| 摘要 |
<p>An electrohydraulic servo system which includes an actuator with a cylinder (18) and piston (22), a servo valve (12) and control electronics (26) responsive to piston position for generating the valve control signals. A variable frequency rf generator (34) is coupled through associated directional couplers (40, 42) to a pair of antennas (36, 38) which are positioned within the actuator cylinder (18) and physically spaced from each other in the direction of piston motion by an odd multiple of quarter-wavelengths at a nominal generator output frequency. A phase detector (44) receives the reflected signal outputs from the directions couplers (40, 42), and provides an output through an integrator (46) to the frequency control input (33) of the genrator (34) to automatically compensate frequency of the rf energy radiated into the cylinder (18) and thereby maintain electrical quarter-wavelength spacing between the antennas (36, 38) against variations in dielectric properties of the hydraulic fluid to changes in fluid temperature, etc. A second phase detector is coupled to the generator (34) and one antenna (36) to generate a piston position signal for the control electronics (26).</p> |
