Abstract: A transducer (23) for producing a digital output signal proportional to a change in a sensed physical parameter includes first and second pairs of series-connected resistors (24, 25 or 26, 28). The electrical resistance of at least one of these resistors is variable in response to a change in the sensed parameter. The transducer also includes sine wave generators (31, 32) for applying first and second sine waves across the first and second pairs, respectively. However, these first and second exciting voltages are phase-shifted relative to one another by a constant phase angle. The voltages between the resistors of each pair are vector-summed. The phase angle of this vector-sEed signal is compared with the phase of the reference sine wave, and a pulse-width-modulated waveform is produced.

Abstract: An actively-controlled resonant-type force generator (20) is adapted to be attached to a structure (21), and includes a mass (23) mounted for movement relative to the structure and a plurality of springs (22, 24) operatively arranged between the mass and the structure. A servoactuator (26) is arranged to controllably excite the mass-spring system. The actual force (F.sub.a) transmitted from the mass to the structure is compared with a commanded force (F.sub.c) to produce a force error signal (F.sub.e). The actuator is caused to produce a velocity as a function of the error signal. The gain of the closed force loop is selected so that the resonance of the mass-spring system has an effective damping ratio (.zeta.) greater than about 0.5, and preferably about 0.7. Thus, the mass-spring system will not be substantially resonantly excited by vibrations of the structure near its resonant frequency (.omega..sub.n).

Abstract: The present invention provides an improved current spike limiting circuit (49) for a DC brushless motor controller (21) arranged to operate in six-step mode. The controller has three electrically-controllable first switches (A.sub.U, B.sub.U, C.sub.U) arranged between a supply voltage (22) and a terminal (26, 28, 29) of a respective one of the field coils (A, B, C), and has three electrically-controllable second switches (A.sub.L, B.sub.L, C.sub.L) severally arranged between a ground (23) and the field coils. The improved circuit broadly comprises a regeneration polarity comparator (50) for sensing regenerative operation of the motor; a tachometer (58) for sensing motor speed; and an adjustable pulse generator (55) from momentarily opening a conducting one of the first switches for a predetermined time interval (t.sub.p) after a predetermined delay (t.sub.d) following a point in time (t.sub.s) when one of the second switches is closed and another of the second switches is opened.

Abstract: A rotary valve (10) is adapted to be associated with a fluid source (P) and a fluid return (R), and is adapted to control the flows of fluid (via control ports C.sub.1 and C.sub.2) with respect to the opposed chambers of a fluid-powered load. The valve has a body (11) provided with an elongated bore (12). The body has a plurality of passageways (23, 24, 25, 26) communicating spaced locations along the bore with the source, return and load control ports, respectively. A spool member (28) is rotatably mounted in the bore. The spool member has a passage adapted to cooperate with a body passageway so as to define at least one flow-metering port therebetween. The area of this flow-metering port or orifice (34) is a function of the angular displacement of the spool member relative to the body from a null position. The improvement comprises each of the upstream approach walls (32, 35) adjacent the orifice being relieved at an angle (.beta.) of at least 21.degree.

Abstract: An improved motion simulator (10) includes a base (11), a capsule (14) having an at least partially-spherical smooth outer surface (15). The capsule is capable of roll, pitch and yaw angular motions about a pivot point (16) at the center of the spherical surface, and is also capable for upward and downward heave motion of the pivot point along a vertical axis (z--z) relative to the base. Actuators (33, 34, 35) are operatively arranged to selectively move the capsule relative to the base in any of four degrees of freedom. The capsule outer surface is configured such that no possible motion of the capsule in any of the permissible four degrees of freedom will cause any portion of the capsule to move outside of a motion envelope formed by an imaginary vertical cylinder (41 ) having a diameter (d) substantially equal to that of the spherical surface.

Abstract: A fluid intensifier (10) includes an unequal-area pump piston (11) and a drive piston (14). The large-area pump piston chamber (21) communicates with the small-area pump piston chamber (29) via a communicating conduit (30) having a check valve (25) therein. The pump piston is coupled to a drive piston (14) having a lost-motion connection (18) with a two-lobed pilot valve spool (41). The pilot valve (16) controls a pilot pressure in the spool end chamber (60) of a spring-biased control valve (19). The fluid intensifier is automatically reversing as the pump piston approaches either end of its stroke, and is arranged to provide a substantially-constant intensified fluid pressure (P.sub.i) at an outlet.

Abstract: An improved torque motor includes a supporting body (3) having a U-shaped cross-section and formed of a magnetizable material, includes at least two magnet structures (7, 8) adapted to be mounted on the body, includes first polepieces (10-13) mounted on the magnet structures, and includes an armature (5) mounted for movement in working air gaps (16, 17) between the first polepieces. Permanent magnets (10, 11) are mounted on the first polepieces. A second polepiece is spaced from the armature by the presence of a non-working air gap (21). At least one control coil (20) surrounding the second pole between the magnet structures (7, 8).

Abstract: An actively-controlled resonant-type force generator (20) is adapted to be attached to a structure (21), and includes a mass (23) mounted for movement relative to the structure and a plurality of springs (22, 24) operatively arranged between the mass and the structure. A servoactuator (26) is arranged to controllably excite the mass-spring system. The actual force (F.sub.a) transmitted from the mass to the structure is compared with a commanded force (F.sub.c) to produce a force error signal (F.sub.e). The actuator is caused to produce a velocity as a function of the error signal. The gain of the closed force loop is selected so that the resonance of the mass-spring system has an effective damping ratio (.zeta.) greater than about 0.5, and preferably about 0.7. Thus, the mass-spring system will not be substantially resonantly excited by vibrations of the structure near its resonant frequency (.omega..sub.n).

Abstract: An improved fluid amplifier (39) is operatively arranged in a flow path extending between a source (28, 31) of pressurized fluid (P.sub.s) and a fluid return (38) at a return pressure (R). The amplifier has at least one fluid connection (34 or 35) to a load. The amplifier has a movable mechanical member (24) operatively arranged to control the pressure at, and flow with respect to, the load. The mechanical member has a displacement range encompassing a null position and an off-null position. The improvement broadly includes a variable-impedance orifice (42 and/or 43) arranged in series with the amplifier in the low path. The impedance of the orifice is varied such that the impedance is a maximum when the mechanical member is in the null position and is a minimum when the mechanical member is in off-null position, such that flow from the supply to the return when the mechanical member is in the null position will be less than the maximum flow between the amplifier and the load.

Abstract: A fluid coupling (30) has a male half (32) and a female half (31). Each half has a poppet (35,42) arranged to move toward and way from a seat (34,43). The male half (32) has an outer sleeve (38) which is adapted to guide initial joinder of the female half distal end (46). After the two halves have been initially joined, the male half body (39) is extended relative to the sleeve (38) so as to move both poppets (35,42) off their respective seats and to permit flow through the coupling. The coupling has protrusions (76) provided with sharpened edges which are positioned to scrape ice adhering to facing surfaces when the coupling halves are joined and separated.

Abstract: A fluid-powered actuator (42) has a body (11) which includes an end wall (16) provided with a through-opening (21). A piston rod (44) has an inner portion (44A) arranged on one side of the end wall within a pressurizable working chamber (24) of the actuator, has a penetrant portion (44B) passing through the end wall opening, and has an outer portion (44C) arranged on the other side of the end wall. The rod is configured such that the transverse cross-sectional area of the penetrant portion is greater than the transverse cross-sectional area of the outer portion so as to define an annular surface (46) which faces away from the actuator chamber. The improvement provides a seal assembly (43) for containing fluid leaking from the actuator chamber.

Abstract: An improved communication system (10) includes a plurality of transceivers (A, B, C, D, etc.) adapted to communicate with one another via a common communication path. Each transceiver has its own unique identity code. The invention provides a cable (11) for temporarily enabling the mutual exchanging of identity codes between only two of the transceivers so as to establish a dedicated pair. Each transceiver has memory (12) for receiving and storing the identity code of the other transceiver of the pair, and for purging any previously-stored identity code. Each transceiver is arranged to identify all communications transmitted by it as having originated from it, and as being addressed to the other transceiver of the pair. Each transceiver is also arranged to accept communications only if addressed to it and if identified as having originated from the other transceiver of the pair.

Abstract: An electro-mechanical-hydraulic drive mechanism (10) for moving a lead (11) relative to a support (12) includes an electric motor-driven element (14) and a hydraulic reaction element (15). The two elements are arranged mechanically in series between the lead and the support. The motor-driven element may be operated independently of the reaction element to move the lead relative to the support when the reaction element is held at a fixed displacement. The two elements may be operated cooperatively to move the load when the motor-driven element is operated at a controlled velocity to pressurize the reaction element, and the reaction element is operated by controlling its pressure.

Abstract: A device (19) for generating a rotating force vector and an oscillatory couple includes a plurality of non-concentric eccentric masses (22A, 22B, 22C, 22D, 22E, 22F) co-rotating at the same angular speed; and means (24A, 24B, 24C, 24D, 24E, 24F) for individually controlling the angular position of each of the masses; whereby, by selectively controlling the angular position of each eccentric mass, the device may generate a desired rotating force vector and a desired oscillatory couple. In use, the device performs an improved method for opposing the propagation of vibration from a dynamically unbalanced rotating rotor through a supporting structure (12).

Abstract: An improved two-stage servovalve (70) has a pilot-stage and an output-stage. A torque motor (16) produces pivotal movement of a flapper (18) in response to a supplied electrical current. The pilot-stage produces a flow which is used to selectively displace a second-stage spool (61) relative to a body bore. The servovalve has a hydromechanical pressure feedback loop closed about the load and second-stage spool. The pressure feedback loop is intertwined with an electrical spool position feedback loop closed about the spool and driver. The command to the pressure loop is a function of the error of the spool position loop. The gain of the spool position loop dominates that of the pressure loop. The valve has pressure-flow characteristics approximating those of a "flow-control" servovalve but affords access to an electrical signal substantially proportional to the load pressure differential.

Abstract: A system for transducing a signal voltage into an optical signal, transmitting the optical signal via an optical fiber to a remote location in the form of light attenuation frequency and interpreting the light frequency at the remote location to the amplitude and wave form of the signal voltage. The electro optic modulator includes an elongated piezoelectric member which changes length when an electric field is imposed across it. A mirror is attached to a free end of the piezoelectric member and strains or alternately moves toward and away from a partially reflecting surface at the end of an adjacent optical fiber. Light is introduced into the fiber with a portion reflected back by the movable mirror and part by the end of the fiber. A detector at the second end of the optical fiber receives the reflected light.

Abstract: An adjustable converging-diverging nozzle (10) includes a body (11) having a flow passageway (14) therethrough. The passageway is configured to define an entrance section (18), a narrowed throat section (19), and an exit section (20). Two opposing vane members (12,13) are pivotally mounted on the body. Each vane member has a first surface (33,33') facing into the passageway to form a movable wall portion of the throat section. Each first surface is eccentric to the pivotal axis (38,38') of the associated vane member. A pair of actuators (42,43) are mounted on the body for selectively varying the angular positions of the associated vane members. The vane members may be moved to a closed position to reduce the orifice area of the throat section to zero, or may be moved to other angular positions to vary the magnitude and/or direction of the thrust vector of hot gas discharged through the nozzle. The invention also provides an improved method of operating the nozzle by selectively moving the vane member(s).

Abstract: A vibration isolator is operatively associated with a suspension having a spring (21) and a fluid damper (22) arranged in parallel with one another between two masses (23, 24) which are arranged to move relatively toward and away from one another. A restricted orifice (33) communicates the opposed damper chambers (30, 31). The vibration isolator includes a fluid pump (46) and an actuator (48) for operating the pump. The pump has a first chamber (51) communicating with the damper first chamber (30), and has a second chamber (52) communicating with the damper second chamber (31). The pump is selectively operated so as to create a pressure differential across the orifice to oppose and substantially cancel the dynamic force transmitted through the spring and damper and attributable to high-frequency relative vibration between the masses, while permitting the damper to damp low-frequency relative velocity between the masses.

Abstract: An electro-optic power cell for transducing incoming light energy from an optical fiber into electrical energy through a photo diode. An optical fiber extends into a first housing through a wall thereof. A lens in the housing abuts and is sealed to the end of the optical fiber to expand the light beam from the fiber and direct it to a photo diode in engagement with the output end of the lens. A second housing which contains an electrical socket is fastened to the first housing. Leads from the photo diode are connected to the electrical socket so that the electrical signal from the photo diode can be connected to an external electric receptacle. The optical path is hermetically sealed to prevent entry of contaminants. Several embodiments of the photo diode are described in order to perform different functions. One embodiment uses a segmented photo diode having the segments connected in series to increase diode output voltage.

Abstract: An electro-mechanical actuator has a ferrous alloy armature movably mounted within a body chamber. Two axially-spaced permanent magnets are arranged radially inwardly of the chamber and partially define the chamber at the ends thereof. A coil surrounds the chamber. The body is formed of a magnetically-permeable material. Because of the high reluctance of the magnets, each magnet forms a short magnetic loop which passes through the adjacent air gap, and forms a long magnetic loop which encircles the coil and passes through the distant air gap. The armature has a bistable toggle-like movement, and may be latched proximate either end wall. If springs are added between the armature and the body, the improved actuator may be used as a proportional position of force transducer within an operating range of armature movement.