Fluxgate Sensors for Onboard Weighing Systems of Heavy-Duty Dump Trucks

The article reviews the results of the authors’ research on the possibility of using the magnetic field strength generated by DC traction motors as a useful signal carrying information about weight of cargo transported by a mining dump truck. The objective of the research was to find a way to determine weight of cargo carried by a mining dump truck. In contrast to the existing onboard weighing systems, it becomes possible to create a compact autonomous device that does not require integration of sensors into the body structure and electrical circuits of the truck. Problems of increasing the efficiency of measuring devices based on fluxgate converters are considered with the view of using them as onboard systems for estimating cargo weight. The sensitivity of the fluxgate sensor can be increased by increasing both the amplitude and the effective value of the voltage applied to its excitation winding. The proposed original circuit for feeding the fluxgate sensor’s excitation winding from a modulated signal generator made on logical elements allows increasing the voltage supplied to the fluxgate sensor’s excitation winding without increasing the supply voltage, and by increasing voltage surges at the fronts of rectangular modulated high-frequency pulses, as well as due to resonant phenomena. The use of such a generator excludes the influence of the fluxgate sensor’s excitation winding on the generator frequency, since the frequency of modulating signals becomes the operating frequency of the fluxgate sensor, and it remains unchanged. The increased sensitivity makes it possible to install the sensor in any convenient place in the dump truck cab, and not in the immediate vicinity of traction motors. Evaluation of cargo weight is carried out during movement of the dump truck along the control section of the road. The readings are taken from an ammeter (milliammeter), the scale of which is pre-calibrated in mass units. Measurements of mass should be carried out under the same modes of dump truck movement and with the same location of the fluxgate sensor as when calibrating the scale of the measuring device. The control section of the route on which the measurements are carried out must be the same or similar to the one on which the measuring device was calibrated. The proposed device is distinguished by ease of use, is characterised by low energy consumption, is compact, does not contain expensive elements and does not require careful maintenance.