Proximity detection system and method and collision avoidance system and method using proximity detection
The invention relates to a complex proximity safety and warning system. The invention provides a safety system comprising a generator that generates a magnetic field that establishes a boundary, where the generator is capable of receiving radio frequency signals. Also provided is a radio frequency device that sends radio frequency signals, the radio frequency device being capable of sensing the magnetic field and generating a radio frequency response.
1. A method of proximity detection, comprising:
generating a first magnetic field and second magnetic field;
determining a strength of the first and the second magnetic fields, respectively;
generating an alarm if the strength of the first magnetic field is above a first predetermined threshold and the strength of the second magnetic field is not above a second predetermined threshold.
2. The method of claim 1 , further comprising not generating an alarm if the strength of the first magnetic field is above the first predetermined threshold and the strength of the second magnetic field is above the second predetermined threshold.
3. The method of claim 1 , wherein the alarm is an audible alarm.
4. The method of claim 1 , wherein the alarm is a wireless response signal.
5. The method of claim 1 , further comprising generating a response signal indicative of the strength of the first and/or second magnetic fields.
6. The method of claim 5 , wherein a length of the response signal varies with the strength of the detected first and/or second magnetic fields.
7. The method of claim 5 , wherein the response during a first number of time portions indicates an alarm device is in a warning zone.
8. The method of claim 6 , wherein the response during a second number of time portions indicates an alarm device is in a danger zone.
9. The method of claim 1 , wherein the first and/or second magnetic fields are generated by a magnetic field generator positioned at a vehicle.
10. The method of claim 9 , wherein the strengths of the first and second magnetic fields are determined by an alarm device on a second vehicle.
11. The method of claim 1 , wherein the strengths of the first and second magnetic fields are determined by an alarm device and the method further comprises listening for a response signal from the alarm device during a first and second predetermined time periods, respectively following the generating of each first and second magnetic fields.
12. The method of claim 11 , wherein the alarm device is positioned on a worker.
13. The method of claim 11 , wherein the response signal is a radio frequency response signal.
14. The method of claim 11 , further comprising executing an alarm condition if the response signal is received during the first predetermined time period and a response signal is not received during the second predetermined time period.
15. The method of claim 14 , further comprising not executing an alarm condition if a response signal is received during the first and second predetermined time periods.
16. The method of claim 14 , wherein the alarm condition comprises an audible and/or visual alert.
17. The method of claim 14 , wherein the alarm condition comprises generating signal to slow a vehicle.
18. The method of claim 1 , wherein the second magnetic field defines a safe zone.
19. The method of claim 1 , wherein the first and second magnetic fields are generated at a low frequency of approximately 73 kHz.
20. The method of claim 1 , wherein the first and second magnetic fields are generated sequentially.