DE102023123903B4 - Monitoring device and method for optical monitoring of the surfaces of an object, in particular a sauna heater - Google Patents

Abstract

Monitoring device (2) for optical monitoring of surfaces (10) of an object (1) on which objects (4) can be placed, wherein the monitoring device (2) comprises:
- at least one optical sensor (20) which is/are configured to optically detect at least partial areas of a profile of the surface (10), and
- a processing device which is in communication connection with the at least one optical sensor (20) and is configured to determine or store at least one reference profile of the surface (10) as a two-dimensional height profile (11) of the surface (10), and to process measured values acquired during optical monitoring in such a way that it detects a deviation of a currently measured two-dimensional height profile (11) from the reference profile and, depending on the detected deviation, outputs a signal to communicate that an object (4) is located on the surface (10) and/or to prevent the release of an operation of the object (1), in particular in the case of a remote activation request, wherein, for the purpose of initializing the monitoring device (2), information regarding the surface structure of the two-dimensional height profile (11) is provided to the processing device, which it processes in such a way that a reference profile of the surface (10) is generated from it.

Description

The invention relates to a monitoring device for the optical monitoring of surfaces of an object on which objects can be placed. In particular, the invention aims to monitor the surfaces of sauna heaters in order to check whether objects are still on the heater when it is switched on (remotely). This reduces the risk of fire. Other surfaces, such as shelves, can also be monitored.

Heated rooms such as saunas, sanariums, or steam rooms are widespread. These rooms are heated by heat sources such as a stove, which is usually topped with stones because these provide good heat retention and a slow release of heat into the room. Hereinafter, such rooms will be referred to as saunas. To start the heating process and control the temperature and, if applicable, the humidity in the room, a control and regulation device is used. This device receives an indoor temperature reading from temperature sensors located within the room and uses this information to control the heat source.

Remotely switching on heat sources such as sauna heaters is currently more complex, as it must be ensured that no objects are on the heat source, since these could catch fire due to the high temperatures. In the DE 199 54075 C1 A safety switching device for activating the heating of a heated room is proposed, which includes remote activation. However, this remote activation still relies on a person directly granting permission at the sauna. In the DE 199 54075 C1 A key switch is provided for this purpose, which communicates with the remote activation system via a network connection. The oven cannot be switched on without activating the key switch on site.

In many areas, there are storage areas for materials, packages, processed workpieces, etc., for which active remote monitoring is possible, but there is still room for improvement.

From the DE 10 2007 005 603 A1 A safety-related method for commissioning heating devices for saunas, infrared cabins, steam baths, or the like is known, in which a safety device monitors the commissioning process. This monitoring provides that if the commissioning process deviates from the operating specifications, the heating device is switched off by means of a control unit of the safety device, wherein at least one temperature sensing element measures the temperature during heating to control the control unit, and the control unit signals a warning signal in the event of a control unit failure.

The EP 3 746 739 B1 describes a device for identifying equipment, in particular metallurgical vessels, in a metallurgical industrial plant, comprising an identification tag attached to the equipment, a receiving device and an evaluation unit which recognizes the equipment on the basis of the identification tag, the identification tag being a three-dimensional identification tag, in particular a perforated plate or a plate with three-dimensional patterns.

The EP 3 791 849 A1 Disclosing a method for detecting objects on a sauna heater, the method comprises the following steps: a) creating a normal target heat radiation curve by means of measurements over a period of time and storing the heat radiation curve in a memory of a control unit, b) monitoring the heat radiation measurements from a sauna heater over a corresponding period of time using a first sensor, c) comparing the monitored heat radiation with values in the normally set heat radiation curve by software in the control unit, d) the control unit switches off the sauna heater if a deviation from a normal heat radiation curve is detected, and if there is no deviation, the normally set heat radiation curve is updated with the monitored heat radiation measurements.

One objective of this invention is to provide an automated monitoring capability for the surfaces of an object on which objects can be placed.

This problem is solved according to the invention by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims.

A monitoring device for the optical monitoring of surfaces of an object on which objects can be placed is proposed, wherein the monitoring device comprises: at least one optical sensor which is/are configured to optically detect at least partial areas of a profile of the surface, and a processing device which is in communication with the at least one optical sensor and is configured to generate at least one reference profile as a two-dimensional height profile of the surface. to determine or store the surface of the surface, and to process measured values acquired during optical monitoring in such a way that it detects a deviation of a currently measured two-dimensional height profile from the reference profile and, depending on the detected deviation, outputs a signal to communicate that an object is located on the surface and/or to prevent the release of an operation of the object, particularly in the case of a remote activation request, wherein, for the initialization of the monitoring device, information regarding the surface structure of the two-dimensional height profile is provided to the processing device, which it processes in such a way that a reference profile of the surface is generated from it.

In one embodiment, the processing device is configured to output the signal only after a predetermined time.

In one embodiment, the output signal is provided to be an acoustic signal and/or an optical signal and/or a haptic signal.

In one embodiment, the object is a device that is powered by energy, wherein the output signal is a control signal to prevent or abort activation of the object which has the surface, wherein the output control signal withdraws a release to activate the device.

In one embodiment, the optical sensor is designed to continuously or intermittently acquire the measured values.

In an unclaimed embodiment, it is provided that, for the initialization of the monitoring device, the optical sensor determines a profile of the surface as a reference surface, or wherein a profile of the surface is stored as a reference surface in the processing device.

In one embodiment, the monitoring device is provided to have a control element, the operation of which enables the detection of the surface's reference profile.

Furthermore, a system consisting of a sauna heater and a monitoring device is provided, wherein the monitoring device for monitoring a surface of the sauna heater is arranged and configured in such a way that, in the event that it receives a remotely controlled switch-on signal as an activation request, and the processing device detects a deviation of a currently measured two-dimensional height profile from the reference profile and an exceedance of a predetermined limit value, it outputs a signal in such a way that switching on the sauna heater is prevented.

Furthermore, a sauna is provided, comprising the monitoring device or the system consisting of a sauna heater and monitoring device.

Furthermore, a method for the optical monitoring of the surfaces of an object on which objects can be placed is provided, using a monitoring device. In an initialization step, the monitoring device provides the processing device with information regarding the surface structure of the two-dimensional height profile. The processing device then processes this information to generate a reference profile of the surface as a two-dimensional height profile, which is stored by the processing device. Subsequently, upon a switch-on signal, the current surface is at least partially scanned by means of at least one optical sensor to determine a current two-dimensional height profile of the surface. If a deviation of the currently measured two-dimensional height profile from the reference profile is detected, such that a limit value is exceeded, a signal is output to prevent operation of the object and/or to indicate that an object is located on the surface.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures in the drawing, which shows details of the invention, and from the claims. The individual features can be implemented individually or in any combination in a variant of the invention.

Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawing.

1 Figure 1 shows a representation of a monitoring device arranged above an object according to an embodiment of the present invention.

The invention provides a monitoring device 2 for the optical monitoring of surfaces 10 of an object 1. It can be provided that no additional objects may be placed on the surfaces 10 in certain situations, which is particularly useful for sauna heaters. This is necessary to enable remote, i.e., unattended, switching on. Remote switching is understood to mean any switching on where there is no direct line of sight to the surface(s) 10 of the object 1, i.e., where they are not monitored during switching on. However, monitoring of the surface 10 to determine whether an object 4 has been placed on it is also possible. To achieve this, the monitoring device 2 has at least one optical sensor 20, which is arranged above the surface 10 of the object 1. It can be arranged directly above (perpendicularly), e.g., on a ceiling above the surface 10, or at an angle to the surface 10, e.g., on a wall of a room, as long as its field of view covers the surface 10 to be monitored or the part thereof to be monitored. In the case of several optical sensors 20, it is advantageous to arrange them at different angles to the surface 10 of the object 1 to allow for different viewing angles. This makes it easier to scan the entire surface. 1 The optical sensor 20 covers the entire surface 10 of the object 1, as indicated by the lines pointing towards the corners. The optical sensor 20 can be positioned near the object 1, i.e., at a distance from it. The optical sensor 20 can be attached to a ceiling, a wall, a tripod, or another suitable mounting.

The optical sensor 20 preferably uses a scanning method and is, for example, designed as an ultrasonic sensor, a ToF sensor (ToF = Time-of-Flight, distance measurement using the time-of-flight method), or a LiDAR sensor. Furthermore, more than one optical sensor 20 can be provided to cover a correspondingly large surface 10 or to provide high resolution. The optical sensor 20 serves to measure several individual measurement points (indicated by the dashed arrows in 1 (indicated) to capture on the surface 10, thereby generating a matrix of measurement points from which a two-dimensional profile 11 of the surface 10, i.e., a surface structure/two-dimensional relief of the surface, can be created by a suitable processing device. The number of measurement points and the distance between the measurement points, i.e., the resolution of the measurement, depend on the optical sensor 20 used and the application, i.e., how accurately the profile must be captured in order to be able to detect objects 4 placed on it.

The monitoring device 2 also includes a processing unit, for example a CPU, which serves to process the measurement points detected by the optical sensor 20, which may also include filtering, and to generate the two-dimensional height profile 11 of the surface 10. It also serves to control the monitoring, i.e., when the optical sensor 20 is active and when it is inactive. The optical sensor 20 is active when an activation request, e.g., a switch-on signal, is sent via a remote control 5 to the control unit of the object 1, e.g., a sauna heater, and thus to the monitoring device 2. As soon as a switch-on signal is received, the optical sensor 20 is activated and starts monitoring, i.e., scanning the surface 10.

Before this can happen, however, at least one reference profile is required for comparison. For the sake of simplicity, only "one" reference profile will be mentioned in the following, but this does not preclude the use of multiple reference profiles. A reference profile is the two-dimensional height profile 11 of the surface 10, which exists in a predefined state of the object 1, e.g., a state after initial installation or a state defined as safe, and which is to trigger an action when this state changes. It is, for example, the profile that is determined for the initialization of the monitoring device 2. The reference profile can be acquired by the optical sensor 20, or it can receive the reference profile as a complete data set for immediate use or as an incomplete data set from which the processing unit of the monitoring device 2 must still calculate the reference profile. In any case, the reference profile is stored in the processing unit, advantageously persistently, e.g., in non-volatile memory.

The reference profile can only be generated by activating the initialization directly at the monitoring device 2, e.g., by pressing a control element such as a button. This ensures that the surface 10 is in the state that is to be used as the reference value.

The current two-dimensional height profile 11 of the surface 10 can either be acquired by the optical sensor 20 by scanning the surface 20 at least once, and the processing unit then calculates the current two-dimensional height profile 11 of the surface 10 and defines it as a reference profile. Alternatively, if the surface structure (two-dimensional height profile 11) of an object 10 is known, this can be provided to the monitoring device 2, more precisely its processing unit, as a directly processable data set, e.g., via a suitable wireless or wired interface. Alternatively, information regarding the surface structure (of the two-dimensional height profile) can be provided to the processing unit. fils 11) are provided, which they themselves process in such a way that a reference profile is generated from it. Such information can be the signal propagation time between optical sensor 20 and surface 10, the reflection behavior of the surface 10, the color of the surface 10, the material of the surface 10, the surface texture, the distance between optical sensor 20 and surface 10 per measuring point, the position of the optical sensor(s) 20 (in all spatial directions) or a combination thereof.

Once the reference profile is known, monitoring can begin. For this purpose, the optical sensor 20 scans the surface 10 at least once to determine the current two-dimensional height profile 11 and thus the two-dimensional height profile 11 of the surface to be compared with the reference profile. Advantageously, the optical sensor 20 scans the surface 10 multiple times to reduce measurement errors. The scanning can be continuous or in intervals, i.e., with pauses between scans. Scanning means that a measurement is taken once at each measuring point and the result is transmitted to the processing unit for further processing. Monitoring of the surface continues until a shutdown condition is met or the monitoring unit receives a shutdown signal. The duration of the monitoring depends on the application. Shutdown conditions can be specified in a separate control unit 3, which communicates with the monitoring unit 2, or directly in the monitoring unit 2 if it is part of the control unit 3. The monitoring device 2 can also be switched off directly, e.g., by a user, or remotely, i.e., with an external remote control 5, depending on the application. The control unit 3 can be part of the external remote control 5, as shown in 1 indicated, or formed as a separate unit or be part of the monitoring device 2.

Monitoring is carried out by the processing unit comparing the at least one stored reference profile with the measured two-dimensional height profile 11 and evaluating whether a limit value of a permissible deviation is exceeded or not reached in the measured two-dimensional height profile 11 (depending on the measurement principle). If this is the case, it can be assumed that an object 4 is located on the surface 10 of the object 1.

In a simple case, a reference profile can be the sum of the measured distances of the individual measuring points from the surface 10. If this sum changes during the current measurement (monitoring) and exceeds or falls below a predefined limit (depending on the measurement principle), then it can be assumed that an object 4 is located on the surface 10. The measurement can be refined as desired by the type and number of optical sensors 20 and computational processing, for example, to detect a more precise position, shape, and size of the object 4, or a color difference from the reference profile.

If a predefined limit is detected as being exceeded or fallen below, the processing unit can output a signal. This signal can be sent to an external device, such as remote control 5, which converts it and outputs it as an alarm and/or a control signal. Naturally, a signal can also be output directly at the monitoring unit 2. This signal can be an activation signal for a warning light or a warning tone. Such an alarm signal can be an audible warning, for example, a tone; a visual warning, for example, by means of a two-color (green/red) light or a display showing text or an image; a haptic warning, for example, vibrations from remote control 5, which trigger the activation of the monitoring unit 2; or a combination thereof. Furthermore, the signal can be a control signal to prevent or abort the activation of object 1, which has surface 10. Such an object 1 could be, for example, a sauna heater or a machine for processing workpieces. The control signal revokes the authorization to activate object 1, which is usually achieved by disconnecting it from the power supply (energy).

In one embodiment, the signal is output with a time delay in order to enable and evaluate multiple samples (i.e., measurement series) of the optical sensor 20, in order to reduce measurement errors and thus incorrect signal outputs, and to ignore short-term impairments of the measurement or evaluation.

In one embodiment, it is provided that if an object 4 is detected on the surface 10, reactivation can only occur again when an unlocking unit located in the area of the monitoring device 2, and thus of the object 1, is actuated, e.g., by pressing a button. This ensures that a person on site cannot be disturbed. convinced that no object 4 (anymore) is located on surface 10.

In one implementation, it can be provided that predefined areas of the measured surface 10, i.e., the reference profile, are excluded (masked) from subsequent monitoring. Masking allows, for example, the exclusion of corners detected by the measurement on round ovens, even if these corners are not relevant. Masking could also be used to hide non-critical areas, so that a detected object (deviation from the reference profile) no longer triggers a shutdown (withdrawal of authorization) and/or an alarm.

The invention is described in more detail below with reference to a preferred embodiment in which a surface 10 of a sauna heater, referred to as object 1, is monitored. The sauna heater is used in a heated room, hereinafter referred to as a sauna. The term "sauna" encompasses all rooms that can be heated with a sauna heater, including the classic Finnish sauna, saunas with lower or higher temperatures and lower or higher humidity, steam baths, etc.

In saunas, it is mandatory that the sauna heater may only be switched on after a person has physically verified that, among other things, no object 4 is on the surface 10 of the sauna heater. This is to prevent fires caused by objects 4 that are on the heater and could ignite after it is switched on and heats up. Such objects 4 can be wooden buckets, towels, wooden spoons, cloths (including cleaning cloths), etc., which are not normally on the sauna heater, especially the very hot stones, during operation. The proposed monitoring device 2 can also reliably detect remotely whether a foreign object 4 is on the surface 10 of the heater, i.e., whether the detected profile deviates from the reference profile. If this is the case, authorization to operate the heater can be withdrawn, i.e., the heater can be automatically prevented from being switched on, or the heater can be automatically switched off. Therefore, it is no longer necessary for a person to be physically near the oven to switch it on and monitor it.

As previously described, the monitoring device 2 determines at least one reference profile for the oven during installation or in the event of any modification to the oven, e.g., the addition or removal of stones or fragrance containers, etc. This profile is compared with a measured, current two-dimensional height profile 11 when the oven is remotely switched on. An assessment is then made as to whether the difference between the two-dimensional height profiles 11 exceeds or falls below a limit value. Thus, it is possible to detect, without the presence of a person, whether an object 4 is located on the surface 10 of the oven. If an object 4 is detected, the monitoring device 2 can send a signal to the oven's control unit, causing it to switch off (or prevent it from being switched on). Simultaneously, a signal can also be sent to, for example, the remote control, which then processes this signal as described above and is used to remotely switch on the oven. Such a remote control can be a separate panel, but also a user's mobile phone with a corresponding software interface and a so-called app. The monitoring device 2 can be part of the oven's control and regulation system, or a separate unit that communicates with the oven's control and regulation system.

This allows for remote monitoring of one or more sauna heaters, which also makes it possible to remotely switch on the sauna heater(s).

The described monitoring device 2 can be used not only to monitor the surfaces 10 of sauna heaters, but also to monitor other surfaces 10 on which objects 4 (including people or animals) can be placed, i.e., any type of surface. For example, table surfaces used for placing packages or other objects 4 can be monitored, and a signal can be issued if it is detected that an object 4 is on the table. Workbenches can also be monitored, and machines can be prevented from placing objects 4 on them if it is detected that an object 4 is already on the workbench. Furthermore, damage to objects 4, such as toilets, can be detected, e.g., if a toilet seat is missing, or if no object 4 (in the form of a person) has been detected in the toilet for an extended period of time.

The proposed monitoring device 2 can therefore create an initial reference profile for virtually any surface. During monitoring using the optical sensor 20, deviations of the measured surface profile from the reference profile can be detected. and appropriate measures – depending on the application – should be taken.

The advantage of the proposed monitoring device 2 is that it eliminates the need for a person to be physically present to verify whether the surface 10 of object 1 corresponds to the stored reference profile, i.e., whether it is usable or undamaged, depending on the application. Furthermore, no camera is required to monitor surface 10, which is desirable in certain applications.

The proposed invention enables remote monitoring of surfaces. This simplifies processes such as switching on sauna heaters or reducing the need for personal checks. A particular advantage is that the monitoring device 2 is remotely controllable, specifically switchable on and off. Naturally, a suitable interface is required for communication with a remote control 5 and/or a control unit 3.

Reference symbol list

1

Object, e.g. sauna stove

10

Surface area of 1

11

two-dimensional profile/relief of 10

2

Monitoring device

20

optical sensor

3

Control and regulating device

4

Object

5

remote control

Claims (9)

Monitoring device (2) for optically monitoring surfaces (10) of an object (1) on which objects (4) can be placed, wherein the monitoring device (2) comprises: - at least one optical sensor (20) configured to optically detect at least partial areas of a profile of the surface (10), and - a processing device that is in communication with the at least one optical sensor (20) and configured to determine or store at least one reference profile of the surface (10) as a two-dimensional height profile (11) of the surface (10), and to process measured values acquired during optical monitoring in such a way that it detects a deviation of a currently measured two-dimensional height profile (11) from the reference profile and, depending on the detected deviation, outputs a signal to communicate that an object (4) is located on the surface (10) and/or to prevent the object (1) from being enabled to operate, particularly in the case of a remote activation request, wherein the monitoring device (2) is initialized by The processing device is provided with information regarding the surface structure of the two-dimensional height profile (11), which it processes in such a way that a reference profile of the surface (10) is generated from it. Monitoring device (2) according to Claim 1 , wherein the processing device is configured to output the signal only after a predetermined time. Monitoring device (2) according to one of the preceding claims, wherein the output signal is an acoustic signal and/or an optical signal and/or a haptic signal. Monitoring device (2) according to one of the preceding claims, wherein the object (1) is a device which is powered by energy, wherein the output signal is a control signal to prevent or abort activation of the object (1) which has the surface (10), wherein the control signal withdraws the release to activate the device. Monitoring device (2) according to one of the preceding claims, wherein the optical sensor (20) is configured to perform the acquisition of the measured values continuously or at intervals. Monitoring device (2) according to one of the preceding claims, wherein the monitoring device (2) has an operating element by the operation of which the reference profile of the surface (10) is acquired. System comprising sauna heater and monitoring device (2) according to one of the preceding claims, wherein the monitoring device (2) for monitoring a surface (10) of the sauna heater is arranged and configured such that, in the event that it receives a remotely controlled switch-on signal as an activation request, and the processing device detects a deviation of a currently measured two-dimensional height profile (11) from the reference profile and an exceedance of a predetermined limit value, it outputs a signal such that switching on of the sauna heater is prevented. sauna, having the monitoring device (2) according to one of the Claims 1 until 6 or the system consisting of a sauna heater and monitoring device (2) according to Claim 7 . Method for optical monitoring of surfaces (10) of an object (1) on which objects (4) can be placed, by means of a monitoring device (2) according to one of the Claims 1 until 6 , wherein in an initialization step the monitoring device (2) is provided with information regarding the surface structure of the two-dimensional height profile (11), which it processes in such a way that a reference profile of the surface (10) is generated as a two-dimensional height profile (11) and stored by the processing device, and subsequently, upon a switch-on signal, the current surface (10) is at least partially scanned by means of the at least one optical sensor (20) in such a way that a current two-dimensional height profile (11) of the surface (10) is determined, wherein in the event of a detection of a deviation of the currently measured two-dimensional height profile (11) from the reference profile such that a limit value is exceeded, a signal is output to prevent operation of the object (1) and/or to communicate that an object (4) is located on the surface (10).