drive member) speed (b), the pulse torque (c) and the make-up torque in the joint (d) will evolve during the entire torque build-up phase of a tightening operation performed by a pulsing tool (e.g. by any one of the above-described pulsing tools), after the rundown phase. Figure 4 It is shown a method according to an embodiment.

[0051] The control device 20 can optionally be configured to receive 401 an input (e.g. via a user interface) indicative of a desired trade-off between speed and accuracy of the tightening operation before the tightening operation is started. For example, the user can select between an accurate, a standard and a fast mode.

[0052] First, the rundown of the tightening operation is completed. For the first or few pulses of the torque build-up phase, a starting motor power control parameter value can be pre-set, according to which the control device 20 can control the motor. Optionally, this starting motor power control parameter value can be the same as the rundown motor power control parameter value.

[0053] Further, the control device 20 is configured to determine 402 a parameter value indicative of the torque and / or angular increase achieved by the just performed pulse n. For example, this can be done by calculating the difference d between the torque achieved by the just performed pulse n and the torque achieved by the pulse n-1 performed immediately before the just performed pulse n (see graph c in Figure 3 ). For example, the angular increase can be directly derived from an angular encoder.

[0054] The control device 20 can further be configured to receive an input indicative of the total torque and / or total angle achieved in the just performed pulse (i.e. the total torque and / or angle achieved so far by the tightening). The control device 20 can be configured to compare this received input to the (end) target torque / angle of the tightening.

[0055] The control device 20 is further configured to determine 403 a motor power control parameter value M for the next pulse n+1 based on the determined parameter value indicative of the torque and / or angular increase (see graph a in Figure 3 ). For example, this can be done by comparing the torque increase and / or angular increase as indicated by the parameter to a target torque increase and / or target angular increase (e.g. as indicated by one or more threshold values), respectively. For example, if the torque increase as indicated by the received parameter is lower than the target torque increase for this pulse n, a higher motor power control parameter value M can be determined, and vice versa. This can be the case, for example, if the joint is relatively soft.

[0056] The control device 20 can further be configured to control 404 the motor to produce the next pulse n+1 in dependence of the determined motor power control parameter value M. Thus, the motor power control parameter value M can constitute a control target when controlling the motor. The motor power control parameter value M can be indicative of a target energy for the next pulse n+1. For example, the motor power control parameter can be expressed from the perspective of the motor power / energy / torque output by the motor in the next pulse period, or from the perspective of the motor current input to the motor in the next pulse period, or from the perspective of the motor speed, in particular the peak motor speed output by the motor in the next pulse period (see Figure 3 the peak in the middle graph b). The speed of the motor will build up after the executed pulse (for both hydraulic and direct drive pulsed tools) until a peak speed. Then, when the torque (via the hydraulic engagement in case of a hydraulic pulsed tool) is transferred to the joint, the motor speed will quickly drop to (at least substantially) zero. The value of the peak speed will determine the energy of the pulse.

[0057] The motor power control parameter value M for the next pulse n+1 can be determined to be lower when the torque increase is larger and / or the angle increase is smaller, and higher when the torque increase is smaller and / or the angle increase is larger. Thus, the algorithm run by the control device 20 can adapt the motor power to the stiffness of the joint. As shown in Figure 3 the determined motor power control parameter value M can for example first be increased in several steps, and then decreased in the following steps, until the tightening operation is finished. The smaller steps close to the finish will improve the accuracy of the tightening, while the larger steps at the beginning will speed up the tightening.

[0058] Optionally, the motor power control parameter value M for the next pulse n+1 can also be determined based on a received input indicative of a desired trade-off between speed and accuracy. If a faster tightening is desired, the control device 20 can decide on a substantially higher motor power control parameter value than if a more accurate tightening is desired.

[0059] Optionally, the motor power control parameter value M for the next pulse n+1 can further be determined based on a received input indicative of the (total) torque and / or total angle achieved in the just executed pulse. The closer the received torque / total angle of the previous pulse is to the target torque or target angle, the lower the motor power control parameter value M for the next pulse n+1 can be determined to be. Thus, the algorithm run by the control device 20 can also adapt the motor power to the degree of tightening progress (i.e. how close the just executed pulse is to the final target). For example, this can be achieved by setting the target torque increase and / or target angle increase for each pulse as described above to decrease close to the end of the tightening operation (i.e. the closer the total torque and / or total angle of the just executed pulse is to the final target). This can be a linear decrease or according to a predetermined function.

[0060] The steps of determining 402 a parameter value indicative of an increase in torque and / or angle, determining 403 a motor power control parameter value, and controlling 404 the motor accordingly, are then repeated until the target torque and / or angle is reached, thereby ending the tightening operation.

[0061] Figure 5 It is shown how the control device 20 adjusts the motor power output (y-axis) as five exemplary tightening operations P1 to P5 of five different joints are carried out (the torque installed in the joint is represented on the x-axis). Each circle / diamond / square / triangle represents one pulse. All five tightening operations P1 to P5 can start with a preset motor power control parameter value, which in this example corresponds to approximately 83% of the maximum power output of the motor. In the tightening operation P1, the control device 20 quickly detects that the increase in torque is relatively low (e.g. below a predetermined threshold), and therefore determines to increase the motor power control parameter value. It can be seen that the motor power control parameter value quickly reaches the maximum level, whereby the motor power output is 100% of the maximum output of the motor, which will remain until the target torque of 40 Nm is reached, ending the tightening. This can typically occur when tightening very soft joints. A generally higher motor power output during the tightening will ensure that the tightening is carried out faster, compared to if the motor power output remained at the initial value of 83% until the end of the tightening.

[0062] On the other hand, in the tightening operation P5, the control device 20 quickly detects that the increase in torque is relatively high (e.g. above a predetermined threshold), and therefore determines to decrease the motor power control parameter value. It can be seen that the motor power control parameter value will gradually decrease (and therefore the motor power output also gradually decreases) until the target torque of 40 Nm is reached, ending the tightening. This can typically occur when tightening very hard joints. A generally lower motor power output during the tightening will ensure that the tightening is carried out slower, thereby providing a higher accuracy of the final installed torque, compared to if the motor power output remained at the initial value of 83% until the end of the tightening.

[0063] The control device 20 can operate similarly in the tightening operations P2 to P4.

[0064] The person skilled in the art realizes that the present application is in no way limited to the embodiments described above. On the contrary, many modifications and changes are possible within the scope of the appended claims.

[0065] Furthermore, variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that different claims depend on a common base claim does not indicate that a combination of features of the different claims cannot be used to advantage.

Claims

1. A method (400) for controlling a motor (12, 112) of a pulse tool (1, 101), the pulse tool being arranged to provide torque in the form of pulses during a tightening operation to tighten a threaded joint. The method includes: - Determine (402) the parameter value (d) indicating the torque increase and / or angle increase achieved by the pulse (n) just executed; - Based on the determined parameter values ​​indicating an increase in torque and / or an increase in angle, determine (403) the motor power control parameter value (M) for the next pulse (n+1). - Control the motor (404) according to the determined motor power control parameter value to generate the next pulse; as well as Repeat these steps until the target torque and / or target angle are achieved.

2. The method according to any one of the preceding claims, wherein, The motor power control parameter value for the next pulse is determined as follows: decrease when the torque increase is large and / or the angle increase is small as indicated by the determined parameter value, and increase when the torque increase is small and / or the angle increase is large as indicated by the determined parameter value.

3. The method according to claim 1, further comprising: Before the tightening operation begins, an input (401) is received indicating a desired trade-off between the speed and accuracy of the tightening operation, wherein the motor power control parameter value for the next pulse is determined further based on the received input indicating the desired trade-off between speed and accuracy.

4. The method according to claim 1 or 2, wherein, Determining the parameter values ​​indicating an increase in torque and / or an increase in angle includes: determining the difference (d) between the input indicating the received torque and / or angle realized in the pulse that was just executed and the input indicating the received torque and / or angle realized in the pulse (n-1) immediately preceding the pulse that was just executed.

5. The method according to any one of the preceding claims, further comprising: - Receive the input indicating the total torque and / or total angle achieved so far in the tightening operation, as indicated by the pulse (n) just executed. The determination of the motor power control parameter value for the next pulse (n+1) is further based on the degree of proximity of the total torque and / or total angle indicated by the received input to the target torque and / or target angle, respectively.

6. The method according to any one of the preceding claims, wherein, The motor power control parameters are any of the following: motor power, motor current, motor torque, energy output from the motor, and motor speed.

7. The method according to any one of the preceding claims, wherein, The pulse is provided by the hydraulic pulse unit (15) of the pulse tool (1), wherein the hydraulic pulse unit intermittently engages the motor (12) to the output shaft (16) of the pulse tool via a hydraulic engagement mechanism.

8. The method according to any one of claims 1 to 6, wherein, The motor (112) is driven in a pulsed manner to provide pulses on the output shaft (116) of the pulse tool (101), wherein the output of the motor is zero between pulses.

9. A control device (20) for controlling a motor of a pulse tool, the pulse tool being arranged to provide torque in the form of pulses during a tightening operation to tighten a threaded joint, the control device being configured to perform the method according to any one of the preceding claims.

10. A system comprising: A pulse tool, arranged to provide torque in the form of pulses during a tightening operation to tighten a threaded joint, the pulse tool including a motor; as well as The control device according to claim 9 is used to control the motor of a pulse tool.

11. A computer program comprising instructions that, when executed by a computer, cause the computer to perform the method as defined in any one of claims 1 to 8.

12. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the method as defined in any one of claims 1 to 8.

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