WO2024099929A1

WO2024099929A1 - System for protecting an operator of a power tool using time-of-flight sensors

Info

Publication number: WO2024099929A1
Application number: PCT/EP2023/080768
Authority: WO
Inventors: Guoliang Wang; Niklas SARIUS; Per NORÉN; Sören KAHL
Original assignee: Husqvarna Ab
Priority date: 2022-11-07
Filing date: 2023-11-06
Publication date: 2024-05-16

Abstract

A power tool (200) may include a working assembly (220) to perform a cutting operation, a powerhead to power the working assembly (220), a housing (270) operably coupled to the working assembly (220) which contains the powerhead, and a protection assembly. The protection assembly may include a sensor array (210) disposed at the power tool (200), and a controller (140) which may include processing circuitry (280) configured to determine whether to initiate a protective action with respect to the power tool (200). The sensor array (210) may define a field of view (230) that may surround a working assembly (220) of the power tool (200). The field of view (230) may include a protective zone (260). The controller (140) may process data from the sensor array (210) to determine when a trigger event may occur while the power tool (200) may be in operation. The sensor array (210) may include a time-of-flight sensor disposed on a front face of the power tool (200), proximate to the working assembly (220).

Description

SYSTEM FOR PROTECTING AN OPERATOR OF A POWER TOOL USING TIME-OF-

FLIGHT SENSORS

TECHNICAL FIELD

[0001] Example embodiments generally relate to power equipment and, more particularly, relate to a system configured to protect the user of a chainsaw or other power equipment such as power cutters with blade or chain.

BACKGROUND

[0002] Property maintenance tasks are commonly performed using various tools and/or machines that are configured for the performance of corresponding specific tasks. Some of those tools, like chainsaws, are designed to be effective at cutting trees in situations that could be relatively brief, or could take a long time including, in some cases, a full day of work. When operating a chainsaw for a long period of time, fatigue can play a role in safe operation of the device. However, regardless of how long the operator uses the device, it is important that the operator remain vigilant to implementing safe operating procedures in order to avoid injury to himself/herself and to others.

[0003] To help improve safety, operators are encouraged to wear protective clothing and other personal protective equipment (PPE). Although wearing of PPE is always recommended while operating power equipment, some operators may nevertheless not do so. Accordingly, it may be desirable to define additional “intelligent” protection solutions that do not rely on the present type of PPE in order to protect users of chainsaws and other outdoor power equipment.

BRIEF SUMMARY OF SOME EXAMPLES

[0004] Some example embodiments may provide a protection assembly for a power tool. The protection assembly may include a sensor array disposed at the power tool, and a controller which may include processing circuitry configured to determine whether to initiate a protective action with respect to the power tool. The sensor array may define a field of view that may surround a working assembly of the power tool. The field of view may include a protective zone. The controller may process data from the sensor array to determine when a trigger event may occur while the power tool may be in operation. The sensor array may include a time-of-flight sensor disposed on a front face of the power tool, proximate to the working assembly.

[0005] Some example embodiments may provide for a power tool. The power tool may include a working assembly which may perform a cutting operation, a powerhead which may power the working assembly, a housing which may be operably coupled to the working assembly and may contain the powerhead, and a protection assembly. The protection assembly may include a sensor array disposed at the power tool, and a controller which may include processing circuitry configured to determine whether to initiate a protective action with respect to the power tool. The sensor array may define a field of view that may surround a working assembly of the power tool. The field of view may include a protective zone. The controller may process data from the sensor array to determine when a trigger event may occur while the power tool may be in operation. The sensor array may include a time-of-flight sensor disposed on a front face of the power tool, proximate to the working assembly.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) [0006] Having thus described some example embodiments in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0007] FIG. 1 illustrates a concept diagram of a system in which wearable sensors may operate in accordance with an example embodiment;

[0008] FIG. 2 illustrates a profile view of a power tool with a protection assembly according to an example embodiment;

[0009] FIG. 3 illustrates the power tool with the protection assembly in accordance with an example embodiment;

[0010] FIG. 4 illustrates the power tool with the protection assembly in accordance with an example embodiment;

[0011] FIG. 5 illustrates the power tool with the protection assembly in accordance with an example embodiment;

[0012] FIG. 6 illustrates the power tool with the protection assembly in accordance with an example embodiment; and [0013] FIG. 7 illustrates a block diagram of the protection assembly in accordance with an example embodiment.

DETAILED DESCRIPTION

[0014] Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. Furthermore, as used herein, the term “or” is to be interpreted as a logical operator that results in true whenever one or more of its operands are true. As used herein, operable coupling should be understood to relate to direct or indirect connection that, in either case, enables functional interconnection or interaction of components that are operably coupled to each other.

[0015] FIG. 1 illustrates a protection assembly of an example embodiment being applied where the power tool is a chainsaw 100 having a working assembly that may include an endless chain 102 that rotates about a guide bar to perform cutting operations. As shown in FIG. 1, an operator 110 wears wearable sensors. In this regard, the operator 110 is wearing a helmet 112, gloves 114, and boots 116 as examples of PPE. The sensors may be integrated into the PPE, or may be attached thereto. Of course, the sensors could alternatively be integrated into or attached to other clothing or gear, and at other locations as well. Thus, the specific examples of the protection assembly shown in FIG. 1 should be appreciated as being non-limiting in relation to the numbers of sensors, locations of the sensors, and methods of attaching the sensors to the operator 110 and/or the gear of the operator 110.

[0016] In this example, the wearable sensors of the protection assembly may include IMU- based sensors 120. The IMU-based sensors 120 of FIG. 1 may be disposed on the helmet 112, gloves 114 and boots 116 that the operator 110 is wearing, but could be at other locations as well, as noted above. Thus, for example, additional IMU-based sensors 120 could be provided at the knees, elbows, chest or other desirable locations on the operator 110. The IMU-based sensors 120 may operate in cooperation with a tool position sensor 122, which may be disposed at the working assembly of the power tool (e.g., chainsaw 100). Of note, the tool position sensor 122 may itself be an IMU-based sensor and/or may 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 in order to enable relative positions between body parts at which the IMU-based sensors 120 are located and the tool to be tracked. In some embodiments, the IMU- based sensors 120 may include a magnetometer. In this regard, the IMU-based sensors 120 may also collect data relative to the magnetic fields detected around the operator 110. The data from the magnetometers may be considered in addition to data from the tool position sensor 122 when performing motion tracking. The motion tracking may be performed in connection with the application of motion tracking algorithms on linear acceleration and angular velocity data in three dimensions.

[0017] While FIG. 1 illustrates a specific view of a protection assembly for the chainsaw 100 in which sensors worn by the operator 110 are employed, there are many situations in which operators may not wear PPE or, even if wearing PPE, may not wear PPE that includes the sensors described above. In such cases, additional technology may be implemented independent of the clothing (or sensors) that are worn by the operator 110. FIGS. 2-6 illustrate a general view of an example embodiment of a power tool 200 including a protection assembly that does not rely on operator- worn sensors, some components of which may or may not have been described above in reference to the specific chainsaw 100. Accordingly, FIG. 2 illustrates a power tool 200 that may include a working assembly 220 which may perform a cutting operation, a powerhead which may power the working assembly 220, a housing 270 which may be operably coupled to the working assembly 220 and may contain the powerhead, and a protection assembly. In some embodiments, the power tool 200 may be a chainsaw 100. In this regard, the working assembly 220 may include a cutting chain, and a guide bar about which the chain rotates. In some other embodiments, the power tool 200 may be power cutters. In this regard, the working assembly 220 may include a cutting blade. The protection assembly may include a sensor array 210 disposed on the housing 270 of the power tool 200. The sensor array 210 may include a plurality of sensors that may provide an alternative form of distance tracking and/or object recognition for the protection assembly.

[0018] Although the sensor array 210 of this example is shown to be disposed between a working assembly 220 and a handle 205 of the power tool 200, such orientation is not necessary. In this regard, the sensor array 210 may be split into separate portions and disposed on opposing sides of the working assembly 220. In other cases, the sensor array 210 may be disposed at any location on the power tool 200 that may provide an unobstructed view of the working assembly 220, such as on a front face of the power tool 200 proximate to the working assembly 220. The sensor array 210 may define a field of view 230 that may entirely encompass the working assembly 220 of the power tool 200. In some cases, the sensor array 210 may be provided with the protection assembly and with or without the implementation of IMU-based sensors 120. [0019] FIG. 2 illustrates a profile view of the power tool 200 and sensor array 210 according to an example embodiment. As shown in FIG. 2, one such alternative form of distance tracking may be accomplished via time-of-flight (TOF) sensors and measurements. Time-of-flight measurements may rely on the known principles of waves (e.g. light waves, sound waves, or other electro-magnetic waves) to measure and obtain specific data from the field of view 230. The TOF measurement may begin with a TOF sensor generating a carrier wave 215. The carrier wave 215 may travel from its origin at the TOF sensor out away from the power tool 200 and into the field of view 230. The rate at which the carrier wave 215 travels (i.e., distance traveled per unit of time) may be known depending on a few parameters, such as the type of wave that the carrier wave 215 is, and certain properties of the medium that the carrier wave 215 may be traveling through. For example, if the carrier wave 215 is a light wave, the rate at which the carrier wave 215 travels is simply the speed of light.

[0020] In some cases, the carrier wave 215 may encounter an object within the field of view 230. In this regard, the carrier wave 215 may reflect off of the object, and back to the TOF sensor. The TOF sensor may therefore not only generate the carrier wave 215, but also detect when the carrier wave 215 returns to the TOF sensor. By detecting when the carrier wave 215 returns to the TOF sensor, the distance to the object that the carrier wave 215 reflects off of may be determined. In this regard, TOF measurements utilize a simple mathematical equation for determining the distance to the object:

Where d is the distance to the object, r is the rate of the carrier wave 215, and t is the time that elapsed between the carrier wave 215 leaving the TOF sensor and the carrier wave 215 returning to the TOF sensor after reflecting off of the object in the field of view 230. Thus, TOF sensors may record the time (t) that the carrier wave 215 takes to travel to, and back from, the object within the field of view 230. In some embodiments, the TOF sensors may also record other parameters associated with the reflectivity of the object (e.g. reflected signal strength). In this regard, the reflectivity of the object may be determined from the strength of the carrier wave 215 that returns to the TOF sensor after reflecting off of the object. For example, if the carrier wave 215 is a light wave, the strength of the returning carrier wave 215 of the light wave may be the amplitude of the carrier wave 215. Due to the laws of the conservation of energy, the amplitude of the reflected carrier wave 215 will always be smaller than the amplitude of the initial carrier wave 215. This is true because the amplitude is a measure of energy of the carrier wave 215, and the carrier wave 215 must lose some energy to the object off of which it reflects. In other words, the carrier wave 215 will return to the TOF sensor with a reduced amplitude. As such, a more reflective surface may return the carrier wave 215 to the TOF sensor with minimal reduction in the amplitude of the carrier wave 215 while a less reflective surface may return the carrier wave 215 to the TOF sensor with a greater reduction in amplitude. In an example embodiment, the TOF sensor may be an ultrasonic sensor, a LIDAR (light detection and ranging) sensor, a radar sensor, a single zone optical TOF sensor, or a multi-zone TOF sensor. In this regard, the carrier wave 215 may be a radar wave, a light wave, or an acoustic wave, an example of which may be an ultrasonic wave. A multi-zone TOF sensor may have the ability to respond differently to detecting an object by dividing the field of view 230 into multiple smaller zones. As such, the multi-zone TOF sensor may be better suited for detecting object behavior in specific orientations depending on the arrangement of the zones within the field of view 230.

[0021] In this regard, in an example embodiment, the sensor array 210 may include time-of- flight sensors. The time-of-flight sensors may continuously scan the field of view 230 by generating a plurality of carrier waves 215 and, in some cases, record data which may include the time it takes the carrier wave 215 to travel to the object and reflect back to the sensor array 210. The sensor array 210 may communicate the data to a controller 140 that may use the data to determine when a trigger event occurs. In some embodiments, the object may be a human body part 250. The controller 140 may be able to determine that the object is the human body part 250 based on the reflected carrier wave 215 strength. In this regard, the data from the sensor array 210 may also include an indication of the reflected carrier wave 215 strength which may correlate to the reflectivity of the object. The human body part 250, both with and without PPE, may possess greater reflectivity than the object intended to be cut. In this regard, the controller 140 may utilize a data processing algorithm to determine the reflectivity of the object, and compare the reflectivity of the object to a predetermined reflectivity threshold. In some embodiments, if the reflectivity of the object exceeds the predetermined reflectivity threshold, then the controller 140 may determine that the object is a body part 250 with or without PPE and may initiate a protective action with respect to the power tool 200. In some cases, if the reflectivity of the object does not exceed the predetermined reflectivity threshold, then the controller 140 may determine that the object is not the body part 250 and may not initiate the protective action with respect to the power tool 200. Thus, in an example embodiment, the data recorded by the sensor array 210 may be used by the controller 140 to determine the distance to the object, the velocity of the object, and the nature of the object (i.e. whether or not the object is a body part 250 or a non-human object within the field of view 230). The controller 140 may be configured to respond differently to detecting the body part 250 in the field of view 230 versus detecting a non-human object in the field of view 230. As noted above, the human body part 250 is just one example of a detectable object entering the field of view 230. Other objects detectable by the sensor array 210 may include animals, parts of animals, or other objects possessing known reflective properties. In an example embodiment, the controller 140, via the data processing algorithm, may distinguish the object as a human body part 250 on its own via the reflectivity of the object. In some other cases, the data processing algorithm may be used in conjunction with a particular PPE fabric, the reflectivity of which may be known and accounted for in the data processing algorithm to more accurately identify the object as the human body part 250.

[0022] As depicted in FIGS. 2-6, in some embodiments, the field of view 230 may further include a protective zone 260. The protective zone 260 may be a boundary disposed entirely within the field of view 230, that extends a predetermined distance (DI) around all sides of the working assembly 220. In other words, the protective zone 260 may define a minimum distance around the working assembly 220 that the body part 250 may approach, occupy or exit, to define a trigger event. Accordingly, the trigger event may be related to the body part 250 contacting the protective zone 260. In this regard, the controller 140 may save and process the data from the time-of-flight sensors, which may include the location of objects within the field of view 230. By comparing saved time-of-flight data, as well as compiling new time-of-flight data, the controller 140 may be able to determine if the body part 250 may be entering or approaching (FIG. 3), may be disposed within (FIG. 4), or may be exiting the protective zone 260 (FIG. 5). Additionally, the controller 140 may be able to determine that the body part 250 may be moving too quickly towards the protective zone, or accelerating too quickly towards the protective zone. In either case, the controller 140 may initiate the protective action with respect to the power tool 200. Therefore, all of the distance, the velocity and the acceleration of the object may be causes of a trigger event. Thus, responsive to determining that the object is a body part 250 that may be entering/approaching, may be disposed within, or may be exiting the protective zone 260, the controller 140 may initiate the protective action with respect to the power tool 200.

[0023] In some embodiments, the field of view 230 may be much larger than the protective zone 260. In this regard, the protection assembly may record data from objects within the immediate field of view 230, even if those objects may not be located proximate to the protective zone 260. When the field of view 230 is much larger than the protective zone 260, the controller 140 may dynamically alter the size of the protective zone 260 based on whether or not the objects in the field of view 230 are determined to be human body parts 250, and the velocity and the acceleration of the body part 250 relative to the working assembly 220. As such, the maps or other data generated by the sensor array 210 may be used by the controller 140 to determine if the body part 250 is approaching the working assembly 220, and, if so, its velocity and acceleration. If the controller 140 determines that the body part 250 may be approaching the working assembly 220 at a velocity that exceeds a predetermined threshold velocity, then the controller 140 may enlarge the protective zone 260 to create a larger buffer between the human body part 250 and the working assembly 220 and allow more time for the protective action to take place. In contrast, if the controller 140 determines that the body part 250 may be approaching the working assembly 220 at a velocity that is less than a predetermined threshold velocity, then the controller 140 may reduce the protective zone 260 and create a smaller buffer between the human body part 250 and the working assembly 220 to allow for more precise and controlled operation of the power tool 200 in certain settings. In an example embodiment, the controller 140 may have similar responses for detecting the body part 250 accelerating towards the protective zone 260,. In this regard, if the body part 250 may be accelerating towards the working assembly 220 at an acceleration that exceeds a predetermined threshold acceleration, then the controller 140 may enlarge the protective zone 260. If the body part 250 may be accelerating towards the working assembly 220 at an acceleration that does not exceed a predetermined threshold acceleration, then the controller 140 may reduce the protective zone 260. In some cases, the predetermined threshold velocity and the predetermined threshold acceleration may be a function of the current size of the protective zone 260, the distance of the body part 250 to the protective zone 260 and the velocity and/or acceleration of the body part 250. In this regard, the predetermined threshold velocity and the predetermined threshold acceleration may be a function that may reflect the variety of conditions that must be met rather than a static numerical value.

[0024] As can be appreciated from the descriptions above, the sensor array 210 may be configured to measure or track distances or objects in either three dimensions, two dimensions, or simply in one dimension (i.e., straight line distance). In any case, distances or proximity measurements may be performed so that the power tool 200 (or at least the cutting action thereof) may be disabled based on distance or proximity thresholds that can be defined (e.g., for short distances), or based on combinations of relative position of the body part 250 and the tool at angular velocities or linear velocities from the IMU-based sensors 120 above certain thresholds (e.g., stop delay based distances for larger distances).

[0025] In an example embodiment, the controller 140 may be disposed at the power tool 200 and, in this case, may be provided within the housing 270 of the power tool 200. The controller 140 may be configured to communicate with the sensor array 210 and/or the IMU-based sensors 120 to perform object recognition and distance measuring and/or motion tracking as described herein. The controller 140 may have a wired or wireless connection to the sensor array 210. If communications between the IMU-based sensors 120 and the controller 140 occur, such communication may be accomplished via wireless communication (e.g., short range wireless communication techniques including Bluetooth, WiFi, Zigbee, and/or the like).

[0026] The sensor array 210 may communicate with the controller 140 to provide the data either on a continuous, periodic or event-driven basis. At one end of the spectrum, continuous data may be provided to, and evaluated by, the controller 140 at routine and frequent intervals. At the other end of the spectrum, the data may only be provided when the body part 250 interacts with the protective zone 260. The sample rate of the sensor array 210 may have a direct correlation to the accuracy of the measurement data obtained by the sensor array 210. In this regard, the higher the sample rate is, the more carrier waves 215 that are generated by the TOF sensor and the more accurate the recorded data regarding the distance, velocity and reflective properties of the object may be. In any case, the controller 140 may be configured to evaluate the data relative to initiation of warnings or other protective actions that the controller 140 may control. As an example, the protective action may include stopping any cutting operation (e.g., via activating a chain brake 170) of the chainsaw 100 in FIG. 1 responsive to the controller 140 determining that a trigger event has occurred. Alternatively or additionally, the protective action may include providing a warning (e.g., audibly, visually, or via haptic feedback). For example, if hearing protection 180 is worn by the operator 110 as shown in FIG. 1, an audible warning could be provided via the hearing protection 180. In some cases, the protective action may include both providing the warning and stopping any cutting operations (e.g., activating the chain brake 170).

[0027] The configuration of the controller 140 in accordance with an example embodiment will now be described in reference to FIG. 7. In this regard, FIG. 7 shows a block diagram of the controller 140 in accordance with an example embodiment. As shown in FIG. 7, the controller 140 may include processing circuitry 280 of an example embodiment as described herein. The processing circuitry 280 may be configured to provide electronic control inputs to one or more functional units of the power tool 200 (e.g., the chain brake 170) or the system (e.g., issuing a warning to the hearing protection 180) and to process data received at or generated by the one or more of the IMU -based sensors 120 or the sensor array 210 regarding various indications of movement or distance between the power tool 200 and the operator 110 or the body part 250. Thus, the processing circuitry 280 may be configured to perform data processing, control function execution and/or other processing and management services according to an example embodiment.

[0028] In some embodiments, the processing circuitry 280 may be embodied as a chip or chip set. In other words, the processing circuitry 280 may comprise one or more physical packages (e.g., chips) including materials, components and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The processing circuitry 280 may therefore, in some cases, be configured to implement an embodiment of the present invention on a single chip or as a single “system on a chip.” As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

[0029] In an example embodiment, the processing circuitry 280 may include one or more instances of a processor 282 and memory 284 that may be in communication with or otherwise control other components or modules that interface with the processing circuitry 280. As such, the processing circuitry 280 may be embodied as a circuit chip (e.g., an integrated circuit chip) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein. In some embodiments, the processing circuitry 280 may be embodied as a portion of an onboard computer housed in the housing 270 of the power tool 200 to control operation of the system relative to interaction with other motion tracking and/or distance measurement devices.

[0030] Although not required, some embodiments of the controller 140 may employ or be in communication with a user interface 290. The user interface 290 may be in communication with the processing circuitry 280 to receive an indication of a user input at the user interface 290 and/or to provide an audible, visual, tactile or other output to the operator 110. As such, the user interface 290 may include, for example, a display, one or more switches, lights, buttons or keys, speaker, and/or other input/output mechanisms. In an example embodiment, the user interface 290 may include the hearing protection 180 of FIG. 1 , or one or a plurality of colored lights to indicate status or other relatively basic information. However, more complex interface mechanisms could be provided in some cases.

[0031] The controller 140 may employ or utilize components or circuitry that acts as a device interface 300. The device interface 300 may include one or more interface mechanisms for enabling communication with other devices (e.g., the sensor array 210, the chain brake 170, the hearing protection 180, and/or the IMU-based sensors 120). In some cases, the device interface 300 may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive and/or transmit data from/to components in communication with the processing circuitry 280 via internal communication systems of the power tool 200 and/or via wireless communication equipment (e.g., a one way or two way radio). As such, the device interface 300 may include an antenna and radio equipment for conducting Bluetooth, WiFi, or other short range communication, or include wired communication links for employing the communications necessary to support the functions described herein.

[0032] The processor 282 may be embodied in a number of different ways. For example, the processor 282 may be embodied as various processing means such as one or more of a microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. In an example embodiment, the processor 282 may be configured to execute instructions stored in the memory 284 or otherwise accessible to the processor 282. As such, whether configured by hardware or by a combination of hardware and software, the processor 282 may represent an entity (e.g., physically embodied in circuitry - in the form of processing circuitry 280) capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when the processor 282 is embodied as an ASIC, FPGA or the like, the processor 282 may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the processor 282 is embodied as an executor of software instructions, the instructions may specifically configure the processor 282 to perform the operations described herein.

[0033] In an exemplary embodiment, the memory 284 may include one or more non- transitory memory devices such as, for example, volatile and/or non-volatile memory that may be either fixed or re-movable. The memory 284 may be configured to store information, data, applications, instructions or the like for enabling the processing circuitry 280 to carry out various functions in accordance with exemplary embodiments of the present invention. For example, the memory 284 could be configured to buffer input data for processing by the processor 282. Additionally or alternatively, the memory 284 could be configured to store instructions for execution by the processor 282. As yet another alternative or additional capability, the memory 284 may include one or more databases that may store a variety of data sets. Among the contents of the memory 284, applications may be stored for execution by the processor 282 in order to carry out the functionality associated with each respective application. In some cases, the applications may include instructions for motion tracking and/or object recognition and distance measuring and distance tracking as described herein.

[0034] As stated above, the sensor array 210 may communicate the data to the controller 140, which may use the data to determine when a trigger event occurs. In this regard, the data may accordingly be communicated from the sensor array 210 to the memory 284 via the device interface 300 and the processor 282. In some cases, the memory 284 may save the data in a circular buffer. In other words, a set amount of storage space may be available in the memory 284 and in order to save new data from the sensor array 210, the memory 284 may overwrite the oldest saved data with the newest saved data. The processor 282 may then access the memory 284 under the direction of an application from the memory 284 to compare numerous sets of saved data from the sensor array 210 to determine the change in distance of the object in the field of view 230 over time and to determine the reflectivity of the object. In some cases, the data from the sensor array may include the time the carrier wave 215 takes to travel to and reflect back from the object, which may be used to determine the distance of the object. The velocity and acceleration of the object may be determined by comparing the change over time of the data from the sensor array 210. In other words, the velocity may be determined by comparing saved data to see how quickly the distance to the object is changing, and the acceleration may be determined by comparing saved data to see how quickly the velocity is changing. All of the distance, the velocity and the acceleration of the object may be causes of a trigger event. That is, if the controller 140 determines that the object is the body part 250 that is too close to the protective zone, moving too quickly towards the protective zone, or accelerating too quickly towards the protective zone, then the controller 140 may initiate the protective action with respect to the power tool 200.

[0035] Accordingly, in one example embodiment, a protection assembly for a power tool may be provided. The protection assembly may include a sensor array disposed at the power tool, and a controller which may include processing circuitry configured to determine whether to initiate a protective action with respect to the power tool. The sensor array may define a field of view that may surround a working assembly of the power tool. The field of view may include a protective zone. The controller may process data from the sensor array to determine when a trigger event may occur while the power tool may be in operation. The sensor array may include a time-of-flight sensor disposed on a front face of the power tool, proximate to the working assembly.

[0036] The protection assembly of some embodiments may include additional, optional features, and/or the features described above may be modified or augmented. Some examples of modifications, optional features and augmentations are described below. It should be appreciated that the modifications, optional features and augmentations listed below may each be added alone, or they may be added cumulatively in any desirable combination. For example, in some embodiments, the protective zone may define a minimum distance around the working assembly. In some cases, the trigger event may include any one of a body part entering the protective zone, the body part being in the protective zone, the body part exiting the protective zone, or the body part moving towards the protective zone with a velocity exceeding a predetermined threshold. In an example embodiment, the time-of-flight sensor may record data that the controller may use to determine when the trigger event may occur. In some cases, the data may include the time required for a carrier wave to travel from the time-of-flight sensor to an object in the field of view and back to the time-of-flight sensor. In an example embodiment, the time-of-flight sensor in the sensor array may continuously scan the field of view, and the processing circuitry may save and processes the data from the time-of-flight sensor. In some cases, the controller may determine if the body part may be entering, may be disposed within, may be exiting, or may be moving towards the protective zone by comparing data saved by the processing circuitry. In an example embodiment, the power tool may be a chainsaw. In some cases, the working assembly may include a chain and a guide bar. In an example embodiment, the protective action may include activating a chain brake of the chainsaw responsive to the controller determining that a trigger event has occurred. In some cases, the power tool may be a chainsaw or power cutters. In an example embodiment, the working assembly may include a chain and guide bar or a cutting blade. In some cases, the protective action may include providing an audible or visual warning to an operator responsive to the controller determining that a trigger event has occurred. In an example embodiment, the time-of-flight sensor may be a LIDAR sensor.

[0037] Some example embodiments may provide for a power tool. The power tool may include a working assembly which may perform a cutting operation, a powerhead which may power the working assembly, a housing which may be operably coupled to the working assembly and may contain the powerhead, and a protection assembly. The protection assembly may include a sensor array disposed at the power tool, and a controller which may include processing circuitry configured to determine whether to initiate a protective action with respect to the power tool. The sensor array may define a field of view that may surround a working assembly of the power tool. The field of view may include a protective zone. The controller may process data from the sensor array to determine when a trigger event may occur while the power tool may be in operation. The sensor array may include a time-of-flight sensor disposed on a front face of the power tool, proximate to the working assembly. [0038] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. In cases where advantages, benefits or solutions to problems are described herein, it should be appreciated that such advantages, benefits and/or solutions may be applicable to some example embodiments, but not necessarily all example embodiments. Thus, any advantages, benefits or solutions described herein should not be thought of as being critical, required or essential to all embodiments or to that which is 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

THAT WHICH IS CLAIMED:

1. A protection assembly for a power tool (200), the protection assembly comprising: a sensor array (210) comprising a time-of-flight sensor disposed on a front face of the power tool (200) proximate to a working assembly (220) of the power tool (200); and a controller (140) comprising processing circuitry (280) configured to initiate a protective action with respect to the power tool (200) responsive to a trigger event occurring while the power tool (200) is in operation based on input from the sensor array (210), wherein the sensor array (210) defines a field of view (230) that surrounds the working assembly (220) of the power tool (200), and wherein the field of view (230) comprises a protective zone (260).

2. The protection assembly of claim 1 , wherein the protective zone (260) defines a minimum distance around the working assembly (220).

3. The protection assembly of claim 1, wherein the controller (140) determines a reflectivity of an object in the field of view (230), and wherein the controller (140) determines that the object is a body part (250) if the reflectivity exceeds a predetermined reflectivity threshold.

4. The protection assembly of claim 3, wherein the trigger event comprises any one of the body part (250) disposed in the protective zone (260), the body part (250) moving toward the protective zone (260) at a velocity that exceeds a predetermined threshold velocity, or the body part (250) accelerating toward the protective zone (260) at an acceleration that exceeds a predetermined threshold acceleration.

5. The protection assembly of claim 4, wherein the time-of-flight sensor records data comprising a time a carrier wave (215) takes to travel from the time-of-flight sensor to the body part (250) and back to the time-of-flight sensor which the controller (140) compares to determine when the trigger event occurs.

6. The protection assembly of claim 5, wherein the time-of-flight sensor in the sensor array (210) continuously scans the field of view (230), and the processing circuitry (280) saves and processes the data from the time-of-flight sensor.

7. The protection assembly of claim 6, wherein the controller (140) determines if the body part (250) is disposed within, is moving towards, or is accelerating towards the protective zone (260) by comparing data saved by the processing circuitry (280).

8. The protection assembly of claim 1, wherein the power tool (200) is a chainsaw (100), wherein the working assembly (220) comprises a chain (102) and a guide bar, and wherein the protective action comprises activating a chain brake (170) of the chainsaw (100) responsive to the controller (140) determining that the trigger event has occurred.

9. The protection assembly of claim 1, wherein the power tool (200) is a chainsaw (100) or power cutters, wherein the working assembly (220) comprises a chain (102) and guide bar or a cutting blade, and wherein the protective action comprises providing an audible or visual warning to an operator (110) responsive to the controller (140) determining that the trigger event has occurred.

10. The protection assembly of claim 1, wherein the time-of-flight sensor is an ultrasonic sensor, a LIDAR (light detection and ranging) sensor, a radar sensor, a single zone optical TOF sensor, or a multi-zone TOF sensor.

11. A power tool (200) comprising: a working assembly (220) to perform a cutting operation; a powerhead to power the working assembly (220); a housing (270) operably coupled to the working assembly (220) and containing the powerhead; and a protection assembly, wherein the protection assembly comprises: a sensor array (210) comprising a time-of-flight sensor disposed on a front face of the power tool (200) proximate to the working assembly (220) of the power tool (200); and a controller (140) comprising processing circuitry (280) configured to initiate a protective action with respect to the power tool (200) responsive to a trigger event occurring while the power tool (200) is in operation based on input from the sensor array (210), wherein the sensor array (210) defines a field of view (230) that surrounds the working assembly (220), and wherein the field of view (230) comprises a protective zone (260).

12. The power tool (200) of claim 11, wherein the protective zone (260) defines a minimum distance around the working assembly (220).

13. The power tool (200) of claim 11, wherein the controller (140) determines a reflectivity of an object in the field of view (230), and wherein the controller (140) determines that the object is a body part (250) if the reflectivity exceeds a predetermined reflectivity threshold.

14. The power tool (200) of claim 13, wherein the trigger event comprises any one of the body part (250) disposed in the protective zone (260), the body part (250) moving toward the protective zone (260) at a velocity that exceeds a predetermined threshold velocity, or the body part (250) accelerating toward the protective zone (260) at an acceleration that exceeds a predetermined threshold acceleration.

15. The power tool (200) of claim 14, wherein the time-of-flight sensor records data comprising a time a carrier wave (215) takes to travel from the time-of-flight sensor to the body part (250) and back to the time-of-flight sensor which the controller (240) compares to determine when the trigger event occurs.

16. The power tool (200) of claim 15, wherein the time-of-flight sensor in the sensor array (210) continuously scans the field of view (230), and the processing circuitry (280) saves and processes the data from the time-of-flight sensor.

17. The power tool (200) of claim 16, wherein the controller (140) determines if the body part (250) is disposed within, is moving towards, or is accelerating towards the protective zone (260) by comparing data saved by the processing circuitry (280).

18. The power tool (200) of claim 11, wherein the power tool (200) is a chainsaw (100), wherein the working assembly (220) comprises a chain (102) and a guide bar, and wherein the protective action comprises activating a chain brake (170) of the chainsaw (100) responsive to the controller (140) determining that the trigger event has occurred.

19. The power tool (200) of claim 11, wherein the power tool (200) is a chainsaw (100) or power cutters, wherein the working assembly (220) comprises a chain (102) and guide bar or a cutting blade, and wherein the protective action comprises providing an audible or visual warning to an operator (110) responsive to the controller (140) determining that the trigger event has occurred.

20. The power tool of claim 11, wherein the time-of-flight sensor is an ultrasonic sensor, a LIDAR (light detection and ranging) sensor, a radar sensor, a single zone optical TOF sensor, or a multi-zone TOF sensor.