Drop detection of power tools

Abstract

A fall detection module for a power tool, the fall detection module comprising: an accelerometer arranged to detect an acceleration of the power tool; a power controller configured to control an operating state of the power tool; and a processor configured to use the detected acceleration of the power tool to determine an impact condition following the power tool after a free-fall condition of the power tool, and instruct the power controller to stop operation of the power tool in response to determining that the impact condition is followed by the free-fall condition.

Description

Technical Field

[0001] This disclosure relates to the detection of a falling power tool, and more particularly to a mechanism for detecting the fall of a power tool and thereby stopping operation. Background Art

[0002] Many handheld power tools are operated using a simple push-button trigger, i.e., as long as the trigger button is pressed, the tool is powered. The user must hold the trigger to keep the tool running. Some tools (e.g., many angle grinders and other tools) have a "lock" function, whereby the trigger is locked in the working position and the tool continues to run regardless of whether the user applies pressure to the trigger. This can reduce the user's burden and allow the user to change hands, work at different angles, or even put down the tool.

[0003] However, if the user drops the tool while the lock function is engaged, the lock function can be dangerous because the tool will continue to run while falling and may bounce in an uncontrolled manner.

[0004] The aim of this disclosure is to solve or at least partially improve some of the above limitations of the current methods. Summary of the Invention

[0005] The features and advantages of this disclosure will be set forth in the following description, and in part will be apparent from the description, or may be learned by practicing the principles disclosed herein. The features and advantages of this disclosure may be realized and obtained by the instruments and combinations particularly pointed out in the appended claims.

[0006] According to a first aspect of this disclosure, there is provided a fall detection module for a power tool, the fall detection module comprising: an accelerometer arranged to detect the acceleration of the power tool; a power controller configured to control the operating state of the power tool; and a processor configured to use the detected acceleration of the power tool to determine the free fall state of the power tool followed by the impact state of the power tool, and to instruct the power controller to stop the operation of the power tool in response to determining that the free fall state is followed by the impact state.

[0007] Determining the free fall state may include determining that the acceleration of the detected power tool is substantially zero over a minimum time period.

[0008] Determining the impact state may include determining that the acceleration of the detected power tool rises above a predefined threshold acceleration.

[0009] Determining an impact state can include determining a return to a free-fall state within a predetermined time after the detected acceleration of the power tool rises above a predefined threshold acceleration.

[0010] The processor can be configured to instruct the power controller to actively decelerate the motor of the power tool in response to determining that an impact state follows a free-fall state.

[0011] The processor can be configured to instruct the power controller to apply a preselected braking curve to actively decelerate the motor of the power tool.

[0012] The fall detection module can include an active braking mechanism.

[0013] The processor can be configured to activate the active braking mechanism in response to determining that an impact state follows a free-fall state.

[0014] According to a second aspect of the present disclosure, there is provided a power tool including the fall detection module of the first aspect.

[0015] According to a third aspect of the present disclosure, there is provided a computer-implemented method for controlling an operating state of a power tool, the method including: detecting an acceleration of the power tool; using the detected acceleration of the power tool to determine a free-fall state of the power tool followed by an impact state of the power tool; and stopping an operation of the power tool in response to determining that an impact state follows a free-fall state.

[0016] Determining the free-fall state can include determining that the detected acceleration of the power tool is substantially zero within a minimum time period.

[0017] Determining the impact state can include determining that the detected acceleration of the power tool rises above a predefined threshold acceleration.

[0018] Determining the impact state can further include determining a return to a free-fall state within a predetermined time after the detected acceleration of the power tool rises above a predefined threshold acceleration.

[0019] The method can include actively decelerating the motor of the power tool in response to determining that an impact state follows a free-fall state.

[0020] The method can include applying a preselected braking curve to actively decelerate the motor of the power tool.

[0021] The method can include activating the active braking mechanism in response to determining that an impact state follows a free-fall state.

[0022] According to a first aspect of the present disclosure, there is provided a computer-readable medium configured to store instructions that, when executed by a processor, cause the processor to perform the method of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To describe the manner in which the above and other advantages and features of the present disclosure can be obtained, the principles briefly described above will be described in more detail by reference to specific embodiments of the present disclosure shown in the accompanying drawings. It should be understood that these drawings depict only exemplary embodiments of the present disclosure and are not to be considered limiting of the scope of the present disclosure, and the principles herein are described and explained more specifically and in detail by using the drawings.

[0024] The preferred embodiments of the present disclosure will be further explained in detail below by way of examples and with reference to the accompanying drawings, in which: -

[0025] Figure 1 A schematic diagram of a power tool having a fall detection module according to an embodiment is shown.

[0026] Figure 2 An exemplary acceleration chart of the power tool is shown.

[0027] Figure 3 An exemplary acceleration chart of the power tool is shown.

[0028] Figure 4 Accelerometer test data for an implementation of the fall detection module is shown.

[0029] Figure 5 A method of controlling the operating state of a power tool according to an embodiment is shown. DETAILED DESCRIPTION

[0030] Various different embodiments of the present disclosure are discussed in detail below. Although specific implementations are discussed, it should be understood that this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations can be used without departing from the scope of the present disclosure.

[0031] Referring to the accompanying drawings, in Figure 1 a power tool 1 including a fall detection module 10 according to an embodiment is shown. The fall detection module 10 includes an accelerometer 100, a processor 200, and a power controller 300.

[0032] The accelerometer 100 is arranged to detect the acceleration of the power tool 1. In some examples, the accelerometer 100 can be a 3-axis accelerometer 100 configured to sense acceleration along three mutually perpendicular axes.

[0033] The processor 200 is configured to use the detected acceleration of the power tool 1 to determine the free fall state of the power tool 1. A stationary object is subject to gravity in the downward direction, which is equivalent to an upward acceleration of approximately 9.81 m / s² (or "1g"). Thus, when the power tool 1 is stationary, the accelerometer 100 can detect an acceleration that is substantially equal to 1g. During normal operation of the power tool 1, such as when the user is moving the power tool, the acceleration of the tool can remain close to 1g.

[0034] However, if the power tool 1 is allowed to fall, the acceleration may quickly tend towards zero. Thus, when the power tool 1 is falling, the accelerometer 100 can detect an acceleration that is substantially equal to zero. In some examples, when the detected acceleration is substantially zero, it can be determined that the power tool 1 is in a free fall state.

[0035] In some examples, the processor 200 can be configured to use the magnitude of the detected acceleration to determine the free fall state. For example, the magnitude can be the average or the modulus of the accelerations along three axes.

[0036] The processor 200 is further configured to use the detected acceleration of the power tool 1 to determine a shock state following the free fall state of the power tool 1. If the falling power tool 1 hits the ground, the accelerometer 100 can detect an acceleration that rapidly increases from zero when the tool stops and / or bounces off the ground. In some examples, when the detected acceleration rapidly increases from zero, it can be determined that the power tool 1 is in a shock state.

[0037] The processor 200 is further configured to instruct the power controller 300 to stop the operation of the power tool 1 in response to determining that a shock state follows the free fall state.

[0038] The power controller 300 is configured to control the operating state of the power tool 1. The power controller 300 can be configured to stop the operation of the power tool 1 in response to an instruction from the processor 200. In some examples, the power tool 1 can include a motor 20, and the power controller 300 can control the operating state of the motor 20. For example, the power controller 300 can be configured to stop the motor 20 from running. In some examples, the power controller 300 can be configured to override the trigger or locking mechanism of the power tool 1 to stop the operation of the power tool 1. Alternatively or additionally, the power controller 300 can be configured to interrupt the power supply to the power tool 1 or specifically to the motor 20.

[0039] In this way, the operating safety of the power tool 1 can be significantly improved. By stopping the operation of the power tool 1 in response to a fall, the fall detection module 10 can reduce the likelihood of damage or injury caused by the falling of the operating power tool 1 or its bouncing in an uncontrolled manner.

[0040] In addition, by being triggered using a free fall state followed by an impact state, the fall detection module 10 can prevent the power tool 1 from accidentally stopping operation due to a misjudgment during normal operation, which could occur if only the free fall state were used for triggering. For example, a user may cause the power tool 1 to briefly enter a free fall state when squatting or picking up the tool, so using the impact state for triggering can prevent the accidental stoppage of the power tool 1.

[0041] Figure 2 An exemplary acceleration graph of the power tool 1 is shown. The graph shows the normal state, free fall state, and ground impact state (or "impact state") of the power tool 1.

[0042] As described above, in the normal state, the total acceleration of the power tool 1 can tend to 1g because the tool is in normal use or stationary. Additionally, when the power tool 1 is in a free fall state, the total acceleration of the power tool 1 can tend to zero.

[0043] In some examples, determining the free fall state can include determining that the detected acceleration of the power tool 1 is substantially zero over a minimum time period.

[0044] Since the relationship between the free fall height and time can be calculated as H = 1 / 2gT 2 , in some examples, a safety height H S can be set, and the corresponding free fall time T S can be calculated. The free fall time T S can be set as the minimum time period such that if the actual free fall time T A > T S , then the actual free fall height H A > H S . Alternatively, in some examples, once the detected acceleration is substantially zero, the free fall state can be recognized.

[0045] As used herein, the term "substantially zero" means being at or near a zero value, as the acceleration may not reach an exact zero value due to air resistance or other physical effects. The tolerance required for a zero reading of the accelerometer 100 can be established through testing and / or calibration and can be, for example, a value less than 0.1ms -2 or 0.5ms -2 .

[0046] In some embodiments, determining an impact state may include determining that the detected acceleration of the power tool 1 has risen above a predefined threshold acceleration. In some examples, when the power tool 1 contacts the ground and changes from a free-fall state to an impact state, the total acceleration of the tool may oscillate from zero. As shown, the acceleration may oscillate successively between hitting the ground and rebounding and another free-fall state, and finally stabilize and tend to 1g.

[0047] In some examples, the predefined threshold acceleration may be established through testing and / or calibration. For example, the predefined threshold acceleration may be 0.5g or 1g.

[0048] In some examples, the predefined threshold acceleration is based only on the magnitude of the acceleration. Alternatively, in some examples, the predefined acceleration threshold may be based on the direction using a 3-axis sensor. For example, if the acceleration direction changes significantly, which may indicate a dangerous rebound in another direction, the predefined acceleration threshold may be reduced.

[0049] Figure 3 An exemplary acceleration chart of the power tool 1 is shown, showing only the impact state.

[0050] In some embodiments, determining an impact state may further include determining a return to a free-fall state within a predetermined time after the detected acceleration of the power tool 1 has risen above the predefined threshold acceleration.

[0051] At point (1), it is detected that the acceleration has increased from a very low value to a value greater than the predefined threshold acceleration, which may indicate that the tool has bounced off the ground. Subsequently, at point (2), it is detected that the acceleration value after bouncing off the ground has fallen back towards zero, which may indicate another free-fall state after the tool has bounced off the ground. In some examples, when (1) is triggered, (2) must be triggered within a predetermined time to trigger the impact state, otherwise it may be regarded as normal use.

[0052] Figure 4 Accelerometer 100 test data for an implementation of the fall detection module 10 is shown. The first graph shows the acceleration of the power tool 1 after dropping from 10 cm. The second graph shows the acceleration of the power tool 1 after dropping from 20 cm. The free-fall state and the impact state are highlighted on each graph. It should be noted that when the power tool 1 drops from a higher point, the free-fall state is longer, and the acceleration in the impact state when hitting the ground oscillates more sharply. However, it should be noted that in both cases, the characteristics of the free-fall state followed by the impact state can be detected in order to correctly stop the operation of the power tool 1.

[0053] In some embodiments, the processor 200 may be configured to instruct the power controller 300 to actively decelerate the motor 20 of the power tool 1 in response to determining that a free fall state is followed by an impact state. For example, in the case where the motor 20 is a brushless motor 20, the power controller 300 may be configured to transmit a signal that is not synchronized with the rotation of the motor 20 and cause the magnetic elements of the motor 20 to act contrary to the movement of the motor 20, thereby decelerating the motor 20. In some examples, the signal transmitted to the motor 20 may be selected from a plurality of signals corresponding to different braking curves (e.g., to cause faster or slower braking of the power tool 1).

[0054] In some embodiments, the processor 200 is configured to instruct the power controller 300 to apply a preselected braking curve to actively decelerate the motor 20 of the power tool 1. For example, in the case where the power tool 1 is configured to employ a certain braking curve during normal use (e.g., when releasing the trigger of the power tool 1), the power controller 300 may be configured to select a faster curve in response to determining that a free fall state is followed by an impact state. In this way, the power tool 1 can brake faster in an emergency. In some examples, a specific braking curve may also be selected based on a 3-axis sensor. For example, if a dangerous lateral rebound is detected, a faster braking curve may be selected.

[0055] In some embodiments, the power tool 1 may include an active braking mechanism. In some embodiments, the processor 200 may be configured to activate the active braking mechanism in response to determining that a free fall state is followed by an impact state. In some examples, the active braking mechanism may include a friction member, which for example includes one or more brake pads that are arranged to contact a moving part of the power tool 1 (such as the disc of a grinder). In some examples, the active braking mechanism may include a blocking member, such as an element that physically obstructs the moving part of the power tool 1. In some examples, the active braking mechanism may be designed to be disposable, for example due to damage to the power tool 1 or the active braking mechanism itself, or may be used multiple times.

[0056] In some examples, the accelerometer 100 may be placed as far away from the motor 20 as possible. In this way, the influence of the vibration of the power tool 1 itself on the accelerometer 100 can be reduced. In some examples, the accelerometer 100 may be placed at the base of the power tool 1, such as at the connection of the power tool 1 to the battery pack.

[0057] In some embodiments, the fall detection module 10 may be provided as part of the power tool 1. Alternatively, in some embodiments, the fall detection module 10 may be provided separately.

[0058] Individual modules can be connected to the control logic board of the tool, for example, via available bus connections. Alternatively, the module can be configured to dock with a battery pack or battery connection to interrupt the power supply in the event of a detected fall.

[0059] In some examples, the accelerometer 100 can operate in a range such as ±2g, ±4g, ±8g, or ±16g. In some examples, this range can be user-selectable to configure the fall detection module 10. In some examples, the resolution of the accelerometer 100 can be 14 bits, or can be any suitable value selected, for example, in the range from 8 bits to 32 bits. In some examples, the data output rate of the accelerometer 100 can be in the range from 1 Hz to 1000 Hz.

[0060] Figure 5 is a flowchart showing a method of controlling the operating state of a power tool. The method begins at step S01.

[0061] In step S02, the acceleration of the power tool is detected.

[0062] In step S03, the detected acceleration of the power tool is used to determine the free-fall state of the power tool.

[0063] In step S04, the detected acceleration of the power tool is used to determine the impact state of the power tool.

[0064] In step S05, the operation of the power tool is stopped in response to determining that the free-fall state is followed by an impact state.

[0065] The method ends at step S06.

[0066] The above embodiments are described only by way of example. Many variations are possible without departing from the scope of the present disclosure as defined in the appended claims.

[0067] For clarity of explanation, in some cases, the present technology may be presented as including separate functional blocks, which include functional blocks containing devices, device components, steps or routines in a method embodied in software or a combination of hardware and software.

[0068] The methods according to the above examples can be implemented using computer-executable instructions stored in a computer-readable medium or otherwise obtainable from a computer-readable medium. Such instructions can include, for example, instructions and data that cause or otherwise configure a general-purpose computer, a special-purpose computer, or a special-purpose processing device to perform a certain function or group of functions. Portions of the computer resources used can be accessed via a network. The computer-executable instructions can be, for example, binary instructions, intermediate format instructions (such as, assembly language), firmware, or source code. Examples of computer-readable media that can be used to store instructions, information used, and / or information generated during the methods according to the described examples include magnetic or optical disks, flash memory, universal serial bus (USB) devices provided with non-volatile memory, networked storage devices, and the like.

[0069] Apparatuses for implementing the methods according to these disclosures can include hardware, firmware, and / or software, and can take any of a variety of form factors. Typical examples of such form factors include laptop computers, smart phones, small form factor personal computers, personal digital assistants, and the like. The functions described herein can also be embodied in peripheral devices or add-on cards. By additional example, such functions can also be implemented on a circuit board between different chips or different processes executed in a single device.

[0070] Instructions, the medium for transmitting such instructions, the computing resources for executing these instructions, and other structures for supporting these computing resources are means for providing the functions described in this disclosure.

[0071] Although various examples and other information are used to explain aspects within the scope of the appended claims, in such examples, no limitation of the claims should be implied based on a particular feature or arrangement, because a person of ordinary skill in the art will be able to use these examples to derive a wide variety of implementations. Further, although some subject matter may have been described in language specific to example structural features and / or method steps, it should be understood that the subject matter defined in the appended claims is not necessarily limited to these features or acts described. For example, such functions can be distributed differently or performed in components other than those identified herein. Rather, the described features and steps are disclosed as examples of components of systems and methods within the scope of the appended claims.

Claims

1. A fall detection module for a power tool, the fall detection module comprising: an accelerometer arranged to detect the acceleration of the power tool; a power controller configured to control the operating state of the power tool; and a processor configured to: use the detected acceleration of the power tool to determine the free fall state of the power tool followed by the impact state of the power tool, and in response to determining that the impact state follows the free fall state, instruct the power controller to stop the operation of the power tool.

2. The drop detection module according to claim 1, wherein, Determining the free fall state includes determining that the detected acceleration of the power tool is substantially zero within a minimum time period.

3. The drop detection module according to claim 1 or claim 2, wherein, Determining the impact state includes determining that the detected acceleration of the power tool rises above a predefined threshold acceleration.

4. The drop detection module according to claim 3, wherein, Determining the impact state further includes determining a return to the free fall state within a predetermined time after the detected acceleration of the power tool rises above the predefined threshold acceleration 5. The fall detection module according to any one of the preceding claims, wherein, The processor is further configured to instruct the power controller to actively decelerate the motor of the power tool in response to determining that the impact state follows the free fall state.

6. The fall detection module according to claim 5, wherein The processor is configured to instruct the power controller to apply a preselected braking curve to actively decelerate the motor of the power tool.

7. The drop detection module according to any one of the preceding claims, wherein the drop detection module further comprises an active braking mechanism, where The processor is further configured to activate the active braking mechanism in response to determining that the impact state follows the free fall state.

8. A power tool comprising the fall detection module according to any one of the preceding claims.

9. A computer-implemented method for controlling the operating state of a power tool, the method comprising: detecting the acceleration of the power tool; using the detected acceleration of the power tool to determine the free fall state of the power tool followed by the impact state of the power tool; and in response to determining that the impact state follows the free fall state, stopping the operation of the power tool.

10. The computer-implemented method according to claim 9, wherein, Determining the free fall state includes determining that the detected acceleration of the power tool is substantially zero within a minimum time period.

11. The computer-implemented method according to claim 9 or claim 10, wherein, Determining the impact state includes determining that the detected acceleration of the power tool rises above a predefined threshold acceleration.

12. The computer-implemented method according to claim 11, wherein, Determining the impact state further includes determining a return to the free fall state within a predetermined time after the detected acceleration of the power tool rises above the predefined threshold acceleration.

13. The computer-implemented method according to any one of claims 9 to 12, the method further comprising actively decelerating the motor of the power tool in response to determining that the impact state follows the free fall state.

14. The computer-implemented method according to claim 13, the method comprising applying a preselected braking curve to actively decelerate the motor of the power tool.

15. The computer-implemented method according to any one of claims 9 to 14, the method further comprising activating an active braking mechanism in response to determining that the free fall state is followed by the impact state.

16. A computer-readable medium configured to store instructions that, when executed by a processor, cause the processor to perform the method according to any one of claims 9 to 15.

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