Abstract:
PURPOSE: A method and apparatus for measuring contact force is provided to achieve improved accuracy and reduce costs by allowing contact force measurement to be performed without changing design of current collector. CONSTITUTION: A method for measuring contact force between current collector and trolley wire of motor car, comprises a first step of attaching four strain gauges at both ends of a current collector, such that Wheatstone bridge circuit is formed by using strain gauges, obtaining rate of change of bending strain of strain gauges, and obtaining shearing force affecting the cross section of the current collector by applying the obtained rate of change to the formula expressing the relation between the shearing force and bending moment; a second step of installing an accelerometer at the center of bottom surface of the current collector and at the position symmetrical to the center, obtaining a force equilibrium formula for the moment where the current collector is excited at the stopped state, obtaining equivalent mass for fan head through the transfer function of shearing force and transfer function of acceleration with respect to the excitation force, and obtaining inertial force by multiplying the equivalent mass with the signal of the accelerometer obtained during the measurement of contact force; and a third step of obtaining dynamic contact force by applying the shearing force obtained in the first step, equivalent mass obtained in the second step, acceleration measured during the measurement of contact force and aerodynamic force obtained from a wind tunnel test, to the equilibrium formula for forces acting to the current collector during travel of the motor.