Approach warning system for detecting when a person approaches an object, particularly a machine
An apparatus relates to an approach warning system for detecting when a person approaches an object which has a metal outer structure at least in regions. The system is formed with at least a first near-field device which is associated with the object and a second near-field device which is associated with the person, wherein the first and the second near-field device form a transmission link for an electric near field, and with a warning device which outputs an approach warning signal when a person with the second near-field device enters a detection region in which a transmission of the near field via the transmission link takes place, wherein the first near-field device is connected, for the purpose of coupling to the near field, firstly to a stray field electrode and secondly to the metal outer structure of the object, so that the outer structure forms a counter-electrode for the stray field electrode, and wherein the near-field devices and the electrodes thereof are configured such that the detection region at least approximately encloses the entire outer structure of the object.
1. Approach warning system for detecting when a person approaches an object, in particular a machine, which has a metal outer structure at least in regions, comprising
at least a first near-field device which is associated with the object and a second near-field device which is associated with the person, wherein the first and the second near-field device form a transmission link for an electric near field, and
a warning device which outputs an approach warning signal if the person with the second near-field device enters a detection region in which a transmission of the near field via the transmission link takes place,
wherein the first near-field device, for the purpose of coupling to the near field, is connected firstly to at least one stray field electrode and secondly to the metal outer structure of the object, so that the outer structure forms a counter-electrode for the stray field electrode, and
wherein the near-field devices and the electrodes thereof are configured so that the detection region at least approximately encloses the entire metal outer structure of the object.
2. Approach warning system according to claim 1 ,
wherein
the first near-field device associated with the object is a near field generator for generating the near field and
the second near-field device associated with the person is a near field detector for receiving the near field.
3. Approach warning system according to claim 1 ,
wherein
the object is a vehicle, in particular an agricultural vehicle, and the metal outer structure is a bodywork of the vehicle.
4. Approach warning system according to claim 2 ,
wherein
the stray field electrode is arranged above a roof of the bodywork.
5. Approach warning system according to claim 2 ,
wherein
the stray field electrode is arranged in a bumper of the bodywork.
6. Approach warning system according to one claim 1 ,
wherein
the stray field electrode is in the form of a spherical electrode.
7. Approach warning system according to claim 1 ,
wherein
the metal outer structure can be earthed.
8. Approach warning system according to claim 1 ,
wherein
the metal outer structure is formed in multiple parts, wherein between the individual parts an electric, for example metal, coupling is produced, in particular through a releasable electric connection, for example a plug-type connection.
9. Approach warning system according to claim 1 ,
wherein
the electric near field is an alternating field,
wherein an oscillation frequency of the alternating field preferably lies in the range from 10 kHz to 10 MHz, in particular being around 5 MHz.
10. Approach warning system according to claim 9 ,
wherein
the alternating field is a continuous (CW) alternating field.
11. Approach warning system according to claim 2 ,
wherein
the near field detector comprises means, in particular a band pass filter for differentiating the near field generated by the near field generator from other fields, and
connected after the differentiating means is a decision circuit, in particular a threshold value switch, which decides whether a person is approaching the object on the basis of a signal strength of the near field present on the near field detector.
12. Approach warning system according to claim 2 ,
wherein
the near field detector comprises a radio transmitter and the radio transmitter is adapted to change the composition of a radio signal generated by it in dependence upon a signal strength of the near field present on the near field detector.
13. Approach warning system according to claim 12 , characterised in that
the warning device is arranged on the object and comprises a radio receiver for detecting and/or evaluating the radio signal from the radio transmitter.
14. Approach warning system according to one of the claim 2 ,
wherein
a second radio transmitter is associated with the object and a second radio receiver is associated with the person, wherein the second radio receiver comprises means for activating the near field detector upon receipt of a radio signal from the second radio transmitter.
15. Approach warning system according to claim 2 ,
wherein
the near field generator comprises an electric oscillation generator for generating the alternating field,
wherein the oscillation generator preferably comprises means for keeping an oscillation frequency constant.
16. Approach warning system according to claim 15 ,
wherein
the oscillation generator is adapted to generate a sinus oscillation.
17. Approach warning system according to claim 15 ,
wherein
the oscillation generator is galvanically insulated from an onboard network of the object and comprises means for setting an oscillation amplitude level.
18. Approach warning system according to claim 1 ,
wherein
the second near-field device, for the purpose of coupling to the near field, is connected firstly to a body electrode associated with the body of the person and secondly to a second electrode at a distance from the body electrode which forms a counter-electrode for the body electrode.
19. Approach warning system according to claim 18 ,
wherein
the body electrode is in the form of a ring electrode which is provided in particular to surround an arm or a leg of the person.
20. Approach warning system according to claim 18 ,
wherein
the body electrode and the counter-electrode of the second near-field device are electrically insulated in relation to the environment.
21. Warning process, in which an approach warning system according to claim 1 is provided and by means of the warning device a warning signal is output if a person enters the detection region.
22. Approach warning system according to claim 15 ,
wherein
the oscillation generator is galvanically insulated from an onboard network of the object and comprises means for setting an oscillation frequency.
23. Approach warning system according to claim 1 ,
wherein
the stray field electrode is elongated and extends perpendicular to adjacent sections of the metal outer structure.