Difference between revisions of "Magnet detector configuration v1"

Revision as of 17:51, 31 July 2017

General functionality description

Device can works in configuration of two separate dual (two sensors) magnet detectors. So device has two connectors for magnet sensors cables (each cable connect two magnet sensors).

Device has two separate group of parameters (Magnet 1 and Magnet 2) for tuning dual magnet detectors and it has four groups of parameters (MS 1..4) for sensor tuning. These parameter groups allow you to configure the detection of magnets by two dual magnet detectors separately.

The system responds to a change in the magnetic field in the range of the sensors. If reaction correspond to magnet detection settings it consider as alarm. So internal state is changing to alarm state, alarm counter is incrementing, common system buzzer is switching-on ("fast beeps"), external LEDs (1, 3) indication is switching-on. After a short time when magnetic field is not changing (magnet is not moving) or it is out of the detection area, if reaction is less then magnet detection settings it consider as end of alarm. So internal state is changing to normal state, common system buzzer and corresponded external LEDs indication are switching-off.

Also each magnet detectors can use two-sensor measurements for filtering false alarms caused by "far located strong magnet" (urban transport, elevators), impulse disturbances (electrical drive of sliding doors, power converters).

At the same time, each magnet detectors can use corresponded metal detector data for correction the magnet detection. These functions are intended for detecting magnets when used on an object (for example, cash registers of hypermarkets), in the area of ​​operation of a system of trolleys with an iron structure, since iron has the properties of a magnet.

The device can send information about the number of alarms for a period or a message about the operation based state variables to account the statistics of the alarms and for synchronization with the video surveillance systems.

Parameters description

Fig. 1: shows an example of the change in the state of the state in time, depending on the indicator value (dV) and the influence of the tuning parameters (th, th in delay, th out delay)

Parameters groups MS x for magnet sensor tuning.

• dV - the response of the system over the magnetic field
• th - sensitivity detection setting. The parameter values ​​are selected based on the noise level (0.25 ... 10.0)
• Babs - current level of field strength in mGs measured by the sensor
• bsize - the size of the history buffer for analysis (100 - corresponds to 1 second maximum value 250, minimum 10)
• window - analysis window (50 - corresponds to 0.5 sec). The bsize / window ratio affects the speed sensitivity of the magnet
• in delay & out delay - time setting for detection when dV is exceeded above th and at detection loss at dV is less than th
• state - the state of detection of the magnet
• alarm counter - the lifetime magnet sensor events counter.

Parameters groups Magnet x for magnet detector tuning.

• algo - the detection algo.

 *0. Simple magnet detector. Detection is depended only on sensors 
 sensitivity settings (MS 1, 2 for Magnet 1  MS 3, 4 for Magnet 2). 
 When one of two sensors detects magnet it's consider as magnet detector alarm. dV is not affected in this mode
 1, 2 Dual magnet detector in gain sense mode 1 and 2. The main detection variable dV is calculated as a sum of each sensors responses without/with sign of values
 considering.
 10, 11 Dual magnet detector in magnet filter mode 1 and 2. The main detection variable dV is calculated as a delta sensors responses without/with sensors space 
 orientation considering.
 considering.
 20, 21 Dual magnet detector in metal filter mode 1 and 2. The main detection variable dV is calculated as a sensors responses with with metal detector data 
compensations.

 When one of two sensors detects magnet it's consider as magnet detector alarm.

• dV - the overall response of the system to the magnetic field with compensation
• th - sensitivity detection setting. The parameter values ​​are selected based on the noise level (0.25 ... 10.0)
• win magnet - the size of the history buffer (5 - corresponds to 0.05 sec) for the analysis of changes in the magnetic field
• win metal - the size of the history buffer (10 - corresponds to 0.1 sec) for analysis of changes during the movement of metal
• in delay & out delay - time setting for detection when dV is exceeded above th and at detection loss at dV is less than th
• state - the state of detection of the magnet
• alarm counter - the lifetime magnet sensor events counter.

See figure 1 for details.

Setting parameters for detecting magnets

1. The magnets detection settings are made separately for magnetic sensors A and B, see corresponding magnet-A, magnet-B parameter groups. The difference between the use of sensors A and B is that a separate LED (green) and sound indication is provided only for sensor B.

In order to indicate the alarms through sensor A, you must additionally configure the magnet with trolley to detect magnets without metal compensation. In this case, the light (red) and sound signaling corresponding to the magnet with trolley functionality will be used.

Sending information on the number of shifts of magnetic detectors for a period or messages about a tripping can be performed on the basis of counter and state variables independently.

2. To assess the level of the magnet's influence, use the variable dV, which should be chosen for monitoring. The system should tuned to the best sensitivity when detecting moving magnets using the parameters th, buffer size, buffer window, th in delay / th out delay, taking into account the noise level.

The magnet detector is evaluated using the state and counter variables, as well as based on the external LED indication (green for magnet-B).

The range of detection depends on the level of magnetic induction of the magnet, the direction of its magnetic field and the speed of motion. For tuning, you can use a standard magnetic puller with an induction of 6-10,000 Gauss.

After the settings, save the settings.

3. False triggering in some cases can be caused by impulse and constant interference at the installation site, for example, when the sliding doors (especially with the DC collector drive) are close (<2 m), when power consumers switch on/off the power line (depends on Parameters of the mains), with close proximity (<0.5 m) of mains power lines, with close location (<25 m) of transport routes (metro, tram, parking). The detuning from false alarms can be performed by a load of sensitivity (increase in th), as well as an increase in the delay in triggering th in delay.