Safety device for a machine tool

Abstract

The invention relates to a safety device for a machine tool, comprising: - a detection device which is designed for detecting a potential state of risk to a body part of a user of the machine tool resulting from a component of the machine tool that could cause injury, - a safety measure device which is designed to execute a safety measure by way of which a state of risk to the user of the machine tool resulting from a component of the machine tool is reduced or avoided, - a control device which is coupled in a signal-transmitting manner to the detection device and the safety measure device and is designed to carry out an assessment of a potential state of risk detected by the detection device on the basis of predetermined criteria and to activate the safety measure device for executing a safety measure depending on the assessment, characterized in that the detection device comprises a head strap for fastening to the head of the user and an image recording device fastened to the head strap and designed to record images in the field of vision of the user, and the control device is designed to carry out the assessment on the basis of images recorded by the image recording device.

Description

[0001] Safety device for a machine tool

[0002] The invention relates to a safety device for a machine tool.

[0003] Safety devices for machine tools are intended to prevent injuries to the machine tool operator. Such injuries can occur if, starting from a potentially hazardous situation, a movement of a part of the operator's body or a component of the machine tool (or both) continues and this results in contact between the component and the body part. Typical injuries in this case are cuts or crushing injuries, which often occur primarily to the user's hand. In other cases, however, a potentially hazardous situation can also lead to a component on the workpiece becoming jammed, which can accelerate chips or the entire workpiece in a direction that could cause injury, thereby injuring other parts of the user's body, for example the eyes.

[0004] Various solutions for preventing injuries by means of safety devices on machine tools are already known. These solutions aim, for example, to monitor the movement area around a machine tool, such as an automation robot, using image capture and to stop the robot's movements if a person enters this movement area. For example, US 2002 / 0170399 A1 discloses a system in which contact between skin and circular saw blade is detected by an electrical conductivity measurement via an electrical voltage applied to the circular saw blade, and as a result, a dangerous condition is recorded. As a subsequent safety measure following a signal obtained in this way, a preloaded spring is released, and the released spring force is used to press a plastic element into the cutting edge of the circular saw blade.From WO 2004 / 101239 a safety system is known in which, in a dangerous situation, the circular saw blade is pulled under the table or the drive is decoupled from the circular saw blade in order to achieve a braking of the circular saw blade by the workpiece.

[0005] US Pat. No. 9,702,916 B2 discloses a safety device that is also intended for use in circular saws. Hazard detection is performed using calibration and SNR calculation. When a hazard occurs, the motor is deactivated and a cutting tool locking mechanism is activated simultaneously to stop the circular saw blade.

[0006] From WO 2017 / 059 473 A1 a method for detecting human tissue in the vicinity of a tool by detecting a periodic change in capacitance is known.

[0007] A safety system for circular saws is already known from US 2016 / 0 279 754 A9. By listing alternative or additional detection measures and action measures, contact or proximity to the saw blade is described as a detection criterion for a hazardous situation, and a saw blade stop and lowering is described as an action measure in the event of a hazardous situation.

[0008] A safety system for circular saws is already known from WO 2016 / 145157 A1. It uses a capacitive measurement to detect contact or proximity of a body part to the saw blade. Upon approach, the motor is stopped, but upon contact, a pyrotechnic braking device is triggered. Detection of the hazardous condition is capacitive.

[0009] WO 2015 / 091245 A1 describes an optical detection system for detecting skin tones and calculating the proximity of body parts to the saw blade. The reaction mechanisms described include stopping or lowering the saw blade. This involves detecting a dangerous situation in the form of an approach below a certain distance or exceeding a certain approach speed as the trigger criterion.

[0010] A safety system for circular saws is already known from US 2014 / 0 331 833 A1. It is based on a capacitive measurement and is designed to detect contact or proximity of a body part with the saw blade. The machine's response to a hazardous situation is described as stopping the cutting movement of the cutting tool. A hazardous situation is detected as either the proximity of or contact with the cutting tool.

[0011] US 2014 / 0 090 948 A1 discloses the detection of a hazardous condition when a body part approaches the saw blade using infrared temperature detection. The speed of an object is detected, including the direction of movement and the rate of movement. Depending on this detected speed, a decision is then made as to whether the drive is deactivated or whether a brake is activated.

[0012] WO 2013 / 046522 A1 describes monitoring a hazardous area using a triple sensor arrangement and stopping the saw blade when an object enters this hazardous area. Only objects that reflect electromagnetic waves in a specific way are detected; an example is an RFID tag attached to the distal end of the thumb of a work glove. An alarm signal is issued in parallel with the stopping of the saw blade in a hazardous situation.

[0013] WO 2014 / 164 964 A1 describes the detection of a workpiece, including the material type of the workpiece, in order to optimize the resulting cutting parameters. The speed of a circular saw blade is then controlled based on these parameters. The workpiece is detected using a material sensor with regard to its geometric length in the cutting direction, and at the end of the cut, the speed is reduced to reduce splinter formation and the associated risk of injury to the operator.

[0014] US 2011 / 0 226 105 A1 describes various safety devices on circular saws, addressing both the detection of hazardous situations and the action to be taken in the event of a hazardous situation. Various sensor systems are disclosed for detecting hazardous situations and various actions are described for avoiding hazardous situations. These include stopping the saw blade, lowering the saw blade, forming a protective shield around the saw blade (airbag), and acoustic or visual signals. The levers shown in Figure 16, which are intended to cover the cutting edges of the saw blade in hazardous situations, do not appear to represent a reliably effective safety device from a technological perspective when the tool is in contact with a workpiece.

[0015] US 2009 / 0 301 275 A1 describes the detection of a human body part using electromagnetic waves in the 400 nm to 1,500 nm wavelength range and the avoidance of hazardous situations by covering the saw blade and stopping it. The document describes the detection of a hand in a hazardous area as the triggering event.

[0016] DE 10 2007 062 996 A1 describes a safety device for circular saws with a stopping or lowering function for the circular saw blade. Hazardous conditions are detected by identifying a body part and its direction of movement within a hazardous area. The device also describes the observation and comparison of two different movements.

[0017] DE 10 2008 001 727 A1 basically describes a protective device that uses detection by means of sensors, in particular distance sensors, and an action by lowering the saw blade into a protective position.

[0018] DE 10 2009 054 491 A1 describes a safety device for circular saws that relies on the detection of a specifically designed glove worn by the operator. By detecting electromagnetic radiation in the UV range, the position of this glove is determined, and depending on whether the operator enters a hazardous area, a protective cover is triggered to cover the circular saw blade.

[0019] DE 20 2010 004 458 U1 describes a safety system in which a sensor system detects body parts in the inlet area. It describes a detection of the hazardous situation based on a criterion, and the action to prevent the hazard is either shielding the circular saw blade or lowering the saw blade below the table.

[0020] DE 20 2011 101 566 U1 describes a quick-lowering device for the circular saw blade to prevent hazardous situations. A safety device is already known from DE 20 2019 102 935 U1, which is also suitable, for example, for panel saws. A panel saw is generally known from EP 2 527 069 A1, DE 20 2009 007 150 U1, or WO 2012 / 159956 A1. The safety device described in DE 20 2019 102 935 U1 uses image capture to monitor a danger zone around the circular saw blade of the panel saw. If the distance between a user's hand and the circular saw blade is detected to be too small, the circular saw blade is lowered below the machine tool table to prevent contact with the user's hand. The image capture is carried out by means of an image capture device which is arranged on a cantilevered arm in a vertical direction above the workpiece support surface.

[0021] DE 11 2019 000228 T5 discloses a system comprising a headset with a stereoscopic camera. The headset has one or more ranging sensors and motion sensors and can execute simultaneous localization and mapping algorithms. These sensors and algorithms enable the system to calculate the entire kinematic movement of a chainsaw and to detect and localize hand gestures for determining a relative position between the chainsaw, a user position, a cutting tool, and the workpiece. Using this information, the system can also trigger a reactive device if the relative position of the user (including extremities) is within a predetermined restricted zone of the chainsaw or approaches this restricted zone at a speed and within a proximity above a predetermined threshold.In another embodiment of DE 11 2019 000228 T5, the tool may be a table saw and the reactive device may be alerted by the system to quickly stop a saw blade.

[0022] In principle, safety devices of this type can significantly improve the safety of the machine tool user and prevent injuries in certain machine tools during normal use. However, problems still exist in that in special situations, such as unusual machining processes, workpiece shapes, or the like, the detection device can reliably detect a potentially hazardous condition. In such cases, a precautionary safety measure is often taken, and machining of the workpiece with the machine tool cannot then be continued. This is disadvantageous and can lead to the user deactivating the safety device in order to use the machine tool without the active safety device, which then creates a risk of injury similar to that found on conventional machine tools without a safety device.

[0023] Another disadvantage of previously known solutions is that previously known safety devices are often suitable for certain machine tools, but are not designed for use on other types of machine tools. In particular, hand-held machine tools, i.e., hand tools such as drills, jigsaws, hand-held circular saws, or angle grinders, cannot be operated with previously known safety devices in a manner that satisfactorily reduces the risk of injury to the user.

[0024] There is therefore a need for a safety device that enables a better reduction of the risk of injury to the user in special situations on stationary machine tools or hand-held machine tools.

[0025] According to the invention, this object is achieved by a safety device of the type described above, in which the detection device comprises a head mount for attachment to the user's head and an image capture device fastened to the head mount, which is aligned to carry out an image capture in the user's field of vision, and in which the control device is designed to carry out the assessment on the basis of images captured by the image capture device.

[0026] The safety device according to the invention fundamentally comprises a detection device, a safety measure device, and a control device. The detection device serves to detect a potentially hazardous condition for a body part of a machine tool user caused by a component of the machine tool that is at risk of injury. Such a potentially hazardous condition is to be understood as a condition that could result in injury to the user if continued operation is continued as before. The injury can occur in a body part such as a hand or an arm. In many cases, the detection device will therefore also detect the body part at risk of injury and monitor its movement.The risk of injury can originate from any component of the machine tool. This can be, in particular, a cutting tool such as a saw blade, especially a circular saw blade of a machine tool. However, other tools such as milling tools, turning tools, and drilling tools can also be considered as components posing a risk of injury. The risk of injury can also originate from a component such as a clamping or guiding device or crushing components of the machine tool. In many cases, the detection device will also detect the component posing a risk of injury and is therefore designed to detect both the body part at risk of injury and the component posing a risk of injury, thereby capturing the potential hazard in an image.

[0027] The safety measure device is designed to implement a safety measure when a potentially hazardous condition has been detected. In the simplest case, such a safety measure can consist of a danger signal that visually or acoustically warns the machine tool user of the danger. In many cases, however, an active mechanical measure on the machine tool is implemented as a safety measure by the safety measure device either downstream of or instead of such a danger signal. For example, braking – possibly even stopping – the potentially injury-prone component, moving the potentially injury-prone component to an area where it no longer poses a risk of injury, or shielding the potentially injury-prone component with a shielding device to prevent contact between the body part and the component.The security measures device can also implement several different security measures according to a hazard catalogue, for example in the form of different escalation levels, in order to respond appropriately to different hazard levels.

[0028] Both the detection device and the safety measure device are signal-coupled to a control device. This signal-coupled connection can be wired or wireless and serves to exchange data between the control device, the detection device, and the safety measure device. The control device can be attached to the headgear itself or can be carried by the user independently of the headgear, for example, as a separate control device that is signal-coupled to the image capture device via data transmission. For example, the control device can be implemented in a smartphone that is coupled to the image capture device via fast signal transmission such as Bluetooth or 5G.The control device is fundamentally designed to evaluate states detected by the detection device and to identify a potential hazardous state from these states. This preferably occurs in real time. To this end, the control device applies predetermined criteria with which it compares the actual state detected by the detection device. Such criteria can be a predetermined safety distance, but can also be a safety distance dependent on the movement speed or acceleration or the direction of movement or acceleration of the hand, which is calculated according to predetermined criteria.Furthermore, the control device can incorporate additional predetermined criteria into the evaluation, for example, when, in addition to the relative distance, speed, acceleration, and their direction between the injury-risk component and the body part, other aspects, such as the size or weight of the injury-risk component, must also be considered. This can be advantageous, for example, with interchangeable tools on a machine tool, or when setting parameters of the injury-risk component on the machine tool must be taken into account, such as a varying travel distance, which can be longer or shorter depending on a presetting parameter of the tool (such as a cutting height or the like), up to a safe, injury-free position.Furthermore, criteria related to the user can also be taken into account by the control device, for example whether the user is experienced or inexperienced, and the situation detected by the detection device can then be assessed as a potential hazardous condition or not, depending on the user, using different predetermined criteria.

[0029] If the control device determines, based on the situation detected by the detection device, that a potentially hazardous condition exists, it triggers the safety measure device to execute a safety measure. The control device can control a single safety measure or, in turn, select a safety measure appropriate for the detected potentially hazardous condition from several different safety measures and control it. This selection of a suitable safety measure can also be based on predetermined criteria.

[0030] According to the invention, the detection device comprises a headgear for attachment to the user's head and an image capture device attached to the headgear, which is aligned to capture an image in the field of vision of the user wearing the headgear. The detection device is therefore designed to detect a potential hazardous condition by means of image capture, and the image capture device required for this purpose is arranged on a headgear worn by the user. The image capture device is aligned to capture an image in the user's field of vision, i.e., typically, an image capture device is attached to the headgear, aligned in a straight-ahead line of sight of the user, and has an image capture area that corresponds at least to that which a user perceives with their eyes when looking straight ahead.The image capture device can also be aligned and designed to capture a larger area than the area captured by the user in the straight-ahead line of sight, in order to be able to determine a potential hazardous condition based on the capture of components or body parts that are potentially hazardous and are outside the user's actual line of sight.

[0031] The headgear can, for example, be a pair of glasses to which one or two cameras are attached as an image capture device, for example, on the sides of the glasses. Such glasses, also referred to as data glasses, then serve to capture images in the direction of the face orientation of the wearer of the data glasses. In other embodiments, the headgear can also be designed as a helmet, headband, cap, or the like, which is worn by the user on the head and to which the image capture device is attached. This can again be one or two cameras, for example, two video cameras attached to the side of the helmet or headband.In principle, the detection device designed in this way has the advantage that it carries out the image capture in the user's field of vision, i.e. it carries out the head movements and head swivels of the user and is therefore, on the one hand, favorably aligned with a danger zone that the user observes with his eyes, and on the other hand, it allows a conclusion to be drawn about the user's line of sight, thus also making it possible to detect if the user turns his head away from the danger zone in a potentially dangerous manner.

[0032] In the safety device according to the invention, the control device is designed to evaluate whether a potentially hazardous situation exists due to the situation detected by the detection device, based on the images captured by the image capture device on the data glasses. These images can be a single image, but typically, consecutive images are captured by the image capture device in the manner of a continuous real-time video capture of the current situation and evaluated by the control device to determine whether this results in a potentially hazardous situation.The recording and evaluation based on such consecutive images from a video surveillance system allows, on the one hand, continuous monitoring; on the other hand, the speeds of movement, accelerations of movement and directions of movement of the body part and, if applicable, of the component at risk of injury can be recorded from the consecutive images, thus enabling a differentiated assessment of the situation with regard to a potential hazardous condition.

[0033] The positioning of the image capture device on the head mount provides several advantages. Firstly, during normal use, the image capture device is optimally aligned to the area that is also highly relevant for assessing a potentially hazardous situation, because the user typically aligns their field of vision to precisely this area while machining a workpiece with the machine tool. Therefore, positioning the image capture device on the head mount can often achieve better monitoring of the relevant area around the potentially injury-prone component than if the image capture were performed using a stationary image capture device mounted on the machine tool.According to the inventors, the often better alignment of the image capture device to the head mount is an advantage that can, in many situations, outweigh the associated disadvantage that neither the alignment nor the detection range of the capture device is predetermined, which would be guaranteed with a stationary image capture device, and leads to improved functionality of the safety device. At the same time, the image capture device according to the invention makes it possible to determine whether the user is actually looking at the relevant area or whether they have turned their head away from the relevant area and therefore could not even recognize a potentially hazardous situation, which was not possible with previously known safety devices.The image capture device on the headgear therefore allows such averted field of vision to be detected, because in this case, the body part and / or the component at risk of injury would not be detectable in the image capture. In such a case, a potentially hazardous condition could be inferred because the user himself is inadequately monitoring the processing.

[0034] Finally, a further advantage of the safety device according to the invention is that image capture using a head mount with image capture device can be used for many machine tools for which previous safety devices could not be used, for example with hand tools, where the user regularly has the relevant area for determining a potential hazardous condition in his field of vision by wearing the head mount with image capture device and can therefore also be captured by the image capture device and consequently evaluated by the control device.

[0035] According to the invention, it was recognized that the safety device according to the invention is not limited to application on machine tools in the narrow sense, but can protect a user from injury in many situations. Thus, by means of image acquisition by the image acquisition device attached to the headgear and the control device, it is also possible to monitor, by means of image analysis, an activity performed manually by the user or with a hand tool, for example, manual activities by an electrician on a control cabinet. In such applications, objects that pose a risk of injury and are captured by the image acquisition device can be detected by image analysis, and any movement of a part of the user's body that could lead to an injury-threatening proximity or contact with these objects can be identified.For example, the insulated end of an electrical cable could be identified as a potentially hazardous object through image analysis, and a dangerous approaching movement of the hand of an electrician wearing the headgear with image capture device could be determined as a potential hazard. In such a case, an acoustic or visual warning signal could be issued as a safety measure, for example, or a power cut could be initiated by a safety device. For the purposes of the invention, a machine tool is therefore generally understood as a device that has a potentially hazardous component.In general, a vehicle or other moving object can therefore also be understood as a machine tool within the meaning of the invention, and through image analysis, a potential contact that can arise from the movement of such a vehicle or object and the movement of the body part of the user or the user himself is understood as a potential hazardous condition.

[0036] According to a first preferred embodiment, the control device is designed to recognize the body part of the user and the component of the machine tool by means of image analysis in the image captured by the image capture device and to trigger the safety measure depending on this detection. According to this embodiment, the triggering of a safety measure occurs depending on the detection of an image of the body part of the user and the component of the machine tool that poses a risk of injury. This dependency can consist, on the one hand, in the body part and the component being evaluated with regard to their relative distance, their movement relative to one another, or their acceleration relative to one another, and from this, if appropriate, a potential hazardous condition is recognized and a safety measure is triggered.However, the dependence on detection can also mean that if one of the two, either the body part or the hazardous component or both, is not detected by the image capture device, a safety measure is triggered because in this case it must be assumed that the user has not aligned his head towards the hazardous area.

[0037] According to a further preferred embodiment, the control device is designed to determine a distance, an approach speed, or an approach acceleration between the body part and the component by means of image analysis as a hazard parameter and to trigger the safety measure depending on one or more of these hazard parameters. Approach speed and acceleration can be understood as the amount of movement or relative speed of the body part or the component, or of the two, to one another, and approach acceleration can be understood as the corresponding amount of acceleration. However, the direction of the speed or acceleration can also be taken into account, and consequently the speed vector component or acceleration vector component is determined.According to this development, the control device can determine a distance, an approach speed or an approach acceleration as relative parameters between the body part and the component and can perform an evaluation from one, two or all three parameters in order to conclude a potential hazardous condition.Such an assessment makes it possible to carry out a differentiated analysis, particularly when at least the distance and approach speed, and preferably also the approach acceleration, are included in the assessment. For example, when a body part and a component approach each other at a high approach speed and possibly also at a high approach acceleration, the safety measure can be implemented at a greater distance than if the approach speed and approach acceleration are low, and thus a safety measure would only have to be triggered at a smaller distance between body parts and components. This avoids false triggering and allows experienced users, in particular, to carry out work with the safety device according to the invention that requires the body part to be within a short distance of a hazardous component.

[0038] It is even further preferred if the control device is designed to use image analysis to determine, as hazard parameters, a distance of the body part from the image capture device, or a distance of the component from the image capture device, or a relative direction of movement of the component and body part to one another, or a relative direction of acceleration of the component and body part to one another, and to trigger the safety measure depending on one or more of these hazard parameters. According to this embodiment, a distance of the body part and a distance of the component from the image capture device are determined based on image analysis, and furthermore, a relative direction of movement of the component and body part to one another and a relative direction of acceleration of the component and body part to one another are determined.The direction of movement and the direction of acceleration can also be determined from the direction of movement of the component and body part relative to the image capture device. By determining the distance, direction of movement, speed of movement, and acceleration, or individual parameters, a differentiated assessment can be performed. Based on these assessments, a safety measure or a suitable safety measure from a catalog of several safety measures can be selected and triggered.

[0039] It is even more preferred if the control device is configured to determine the position, speed, and / or acceleration of the machine tool component by means of image analysis based on data processing with artificial intelligence used in the image analysis, or an image-capturable marking on the tool, or an operator input, or position data received from a transmitting device on / in the component. According to this embodiment, the control device operates, for example, with artificial intelligence to perform image analysis and assess the situation with regard to any potential hazardous condition.The use of artificial intelligence can, for example, enable a continuous, gradual improvement of the image analysis processes and the evaluation processes of the control device by updating the control device based on detected hazardous situations – if necessary, also by means of corresponding data transmission from detected hazardous situations of other devices – and thereby continuously updating the predetermined criteria. The control device can also be equipped with artificial intelligence so that it adapts its predetermined evaluation criteria based on stored operating sequences and the resulting hazardous situations in order to better evaluate typical processing sequences.

[0040] The control device can further preferably be configured to detect a predetermined marking on the component, for example, to reliably detect a correspondingly marked tool. The marking can be implemented as a color marking, engraving, or code, such as a QR code, and can additionally contain information about the component, such as its weight or dimensions. Such an image-capturable marking can significantly improve the control device's ability to detect a hazardous component from the image data of the image capture devices.

[0041] Alternatively or additionally, the control device can also carry out the assessment in response to an input from the operator. For example, the operator can manually mark a hazardous component in an image by means of such an input and thereby identify it to the control device, which can then carry out the assessment for a potential hazardous condition by evaluating the image and tracking this marked component.

[0042] Finally, the control device can also be configured to perform the assessment based on position data transmitted by a transmitting device on the hazardous component. For this purpose, an RFID unit can be installed on the component, for example, allowing for reliable location determination or determination of operating parameters of the component or machine tool, which can be incorporated into the assessment of the situation for a potential hazardous condition.It is even further preferred if the image capture device or the control device is configured to perform an image analysis to determine an image section of the captured image that corresponds to a predetermined field of view or section of the field of view of a user wearing the headgear, in particular a section corresponding to the fovea of ​​the field of view, and the control device is configured to determine, by means of an image analysis, whether the component is located within the image section and to control the safety measure device to execute a safety measure if the component is not located within the image section. The predetermined field of view can correspond to the user's field of view or their field of view, or can correspond to a section thereof.According to this embodiment, the image capture device or the control device captures an image area that corresponds to a predetermined field of view or section of the user's field of view. In particular, this can correspond to the fovea of ​​the field of view, i.e. the area that a user has approximately in the center of their field of view and which they can monitor with concentration. The image capture device is therefore aimed at or covers precisely such an image area that can also be reliably captured by the user when observing with their eyes. Based on an image analysis, it can then be determined whether the hazardous component is located within this image section. In this case, it is ensured that when the component is captured in the image section, the user also has the component in their concentratedly monitored field of view, and a decision can then be made as to whether or not a potentially hazardous situation exists.However, if the component is not detected within the image section, the situation must be assessed in such a way that the user is not safely monitoring the component and in this case, according to this training, the control device is designed to trigger a safety measure.

[0043] It can preferably further be provided that a device for eye tracking is attached to the headrest and that the image section is determined depending on the user's line of sight determined by means of eye tracking. By tracking the user's eyes, it can also be determined in which direction the user's eye is currently looking, i.e. whether, for example, the user is not looking straight ahead but to the side. This makes it possible to determine whether the user, although their head is positioned so that the central, straight-ahead line of sight is directed towards the hazardous component, deviates from this main axis with their gaze and therefore does not have the component in their line of sight, which in turn would indicate a potential hazardous condition and trigger a safety measure.According to a further preferred embodiment, the safety measure comprises a reduction in the movement speed of the component, a movement of the component into a position with less risk, a shielding of the component, and / or an activation of a warning signal in a signal output device arranged on the headgear. In principle, these four different categories of safety measures are possible in order to prevent injury to the user or to reduce the likelihood of injury. In principle, a reduction in the movement speed of the component can consist of a deceleration of a translational or rotational movement of the component with which the component changes location, or a rotational speed of the component can be reduced when the rotation axis is stationary; in particular, the reduction can consist of a rapid stopping of the movement of the component.The safety measure can also consist of moving the component from a hazardous position to a non-hazardous position, for example, lowering it under a table or moving it into a shield or away from the workpiece. Alternatively or additionally, the component can also be shielded, for example, by moving a separating grid, a deflector, or the like, to prevent the body part from coming into contact with the component and thereby being injured.Finally, a warning signal can also be activated in a signal output device arranged on the headgear, for example a warning light can be projected into the user's eye or a message can be displayed to the user's eye via the signal output device, which indicates a hazardous situation using augmented reality, for example by the signal output device marking a hazardous component with a signal color that is projected into the user's eye, or by an insufficient safety distance being indicated by a display projected into the distance or the component.

[0044] It is even more preferred if the control device is configured to distinguish between a low and a higher hazard level and to execute a first safety measure, in particular a warning signal, at the low hazard level and to execute a second safety measure, which is different from the first safety measure, at the higher hazard level. According to this embodiment, the control device can execute differentiated safety measures that are triggered depending on a higher or lower hazard level.This allows the user to continue machining even though they have already reached a low hazard level by signaling to the user that they should perform the machining with increased caution, reduced speed, or the like, to avoid moving from the lower hazard level to a higher hazard level, which would then trigger a safety measure to abort the machining operation. For example, the first safety measure can consist of a warning signal, such as an acoustic or visual warning signal or a slight reduction in the movement speed of the component, which gives the user a corresponding signal without interrupting the machining of the workpiece.Only with the second safety measure does a processing-interrupting measure take place, such as completely stopping the movement of the component or moving the component to a safe position.

[0045] It is even more preferred if the control device is arranged on the headgear, and the headgear further comprises a signal transmission unit for wireless signal transmission and is signal-coupled to the safety measure device by means of this signal transmission unit. With such a signal transmission unit, the headgear can be comfortably worn by the user, and the data determined by the control device on the headgear, and in particular the data content for triggering a safety measure, can be transmitted to the safety measure device.

[0046] Alternatively, it is provided that the control device is arranged on the machine tool, and the head mount further comprises a signal transmission unit for wireless signal transmission and is signal-coupled to the control device by means of this signal transmission unit. According to this embodiment, the control device is not arranged on the head mount, but on the machine tool, and in this case, the data acquired by the image capture device on the head mount is transmitted to the control device via the signal transmission unit.

[0047] In principle, in addition to these two possibilities for arranging the control device on the headrest or on the machine tool, another configuration is also advantageous in certain embodiments, in which the control device comprises a first control unit arranged on the headrest and a second control unit arranged on the machine tool, and the headrest further comprises a signal transmission unit for wireless signal transmission and by means of this signal transmission unit, the first and the second control units are signal-coupled, wherein the first control unit is designed to carry out a first part of the evaluation and to transmit a result determined therefrom to the second control unit, and the second control unit is designed,to perform a second part of the assessment based on this determined result and, depending on the assessment, to control the safety measure device to execute a safety measure. The assessment of the situation captured by the image capture device for a potential hazardous condition is carried out by a first control unit of a head mount and a second control unit on the machine tool. Such a division of the assessment allows those parts of the assessment to be carried out at the head mount that lead to a reduction in the data to be transmitted, thus enabling an efficient assessment to be carried out in real time.

[0048] It is further preferred if the headgear is designed as a pair of glasses and is configured to be used as protective goggles against mechanical eye injuries and / or to compensate for a visual impairment of the user. According to this embodiment, the data glasses fulfill additional functions that are necessary for the user personally or in certain work situations. Thus, the data glasses can be designed as approved protective goggles against eye injuries or they can be provided with corrective lenses to compensate for the user's personal visual impairment.

[0049] It is even further preferred if the image capture device on the data glasses is designed to capture images with depth information, in particular if the image capture device is designed to capture runtime information on image content or if the image capture device is designed to determine depth information from two images captured at a different time and with different recording directions based on an image evaluation of the position of detected objects relative to one another or if the image capture device comprises a first and a second image capture unit which are arranged at a distance from one another, for example are fastened to the head mount on the left and right sides of the user's head, and is designed to determine depth information from a stereoscopic image evaluation of simultaneously captured images of the first and second image evaluation unit.

[0050] According to this embodiment, the image capture device is designed such that it captures depth information about the objects captured in an image, thereby making it possible to determine the distance of these objects from the image capture device. This depth information can be provided point by point for each captured pixel or object by object. In principle, various configurations for capturing depth information of this type are possible, for example based on propagation time information of the signal from an object to the image capture device, or by capturing two images offset in time with a single image capture device and thereby determining depth information based on a comparison of objects that were captured in both images but which have a different position due to a movement of the image capture device between the two offset images.Furthermore, stereoscopic depth information can also be determined if two spaced-apart image acquisition units are arranged on the head mount, which have an at least partially overlapping image acquisition area and form the image acquisition device. Based on an object that is simultaneously captured by both image acquisition units, depth information can then be stereoscopically calculated from the angular position of the object in each of the two image acquisition areas.

[0051] It is even further preferred if the headgear further comprises an image output device for outputting image and text information to one or both eyes of the user wearing the headgear, in particular by means of

[0052] Displaying the image and text information on a screen, or

[0053] Projection of image and text information onto the retina of one or both eyes of the user.

[0054] According to this type of training, the headgear is also equipped to output an image that can be seen by the user, for example, via a screen mounted on the headgear or by projecting it onto the retinas of both eyes. This allows, on the one hand, simple or differentiated warning signals to be output to the user via the headgear. On the other hand, additional information not related to a hazardous situation can be displayed to the user via the image output device.In this case, it is particularly preferred if the headrest has a data interface for data transmission, in particular a data transmission unit for wireless data transmission, and is designed to receive image and / or text information via the data interface and to display it on the image output device, which includes a sequence of predetermined work processes for machining a workpiece, a representation of predetermined alignments and / or movements of a tool or a workpiece for carrying out a machining step, a designation of machined workpieces before and / or after machining, wherein the image or text information is preferably displayed on the basis of the image capture with the image capture device and an image analysis carried out therefrom to determine the position of the tool or the workpiece in an area that is assigned to the tool or the workpiece in the user's field of vision.This embodiment also uses the head mount for the targeted, location-specific output of information to the user that is helpful for machining a workpiece. For example, a workpiece on which several machining steps must be performed with the machine tool can be displayed to the user via the image output device on the head mount with regard to the necessary alignments and movements of the workpiece or tool, and a sequence of the machining steps to be carried out one after the other can be displayed as predetermined work processes. Furthermore, workpieces that are created in this way can be labeled accordingly to the user via the image output device on the head mount, for example as finished parts that the user should specifically deposit, or as intermediate finished parts that still require further machining, or as offcuts.

[0055] This information can be provided in image or text form, with the image or text information preferably being displayed to the user in such a way that they can see it in the respective workpiece in the manner of augmented reality, allowing them to clearly identify it for processing. It should be understood that in an alternative embodiment, these spatially resolved display functions of the image output device on the head mount can also be implemented without the image capture device arranged on the head mount.

[0056] A further aspect of the invention is a machine tool having a safety device of the type described above. This machine tool can be a stationary machine tool or a hand-held tool as described above. It is particularly preferred if the machine tool is a panel saw and the safety measure device is designed to brake the rotation of a circular saw blade of the panel saw and / or to move the circular saw blade of the panel saw transversely to its axis of rotation into a non-hazardous position. The safety device according to the invention is suitable for various machine tools, including in particular circular saws, from which a potential hazard for a user's hand emanates from the circular saw blade and where the user regularly has his or her gaze directed at this hazardous area around the circular saw blade during processing.The safety measure for a circular saw can be that the rotation of the circular saw blade is stopped and thereby a cut is prevented or that the circular saw blade of the circular saw, which protrudes from a workpiece support surface, is moved (e.g. lowered downwards) in order to lie under this workpiece support surface or within a protective shield and is therefore no longer accessible to the hand of a user.

[0057] Alternatively, the machine tool can also be designed as a hand tool and the control device is preferably designed to determine an orientation and position of the hand tool in relation to a body part of the user based on an image evaluation of an image captured by the image capture device and to evaluate a potential hazardous situation of the body part based on the orientation and position, and wherein further preferably the head support has a data interface, in particular a wireless data transmission device and is designed to control the safety measure device for carrying out a safety measure depending on the evaluation via the data interface.This design makes it possible to monitor hand tools for potential hazardous conditions, whereby the control device additionally takes into account the fact that the hand tool is guided by the user and can therefore be arranged in very different orientations and distances from the user during image evaluation.

[0058] A further aspect of the invention is a headgear for a safety device of the type described above, which is characterized by an image capture device that is aligned to carry out an image capture in the field of vision of the wearer of the headgear, and preferably further comprising a control device that is signal-coupled to the image capture device and is designed to carry out an assessment of a potential hazardous state detected by the image capture device on the basis of predetermined criteria, wherein further preferably the headgear has a data interface, in particular a wireless data transmission device, and is designed to control the safety measure device to carry out a safety measure depending on the assessment via the data interface.

[0059] The headgear according to the invention is particularly suitable for use with a safety device or a machine tool of the type described above and can therefore be developed with regard to the control device and its design as well as the image capture device arranged thereon in such a way as was previously described for the safety device according to the invention with the headgear contained therein.

[0060] The invention therefore also relates to the use of a head holder with an image capture device arranged thereon for detecting a potential hazardous condition on machine tools, wherein this includes machine tools of the type described above, i.e. stationary machine tools or hand tools.

[0061] Finally, a further aspect of the invention is a method for preventing injuries on machine tools, comprising

[0062] - Detecting a potential hazardous condition for a body part of a machine tool user caused by an injury-risk component of the machine tool by means of a detection device,

[0063] - Carrying out a safety measure by which a hazardous situation for the user of the machine tool caused by a component of the machine tool is reduced or avoided by means of a safety measure device,

[0064] - Evaluating a potential hazard condition detected by the detection device based on predetermined criteria by means of a control device which is signal-linked to the detection device and the safety measure device, and

[0065] - controlling the safety measure device to execute a safety measure depending on the assessment, characterized in that the detection of the potential hazardous condition is carried out by means of an image capture device arranged on a headgear, which is aligned to capture an image in the field of vision of the wearer of the headgear, and the assessment is carried out using images captured by the image capture device. With regard to this method for preventing injuries on machine tools, it should be understood that this proceeds according to the principle as previously described for the safety device according to the invention and the method can accordingly also be developed in the manner previously explained for the safety device. The method can preferably be carried out with a safety device or a machine tool of the type described above.

[0066] A preferred embodiment of the invention is explained with reference to the accompanying figures. They show:

[0067] Fig. 1 is a schematic perspective view of a head mount according to the invention designed as data glasses, and

[0068] Fig. 2 is a schematic representation of a visualization of a machining situation on a machine tool equipped with the safety device according to the invention, carried out by an image output device on the head holder.

[0069] As can initially be seen from Fig. 1, data glasses for use according to the invention comprise a spectacle frame 1, which basically consists in a known manner of two temples 1a, 1b and the frame for the two lenses. A video camera 2a, 2b is arranged on the right temple 1a and the left temple 1b of the spectacle frame 1, which video cameras form the image capture device. These video cameras are aligned with their image recording direction approximately in the longitudinal axis of the temples of the glasses, as indicated by the image angle 3a, 3b in the figure, and thus capture an image area in which the user's field of vision 3c lies. The two video cameras 2a, 2b are connected to a control device 5 via data lines 4a, 4b.The control device 5 comprises a transmission unit 6 with a transmission antenna 6a in order to wirelessly transmit data, which were calculated in the control device from the image data of the two video cameras 2a, 2b, to a security measure device.

[0070] Projection screens 7a, 7b are embedded in the frame of the glasses, allowing an image to be projected onto the user's retina. These screens 7a, 7b are transparent, allowing the user to see through them, and the projected image is superimposed onto the real surroundings seen through the lenses to create an augmented reality. The projection can therefore be used to specifically indicate objects the user sees through the lenses, or to overlay warnings onto the real image of the surroundings.

[0071] Fig. 2 shows an exemplary superimposed image situation implemented as augmented reality, which a user sees through the data glasses according to the invention. It can be seen that the user is currently feeding a workpiece 20 with his hand 40 towards a circular saw blade 10 of a panel saw in order to make a cut on the workpiece. The cutting line in the workpiece is projected onto the workpiece 20 as a broken line 20a by being displayed via the data glasses. Furthermore, two pieces of information 102 and 103 are depicted on the workpiece, which indicate to the user for further handling the two workpieces created after separation by means of the circular saw blade. These pieces of information 102, 103 can, for example, be a designation of a finished part, such as a door, floor or the like, or can indicate to the user that this part still requires further processing or is a leftover piece.

[0072] The user continues to see his or her own hand 40 through the lens, with which he or she is guiding the workpiece 20. Furthermore, a workpiece 21 is depicted on the machine tool table 30, onto which a further designation 101 is projected by means of the data glasses. This workpiece is intended for subsequent processing and is marked accordingly by the designation 101.

[0073] In the machining situation depicted in Fig. 2, the user is slowly guiding the workpiece toward the circular saw blade 10 using their hand, and the control device has determined both the movement speed and the movement direction and acceleration of the hand 40 in the captured image by evaluating several sequential images. Furthermore, based on the images captured by the video cameras 2a, 2b, the control device has detected the circular saw blade 10 and a marking 10a arranged thereon by image analysis, which contains information about the saw blade diameter and saw blade weight. Therefore, based on the direction of movement of the hand and the movement speed of the hand, it can be determined whether the user's hand is at risk of injury from contact with the saw blade if the movement is continued, and at what point in time this contact would occur if the hand movement were to continue.

[0074] In the present case, the control device has further determined that the hand 40 is currently being moved without further acceleration at a slow speed, but precisely in the direction of the circular saw blade, and therefore a potentially hazardous situation with a still low risk level exists. The control device therefore triggers a safety measure, which in the present case consists in providing the circular saw blade with a red colored marking 100 via the image projection of the data glasses. This colored marking 100 can be displayed as constantly illuminated or flashing, with the flashing frequency preferably increasing as the hand 40 approaches the circular saw blade, thereby signaling the increase in the hazardous state.

[0075] By continuously analyzing the image captured by the video cameras 2a, 2b, the control device can then determine whether the user changes the position and movement of their hand due to this initial safety measure, thereby removing their hand from the potentially hazardous situation. If the user does so, for example, by removing their hand from the workpiece and continuing to push the workpiece forward with a push stick, the initial safety measure can be canceled, and the red glow or flashing of the circular saw blade can be stopped by the projection via the data glasses.

[0076] However, if the user does not change their hand position in a way that resolves the potentially hazardous situation, a situation arises in which the hand has approached a critical distance from the circular saw blade. This critical distance can be achieved by approaching the hand at a constant speed until it reaches a critical distance. If the control device detects, based on the real-time images from the video cameras, that the hand is accelerating and thus increasing its speed, the distance at which a second safety measure is triggered can also increase.If the distance calculated as the hazard distance for a second safety measure based on the respective direction of movement, speed of movement, and, if applicable, acceleration of the hand relative to the circular saw blade is reached, the control device triggers a second safety measure, which could, for example, consist of reducing the speed of the circular saw blade by 50%. This second safety measure is very clearly perceived by the user and, while it does not yet lead to the interruption of processing, often prompts the user to immediately change their working method in order to resolve the potentially hazardous situation and to be able to continue processing the workpiece as normal.If the user does not react to this second safety measure and continues to approach the circular saw blade, a third safety measure is triggered when a third safety distance is exceeded. This third safety measure consists of a rapid lowering of the circular saw blade below the workpiece support surface 30. This rapid lowering interrupts the machining process on the workpiece and lowers the circular saw blade through a saw blade slot in the workpiece support surface 30 of the machine tool so that the user's hand can no longer touch the saw blade, thus preventing injury.

[0077] List of reference symbols:

[0078] 1 pair of glasses frames

[0079] 1a, 1b bracket

[0080] 2a, 2b video camera

[0081] 3a, 3b Angle of view

[0082] 3c Field of view

[0083] 4a, 4b data lines

[0084] 5 Control device

[0085] 6 Transmission unit

[0086] 6a Transmitting antenna

[0087] 7a, 7b Projection screens

[0088] 10 circular saw blades

[0089] 10a Marking by image analysis

[0090] 20, 21 Workpiece

[0091] 20a broken line

[0092] 30 Machine tool table / tool ​​support surface

[0093] 40 hands

[0094] 100 color markings

[0095] 101 Designation using data glasses

[0096] 102, 103 two details about the workpiece

Claims

Claims:

1. Safety device for a machine tool, comprising - a detection device designed to detect a potential hazard to a body part of a user of the machine tool caused by a component of the machine tool that poses a risk of injury - a safety device designed to perform a safety measure by which a hazardous condition of the user of the machine tool is reduced or avoided by a component of the machine tool, - a control device which is coupled and configured with the detection device and the safety measure device via signal technology in order to perform an evaluation of a potential hazard state detected by the detection device based on predetermined criteria and, depending on the evaluation, to control the safety measure device to execute a safety measure, characterized in that the detection device comprises a head mount for attachment to the user's head and an image capture device attached to the head mount, which is oriented to perform image capture in the user's field of vision, and the control device is configured to perform the evaluation based on images captured by the image capture device.

2. Safety device according to claim 1, characterized in that the control device is designed to recognize the body part of the user and the component of the machine tool in the image captured by the image acquisition device by means of an image evaluation and to trigger the safety measure depending on this recognition.

3. Safety device according to claim 1 or 2, characterized in that the control device is designed to determine a distance, or an approach speed or an approach acceleration between the body part and the component by means of image evaluation as hazard parameters and to trigger the safety measure depending on one or more of these hazard parameters.

4. Safety device according to claim 2 or 3, characterized in that the control device is designed to determine, by means of image evaluation as hazard parameters, a distance of the body part from the image acquisition device, or a distance of the component from the image acquisition device, or a relative direction of movement of the component and body part to each other, or a relative direction of acceleration of the component and body part to each other, and to trigger the safety measure depending on one or more of these hazard parameters.

5. Safety device according to one of the preceding claims, characterized in that the control device is designed to determine the position, speed and / or acceleration of the component of the machine tool by means of an image evaluation based on data processing with artificial intelligence used in the image evaluation, or an image-capable marking on the tool, or an input from the operator, or position data received from a transmitting device on / in the component.

6. Safety device according to one of the preceding claims, characterized in that the image acquisition device or the control device is configured to perform image evaluation in order to determine a section of the captured image that corresponds to a predetermined field of vision or a predetermined section of the field of vision of a user wearing the data glasses, in particular a section corresponding to the fovea of ​​the field of vision, and the control device is configured to determine, by means of image evaluation, whether the component is located within the image section and to control the safety measure device to execute a safety measure if the component is not located within the image section.

7. Safety device according to claim 6, characterized in that a device for eye tracking is attached to the head mount and that the image section to be evaluated by the image evaluation is determined depending on the direction of gaze of the user determined by means of the eye tracking.

8. Safety device according to one of the preceding claims, characterized in that the safety measure A reduction in the movement speed of the component, Moving the component to a position with less risk, Shielding of the component, and / or This includes activating a warning signal in a signal output device located on the data glasses.

9. Safety device according to one of the preceding claims, characterized in that the control device is designed to distinguish between a low and a higher hazard level and to execute a first safety measure, in particular a warning signal, at the low hazard level and to execute a second safety measure, which differs from the first safety measure, at the higher hazard level.

10. Safety device according to one of the preceding claims, characterized in that the control device is arranged on the head mount and the head mount further comprises a signal transmission unit for wireless signal transmission and is coupled to the safety measure device by means of this signal transmission unit.

11. Safety device according to one of the preceding claims 1-9, characterized in that the control device is arranged on the machine tool and the head holder further comprises a signal transmission unit for wireless signal transmission and is coupled to the control device by means of this signal transmission unit.

12. Safety device according to one of the preceding claims 1-9, characterized in that the control device comprises a first control unit arranged on the head mount and a second control unit arranged on the machine tool, and the head mount further comprises a signal transmission unit for wireless signal transmission and the first and second control units are coupled by means of this signal transmission unit, wherein the first control unit is designed to perform a first part of the evaluation and transmit a result obtained from it to the second control unit, and the second control unit is designed to perform a second part of the evaluation based on this result obtained and, depending on the evaluation, to control the safety measure device to execute a safety measure.

13. Safety device according to one of the preceding claims, characterized in that the head support is designed as glasses and is configured to be used as protective eyewear against mechanical injuries to the eye and / or to compensate for a visual impairment of the user.

14. Safety device according to one of the preceding claims, characterized in that the image acquisition device is configured to capture images with depth information, in particular by the image acquisition device being configured to capture runtime information on image content, or by the image acquisition device being configured to determine depth information from two temporally offset images with different recording directions by means of an image evaluation of the position of detected objects relative to each other, or by the image acquisition device comprising a first and a second image acquisition unit which are arranged at a distance from each other, for example attached to the head support on the left and right sides of the user's head, and being configured to determine depth information from a stereoscopic image evaluation of simultaneously captured images of the first and second image evaluation unit.

15. Safety device according to one of the preceding claims, characterized in that the head mount further comprises an image output device for outputting image and text information to one or both eyes of the user wearing the head mount, in particular by means of Display of image and text information on a screen, or Projection of image and text information onto the retina of one or both of the user's eyes.

16. Safety device according to the preceding claim, characterized in that the head mount has a data interface for data transmission, in particular a data transmission unit for wireless data transmission, and is designed to receive image and / or text information via the data interface and to reproduce it on the image output device, which A sequence of predetermined work processes for machining a workpiece A representation of predetermined orientations and / or movements of a tool or workpiece for carrying out a machining step. A designation of machined workpieces before and / or after machining includes, preferably, the image or text information based on image acquisition with the image acquisition device and an image evaluation carried out therefrom to determine the position of the tool or the workpiece in an area that is assigned to the tool or the workpiece in the user's field of vision.

17. Machine tool comprising a safety device according to one of the preceding claims.

18. Machine tool according to claim 17, characterized in that the machine tool is a sliding table saw and the safety device is designed to brake the rotation of a circular saw blade of the sliding table saw and / or to move the circular saw blade of the sliding table saw transversely to its axis of rotation into a non-hazardous position.

19. Machine tool according to claim 17, characterized in that the machine tool is a hand tool and the control device is preferably designed to determine, on the basis of an image evaluation of an image captured by the image acquisition device, an orientation and position of the hand tool in relation to a body part of the user and, on the basis of the orientation and position, to assess a potential hazard situation of the body part, and wherein the data glasses preferably have a data interface, in particular a wireless data transmission device, and are designed to control the safety measure device to execute a safety measure depending on the assessment via the data interface.

20. Head mount for a safety device according to one of the preceding claims, characterized by an image capture device which is oriented to perform image capture in the direction of view of the wearer of the data glasses, and preferably further comprising a control device (must include a mobile phone) which is coupled to the image capture device via a signal and is configured to perform an evaluation of a potential hazard state detected by the image capture device based on predetermined criteria, wherein the head mount preferably has a data interface, in particular a wireless data transmission device, and is configured to control the safety measure device to execute a safety measure depending on the evaluation via the data interface.

21. Head support according to claim 20, characterized in that the head support is further developed according to the features of the head support according to the safety device according to one of the preceding claims 1-19.

22. Methods for preventing injuries on machine tools, comprising - Detecting a potential hazard to a body part of a user of the machine tool caused by a component of the machine tool that poses a risk of injury, using a detection device, - Implementing a safety measure by which a hazardous condition for the user of the machine tool is reduced or avoided by means of a safety device, - Evaluating a potential hazard situation detected by the detection device based on predetermined criteria using a control device Z-equipment that is signal-technically coupled to the detection device and the safety measure device, and - Controlling the safety measure device to execute a safety measure depending on the assessment, characterized in that the detection of the potential hazard state is carried out by means of an image capture device arranged on a head mount, which is aligned to perform image capture in the field of vision of the wearer of the head mount, and the assessment is carried out on the basis of images captured by the image capture device.

Images