DE102013106704A1 - Device for non-contact detection and / or distance determination of at least one object relative to a measuring body and method therefor - Google Patents

Abstract

Devices and methods for contactless detection and / or distance determination of at least one object relative to a measuring body using an oscillating circuit for generating electrical oscillations, the capacitance of the oscillating circuit consisting of an active capacitor electrode that is connected to the device and a passive capacitor electrode that represents the object to be measured. The object influences the electric field which is emitted by the active capacitor electrode and thereby changes the capacitance of the capacitor and thus the frequency of the resonant circuit of the device. The oscillating circuit is controlled, calibrated and evaluated by a controller integrated in the device.

Description

Devices for non-contact detection and / or distance determination of at least one object relative to a measuring body are used as safety devices in machines and systems to prevent objects, such as parts of another machine, mounting parts but also people and animals in the work area to be secured Machine or plant advised and thus pose a security risk. Objects can consist of organic or inorganic materials and include humans and animals.

For this purpose, it is customary in the prior art to equip the area around the measuring body with different sensors, such as light barriers, laser measuring devices and motion detectors, in order to detect that at least one object gets into the vicinity of a said measuring body. If this is the case, signals are output, for example optical, acoustic or else electrical, which on the one hand warn of the penetrating object and also possibly control functions of the measuring body.

For this purpose, it is necessary to equip the area to be measured around the measuring body with a large number of the above-mentioned sensors in order to ensure the highest possible degree of safety in the measuring area around the measuring body.

The disadvantage of such protection around the measuring body is the number of required sensors and the exact covering of all paths to the measuring body during movement of the measuring body. If the measuring body moves, light beam laser beams and similar sensors may possibly be obscured by the measuring body itself, so that areas around the measuring body are formed which are not detected by the sensors at every moment.

Such sensors are eg from the DE10250395A1 known. These proximity sensors in combination with optical or other sensors must be arranged in a variety around the measuring body around.

To reduce the number of sensors are detections, such as from DE2005015210U1 known. These sensors work with transmitters and receivers. Thus, at least 2 elements per sensor must be used. However, since only the area between transmitter and receiver can be detected here, several sensors are also required to detect the complete area around a measuring body.

The object of the present invention is therefore to provide a device for non-contact detection and / or distance determination of at least one object relative to a measuring body, with little effort, few sensors and a high level of security that at all times all areas around the measuring body are measured or can be monitored.

This is done with the device according to claim 1 and the method for contactless detection and / or distance determination of at least one object relative to a measuring body according to claim 15.

The device consists of an electrical resonant circuit for generating electrical vibrations. This resonant circuit is based on an electrical resonant circuit, which consists of at least one coil and at least one capacitor. Optionally, the resonant circuit consists of at least one resistor and at least one capacitor, wherein both resonant circuit types can additionally be supplemented by resistors.

To supply the resonant circuit with electrical energy, an electrical power supply is provided, as well as a controller for evaluating the oscillation frequency. Likewise, the control can be used for setting the resonant circuit, as well as for calibration.

The resonant circuit itself is designed so that the capacitive part of the sensor consists of a capacitor which has only one capacitor plate or capacitor electrode. This capacitor electrode is charged by the electrical power supply and thus forms an active capacitor electrode.

This active capacitor electrode is at least partially led out of the device, for example in the form of an antenna and in that the active electrode is supplied with electrical energy, the active capacitor electrode is electrically charged, so that electrostatic field lines emanate from the active electrode.

To generate the capacitance required by the resonant circuit, the object forms a passive second capacitor electrode. Passive because the object is not connected to the electrical power supply and therefore acts passively.

Now, if the object, which acts as a passive electrode of the capacitor of the resonant circuit, in the field line region of the active capacitor electrode, the field lines are changed or deflected and / or reflected, so that a measurable change in the capacitance of the capacitor occurs. The two electrodes, ie active capacitor electrode and passive capacitor electrode, form here the capacitor plates, and the air in between forms the dielectric. However, the device is not set to air as a dielectric. Other dielectrics are conceivable, such as fluids and / or the combination of multiple dielectrics. To ensure the functioning of the capacitor, it is only necessary that the material used as a dielectric forms a sufficient insulating effect between the capacitor electrodes.

Now, if the object acting as a passive capacitor electrode gets into the field line region of the active electrode and thus changes the capacitance of the capacitor, the oscillation behavior of the resonant circuit changes accordingly. The control provided in the device now detects the change in the oscillation frequency and evaluates these changes accordingly for further processing.

The peculiarity of this device for non-contact detection and / or distance determination of at least one object relative to a measuring body is that the at least partially led out active capacitor electrode can be connected to any electrically conductive material, for example, to metal parts of the measuring body to be measured. The measuring body can therefore be considered at least partially or entirely as an active capacitor electrode. This makes it possible to take into account any area around the measuring body, even when moving the measuring body, in the measurement of the distance of an object from the measuring body, since the field lines emanating from the active capacitor electrode are emitted at each point of the electrode. Now, if the measuring body itself serves as an electrode, an electric field is built up at each point of the measuring body and thus emitted at each point electric field lines.

By this device it is possible to detect objects in an area around the measuring body around, to measure the distance and, depending on the design of the controller, also to detect movements within the measuring range around the measuring body. Thus, not only is it possible to measure distances with this device, but also to detect movements.

The resulting potential applications include safety equipment for machinery and equipment. It is often the case in the prior art that two-hand safety circuits are used so that no parts of the body of the operator get into the machine or system. This can be replaced by the device according to the invention.

Furthermore, the device can be used as intervention protection on machines or systems. In this case, the device then replaces, as already described at the beginning, light barriers and other measuring methods in order to protect an area around a machine and / or passive protective devices, such as, for example, fences and covers.

The device can also be used for gesture controls to detect fixed gestures in the field line region of the active capacitor electrode and thus to trigger controls on the plant or the machine.

Likewise, the device can be used as access protection and burglar alarm to easily protect the area around the measuring body, in this case vehicles, furniture and other items. In the field of vehicles, the present invention can also be used to detect the area around the vehicle and possibly perform emergency braking or to control evasive maneuvers.

Finally, the present invention can still be used to control automatic door systems and thus replace the photoelectric barriers or motion detectors of conventional motion controlled doors.

Finally, it is still possible to carry out non-contact functions with the present invention, such as light dimming, light switching but also non-contact gestural detections on flat screens and / or projection screens.

If the measuring body is designed so that it can be charged electrostatically, not even the active capacitor electrode must be electrically conductively connected to the measuring body for the function of the device according to the invention. It is only sufficient that the active capacitor electrode touches the measuring body. Due to the electrostatic charge, this charge is also transferred to the measuring body, so that it is then also electrostatically charged and emits field lines. This is sufficient for the function as an active capacitor electrode. This is particularly advantageous when machine parts grip or touch other parts during their movement, so that then the gripped or touched material is also added to the active capacitor electrode and the measuring body and the measuring range is increased to the body.

The frequency of the resonant circuit itself is predetermined by the components used in the device. However, it is also possible by the provided in the device control and the use of electronically adjustable components to specify the oscillation frequency of the resonant circuit. By this possibility, the controller can act on the resonant circuit and the resulting oscillation frequency. On the one hand, this is necessary when certain objects are to be detected. Different types of objects are differently suited to affect electrostatic fields and thus to change the oscillation frequency of the resonant circuit. In order to set the device to the corresponding objects, so the control can act on the frequency of the resonant circuit to allow the highest possible change in the oscillation frequency upon entry of the object in the effective range of the device.

Furthermore, a calibration by the controller is necessary to counteract environmental changes, such as humidity changes, temperature changes, etc. The frequency of the resonant circuit would also change with such an environmental change, and could be erroneously interpreted as an action of an object. Therefore, in a particular embodiment of the device, a measurement of the environmental values is provided, such as temperature, humidity, etc. On the basis of this measurement, a target range is determined by the controller, which is used as a basis for the subsequent detections. For this measurement, additional sensors are provided in the device to measure the above ambient values. These additional sensors are then electrically connected to the controller so that they can evaluate the readings of the additional sensors. However, this measurement of the environment can also be derived from the oscillation frequency alone, namely, when there are slight changes in the oscillation frequency and / or long-term, continuous changes in the oscillation frequency.

In a particular embodiment, the device has at least one output at which the frequency of the resonant circuit can be tapped. This makes it possible to read the frequency of the resonant circuit by externally connected devices and to interpret accordingly.

In a further particular embodiment, the controller used in the apparatus can evaluate the measured frequency of the resonant circuit so that the frequency of the resonant circuit is converted into a measurable electronic variable. This can be an electrical voltage which is provided in proportion to the frequency as well as another electrical oscillation whose frequency is calculated proportionally to the resonant circuit frequency or also a current or resistance value calculated by the controller, which is calculated proportionally to the measured resonant circuit frequency. This measurable electrical quantity provided by the controller can be output at the output of the device instead of the resonant circuit frequency and / or additionally.

The output can be configured as at least one electrical contact, at which the electrical variables provided at the output can be measured. The output can also be provided as a digital output, such as a serial interface, a parallel interface or a bus connection. This facilitates the connection of other external digital devices, such as a computer, to better evaluate the values measured by the controller.

The electrical power supply can be provided separately from the output of the device or as a combined component, such as a USB port, via which the power supply, as well as the data transmission to the outside.

In a preferred embodiment, the output can also or additionally be designed as at least one communication module, such as e.g. a Bluetooth module, a WLAN module, an infrared module, a BUS module and / or an Ethernet connection.

Furthermore, in a preferred embodiment, the one or more outputs may be bidirectional so that not only the signals evaluated by the controller can be output, but also commands from the controller can be issued from a connected external device, for example, adjusting the frequency of the resonant circuit. However, adjustable threshold values in the control are also conceivable, in order then to ensure various functions at the output, depending on the achievement of the threshold values, from the controller.

Since the control provided in the device can react in a preferred embodiment to environmental influences, such as temperature changes and / or changes in humidity, the controller is designed so that a calibration of the device can be performed at regular intervals to be defined. In this case, the resonant circuit is recalibrated at defined times, so that a reliable detection of the object in the measuring body region is ensured at all times even with changes in the environmental influences.

The control here consists of at least one active intelligent electronic Component, such as a microcontroller, which, depending on the embodiment, includes the following functions to perform the above-mentioned applications. It measures the oscillation frequency of the resonant circuit, converts the measured frequencies to a measurable size and provides this data at the output, either in analog form or digitally processed. For digital processing, the controller digitizes the frequency of the resonant circuit.

The controller can continue to measure environmental influences by suitable sensors or detect and control or calibrate the resonant circuit accordingly. Finally, various threshold values can be defined in the control, so that the control, upon reaching these threshold values, transmits corresponding signals at the output and / or electrically switches them at the output. These circuits can then be used to turn acoustic or optical signals on or off or to be easily measured by externally connected devices. The circuits can also be used to perform functions directly on the measuring body.

The method for non-contact detection and / or distance determination of at least one object relative to a measuring body using the device then functions in the form that, first, the control of the device is supplied with electrical energy, as well as the resonant circuit of the device. The resonant circuit is then adjusted by the controller so that a fundamental frequency to be defined is generated. This definition may be fixed in the controller, but it may also be defined by the existing output through bidirectional communication with the controller from an externally connected device, such as a computer, in the controller.

Thereafter, the controller continuously measures the oscillation frequency of the oscillation circuit, and the oscillation frequency changes when an object enters the area of the field lines. This object then changes the capacitance of the active electrode and the passive electrode capacitor of the resonant circuit and thus changes the oscillation frequency of the resonant circuit. Likewise, in this way a change in distance to the measuring body can be measured in the case of an object that has already entered the area of action.

Depending on the embodiment, the measured oscillation frequency is then evaluated by the controller. Depending on the embodiment, this evaluation may be such that the oscillation frequency is simply output at the output of the device, either in analog and digital form prepared by the controller.

Likewise, the controller can convert the measured oscillation frequency into another electrical variable and provide it in analog or digital form at the output. The thus formed oscillation frequency of the resonant circuit can thus be made audible by a speaker connected to the device and / or made visible by an optical signal connected to the device. However, it is also easy to connect an external device, such as a computer, which picks up the signal provided by the controller and evaluates it externally.

At defined time intervals fixedly incorporated in the controller or defined by the output by means of bi-directional communication with the controller, the controller calibrates the resonant circuit so that environmental influences, e.g. changing temperatures, changing humidity or occurring magnetic fields can be compensated. For this purpose, the controller may have corresponding sensors in order to be able to measure the corresponding environmental influences.

Apart from the calibration carried out at defined time intervals, the calibration can also be triggered or triggered by at least one externally connected system, such as a computer, by the bidirectional communication with the controller.

Also possible is the combined operation of several of the devices according to the invention as a system. By addressing the controls, a single controller can then make the creation and / or calibration of the resonant circuits. The digitally processed data of the controllers can thus be assigned to the respective devices.

Further features of the present invention will become apparent from the embodiments illustrated in the figures. Show it:

1 as a block diagram of a device according to the invention with a serial RS 232 interface as an output,

2 Block diagram of a device according to the invention with serial RS 232 interface and additional electrical contacts in the output.

The embodiment of 1 shows an LC element as the resonant circuit of the device. A microcontroller is used to control the device. Both are supplied by the intended power supply with electrical energy.

The controller controls the behavior and thus the oscillation frequency of the resonant circuit through the use of electronically adjustable components. In this embodiment, additional digitization between the resonant circuit and the controller is designed. However, this can also be done by the microcontroller itself.

The controller not only adjusts the frequency of the resonant circuit but also acts as a calibration of the resonant circuit. For this purpose, the frequency of the resonant circuit is measured at regular intervals and adjusted if necessary for changes. Of course, this only happens if no object has been detected. If the change of the oscillation frequency will cause an object, no calibration will take place.

For output in this embodiment, a serial interface, namely an RS 232 interface proceed in the device. This allows an external device, such as a computer, to be connected to the device which is used to read the values measured by the controller and to provide commands to the controller, such as the calibration time intervals, a calibration command itself and any thresholds, if any , which then causes the controller to send commands to the connected external device via the output. This communication with the external device is bidirectional so that values can be provided from the controller to the output at the same time, as well as commands can be sent to the controller from the external connected device. It is also conceivable, however, an output that outputs only values and an extra executed input, the command input for the controller.

2 consists in principle of a similar application example. Here, however, additional electrical contacts are provided, which make the output 1 expand. These electrical contacts, in 2 referred to as I / O ports, are used to connect external devices that can be switched by the control provided in the device. For example, upon reaching various defined thresholds, the controller may switch various contacts in the I / O ports to drive externally connected devices, such as audible signals, electrical signals, or optical signals.

These I / O ports can also be in digital form, so that connected computers can be controlled. You can also output simple electronic signals, such as voltage values, current values, or resistance values, depending on the connected external device.

The device according to the invention and the method for this purpose is not limited to the above-mentioned features. Rather, further embodiments are conceivable. For example, two controls could be provided in the device, one for evaluating the measured resonant circuit frequencies and one for setting and calibrating the resonant circuit. The output may be other than the above-mentioned interfaces, e.g. additional communication interfaces, BUS interfaces or electrical contacts. Likewise, it is ultimately possible to build the resonant circuit of two capacitors, wherein a capacitor, as described above, is designed with active and passive anode and the other a standardized electronic component in the device. The two capacitors could then complement each other to a common capacity.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10250395 A1 [0005]
• DE 2005015210 U1 [0006]

Claims (20)

 Device for non-contact detection and / or distance determination of at least one object relative to a measuring body, with an electrical power supply, with an electrical resonant circuit for generating electrical vibrations, with a control for evaluating the oscillation frequency of the electrical oscillations, as well as for calibration by definition of a nominal range of the oscillation frequency, wherein the measuring body is designed electrostatically chargeable and is electrostatically charged in the presence of electrical energy and thus emits field lines, the measuring body forms an active capacitor electrode of the capacitive part of the resonant circuit, that the object forms a passive capacitor electrode, and thus the capacitance of the capacitor and, consequently, the oscillation frequency of the electrical oscillations undergoes a measurable change upon introduction of the object into the field line region of the measuring body.  Apparatus according to claim 1, wherein the resonant circuit consists of at least one coil and / or resistor and at least one capacitor, wherein the electrodes of at least one capacitor consist of measuring body and object.  Apparatus according to claim 1 or 2, wherein the measuring body can be extended by touching other electrostatically chargeable body.  Device according to one of claims 1 to 3, wherein the frequency of the resonant circuit can be influenced by the controller.  Device according to one of claims 1 to 4, wherein the device has at least one output to which the frequency of the resonant circuit can be tapped.  Device according to one of claims 1 to 5, wherein the controller converts the frequency of the resonant circuit into a measurable electrical quantity.  Apparatus according to claim 6, wherein the measurable electrical quantity represents an electrical oscillation and / or an electrical voltage and / or an electrical resistance and / or an electric current value.  Device according to one of claims 5 to 7, wherein the output also or instead of the frequency of the resonant circuit, the measurable electrical variable can be tapped.  Apparatus according to any one of claims 5 to 8, wherein the output is a digital output, e.g. a serial interface is formed and the tappable values are digitized by the controller.  Device according to one of claims 1 to 6, wherein the device has a connection for feeding electrical energy. Apparatus according to claim 10, wherein the output and connection for supplying electrical energy are a component, e.g. a USB port. Device according to one of claims 1 to 10, wherein at least one communication module is used for communication with the controller, e.g. Bluetooth, WLAN, infrared and / or Ethernet. Apparatus according to claim 12, wherein the communication module also serves as an output and / or communication module or output is also used for bidirectional communication with the controller. Apparatus as claimed in any of claims 6 to 13, wherein the controller has adjustable thresholds to affect the measurable electrical quantity. Method for contactless detection and / or distance determination of at least one object relative to a measuring body using the device of one of claims 1 to 14, wherein first the control is supplied with electrical energy, then the resonant circuit is calibrated by the controller so that a target range of the oscillation frequency is set, the controller then continuously measures the oscillation frequency, wherein the oscillation frequency changes when an object enters the area of the field lines and / or changes its distance to the measuring body, and the measured oscillation frequency is evaluated by the controller. The method of claim 15, wherein the evaluated oscillation frequency is made audible by a speaker connected to the device.  The method of claim 15, wherein the evaluated vibration frequency is visualized by an optical signal connected to the device.  The method of claim 15, wherein the evaluated vibration frequency can be tapped by at least one output. Method according to one of claims 15 to 18, wherein the controller calibrates the resonant circuit in defined times, so that environmental influences, such as changing temperatures, changing humidity, electromagnetic fields occurring, are compensated.  The method of claim 19, wherein the calibration can also be performed by control signals by means of output or the communication module.  System having a plurality of devices according to any one of claims 1 to 14, wherein, by addressing the controls, a single controller performs the adjustment and / or calibration of the resonant circuits and / or reads and provides the data of the addressable controllers, which data then is the output individual devices can be assigned.

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