| 摘要 |
<p>Apparatus for determining the position of a movable member (22) in an electrohydraulic servo system (10) which includes a linear actuator (20) having a cylinder (18) and a piston (22) variably positioned therewithin, a servo valve (12) responsive to valve control signals for coupling the actuator (20) to a source (14, 16) of hydraulic fluid, and control electronics (26) responsive to piston position for generating the valve control signals. A coaxial transmission line (40) is formed within the linear actuator (20) to include a center conductor (38) coaxial with the actuator (20) and an outer conductor (34). A bead (42) of ferrite or other suitable magnetically permeable material is coupled (44) to the piston (22) and surrounds the center conductor (38) of the transmission line (40) for altering impedance characteristics of the transmission line (40) as a function of position of the piston (22) within the clinder (18). Position sensing electronics (46, 50) include an oscillator (46) coupled to the transmission line (40) for launching electromagnetic radiation, and a phase detector (50) responsive to radiation reflected from the transmission line (40) for determining position of the piston (22) within the cylinder (18).</p> |
