Control of pulse tool motors
The method and control device in pulse tools dynamically adjust motor output based on torque and angle increases to optimize speed and precision, addressing the suboptimal trade-offs in conventional tools by adapting to joint stiffness and proximity to target torque/angle, ensuring high-precision and efficient tightening.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ATLAS COPCO IND TECHNIQUE AB INTELLECTUAL PROPERTY DEPARTMENT
- Filing Date
- 2024-05-30
- Publication Date
- 2026-07-08
AI Technical Summary
Conventional pulse tools require manual adjustment of power levels based on joint characteristics, leading to suboptimal trade-offs between tightening speed and precision, and do not adapt automatically to different joint types.
A method and control device that dynamically adjust motor output based on torque and angle increases during tightening, allowing for automated optimization of speed and precision by adjusting motor power levels according to joint stiffness and proximity to target torque/angle.
Enables high-precision mounting torque with faster tightening by adapting motor output to joint characteristics, improving accuracy and speed based on joint stiffness and proximity to target, eliminating the need for manual input.
Smart Images
Figure 2026522676000001_ABST
Abstract
Description
Technical Field
[0001] The present invention generally relates to the field of controlling motors of pulse tools. Specifically, the present invention relates to the pulse strategy of such pulse tools.
Background Art
[0002] In industrial assembly, the ergonomic requirements of the operator and the accuracy of the mounting torque at the joint are very important. Therefore, so-called pulse tools are often used. A pulse tool supplies tightening torque in pulses, and the output torque between each torque pulse is zero. This is achieved by a hydraulic pulse unit that intermittently couples the motor to the output shaft or by driving the motor of the tool itself in pulses. Such pulse tools are known for achieving high-precision mounting torque and low reaction force to the operator due to the pulse technology.
[0003] Another requirement in industrial assembly is a rapid tightening operation since this can save the time (and thus cost) of the assembly procedure. This requirement may usually conflict with the requirement for high accuracy of the mounting torque. To speed up the tightening operation, it is necessary to use a high motor output. However, a high motor output may lead to a decrease in the accuracy of the mounting torque. In conventional pulse tools, the same motor output (and thus the same energy) is used for the pulses throughout the entire tightening operation.
[0004] International Publication No. 2021151674 discloses a pulse tool in which the user can set different power levels to be used at different stages of tightening. Thus, the user can adjust the power level so that it is high in the initial stages of tightening up to a specific torque threshold, and then decreases as the torque exceeds that threshold, so that tightening is performed with low power near the target torque. Therefore, when setting the pulse output up to a specific torque threshold, the user can take into account the characteristics of the joint. It is possible to adapt the power to tighten the joint as quickly as possible up to the specific torque threshold. Furthermore, since the output can be set to a low value close to the target torque, it is also possible to achieve more precise tightening.
[0005] The drawbacks of this solution are that it requires manual input and knowledge of the characteristics of the joints to which the strategy is applied. Furthermore, the preset output levels are not necessarily optimal for all joints being tightened in terms of speed and accuracy. [Prior art documents] [Patent Documents]
[0006] [Patent Document 1] International Publication No. 2021151674 [Overview of the project] [Problems that the invention aims to solve]
[0007] It would be advantageous to provide methods and control devices that eliminate or at least mitigate the aforementioned drawbacks. More specifically, it would be desirable to provide methods and control devices that enable better adjustment of the trade-off between the tightening speed and precision of different joints. [Means for solving the problem]
[0008] To better address one or more of these problems, a method and control device having the features defined in the independent claim are provided. Preferred embodiments are defined in the dependent claims.
[0009] Accordingly, according to the first embodiment, a method for controlling the motor of a pulse tool is provided. The pulse tool is configured to supply torque in pulses during a tightening operation to tighten a screw joint. This method, The steps include determining parameter values that indicate the torque and / or angle increase achieved by the pulse just executed, The steps include determining motor output control parameter values for the next pulse based on the determined parameter values that indicate an increase in torque and / or angle, The steps include controlling the motor according to the determined motor output control parameter value and generating the next pulse, The steps are repeated until the target torque and / or target angle is reached (until the tightening operation is complete), Includes.
[0010] In this embodiment, the motor is controlled to output power in the next (i.e., immediately following) pulse, depending on the torque and / or angle increase achieved in the pulse just executed (i.e., the previous) pulse. This provides a control method for adjusting the motor output (energy) during tightening depending on the characteristics of the joint. This allows for a trade-off between tightening speed and accuracy to match the joint being tightened. For example, a soft joint exhibits a smaller torque increase and a larger angle increase per pulse compared to a hard joint. Due to the relatively small torque increase step, a soft joint may typically take longer to tighten. The control method can detect this and determine a motor output control parameter value to result in an increase in motor output in the next pulse. In this way, tightening proceeds faster compared to when the motor output is not adjusted. On the other hand, if the torque increase is large (the angle increase is small) as a result of a hard joint, the control method can determine a motor output control parameter value to decrease the motor output in the next pulse, thereby reducing the torque step per pulse and consequently improving the accuracy of the final mounting torque.
[0011] In conclusion, the present invention enables an automated procedure that provides a trade-off between the speed and precision of a tightening operation that better suits different joints.
[0012] It should be understood that either or both of the torque increase and / or angle increase can be determined relative to the previous pulse. Both of these are parameters that reflect the stiffness of the joint, in opposite ways. A pulse produced with a given motor output will result in a greater torque increase and a smaller angle increase at a stiff joint compared to a soft joint.
[0013] According to one embodiment, the motor output control parameter value for the next pulse can be determined to be lower for larger torque increases and / or smaller angle increases, as indicated by the determined parameter value, and higher for smaller torque increases and / or larger angle increases, as indicated by the determined parameter value.
[0014] Small torque increases and large angle increases may indicate that the joint being tightened is relatively soft. This means there is room to increase motor output while maintaining the precision of the final tightening torque. Similarly, large torque increases and small angle increases may indicate that the joint being tightened is relatively stiff. This means that reducing motor output can improve the precision of the final tightening torque, even at the cost of a slightly slower tightening speed compared to not adjusting the motor output.
[0015] This embodiment can be implemented in various ways. For example, one or more thresholds can be set in advance for torque and / or angle increase. If the torque increase of the pulse just executed is greater than a predetermined first threshold, the motor output control parameter value can be determined such that the value of the next pulse is smaller than the value of the pulse just executed (for example, by a predetermined amount). Furthermore, if the torque increase of the pulse just executed is less than a preset second threshold (smaller than the first threshold), the motor output control parameter value can be determined such that the value of the next pulse is higher than the value of the pulse just executed (for example, by a predetermined amount). Similar thresholds can be set for angle increase, but the logic is reversed.
[0016] According to another embodiment, the torque / angle increase value in the previous pulse can be correlated with a specific motor output control parameter value for the next pulse in a lookup table or a predetermined function.
[0017] According to one embodiment, the method may further include the step of receiving an input (e.g., from a user interface) that indicates a desired trade-off between the speed and precision of the tightening operation before the tightening operation begins, and determining the motor output control parameter value for the next pulse may further be based on the received input indicating the desired trade-off between speed and precision.
[0018] For example, if the input requires a higher speed at the expense of lower precision, the motor output control parameter value for the next pulse can be determined to be higher than if the input required higher precision at the expense of lower speed.
[0019] For example, the user can select from two or more operating modes for the pulse tool, such as one precision mode, one normal mode, and one rapid mode.
[0020] This embodiment has the advantage of allowing users to adjust the trade-off between speed and accuracy to suit their specific application.
[0021] According to one embodiment, the step of determining parameter values indicating torque and / or angle increase may include determining the difference between a received input indicating torque and / or angle achieved in the pulse just performed and a received input indicating torque and / or angle achieved in the pulse immediately preceding the pulse just performed.
[0022] For example, parameter values indicating torque and / or angle increase may be based on inputs received from a torque transducer and / or an angle encoder and / or some other means for measuring or estimating torque and / or angle in the executed pulse.
[0023] According to one embodiment, the method can further include receiving an input indicating the (total) torque and / or total angle achieved with the just-executed pulse (i.e., the total torque and / or total angle achieved by the previous tightening), and the step of determining the motor output control parameter values for the next pulse can be based on the received input indicating the (total) torque and / or total angle achieved with the just-executed pulse. Thus, the motor output control parameter values for the next pulse can also be based on at what point in the tightening operation the next pulse is, i.e., how close the next pulse is to the target torque / target angle. In other words, determining the motor power control parameter values for the next pulse can further be based on how close the total torque (of the just-executed pulse) indicated by the received input is to the target torque, and / or how close the total angle (of the just-executed pulse) indicated by the received input is to the target angle. For example, the method can include comparing the total torque and / or total angle (indicated by the received input) with the target torque and / or target angle, respectively. At the beginning of the tightening operation, high pulse energy (motor output) is useful as it enables a rapid initial part of the tightening, while low pulse energy (motor output) is better towards the end of the tightening operation as it improves the accuracy of the finally introduced torque. Thus, the motor power control parameter values for the next pulse can be determined such that the closer the total torque and / or total angle are to the target torque and / or target angle, the lower the motor power is determined (during at least the major part of the torque build-up phase of the tightening, e.g., excluding the very first few pulses of that phase).
[0024] This embodiment can be realized, for example, by adapting the target torque increase and / or the target angle increase of each pulse (which can be expressed, for example, with respect to one or more thresholds for torque and / or angle increases that can be preset as described above) based on the proximity to the target torque / target angle of tightening. In this way, the proximity to the final target torque and / or angle of tightening can be used to determine / indicate one or more thresholds (or targets) for comparison with the torque / angle increase just achieved. Therefore, both the proximity to the final target torque / angle of tightening and the characteristics of the joint are optimized, enabling high-precision mounting torque to be achieved while tightening more quickly.
[0025] For example, the target torque increase and / or the target angle increase can be made smaller as the pulse just executed is closer to the end of tightening, thereby generally making the torque step at the start of tightening larger (time can be saved), and generally making the torque step at the end of tightening smaller (can promote high-precision tightening torque). The target torque increase and / or the target angle increase can be decreased continuously or stepwise, for example, as tightening progresses.
[0026] In this specification, the term “motor output control parameter” means a parameter that, when adjusted, causes the output power (energy) of the motor to be adjusted accordingly. It may be set as a control object of a motor control device, or converted into a control object of a motor control device. Motor output control parameters are, for example, motor output, motor current, energy output from the motor, motor torque, and motor speed (peak value of motor speed in the next pulse cycle). For example, if the motor output control parameter value is determined in terms of motor output, the determined motor output value can be used as an input to a motor control device, or it can be converted to, for example, a motor current value, which can then be used as an input to a motor control device. In this context, a motor control device means a device that controls a motor to achieve a control objective based on a received control objective (for example, part of a control device for a pulse tool).
[0027] According to one embodiment, pulses can be supplied by a hydraulic pulse unit of a pulse tool, which intermittently couples a motor to the output shaft of the pulse tool via a hydraulic coupling mechanism.
[0028] In this type of pulse tool, the motor is driven to output torque / power / energy continuously (as opposed to intermittently) during tightening, and it is the hydraulic pulse unit that generates the pulses. The motor's continuous torque / power / energy can be adjusted according to motor output control parameter values that are repeatedly determined during tightening.
[0029] Alternatively, the motor itself can be driven in a pulsed (intermittent) manner to supply pulses to the output shaft of the pulse tool, in which case the motor's output power / torque / energy is zero between pulses. Therefore, the motor does not supply torque / power / energy between pulses. The intermittent torque / power / energy of the motor can be adjusted according to motor output control parameter values that are repeatedly determined during tightening.
[0030] According to a second aspect, a control device is provided for controlling the motor of a pulse tool. The pulse tool is configured to supply torque in pulses during a tightening operation that tightens a screw joint. The control device is configured to perform the method according to the first aspect.
[0031] According to one embodiment, a system is provided comprising a pulse tool configured to provide pulsed torque during a tightening operation for tightening a screw joint, the pulse tool comprising a motor and a control device according to a second embodiment for controlling the motor of the pulse tool.
[0032] According to one embodiment, when the program is executed by a computer (such as a control device), a computer program is provided that includes instructions causing the computer to perform the method according to the first embodiment.
[0033] According to one embodiment, a computer-readable storage medium is provided which, when executed by a computer (such as a control device), includes instructions that cause the computer to perform the method according to the first embodiment.
[0034] It should be noted that the embodiments of the present invention relate to all possible combinations of the features described in the claims. Furthermore, it should be understood that all of the various embodiments described in the Method are combinatorial with the control devices defined according to a second aspect of the present invention.
[0035] The above and other embodiments will be described in more detail in the following exemplary and non-limiting detailed description of embodiments with reference to the attached drawings. [Brief explanation of the drawing]
[0036] [Figure 1] This shows a pulse tool equipped with a hydraulic pulse unit according to one embodiment. [Figure 2] This shows a pulse tool equipped with an intermittently driven electric motor according to one embodiment. [Figure 3] This graph shows how different parameters change during tightening according to one embodiment. [Figure 4] A method according to one embodiment is shown. [Figure 5] This graph shows how the motor output changes during five tightening cycles of five different joints according to one embodiment. [Modes for carrying out the invention]
[0037] All figures are schematic diagrams and not necessarily to scale. In general, they show only the parts necessary to illustrate the embodiments, and other parts may be omitted. Throughout the specification, similar reference figures refer to similar elements.
[0038] A pulse tool 1 according to one embodiment will be described with reference to Figure 1. The pulse tool 1 can be configured to tighten threaded fasteners during industrial assembly. The pulse tool 1 comprises a motor 12, which may preferably be an electric motor 12. The motor 12 may comprise a rotor 14 and a stator 13. The tool 1 may further comprise an output shaft 16. The output shaft 16 may be located at the front end 10a of the housing 10 of the tool 1. The tool 1 may further comprise a hydraulic pulse unit 15 configured to intermittently couple the motor 12 to the output shaft 16 via a hydraulic coupling mechanism. For example, the pulse unit 15 may comprise an inertia drive member 18 coupled to the rotor 14 in a rotatable fixed manner. Thus, the inertia drive member 18 rotates together with the motor 12. The inertia drive member 18 may comprise a cylindrical fluid chamber 19 into which the impulse receiving portion 11 of the output shaft 16 extends. The configuration, including the cam profile and piston, is arranged to intermittently transmit rotational energy from the inertia drive member 18 to the impulse receiving portion 11. Such configurations are known to those skilled in the art and are not described further herein. An example of a hydraulic pulse unit is described in International Publication No. 9114541.
[0039] In this type of pulse tool 1, the motor 12 continuously supplies a relatively low torque, such as approximately 1 Nm. The hydraulic pulse unit 15 converts this continuous torque from the motor 12 into intermittent torque pulses on the output shaft 16, each of which can be, for example, approximately 15-55 Nm. Such a pulse tool 1 may hereafter be referred to as a hydraulic pulse tool.
[0040] Tool 1 may further include a control device 20. The control device 20 may include a processing circuit 201 and a memory 202. The control device 20 may be configured to control the motor 12.
[0041] Alternatively, the control device 20 can be located outside the tool 1 in a manner that allows it to communicate.
[0042] The tool 1 may further include a sensor 3 arranged to sense parameters indicating torque and / or angle achieved by torque pulses supplied by the output shaft 16. For example, the sensor may include an angle encoder 3 arranged to measure the angular position and velocity of the output shaft 16 (or a component in a fixed rotational relationship with respect to the output shaft 16). The angle encoder 3 can sense the angular increase achieved by the pulse just performed. It can also sense the delay in the angular velocity of the output shaft 16 due to torque transmission from the tool to the fastener. This angular velocity delay indicates the torque of the performed pulse and can therefore be used to estimate / calculate the torque achieved by the performed pulse.
[0043] As an alternative or supplement, the sensor may include a strain gauge (not shown) positioned to sense the strain on the output shaft 16 (or a component in a fixed rotational relationship with respect to the output shaft 16), which indicates the torque of the pulse being performed. For example, the sensor may include a torque transducer.
[0044] Figure 2 shows another exemplary embodiment of the pulse tool 101 of the present disclosure. In this embodiment, pulses are produced by driving an electric motor 112 in a pulsed (intermittent) manner. Pulses can be produced when the electric motor 112 accelerates in play in the gear arrangement 111 between the electric motor 112 and the output shaft 116. As a result, energy from the electric motor 112 is transferred to the output shaft 116, producing pulses on the output shaft 116. The electric motor 112 may comprise a rotor and a stator. Such a pulse tool 101 may hereafter be referred to as a direct-drive pulse tool.
[0045] For example, the gear arrangement 111 may include a play unit (not shown). Alternatively, the play unit may be arranged separately from the gear arrangement 111. The purpose of the play unit is to add play to the play present in the gear arrangement 11. The advantage of a separate play unit is that the amount of play can be selected. If a large amount of play is selected for the play unit, there is more time to control the speed of the electric motor 112 before the play in the play unit closes and the electric motor 112 couples with the output shaft 116 and imparts torque pulses to the output shaft 116.
[0046] Tool 101 may further include components similar to those of tool 1 described with reference to Figure 1 (such as a sensor 3 and a control device 20).
[0047] Next, the principles of embodiments of the present invention will be described with reference to Figures 3 and 4. Figure 3 shows how the determined motor output control parameter value M(a), the actual motor (and inertia drive member) speed (b), the pulse torque (c), and the joint mounting torque (d) change throughout the torque build-up phase (following the run-down phase) of a tightening operation performed by a pulse tool, such as one of the pulse tools described above. Figure 4 shows a method according to an embodiment.
[0048] Optionally, the control device 20 can be configured to receive an input (e.g., via a user interface) indicating a desired trade-off between the speed and accuracy of the tightening operation before the tightening operation begins (401). For example, the user can select one of the following modes: accurate mode, normal mode, or rapid mode.
[0049] First, the rundown of the tightening operation is completed. The start motor output control parameter value, which the control device 20 can use to control the motor accordingly, can be preset for the first one or several pulses of the torque build-up phase. Optionally, this start motor output control parameter value can be the same as the rundown motor output control parameter value.
[0050] Furthermore, the control device 20 is configured to determine parameter values that indicate the torque and / or angle increase achieved by the immediately preceding pulse n (402). This can be done, for example, by calculating the difference d between the torque achieved by the pulse n just now and the torque achieved by the immediately preceding pulse n-1 (see graph c in Figure 3). The angle increase can be derived, for example, directly from the angle encoder.
[0051] The control device 20 may be further configured to receive an input indicating the total torque and / or total angle achieved in the pulse just performed (i.e., the total torque and / or total angle achieved by the tightening so far). The control device 20 may be configured to compare this received input with the (final) target torque / angle of the tightening.
[0052] The control device 20 is further configured to determine a motor output control parameter value M for the next pulse n+1 (graph a in Figure 3) based on determined parameter values indicating torque and / or angle increases (403). This can be done, for example, by comparing the torque increase and / or angle increase, as indicated by the parameters, with target torque increase and / or target angle increase, respectively (e.g., indicated by thresholds of 1 or 2 or more). For example, if the torque increase, as indicated by the received input parameters, is lower than the target torque increase for that pulse n, a higher motor output control parameter value M can be determined, and vice versa. This can be the case, for example, when the joint is relatively soft.
[0053] The control device 20 can be configured to control the motor according to a further determined motor output control parameter value M, thereby producing the next pulse n+1 (404). Thus, the motor output control parameter value M can constitute the control target when controlling the motor. The motor output control parameter value M can indicate the target energy of the next pulse n+1. The motor output control parameter can be expressed, for example, in terms of the motor output / energy / torque that the motor should output in the next pulse period, the motor current that should be input to the motor in the next pulse period, or the motor speed that the motor should output in the next pulse period, particularly the peak motor speed (see the peak in graph b of Figure 3). The motor's rotational speed will build up to the peak speed after the pulse is executed (in both hydraulically driven pulse tools and directly driven pulse tools). Then, when torque is transmitted to the joint (via the hydraulic coupling in the case of hydraulic pulse tools), the motor speed rapidly decreases to (at least substantially) zero. The value of the peak speed will determine the energy of the pulse.
[0054] The motor output control parameter value M for the next pulse n+1 can be determined to be lower for larger torque increases and / or smaller angle increases, and higher for smaller torque increases and / or larger angle increases. Thus, the algorithm executed by the control device 20 can adapt the motor output to the stiffness of the joint. As shown in Figure 3, the determined motor output control parameter value M may, for example, be increased in the first few steps and then decreased in the next steps until the end of the tightening operation. Making the steps smaller towards the end improves tightening accuracy, while making the steps larger at the beginning speeds up the tightening.
[0055] Optionally, the motor output control parameter value M for the next pulse n+1 can also be determined based on the received input, which represents the desired trade-off between speed and accuracy. When faster tightening is desired, the control device 20 can generally determine a higher motor output control parameter value compared to when more precise tightening is desired.
[0056] Optionally, the motor output control parameter value M for the next pulse n+1 can be further determined based on the received input indicating the (total) torque and / or total angle achieved in the pulse just performed. The closer the received torque / total angle of the previous pulse is to the target torque or target angle, the lower the motor output control parameter value M can be determined for the next pulse n+1. Thus, the algorithm operated by the control device 20 can also adapt the motor output to how far the tightening has progressed (i.e., how close the pulse just performed is to the final target). This can be achieved, for example, by setting the above-mentioned target torque increase and / or target angle increase for each pulse so that it decreases towards the end of the tightening operation (i.e., as the total torque and / or total angle of the pulse just performed approaches the final target). This can be a linear decrease or a decrease according to a predetermined function.
[0057] Step 402, which determines parameter values indicating torque and / or angle increase; Step 403, which determines motor output control parameter values; and Step 404, which controls the motor accordingly, are then repeated until the target torque and / or target angle is reached, thereby ending the tightening operation.
[0058] Figure 5 shows how the control device 20 adjusts the motor output (y-axis) as five exemplary tightening operations P1-P5 for five different joints progress (the mounting torque of the joint is shown on the x-axis). Each circle / rhombus / square / triangle represents one pulse. All five tightening operations P1-P5 can begin with a preset motor output control parameter value, which in this embodiment corresponds to approximately 83% of the motor's maximum output.
[0059] During the tightening operation P1, the control device 20 quickly detects that the torque increase is relatively low (e.g., below a predetermined threshold) and therefore decides to increase the motor output control parameter value. As shown in the figure, the motor output control parameter value quickly reaches the maximum level, thereby the motor output is 100% of the motor's maximum output, which continues until the target torque of 40 Nm is reached, and the tightening is completed. This can typically occur when tightening very soft joints. The generally high motor output during tightening ensures that the tightening proceeds faster than if the motor output remained at 83% of the initial value until the end of tightening.
[0060] On the other hand, during the tightening operation P5, the control device 20 immediately detects that the torque increase is relatively high (e.g., above a predetermined threshold) and therefore decides to reduce the motor output control parameter value. As shown in the figure, the motor output control parameter value will gradually decrease until the target torque of 40 Nm is reached and tightening is completed (consequently, the motor output will also decrease). This can typically occur when tightening very tight joints. The generally low motor output during tightening ensures that a more precise final mounting torque is provided compared to a case where tightening proceeds slowly and the motor output remains at 83% of the initial value until tightening is completed.
[0061] The control device 20 can operate similarly during the tightening operations P2-P4.
[0062] Those skilled in the art will understand that the present invention is not limited to the embodiments described above. Rather, many modifications and variations are possible within the scope of the appended claims.
[0063] In addition, by examining the drawings, disclosures, and appended claims, a person skilled in the art can understand variations of the disclosed embodiments and carry out the inventions described in the claims. In the claims, the term “comprising” does not preclude other elements or steps, and the indefinite article “a” or “an” does not preclude the plural. The mere fact that certain means are described in different dependent claims does not indicate that a combination of these means cannot be advantageously utilized.
[0064] 1. Pulse tool 12 motors 101 Pulse Tools 112 Motor 20 Control device 201 Processing Circuit 202 memory
Claims
1. A method (400) for controlling the motors (12, 112) of a pulse tool (1, 101), wherein the pulse tool is configured to provide torque in pulses during a tightening operation for tightening a screw joint, and the method is Step (402) of determining a parameter value (d) that indicates the torque increase and / or angle increase achieved by the pulse (n) that has just been executed, Step (403) of determining a motor output control parameter value (M) for the next pulse (n+1) based on the determined parameter value indicating the torque increase and / or the angle increase, Step (404) of controlling the motor according to the determined motor output control parameter value to generate the next pulse, The steps are repeated until the target torque and / or target angle is reached, A method that includes this.
2. The method according to claim 1, wherein the motor output control parameter value of the next pulse is determined to be lower for larger torque increases and / or smaller angle increases, as indicated by the determined parameter value, and higher for smaller torque increases and / or larger angle increases, as indicated by the determined parameter value.
3. The method according to claim 1, further comprising the step (401) of receiving an input indicating a desired trade-off between the speed and precision of the tightening operation before the tightening operation begins, and the step of determining a motor output control parameter value for the next pulse further based on the received input indicating the desired trade-off between speed and precision.
4. The method according to claim 1 or 2, wherein the step of determining the parameter value indicating the torque increase and / or angle increase includes determining the difference (d) between a received input indicating the torque and / or angle achieved in the pulse just performed and a received input indicating the torque and / or angle achieved in the pulse (n-1) immediately preceding the pulse just performed.
5. A step of receiving an input indicating the total torque and / or total angle achieved in the tightening operation so far by the pulse (n) that has just been executed, It further includes, The method according to any one of claims 1 to 4, wherein the step of determining the motor output control parameter value for the next pulse (n+1) is further based on how close the total torque and / or total angle indicated by the received input is to the target torque and / or target angle, respectively.
6. The method according to any one of claims 1 to 5, wherein the motor output control parameter is one of motor output, motor current, motor torque, energy output from the motor, and motor speed.
7. The method according to any one of claims 1 to 6, wherein the pulse is supplied by a hydraulic pulse unit (15) of the pulse tool (1), and the hydraulic pulse unit intermittently couples the motor (12) to the output shaft (16) of the pulse tool via a hydraulic coupling mechanism.
8. The method according to any one of claims 1 to 6, wherein the motor (112) is driven in a pulse manner to supply the pulses to the output shaft (116) of the pulse tool (101), and the output of the motor is zero between the pulses.
9. A control device (20) for controlling the motor of a pulse tool, wherein the pulse tool is configured to provide pulsed torque during a tightening operation for tightening a screw joint, and the control device (20) is configured to perform the method according to any one of claims 1 to 8.
10. A pulse tool equipped with a motor is configured to provide pulsed torque during a tightening operation to tighten a screw joint, A control device according to claim 9 for controlling the motor of the pulse tool, A system equipped with these features.
11. A computer program that, when executed by a computer, includes instructions causing the computer to perform the method according to any one of claims 1 to 8.
12. A computer-readable storage medium that, when executed by a computer, includes an instruction causing the computer to perform the method according to any one of claims 1 to 8.