Drop protection system and method for electric tool

Abstract

A drop protection system and method for an electric tool. The drop protection method for an electric tool sequentially comprises: measuring a vertical acceleration of an electric tool, and on the basis of the vertical acceleration, determining whether the electric tool is in a free fall state; when it is determined that the electric tool is in a free fall state, starting timing, and detecting whether an electric motor of the electric tool is in a running state; when it is determined that the electric motor is in a running state, powering off the electric motor of the electric tool; determining whether a drop travel of the electric tool reaches a preset travel threshold value; when it is determined that the drop travel of the electric tool reaches the preset travel threshold value, detecting an angular orientation of the electric tool; determining whether the angular orientation of the electric tool is within a preset dangerous angular orientation range; and when the angular orientation of the electric tool is within the preset dangerous angular orientation range, restarting the electric motor.

Description

Fall protection system and method for power tools Technical Field

[0001] The present application relates to a fall protection system and method for a power tool. Background Art

[0002] For power tools that include motors, especially handheld power tools, accidental drops (or free falls) may occur, whether due to operator negligence or other reasons such as tilting or collision of the supporting structure. On the one hand, when the power tool is dropped, some parts of the power tool (also referred to as consumable parts in this article) may be damaged, such as the power tool's motor, battery, high-precision sensors, housing, etc. On the other hand, if the power tool is dropped during operation (for example, when performing cutting, drilling, or chiseling actions), the high-speed moving motion output components (such as a reciprocating saw blade or chisel or a high-speed rotating drill bit, etc.) may cause damage to the operator or surrounding people, objects, or the ground.

[0003] Those skilled in the art are aware of this risk and have conducted extensive research, including detecting the free fall of power tools and implementing measures such as automatically shutting off the motor power when free fall is detected and the power tool is determined to be falling. However, this approach only considers the protection of the power tool's motion output components from the ground, people, or objects, and does not provide active protection for the power tool itself.

[0004] Summary of the Invention

[0005] The purpose of this application is to solve the above problems.

[0006] This object is achieved by the claimed fall protection system and method for a power tool.

[0007] In a first aspect, a drop protection method for an electric tool of the present application is provided, comprising the following steps performed in sequence: a tool state determination step of measuring the vertical acceleration of the electric tool and determining whether the electric tool is in a free fall state based on the vertical acceleration; a motor state determination step of starting timing and determining whether the motor of the electric tool is in a starting state when it is determined that the electric tool is in a free fall state; a shutdown step of cutting off power to the motor of the electric tool when it is determined that the motor is in the starting state; a travel judgment step of determining whether the drop stroke of the electric tool reaches a preset travel threshold; an angular posture detection step of detecting the angular posture of the electric tool when it is determined that the drop stroke of the electric tool reaches the preset travel threshold; an angular posture judgment step of judging whether the angular posture of the electric tool is within a preset dangerous angular posture range; and a restarting step of restarting the motor when the angular posture of the electric tool is within the preset dangerous angular posture range.

[0008] In a second aspect, a drop protection system for an electric tool is provided, wherein the electric tool includes a motor and a motor switch for controlling the motor, and the drop protection system includes: a linear acceleration sensor for measuring the vertical acceleration of the electric tool; an angular acceleration sensor for measuring the angular posture of the electric tool; and a controller, which is communicatively connected to the linear acceleration sensor, the angular acceleration sensor and the motor switch and is configured to: receive the vertical acceleration of the electric tool from the linear acceleration sensor and determine whether the electric tool is in a free fall state by comparing the vertical acceleration with a preset gravity acceleration range; and determine whether the electric tool is in a free fall state after determining that the vertical acceleration is in a free fall state. The method comprises the following steps: starting the timing when the electric tool is in a free-fall state, receiving information from the motor switch about whether the motor of the electric tool is in a start-up state; controlling the motor switch to cut off the power to the motor of the electric tool when the motor is in the start-up state; judging whether the drop stroke of the electric tool has reached a preset drop stroke threshold; receiving the angular posture of the electric tool from the angular acceleration sensor and judging whether the angular posture is within a preset dangerous angular posture range when the drop stroke has reached the preset drop stroke threshold; and controlling the motor switch to restart the motor when the angular posture of the electric tool is within the preset dangerous angular posture range.

[0009] In a third aspect, an electric tool is provided, comprising: the above-mentioned drop protection system; a tool housing containing the motor; the motor switch for controlling the motor; and a transmission assembly configured to transmit the movement of the motor to the action output member of the electric tool.

[0010] The electric tool may be a hammer or a hammer drill, the transmission assembly may be an impact assembly, and when the motor of the fall protection system is restarted, the impact assembly is placed in a dry hammer mode for performing a reciprocating linear motion.

[0011] The drop protection system and method for electric tools of the present application, when detecting that the electric tool is in free fall and thus determining that the electric tool is falling, first cut off the power to the motor if the motor is in the starting state to stop the output action of the electric tool, and provide necessary protection for the ground or people or objects; at the same time, when determining that the electric tool has fallen, start timing to monitor the drop stroke (time or distance) of the electric tool and start detecting the angular posture of the electric tool when the drop stroke exceeds the preset drop stroke threshold, and judge whether the detected angular posture of the electric tool is within the preset dangerous angular posture range that will cause damage to the electric tool's own vulnerable parts. If the angular posture of the electric tool is within the preset dangerous angular posture range, the system of the present application will automatically restart the motor. According to the method of the present application, after the drop stroke exceeds the preset drop stroke threshold, it is generally considered that the height of the electric tool drop is sufficient to cause the electric tool to damage the electric tool's vulnerable parts (such as the aforementioned motor or battery, etc.) when it hits the ground, that is, it falls from a dangerous height. The preset dangerous angular posture range is set to the angular posture range within which vulnerable parts of the power tool would be damaged if it were to fall from the aforementioned dangerous height or higher and hit the ground (assuming the ground is hard and inelastic). This method includes restarting the motor when the angular posture of the power tool is within the dangerous angular posture range. The operation of the motor causes the power tool to generate vibration / momentum, which causes the power tool to change its angular posture while in free fall, thereby deviating from its original posture (within the dangerous angular posture range). As a result, the drop protection method of the present application provides active protection for the power tool itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG1 is a flow chart of a method for protecting a power tool from falling according to the present application. DETAILED DESCRIPTION

[0013] The power tool fall protection method of the present application is described below with reference to Figure 1. The present application is particularly directed to a power tool comprising a motor and a motor switch for controlling the motor.

[0014] 1 , in general, the drop protection method of the present application may include the following steps in sequence: a tool state determination step S1 for determining whether the power tool is in a falling (or free fall) state (or process); a motor state determination step S2 for starting timing and determining whether the motor is in a starting state (or powered on or operating or activated state) when the power tool is detected to be in a falling state; a shutdown step S3 for cutting off power to the motor when the detection result of the motor state determination step S2 shows that the motor is in a starting state; a stroke judgment step S4 for determining whether the drop stroke of the power tool reaches a preset stroke threshold; an angular posture detection step S5 for starting to detect the angular posture of the power tool when it is determined in the stroke judgment step S4 that the drop stroke of the power tool has reached (equal to or greater than) the above-mentioned stroke threshold; an angular posture judgment step S6 for determining whether the angular posture detected in the angular posture detection step S5 is within a preset dangerous angular posture range; a restart step S7 for restarting the motor when it is determined in the angular posture judgment step S6 that the angular posture detected in the angular posture detection step S5 is within the preset dangerous angular posture range.

[0015] Corresponding to the above-mentioned drop protection method, the drop protection system for electric tools of the present application includes a linear acceleration sensor for measuring the linear acceleration of the electric tool in the vertical direction (or Z direction), an angular acceleration (or angular attitude) sensor for measuring the angular attitude of the electric tool, and a controller. In some embodiments, the linear acceleration sensor and the angular acceleration sensor can be collectively referred to as an inertial measurement unit. The controller is connected in communication with the linear acceleration sensor and the angular acceleration sensor to obtain data on the vertical acceleration and angular attitude of the electric tool. The controller is also connected in communication with the motor switch of the electric tool for controlling the motor so as to obtain the on-off state of the motor switch and control the motor switch to switch it to the on and off position. The controller may include a clock and a memory. The clock or memory may be integrated with the controller or provided separately and connected in communication with the controller. The clock is used for timing, and the memory is used to store the preset parameter values ​​used in this drop protection method or the values ​​calculated in specific steps (such as the value of the drop distance) and the algorithm used in this method. In some embodiments, the memory may include a read-only memory for storing preset parameter values ​​or ranges (including gravitational acceleration ranges, time thresholds, distance thresholds, dangerous angle attitude ranges, etc.) and a random access memory for storing temporary measurements or calculated parameter values ​​(such as the timing duration or drop duration, drop distance, etc. mentioned herein). The motor switch of the power tool may be, but is not limited to, a FET switch or an IGBT switch.

[0016] The tool state determination step S1 of the drop protection method can be implemented as follows: using a linear acceleration sensor to measure the (real-time) vertical acceleration of the power tool in the vertical direction and sending the measured real-time vertical acceleration to the controller, the controller compares the received vertical acceleration with the preset gravity acceleration range, and when the vertical acceleration is within the preset gravity acceleration range, it is determined that the power tool is falling or in a free fall state or process.

[0017] The linear acceleration sensor can be an accelerometer, or other types of inertial measurement units known in the art for measuring linear acceleration. In some embodiments, the linear acceleration sensor in the form of an accelerometer measures not only the acceleration in the vertical direction (or commonly referred to as the Z direction), but also the acceleration in two mutually perpendicular horizontal directions (the X direction and the Y direction). In this application, the "gravity acceleration range" should be understood as being approximately equal to the zero acceleration that characterizes free fall motion or within a preset tolerance range of the zero acceleration. For example, taking into account measurement uncertainty or measurement error and other subjective or objective factors, the gravity acceleration range can be pre-set to be from -0.01g to +0.01g (where g is the acceleration of gravity of 9.81m / s 2 ) or from -0.1g to +0.1g or other similar ranges. For example, the preset gravity acceleration range can be stored in the above-mentioned memory.

[0018] In tool state determination step S1, the controller receives the power tool's real-time vertical acceleration from the linear acceleration sensor and compares it with a preset gravitational acceleration range. If the power tool's real-time vertical acceleration is within the preset gravitational acceleration range, the controller determines that the power tool is falling or in a free-fall state, then begins timing and executes motor state determination step S2. Otherwise, if the power tool's real-time vertical acceleration is outside the preset gravitational acceleration range, the controller determines that the power tool is not in a free-fall state, and the method ends at step S9.

[0019] In motor status determination step S2, the controller obtains the status of the motor switch of the power tool to which it is communicating, indicating whether it is on or off. The fact that the motor switch is on means that the power tool's motor is in the startup state and the power tool's motion output component is performing the intended reciprocating motion, such as a saw blade performing a reciprocating sawing motion, a chisel performing a reciprocating impact motion, or a drill bit rotating at high speed. Upon receiving the information from the motor switch that it is in the on state, the controller determines that the power tool is in the startup state and then executes shutdown step S3. Otherwise, if the motor switch is off, the method skips shutdown step S3 and proceeds directly to stroke determination step S4.

[0020] In the shutdown step S3 , the power tool is determined to be in a free fall state and the motor is in a starting state, and the controller sends a cut-off instruction to the motor switch, switching it to the cut-off state to stop or power off the motor of the power tool.

[0021] The method continues by using the controller to perform a stroke determination step S4. In this step, the controller compares the falling stroke of the power tool with a preset stroke threshold and determines whether the power tool has fallen to a dangerous height based on the comparison result. In this application, "stroke" can be time or distance. The controller can obtain the length of time that has passed since the power tool was in a free fall state by timing the clock, or the falling time of the power tool. The controller can directly compare the timing of its clock (or falling time) with a preset time threshold. The preset time threshold is set so that: when the clock timing reaches (equal to or greater than) the time threshold, it is considered that the power tool has fallen to a dangerous height, or the power tool is free-falling from this height onto a hard and inelastic ground (herein, the term "ground" refers generally to the surface onto which the power tool falls, which can be the ground, floor, table, etc.) and will damage or break the power tool's vulnerable parts (including but not limited to the motor, battery, sensor, housing, etc.). When the power tool falls from a height corresponding to less than the time threshold, it is considered that there is no damage to the power tool. Alternatively, the controller may be configured to first calculate the drop distance of the power tool based on the timing of its clock and the vertical acceleration of the power tool received from the linear acceleration sensor, and determine whether the distance reaches a preset distance threshold. The method of calculating the drop distance based on the above timing is known in the art, for example, distance = 0.5 × acceleration value × drop time 2 In some embodiments, the preset distance threshold may be about 1 meter, preferably about 0.8 meters, and more preferably about 0.6 meters.

[0022] In the case where the controller determines in the stroke judgment step S4 that the falling stroke of the power tool has exceeded the preset stroke threshold based on the recorded time of the clock or the calculated falling distance, the angular posture detection step S5 is continued. As known to those skilled in the art, the angular posture refers to the angular position or posture of the power tool (or the power tool coordinate system set or defined on the power tool) relative to the absolute coordinate system defined by the aforementioned X-direction, Y-direction and Z-direction. The angular posture detection step S5 can be implemented by a gyroscope. The gyroscope can measure the angular posture (or angular acceleration) of the power tool and send it to the controller. In the angular posture judgment step S6, the controller receives the (real-time) angular posture of the power tool measured by the gyroscope and determines whether the angular posture of the power tool is within the dangerous angular posture range. Power tools of different types or configurations have different preset dangerous angular posture ranges based on their different structures and different arrangements of vulnerable parts. Being within the dangerous angular posture range means that if the power tool falls and hits a hard and inelastic ground with any angular posture within the range, it will cause at least one component of the power tool or the component to be protected to be damaged or damage the ground due to direct impact with the ground. Typically, the preset "dangerous angular posture range" is the range in which the power tool needs to avoid hitting the ground in this posture, which can be the allowable tolerance range of a certain preset angular posture value, such as a tolerance range of ±10% of the specific preset angular posture value, preferably a tolerance range of ±5%.

[0023] If the angular posture of the power tool is determined to be within the dangerous angular posture range in angular posture determination step S6, the controller sends an on command to the motor switch to restart the power tool's motor, executing restart step S7. Turning on the power tool's motor switch restarts the motor. The activated motor causes the power tool to vibrate, which can change the posture of the power tool during free fall, causing it to deviate from its original posture within the dangerous angular posture range. This step or method can effectively provide active protection for the power tool itself, which includes a motor and is therefore typically heavy.

[0024] Return to the stroke determination step S4. If it is determined in this step that the falling stroke of the power tool does not reach the preset stroke threshold, the method will execute the impact detection step S8. In this step, the controller receives the vertical acceleration of the power tool from the linear acceleration sensor and compares it with the preset impact (acceleration) threshold. The preset impact threshold is set so that when the vertical acceleration value of the power tool reaches this threshold, it is considered or determined that the power tool has been impacted or has fallen to the ground. For example, the preset impact threshold can be an absolute value equal to or greater than 500g, preferably equal to or greater than 300g, more preferably greater than or equal to 200g, and most preferably greater than or equal to 50g. For another example, the impact threshold can be set to the reversal of the sign of the acceleration (for example, the sign of the acceleration changes from "+" to "-") or the reversal of the effective value. If the vertical acceleration value of the power tool reaches or meets the preset impact threshold, the method ends and the clock is reset to zero - ending step S9. If the vertical acceleration of the power tool does not reach or meet the preset impact threshold, the method continues to execute the stroke determination step S4.

[0025] If the power tool's state is outside the dangerous angular posture range in angular posture determination step S6, the method also proceeds to impact detection step S8. As described above, if the power tool's vertical acceleration reaches the preset impact threshold, the method terminates and the clock is reset. Conversely, if the power tool's vertical acceleration does not reach the preset impact threshold, the method proceeds to travel determination step S4.

[0026] The drop protection method of the present application is described above in conjunction with the drop protection system of the present application. The motor switch of the power tool and the various electrical components of the drop protection system (such as the linear acceleration sensor, angular acceleration sensor, controller, clock, memory, etc.) mentioned above can be powered by their own built-in batteries, or can be powered by a common built-in battery, or can be powered by an external battery separately provided in the power tool.

[0027] The present application also relates to a power tool including the present drop protection system. The power tool may include: a tool housing; a motor disposed within the tool housing; and a motor switch for controlling the start and stop of the motor. An action output member (e.g., a tool such as a drill bit, chisel, saw blade, etc.) configured to perform reciprocating translational and / or rotational motion when the motor is activated may be attached to or included in the power tool. The power tool may also include a transmission assembly disposed within the tool housing and engaged between the motor and the action output member to transmit the rotation of the motor to the action output member. The power tool also includes the above-mentioned drop protection system. Optionally, the power tool also includes the above-mentioned (external) battery for powering the electrical device and a battery housing for accommodating the battery. The battery housing may be integrally formed with the tool housing or provided separately and attached together. Each of the linear acceleration sensor and the angular acceleration sensor of the drop protection system may be disposed within either the battery housing or the tool housing. In one embodiment, the drop protection system may include first and second linear acceleration sensors disposed in the battery housing and the tool housing, respectively.

[0028] As described above, the power tool of the present application includes the drop protection system of the present application, and parameters including the aforementioned gravity acceleration range, drop time threshold or drop distance threshold, and dangerous angular posture range are preset and pre-stored in the drop protection system for a specific power tool. When the power tool falls or free falls, the power tool's motor is first forcibly powered off or shut down. In this way, when the drop distance of the power tool does not exceed the distance threshold, the ground that the power tool hits will not be damaged by the power tool, thereby protecting the ground. When the drop distance of the power tool exceeds the distance threshold (indicating that the power tool falls from a height exceeding the dangerous drop height), the drop protection system of the present application begins to detect the angular posture of the power tool. If the power tool is in an angular posture within the preset dangerous angular posture range, the power tool will damage its vulnerable parts or the ground after hitting the ground. In this case, the drop protection method restarts the power tool's motor, and by starting the motor to cause the power tool to vibrate, the angular posture of the power tool is changed, so that the angular posture of the power tool deviates from the preset dangerous angular posture range. This provides active protection for the power tool.

[0029] Furthermore, to ensure that the power tool is powered off before it hits the ground and to prevent the risk of accidental activation of the power tool, each time the restart step S7 (turning on the motor switch to restart the motor) is performed, the duration of the motor restart is very short, preferably no longer than 1 second, more preferably no longer than 0.5 seconds, and most preferably no longer than 0.1 seconds. Furthermore, to ensure that the angular posture of the power tool is adjusted to a position outside the dangerous angular posture range, in the restart step S7 (turning on the motor switch to restart the motor), each time the motor restarts, it automatically shuts down after the aforementioned short duration, and the method then proceeds to the angular posture determination step S6.

[0030] Furthermore, in order to enhance the vibration of the power tool so as to adjust the angular posture of the power tool more quickly, in the restarting step S7 in which the motor switch is turned on to restart the motor, it can be set so that the motor speed is increased to the maximum speed within a startup time shorter than the rated (soft) start time, for example, to a speed greater than the rated no-load (or idle) speed of the power tool. For example, the power tool is a DC motor tool that is constantly controlled by PWM modulation, and its normal rated no-load speed and operating speed are both N0, which is the speed at 70% PWM. Then, in the restarting step S7, 100% PWM can be started to achieve a higher speed. In this way, greater instantaneous vibration / momentum can be obtained. Additionally or alternatively, an additional vibration source can be provided to enhance the vibration of the power tool. The additional vibration source can be started in the restarting step S7 or after the restarting step S7.

[0031] As an example of a power tool, for example, a hammer or hammer drill, the transmission assembly that transmits motion between the motor and the action output member is an impact assembly including a striker that performs a reciprocating impact motion. The impact assembly of the power tool does not experience a dead-hammer process or mode when started at the rated no-load speed (N0) and rated soft-start time T of the power tool. However, for drop protection purposes, in the restarting step S7 of the present method, restarting the motor includes placing the power tool in a dead-hammer mode. In this mode, the output speed of the motor is increased to 1.2 times, preferably 1.5 times, the rated no-load speed (N0) in no more than 0.2 seconds, preferably no more than 0.1 seconds (approximately half the rated soft-start time T of the motor). The impact assembly exhibits a dead-hammer motion, enabling the action output member (i.e., the chisel) and the impact assembly (or striker) of the power tool to obtain significant instantaneous momentum, thereby enhancing the vibration of the power tool and facilitating faster / larger changes in the angular posture of the power tool.

[0032] The above description is provided in an illustrative manner. It should be understood that the terminology used is intended to be descriptive rather than restrictive. In light of the above teachings, many modifications and variations are possible. Therefore, within the scope of the appended claims, features or embodiments may be practiced in ways other than those specifically described.

Claims

1. A fall protection method for an electric tool, comprising the following steps performed in sequence: A tool state determination step (S1) of measuring the vertical acceleration of the electric tool and determining whether the electric tool is in a free fall state based on the vertical acceleration; When it is determined that the electric tool is in a free-fall state, a motor state determination step (S2) of starting timing and determining whether the motor of the electric tool is in a start state; A shutdown step (S3) of turning off the power of the motor of the electric tool when it is determined that the motor is in the starting state; A stroke determination step (S4) of determining whether the falling stroke of the electric tool reaches a preset stroke threshold; An angular posture detection step (S5) of detecting the angular posture of the electric tool when it is determined that the falling stroke of the electric tool has reached a preset stroke threshold; An angular posture determination step (S6) of determining whether the angular posture of the electric tool is within a preset dangerous angular posture range; A restarting step (S7) of restarting the motor when the angular posture of the electric tool is within the preset dangerous angular posture range.

2. The fall protection method according to claim 1, wherein: When it is determined in the stroke judgment step (S4) that the falling stroke of the power tool does not reach the preset stroke threshold, or when it is determined in the angular posture judgment step (S6) that the angular posture of the power tool is not within the preset dangerous angular posture range, the following is executed: an impact judgment step (S8) of comparing the vertical acceleration of the power tool with the preset impact threshold to determine whether the power tool has collided.

3. The drop protection method according to claim 2, wherein: In the impact judgment step (S8), the drop protection method is terminated when the vertical acceleration of the power tool reaches a preset impact threshold, and the stroke judgment step (S4) is performed when the vertical acceleration of the power tool does not reach the preset impact threshold.

4. The fall protection method according to any one of claims 1 to 3, wherein: In the restarting step (S7), the rotation speed of the motor is increased to a rotation speed value higher than the rated no-load rotation speed of the electric tool within a time shorter than the rated soft start time of the motor.

5. The fall protection method according to claim 4, wherein: In the restarting step (S7), the motor's rotational speed is increased to a speed value that is 1.2 times or 1.5 times the rated no-load speed within 0.5 times of its rated soft start time or within a time not exceeding 0.2 seconds, and the motor remains turned on for a time period not exceeding 1 second after being restarted.

6. The fall protection method according to claim 5, wherein: After the motor is restarted and kept powered on for the specified period of time, the angular posture determination step (S6) is performed.

7. The fall protection method according to any one of claims 1 to 6, wherein: In the stroke determination step (S4), determining whether the drop stroke of the electric tool reaches a preset stroke threshold comprises: Determine whether the drop duration obtained by timing reaches a preset time threshold; or The falling distance of the electric tool is calculated based on the falling duration obtained by the timing and the vertical acceleration of the electric tool measured in the tool state determination step (S1), and it is determined whether the falling distance reaches a preset falling distance threshold.

8. A fall protection system for an electric tool, the electric tool comprising a motor and a motor switch for controlling the motor, the fall protection system comprising: a linear acceleration sensor for measuring the vertical acceleration of the power tool; an angular acceleration sensor for measuring the angular attitude of the power tool; and a controller, which is in communication with the linear acceleration sensor, the angular acceleration sensor, and the motor switch and is configured to: receiving the vertical acceleration of the power tool from the linear acceleration sensor and determining whether the power tool is in a free fall state by comparing the vertical acceleration with a preset gravity acceleration range; When it is determined that the electric tool is in a free-fall state, starting timing, and receiving information from the motor switch as to whether the motor of the electric tool is in a start state; When the motor is in a started state, controlling the motor switch to cut off power to the motor of the electric tool; Determining whether the drop stroke of the electric tool reaches a preset drop stroke threshold; When the falling stroke reaches a preset falling stroke threshold, receiving the angular posture of the electric tool from the angular acceleration sensor and determining whether the angular posture is within a preset dangerous angular posture range; and When the angular posture of the electric tool is within a preset dangerous angular posture range, the motor switch is controlled to restart the motor.

9. The fall protection system according to claim 8, wherein: The controller includes a clock and / or a memory integrated therein or independently arranged and communicatively connected thereto.

10. The fall protection system according to claim 8, characterized in that At least one of the following: The linear acceleration sensor is an accelerometer; The angular acceleration sensor is a gyroscope; The preset gravity acceleration range is -0.01g to +0.01g or -0.1g to +0.1g; The preset dangerous angle attitude range is a tolerance range of 10% or ±5% of the preset angle attitude value; The preset drop distance threshold is 1 meter, 0.8 meter or 0.6 meter; and The impact threshold is 500g, 300g, 200g, or 50g, or the impact threshold is set to acceleration reversal.

11. An electric tool comprising: The fall protection system according to any one of claims 8 to 10; A tool housing, in which the motor is housed; The motor switch for controlling the motor; and A transmission assembly is configured to transmit the motion of the motor to the motion output member of the power tool.

12. The electric tool according to claim 11, wherein: Each of the motor switch, the linear acceleration sensor, the angular acceleration sensor, and the controller is powered by a respective built-in battery, or by a common built-in battery, or by an external battery included in the power tool.

13. The electric tool according to claim 11, wherein: The motor switches are FET or IGBT switches.

14. The electric tool according to any one of claims 11 to 13, wherein: The electric tool is a hammer or a hammer drill, the transmission assembly is an impact assembly, and when the motor of the fall protection system is restarted, the impact assembly is placed in a dry hammer mode for performing a reciprocating linear motion.

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