A LVDT is a displacement sensor, which is commonly used in mechatronic systems. Consider a digital control loop that uses an LVDT measurement for position control of a machine. Typically, the LVDT is energized by a dc power supply. An oscillator provides an excitation signal in the kilohertz range to the primary windings of the LVDT. The secondary winding segments are connected in series opposition. An ac amplifier, demodulator, low-pass filter, amplifier, and ADC are used in the monitoring path. Figure P4.19 shows the various hardware components in the control loop. Indicate the functions of these components.
Figure P4.19
At the null position of the LVDT stroke, there was a residual voltage. A compensating resistor was used to eliminate this voltage. Indicate the connections for this compensating resistor.