Technique of measuring the amount of fuel in a tank

Definition of fuel volume

To receive the report of volume of refuellings and possible thefts of fuel, it is necessary the data from the fuel level sensor from standard units of height of a column of a liquid or value in mm, totransfer in values of volume in liters.

The fuel level sensor (capacitor) during the process of installation has to be cut to a height of a tank and has some initial offset of target value. Because of features of the form for different tanks the height of a column of a liquid will correspond differently to volume. For exact calculation of volume of fuel in process of calibration of a tank the table of transfer of level of standard units in liters is calculated.

Level of fluctuations during movement

During movement of the object fuel also is in constant movement and fluctuations of its level are measured in a tank by the sensor. Simple mathematical smoothing of fluctuations of fuel brings inadmissible distortions in the data. For example, ruoff 20l of fuel directly ahead of refuelling in the majority of systems will be "smoothed" and will pass not noticed.

On the picture the typical schedule of fuel level is represented during performance of operations of loading of rubble by loader CASE. As you can see on the schedule, level of fluctuations is 50-80l, speed of movement according to the GPS-receiver in some areas doesn't exceed 3km/h. The loader moves with less speed of the pedestrian, often under a bias, with a list of the case to 45 °.

Unfortunately, the information about condition of an ignition lock cannot be used as a signal of technics work and its movement such as draining of fuel at the engaged ignition that is quite possible and should be fixed.

The given problem is the basic source of errors in all systems with measurement of the, irrespective of type of sensor, and can't be ignored by the manufacturer.

The connected tanks

When there are some tanks on a vehicle, the measuring system should allow to summarize values and inform the level in each reservoir separately. In case of the connected tanks calibration of the system becomes more complicated and it is necessary to consider that.

Measurement of fuel on base of module "Drozd", IS12

The equipment "Drozd" in a complex with the program "Signalman" allows to automate calibration process of a tank, having excluded a fuel gulf by measured capacities and occurrence of additional sources of errors. Measurement of volume of the filled in fuel is carried out by the checked fuel consumption sensor with a margin error not more then 0,2 %, in addition compensated on temperature and firmness of used fuel.

Module IS12 independently carries out recalculation of fuel level in volume in liters. If there are several tanks on a vehicle, each adapter IS12 is calibrated separately according to unitary filling with fuel of all  the system. Module "Drozd" remembers quantity of tanks and fixes as total value of volume of fuel in liters, and separately on each tank. Besides, according to the main principle of experiment,is fixed the value of primary parameter in units of the sensor for the subsequent analysis of reliability of the data.

With algorithms of a numeral filtration in the equipment "Drozd" is provided elimination of casual bursts and hardware errors of sensor "Strela-CH", compression of the repeating data and more detailed record of events of reflueling/draining, and also control of events of sabotage.

For elimination of false responses to oscillations of fuel during driving, the equipment "Drozd" adds to information of IS12 parameters of driving of object using 3D-sensor of moving and receiver GPS (software "Drozd" V4.5 and is higher). As we can see on the schedule, the object is moving actively at zero speed agrees to GPS receiver and to use values of fuel level for determination of events of refueling during these moments is undesirable.

The exact calibration and difficult filtering system of events in a complex allows to achieve reduce of errors of calculation of fuel rest to units of litres in a tanks in volume 300-400l. During systems operation on cars and career technics the system gives the data of events about fuel with probability of 99 %.

The main goal of the fuel monitoring system consists in that during an automatic mode to find out suspicious events and to pay managers attention to these events. Anyway, systems of measurement of fuel level remains indicators of volume of rest of fuel in a tank, though also exact enough.

The given development were led during the last one and a half years that gives an opportunity to estimate operation if  measuring system is correct, instead of entering "ceiling" coefficients to roughly measured values, writing off then all errors on drivers.