Systems and methods for piston rod monitoring

A linear drive system comprising:

• a housing defining a bore;
• a piston rod positioned at least partially within the bore and translatable within the bore, said piston rod formed of a material an electromagnetic permeability that is higher than an electromagnetic permeability of air;
• and
• a sensor system for monitoring a condition associated with said piston rod, said sensor system including:
• an interrogator system including a first coil winding coupled to said housing and radially spaced from said piston rod such that a gap is defined between said first coil winding and said piston rod;
• a second coil winding coupled to said piston rod, wherein said second coil winding is inductively coupled to said first coil winding and configured to communicate with said first coil winding through a range of linear movement of said piston rod relative to said housing;
• and
• a sensor coupled to said second coil winding and said piston rod, said sensor configured to measure a characteristic associated with said piston rod and generate a current in said second coil winding to transmit, by the inductive coupling with said first coil winding and the electromagnetic permeability of said piston rod, an electrical output signal associated with the characteristic to said interrogator system.

A method for monitoring a condition of a piston rod positioned within a housing, said method comprising:

• transmitting a first electrical input signal to a first coil winding, the first coil winding coupled to the housing and radially spaced from the piston rod, a gap defined between the first coil winding and the piston rod, the piston rod is made of a material having an electromagnetic permeability that is higher than an electromagnetic permeability of atmospheric air;
• generating, from the first electrical input signal in the first coil winding, a second electrical input signal in a second coil winding coupled to the piston rod, the second coil winding inductively coupled to the first coil winding through the piston rod, the first coil winding to transmit the second electrical input signal to the second coil winding via the inductive coupling and the electromagnetic permeability of the piston rod;
• transmitting the second electrical input signal from the second coil winding to a sensor coupled to the piston rod, the sensor configured to measure a characteristic associated with the piston rod;
• and
• generating, at the sensor, an electrical output signal based on the measured characteristic and the second electrical input signal for transmission to the first coil winding via and the electromagnetic permeability of the piston rod.