A holding detection method, device, equipment and tool for electric power tools

Abstract

This invention provides a method, apparatus, device, and tool for detecting the grip of power tools, relating to the field of power tool safety control technology. The method includes acquiring capacitance data from a capacitive sensing element on the inner side of the power tool handle housing. The capacitive sensing element comprises a perforated mesh-like sensing body and a closed wire connecting frame. The closed wire connecting frame is located on the outer periphery of the perforated mesh-like sensing body and is electrically connected to the edge nodes of the perforated mesh-like sensing body. The grip state is determined based on the amplitude, slope of change, and grip conditions in the capacitance data. The amplitude is determined based on a reference value, which is dynamically updated using a baseline dynamic update algorithm. This invention can effectively detect grip.

Description

Technical Field

[0001] This invention relates to the field of power tool safety control technology, and more specifically, to a method, apparatus, device, and tool for detecting the grip of power tools. Background Technology

[0002] In scenarios involving high-speed operation of power tools, determining whether the operator is in a valid grip is of paramount safety importance. If the tool is accidentally released due to vibration, reaction force, or operator error, without an effective grip detection mechanism, the tool will continue to operate, potentially causing cutting or rotating parts to continue moving uncontrollably, leading to serious personal injuries such as cuts, blows, or rebounds. By monitoring the grip status in real time, power tools can quickly trigger a stop or power cut-off the instant the operator releases their grip, fundamentally eliminating the high-risk hazard of "uncontrolled operation after release." This is not only a core element of active safety design for power tools but also a key technological safeguard for protecting operator safety and reducing workplace injury risks.

[0003] In existing technologies, grip detection solutions typically incorporate induction wires or induction plates within the tool handle. They determine whether continuous motor operation is permissible by detecting capacitance changes caused by a person approaching or gripping the tool. However, induction wires have a small sensing area and limited range, making them prone to missed grip detection when wearing thick gloves, with shifted grip positions, or when the handle casing is thick. Induction plates, on the other hand, have a larger sensing area and higher sensitivity, but they form a significant parasitic capacitance with the handle casing. When affected by factors such as motor heat, high ambient temperatures, or direct sunlight, the capacitance drift caused by changes in the dielectric constant of the casing material can be comparable to or even greater than the effective capacitance change due to human grip. This can easily lead to controller misjudgments, resulting in false holding, false activation, or failure of the off-hand protection mechanism. Summary of the Invention

[0004] The problem solved by this invention is how to effectively detect the grip state.

[0005] To address the aforementioned problems, this invention provides a method, apparatus, device, and tool for detecting the grip of power tools.

[0006] In a first aspect, the present invention provides a method for detecting the grip of power tools, comprising: Acquire capacitance data of a capacitive sensing element inside the housing of a power tool handle. The capacitive sensing element includes a hollowed-out mesh-shaped sensing body and a closed wire connection frame. The closed wire connection frame is located on the outer periphery of the hollowed-out mesh-shaped sensing body and is electrically connected to the edge node of the hollowed-out mesh-shaped sensing body. The gripping state is determined based on the amplitude, slope of change, and gripping conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

[0007] Optionally, acquiring the capacitance data of the capacitive sensing element inside the power tool handle housing includes: Obtain the original capacitance value of the capacitive sensing element; The amplitude is determined based on the original value of the capacitance and the reference value; The slope of change is determined based on the original value of the capacitance and the original value of the capacitance at the previous moment.

[0008] Optionally, the baseline dynamic update algorithm includes: When the slope of change is less than the action rate threshold and continues for a first preset number of sampling periods, the baseline value is updated according to the update formula. When the gripping state is determined, the update speed of the reference value is paused or reduced. The update formula includes: Base(t)=(1-alpha)×Base(t-1)+alpha×C(t); Where Base(t) is the updated baseline value, alpha is the update coefficient less than 1, Base(t-1) is the baseline value before the update, and C(t) is the original capacitance value of the capacitive sensing element.

[0009] Optionally, determining the grip state based on the amplitude, slope of change, and grip conditions in the capacitance data includes: When both the amplitude and the slope of change satisfy the holding condition and continue for a second preset number of sampling periods, the holding state is determined.

[0010] Optionally, the method further includes: When the motor is not running and is waiting for a trigger or switch command, it is determined to be in the start-up anti-accidental-touch state; If the gripping state is not determined when the anti-accidental touch state is activated, the motor is locked.

[0011] Optionally, the method further includes: When the motor is running, it is identified as being in operation monitoring status; In the operation monitoring state, if the gripping state is not determined, the PWM duty cycle of the motor is reduced according to a preset slope, the braking torque and preset stop time are output to the motor drive module of the motor, and the motor is locked. The preset stop time is set according to the type of power tool, moment of inertia and safety level.

[0012] Optionally, the method further includes: When any of the following occurs: the original capacitance value of the capacitor sensor is lower than the preset physical lower limit, the capacitor remains at a saturation value for a long period of time, the change of adjacent sample values ​​exceeds the hardware allowable range, or the detection channel fails to self-test, it is determined to be an abnormal protection state. Under the abnormal protection state, the motor is prohibited from starting or stopping.

[0013] In a second aspect, the present invention provides a grip detection device for power tools, comprising: The acquisition module is used to acquire capacitance data of a capacitive sensing sheet inside the housing of a power tool handle. The capacitive sensing sheet includes a hollowed-out mesh-shaped sensing body and a closed wire connection frame. The closed wire connection frame is located on the outer periphery of the hollowed-out mesh-shaped sensing body and is electrically connected to the edge nodes of the hollowed-out mesh-shaped sensing body. The determination module is used to determine the holding state based on the amplitude, change slope and holding conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

[0014] Thirdly, the present invention provides an electronic device, including a memory and a processor; The memory is used to store computer programs; The processor is configured to, when executing the computer program, implement the grip detection method for power tools as described in the first aspect.

[0015] Fourthly, the present invention provides a power tool, including the grip detection method for the power tool as described in the first aspect.

[0016] The beneficial effects of the present invention regarding the grip detection method, apparatus, device, and tool for power tools are: By acquiring the capacitance data of a capacitive sensing element located inside the handle housing of a power tool, which is composed of a perforated mesh-like sensing body and an outer closed wire connecting frame, the actual coupling area between the sensing conductor and the handle housing is reduced by the perforated mesh structure. This effectively reduces parasitic capacitance and the temperature drift caused by changes in the dielectric constant of the housing material, alleviating the problem of significant temperature drift of existing large-area solid plates, where the temperature drift can be comparable to or even greater than that of human grip signals. On the other hand, relying on the equivalent induced electric field formed by the outer closed wire connecting frame and the mesh structure, a large sensing range covering the grip area is maintained, improving the shortcomings of existing small-area sensing lines that have limited sensing range and are prone to missed grip detection in scenarios such as wearing thick gloves, grip position deviation, or thick handle housings. Based on this, the gripping state is determined by combining the amplitude and slope of change determined by the dynamic reference value with the preset gripping conditions. The reference value is dynamically updated through a baseline dynamic update algorithm. This can track slow capacitance drift caused by factors such as ambient temperature through the dynamically updated reference value. It can also effectively distinguish between slow temperature drift signals and sudden change signals caused by human gripping by using the dual judgment conditions of amplitude and slope of change. This further avoids the capacitance shift caused by temperature drift accumulation being misjudged as human gripping. Ultimately, this improves the reliability of gripping detection under high temperature and other working conditions and reduces the safety hazards of false holding, false activation or failure of the off-hand protection. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a grip detection method for power tools provided in an embodiment of the present invention. Figure 2 This is a schematic diagram showing the installation position of the capacitive sensing element provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the capacitive sensing element provided in an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a grip detection device for power tools provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 1. Handle shell; 2. Capacitive sensor sheet; 21. Hollowed-out mesh sensor body; 22. Closed wire connection frame; 3. Hand grip position. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0020] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0021] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0022] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0023] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0024] like Figure 1 As shown, an embodiment of the present invention provides a method for detecting the grip of power tools, comprising: Capacitance data of the capacitive sensing element 2 inside the housing 1 of the power tool handle is obtained. The capacitive sensing element 2 includes a hollowed-out mesh-shaped sensing body 21 and a closed wire connecting frame 22. The closed wire connecting frame 22 is disposed on the outer periphery of the hollowed-out mesh-shaped sensing body 21 and is electrically connected to the edge node of the hollowed-out mesh-shaped sensing body 21.

[0025] Specifically, the capacitance data is acquired by a capacitance sensing element located inside the handle housing through a capacitance detection module integrated within the power tool. For example... Figure 2 and Figure 3 As shown, the capacitive sensing sheet 2 preferably uses a flexible circuit board (FPC) as a conductive pattern carrier, and is attached to the inner wall of the power tool handle housing 1, facing the main coverage area of ​​the palm and fingers when the operator holds the tool normally, i.e., the hand grip position 3. In actual implementation, multiple independent capacitive sensing sheets 2 can also be set along the length of the handle according to the length and curved structure of the handle. Multiple sensing sheets can be connected in parallel to the same capacitance detection channel to expand the sensing area, or they can be connected to different detection channels to achieve zoned grip detection, adapting to different handle shapes and grip postures. The capacitive sensing sheet 2 comprises two parts: a hollowed-out mesh-shaped sensing body 21 and a closed wire connecting frame 22. The hollowed-out mesh-shaped sensing body 21 is composed of multiple intersecting conductive mesh lines. In this embodiment, the mesh lines adopt an orthogonal square arrangement, and the line width of the mesh lines is smaller than the width of the adjacent mesh openings, so that the overall sensing sheet forms a hollowing rate of more than 50%. In this embodiment, the hollowing rate is specifically set to 75%. In other alternative embodiments, the internal mesh structure can also adopt various forms such as diamond intersection, wavy line intersection, honeycomb, regular polygon mesh, circular hole array mesh, or non-uniform mesh with local density variation. As long as it forms a hollowed-out conductive sensing structure relative to the existing solid electrode plate, the same effect can be achieved. The closed wire connection frame 22 is continuously closed along the outer periphery of the hollowed-out grid-shaped sensing body 21, and the closed wire connection frame 22 is electrically connected to the edge nodes of all the internal grid lines one by one, so that all the grid lines and the outer connection frame together form the same uniform potential sensing electrode network. The closed wire connection frame 22 is made of the same conductive material as the internal grid lines, and its frame shape is a rounded rectangle adapted to the grip area of ​​the handle. In other embodiments, it can also be set as an ellipse, a ring, or an irregular closed shape that completely fits the curved surface of the handle. It can also be equivalently closed connected by multiple separate conductive frames through bridging wires.

[0026] In alternative hardware carriers, besides flexible circuit boards, the capacitive sensing element 2 can also be implemented using various carriers capable of forming predetermined conductive patterns, such as rigid PCBs, conductive silver paste printed layers on flexible insulating films, conductive carbon paste printed layers, stamped metal sheets, and laser-formed conductive layers. Regardless of the carrier used, the conductive pattern includes a core structure consisting of an internal hollowed-out mesh body and an outer closed connecting frame. Regarding installation, the capacitive sensing element 2 can be directly attached to the inner wall of the handle shell using adhesive, or mechanically fixed through hot-press bonding, slot limiting, screw pressing, injection molding insert pre-embedding, or plug-in terminal fixing. It can also be embedded inside the handle shell's interlayer, positioned between the outer rubber layer and the inner rigid plastic layer, or fixed to an insulating support bracket inside the handle and close to the inner wall of the shell. The detection input terminal of the capacitance detection module is electrically connected to the electrode lead-out terminal of the capacitive sensing element 2, periodically acquiring the original capacitance value of the capacitive sensing element 2 at a fixed sampling period, or acquiring count values ​​and charge / discharge duration values ​​corresponding to the capacitance value, thus completing the capacitance data acquisition process. This embodiment reduces the actual coupling area between the sensing conductor and the handle shell through a high-permeability mesh structure, significantly reducing the reference parasitic capacitance and the capacitance drift caused by temperature changes. At the same time, it maintains the equivalent sensing range covering the entire grip area by utilizing the edge electric field effect of the outer closed connecting frame. Without increasing hardware costs and structural complexity, it simultaneously takes into account both a large sensing range and low temperature drift characteristics, effectively improving the inherent contradictions of easy missed detection of small-area sensing lines and severe temperature drift of large-area solid plates in the prior art.

[0027] The gripping state is determined based on the amplitude, slope of change, and gripping conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

[0028] Specifically, based on the capacitance data obtained in the aforementioned steps, the amplitude parameter corresponding to the dynamic reference value and the slope parameter reflecting the rate of capacitance change are extracted. These two parameters are then compared one by one with preset grip judgment conditions to ultimately determine whether the current state is a valid human grip. The reference value used to calculate the amplitude is not a factory-fixed constant, but a dynamic reference obtained through a baseline dynamic update algorithm that adjusts in real time according to changes in environmental parameters. This continuously adapts to capacitance reference shifts caused by factors such as environmental temperature and humidity, and device aging. This embodiment combines amplitude and slope dimensions for grip judgment and adapts to slow environmental drift through dynamically updated reference values, improving the accuracy of grip state judgment from both hardware structure and algorithm logic perspectives, and reducing the probability of misjudgment caused by temperature changes.

[0029] In this embodiment, by acquiring the capacitance data of the capacitive sensing sheet located inside the handle housing of the power tool, which is composed of a hollowed-out mesh-shaped sensing body and an outer closed wire connecting frame, the actual coupling area between the sensing conductor and the handle housing is reduced by the hollowed-out mesh structure. This effectively reduces parasitic capacitance and the temperature drift caused by the change in the dielectric constant of the housing material, alleviating the problem of significant temperature drift of existing large-area solid plates, where the temperature drift can be comparable to or even greater than the human grip signal. On the other hand, relying on the equivalent induced electric field formed by the outer closed wire connecting frame and the mesh structure, a large sensing range covering the grip area is maintained, improving the shortcomings of existing small-area sensing lines that have limited sensing range and are prone to missed grip detection in scenarios such as wearing thick gloves, grip position deviation, or thick handle housings. Based on this, the gripping state is determined by combining the amplitude and slope of change determined by the dynamic reference value with the preset gripping conditions. The reference value is dynamically updated through a baseline dynamic update algorithm. This can track slow capacitance drift caused by factors such as ambient temperature through the dynamically updated reference value. It can also effectively distinguish between slow temperature drift signals and sudden change signals caused by human gripping by using the dual judgment conditions of amplitude and slope of change. This further avoids the capacitance shift caused by temperature drift accumulation being misjudged as human gripping. Ultimately, this improves the reliability of gripping detection under high temperature and other working conditions and reduces the safety hazards of false holding, false activation or failure of the off-hand protection.

[0030] Optionally, acquiring the capacitance data of the capacitive sensing element 2 inside the power tool handle housing 1 includes: Obtain the original capacitance value of the capacitive sensing element 2; The amplitude is determined based on the original value of the capacitance and the reference value; The slope of change is determined based on the original value of the capacitance and the original value of the capacitance at the previous moment.

[0031] Specifically, when acquiring the capacitance data of the capacitive sensing element 2, the original capacitance value C(t) at the corresponding moment is collected in each sampling cycle, where t is the sequence number of the current sampling cycle. The sampling cycle can be set according to the computing power of the controller and the real-time detection requirements, and is usually in the millisecond range. Based on the collected original capacitance value, the relative amplitude at the current moment is first calculated: the difference between the current original capacitance value C(t) and the non-touch reference value Base(t) of the current cycle is calculated to obtain the relative amplitude DeltaC, that is, DeltaC=C(t)-Base(t). This amplitude characterizes the degree of deviation of the current capacitance value relative to the non-human contact reference, and can intuitively reflect the magnitude of the capacitance increment caused by the human body approaching or holding the handle. The slope of change at the current moment is then calculated: the difference between the original capacitance value C(t) of the current sampling period and the original capacitance value C(t-1) of the previous sampling period is calculated to obtain the slope S between adjacent periods, i.e., S = C(t) - C(t-1). This slope characterizes the rate of change of capacitance value within a unit sampling period and can be used to distinguish between slow environmental drift and rapid human gripping action. In actual implementation, the original capacitance value can be a directly collected capacitance value, or a count value, RC charging and discharging time value, or oscillation period value output by the capacitance detection circuit that corresponds one-to-one with the capacitance value. The relative difference is consistent with the calculation logic of the slope of change, and only the dimensions of the threshold need to be adjusted accordingly. This embodiment can extract the amplitude reflecting the degree of offset and the slope reflecting the rate of change from the original capacitance data through calculation, providing two independent dimensions of judgment basis for subsequent grip determination. At the same time, the calculation method is simple and efficient, which can be quickly executed in low-cost microcontrollers and is fully adapted to the real-time control requirements of power tools.

[0032] Optionally, the baseline dynamic update algorithm includes: When the slope of change is less than the action rate threshold and continues for a first preset number of sampling periods, the baseline value is updated according to the update formula. When the gripping state is determined, the update speed of the reference value is paused or reduced. The update formula includes: Base(t)=(1-alpha)×Base(t-1)+alpha×C(t); Where Base(t) is the updated baseline value, alpha is the update coefficient less than 1, Base(t-1) is the baseline value before the update, and C(t) is the original capacitance value of the capacitive sensing element 2.

[0033] Specifically, the baseline dynamic update algorithm uses the capacitance change slope as the core judgment criterion, adaptively adjusting the update speed of the reference value to achieve a balance between slow drift tracking and fast action retention. Specifically, after calculating the change slope S in each sampling period, the absolute value of the change slope |S| is compared with a preset action rate threshold Vth. When |S| is less than the action rate threshold Vth, and this state continues for a first preset number M sampling periods, it is determined that the change in the current capacitance value originates from slow drift caused by factors such as ambient temperature, humidity, or device aging. At this time, the reference value is slowly updated using a preset update formula, which is: Base(t) = (1-alpha) × Base(t-1) + alpha × C(t); where Base(t) is the updated reference value for the current period, Base(t-1) is the historical reference value for the previous period, C(t) is the original capacitance value for the current period, and alpha is an IIR filter update coefficient less than 1. In practical applications, this coefficient can be flexibly adjusted within the range of 0.001 to 0.05 according to the product's environmental adaptability and response speed requirements. When the system determines that the current state is one where the human is holding the object, it immediately pauses the update of the reference value, setting the update coefficient alpha to 0, or significantly reducing the update speed of the reference value so that the alpha value is less than one-tenth of that during slow updates. This prevents the rapid capacitance increment generated by the human grip from being offset by the reference value tracking, thus preventing the grip signal from being overwhelmed. When the system subsequently determines that the object is no longer in the hand and the capacitance value has stabilized after a preset recovery time, the slow update logic of the reference value is resumed. This embodiment can accurately identify slow environmental drift and rapid gripping actions by changing the slope, achieving adaptive dynamic updates of the reference value. It can continuously track the reference offset caused by slow-changing factors such as temperature drift, without offsetting the effective detection signal generated by the human grip. Combined with the hardware structure of the hollowed-out mesh plate, it can further improve the anti-interference capability of grip detection under high temperature and rapid heating conditions.

[0034] Optionally, determining the grip state based on the amplitude, slope of change, and grip conditions in the capacitance data includes: When both the amplitude and the slope of change satisfy the holding condition and continue for a second preset number of sampling periods, the holding state is determined.

[0035] Specifically, when determining the grip state, both amplitude and slope conditions must be verified simultaneously, and the anti-shake requirements for continuous sampling periods must be met to avoid misjudgments caused by transient interference. Preset grip conditions include a grip amplitude threshold Th_amp and a grip slope threshold Th_slope. When the calculated relative amplitude DeltaC is greater than the grip amplitude threshold Th_amp, and the slope S is simultaneously greater than the grip slope threshold Th_slope, the current single sampling period is determined to meet the single grip trigger condition. To avoid false triggers caused by environmental electromagnetic interference, tool vibration, or transient noise, the system counts the sampling periods that continuously meet the conditions. When the state where both amplitude and slope simultaneously meet the grip conditions continues for a second preset number N sampling periods, the current state is finally determined to be an effective human grip state. In practical applications, this value can be adjusted within the range of 2 to 10 according to the product's response speed and anti-shake requirements. Correspondingly, when determining the release state, corresponding release amplitude thresholds and negative slope thresholds can be set. When the capacitance value falls below the release threshold and continues for the corresponding sampling period, it is determined to be a release state. The above-mentioned thresholds can be written into the controller storage unit through factory calibration, or they can be adaptively adjusted according to the current environmental parameters through power-on self-learning. This embodiment can determine the grip by combining the dual thresholds of amplitude and slope with a continuous sampling anti-shake mechanism. This can effectively filter the capacitance offset caused by the accumulation of slow temperature drift, avoid the misjudgment caused by temperature drift crossing the threshold in the traditional scheme that only relies on a single amplitude value, and greatly improve the reliability of grip detection under high temperature and high load conditions.

[0036] For example, the off-hand protection judgment and motor control can be performed in a state machine manner through the safety control module integrated inside the power tool. The state machine includes at least an anti-accidental touch state, an operation monitoring state, and an abnormal protection state; wherein, the anti-accidental touch state corresponds to the stage where the motor is not running and waiting for the trigger or switch command, the operation monitoring state corresponds to the stage where the motor has output drive, and the abnormal protection state corresponds to the stage where the capacitor detection channel is disconnected, short-circuited, or the value exceeds the limit.

[0037] Optionally, the method further includes: When the motor is not running and is waiting for a trigger or switch command, it is determined to be in the start-up anti-accidental-touch state; If the gripping state is not determined when the anti-accidental touch state is activated, the motor is locked.

[0038] Specifically, when the motor of the power tool is not running and the system is in standby mode waiting for the user to trigger the trigger or operate the switch to start the motor, it automatically enters the start-up anti-accidental touch state. In this state, the capacitance data of the capacitive sensing element 2 is continuously collected at fixed intervals, and the grip determination logic described above is used to determine in real time whether the handle is in a valid grip state. If the determination fails to confirm a grip state, i.e., no valid grip of the handle is detected, the start-up lock operation is performed on the motor drive circuit. Specifically, this can be achieved by shielding the PWM drive signal output of the motor drive or turning off the enable control port of the power switch, so that the motor drive circuit cannot output drive current. At this time, even if the user accidentally touches the trigger or start switch, the motor cannot start running. Only when the system continuously determines that the grip state is valid will the start-up lock of the motor be released, allowing the response to the start command of the trigger or switch to enter the normal operation state. This embodiment introduces grip detection and verification during the standby waiting-to-start phase of the power tool, avoiding accidental start-up of the tool due to accidental switch contact or foreign object squeezing the switch when the tool is placed away from the hand, improving the safety protection capability of the tool in standby mode and reducing the risk of personal injury caused by accidental start-up.

[0039] Optionally, the method further includes: When the motor is running, it is identified as being in operation monitoring status; In the operation monitoring state, if the gripping state is not determined, the PWM duty cycle of the motor is reduced according to a preset slope, the braking torque and preset stop time are output to the motor drive module of the motor, and the motor is locked. The preset stop time is set according to the type of power tool, moment of inertia and safety level.

[0040] Specifically, when the power tool's motor is running normally, it enters a monitoring state, continuously detecting and determining the handle gripping status in real time. In this monitoring state, if it's determined that the handle is not currently gripped—that is, if the operator accidentally releases their hand or intentionally lets go—a graded automatic braking protection process is executed, rather than directly cutting off the power and allowing the motor to coast to a stop. More specifically, the target motor speed is first set to zero, and the PWM duty cycle of the motor drive is gradually reduced according to a preset slope. Simultaneously, a reverse braking torque is output to the motor drive module, causing the motor to enter an automatic electric braking state. This controls the working parts of the power tool (such as grinding discs, drill bits, saw blades, etc.) to completely stop rotating within a preset stop time. Once the preset stop time is reached and the motor is confirmed to have stopped, the power output of the motor drive circuit is cut off and the motor is locked, preventing it from restarting. The preset stop time is not a fixed value, but is set comprehensively based on the specific type of power tool, the rotational inertia of the working parts, and the product's safety level. For example, tools with high rotational inertia, such as angle grinders, can be set with a slightly longer stop time, while low-power electric drills can be set with a shorter stop time. This ensures braking effectiveness while avoiding excessive braking impact that could damage the transmission structure. This embodiment can actively brake and stop the tool when it is released from the hand during operation. Compared to free stopping, this significantly reduces the stopping time of the working parts, lowering the risk of personal injury caused by the tool continuing to operate after the user releases the hand. Furthermore, the tiered braking method can be adapted to different types of power tools, balancing braking safety and mechanical lifespan.

[0041] Optionally, the method further includes: When any of the following occurs: the original capacitance value of the capacitor sensing element 2 is lower than the preset physical lower limit, it remains at a saturation value for a long time, the change of adjacent sampled values ​​exceeds the hardware allowable range, or the detection channel fails to self-test, it is determined to be an abnormal protection state. Under the abnormal protection state, the motor is prohibited from starting or stopping.

[0042] Specifically, during operation, the hardware status of the capacitance detection circuit is periodically self-checked in real time. When any of the following abnormal situations are detected, the system immediately enters an abnormal protection state: First, the original capacitance value collected by the capacitance sensor 2 is continuously lower than the preset physical lower limit. This usually corresponds to a broken sensing electrode, a detached connecting wire, or an open circuit in the detection channel. Second, the original capacitance value remains at its maximum saturation value for a long time and cannot fall back. This usually corresponds to a short circuit to ground of the sensing electrode or a fault in the detection channel. Third, the change in capacitance value between two adjacent sampling periods exceeds the maximum allowable range of the hardware. This usually corresponds to an abnormal detection circuit or strong electromagnetic interference. Fourth, the power-on self-test or periodic self-test verification of the capacitance detection channel fails. In the abnormal protection state, if the motor is currently not running, the motor is directly prohibited from starting, and a fault indication is output through an indicator light or buzzer. If the motor is currently running, the output reduction and active braking shutdown process, consistent with the off-hand protection, is triggered to control the motor to stop smoothly within a safe time. Subsequently, the motor drive circuit is locked to prevent the tool from losing its off-hand protection after detection failure. This embodiment can perform real-time fault monitoring of the hardware circuit for grip detection. When faults such as open circuits or short circuits occur in the sensor, connecting wires, or detection circuit, safety protection is triggered in a timely manner to avoid the loss of the off-hand protection function due to damage to the detection components, thereby further improving the overall redundancy and reliability of the power tool safety system.

[0043] like Figure 4 As shown, an embodiment of the present invention provides a grip detection device for power tools, comprising: The acquisition module is used to acquire the capacitance data of the capacitive sensing sheet 2 inside the housing 1 of the power tool handle. The capacitive sensing sheet includes a hollow mesh-shaped sensing body 21 and a closed wire connection frame 22. The closed wire connection frame 22 is disposed on the outer periphery of the hollow mesh-shaped sensing body 21 and is electrically connected to the edge node of the hollow mesh-shaped sensing body 21. The determination module is used to determine the holding state based on the amplitude, change slope and holding conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

[0044] like Figure 5 As shown, an electronic device 500 provided in this embodiment of the invention includes a memory 510 and a processor 520; the memory 510 is used to store a computer program; the processor 520 is used to implement the grip detection method for power tools as described above when the computer program is executed.

[0045] Alternatively, an electronic device 500 includes a memory 510 and a processor 520 coupled to the memory 510; the memory 510 is configured to store a computer program; and the processor 520 is configured to perform the following operations when the computer program is executed: Acquire capacitance data of the capacitive sensing sheet 2 inside the housing 1 of the power tool handle. The capacitive sensing sheet includes a hollow mesh-shaped sensing body 21 and a closed wire connection frame 22. The closed wire connection frame 22 is disposed on the outer periphery of the hollow mesh-shaped sensing body 21 and is electrically connected to the edge node of the hollow mesh-shaped sensing body 21. The gripping state is determined based on the amplitude, slope of change, and gripping conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

[0046] Electronic device 500, which can serve as a server or client of the present invention, is described below as an example of a hardware device applicable to various aspects of the present invention. Electronic device 500 is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic device 500 can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0047] Electronic device 500 includes a computing unit that can perform various appropriate actions and processes based on a computer program stored in read-only memory (ROM) or a computer program loaded from a storage unit into random access memory (RAM). The RAM may also store various programs and data required for device operation. The computing unit, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0048] An embodiment of the present invention provides an electric tool, including the grip detection method for the electric tool as described in the first aspect.

[0049] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units.

[0050] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for detecting the grip of power tools, characterized in that, include: Acquire capacitance data of the capacitive sensing sheet (2) inside the housing (1) of the power tool handle, wherein the capacitive sensing sheet (2) includes a hollow mesh-shaped sensing body (21) and a closed wire connecting frame (22), the closed wire connecting frame (22) is disposed on the outer periphery of the hollow mesh-shaped sensing body (21), and the closed wire connecting frame (22) is electrically connected to the edge node of the hollow mesh-shaped sensing body (21); The gripping state is determined based on the amplitude, slope of change, and gripping conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

2. The method for detecting the grip of power tools according to claim 1, characterized in that, The process of acquiring capacitance data of the capacitive sensing plate (2) inside the power tool handle housing (1) includes: Obtain the original capacitance value of the capacitive sensing element (2); The amplitude is determined based on the original value of the capacitance and the reference value; The slope of change is determined based on the original value of the capacitance and the original value of the capacitance at the previous moment.

3. The method for detecting the grip of power tools according to claim 1, characterized in that, The baseline dynamic update algorithm includes: When the slope of change is less than the action rate threshold and continues for a first preset number of sampling periods, the baseline value is updated according to the update formula. When the gripping state is determined, the update speed of the reference value is paused or reduced. The update formula includes: Base(t)=(1-alpha)×Base(t-1)+alpha×C(t); Where Base(t) is the updated baseline value, alpha is the update coefficient less than 1, Base(t-1) is the baseline value before the update, and C(t) is the original capacitance value of the capacitor sensing sheet (2).

4. The method for detecting the grip of power tools according to claim 1, characterized in that, The step of determining the grip state based on the amplitude, slope of change, and grip conditions in the capacitance data includes: When both the amplitude and the slope of change satisfy the holding condition and continue for a second preset number of sampling periods, the holding state is determined.

5. The method for detecting the grip of power tools according to claim 1, characterized in that, Also includes: When the motor is not running and is waiting for a trigger or switch command, it is determined to be in the start-up anti-accidental-touch state; If the gripping state is not determined when the anti-accidental touch state is activated, the motor is locked.

6. The method for detecting the grip of power tools according to claim 1, characterized in that, Also includes: When the motor is running, it is identified as being in operation monitoring status; In the operation monitoring state, if the gripping state is not determined, the PWM duty cycle of the motor is reduced according to a preset slope, the braking torque and preset stop time are output to the motor drive module of the motor, and the motor is locked. The preset stop time is set according to the type of power tool, moment of inertia and safety level.

7. The method for detecting the grip of power tools according to claim 1, characterized in that, Also includes: When any of the following occurs: the original capacitance value of the capacitor sensing sheet (2) is lower than the preset physical lower limit, the saturation value is maintained for a long time, the change of adjacent sampled values ​​exceeds the hardware allowable range, or the detection channel fails to self-test, it is determined to be an abnormal protection state. Under the abnormal protection state, the motor is prohibited from starting or stopping.

8. A grip detection device for power tools, characterized in that, include: The acquisition module is used to acquire the capacitance data of the capacitive sensing sheet (2) inside the housing (1) of the power tool handle. The capacitive sensing sheet includes a hollow mesh-shaped sensing body (21) and a closed wire connecting frame (22). The closed wire connecting frame (22) is located on the outer periphery of the hollow mesh-shaped sensing body (21) and is electrically connected to the edge node of the hollow mesh-shaped sensing body (21). The determination module is used to determine the holding state based on the amplitude, change slope and holding conditions in the capacitance data, wherein the amplitude is determined based on a reference value, and the reference value is dynamically updated according to a baseline dynamic update algorithm.

9. An electronic device, characterized in that, Including memory and processor; The memory is used to store computer programs; The processor is configured to, when executing the computer program, implement the grip detection method for power tools as described in any one of claims 1 to 7.

10. A power tool, characterized in that, Including the grip detection method for power tools as described in any one of claims 1 to 7.

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