EP2707177B1

EP2707177B1 - Pre-settable power tool

Info

Publication number: EP2707177B1
Application number: EP12719693.9A
Authority: EP
Inventors: Lutz May
Original assignee: Abas Inc
Current assignee: Abas Inc
Priority date: 2011-05-13
Filing date: 2012-05-04
Publication date: 2019-01-09
Anticipated expiration: 2032-05-04
Also published as: EP2707177A1; WO2012156218A1

Description

Field of the Invention

The present invention relates to a device and a method for a power torque tool, and in particular to a device and a method for a pre-settable power torque tool which allows for an easier and more exact handling.

Background of the Invention

Known power torque tools for example use electricity or pressured air for driving the power torque tool. Power torque tools of the art have a torque sensing device for limiting the torque and for gaining a stop condition when operating. This however may be not very exact. In particular when using power torque tools for high efficient and high precision applications, it is important to have a well defined operation of a power torque tool.
Documents US 5 105 519 A and WO 2008/033386 A2 show examples of power torque tools of the relevant prior art.

Summary of the Invention

It would be desireable to provide an improved device and method for a power torque tool for easier and more exact handling.
The invention provides a method and device for a power torque tool, a corresponding programme element and computer readable medium according to the subject matter of the independent claims. Further embodiments are incorporated in the dependent claims.
It should be noted that the following described exemplary embodiments of the invention apply also for the method, the device, the programme element and the computer readable medium.
According to an exemplary embodiment of the invention there is provided a power torque tool comprising a drive, a shaft, a pre-setting unit, and a controlling unit, wherein the drive is mechanically coupled to the shaft, wherein the controlling unit is coupled to the drive, wherein the pre-setting unit is adapted for receiving a pre-setting value being representative for an amount of movement to be performed by the shaft, and for supplying the pre-setting value to the controlling unit, wherein the controlling unit is adapted for controlling the drive based on the pre-setting value of movement representing a movement to be performed by the shaft of the power torque tool.
Thus, a predefined setting value can be input into the power torque tool so that the power torque tool may conduct an operation in a well defined manner. The per-setting value can be used for controlling the driving process of the power torque tool. The pre-setting value may represent a movement to be conducted by the power torque tool. The power torque tool may for example automatically stop operation when the actual movement of the power torque tool has reached an amount corresponding to that of the pre-setting moving value. The pre-setting value may be a number of rotations, so that the power torque tool may automatically stop after having conducted the pre-set number of rotations. In particular when using the power torque tool for high precision applications of time-sensitive applications, the person using the power torque tool does not have to take care on the termination, as the power torque tool itself may monitor the termination condition. Such an assistance may be very helpful when using the power torque tool in racing car environments, e.g. at a pit-stop for changing wheels during a race.
According to an exemplary embodiment of the invention, the amount of movement is a rotational movement and the pre-setting value is an angular pre-setting value.
Thus, in particular when using a revolving shaft power torque tool, the precise angle can be pre-set. The angular pre-set value can be a number of full revolutions, a certain amount of a partial revolution, or a mixture thereof, e.g. a number of full revolutions an additional partial revolution. The pre-set value may for example be set in form of an angle, e.g. 800°, which corresponds to two full revolutions and an additional 80° sectional or partial rotation.
According to an exemplary embodiment of the invention, the shaft is adapted for receiving a tool.
Thus, an interface may be coupled to the shaft of the power torque tool, e.g. a nut or a bit. This interface or tool, respectively may engage into a head of a screw, so that the power torque tool can be used for different screws. A tool may be a bit, a nut, a blade or any other element being adapted for interacting with a work piece or screw or the like.
According to an exemplary embodiment of the invention, the power torque tool is a hand held power tool.
Thus, the power torque tool can be handled easily. The power torque tool can be moved to the location of e.g. a screw to be rotated by the power torque tool. The power torque tool can be a wireless device, i.e. an accumulator operated device. However, the power torque tool can also be used as a wired device, or a line connected device, e.g. for supplying power or pressured air from a reservoir.
According to an exemplary embodiment of the invention, the power torque tool comprises a position sensor being adapted for sensing a position for determining an amount of the movement of the shaft, wherein the position sensor is coupled to the controlling unit for a feed back control, wherein the amount of the movement and the pre-setting value serve as a base for controlling the drive.
Thus, the actual movement may be monitored in order to ensure that the shaft is not only driven, but has also actually conducted the intended movement. Thus, a blocking or a slipping clutch can be detected, so that the driving process only stops when the pre-set shaft movement is actually finished.
According to an exemplary embodiment of the invention, the position value is an angular position value.
Thus, the pre-setting value may directly be compared with the position value. Providing the actually detected position value and the pre-setting value as angular values corresponds to a rotational axis or shaft.
According to an exemplary embodiment of the invention, the controlling unit comprises a comparator unit for comparing the amount of the movement with the pre-setting value for determining a termination of a driving of the shaft.
Thus, the termination of the shaft movement may be determined by directly comparing the pre-setting value and the measured value. This, however, can also be coupled to other conditions or requirements which should be fulfilled before terminating the movement or rotation.
According to an exemplary embodiment of the invention, the power torque tool further comprises a predictor unit for predicting a future position of the shaft based on a rotational speed of the shaft and a reaction characteristic of the controlling unit and the shaft.
Thus, the reaction time of the system and the moving components can be considered, so that differing rotational speeds of the shaft may be considered to always arrive at the exact stopping point. In other words, predicting the future position of the shaft may be carried out by considering the reaction time of the system and the covered angle during a negative accelerating or breaking phase of the shaft. Thus, it can be avoided that the stopping process, i.e. stop the driving of the shaft, only starts after the actual movement has found to equal to the pre-set movement. In other words, it can be avoided to terminate the rotation prior or after the intended stopping position.
According to an exemplary embodiment of the invention, the reaction characteristic of the shaft is determined based on the rotational speed of the shaft and the moment of inertia of the shaft.
Thus, the varying delay in stopping the shaft owing to varying rotational speed of the shaft can be avoided. As a faster rotation generally takes a longer time o get stopped down to zero, the rotational speed can be taken as a measure for prediction the reaction time. As a shaft having a higher moment of inertia generally takes a longer time to get stopped down to zero, also the determined moment of inertia can be taken as a measure for prediction the reaction time. It should be noted that not only the moment of inertia of only the shaft can be used, but also the moment of inertia of the combination of the shaft and the interface or tool, or the combination of the shaft, the tool and the driven screw.
According to an exemplary embodiment of the invention the power torque tool further comprises a torque sensor for sensing the torque as a measure for the termination of the rotation of the shaft, and an evaluation unit for evaluating whether the shaft has performed a predetermined rotational movement before it is sensed that a torque at the shaft has extended a predetermined torque threshold.
Thus, it can be ensured that the driving process does not untimely stop, as e.g. the driven screw blocks. As a torque threshold may be used as stop criteria for the driving process, it may be of relevance to not signal a proper driving based on the detected torque, but to check whether the shaft has actually conducted a minimum number of revolutions or a minimum angular movement, so that a blocking of the screw in the gear track can be excluded when entering the gear track.
According to an exemplary embodiment of the invention the power torque tool further comprises a moment of inertia determination unit for determining a moment of inertia of the combination of the shaft and possible elements detachably coupled to the shaft.
Thus, the moment of inertia can be determined by a respective unit, e.g. by analyzing the acceleration when starting the driving process.
According to an exemplary embodiment of the invention the power torque tool further comprises a signaling unit for signaling when the amount of movement has reached the pre-setting value of movement.
Thus, the person using the power torque tool can receive information whether the intended movement has been fully completed. The information can be a "yes" or "no" information, as e.g. a green or red traffic light, but may also be a more detailed information, like e.g. an information for which reason the driving process could not be completed as intended. E.g. a flickering light in a varying frequency can inform the user on the soon termination of the driving process. The signaling process can also be coupled to a locking of the power torque tool with respect to the driven screw, so that the screw will only be released from the power torque tool if all conditions are fulfilled for a proper driving process.
According to an exemplary embodiment of the invention there is provided a method for operating a power torque tool, the method comprising receiving a pre-setting value of movement being representative for an amount of movement to be performed by a shaft of the power torque tool, sensing a position value and determining an amount of the movement of the shaft, and controlling a drive of the power torque tool based on the pre-setting value and the position value.
According to an exemplary embodiment of the invention the method further comprises predicting a future position of the shaft based on a rotational speed of the shaft and a reaction time of a controlling unit and the shaft of the power torque tool.
According to an exemplary embodiment of the invention the method further comprising sensing a torque as a measure of termination of the rotation of the shaft, and evaluating whether the shaft has performed a predetermined rotational movement before it is sensed that a torque at the shaft has extended a predetermined torque threshold.
According to an exemplary embodiment of the invention there is provided a program element, which, when being executed by a processor, is adapted to carry out the above method for operating a power torque tool.
According to an exemplary embodiment of the invention there is provided a computer readable medium having stored the above programme element.
It may be seen as a gist of the present invention to set a movement, which, however not exclusively, may be a predetermined angle or a predetermined number of rotations, after which the power torque tool is automatically stopped.
It should be noted that the above features may also be combined. The combination of the above features may also lead to synergetic effects, even if not explicitly described in detail.
These and other aspects of the present invention will become apparent from and elucidated with reference to the embodiments described hereinafter.

Brief Description of the Drawings

Exemplary embodiments of the present invention will be described in the following with reference to the following drawings.

Fig. 1.: illustrates a schematic functional overview over a power torque tool according to an exemplary embodiment of the invention.
Fig. 2.: illustrates a more detailed unction interrelationship between components of the power torque tool according to an exemplary embodiment of the invention.
Fig. 3.: illustrates a sequence of method steps according to an exemplary embodiment of the method of the invention.
Fig. 4.: illustrates a flow chart of an operating method according to an exemplary embodiment of the invention.
Fig. 5.: illustrates a more detailed flow chart of an operating method according to an exemplary embodiment of the invention.

Detailed Description of Exemplary Embodiments

Fig. 1 illustrates a power torque tool, and in particular a schematic overview over the components of a power torque tool 1. The power torque tool 1 may be of a handheld type. The power torque tool 1 according to Fig. 1 comprises a drive 10 which is coupled to shaft 20. A tool or bit or nut or the like 101 may be coupled to the shaft 20 in order to serve as an interface for a screw or the like to be rotated. A tool may be a bit, a nut, a blade or any other element being adapted for interacting with a work piece or screw or the like. The power torque tool 1 further comprises a controlling unit 40 and a pre-setting unit 30. The pre-setting unit 30 may be fed with a pre-setting value, which pre-setting value may be provided to the controlling unit 40, so that the controlling unit 40 may control the drive 10 based on the pre-setting value. The power torque tool 1 may further comprise a signaling unit 60, which signaling unit 60 may give an indication to the user on the state of the driving or the termination of the driving of the drive 10. Thus, the user can directly observe whether the driving process has terminated or for example how long the driving processes will continue before stopping. In order to monitor the driving process and the rotation of the shaft 20, the power torque tool 1 may comprise a position detector 21, and/or a torque detector 22, and/or a momentum of inertia detector 23. The position sensor or position detector 21 may provide a position value with the controlling unit 40, where the position value may be a rotational position value. Thus, the controlling unit 40 may evaluate whether the pre-setting value, which may be, for example, also a rotational value, corresponds to the already conducted rotation, so that after having conducted the rotation according to the pre-setting value, the driving process may be stopped. Further, torque sensor or torque detector 22 may provide a torque value with the controlling unit, so that the controlling unit may evaluate whether a predetermined torque has been applied or not. Further, the momentum of inertia determination unit or momentum of inertia determination sensor 23 may determine the momentum of inertia and provide the result thereof with the controlling unit 40. Thus, the controlling unit 40 may predict a further rotation after stopping the driving process, so as to arrive at the predetermined rotational movement of the shaft 20. The measurement and controlling will be further illustrated in Fig. 2.
It should be noted that the rotational position is a particular angular position of the shaft with respect to its longitudinal rotation axis. A rotational movement is a rotation around the longitudinal axis of the shaft, in particular a movement of an imaginary point of the cylindrical surface of the shaft along the circumference of the shaft. A rotational speed is the rotational movement within a particular time. Mt is a predetermined torque threshold which may be taken as a measure not to be exceeded. J is the moment of inertia, depending on the mass and mass distribution of the shaft and possibly additional components being permanently or temporary connected to the shaft. α is the amount of the movement, in particular of an imaginary point of the cylindrical surface of the shaft along the circumference of the shaft. αt is a predetermined threshold of an amount of the movement which may be taken as a minimum rotation to be conducted before terminating the rotation. αp is a pre-setting value of movement, at which the rotation should stop. αp may already consider the reaction time. x is the position value representing the position of the shaft, in particular the angular position of the shaft. xf is the future position, in particular the predicted future angular position of the shaft. Tr is the reaction time of the system.
Fig. 2 illustrates a more detailed schematic overview over the controlling unit including the input of the sensor units 21, 22, 23. The sensor units 21 (position sensor), 22 (torque sensor), and 23 (momentum of inertia sensor) may be positioned adjacent to the rotating shaft 20 in order to determine or to sense the respective values. The position sensor 22 may provide positional value x with the controlling unit 40 so that, for example the controlling unit 40 may determine a Δx in order to determine the moving distance. The moving distance at a rotating shaft is considered as an angular value α. Further, the controlling unit 40 may determine a rotational speed v by calculating the quotient Δx divided by Δt. The pre-setting unit 30 may provide the controlling unit 40 with several pre-setting values, in particular a pre-setting movement value αp. Further, threshold values can be provided by the pre-setting unit 30, for example a torque threshold Mt and a minimum movement value αt. The pre-setting unit may receive the values for example via a keypad or keyboard 31, or via a wireless data connection so as to receive the values from a remote unit. However, it should be noted that also other possible input devices can be used for the pre-setting unit 30.
The controlling unit may have, for example, a comparator unit 42 for comparing the actual movement α and the pre-setting value αp, so as to determine whether the shaft 20 has conducted a movement according to the pre-setting value αp. If so, the controlling unit may stop the driving unit in order to stop the rotational movement of the shaft 20. Thus, the user does not have to take care on the correct operation of the moving process, as the power torque tool automatically controls the moving or rotating process and stops the process when arriving at the desired condition for moving, which may, for example be a predetermined number of rotations or a predetermined angular rotation of the shaft. Further, the comparator unit 42 may compare the determined torque M and the torque threshold Mt in order to determine whether the required torque had been achieved. The result of the comparison may be provided with a CPU for further processing. The CPU for example may have a further comparator 41 for comparing the actual angular movement α with a minimum angular movement threshold αt, so that it can be determined whether a minimum rotation had been conducted before terminating the driving process. This may be relevant in cases where an untimely blocking is expected which blocking will be indentified from the result of the comparison of the torque and the torque threshold value Mt. When considering a minimum rotation αt, it can be detected whether there is a blocking process at the beginning of the driving process. It should be noted that the units 41 and 42 may be implemented within the CPU, or may be also implemented as separate units or devices within the controlling unit 40. Thus, the depicted position of the comparing unit 41 within the CPU and the comparing unit 42 outside the CPU is only exemplary.
The controlling unit 40 may also have a predicting unit 50, receiving for example the determined momentum of inertia J and the rotational speed v in order to determine the reaction time of the entire system. For this purpose, the predicting unit 50 may also receive the reaction time Tr of the CPU, wherein the reaction time of the moving parts, that is the shaft and possibly a tool 101 (not shown in Fig. 2) and a coupled screw by using the determined momentum of inertia J and the rotational speed v. Thus, a future position xf can be predicted by the predicting unit 50 and provided with the CPU. Thus, the CPU or the controlling unit 40 may consider this total reaction time in order to consider the further movement caused by the momentum of inertia of the moving parts so as to arrive at the exact stopping position after stopping the driving process. The CPU may further control a signaling unit, which signaling unit may signal the completion of the driving process or may give any other further information useful for the user, for example the remaining time before stopping, any error report or blocking indication, or the like.
Fig. 3 illustrates the relation of the procedural steps. The procedural steps include receiving a pre-setting value, for example the pre-setting rotational value S10, sensing a position value S20, and sensing a torque S30. Further, the amount of movement of the shaft can be determined in S25 by using the sensed position value. Subsequently, an evaluating S40 can be conducted based on the sensed torque and the determined amount of movement of the shaft. Further, a future position of the shaft can be predicted S50, based on the determined amount of movement of the shaft. It should be noted that the predicting step S50 may also be carried out based on a determined momentum of inertia and a reaction time of the electronics, which is not explicitly illustrated in Fig. 3. The controlling of a drive of the power torque tool S60 may be conducted based on the received pre-setting value and the determined amount of movement of the shaft. In addition, a sensed torque may also be used for controlling a drive of the power torque tool.
Fig. 4 illustrates a simplified flow chart of the process. After starting the process, the pre-setting value αp can be input. Then, the actual movement value α can be detected so that afterwards, the actually determined movement value α can be compared with the pre-setting value αp. If the detected value α extends over the pre-setting value αp, the driving process will be stopped. However, if the actual movement value α does not exceed the pre-setting value αp, the procedure goes on and a further detection of the movement value takes place in order to go on with a further comparison. In order to consider the reaction time, α can be predicted and it can be determined whether under the determined reaction time the predicted α corresponds to the pre-set αp so that after stopping down to zero the actual α more or less exactly corresponds to the αp.
Fig. 5 illustrates a more detailed flowchart considering some more inputting values and some more parameters. According to Fig. 5, several values are input, for example the pre-setting value αp, a torque threshold Mt, and a minimum rotational movement αt. A position of the shaft can be sensed at a subsequent order to obtain positional values depending on the respective time t1, t2. Thus, it is possible to determine the actual movement α of the shaft by subtracting the both position values x(tl) and x(t2). Further, the torque M can be detected by the torque detector 22, as well as the momentum of inertia J may be detected by the momentum of inertia sensor 23. In addition, the reaction time of the electronics may be determined to arrive at the reaction time Tr. The actual movement α can be determined by subtracting the both positional values, whereas the speed of the shaft can be determined by calculating Δx divided by Δt. The total reaction time T can be determined as a function of the rotational speed v, the momentum of inertia J, and the reaction time Tr of the electronics. The process may include several comparison sub-processes in order to determine whether the actual movement α has exceeded the pre-setting movement αp, and/or whether the torque M has exceeded the torque threshold Mt and/or whether the predicted movement α as a function of time plus the reaction time T exceeded the actual movement. If the result of the comparison is positive, the system may signal the termination of the driving process. However, if any of the comparisons are negative, the sensing the determining procedure again runs the loop of sensing and calculating and determining.
It should be noted that the invention also may be applied to linear motion tools.
In another exemplary embodiment of the present invention, a computer program or a computer program element is provided that is characterized by being adapted to execute the method steps of the method according to one of the preceding embodiments, on an appropriate system.
The computer program element might therefore be stored on a computer unit, which might also be part of an embodiment of the present invention. This computing unit may be adapted to perform or induce a performing of the steps of the method described above. Moreover, it may be adapted to operate the components of the above described apparatus. The computing unit can be adapted to operate automatically and/or to execute the orders of a user. A computer program may be loaded into a working memory of a data processor. The data processor may thus be equipped to carry out the method of the invention.
This exemplary embodiment of the invention covers both, a computer program that right from the beginning uses the invention and a computer program that by means of an up-date turns an existing program into a program that uses the invention.
Further on, the computer program element might be able to provide all necessary steps to fulfill the procedure of an exemplary embodiment of the method as described above.
According to a further exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is presented wherein the computer readable medium has a computer program element stored on it which computer program element is described by the preceding section.
However, the computer program may also be presented over a network like the World Wide Web and can be downloaded into the working memory of a data processor from such a network. According to a further exemplary embodiment of the present invention, a medium for making a computer program element available for downloading is provided, which computer program element is arranged to perform a method according to one of the previously described embodiments of the invention.
It has to be noted that embodiments of the invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method type claims whereas other embodiments are described with reference to the device type claims. However, a person skilled in the art will gather from the above and the following description that, unless otherwise notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters is considered to be disclosed with this application. However, all features can be combined providing synergetic effects that are more than the simple summation of the features.
It has to be noted that exemplary embodiments of the invention are described with reference to different subject matters. In particular, some exemplary embodiments are described with reference to apparatus type claims whereas other exemplary embodiments are described with reference to method type claims. However, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the apparatus type claims and features of the method type claims is considered to be disclosed with this application.
In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items re-cited in the claims. The mere fact that certain measures are re-cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
A computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.

Reference list:

1: power torque tool
10: drive
20: a shaft
21: position sensor
22: torque sensor
23: moment of inertia determination unit
30: a pre-setting unit
31: key pad
32: wireless connection
40: a controlling unit
41: comparator unit
42: evaluation unit
50: predictor unit
60: signaling unit
101: element/tool
S10: receiving a pre-setting value
S20: sensing a position value
S25: determining an amount of the movement of the shaft, and
S30: sensing a torque
S40: evaluating
S50: predicting a future position of the shaft
S60: controlling a drive of the power torque tool
M: torque
Mt: predetermined torque threshold
J: moment of inertia
α: amount of the movement
αt: pre-setting value of movement,
αp: predetermined rotational movement
x: position value
xf: future position
v: roational speed
Tr: reaction time

Claims

Power torque tool comprising:
- a drive (10),

- a shaft (20),

- a pre-setting unit (30),

- a controlling unit (40),

- a predictor unit (50) for predicting a future position (xf) of the shaft based on a rotational speed of the shaft (20) and a reaction characteristic of the controlling unit (40) and the shaft,
wherein the drive is mechanically coupled to the shaft
wherein the controlling unit is coupled to the drive,
wherein the pre-setting unit is adapted for receiving a pre-setting value of movement (αt) being representative for an amount of movement (α) to be performed by the shaft, and for supplying the pre-setting value to the controlling unit,
wherein the controlling unit is adapted for controlling the drive based on the pre-setting value of movement.
Power torque tool according to claim 1, wherein the amount of movement (α) is a rotational movement and the pre-setting value of movement (αt) is an angular pre-setting value.
Power torque tool according to any one of claims 1 and 2, wherein the shaft (20) is adapted for receiving a tool (101).
Power torque tool according to any one of claims 1 to 3, wherein the power torque tool (1) is a hand held power tool.
Power torque tool according to any one of claims 1 to 4, wherein the power torque tool (1) comprises a position sensor (21) being adapted for sensing a position (x) for determining an amount of the movement (α) of the shaft (20), wherein the position sensor is coupled to the controlling unit (40) for a feed back control, wherein the amount of the movement (α) and the pre-setting value of movement (αt) serve as a base for controlling the drive (10).
Power torque tool according to claim 5, wherein the position value (x) is an angular position value.
Power torque tool according to any one of claims 1 to 6, wherein the controlling unit (40) comprises a comparator unit (41) for comparing the amount of the movement (α) with the pre-setting value of movement (αt) for determining a termination of a driving of the shaft (20).
Power torque tool according to claim 1, wherein the reaction characteristic of the shaft (20) is determined based on the rotational speed of the shaft and the moment of inertia (J) of the shaft.
Power torque tool according to any one of claims 1 to 8, wherein the power torque tool (1) further comprises a torque sensor (22) for sensing the torque (M) as a measure for termination of the rotation of the shaft (20), and an evaluation unit (42) for evaluating whether the shaft has performed a predetermined rotational movement (αp) before it is sensed that a torque (M) at the shaft has extended a predetermined torque threshold (Mt).
Power torque tool according to any one of claims 1 to 9, wherein the power torque tool (1) further comprises a moment of inertia determination unit (23) for determining a moment of inertia (J) of the combination of the shaft (20) and possible elements (101) detachably coupled to the shaft.
Power torque tool according to any one of claims 1 to 10, wherein the power torque tool further comprises a signaling unit (60) for signaling when the amount of movement (α) has reached the pre-setting value of movement (αt).
Method for operating a power torque tool, the method comprising:
receiving (S10) a pre-setting value of movement (αt) being representative for an amount of movement to be performed by a shaft (20) of the power torque tool (1),

sensing (S20) a position value (x) and determining an amount of the movement (α) of the shaft, and

controlling (S60) a drive (10) of the power torque tool based on the pre-setting value and the position value,

predicting (S50) a future position (xf) of the shaft (20) based on a rotational speed of the shaft and a reaction time of a controlling unit (40) and the shaft of the power torque tool (1).
Method for operating a power torque tool according to claim 12 , further comprising sensing a torque (S30) as a measure of termination of the rotation of the shaft (20), and evaluating (S40) whether the shaft has performed a predetermined rotational movement (αp) before it is sensed that a torque (M) at the shaft has extended a predetermined torque threshold (Mt).