System for protecting operator of power tool

Abstract

To provide a system for protecting an operator of a power tool.SOLUTION: A system for protecting an operator 110 of a power tool may include: a wearable sensor 120 of a first set worn by the operator 110; a wearable sensor 130 of a second set worn by the operator 110; a first tool sensor 122 which is arranged in the power tool and is configured so that the first tool sensor 122 communicates with the wearable sensor 120 of the first set; a second tool sensor 132 which is arranged in the power tool and is configured so that the second tool sensor 132 communicates with the wearable sensor 130 of the second set; and a controller 140. The controller 140 may be configured to determine whether a protective action is started on the power tool on the basis of a distance between the first tool sensor 122 and the wearable sensor 120 of the first set and a distance between the second tool sensor 132 and the wearable sensor 130 of the second set.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Exemplary embodiments relate generally to power equipment, and more particularly to a system configured to intelligently protect a user of a chainsaw or other power equipment, such as a power cutter with a blade or chain. [Background technology]

[0002] Maintenance tasks of a particular nature are typically performed using a variety of tools and / or machines configured to perform corresponding specific tasks. Some such tools, such as chainsaws, are designed to be effective at cutting wood in what may be a relatively short period of time or may take a long time, including in some cases a full day's work. When operating a chainsaw for extended periods of time, fatigue may affect the safe operation of the equipment. However, regardless of the length of time an operator uses the equipment, it is important that the operator be vigilant in implementing safe operating procedures to prevent injury to themselves and others.

[0003] To help improve safety, operators are encouraged to wear protective clothing and other personal protective equipment (PPE). However, some operators may find the PPE uncomfortable and, depending on the weather, may work wearing very light clothing over the upper body. For this reason, it may be desirable to prescribe additional "intelligent" protective solutions that do not rely on PPE to protect users of chainsaws and other outdoor power equipment. Summary of the Invention

[0004] In some exemplary embodiments, a system for protecting an operator of a power tool may be provided. The system may include a first set of wearable sensors worn by the operator, a second set of wearable sensors worn by the operator, a first tool sensor disposed on the power tool where the first tool sensor is configured to communicate with the first set of wearable sensors, a second tool sensor disposed on the power tool where the second tool sensor is configured to communicate with the second set of wearable sensors, and a controller. The controller may be configured to determine whether to initiate a protective action on the power tool based on a distance between the first tool sensor and the first set of wearable sensors and a distance between the second tool sensor and the second set of wearable sensors.

[0005] In one exemplary embodiment, another system for protecting a power tool operator may be provided. The system may include a plurality of distance sensors worn by the operator, a reader disposed on the power tool, and a controller configured to determine whether to initiate a protective action on the power tool based on a distance between each of the distance sensors and the reader. The controller may be configured to implement an adaptive power control cycle to determine the distance between each of the distance sensors and the reader.

[0006] In another exemplary embodiment, yet another system for protecting an operator of a power tool may be provided. The system may include a plurality of inertial measurement unit (IMU) based sensors worn by the operator, a tool position sensor disposed on the power tool, and a controller. The controller may be configured to determine whether to initiate a protective action on the power tool based on measurements between the IMU-based sensors and the tool position sensor. The IMU-based sensors and the tool position sensor may be periodically calibrated based on a predefined posture of the operator and a corresponding position of the power tool.

[0007] Some exemplary embodiments may improve user experience, safety and / or productivity during use of outdoor power equipment. [Brief description of the drawings]

[0008] Having thus described several exemplary embodiments in general terms, reference is now made to the accompanying drawings, which are not necessarily drawn to scale. [Figure 1] FIG. 1 is a conceptual diagram of a system in which a wearable sensor may operate in accordance with an illustrative embodiment. [Diagram 2] FIG. 1 is a block diagram of a system for providing operator protection according to an exemplary embodiment. [Diagram 3] 1 is a schematic diagram illustrating how known distances at defined poses can be used to calibrate a sensor in accordance with an exemplary embodiment; [Figure 4] FIG. 1 is a block diagram of a method for calibrating a sensor according to an exemplary embodiment. [Diagram 5] FIG. 13 is a block diagram of a set of rules that may be applied in an application for balancing two different sets of sensors in accordance with an example embodiment. [Figure 6] FIG. 13 is a control flow diagram of a scheme involving detection of the distance between a reader and an electronic tag in accordance with an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Some exemplary embodiments will now be more generally described below with reference to the accompanying drawings. Some, but not all, exemplary embodiments are shown in the accompanying drawings. Indeed, the examples described and illustrated herein should not be construed as limiting on the scope, applicability, or configuration of the present disclosure. Rather, such exemplary embodiments are provided so that the present disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. Furthermore, the term "or" as used herein should be construed as a logical operator that is true whenever one or more of its operands are true. As used herein, operative coupling should be understood in each case to relate to a direct or indirect connection that allows for a functional interconnection or interaction of the components that are operatively coupled to each other.

[0010] In some exemplary embodiments, an intelligent protection system may be provided that is configured to monitor the position of a guide bar or blade (or other working assembly) of a chainsaw (or other power equipment) relative to a user's body part. The system is configured to detect when a user's body part gets too close to the guide bar or blade, or when a situation occurs in which stopping the chain is desirable. Thus, both the user and PPE can be protected during operation of various types of cutting equipment.

[0011] With respect to the goals discussed above, one solution may be to place Inertial Measurement Unit (IMU) based tracking sensors on the device (e.g., near the guide bar or blade) and on the body part to be protected. IMU based sensors may include a 3-axis accelerometer, gyroscope and / or magnetometer to track three-dimensional movement. This type of tracking is commonly used in ergonomics and sports studies, and is used in special effects in movies and computer games to track body movements. Placing sensors on or near the guide bar or blade as well would allow tracking of the body's movements relative to the guide bar or blade, and thus prescribing protective actions if such tracking indicates a potential intersection between the guide bar or blade and a body part. Additionally, volumes may be modeled around each of the body parts and the guide bar or blade to prescribing a protected volume (e.g., defined by the body part (or other object) and a predefined distance around the body part / object) within which protective actions are implemented in the event of an intrusion.

[0012] However, there are known issues with accuracy associated with IMU-based tracking sensors. In this regard, pure IMU-based motion computation solutions (i.e., dead reckoning) introduce computation errors due to sensor inaccuracies, noise, and limitations associated with the computation platform. For this reason, in some exemplary embodiments, a system may be defined that allows for calibration of the IMU-based tracking sensor to enable calibrated motion tracking. Additionally or alternatively, a system may be defined that employs sensor fusion to combine the IMU-based tracking sensor with other sensors (e.g., distance measurement sensors) to improve accuracy with respect to tracking and initiation of protection functions.

[0013] By improving accuracy and providing redundancy, one can potentially realize the future possibility of defining a system that is both accurate and reliable enough to operate without PPE. Thus, example embodiments may include providing sensor fusion by combining different types of sensors and tracking mechanisms. Example embodiments may also include providing tracking algorithms and / or methods that employ sensors to accurately measure distance using adaptive signal strength measurements.

[0014] FIG. 1 shows an exemplary embodiment of the intelligent protection system applied when the outdoor power equipment is a chain saw 100 having an endless chain 102 rotating around a guide bar to perform a cutting operation. As shown in FIG. 1, an operator 110 wears two sets of wearable sensors. In this regard, the operator 110 wears a helmet 112, gloves 114, and boots 116 as examples of PPE. The sensors may be integrated into or attached to the PPE. Of course, the sensors may be integrated into or attached to other clothing or equipment, or may be implemented in other locations as well. Therefore, the specific example shown in FIG. 1 should be understood as non-limiting with respect to the number of sensors, the location of the sensors, and the manner in which the sensors are attached to the operator 110 and / or the equipment of the operator 110.

[0015] In this example, the two sets of body-worn sensors include a first set of body-worn sensors that are IMU-based sensors 120. The IMU-based sensors 120 in FIG. 1 are located on the helmet 112, gloves 114, and boots 116 worn by the operator 110, but as noted above, may be located elsewhere. Thus, for example, additional IMU-based sensors 120 may be provided on the knees, elbows, chest, or other desired locations of the operator 110. The IMU-based sensors 120 may work in conjunction with a tool position sensor 122 that may be located on a portion of the tool (e.g., the chainsaw 100). Notably, the tool position sensor 122 may itself be an IMU-based sensor and / or include a set of such sensors. The IMU-based sensors 120 and the tool position sensor 122 may each be configured to perform motion tracking in three dimensions to enable tracking of the relative position between the body part on which the IMU-based sensors 120 are located and the tool. Motion tracking may be performed in connection with the application of motion tracking algorithms to the three-dimensional linear acceleration and angular velocity data.

[0016] The two sets of wearable sensors also include a second set of wearable sensors that are distance sensors 130. Although the distance sensors 130 in this example are shown to be at the same locations on the operator 110 as the IMU-based sensors 120, such correspondence is not required. As such, there may be more or fewer distance sensors 130 than the IMU-based sensors 120, and the distance sensors 130 may be at the same or different locations on the operator 110. The distance sensors 130 may be configured to operate in conjunction with a tool distance sensor 132, which may be located on a portion of a tool (e.g., the chainsaw 100). In this example, the tool distance sensor 132 is located on a guide bar of the chainsaw 100, such that a distance measurement performed between the tool distance sensor 132 and one or more distance sensors 130 may indicate a distance between the guide bar and a body part wearing a corresponding one of the distance sensors 130. Of note, the tool distance sensor 132 may be a single sensor and / or include a set of such sensors.

[0017] As can be appreciated from the above description, the IMU-based sensor 120 may be a sensor configured to track movement in three dimensions. Meanwhile, the distance sensor 130 may be configured to measure or track distance in either two dimensions or simply one dimension (i.e., linear distance). In either case, a distance or proximity measurement may be performed such that the chainsaw 100 (or at least its cutting action) may be stopped based on a definable distance or proximity threshold (e.g., for short distances) or based on a combination of relative motion of the body part and the tool at an angular or linear velocity above a certain threshold (e.g., for longer distances, stopping with a distance based delay).

[0018] In an exemplary embodiment, the controller 140 may be located on a tool (e.g., the chainsaw 100), in which case it may be provided within a housing 150 of the chainsaw 100. The controller 140 may be configured to communicate with the tool position sensor 122 and / or the IMU-based sensor 120 to perform motion tracking, as described herein. In FIG. 1, the controller 140 and the tool position sensor 122 are shown collocated. However, such collocation is not required. Furthermore, the tool position sensor 122 may be located at any desired location on the chainsaw 100. Thus, for example, the controller 140 may have a wired or wireless connection to the tool position sensor 122. If communication between the IMU-based sensor 120 and the controller 140 occurs, such communication may be accomplished via wireless communication (e.g., short-range wireless communication technologies including Bluetooth, WiFi, Zigbee, etc.).

[0019] The controller 140 may also be in communication with the tool distance sensor 132. In this regard, for example, the tool distance sensor 132 may be configured to interact with the distance sensor 130 to perform distance measurements. The tool distance sensor 132 may then communicate with the controller 140 to provide distance measurements either continuously, periodically, or event-driven. At one end of the range, continuous distance measurements may be provided to and evaluated by the controller 140 at regular and frequent intervals. At the other end of the range, distance measurements may be provided only if the measured distance is below a threshold (e.g., minimum) distance. In either case, the controller 140 may be configured to evaluate the distance measurement in relation to initiating a warning or other protective function that the controller 140 may be configured to control. As an example, the chain brake 170 of the chain saw 100 may be activated if the distance measured for any one of the distance sensors 130 relative to the tool distance sensor 132 is less than the threshold distance. Alternatively or additionally, a warning may be provided (e.g., audibly, visually, or via tactile feedback). If hearing protection 180 is worn by operator 110, an audible warning may be provided via hearing protection 180. In some cases, a warning may be provided when a first (and longer distance) threshold is met, and chain brake 170 may be activated because a second (and shorter distance) threshold is met.

[0020] The same or different protection paradigms may also be initiated based on tracking performed using the IMU-based sensor 120 and the tool position sensor 122. Thus, for example, the controller 140 may be configured to evaluate inputs received from either (or both) of the IMU-based sensor 120 and the tool position sensor 122, as well as the distance sensor 130 and the tool distance sensor 132. The evaluation may be performed simultaneously or sequentially to provide a fusion of the motion tracking and distance measurement sensors (and functions). However, it should be understood that in some examples, a separate controller (e.g., separate instance of the controller 140) may also be employed for each one of the sets of wearable sensors. Furthermore, as discussed in more detail below, the controller 140 may be configured to prioritize the use of one or the other of motion tracking (e.g., via the IMU-based sensor 120 and the tool position sensor 122) and distance measurement (e.g., via the distance sensor 130 and the tool distance sensor 132) in certain circumstances. For example, distance measurement related measurements may be prioritized (or preceded) within a particular distance range (e.g., short distances) and motion tracking related measurements may be prioritized (or preceded) within another distance range (e.g., longer distances). Controller 140 may also be configured to manage the calibration of the motion tracking functions of IMU-based sensor 120 and tool position sensor 122.

[0021] The configuration of the controller 140 for performing sensor fusion and / or calibration according to an exemplary embodiment will now be described with reference to FIG. 2. In this regard, FIG. 2 illustrates a block diagram of the controller 140 according to an exemplary embodiment. As shown in FIG. 2, the controller 140 may include a processing circuit 200 of an exemplary embodiment as described herein. The processing circuit 200 may be configured to provide electronic control inputs to one or more functional units of the chain saw 100 (e.g., the chain brake 170) or the system (e.g., alerting the hearing protector 180), and to process data received at or generated by one or more of the motion tracking and distance measuring devices regarding various indications of travel or distance between the tool and the operator 110. Thus, the processing circuit 200 may be configured to perform data processing, control function implementation, and / or other processing and management services according to an exemplary embodiment.

[0022] In some embodiments, processing circuit 200 may be embodied as a chip or chipset. In other words, processing circuit 200 may comprise one or more physical packages (e.g., chips) that include materials, components, and / or wires on a structural assembly (e.g., substrate). The structural assembly may provide physical strength, size conservation, and / or electrical interaction limitations of the component circuits contained therein. Thus, processing circuit 200 may, in some cases, be configured to implement embodiments of the present invention on a single chip or as a single "system on a chip." Thus, in some cases, a chip or chipset may constitute a means for performing one or more operations to provide the functionality described herein.

[0023] In an exemplary embodiment, processing circuit 200 may include one or more instances of a processor 210 and memory 212 that may communicate with or otherwise control other components or modules that interact with processing circuit 200. As such, processing circuit 200 may be embodied as a circuit chip (e.g., an integrated circuit chip) configured to perform the operations described herein (e.g., using hardware, software, or a combination of hardware and software). In some embodiments, processing circuit 200 may be embodied as part of an on-board computer housed in housing 150 of chainsaw 100 to control operation of the system with respect to interaction with other motion tracking and / or distance measuring devices.

[0024] Although not required, some embodiments of the controller 140 may employ or communicate with a user interface 220. The user interface 220 may be in communication with the processing circuit 200 to receive indications of user input at the user interface 220 and / or provide audible, visual, tactile or other output to the operator 110. To this end, the user interface 220 may comprise, for example, a display, one or more switches, lights, buttons or keys, a speaker, and / or other input / output mechanisms. In an exemplary embodiment, the user interface 220 may comprise the hearing protectors 180 of FIG. 1, or one or more colored lights indicating status or other relatively basic information. However, in some cases, more complex interface mechanisms may be provided.

[0025] The controller 140 may employ or utilize components or circuitry that function as an equipment interface 230. The equipment interface 230 may comprise one or more interface mechanisms for enabling communication with other devices (e.g., the tool position sensor 122, the tool distance sensor 132, the chain brake 170, the hearing protection 180, the IMU-based sensor 120, and / or the distance sensor 130). In some cases, the equipment interface 230 may be any means, such as devices or circuitry embodied in either hardware or a combination of hardware and software, configured to transmit and receive data to and from components in communication with the processing circuit 200 via the internal communication system of the chainsaw 100 and / or via wireless communication devices (e.g., one-way or two-way wireless). Thus, the equipment interface 230 may include antennas and wireless devices for implementing Bluetooth, WiFi, or other short-range communications, or may include wired communication links for employing communications necessary to support the functionality described herein.

[0026] 2, the tool position sensor 122 and / or the IMU-based sensor 120 may be part of or embodied as a first sensor network 240, and the tool distance sensor 132 and / or the distance sensor 130 may be part of or embodied as a second sensor network 250. As such, the first and second sensor networks 240 and 250 may communicate with the controller 140 via the equipment interface 230. However, in some cases other direct connections or other indirect connections or communication mechanisms may be provided.

[0027] Processor 210 may be embodied in a number of different ways. For example, processor 210 may be embodied as one or more of a variety of processing means, such as a microprocessor or other processing element, a coprocessor, a controller, or a variety of other computing or processing devices comprising integrated circuits, such as, for example, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc. In an exemplary embodiment, processor 210 may be configured to execute instructions stored in memory 212 or otherwise accessible to processor 210. Thus, whether configured by hardware or a combination of hardware and software, processor 210 may represent an entity (e.g., physically embodied in a circuit - in the form of processing circuit 200) that, while appropriately configured, is capable of performing operations according to embodiments of the present invention. Thus, for example, when processor 210 is embodied as an ASIC, FPGA, etc., processor 210 may be hardware that is specifically configured to perform the operations described herein. Alternatively, as another example, if the processor 210 is embodied as an execution program of software instructions, the instructions may tangibly configure the processor 210 to perform the operations described herein.

[0028] In an exemplary embodiment, processor 210 (or processing circuitry 200) may embody, substantiate, or otherwise control the operation of controller 140 based on inputs received by processing circuitry 200. Thus, in some embodiments, processor 210 (or processing circuitry 200) may be considered to cause each of the operations described in connection with calibration module 260 and sensor fusion module 270. Each operation is caused in response to execution of instructions or algorithms that configure processor 210 (or processing circuitry 200) as appropriate to perform the corresponding function associated with each operation.

[0029] In an exemplary embodiment, the memory 212 may include one or more non-transitory memory devices, such as, for example, volatile and / or non-volatile memory, which may be either fixed or removable. The memory 212 may be configured to store information, data, applications, instructions, etc., to enable the processing circuit 200 to perform various functions according to an exemplary embodiment of the present invention. For example, the memory 212 may be configured to buffer input data for processing by the processor 210. Additionally or alternatively, the memory 212 may be configured to store instructions for execution by the processor 210. As yet another alternative or additional capability, the memory 212 may include one or more databases, which may store various data sets. Among the contents of the memory 212, applications may be stored for execution by the processor 210 to perform functions associated with each individual application. In some cases, the applications may include instructions for motion tracking and distance measurement as described herein, along with calibration and sensor fusion functions.

[0030] A calibration function may be performed by the calibration module 260. In this example, the calibration may be applicable only to the first sensor network 240 (i.e., motion tracking). However, calibration of other functions may be performed in addition, alternatively, or in addition. The calibration module 260 may be configured to interact with a zero relative velocity detection (ZRVD) sensor 280 (directly or via the device interface 230) located on the chainsaw 100 to facilitate calibration of the motion tracking device (i.e., the IMU-based sensor 120 and the tool position sensor 122). In this regard, the ZRVD sensor 280 may include a tactile sensor located on the handle (e.g., the front handle and the rear handle) of the chainsaw 100, an accelerometer and / or magnetometer input from the chainsaw 100 (e.g., associated with the tool position sensor 122), and a sensor on the trigger of the chainsaw 100. Input from the ZRVD sensor 280 may be integrated with input from the IMU-based sensor 120 and used to calibrate the motion tracking algorithms employed by the controller 140. In this regard, for example, the calibration process may include resetting velocity and movement errors introduced from the IMU-based sensor 120 that may accumulate over time.

[0031] In an exemplary embodiment, the ZRVD sensor 280 may be used to define (or learn) one or more specific tool and / or body positions (or combinations thereof) that correlate with a calibration position. In this regard, for example, certain positions may have known sensor data associated with them. Thus, the chainsaw 100 may be detected as being held in one or more of such positions during a calibration procedure in order to reset the portion of the sensor data to a known state. Where multiple positions may exist, various different portions of the sensor data may be reset until a complete reset is achieved by going through the entire sequence of calibration positions.

[0032] Thus, the user or maintenance manual for the chainsaw 100 may list the calibration positions. A calibration mode may be entered and the corresponding positions may be cycled through in order. The calibrated positions may possibly relate to both the chainsaw 100 and the operator 110. Thus, for example, the operator 110 (who may be a maintenance technician or in various cases the owner) may be guided according to an assumed posture in which the chainsaw 100 is held while wearing the IMU-based sensor 120. The position may also or alternatively be sensed by a tactile sensor that may be part of the ZRVD sensor 280. Thus, for example, the ZRVD sensor 280 may detect that the operator 110 has operated the chainsaw 100 into one of the calibration positions based on how the operator 110 holds the chainsaw 100 and / or based on trigger presses and correlated accelerometer and / or magnetometer readings to determine the vertical or horizontal orientation of the chainsaw 100. In some cases, the inclusion of multiple sensors, the IMU-based sensor 120 and the sensors on the chainsaw 100 (e.g., the ZRVD sensor 280), may ensure sufficient independence to achieve good results. Thus, if the chainsaw 100 can be detected to be in various positions, the calibration can be performed automatically when one of the calibrated positions is detected (i.e., not in response to an induced position, but in response to detection of an assumed position while holding the chainsaw 100 during use). Detection of the position (and in particular the calibrated position) may occur when the operator 110 pulls the trigger (or activates another button or actuation member of the chainsaw 100). In some cases, a tactile pressure sensor in the handle of the chainsaw 100 (as determined by the ZRVD sensor 280) may be used to determine the position of the hand versus determining the current position of the operator 110 and / or the position of the chainsaw 100.

[0033] In some cases, the calibration procedure may be part of routine maintenance at a prescribed interval. However, the calibration procedure may also be performed automatically whenever a calibrated position is detected (either every time or if a calibration at the corresponding calibrated position has not been performed within a given threshold period). The calibration algorithm may be configured to perform double integration of the linear movement acceleration, the orientation gyro data, and Kalman filtering to improve prediction of the motion tracking with error correction.

[0034] FIG. 3 shows a schematic diagram of the calibration position of the exemplary embodiment. As shown in FIG. 3, the chain saw 100 may be detected as being held in a specific posture by an operator having an IMU-based sensor 120 at a known location (based on a specific posture). In some cases, the IMU-based sensor 120 may be fixed to (e.g., mounted within) a fixed or known location on a PPE, such as a jacket or leg wrap. In this example, the IMU-based sensor 120 includes a left glove sensor 121 and a left elbow sensor 123, a right glove sensor 125, and a right elbow sensor 127. However, it should be understood that other sensors in other locations may also be included. Thus, the locations and specific sensors shown are provided merely to facilitate the description of the exemplary embodiment and are not intended to limit the exemplary embodiment.

[0035] As can be seen from FIG. 3, a distance 300 from the end of the bar of the chain saw 100 to the left glove sensor 121, which may be known to be on the front handle of the chain saw 100, may be known. As mentioned above, one or more tactile sensors 310 (e.g., as part of the ZRVD sensor 280) may be located on the front handle to ascertain a specific location of the operator's left hand (and / or the left glove sensor 121). A distance 320 from the left glove sensor 121 to the left elbow sensor 123 may also be known for a specifically designated position. In the same manner, one or more tactile sensors 330 (again, an example of the ZRVD sensor 280) may be located on the rear handle of the chain saw 100. The tactile sensor 330 may ascertain a specific location of the operator's right hand (and / or the right glove sensor 125). Meanwhile, a distance 340 from the right glove sensor 125 to the right elbow sensor 127 may also be known for a specifically designated position. The distance 350 from the end of the bar of the chainsaw 100 to the right glove sensor 125 and the distance 360 ​​between the tactile sensors 310 and 330 may also be known, so the IMU-based sensor 120 can be calibrated using stored reference data associated with the known distances (300, 320, 340, 350 and 360) and poses.

[0036] FIG. 4 is a block diagram of a calibration method according to an exemplary embodiment. As shown in FIG. 4, reference data may be collected for one or more attitudes in operation 400. The reference data may include information related to roll, pitch, yaw, and other variables of interest including attitude acceleration and velocity information including motion. In operation 410, the operator 110 may be guided through each of the one or more attitudes or the operator 110 may be sensed / detected in any of the one or more attitudes to obtain current data for comparison with the reference data. Then, in operation 420, the controller 140 may reset errors associated with the IMU-based sensor 120 based on the comparison for any or all applicable attitudes.

[0037] As noted above, in some cases, the defined variables may vary depending on the particular implementation (e.g., X / Y / Z, roll / pitch / yaw, Euler, quaternion, etc.). Other variables may include global data structure variables including acceleration, velocity, angular velocity, position, gyro indication values, etc. that may be used for device state and / or sensor fusion (e.g., by sensor fusion module 270). Based on the distances, various local variables such as calculated movement (CalcDis), calculated orientation (CalcOri), calculated velocity (CalcVel), etc. may be measured or determined. As an example of a calculation for calibrated motion tracking, the following calculation may serve as one example program that may be employed. State:=Init() / / For start, orientation, combine a measurement position matrix based on known hand positions on the steering wheel with accelerometer and magnetometer readings, and augment the initial state at the reported position with machine learning (ML) based training set data. / / Loop While(On) Calculate() Function Calculate()( MeasUpdate(State) / / Similar to Init, but state-adapted measurements, i.e. bias parameters updated continuously at each step. / / / / The following calculations use the updated parameters from the MeasUpdate step / / CalcVel:=∫(acceleration) / / Calculated velocity / / CalcDis:=Initial Movement + ∫(CalcVel) / / Calculated Movement / / CalcOri:=Initial direction + ∫(angular velocity) / / Calculated direction / / Est:=Update(CalcDis, CalcOri) / / Continuously calculated state / / ) Function MeasUpdate()( Complex functions that implement the update bias parameters for states, actions, and observations (e.g., Kalman filter theory) )

[0038] The sensor fusion module 270 may be configured to fuse data received by the motion tracking devices (e.g., IMU-based sensor 120 and tool position sensor 122) and distance measurement devices (e.g., distance sensor 130 and tool distance sensor 132). Data received from the motion tracking devices may be received at the controller 140 and processed to determine motion tracking information. The motion tracking information may then be provided to the sensor fusion module 270. Thus, the motion tracking information from the motion tracking devices, when calibrated, may be considered to be ZRVD calibrated IMU motion tracking information.

[0039] Data received from the distance measurement device may also be received at the controller 140 (either at the same instance or at a different instance of the controller 140) and processed to determine distance measurement information. As described below with reference to the description of Figures 5 and 6, the processing to determine distance measurement information may take a number of different forms. Regardless of the form, the distance measurement information may then be provided to the sensor fusion module 270. The sensor fusion module 270 may be configured to process the distance measurement information and the motion tracking information based on a set of fusion rules. The fusion rules may be created based on the understanding that the distance measurement information may be more accurate for close distances, and the motion tracking information may be most useful for tracking motion when the chainsaw bar is relatively far from any body part. Thus, the fusion rules may define a hierarchy of priorities for the distance measurement information and the motion tracking information based on proximity. For example, if movement to a body part is detected, as the distance decreases, the authority of the distance measurement information will increase, and as the distance increases, the authority of the motion tracking information regarding the determination of the protection features (if any) will increase.

[0040] FIG. 5 is a block diagram showing an example of a fusion rule that can be applied according to an exemplary embodiment. In the context of FIG. 5, the following definitions of terms apply. Dist: The distance between the chain 102 and the body part. Motion: The motion of the chainsaw bar (aggregated based on, for example, the inputs of an accelerometer and a gyro). Dir: The direction of the motion of the chainsaw bar based on the calculated state. In this context, the first rule 500 may be defined with respect to the minimum distance allowed for the stationary bar. According to the first rule 500, if Dist < X1, then StopChain (chain stop). In other words, if the bar is closer than the minimum distance (X1), the chain 102 needs to be stopped. The second rule 510 may be defined with respect to the minimum distance allowed during high-speed motion. According to the second rule 510, if (Motion > Y1, Dir = bodypart (body part) and dist < X2), then StopChain. In other words, if the bar is moving beyond a certain speed (Y1) and the distance to the body part is less than the minimum distance (X2) when motion towards any sensor is detected, the chain 102 needs to be stopped. The third rule 520 may be defined with respect to the maximum allowable motion speed regardless of the distance. According to the third rule 520, if (Motion > Y2 and Dir = bodypart), then StopChain. In other words, if the bar is moving beyond a certain speed (Y2) when motion towards any body part is detected, the chain 102 needs to be stopped regardless of the current distance. The fourth rule 530 may be defined with respect to the maximum allowable motion speed regardless of the direction. According to the fourth rule 530, if (Motion > Y3), then StopChain. In other words, if the bar is moving beyond a certain speed (Y3), the chain 102 needs to be stopped regardless of the current distance or the direction of movement of the bar. This is only an example of a set of rules that can be adopted.

[0041] As noted above, distance measurement information can take multiple forms based on the particular sensor and technology used to implement the distance measurement device. In an exemplary embodiment, reader-based measurements may be employed in some cases. For example, the tool distance sensor 132 may be embodied as an electromagnetic reader (or transponder) attached to the tool (e.g., in close proximity to the working assembly, i.e., in this case, the chain 102 of the chainsaw 100, such as on the guide bar) and may have a main lobe that covers the entire circumference of the working assembly (e.g., the guide bar and chain 102) of the tool. The electromagnetic reader may be configured to sense devices (e.g., electronic tags) using backscatter principles. A radio frequency identification (RFID) tag is one example of such a tag. However, in some cases the tag may be active. In any case, FIG. 6 illustrates an exemplary reader 600 with an electronic tag 610 to facilitate further description of such examples.

[0042] Referring to FIG. 6, the reader 600 may utilize the power provided by the chainsaw 100 to implement an adaptive transmission power algorithm as part of the range determination process. The adaptive transmission power algorithm may include generating an initial detection signal 620 for transmission in a modulated code over a carrier wave by increasing the transmission power until detection occurs. If the tag 610 is within a specified distance from the reader 600 and the power level is sufficient, the tag 610 will receive enough power from the transmitted initial detection signal 620 to generate a response 630 that is subsequently detected by the reader 600. The response 630 retransmits a code to the response unit 600 that is used as an identifier for the tag 610 to identify the tag 610. After detecting the tag 610, the response unit 600 may then reduce the transmission power from the response unit 600 and transmit a power reduction signal 640 having a gradually decreasing value than the initial detection signal 620. If received with sufficient power, the tag 610 will transmit a power reduction response 650. The reader 600 will then reduce the power again (e.g., gradually) and repeat the progressive power reduction until no response is received from the tag 610. The signal associated with the last (i.e., lowest) power transmitted when tag 610 is no longer detected may be referred to as distance marker signal 660. When the power of distance marker signal 660 is determined, it is found to be proportional to distance in a fairly consistent and accurate manner.

[0043] In this regard, the detection range is approximately exponentially proportional to the output or transmitted power of the reader 600. Although the specific values ​​may vary from antenna to antenna (e.g., from reader to reader), the proportionality is fairly consistent. Thus, an accurate mapping of power to detection range may be achieved, and small calibration adjustments may be made to individual antennas. In some cases, other correction factors (e.g., temperature) may also be applicable. The mapping may be stored in memory 212 and may be accessible to the controller 140 to determine the distance measurement information. Thus, once the distance marker signal 660 is determined, the above process may be repeated (as indicated by operation 670) to determine additional instances of the distance marker signal 660. Any desired number of iterations may be completed, and convergence around the range of powers where the tag 610 is not used may be determined. For example, an average or mean power for the distance marker signal may be calculated using each or a predetermined number of iterations of operation 670. The average or mean dynamics for the distance marker signals may then be correlated to the mapping stored in memory to determine the range or distance between the corresponding sensor (i.e., tag 610) and the reader 600. This process can be rapidly repeated and cycled for each of the distance sensors 130 using a time-multiplexed approach.

[0044] An example of pseudocode that may be used for simplified range detection is shown below: In this context, the following terminology definitions apply: INT POW := 0 / / Output power variable / / INT A:=5 / / Output power increment / / BOOL SENSE:=False / / Continuously updated tag sense variable INT RANGE:=500 / / Range variable Loop ( SENSE := update () / / Sensing function (function?) / / If SENSE=false, POW=POW+A Other POW:=POW-A RANGE:=MAP / / Maps power from a table function or transfer function to a range / / )

[0045] Instead of using the above reader 600 and tag 610 paradigm, a time-of-flight based measurement may be used in some cases. In this regard, distance measurement information may be calculated from the time-of-flight of a transmitted signal if the speed of the signal is known. In the case of electromagnetic signals (e.g., laser, infrared, radio frequency), the speed is known to be the speed of light. In an example where the tool distance sensor 132 is embodied as a laser or infrared light source, the tool distance sensor 132 generally transmits a laser or infrared light and then measures the time it takes to receive a reflection from one (or more) of the distance sensors 130. In the case of a voice or audible signal, the speed is known to be the speed of sound, and the distance sensor 130 may be a transmitter such that the tool distance sensor 132 measures the time-of-flight in one direction only. In some cases, a wireless transceiver may be preferred to avoid issues related to the possibility of dirt or other objects blocking or fouling the sensor. In such an example, the response time (i.e., the time-of-flight in both directions) may be measured by the tool distance sensor 132 (acting as a master transceiver).

[0046] In any case, for short distance applications, which generally apply to the situations in which the exemplary embodiments operate, the time of flight is in the range of a few nanoseconds for light and radio waves, necessitating a relatively high sampling rate to achieve good accuracy. For this reason, in some embodiments, ultrasonic transmitters and receivers (i.e., active, not passive, ultrasonic) may be employed, since sound travels much slower. Slow wave travel may allow a lower sampling frequency to be employed while still achieving good accuracy.

[0047] As yet another alternative for obtaining distance measurement information, radar-based measurements may be employed. In this regard, for example, a millimeter wave radar may be employed to provide good accuracy within the range of 0-500 mm (which is typical in this context) along with resistance to both dirt and moisture. Millimeter wave radar is also relatively fast and lenses can be added to control the radar beam. Besides this, advanced signal processing techniques can be employed to distinguish various objects from one another. In such an example, the tool distance sensor 132 may be embodied as a millimeter wave radar sensor configured to detect the distance sensor 130 based on replies received in response to each transmission.

[0048] Thus, in one exemplary embodiment, a system for protecting an operator of a power tool may be provided. The system may include a first set of wearable sensors worn by the operator, a second set of wearable sensors worn by the operator, a first tool sensor disposed on the power tool where the first tool sensor is configured to communicate with the first set of wearable sensors, a second tool sensor disposed on the power tool where the second tool sensor is configured to communicate with the second set of wearable sensors, and a controller. The controller may be configured to determine whether to initiate a protective action on the power tool based on a distance between the first tool sensor and the first set of wearable sensors and a distance between the second tool sensor and the second set of wearable sensors.

[0049] In some cases, modifications or amplifications may be further employed as optional alterations or enhancements to the above description. Such modifications or enhancements may be implemented mutually exclusive or in any combination with each other. In some cases, such modifications or amplifications include: (1) the power tool may be a chain saw, and the protective action may be to activate a chain brake of the chain saw when one of the first set of wearable sensors or the second set of wearable sensors is within a threshold distance of a respective one of the first tool sensor or the second tool sensor. In an exemplary embodiment, (2) the power tool may be a chain saw or other power equipment such as a power cutter with a blade or chain, and the protective action may be to provide an audio or visual warning to an operator when one of the first set of wearable sensors or the second set of wearable sensors is within a threshold distance of a respective one of the first tool sensor or the second tool sensor. In some cases, (3) the first set of wearable sensors may include a plurality of inertial measurement unit (IMU) based sensors, and the first tool sensor may be a tool position sensor. In such an example, the second set of wearable sensors may include a plurality of distance sensors, and the second tool sensor may be a reader disposed on the power tool. In some embodiments, (4) the IMU-based sensor and the tool position sensor may be periodically calibrated based on predefined poses of the operator and corresponding positions of the power tool. In an exemplary embodiment, (5) the controller may be configured to store reference data at each of the predefined poses corresponding to known distances from each of the IMU-based sensors to the tool position sensor. In such an example, the controller may be configured to perform a comparison between the reference data and current data collected at the predefined poses and reset an error associated with the IMU-based sensor based on the comparison. In some embodiments, (6) the controller may be configured to obtain distance information from the plurality of distance sensors and readers and obtain motion tracking information from the IMU-based sensor and the tool position sensor.In such an example, the controller may be configured to prioritize distance information over motion tracking information within a predefined distance and prioritize motion tracking information over distance information outside the predefined distance. In some cases, (7) the transponder may be a millimeter wave radar sensor with a focusing lens for the beam. In an exemplary embodiment, (8) the reader may be an optical or ultrasonic transmitter, and the controller may be configured to calculate distance information based on a time-of-flight measurement associated with the reader and the plurality of distance sensors. In some cases, (9) the reader may be an electromagnetic reader configured to detect an electronic tag, and each of the plurality of distance sensors may be an electronic tag. In some embodiments, (10) the controller may be configured to perform the steps of: a) increasing the transmission power until an instance of the electronic tag is detected; b) decreasing the power until an instance of the electronic tag is not detected; c) repeating steps a) and b) to determine an average or mean power at which the electronic tag is not detected; and d) determining a range between the reader and the instance of the electronic tag based on the average or mean power.

[0050] In an exemplary embodiment, any, any, or all of the modifications / amplifications (1)-(10) may be employed in any combination with one another. Additionally, in some cases, the system may include any of the first set of wearable sensors in which the sensors are configured to be calibrated (e.g., as in (4) and (5) above). In some cases, the system may include only the second set of wearable sensors, where the sensors are configured as in (10) above.

[0051] Many modifications and other embodiments of the inventions described herein will come to mind to one skilled in the art to which such inventions pertain having the benefit of the teachings presented in the foregoing description and the associated drawings. It is to be understood, therefore, that the invention is not limited to the particular embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, while the foregoing description and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and / or features, different combinations of elements and / or features may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, it is contemplated that other combinations of elements and / or features than those explicitly described above may be set forth in some of the appended claims. Where advantages, benefits or solutions to a problem are described herein, it is to be understood that such advantages, benefits and / or solutions may be applicable to some, but not necessarily all, exemplary embodiments. Thus, any advantages, benefits or solutions described herein should not be construed as critical, necessary or essential to every embodiment or claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. 1. A system for protecting an operator (110) of a power tool, the system comprising: a first set of wearable sensors (120) worn by the operator (110); a second set of wearable sensors (130) worn by the operator (110); a first tool sensor (122) disposed on the power tool, the first tool sensor (122) configured to communicate with the first set of wearable sensors (120); a second tool sensor (132) disposed on the power tool, the second tool sensor (132) configured to communicate with the second set of wearable sensors (130); a controller (140) configured to determine whether to initiate a protective action on the power tool based on a distance between the first tool sensor (122) and the first set of wearable sensors (120) and a distance between the second tool sensor (132) and the second set of wearable sensors (130).

2. 2. The system of claim 1, wherein the power tool is a chainsaw (100) or other power equipment such as a power cutter having a blade or chain (102), and the protective action includes activating a chain brake (170) of the chainsaw (100) when one of the first set of wearable sensors (120) or the second set of wearable sensors (130) is within a threshold distance of a respective one of the first tool sensor (122) or the second tool sensor (132), or when a speed of the power tool relative to the body of the operator (110) exceeds a threshold speed, or when an acceleration of the power tool relative to the body of the operator (110) exceeds a threshold acceleration.

3. 2. The system of claim 1, wherein the power tool is a chainsaw (100) or other power equipment such as a power cutter with a blade or chain (102), and the protective action includes providing an audible or visual warning to the operator (110) when one of the first set of wearable sensors (120) or the second set of wearable sensors (130) is within a threshold distance of a respective one of the first tool sensor (122) or the second tool sensor (132).

4. the first set of wearable sensors (120) includes a plurality of inertial measurement unit (IMU) based sensors (120), and the first tool sensor (122) includes a tool position sensor (122); 2. The system of claim 1, wherein the second set of wearable sensors (130) includes a plurality of distance sensors (130) and the second tool sensor (132) includes a reader (132) disposed on the power tool.

5. 5. The system of claim 4, wherein the IMU-based sensor (120) and the tool position sensor (122) are periodically calibrated based on a predefined pose of the operator (110) and a corresponding position of the power tool.

6. the controller (140) stores reference data corresponding to known distances from each of the IMU-based sensors (120) to the tool position sensor (122) at each of the predefined poses (400); the controller (140) is configured to perform a comparison between the reference data and current data collected at the predefined pose (410); The system of claim 5 , wherein the controller (140) is configured to reset an error associated with the IMU-based sensor (120) based on the comparison (420).

7. the controller (140) is configured to obtain distance information from the plurality of distance sensors (130) and the reader (132) and to obtain motion tracking information from the IMU-based sensor (120) and the tool position sensor (122); 5. The system of claim 4, wherein the controller is configured to prioritize the distance information over the motion tracking information within a predefined distance and to prioritize the motion tracking information over the distance information outside the predefined distance.

8. The system of claim 4 , wherein the reader (132) is a millimeter wave radar sensor with or without a radar beam lens.

9. the reader (132) being a radio transmitter, an optical transmitter or an ultrasonic transmitter; The system of claim 4 , wherein the controller (140) is configured to calculate distance information based on time-of-flight measurements associated with the reader (132) and the plurality of distance sensors (130).

10. The reader (132) is an electromagnetic radio reader (600) configured to detect an electronic tag (610); The system of claim 4 , wherein each of the plurality of distance sensors (130) is an electronic tag (610).

11. The controller (140) a) increasing a transmitted power until an instance of said electronic tag (610) is detected; b) reducing power until said instance of said electronic tag (610) is no longer detected; c) repeating steps a) and b) to determine the mean or average dynamics at which the electronic tag (610) becomes undetectable; 11. The system of claim 10, configured to perform the steps of: d) determining the range between the reader (600) and the instance of the electronic tag (610) based on the mean or average dynamics.

12. A system for protecting an operator (110) of a power tool, the power tool being a chain saw (100) or other power equipment such as a power cutter equipped with a blade or chain (102), the system comprising: a plurality of inertial measurement unit (IMU) based sensors (120) worn by the operator (110); a tool position sensor (122) disposed on the power tool; a controller (140) configured to determine whether to initiate a protective action on the power tool based on measurements between the IMU-based sensor (120) and the tool position sensor (122), The IMU-based sensor (120) and the tool position sensor (122) are periodically calibrated based on a predefined pose of the operator (110) and a corresponding position of the power tool.

13. the controller (140) stores reference data corresponding to known distances from each of the IMU-based sensors (120) to the tool position sensor (122) at each of the predefined poses (400); the controller (140) is configured to perform a comparison between the reference data and current data collected at the predefined pose (410); The system of claim 12 , wherein the controller (140) is configured to reset an error associated with the IMU-based sensor (120) based on the comparison (420).

14. The system of claim 13, further comprising a plurality of distance sensors (130) also worn by the operator and a reader (132) disposed on the power tool.

15. the controller (140) is configured to obtain distance information from the plurality of distance sensors (130) and the reader (132) and to obtain motion tracking information from the IMU-based sensor (120) and the tool position sensor (122); 15. The system of claim 14, wherein the controller (140) is configured to prioritize the distance information over the motion tracking information within a predefined distance and to prioritize the motion tracking information over the distance information outside the predefined distance.

16. The power tool is a chain saw (100) or other power device such as a power cutter equipped with a blade or chain (102); and / or the protective action includes activating a chain brake (170) of the chain saw (100) when one of the first set of wearable sensors (120) or the second set of wearable sensors (130) is within a threshold distance of a respective one of the first tool sensor (122) or the second tool sensor (132); and / or 13. The system of claim 12, wherein the protective action includes providing an audible or visual warning to the operator (110) when one of the first set of wearable sensors (120) or the second set of wearable sensors (130) is within the threshold distance of a respective one of the first tool sensors (122) or the second tool sensors (132), or when the speed of the power tool relative to the body of the operator (110) exceeds a threshold speed, or when the acceleration of the power tool relative to the body of the operator (110) exceeds a threshold acceleration.

17. A system for protecting an operator (110) of a power tool, the power tool being a chain saw (100) or other power equipment such as a power cutter having a blade or chain (102), the system comprising: A plurality of distance sensors (130) worn by the operator (110); A reader (132) disposed on the power tool; a controller (140) configured to determine whether to initiate a protective action on the power tool based on a distance between each of the distance sensors (130) and the reader (132), The controller (140) is configured to implement an adaptive power control cycle to determine the distance between each of the distance sensors (130) and the reader (132).

18. Each of the distance sensors (130) is an electronic tag (610); The adaptive power control cycle comprises: a) increasing a transmitted power until an instance of said electronic tag (610) is detected; b) reducing power until said instance of said electronic tag (610) is no longer detected; c) repeating steps a) and b) to determine the mean or average dynamics at which the electronic tag (610) becomes undetectable; 20. The system of claim 17, further comprising: d) determining a range between said reader (600) and said instance of said electronic tag (610) based on said mean or average dynamics.

19. The power tool is a chain saw (100) or other power equipment such as a power cutter with a blade or chain (102); the protective action includes activating a chain brake (170) of the chain saw (100) when one of the first set of wearable sensors (120) or the second set of wearable sensors (130) is within a threshold distance of a respective one of the first tool sensors (122) or the second tool sensors (132), or when a speed of the power tool relative to the body of the operator (110) exceeds a threshold speed, or when an acceleration of the power tool relative to the body of the operator (110) exceeds a threshold acceleration; and / or 20. The system of claim 18, wherein the protective action includes providing an audible or visual warning to the operator (110) when one of the first set of wearable sensors (120) or the second set of wearable sensors (130) is within a threshold distance of a respective one of the first tool sensor (122) or the second tool sensor (132).

20. 20. The system of claim 18, further comprising a plurality of inertial measurement unit (IMU) based sensors (120) worn by the operator (110) and a tool position sensor (122) disposed on the power tool, The system, wherein the controller (140) is configured to determine whether to initiate the protective action on the power tool based on measurements between the IMU-based sensor (120) and the tool position sensor (122).

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