Method for learning application shutdown by finding representative waveforms

Abstract

The present invention relates to a method for operating a handheld power tool, the handheld power tool comprising an electric motor, and the method comprises the following method steps: S1 provides comparison information, which comprises the following steps: S1a provides at least one template waveform, wherein the template waveform can be assigned to the working progress of the handheld power tool; S1b provides a consistency threshold; S2 obtains a signal of an operating variable of the electric motor; S3 compares the signal of the operating variable with the template waveform and obtains a consistency evaluation from the comparison, wherein the consistency evaluation is performed at least partially based on the consistency threshold; S4 identifies the working progress at least partially based on the consistency evaluation obtained in method step S3; wherein the providing of the comparison information is performed at least partially based on a learning process. The present invention also relates to a handheld power tool.

Description

Technical Field

[0001] The invention relates to a method for operating a handheld power tool and a handheld power tool designed to carry out the method. In particular, the invention relates to a method for screwing in or out a threaded element using a handheld power tool. Background Art

[0002] A rotary impact driver for tightening threaded elements, such as nuts and screws, is known from the prior art, such as EP 3 202 537 A1. Such a rotary impact driver comprises, for example, a structure in which an impact force in a rotational direction is transmitted to the threaded element by the rotary impact force of a hammer. A rotary impact driver having such a structure comprises a motor, a hammer driven by the motor, an anvil struck by the hammer, and a tool. The rotary impact driver further comprises a position sensor for detecting the position of the motor and a control device coupled to the position sensor. The control device detects the impact of the impact mechanism, calculates the drive angle of the anvil caused by the impact based on the output of the position sensor, and controls the brushless DC motor based on the drive angle.

[0003] An electrically driven tool with an impact mechanism, in which the hammer is driven by a motor, is also known from US Pat. No. 9,744,658. The rotary impact driver also includes a method for recording and reflecting motor parameters.

[0004] When using a rotary impact driver, the user must pay close attention to the progress of the work in order to react accordingly when certain machine properties change, such as when the impact mechanism is started or stopped, for example by stopping the electric motor and / or changing the speed via a manual switch. Since the user is usually unable to react quickly enough or appropriately to the progress of the work, when using a rotary impact driver, for example, screws may be over-rotated during the screwing process and screws may fall out during the screwing process (if they are screwed out at too high a speed).

[0005] Therefore, it is usually desirable to automate the operation to a large extent and to help the customer achieve a completely completed work progress more easily and to ensure that a reliably repeatable, high-quality screwing-in or screwing-out process can be achieved. In addition, the user should be assisted by the appropriate machine-side reactions or routines of the device for the work progress. Examples of such machine-side reactions or routines include, for example, the switching off of the motor, the change of the motor speed or the triggering of feedback to the user.

[0006] Providing such an intelligent tool function can be achieved in particular by identifying the currently active operating state. In the prior art, the identification of the operating state is performed independently of the work progress or the state of the application, for example by monitoring operating variables of the electric motor, such as the rotational speed and the motor current. In this case, the operating variables are evaluated to determine whether certain limit values ​​and / or threshold values ​​are reached. Corresponding evaluation methods work with absolute threshold values ​​and / or signal gradients.

[0007] The disadvantage here is that fixed limit values ​​and / or threshold values ​​are in practice only optimal for one application. As soon as the application changes, the corresponding current value or speed value or its temporal course changes, and the impact detection based on the set limit values ​​and / or threshold values ​​or their temporal course is no longer effective.

[0008] Thus, it can be seen that, for example, an automatic shut-off function based on the detection of an impact operation shuts down reliably in different speed ranges when using self-tapping screws in some applications, but does not shut down in other applications when using self-tapping screws.

[0009] In other methods for determining the operating mode in the case of rotary impact drivers, additional sensors, such as acceleration sensors, are used in order to derive the currently active operating mode from the vibration state of the tool.

[0010] Disadvantages of this method are the additional cost outlay for the sensors and the impairment of the robustness of the handheld power tool, since the number of installed components and electrical connections is greater than for handheld power tools without these sensor systems.

[0011] Furthermore, the simple information about whether the impact mechanism is working is not sufficient to draw reasonable conclusions about the progress of the work. For example, when screwing in a certain woodworking screw, the rotary impact mechanism is activated very early, and the screw has not yet been completely screwed into the material, but the required torque has exceeded the release torque of the rotary impact mechanism. A reaction based purely on the operating state of the rotary impact mechanism (impact operation and non-impact operation) is not sufficient for the correct function of the automation system of the tool, such as shutdown.

[0012] In principle, even in other handheld power tools such as hammer drills, there is the problem of automating the operation to the greatest extent possible, so that the present invention is not restricted to rotary impact drivers. Summary of the invention

[0013] The object of the present invention is to provide a method for operating a handheld power tool which is improved over the prior art and which at least partially eliminates the above-mentioned disadvantages or provides at least one alternative to the prior art. A further object is to provide a corresponding handheld power tool.

[0014] These objects are achieved by means of the corresponding subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the corresponding dependent claims.

[0015] According to the present invention, a method for operating a handheld power tool is disclosed, wherein the handheld power tool comprises an electric motor. The method comprises the following steps:

[0016] S1 provides comparison information, which includes the following steps:

[0017] S1a provides at least one sample waveform, wherein the sample waveform can be assigned to a working progress of the handheld power tool;

[0018] S1b provides the consistency threshold;

[0019] S2 obtains a signal of an operating parameter of the electric motor;

[0020] S3: comparing the signal of the operating parameter with the template waveform and obtaining a consistency evaluation from the comparison, wherein the consistency evaluation is performed at least partially based on the consistency threshold;

[0021] S4 identifies the progress of the work at least partially based on the consistency evaluation obtained in method step S3;

[0022] Wherein providing the comparative information is performed at least in part based on a learning process.

[0023] The method according to the invention effectively assists the user of a handheld power tool in achieving reproducible, high-quality application results. In particular, the method according to the invention enables the user to achieve a completely completed work progress more easily and / or more quickly. In this case, the impact driver machine learns autonomously or partially autonomously at which point it needs to react to the course of the impact detection.

[0024] Some embodiments of the present invention can be categorized as follows:

[0025] 1. An embodiment in which the consistency threshold is provided by a learning process in the sense of implementing one or more exemplary applications;

[0026] 2. An embodiment in which the sample signal is provided by a learning process in the sense of implementing one or more exemplary applications;

[0027] 3. Embodiments in which the consistency threshold value and / or the template signal are provided by a learning process in the sense of reading in one or more screw characteristic curves. In this context, "reading in a screw characteristic curve" can mean, in particular, reading in exemplary signals of operating variables of the electric motor by the hand-held power tool. The screw characteristic curve can be read in, for example, by means of a connection to the Internet and / or the user can create a screw characteristic curve himself by executing the exemplary application.

[0028] All embodiments have the fundamental advantage that applications such as series threading can be carried out quickly, reproducibly and adapted to the requirements of the user, which makes the work of the user easier.

[0029] For example, when assembling furniture (such as kitchen furniture), many identical screws must be driven into a mostly homogeneous material. Here, it is important for the user to drive in the screw heads as evenly as possible (in the sense of a constant high work quality). The present invention can provide the user with assistance that can achieve a constant work quality with the least possible effort. In other words, it can be ensured that all screws are driven in to the same depth, for example by automatically reducing or automatically stopping the motor speed of an impact screwdriver controlled by the method according to the invention.

[0030] A person skilled in the art recognizes that the characteristics of a model waveform include a waveform of a continuously progressing work process. In one embodiment, the model waveform is a model waveform that is typical in terms of conditions, which is typical in terms of conditions for a certain work progress of the handheld power tool. Examples of such work progress include: abutment of a screw head against a fastening base plate, free rotation of a loose screw, start or stop of a rotary impact mechanism of the handheld power tool, and / or impact of the rotary impact mechanism without further rotation of the impacted element or the tool receiving part.

[0031] Approaches for detecting the progress of work by means of operating variables from among the measured variables in the tool, such as the rotational speed of an electric motor, have proven to be particularly advantageous, since this method allows the progress of work to be detected particularly reliably and largely independently of the general operating state of the tool or its application.

[0032] In this case, in particular additional sensor units, such as acceleration sensor units, for checking measured variables within the tool are substantially omitted, so that the method according to the invention is essentially used only for detecting the progress of the work.

[0033] As already mentioned above, in certain embodiments of the invention, the learning process includes the implementation of an exemplary application by the user and / or the reading of at least one exemplary application into a memory that is connected to the machine tool or integrated in the handheld machine tool. In this context, "reading in" is to be understood as reading in one or more screw characteristic curves, in particular exemplary signals of operating parameters of the electric motor. The screw characteristic curves can be read in, for example, by means of a connection to the Internet.

[0034] At least one exemplary application may include reaching a certain operating state of the handheld power tool, for example starting or stopping an impact operation, in particular a rotary impact operation, or reaching a certain screwing depth of a connecting element to be screwed in with the handheld power tool.

[0035] In some embodiments of the invention, the consistency threshold is provided based at least in part on a learning process, and the learning process comprises the following method steps:

[0036] B1 provides at least one sample waveform, wherein the sample waveform can be assigned to a working progress of the handheld power tool;

[0037] B2 obtains a signal of an operating parameter of the electric motor;

[0038] B3 compares the signal of the operating variable with the template waveform at a time when the rotational speed of the electric motor is reduced, in particular when the handheld power tool is stopped by a user, and determines a consistency threshold value assigned to an exemplary application.

[0039] Another embodiment includes: in step B1, at least one sample waveform is provided according to the method according to the present invention as described above.

[0040] The method according to the invention may further comprise: the learning process comprises executing or reading in at least two exemplary applications, preferably a plurality of exemplary applications, and the learning process comprises averaging the consistency threshold from two or more consistency thresholds assigned to these exemplary applications.

[0041] In this way, irregularities that are common in the screwing process (eg variations in carrier material, screwing-in angle, force applied by the user, etc.) are statistically averaged and their influence on the learning process is thus reduced.

[0042] According to the invention, it can be provided that the reading in of at least one exemplary application includes an exemplary signal for reading in operating variables of the electric motor via the handheld power tool. The specific course of such an exemplary signal can also be referred to as a "screwing characteristic curve". It has already been mentioned above that the screwing characteristic curve can be read in, for example, by means of a connection to the Internet and / or that the user can create a screwing characteristic curve himself by executing the exemplary application.

[0043] In some embodiments of the present invention, the method further comprises the following method steps:

[0044] S5 executes a first routine of the handheld power tool at least partially based on the work progress detected in method step S4 .

[0045] In these embodiments, the impact driver reacts autonomously or partially autonomously to the detection of the progress of the work, for example the detection of an impact state.

[0046] Through different routines, one or more system functions can be provided to the user, with which the user can complete an application more simply and / or more quickly. Through the learning process provided according to the invention, the method is highly adaptive and thus highly adapted to the needs of the user.

[0047] In one embodiment, the first routine includes stopping the electric motor taking into account at least one defined and / or predeterminable parameter, in particular predeterminable by a user of the handheld power tool. Examples of such parameters include a time period, a number of revolutions of the electric motor, a number of revolutions of the tool holder, a rotation angle of the electric motor, and a number of impacts of the impact mechanism of the handheld power tool.

[0048] In another embodiment, the first routine includes changing, in particular reducing and / or increasing, the rotational speed of the electric motor. Such a change in the rotational speed of the electric motor can be achieved, for example, by changing the motor current, the motor voltage, the battery current or the battery voltage or by a combination of these measures.

[0049] Preferably, the amplitude / amplitude of the change in the rotational speed of the electric motor can be defined by the user of the handheld power tool. Alternatively or in addition thereto, the change in the rotational speed of the electric motor can also be predetermined by a target value. In this context, the term "amplitude" is also generally understood to mean the size of the change and is not only related to periodic processes.

[0050] In one embodiment, the change in the rotational speed of the electric motor is performed multiple times and / or dynamically, in particular stepwise over time and / or along a characteristic curve of the rotational speed change and / or according to the progress of work of the hand-held power tool, wherein the change in rotational speed is determined at least partially according to the learning process based on the exemplary application.

[0051] In principle, different operating variables can be considered as operating variables recorded by suitable measured value transmitters. It is particularly advantageous here that according to the invention, no additional sensors are required for this purpose, because for example various sensors, preferably Hall sensors, for speed monitoring are already installed in the electric motor.

[0052] Advantageously, the operating variable is the rotational speed of the electric motor or an operating variable that is correlated with the rotational speed. A fixed transmission ratio of the electric motor to the impact mechanism results, for example, in a direct relationship between the motor rotational speed and the impact frequency. Another conceivable operating variable that is correlated with the rotational speed is the motor current. As operating variables of the electric motor, the motor voltage, the Hall signal of the motor, the battery current or the battery voltage are also conceivable, wherein the acceleration of the electric motor, the acceleration of the tool holder or the acoustic signal of the impact mechanism of the handheld power tool are also conceivable operating variables.

[0053] In some embodiments, in method step S2, the signal of the operating parameter is recorded as the time curve of the measured value of the operating parameter, or as the measured value of a parameter of the operating parameter associated with the time curve of the electric motor, such as acceleration, in particular high-order jerk, power, energy, rotation angle of the electric motor, rotation angle of the tool receiving part or frequency.

[0054] In the last-mentioned embodiment, it can be ensured that a constant periodicity of the signal to be investigated is obtained, which is independent of the motor speed.

[0055] If the signal of the operating variable is recorded in method step S2 as the time curve of the measured value of the operating variable, then in step S2a following method step S2 the time curve of the measured value of the operating variable is converted into a curve of a variable of the measured value of the operating variable with respect to the electric motor which is associated with the time curve, based on the fixed transmission ratio of the transmission. The same advantages are thus obtained as in the case of direct receipt of the signal of the operating variable over time.

[0056] Preferably, the work progress of the first routine is output to the user of the handheld machine tool using an output device of the handheld machine tool. "Outputting by means of an output device" can be understood in particular as displaying or recording the work progress. Here, recording can also be analyzing and / or storing the work progress. This includes, for example, also storing a plurality of screwing processes in a memory.

[0057] In one embodiment, the first routine and / or characteristic parameters of the first routine can be set and / or presented by a user via an application (“App”) or a user interface (Human-Machine Interface, HMI).

[0058] Furthermore, in one embodiment, the HMI may be disposed on the machine itself; while in other embodiments, the HMI may be disposed on an external device, such as a smartphone, tablet computer, and / or computer.

[0059] In an embodiment of the invention, the first routine includes visual, auditory and / or tactile feedback to the user.

[0060] Preferably, the model waveform is an oscillation curve, for example an oscillation curve about a mean value, in particular an oscillation curve substantially in the form of a trigonometric function. In this case, the model waveform can, for example, represent an ideal impact operation of a hammer on an anvil of a rotary impact mechanism, wherein the ideal impact operation is preferably an impact without further rotation of the tool spindle of the hand-held power tool.

[0061] In one embodiment of the invention, in method step S3 , the signals of the operating variables are compared by means of a comparison method with regard to whether at least one predefined consistency threshold value is met.

[0062] Preferably, the comparison method comprises at least one frequency-based comparison method and / or at least one contrast comparison method.

[0063] In this case, it can be determined at least partially by means of a frequency-based comparison method, in particular a bandpass filter and / or a frequency analysis, whether a work progress to be identified has been recognized in the signal of the operating variable.

[0064] In one specific embodiment, the frequency-based comparison method comprises at least a bandpass filter and / or a frequency analysis, wherein the predefined threshold value is at least 90%, in particular 95%, and in particular exactly 98% of the predefined limit value.

[0065] In a bandpass filter, for example, the recorded signal of the operating variable is filtered through a passband whose pass range corresponds to the template waveform. In the presence of a decisive work progress to be identified, a corresponding amplitude value will appear in the resulting signal. The predetermined threshold value of the bandpass filter can thus be at least 90%, in particular 95%, and in particular 98% of the corresponding amplitude in the work progress to be identified. The predetermined limit value can be the corresponding amplitude of the ideal work progress to be identified in the resulting signal.

[0066] By means of known frequency-based frequency analysis comparison methods, a previously determined model waveform, for example a frequency spectrum of the work progress to be identified, can be searched for in the recorded signal of the operating variable. The corresponding amplitude of the work progress to be identified will appear in the recorded signal of the operating variable. The predetermined threshold value of the frequency analysis can be at least 90%, in particular 95%, and in particular 98% of the corresponding amplitude in the work progress to be identified. The predetermined limit value can be the corresponding amplitude in the recorded signal of the ideal work progress to be identified. A suitable segmentation of the recorded signal of the operating variable may be necessary in this case.

[0067] In one embodiment, the comparative comparison method includes at least one parameter evaluation And / or cross-correlation, wherein the threshold value is predefined as a signal of the operating variable that corresponds to the template waveform by at least 40%.

[0068] The measured signal of the operating parameter can be compared with the template waveform by means of a comparative comparison method. The measured signal of the operating parameter is obtained in such a way that it has a finite signal length substantially equal to the template waveform. The comparison of the template waveform with the measured signal of the operating parameter can be output as a finite length, in particular a discrete or continuous signal. According to the degree of consistency of the comparison or the deviation of the comparison, a result can be output: whether there is a work progress to be identified. When the measured signal of the operating parameter is at least 40% consistent with the template waveform, there is a work progress to be identified. It is also conceivable that the comparison method can output the degree of mutual identity as a comparison result by means of the comparison of the measured signal of the operating parameter with the template waveform. Here, at least 60% of mutual identity can be used as a criterion for the existence of a work progress to be identified. The starting point here is that the lower limit of the consistency is 40%, and the upper limit of the consistency is 90%. Correspondingly, the upper limit of the deviation is 60%, and the lower limit of the deviation is 10%.

[0069] In the parameter evaluation, a comparison between a previously determined model waveform and the signal of the operating variable can be performed in a simple manner. For this purpose, evaluation parameters of the model waveform are identified in order to adapt the model waveform to the measured signal of the operating variable. By means of a comparison between the previously determined evaluation parameters of the model waveform and the limit values, a conclusion can be drawn that there is a work progress to be identified. A further evaluation of the comparison result can then be performed: whether a predetermined threshold value has been reached. The evaluation is either a quality determination of the evaluation parameters or a consistency between the determined model waveform and the detected signal of the operating variable.

[0070] In another embodiment, method step S3 includes a step S3a of quality determination of the recognition of a model waveform in the signal of the operating variable, wherein in method step S4 the work progress is detected at least partially based on the quality determination. The adaptation quality of the evaluation parameter can be determined as a measure of the quality determination.

[0071] In method step S4 , it can be determined at least partially with the aid of a quality determination, in particular a quality measure, whether a work progress to be identified has been recognized in the signal of the operating variable.

[0072] In addition or as an alternative to the quality determination, method step S3 may include the identification of a model waveform and a comparative determination of the signal of the operating variable. The comparison of the evaluation parameter of the model waveform with the measured signal of the operating variable may be, for example, 70%, in particular 60%, completely, in particular 50%. In method step S4, it is determined at least partially based on the comparative determination whether there is a work progress to be identified. The determination whether there is a work progress to be identified can be made at a predetermined threshold value of at least 40% agreement between the measured signal of the operating variable and the model waveform.

[0073] In the cross correlation, a comparison between a previously determined model waveform and a measured signal of an operating variable can be performed. In the cross correlation, a previously determined model waveform can be correlated with a measured signal of an operating variable. In the correlation of the model waveform with the measured signal of the operating variable, the degree of consistency of the two signals can be determined. The degree of consistency can be, for example, 40%, in particular 50%, or even 60%.

[0074] In method step S4 of the method according to the invention, the identification of the work progress can be carried out at least partially based on the cross-correlation of the template waveform with the measured signal of the operating variable. The identification can be based at least partially on a predetermined threshold value of at least 40% agreement between the measured signal of the operating variable and the template waveform.

[0075] In one specific embodiment, the consistency threshold value may be determined by a user of the handheld power tool and / or may be predefined at the factory.

[0076] In a further embodiment, the handheld power tool is an impact driver, in particular a rotary impact driver, and the work progress is starting or stopping an impact operation, in particular a rotary impact operation.

[0077] In one embodiment, the consistency threshold can be selected by the user based on factory-defined pre-selections of the application of the handheld power tool. This can occur, for example, via a user interface / such as an HMI (Human-Machine Interface), such as a mobile device, in particular a smartphone and / or a tablet computer.

[0078] In particular, in method step S1 , the template waveform is variably determined, in particular by a user. In this case, the template waveform is assigned to the work progress to be identified, so that the user can predetermine the work progress to be identified.

[0079] Advantageously, in method step S1 the template waveform is predefined, in particular factory-defined. In principle, it is conceivable that the template waveform is stored or stored in the device and alternatively and / or additionally provided to the handheld power tool, in particular from an external data device.

[0080] A person skilled in the art will recognize that the method according to the invention makes it possible to identify the progress of work independently of at least one desired rotational speed of the electric motor, at least one starting feature of the electric motor and / or at least one charge state of the energy supply of the handheld power tool, in particular a battery.

[0081] The signal of the operating variable is to be understood here as a sequence of measured values ​​in time. Alternatively and / or additionally, the signal of the operating variable can also be a spectrum. Alternatively and / or additionally, the signal of the operating variable can also be supplemented by processing, for example, smoothing, filtering, adaptation, etc.

[0082] In a further embodiment, the signal of the operating variable is stored as a sequence of measured values ​​in a memory, in particular a memory of the handheld power tool, preferably a ring memory.

[0083] In one method step, the work progress to be identified is identified based on less than ten impacts of the impact mechanism of the handheld power tool, in particular based on less than ten impact oscillation cycles of the electric motor, preferably based on less than six impacts of the impact mechanism of the handheld power tool, in particular based on less than six impact oscillation cycles of the electric motor, and most preferably based on less than four impacts of the impact mechanism of the handheld power tool, in particular based on less than four impact oscillation cycles of the electric motor. Here, the impact of the impact mechanism is understood to be an axially, radially, tangentially and / or circumferentially directed impact of the impact mechanism striker, in particular a hammer, on the impact mechanism body, in particular anvil. The impact oscillation cycle of the electric motor is associated with an operating variable of the electric motor. The impact oscillation cycle of the electric motor can be determined based on operating variable fluctuations in the signal of the operating variable.

[0084] A further subject of the invention is a handheld power tool having an electric motor, a measured value recorder of operating variables of the electric motor and a control unit, wherein the handheld power tool is advantageously an impact driver, in particular a rotary impact driver, and is designed to carry out the above-described method.

[0085] The electric motor of the handheld machine tool sets the input spindle into rotation, wherein the output spindle is connected to the tool receptacle. The anvil is connected to the output spindle in a rotationally fixed manner, and the hammer is connected to the input spindle in such a way that it performs intermittent motion along the axial direction of the input spindle and intermittent rotational motion around the input spindle based on the rotational motion of the input spindle, wherein the hammer intermittently strikes the anvil in this way and thereby outputs impact momentum and angular momentum to the anvil and thereby to the output spindle. The first sensor transmits a first signal, for example, for determining the motor rotation angle, to the control unit. In addition, the second sensor can transmit a second signal for determining the motor speed to the control unit. .

[0086] Advantageously, the handheld power tool has a memory unit in which a plurality of values ​​can be stored.

[0087] In another embodiment, the handheld power tool is a battery-operated handheld power tool, in particular a battery-operated rotary impact screwdriver. In this way, flexible and power-network-independent use of the handheld power tool can be ensured.

[0088] Advantageously, the handheld power tool is an impact screwdriver, in particular a rotary impact screwdriver, and the work progress to be detected is the contact of the screw head with the fastening base, the free rotation of a loose screw, the starting or stopping of the rotary impact mechanism of the handheld power tool and / or the impact of the rotary impact mechanism without further rotation of the impacted element or the tool holder.

[0089] The detection of the impact of the impact mechanism of the handheld power tool, in particular the impact oscillation period of the electric motor, can be realized, for example, by using a fast fitting algorithm, by means of which the impact detection can be evaluated in less than 100 milliseconds, in particular less than 60 milliseconds, and in particular less than 40 milliseconds. The method according to the invention mentioned here makes it possible to detect the progress of the work for basically all the above-mentioned application cases and the tightening of loose or tight fastening elements in the fastening carrier.

[0090] The invention largely eliminates complex signal processing methods such as filtering, signal looping, system models (static and adaptive) and signal tracking.

[0091] Furthermore, the invention allows for a faster recognition of the impact operation or the progress of the work, thereby evoked a faster reaction of the tool. This applies in particular to the number of impacts that have passed after the use of the impact mechanism until the recognition and in certain operating situations, such as the start-up phase of the drive motor. In this case, it is also not necessary to limit the effectiveness of the tool, for example by reducing the maximum drive speed. Furthermore, the algorithm function is also independent of other influencing factors, such as the desired speed and the battery charge state.

[0092] In principle, no additional sensor means (eg, acceleration sensor) is required, but these evaluation methods can also be used for signals of other sensor means. In addition, in other motor designs, for example, without rotational speed detection, the methods can also be used in other signals.

[0093] In a preferred embodiment, the handheld power tool is a battery screwdriver, an electric drill, an impact drill or an electric hammer, wherein drill bits, drill crowns or different bit attachments can be used as tools. The handheld power tool according to the invention is in particular designed as an impact driver tool, wherein a higher peak torque is generated by the pulsed release of motor energy for screwing in or screwing out screws or nuts. In this context, the transmission of electrical energy is understood to mean in particular that the handheld power tool transmits energy via a battery and / or a power cord on the main body.

[0094] In addition, according to the selected embodiment, the screwdriver tool can be flexibly configured in the direction of rotation. In this way, the method mentioned can be used for both screwing in a screw or nut and also for screwing it out.

[0095] In the context of the present invention, “ascertaining” is to be understood in particular as measuring or recording, wherein “recording” is to be understood in the sense of measuring and storing, and furthermore, “ascertaining” is to include any signal processing of the measured signal.

[0096] Furthermore, "determining" is also to be understood as identifying or detecting, wherein an unambiguous assignment is to be achieved. "Recognition" is to be understood as the recognition of a partial agreement with a template, which can be achieved, for example, by fitting the signal to a template, Fourier analysis or the like. "Partial agreement" is to be understood as a fit with an error less than a predefined threshold value, in particular less than 30%, completely in particular less than 20%.

[0097] Further features, application possibilities and advantages of the present invention are apparent from the following description of the exemplary embodiments of the present invention shown in the drawings. It should be noted that the features described or shown in the drawings may form the subject matter of the present invention alone or in any combination, and have only the described features independently of their overview in the claims or the reference relationship of the claims or their representation and display in the description and drawings and should not be considered as any form of restriction of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] The present invention will be explained in detail below based on preferred embodiments. The accompanying drawings are schematic and show:

[0099] Figure 1 A schematic diagram of an electric handheld power tool is shown.

[0100] FIG. 2( a ) shows the working progress of an exemplary application and the corresponding signals of operating parameters.

[0101] FIG2(b) shows the consistency of the signal shown in FIG2(a) of the operating parameter with the sample signal.

[0102] Figure 3 The operating progress of an exemplary application and two corresponding signals of operating parameters are shown.

[0103] Figure 4 The course of a signal of an operating variable according to two specific embodiments of the present invention is shown.

[0104] Figure 5 The course of a signal of an operating variable according to two specific embodiments of the present invention is shown.

[0105] Figure 6 The operating progress of an exemplary application and two corresponding signals of operating parameters are shown.

[0106] Figure 7 The signal curves of two operating variables according to two specific embodiments of the present invention are shown.

[0107] Figure 8 The signal curves of two operating variables according to two specific embodiments of the present invention are shown.

[0108] FIG. 9 shows a schematic diagram of two different graphs of a signal of an operating variable.

[0109] FIG10( a ) shows the signals of the operating parameters.

[0110] FIG. 10( b ) shows the amplitude function of the first frequency contained in the signal of FIG. 10( a ).

[0111] FIG. 10( c ) shows the amplitude function of the second frequency contained in the signal of FIG. 10( a ).

[0112] FIG. 11 shows an overview of the signals of the operating parameters and the output signal of the bandpass filter, based on a sample signal.

[0113] FIG. 12 shows an overview of the output of the signal and frequency analysis of the operating parameters, based on a sample signal.

[0114] FIG. 13 shows an overview of the signals of the operating parameters and the sample signals used for parameter estimation.

[0115] FIG. 14 shows an overview of the signals of the operating parameters and the sample signals used for the cross-correlation. DETAILED DESCRIPTION

[0116] Figure 1 A handheld power tool 100 according to the invention is shown, which has a housing 105 with a handle 115. According to the embodiment shown, the handheld power tool 100 can be mechanically and electrically connected to a battery pack 190 for power supply independent of a power supply network. Figure 1 In the embodiment, the handheld power tool 100 is exemplarily configured as a battery-operated rotary impact driver. However, it should be noted that the present invention is not limited to battery-operated rotary impact drivers, but can be applied in principle to any handheld power tool 100 that needs to identify the progress of work, such as a hammer drill.

[0117] An electric motor 180 and a transmission 170, which are supplied with current by a battery pack 190, are arranged in the housing 105. The electric motor 180 is connected to the input spindle via the transmission 170. In addition, a control unit 370 is arranged in the housing 105 in the region of the battery pack 190, which acts on the electric motor 180 and the transmission 170 in order to control and / or regulate the electric motor 180 and the transmission 170, for example, by means of a set motor speed n, a selected angular momentum, a desired transmission gear x or the like.

[0118] The electric motor 180 can be actuated, i.e. started and switched off, for example, by means of a manual switch 195 and can be any type of motor, for example an electronically commutated motor or a DC motor. In principle, the electric motor 180 can be electronically controlled or regulated in such a way that reverse operation can be achieved and a desired motor speed n and a desired angular momentum can be preset. The mode of operation and the design of suitable electric motors are sufficiently known from the prior art, so that they are not described in detail here for the sake of brevity of the description.

[0119] The tool receiver 140 is rotatably supported via the input spindle and the output spindle in the housing 105. The tool receiver 140 is used to receive a tool and can be directly molded onto the output spindle or connected to the output spindle in the form of a plug-in assembly.

[0120] The control unit 370 is connected to a power source and is designed such that the control unit can electronically control the electric motor 180 in a controlled or regulated manner by means of different current signals. The different current signals are used for different angular momentums of the electric motor 180, wherein the current signals are transmitted to the electric motor 180 via control lines. The power source can be designed, for example, as a battery or, as in the illustrated embodiment, as a battery pack 190 or as a mains connection.

[0121] Furthermore, operating elements (not shown in detail) may be provided in order to set different operating modes and / or directions of rotation of electric motor 180 .

[0122] According to one aspect of the present invention, a method for operating a handheld power tool 100 is provided, by means of which, for example, Figure 1 The work progress of the handheld power tool 100 in use, for example in a screwing or unscrewing process, is shown, wherein comparative information is provided at least partially based on a learning process. In this context, "providing" is understood to mean making the corresponding features available in an internal or external memory of the handheld power tool 100. Various aspects of the learning process are described in more detail below.

[0123] In an embodiment of the invention, as a follow-up to the determination of the progress of the work, a corresponding reaction or routine is triggered on the machine side. This allows a reliably repeatable and high-quality screwing-in or screwing-out process to be achieved. Aspects of the method are based in particular on the study of the waveform and the determination of the degree of consistency of the waveform, which determination can correspond, for example, to an evaluation of the further rotation of an element driven by the handheld power tool 100, such as a screw.

[0124] 2 shows an exemplary signal of an operating variable 200 of an electric motor 180 of a rotary impact driver, which or a similar signal would occur if the rotary impact driver was used as intended. Although the following embodiments relate to a rotary impact driver, they are also applicable within the scope of the present invention to other handheld power tools 100, such as a hammer drill.

[0125] In the embodiment of FIG. 2 , time is plotted on the abscissa x as a reference variable. However, in alternative embodiments, time-related variables may also be used as reference variables, such as the rotation angle of the tool receiving part 140, the rotation angle of the electric motor 180, acceleration, jerk (Ruck), in particular higher-order jerk, power or energy. In the figure, the motor speed n acting at each moment is plotted on the ordinate f(x). Instead of the motor speed, other operating variables related to the motor speed may also be selected. In alternative embodiments of the present invention, f(x) represents, for example, a signal of the motor current.

[0126] The motor speed and the motor current are operating variables which are usually detected in the handheld power tool 100 and which are detected without additional effort by the control unit 370. The ascertainment of the signal of the operating variable 200 of the electric motor 180 is referred to as method step S2 within the scope of the present disclosure. In a preferred embodiment of the present invention, the user of the handheld power tool 100 can select the operating variable based on which the method of the present invention should be carried out.

[0127] FIG2(a) shows the use of a loose fastening element, such as a screw 900, in a fastening carrier 902, such as a wooden board. FIG2(a) shows that the signal includes a first region 310, which is characterized by a monotonically increasing motor speed and a relatively constant motor speed region (also referred to as a plateau). In FIG2(a), the intersection of the abscissa x and the ordinate f(x) corresponds to the start of the rotary impact screwdriver during the screwing process.

[0128] In the first region 310, the screw 900 encounters relatively little resistance in the fastening carrier 902, and the torque required for screwing in is lower than the disengagement torque of the rotary impact mechanism. Thus, the trend of the motor speed in the first region 310 corresponds to the operating state of the screwdriver without impact.

[0129] As can be seen in FIG. 2( a ), in region 322 the head of the screw 900 does not rest against the fastening carrier 902 , which means that the screw 900 driven by the rotary impact driver rotates further with each impact. This additional rotation angle decreases during the further operation, which is reflected in the figure by the reduced cycle duration. In addition, further screwing in can be reflected by the average reduced rotation speed.

[0130] Then, if the head of screw 900 reaches base plate 902, a higher torque and thus more impact energy are required for further screwing in. However, since handheld power tool 100 does not provide more impact energy, screw 900 is not rotated further or is only rotated further by a much smaller rotation angle.

[0131] The rotary impact operation performed in the second region 322 and the third region 324 is characterized by an oscillating profile of the signal of the operating variable 200, wherein the waveform of the oscillation can be, for example, a trigonometric function or another form of oscillation. In the present case, the oscillation has a profile that can be called a modified trigonometric function. In the impact screwing operation, the characteristic waveform of the signal of the operating variable 200 is formed by the expansion and idling of the impact mechanism striker and the system chain between the impact mechanism and the electric motor 180, in particular the transmission 170.

[0132] That is, the waveforms associated with the respective work progress, for example the impact operation, are characterized in principle by certain representative features, which are at least partially predetermined by the intrinsic properties of the rotary impact driver. In the method according to the invention, based on this knowledge, comparison information is provided in step S1, wherein at least one model waveform 240 is provided in step S1a. In this case, the model waveform 240 can be associated with a work progress, which is, for example, the point at which the head of the screw 900 comes into contact with the fastening carrier 902, and in connection with some embodiments of the invention, the model waveform 240 is also referred to as a model waveform typical in terms of the state. In other words, the model waveform 240 contains features that are typical for the work progress, such as the presence of an oscillation curve, an oscillation frequency or an oscillation amplitude or a respective signal sequence in continuous form, quasi-continuous form or discrete form.

[0133] In other applications, the work progress to be detected is characterized by a waveform other than an oscillation, for example by a discontinuity or a rate of increase in the function f(x). In these cases, instead of an oscillation, a typical model waveform in terms of the state is characterized by these parameters.

[0134] At this point it is mentioned that in method step S1 b further comparison information is provided, namely a consistency threshold value which will be described in more detail below.

[0135] In a preferred embodiment of the method of the present invention, in method step S1, a state-typical model waveform 240 is determined by the user. The state-typical model waveform 240 can also be stored or stored in the device. In an alternative embodiment, the state-typical model waveform can be provided to the handheld power tool 100, for example, by an external data device, alternatively and / or additionally.

[0136] In method step S3 of the method according to the invention, the signal of the operating variable 200 of the electric motor 180 is compared with a state-typical model waveform 240. "Comparison" is to be interpreted broadly and in the sense of signal analysis in the context of the present application, so that the result of the comparison can also be, in particular, that the signal of the operating variable 200 of the electric motor 180 partially or gradually matches the model waveform 240, wherein the degree of consistency of the two signals can be determined by different mathematical methods, which will be mentioned later.

[0137] Furthermore, in step S3 , an evaluation of the consistency of the signal of operating variable 200 of electric motor 180 with template waveform 240 which is typical for the state is ascertained from the comparison, and a conclusion is drawn from this regarding the consistency of the two signals.

[0138] Figure 2(b) shows a curve of the function q(x) of the consistency evaluation 201 corresponding to the signal of the operating parameter 200 of Figure 2(a), which shows the value of the consistency between the signal of the operating parameter 200 of the electric motor 180 and the typical sample waveform 240 in terms of the state at each point on the horizontal axis x.

[0139] In the present example of screwing in a screw 900, the evaluation is considered for determining the extent of further rotation during the impact. The sample waveform 240 provided in step S1a corresponds in this example to an ideal impact without further rotation, i.e. a state in which the head of the screw 900 rests on the surface of the fastening carrier 902, as shown in region 324 of FIG. 2(a). Accordingly, a high consistency of the two signals is obtained in region 324, which is reflected by a constant high value of the function q(x) of the consistency evaluation 201. In region 310, where there is a large rotation angle of the screw 900 with each impact, only a small consistency value is achieved. The less the screw 900 is further rotated during the impact, the higher the consistency, which can be seen from the following: the function q(x) of the consistency evaluation 201 already shows a continuously increasing consistency value in the case of using an impact mechanism in region 322, which is characterized by the fact that the rotation angle of the screw 200 with each impact is continuously reduced due to the increased screw-in resistance.

[0140] As can be seen in FIG. 2 , the consistency evaluation 201 of the signal is very suitable for distinguishing impacts due to its more or less step-like character, wherein this step change is caused by a more or less step-like change in the further rotation angle of the screw 900 at the end of the exemplary work process. According to the invention, the identification of the progress of the work is carried out at least in part based on the comparison of the consistency evaluation 201 with the consistency threshold value provided in step S1a, which is represented by the dashed line 202 in FIG. 2 (b). In the example of FIG. 2 (b), the intersection point SP of the function q(x) of the consistency evaluation 201 and the line 202 is assigned to the progress of the work: the head of the screw 900 is in contact with the surface of the fastening carrier 902.

[0141] In method step S4 of the method according to the invention, the work progress is identified at least partially based on the consistency evaluation 201 ascertained in method step S3 .

[0142] It should be pointed out at this point that the described functionality is not limited to the screw-in situation but can also include application in the screw-out situation.

[0143] As already explained above, according to the present invention, the provision of the comparison information in step S1 is carried out at least partially based on a learning process. In an embodiment of the present invention, the learning process includes the implementation or reading in of at least one exemplary application of the handheld power tool 100, wherein the at least one exemplary application includes reaching a certain working progress of the handheld power tool 100, for example reaching a state in which the head of the screw 900 rests on the surface of the fastening carrier 902, as shown in area 324 of FIG. 2 (a).

[0144] In some embodiments, the template signal 240 is provided by a learning process, wherein the learning process comprises the following method steps:

[0145] A1 determines a signal of an operating variable 200 ′ of an electric motor 180 according to an exemplary application;

[0146] A2 determining a sample waveform 240' assigned to an exemplary application based on the signal of the operating variable 200' during the reaching of a certain work progress, in particular at the time when a certain work progress is reached;

[0147] A2 ′ determines a sample waveform 240 ′ assigned to the exemplary application as a function of the signal of operating variable 200 ′ which is present at the time when the determined work progress is reached.

[0148] Advantageously, the learning process can include the implementation or reading in of at least two exemplary applications and the ascertainment of a sample waveform 240 from two or more sample waveforms 240' associated with these exemplary applications, for example by averaging or other statistical operations. The sample waveform 240 ascertained in this way is, for example, stored in the device and provided in a subsequent application in the above-mentioned step S1a within the scope of the method according to the invention.

[0149] That is, the basis of this embodiment is learning through application. In short, the user performs one or more exemplary applications, and the handheld power tool 100 learns the sample waveform 240' in which the user stops or reduces the rotation speed of the handheld power tool 100. In subsequent applications, if a consistency threshold value predetermined by the factory or the user or learned by the user is reached during the consistency evaluation in step S3, the handheld power tool 100 automatically stops or reduces the rotation speed. Here, the rotation speed curve in the sense of a routine that should be carried out when the work progress to be identified is reached can also be learned with the help of the exemplary application.

[0150] By changing the template signal 240, a high degree of consistency between the measured information of the operating variable 200 and the template signal 240 is identified while the screwing conditions remain unchanged, and the handheld power tool 100 can implement a determined routine or a routine to be selected by the user when a set consistency threshold is reached, which will be described in more detail later.

[0151] In another embodiment, instead of the template signal 240 , a consistency threshold is provided at least partially based on the learning process, wherein the learning process comprises the following method steps:

[0152] B1 provides at least one sample waveform 240 ″, wherein the sample waveform 240 ″ can be assigned to a working progress of the handheld power tool 100 ;

[0153] B2 determines the signal of the operating variable 200 ′ of the electric motor 180 ;

[0154] B3 At the time when the rotational speed of electric motor 180 is reduced, in particular when handheld power tool 100 is stopped by the user, the signal of operating variable 200 ′ is compared with template waveform 240 ″ and a consistency threshold value assigned to the exemplary application is determined.

[0155] Preferably, in step B1 , at least one sample waveform is provided according to one of the above-described methods, ie again by a learning process.

[0156] Advantageously, in an embodiment in which a consistency threshold is provided based on a learning process, the learning process comprises implementing or reading in at least two exemplary applications, and the learning process comprises calculating an average value of the consistency threshold from two or more consistency thresholds assigned to these exemplary applications, wherein the term "average value" here simply represents appropriate statistical processing of these at least two exemplary applications.

[0157] In simple terms, in this embodiment, the user executes one or more exemplary applications, and the handheld power tool 100 learns the threshold value at which the user stops or reduces the rotation speed of the handheld power tool 100. In subsequent applications, the handheld power tool 100 automatically stops or reduces the rotation speed based on the stored or calculated average value. Here, the rotation speed curve can also be learned with the help of the exemplary applications.

[0158] In the two embodiments described above, in which sample waveform 240 or a consistency threshold value is determined from an exemplary application, provision may actually be made for the learning process to be initiated by selecting a learning mode of handheld power tool 100 .

[0159] In another embodiment, the reading in of at least one exemplary application comprises the reading in of exemplary signals of operating variables of the electric motor 180 by the handheld power tool 100. As already mentioned above, the consistency threshold value and the template signal or both can be provided by a learning process in the sense of reading in one or more screw characteristic curves. In this case, reading in a screw characteristic curve can in particular mean reading in exemplary signals of operating variables of the electric motor by the handheld power tool. The screw characteristic curve can be read in, for example, by means of a connection to the Internet, and / or the user can create a screw characteristic curve himself by executing the exemplary application.

[0160] That is, according to the present invention, the working progress of an element driven by a rotary impact driver can be evaluated and a routine following the working progress can be initiated by distinguishing or comparing waveforms, wherein a part of the evaluation criteria for the consistency of the waveform used here (i.e., the template waveform 240) or the compared waveforms (i.e., the consistency threshold) or both are at least partially provided by a learning process.

[0161] Advantageously, the determination of the work progress learned in the sense of the above-described execution is supplemented by a further method step S5, in which a first routine of the handheld power tool 100 is executed at least partially based on the work progress identified in method step S4, as described below. It is assumed in each case that the work progress to be identified, which results in the handheld power tool executing the above-described first routine in method step S5, has been defined by the learning process as described above by parameters, which are the template waveform 240 and / or the consistency threshold value.

[0162] Although the speed is reduced when switching to impact mode, it is difficult to prevent the screw head from penetrating into the material, for example in the case of small carpentry screws or self-tapping screws. The reason for this is that the impact by the impact mechanism leads to high spindle speeds, even at increased torque.

[0163] This is manifested in Figure 3 2, for example, time is plotted on the abscissa x, while the motor speed is plotted on the ordinate f(x) and the torque g(x) is plotted on the ordinate g(x). The graphs f and g thus illustrate the course of the motor speed f and the torque g over time. Figure 3 In the lower region of FIG. 2 , different states of the process of screwing carpenter screws 900 , 900 ′ and 900 ″ into the fastening carrier 902 are schematically shown, similar to the illustration in FIG. 2 .

[0164] In the operating state "no impact" indicated by reference numeral 310 in the figure, the screw rotates at a high speed f and a low torque g. In the operating state "impact" characterized by reference numeral 320, the torque g increases rapidly, while the speed f decreases only slightly, as already indicated above. Figure 3 Region 310 ′ in φ represents a region in which the shock detection explained in conjunction with FIG. 2 takes place.

[0165] In order to prevent, for example, the screw head of the screw 900 from entering the fastening carrier 902, according to the present invention, in method step S5, a suitable application-related routine or reaction of the tool is implemented at least partly based on the work progress identified in method step S4, such as shutting down the machine, changing the rotational speed of the electric motor 180 and / or providing visual, auditory and / or tactile feedback to the user of the handheld machine tool 100.

[0166] In one embodiment of the present invention, the first routine includes stopping electric motor 180 taking into account at least one defined and / or predefinable parameter, in particular predefinable by a user of the handheld power tool.

[0167] For this purpose, for example, Figure 4 Schematically shown in FIG. 3 is the stopping of the tool immediately after the impact recognition 310 ′, thereby assisting the user in preventing the screw head from entering the fastening carrier 902 . In the figure, this is represented by the branch f′ of the graph line f which drops rapidly after the region 310 ′.

[0168] An example of a defined and / or predeterminable parameter, in particular a parameter that can be predetermined by a user of the handheld power tool 100, is a time defined by the user after which the tool is stopped, which is Figure 4 Through time period T StoppAnd the related branch f" of the graph f is presented. In an ideal case, the handheld power tool 100 stops just in such a way that the screw head is flush with the screw contact surface. Since the time until this happens varies depending on the application, the time period T Stopp It is advantageous to be able to be defined by the user.

[0169] Alternatively or additionally, in embodiments of the invention it is provided that the first routine includes a change, in particular a reduction and / or increase in the rotational speed, in particular an expected rotational speed, of electric motor 180 and thus also a change, in particular a reduction and / or increase in the spindle speed after impact detection. Figure 5 , an embodiment of the reduction in speed is shown. The handheld power tool 100 is first operated in the “no impact” operating state 310, which is characterized by the course of the motor speed represented by the graph f. After the impact is detected in the area 310', the motor speed is reduced by a certain amplitude in the example, which is represented by the graph f' or f".

[0170] In an embodiment of the present invention, the user can adjust Figure 5 The branch line f" of the graph f is composed of Δ D The magnitude or size of the change in the rotational speed of the electric motor 180 is characterized by the reduced rotational speed, which gives the user more time to react when the screw head approaches the surface of the fastening carrier 902. As soon as the user deems that the screw head is sufficiently flush with the contact surface, he can stop the handheld power tool 100 with the aid of the switch. Compared with stopping the handheld power tool 100 after the impact detection, the change in the motor speed (in Figure 5 To reduce) has the advantage that, by having the user determine the shutdown, the routine is largely independent of the application.

[0171] In an embodiment of the present invention, the amplitude Δ of the change in the rotation speed of the electric motor 180 is D The target value for the rotational speed of electric motor 180 and / or the rotational speed of electric motor 180 can be defined by a user of handheld power tool 100 , which increases the flexibility of the routine in terms of suitability for various application cases.

[0172] In an embodiment of the present invention, the speed of the electric motor 180 is changed multiple times and / or dynamically. In particular, it can be provided that the speed of the electric motor 180 is changed stepwise in time and / or along a characteristic curve of the speed change and / or according to the progress of the work of the portable power tool 100.

[0173] Examples for this include, in particular, a combination of a speed reduction and a speed increase. Furthermore, different routines or combinations thereof can be executed with a time offset relative to the impact detection. Furthermore, the invention also includes embodiments in which a time offset is provided between two or more routines. If, for example, the motor speed is reduced immediately after the impact detection, the motor speed can be increased again after a certain time value. Furthermore, embodiments are provided in which not only the different routines themselves but also the time offsets between the routines are predetermined by the characteristic curve.

[0174] As mentioned at the outset, the invention includes an embodiment in which the operating progress is characterized by a switch from the operating state "bump" in the region 320 to the operating state "no bump" in the region 310, as in Figure 6 As shown in .

[0175] Such a transition of the operating state of the handheld power tool occurs, for example, during a work process in which the screw 900 is loosened from the fastening carrier 902, that is, during the unscrewing process. Figure 6 Schematically shown in the lower area of ​​. Figure 3 Similar to Figure 6 The graph line f also represents the rotation speed of the electric motor 180 , and the graph line g represents the torque.

[0176] As already explained in conjunction with other specific embodiments of the present invention, here too, the state of the handheld power tool, in the present case the operating state of the impact mechanism, is detected by detecting a characteristic waveform.

[0177] In the "Shock" operating state, Figure 6 In the region 320, the screw 900 does not rotate and a high torque g is present. In other words, the spindle speed is equal to zero in this state. Figure 6 In the region 310, the torque g decreases rapidly, which in turn causes a rapid increase in the spindle speed and the motor speed f. Due to this rapid increase in the motor speed f caused by the decrease in torque g from the moment the screw 900 is loosened from the fastening carrier 902, it is usually difficult for the user to pick up the loosened screw 900 or nut and prevent it from falling.

[0178] The method according to the invention can be used to prevent the threaded element, which can be a screw 900 or a nut, from being screwed quickly and thus falling off after being loosened from the fastening carrier 902. Figure 7 In terms of the axes and graphs shown, Figure 7 Basically corresponds to Figure 6 , and corresponding reference numerals represent corresponding features.

[0179] In one specific embodiment, the routine in step S5 includes stopping the handheld power tool 100 immediately after determining that the handheld power tool 100 has recognized a work progress to be recognized, which in the example is the operating mode “no impact”. Figure 7 The motor speed is shown by the branch line f' of the graph line f in the region 310, which drops sharply. Stopp The time after which the appliance stops can be defined by the user. In the figure, this is shown by the branch line f" of the graph line f of the motor speed. A person skilled in the art recognizes that Figure 6 As shown in FIG. 1 , the motor speed first increases rapidly after the transition from region 320 (operating state “bumping”) to region 310 (operating state “no bumping”) and then decreases rapidly in the time period T Stopp After that it dropped sharply.

[0180] In a properly selected time period T Stopp In the case of a screw 900 or a nut, the motor speed is reduced to "zero" just when the screw 900 or the nut is still in the threaded portion. In this case, the user can remove the screw 900 or the nut by turning a few turns or alternatively leave it in the threaded portion to, for example, open the clamp.

[0181] According to the following Figure 8 Another embodiment of the present invention is described. In this case, after the transition from region 320 (operating state "impact") to region 310 (operating state "no impact"), the motor speed is reduced. The magnitude or size of this reduction is indicated in the figure as Δ D The reduction is indicated as a measure between the average value f" of the motor speed in the region 320 and the reduced motor speed f'. In certain embodiments, this reduction can be set by the user, in particular by specifying a target value for the speed of the handheld power tool 100, which is Figure 8 Located at the level of branch line f'.

[0182] By reducing the motor speed and thus also the spindle speed, the user has more time to react when the head of the screw 900 comes loose from the screw contact surface. Once the user thinks that the screw head or nut has been screwed in enough, he can stop the handheld power tool 100 with the help of a switch.

[0183] Combined with Figure 7Compared to the described embodiment, in which the hand-held power tool 100 is stopped immediately or with a delay after the transition from region 320 (operating state “impact”) to region 310 (operating state “no impact”), the speed reduction has the advantage that it is largely independent of the application situation, since it is the user who ultimately determines when the hand-held power tool is to be shut down after the speed reduction. This can be advantageous in the case of long threaded rods, for example. There are application situations in this context in which a more or less longer unscrewing process must be carried out after the threaded rod has become loose and the impact mechanism has come to a stop therewith. In these cases, it is not appropriate to shut down the hand-held power tool 100 after the impact mechanism has stopped,

[0184] It should be mentioned that in some embodiments of the invention it is provided that the parameters of the first routine used in method step S5 can be defined by a learning process as described above based on exemplary applications and / or screw characteristic curves, such as the course and amplitude of the speed reduction or increase.

[0185] In some embodiments of the present invention, the progress of the work is output to a user of the handheld power tool using an output device of the handheld power tool.

[0186] Some technical connections and implementation methods for executing method steps S1 - S4 are explained below.

[0187] In practical applications, it can be provided that method steps S2 and S3 are repeatedly performed during operation of the handheld power tool 100 in order to monitor the progress of the work of the application being performed. For this purpose, in method step S2, the ascertained signal of the operating variable 200 can be segmented so that method steps S2 and S3 are performed on signal segments that preferably have a constant, determined length.

[0188] For this purpose, the signal of the operating variable 200 can be stored as a sequence of measured values ​​in a memory, preferably a ring-shaped memory. In this embodiment, the handheld power tool 100 comprises a memory, preferably a ring-shaped memory.

[0189] As already mentioned in conjunction with FIG. 2 , in a preferred embodiment of the invention, in method step S2, the signal of operating variable 200 is ascertained as a time profile of a measured value of the operating variable or as a measured value of a variable of the operating variable associated with the time profile with respect to electric motor 180. The measured values ​​can be discrete, approximately continuous or continuous.

[0190] The implementation scheme provides that in method step S2, the signal of the operating parameter 200 is recorded as the time curve of the measured value of the operating parameter and in method step S2a following method step S2, the time curve of the measured value of the operating parameter is converted into the curve of a parameter of the measured value of the operating parameter with respect to the electric motor 180 that is associated with the time curve, such as the rotation angle of the tool receiving part 140, the motor rotation angle, acceleration, jerk, in particular higher-order jerk, power or energy.

[0191] The advantages of this embodiment are described below with reference to FIG. 9. Similar to FIG. 2, Figure 9a The signal f(x) of the operating variable 200 is shown with respect to the abscissa x, where the abscissa is currently the time t. As in FIG2 , the operating variable may be the motor speed or a variable associated with the motor speed.

[0192] The image contains two signal curves of the operating variable 200, which can each be assigned to a work progress, for example, to a rotary impact screwing mode in the case of a rotary impact screwdriver. In both cases, the signal includes a wavelength of an oscillation curve that is ideally assumed to be sinusoidal, wherein the signal with a shorter wavelength T1 has a curve with a higher impact frequency, and the signal with a longer wavelength T2 has a curve with a lower impact frequency.

[0193] Both signals can be generated with the same handheld power tool 100 at different motor speeds and depend in particular on the rotational speed requested by the user via an operating switch of the handheld power tool 100 .

[0194] If, for example, the parameter “wavelength” is used to define a state-typical model waveform 240, then in the present case at least two different wavelengths T1 and T2 must be stored as possible parts of the state-typical model waveform so that a comparison of the signal of the operating variable 200 with the state-typical model waveform 240 leads to “identical” results in both cases. Since the motor speed generally changes over time and to a large extent, this has the consequence that the wavelength to be sought also changes and therefore the method for identifying the impulse frequency must be adapted accordingly.

[0195] With a large number of possible wavelengths, the complexity of such methods and programming increases correspondingly rapidly.

[0196] Thus, in a preferred embodiment, the time values ​​of the abscissa are converted into values ​​associated with the time values, such as acceleration values, higher-order jerk values, power values, energy values, frequency values, values ​​of the rotation angle of the tool receiving part 140 or values ​​of the rotation angle of the electric motor 180. This is possible because the fixed transmission ratio of the electric motor 180 to the impact mechanism and to the tool receiving part 140 results in a direct, known relationship between the motor speed and the impact frequency. By normalization, a periodically constant oscillating signal is achieved that is independent of the motor speed, which is Figure 3 b shows two signals resulting from the transformation of the signals belonging to T1 and T2 , wherein the two signals now have the same wavelength P1 = P2 .

[0197] Accordingly, in an embodiment of the present invention, a sample waveform 240 which is typical in terms of the state and which is applicable to all rotational speeds is determined by a single parameter of the wavelength with respect to a time-related variable, such as the rotation angle of the tool receiving part 140, the motor rotation angle, acceleration, jerk, in particular high-order jerk, power or energy.

[0198] In a preferred embodiment, in method step S3, the comparison of the signal of the operating parameter 200 is performed by a comparison method, wherein the comparison method includes at least one frequency-based comparison method and / or a comparative comparison method. The comparison method compares the signal of the operating parameter 200 with a sample waveform 240 that is typical in terms of the state: whether at least a consistency threshold is met. The comparison method compares the measured signal of the operating parameter 200 with a consistency threshold. The frequency-based comparison method includes at least a bandpass filter and / or a frequency analysis. The comparative comparison method includes at least a parameter evaluation and / or a cross-correlation. The frequency-based comparison method and the comparative comparison method are described in detail below.

[0199] In an embodiment with the aid of a bandpass filter, the input signal, which is likewise transformed into a time-dependent variable as described, is filtered through one or more passbands, the passbands of which correspond to one or more state-typical model waveforms. The passbands are obtained from the state-typical model waveform 240. It is also conceivable that the passbands correspond to a frequency determined in conjunction with the state-typical model waveform 240. When the work progress to be identified is reached, the amplitude of the frequency exceeds a previously determined limit value, if the amplitude of the frequency exceeds the limit value, then the comparison in method step S3 leads to the conclusion that the signal of the operating variable 200 is identical to the state-typical model waveform 240, so that the work progress to be identified has been reached. In this embodiment, the determination of the amplitude limit value can be understood as the determination of a consistency evaluation of the state-typical model waveform 240 and the signal of the operating variable 200, based on which it is determined in method step S4 whether there is a work progress to be identified.

[0200] The following embodiment is to be explained with reference to FIG. 10 , in which a frequency analysis is used as a frequency-based comparison method. In this case, a signal of the operating variable 200 , as shown in FIG. 10 ( a ) and corresponding, for example, to the time course of the rotational speed of the electric motor 180 , is transformed from the time domain into the frequency domain with corresponding weighting of the frequencies based on the frequency analysis, for example, based on a Fast Fourier Transformation (FFT). Here, the term “time domain” is to be understood as both “the time course of the operating variable” and “the course of the operating variable as a time-dependent variable” according to the above embodiment.

[0201] This form of frequency analysis is well known as a mathematical tool for signal analysis in many technical fields and is used in particular to approximate the measured signal as a series expansion of weighted periodic harmonic functions of different wavelengths. Figure 10(b) and 10(c) By way of example, the weighting factors κ1(x) and κ2(x) of the function curves 203 and 204 as a function of time indicate whether and to what extent corresponding frequencies or frequency bands exist in the signal under investigation, i.e., the course of the operating variable 200, which are not plotted here for the sake of clarity.

[0202] That is, in the method according to the invention, it is possible to determine by means of frequency analysis whether a frequency associated with a state-typical model waveform 240 is present in the signal of the operating variable 200 and at what amplitude it is present. In addition, however, it is also possible to define a frequency whose absence is a measure of the presence of the work progress to be detected. As mentioned in connection with the bandpass filter, an amplitude limit value can be determined, which is a measure of the degree of correspondence between the signal of the operating variable 200 and the state-typical model waveform 240.

[0203] In the example of FIG. 10( b ), in the signal of the operating variable 200 , for example at time t2 (point SP2), the amplitude κ1(x) of the first frequency which should not normally be present in the first sample waveform 240 which is typical for the state falls below the corresponding boundary value 203(a), which is a necessary but not sufficient criterion for the presence of the work progress to be identified in this example. In the signal of the operating variable 200 , at time t3 (point SP3), the amplitude κ2(x) of the second frequency which can normally be found in the second sample waveform 240 which is typical for the state exceeds the corresponding boundary value 204(a). In a corresponding embodiment of the present invention, the simultaneous presence of the amplitude functions κ1(x), κ2(x) falling below or exceeding the boundary values ​​203(a), 204(a) respectively is a decisive criterion for the evaluation of the consistency of the signal of the operating variable 200 with the sample waveform 240 which is typical for the state. Accordingly, in this case, it is determined in method step S4 that the work progress to be identified has been reached.

[0204] In alternative embodiments of the present invention, only one of these criteria or a combination of one or two of these criteria with other criteria (eg, achieving a desired rotational speed of electric motor 180 ) is used.

[0205] In one embodiment, a comparative comparison method is used, in which the signal of the operating variable 200 is compared with a state-typical model waveform 240 to find out whether the measured signal of the operating variable 200 is at least 50% consistent with the state-typical model waveform 240 and thus whether a predetermined threshold value is reached. It is also conceivable to compare the signal of the operating variable 200 with the state-typical model waveform 240 to determine the consistency of the two signals with each other.

[0206] In some embodiments of the method according to the invention, parameter evaluation is used as a comparative comparison method, in which the measured signal of the operating variable 200 is compared with a state-typical model waveform 240, wherein the parameters evaluated for the state-typical model waveform 240 are identified. The degree of consistency of the measured signal of the operating variable 200 and the state-typical model waveform 240 can be determined with the aid of the evaluation parameters: whether the work progress to be identified has been achieved. The parameter evaluation is based on an adjustment calculation (Ausgleichungsrechnung), which is a mathematical optimization method known to those skilled in the art. This mathematical optimization method makes it possible to adapt the state-typical model waveform 240 to a series of measurement data of the signal of the operating variable 200 with the aid of the evaluation parameters. Based on the degree of consistency of the state-typical model waveform 240 parameterized with the aid of the evaluation parameters and the limit values, it can be determined whether the work progress has been achieved.

[0207] By means of an adjustment calculation using a comparative method of parameter estimation, it is also possible to determine the degree of correspondence between the estimation parameters of the state-typical template waveform 240 and the measured signal of the operating variable 200 .

[0208] In an embodiment of the method according to the invention, in method step S3, a cross-correlation method is used as a comparative comparison method. Like the mathematical methods mentioned above, the cross-correlation method is also sufficiently known to the person skilled in the art. In the cross-correlation method, a sample waveform 240 which is typical for the state is correlated with the measured signal of the operating variable 200.

[0209] Analogously to the parameter estimation method described above, the result of the cross-correlation is a signal sequence having a signal length which is the sum of the length of the signal of the operating variable 200 and the state-typical model waveform 240, which indicates the similarity of the time-shifted input signals. The maximum of the output sequence represents the time of maximum agreement of the two signals (i.e. the signal of the operating variable 200 and the state-typical model waveform 240) and is thus also a measure of the correlation itself, which in this embodiment is used in method step S4 as a criterion for reaching the work progress to be identified. In the execution of the method according to the invention, a significant difference from parameter estimation is that any state-typical model waveform can be used for the cross-correlation, whereas in parameter estimation the state-typical model waveform 240 must be representable by a parameterizable mathematical function.

[0210] 11 shows a measured signal of an operating variable 200 for the case in which a bandpass filter is used as a frequency-based comparison method. The abscissa x is the time t or a variable that is correlated with time. Fig.11aMeasured signals of operating variables, input signals of a bandpass filter, are shown, wherein in a first range 310 the handheld power tool 100 is operated in a screw-driving operating mode. In a second range 320 the handheld power tool 100 is operated in a rotary impact operating mode. Fig.11b The output signal is presented after the input signal has been pass-band filtered.

[0211] FIG. 12 shows a measured signal of an operating variable 200 for the case where frequency analysis is used as a frequency-based comparison method. Fig.12a A and b show a first region 310, in which the handheld power tool 100 is operated in a screw-driving mode. Fig.12a The horizontal axis x is time t or a parameter related to time. Figure 12b In FIG. 1 , the signal of the operating variable 200 is shown in a transformed form, wherein the signal can be transformed from the time domain into the frequency domain by means of a fast Fourier transformation, for example. Figure 12b For example, the frequency f is plotted on the abscissa x' of , so that the amplitude of the signal of the operating variable 200 is shown. Fig.12c d show a second region 320 in which the handheld power tool 100 is in a rotary impact operation. Fig.12c The measured time signal of operating variable 200 in the rotary impact operation is shown. Fig.12d A transformed signal of operating variable 200 is shown, wherein the signal of operating variable 200 is plotted over frequency f as abscissa x′. Fig.12d Characteristic amplitudes of the rotary impact operation are shown.

[0212] Fig.13a A typical case of a comparison between the signal of the operating variable 200 and the state-typical model waveform 240 by means of a comparative comparison method of parameter evaluation in the first region 310 described in FIG2 is shown. While the state-typical model waveform 240 has an essentially trigonometric course, the signal of the operating variable 200 has a course that differs greatly from this. Independent of the choice of the comparison method described above, in this case the comparison between the state-typical model waveform 240 and the signal of the operating variable 200 carried out in method step S3 yields the result that the degree of agreement between the two signals is so low that no work progress to be identified in method step S4 can be determined.

[0213] and Fig.13b 2 shows the situation where there is a work progress to be identified, so that the typical template waveform 240 and the signal of the operating variable 200 have a high degree of consistency in terms of the state, although deviations can be determined at individual measuring points. It can be determined by a comparative comparison method of parameter evaluation whether the work progress to be identified has been achieved.

[0214] FIG. 14 shows a typical sample waveform 240 for the state (see FIG. Fig.14b and 14e) and the measured signal of the operating variable 200 (see Fig.14a and 14d), for the following cases: using cross-correlation as a contrastive comparison method. Fig.14a -f plots time or time-related parameters on 14x. Fig.14a -c shows the first region 310 corresponding to the screwing operation. Fig.14d -f shows a third area 324 corresponding to the work progress to be identified. As described above, the measured signal ( Fig.14a and Fig.14d ) and the typical sample waveform in terms of state ( Fig.14b and 14e). Fig.14c The corresponding correlation results are shown in and 14f. Fig.14c The correlation result during the first region 310 is shown in FIG. , where it can be seen that there is a small coincidence of the two signals. Fig.14c In the example of , it is determined in method step S4 that the work progress to be identified has not been reached. Fig.14f The correlation during the third region 324 is shown in FIG. Fig.14f As can be seen in FIG. 1 , there is a high degree of consistency, so that in method step S4 it is determined that the work progress to be identified has been reached.

[0215] The invention is not limited to the exemplary embodiments described and shown, but rather also encompasses all developments conceivable by a person skilled in the art within the scope of the inventive concept defined by the claims.

[0216] Other embodiments are conceivable that may include further variations and combinations of features besides those described and shown.

Claims

1. A method for operating a handheld power tool (100), the handheld power tool (100) comprising an electric motor (180), the method comprising the following method steps: S1 providing comparison information, S1 comprising the following steps: S1a provides at least one template waveform (240), wherein the template waveform (240) can be assigned to the progress of a work process of the hand-held power tool (100); S1b provides a consistency threshold; S2 obtains a signal of an operating variable (200) of the electric motor (180); S3 compares the signal of the operating variable (200) with the template waveform (240) during the work process of the hand-held power tool (100) and obtains a consistency evaluation from the comparison, wherein the consistency evaluation is performed at least partially based on the consistency threshold; S4 identifies the progress of the work process at least partially based on the consistency evaluation obtained in method step S3; S5 During a working process of the handheld machine tool (100), a first routine of the handheld machine tool (100) is executed at least partially based on the working progress identified in method step S4, wherein the first routine includes switching off an electric motor (180) of the handheld machine tool (100), changing the rotational speed of the electric motor (180) and / or triggering feedback to a user of the handheld machine tool (100); wherein the provision of the comparative information is at least partially based on a learning process, wherein the learning process includes executing or reading in a learning process of the handheld machine tool (100). At least one exemplary application, wherein the at least one exemplary application includes reaching a certain work progress of the handheld power tool (100), wherein the template waveform (240) is provided at least partially based on the learning process, and the learning process includes the following method steps: A1 determining a signal of an operating variable (200') of the electric motor (180) based on the exemplary application; A2 determining a template waveform (240') assigned to the exemplary application based on the signal of the operating variable (200') during reaching the certain work progress; A2' determining a template waveform (240') assigned to the exemplary application based on the signal of the operating variable (200') present at the time when the certain work progress is reached.

2. The method according to claim 1, characterized in that The learning process includes executing or reading in at least two exemplary applications, and the learning process includes ascertaining the model waveform (240) from two or more model waveforms (240') assigned to the at least two exemplary applications.

3. The method according to claim 1, characterized in that The consistency threshold is provided at least partially based on the learning process, and the learning process includes the following method steps: B1 providing at least one template waveform (240"), wherein the template waveform (240") can be assigned to a working progress of the handheld power tool (100); B2 determining a signal of an operating variable (200') of the electric motor (180); and B3 comparing the signal of the operating variable (200') with the template waveform (240") at a time when the speed of the electric motor (180) is reduced, and determining a consistency threshold assigned to the exemplary application.

4. The method according to claim 3, wherein: In step B1 , the at least one template waveform is provided according to the method according to claim 1 or 2 .

5. The method according to claim 3, characterized in that: The learning process includes executing or reading in at least two exemplary applications and the learning process includes averaging the consistency threshold value from two or more consistency threshold values ​​assigned to the at least two exemplary applications.

6. The method according to claim 1 or 2, characterized in that: Reading in at least one exemplary application includes reading in an exemplary signal of an operating variable of the electric motor by the handheld power tool (100).

7. The method according to claim 1 or 2, characterized in that: The first routine includes stopping the electric motor (180) taking into account defined and / or predefinable parameters.

8. The method according to claim 1 or 2, characterized in that: The first routine includes varying the speed of the electric motor (180).

9. The method according to claim 8, characterized in that The change in the rotational speed of the electric motor (180) is performed multiple times and / or dynamically, wherein the change in the rotational speed is determined at least partially according to the learning process based on the exemplary application.

10. The method according to claim 1 or 2, characterized in that: The operating variable is the rotational speed of the electric motor (180) or an operating variable that is correlated with the rotational speed.

11. The method according to claim 1 or 2, characterized in that: In method step S2, the signal of the operating variable (200) is recorded as a time profile of a measured value of the operating variable or as a measured value of the operating variable as a variable of the electric motor (180) that is correlated with the time profile.

12. The method according to claim 1 or 2, characterized in that: In method step S2, the signal of the operating variable (200) is recorded as a time curve of a measured value of the operating variable, and, in method step S2a following method step S2, the time curve of the measured value of the operating variable is converted into a curve of the measured value of the operating variable as a variable of the electric motor (180) associated with the time curve.

13. The method according to claim 1 or 2, characterized in that: The handheld power tool (100) is an impact driver and the work process is an impact operation.

14. The method according to claim 3, characterized in that The learning process comprises the following method step: B3, at the time when the handheld power tool (100) is stopped by a user, the signal of the operating variable (200') is compared with the template waveform (240") and a consistency threshold value associated with the exemplary application is determined.

15. The method according to claim 7, characterized in that The first routine includes stopping the electric motor (180) taking into account parameters that are defined and / or can be predefined by a user of the handheld power tool (100).

16. The method according to claim 8, characterized in that The first routine includes reducing and / or increasing the rotational speed of the electric motor (180).

17. The method according to claim 9, characterized in that The change in the rotational speed of the electric motor (180) occurs in a temporally stepped manner and / or along a characteristic curve of the rotational speed change and / or as a function of the progress of work of the handheld power tool (100), wherein the change in rotational speed is determined at least partially as a function of the learning process based on the exemplary application.

18. The method according to claim 13, characterized in that The handheld power tool (100) is a rotary impact screwdriver.

19. The method according to claim 13, characterized in that The working progress described is a rotary impact operation.

20. A handheld power tool (100) comprising an electric motor (180), a measured value recorder of operating variables of the electric motor (180), and a control unit (370), characterized in that: The control unit (370) is designed to carry out the method according to any one of claims 1 to 19.

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