Showing papers on "Actuator published in 1981"

Vehicle mirror assembly

Abstract: A day/night rearview mirror assembly for vehicles including a one-piece, molded, resinous mirror case having flexible, resilient portions and a substantially rigid pivot actuator which is biased by the case into either a day or night position. Movement of the actuator changes the position of the case and mirror element thereby changing the amount of light reflected. An interference fit between supports for the actuator within the case and the pivot actuator expands and pre-stresses the case to provide a predetermined biasing force which must be overcome by a pivoting force to move the actuator between its positions. A continuous lip extending around the periphery of the case allows snap-in insertion and permanent retention of a preferably prismatic mirror element. The retaining lip is sized to maintain coverage of the edge of the mirror element even during flexing of the case while the actuator is pivoted.

Controllability measures and actuator placement in oscillatory systems

Abstract: Oscillatory systems provide a good linear description of large flexible space structures. Considering the problem of controllability measures for these systems leads to a design approach for actuator placement in such systems. It is shown that the mathematical form associated with an oscillatory system lends itself to a complete modal analysis that can be written in closed form. This available modal structure and the controllability measures are combined to yield a design approach for optimal placement of actuators in oscillatory systems.

A quarter century of disk file innovation

Abstract: This paper traces the development of disk file technology from the first disk drive to the present. A number of innovative advances are reviewed in the evolution of mechanical design, materials, and processes. These advances constitute the technological base that has permitted almost four orders of magnitude of improvement in areal density; they are discussed from four in terrelated aspects: the magnetic head and its air bearing support; the head positioning actuator; the disk substrate and its magnetic coating; and the read/write signal detection and clocking electronics.

Controlled motion apparatus

Abstract: A controlled motion apparatus capable of at least three degrees of freedom, such as apparatus for vibration testing of equipment, comprises a support suspended from a reaction mass by three anti-rotation, linear motion displacement actuator devices each extending and movable along one axis of an XYZ coordinate system. Each actuator may be independently activated to cause the support to undergo simultaneously controlled motion along the three axes.

Drawer slide locking lever

Abstract: A drawer locking lever pivotally mounted between its ends to a drawer mounting strip, with a drawer rail locking element at one end of the lever and an integral deformable spring element at the other end for biasing said locking element toward a drawer rail, there being an actuator element at said other end of the lever for pivoting the lever against the bias of said spring element to release the locking element from the drawer rail.

Electronic controller for valve actuators

Abstract: An electronic controller is provided to control the energization of an electrical actuator to readjust a valve which controls the flow of a fluid in a controllable process. The controller is responsive to two signals, one of which is produced by a process sensor to represent the instantaneous magnitude of a predetermined process parameter and the second of which constitutes a set signal representative of a desired magnitude of the parameter. The signals are compared, and the sense of any resulting error signal is used to control the direction of movement of the actuator while the instantaneous magnitude of the error signal, during a succession of equal time intervals, is used to control the rate of movement of the actuator by controlling the extent of movement of the actuator during each of the time intervals. The actuator is jointly responsive to these two controls and moves in a series of incremental steps, the sizes of which decrease exponentially to match the process loop variable's exponential change with time, as the error signal reduces to zero.

Fluid-powered actuator having a cylinder with magnetic field detectors thereon and a magnetized piston rod

Abstract: For producing readings representative of the position of a fluid-powered actuator, a magnetic position-sensing system is used which is out of contact with the actuator's ram and is completely united with the actuator's cylinder. The sensing system has a periodic magnetic field pattern of the ram itself and a number of magnetic field detectors placed in an end plate of the actuator clear of the ram's outer face. The true position of the ram within one period of the magnetization pattern is measured by electrical interpolation based on output signals of the different magnetic field detectors.

Electromagnetically operating actuator

Abstract: An electromagnetically operating actuator for control elements capable of making oscillatory movements in displacement machines, more particularly for flat slide shut-off valves and lift valves, includes a spring system and a pair of electrically operating switching elements, over which the control element is movable in two discrete opposite operating positions and is retained thereat by either switching magnet, the locus of the position of equilibrium of the spring system lying between the two operating positions. The invention is characterized by the provision of a compression device in engagement with the spring system for relocating the locus of the position of equilibrium of the spring system upon actuation of the compression device.

Circuit pressure control system for hydrostatic power transmission

Abstract: A circuit pressure control system for a hydrostatic power transmission having a variable-displacement hydraulic pump driven by a prime mover, a hydraulic actuator for actuating a load and a displacement adjusting mechanism for the hydraulic pump. The hydraulic pump and actuator are connected together in closed or semi-closed circuit, and the displacement adjusting mechanism is actuated by a signal indicative of the operating lever manipulated variable and a signal indicative of the actual displacement of the hydraulic pump to control the speed of the hydraulic actuator. The circuit pressure control system is provided with a sensor for sensing the circuit pressure of the hydrostatic power transmission and generating a signal indicative of the sensed circuit pressure, a device for calculating based on the manipulated variable and circuit pressure signal a hydraulic pump displacement command that causes the displacement of the hydraulic pump to be changed at a maximum rate when the circuit pressure is below a predetermined value and causes the changing rate of the displacement to be reduced when the predetermined value is exceeded thereby, and a device for comparing the displacement command with the actual displacement of the hydraulic pump and producing a signal for decreasing the difference between them and supplying such signal to the displacement adjusting mechanism.

Self-contained closed-loop electrically operated valve

Abstract: The invention contemplates an electrically operated valve construction for control of fluid flow wherein an actuator module is adapted for detachable connection to a valve-body module which contains the valve member to be automatically positioned by a driver element of the actuator module. All electronic components for moving the driver element are self-contained in the actuator module, and these elements include a fluid-sensing transducer producing an electrical output, for closure of the control loop. The transducer has sealed exclusive exposure to fluid in the valve-body module via a special port within the confines of the interface between the modules, when the modules are assembled to each other; this port communicates directly with that part of the valve-body passage which is on the downstream side of the valve member. An electric cable for external supply of power (and, if desired, command signals) is provided to the actuator module via connector elements exposed for detachable connection at the interface between modules, so that the actuator module requires no wiring or plumbing or other mechanical coupling that is not detachable at the interface between modules.

Electric command spoiler system

Abstract: An aircraft spoiler control system wherein each of a plurality of spoilers is driven by an electrically responsive actuator. Sense signals representative of the aircraft's control wheel rotation, speedbrake lever deflection, flap position and air/ground status are processed by logic which produces a corresponding control signal for each actuator. Fault detection circuitry switches in a back-up actuator control signal if a fault occurs in the active control circuit.

Robust Flight Control: A Design Example

Abstract: A novel parameter space method is used as a tool for the design of a robust stabilization system for the shortperiod longitudinal mode of a fighter aircraft. The example is an F-4E with additional horizontal canards. Robustness is achieved, in the sense that military specifications for damping and natural frequency are satisfied, by a constant controller in spite of perturbations. The perturbations are changing flight conditions and undetected sensor failures. The resulting controller structure requires two gyros and one accelerometer. The system, including actuator dynamics and feedback dynamics, is of sixth order and, in the design, four free controller parameters have been assumed. Practical considerations are taken into account, such as bandwidth limitation below structural vibration frequencies, actuator limitations, and relaxed emergency specifications in failure situations.

Railway Vehicle Active Suspensions

Abstract: SUMMARY This paper reviews the state-of-the-art of active suspensions for use on railway vehicles. The primary focus of the paper is on ride quality control, both vertical and lateral, and on lateral stability control. The section on theoretical considerations summarizes the results of a one-degree of freedom optimization and then investigates analytically the use of active suspensions for lateral ride and stability augmentation. It is shown that separate control structures using different measurements and actuator actions are very effective in controlling both ride quality and stability. A section on a survey ofcurrent activities reviews published research on active railway suspension work around the world. Finally a concluding section indicates future trends in active suspension applications.

Electromagnetically operated adjusting device

Abstract: An actuator assembly for an electromagnetically-actuated, spring-loaded positioning system in displacement engines, such as for lifting valves in internal combustion engines. The positioning mechanism comprises a three-spring system and two electrically-operated, opposed actuating solenoids, by means of which the actuator may be moved therebetween, and held at, two discreet, mutually-opposite operating positions. The actuator assembly further comprises an anchor plate having integrally attached upper and lower stems, wherein the lower stem engages the upper flanged end of a valve stem and, upon reciprocation of the anchor plate, transfers movement to the valve stem which moves the valve from a closed to an open position, or vice-versa. The actuator assembly is symmetrically biased by upper and lower halves of the three-spring system. The upper spring system includes a first spring disposed to engage the upper stem and stressed to force the actuator assembly to the open position of the valve head. The lower spring system comprises: A second spring disposed to engage the lower stem and stressed to move the actuator assembly to the closed position of the valve head; and A third spring disposed to engage a stamp flange on the upper end of the valve stem which spring is stressed to assist the second spring in moving the actuator assembly to the closed position of the valve head. Spring constants of each spring are selected to provide a constant neutral point of the spring system over the service life of the actuator assembly.

Control system for papermaking machine headbox

Abstract: A system for the control of a paper machine headbox having sensors for the measurement of the parameters of the process and actuators of the members of the process, functionally connecting at least most of the sensors to an at least equal number of actuators via a multivariable centralized control member which makes it possible to control each actuator by the taking into account and processing of the measurement information of one or more sensors, and causing the measurement information to act on each of the sensors functionally connected to the actuators on one or more members to obtain a resultant action in which only the parameter measured by this sensor is influenced while the secondary repercussions on the outer parameters are eliminated. Another characteristic, the invention permits rapid intervention taking into account the information on the substance flow rate at the headbox, eliminating the usual disturbing influences due to the hydraulic values of the process.

Circuit for tracking and maintaining drive of actuator/mass at resonance

Abstract: A drive circuit (10) for driving an actuator/mass (A) at its natural resonance and for maintaining the instantaneous output signal of the mass at a predetermined constant value over a wide range of dynamically changing resonant frequencies, is disclosed. Current sensing circuitry (C) detects an instantanous current passing through the actuator/mass (A). A compensation circuit (D) modifies the instantaneous sensed circuit signal to compensate for dynamically changing physical parameters of the actuator mass and for phase irregularities introduced into the sensed signal when the mass oscillates near its natural resonance. Automatic gain control circuitry (E) alters the actuator drive signal to maintain amplitude of the mass oscillation at a predetermined constant value. A drive circuit (B) performs the actual drive function in response to the feedback signal received from the automatic gain control and compensation circuitry.

Anti-skid vehicle braking systems

Abstract: In an anti-skid vehicle braking system an electronic control unit is arranged to control the operation of an anti-skid valve assembly for modulating the fluid pressure applied to a brake actuator. A wheel speed sensor measures the speed of a braked wheel and produces a signal which is converted into a deceleration signal by a conditioning circuit and a differentiator and compared in a comparator with a deceleration threshold value. A pressure sensor provides a pressure signal corresponding to the current brake actuator pressure and a pressure signal conditioning circuit modifies the pressure signal to take account of a load signal produced by a load sensor which measures the loading of the braked wheel. The deceleration threshold value is produced by modulation of a constant threshold value in a threshold generator circuit and a threshold modulator circuit in response to the modified pressure signal. The threshold value is varied in response to the current pressure signal in accordance with a predetermined relationship between the threshold value and the brake actuator pressure, with a higher threshold value being provided for a higher actuator pressure. When the system is applied to the brakes of a low inertia axle, an over-ride circuit is included to provide a signal which over-rides the pressure signal for an initial period when the brake is applied as detected by a brake lamp switch.

Method and apparatus for generating electrical energy from the rotation of a wheel

Abstract: Both a method and an apparatus for generating electrical energy from the rotation of a wheel are disclosed. The apparatus is disposed within a pneumatic tire of a non-magnetic wheel and includes a non-magnetic support track circumferentially attached around the wheel, at least one coil positioned along the track, a magnet slidably engaging the track, and an actuator attached to the magnet for developing a drag upon the magnet to cause relative motion between the magnet and coil as the wheel is rotated.

Locking, redundant slat drive mechanism

Abstract: A slat system in which the slats are supported on tracks and the slats are actuated by a simple bell crank linkage oriented so that its plane of motion is parallel to the wing chord reference plane. The mechanism retracts to a collapsed over-center position and extends to an over-center position so as to lock the slat into the retract or extend positions. Each slat segment is driven by two identical mechanisms tied together by a synchronization link which provides redundancy. Either actuator can drive the surface alone, as the second actuator is driven through the synchronization lever, in case of power loss to the second actuator.

Integrated multiplane actuator system for compressor variable vanes and air bleed valve

Abstract: A linkage system for actuating the variable vanes and the air bleed valve of a gas turbine engine compressor in an intermittent sequence includes a single actuator and a linkage mechanism. The latter is formed of a first actuating linkage extending to the bleed control valve, a second actuation linkage extending to the variable guide vanes, and an intermediate crank mechanism connected to the first and second actuating linkages and also to the single actuator. The linkage system is operative to convert the linear motion from the single actuator to multiplane intermittent rotational motion of the actuating linkages extending to the variable vanes and the bleed valve of the compressor. When embodied in a military aircraft, the single actuator is preferably disposed above the compressor casing so as to make it less vulnerable to enemy ground fire.

Method and apparatus for precisely moving a motor armature

Abstract: Electromagnetic actuators are disclosed for precisely and directly incrementing an output member along a given generally linear path. Included in one actuator is a pair of assemblies, one of which is movable with respect to the other along the given path. A first of the assemblies includes means for producing a first magnetic field extending to the second actuator assembly in a manner generally transverse to the given path. The second actuator includes energizable means alongside the path and for producing a pair of opposed, approximately equal magnetic fields, spaced along the given path. Each of these opposed fields being aligned to cooperate with the transverse field to produce a force between the assemblies tending to centrally locate the assemblies with the transverse field between the pair of opposing fields.

Laminating roll actuating crank mechanism

Abstract: A pair of laminating rolls are respectively connected to a first and a second actuating arm themselves pivotally mounted to a slotted actuating link. The link is itself pivotally mounted to a single actuator. The link is arranged such that opening and closing forces are simultaneously applied to the arms to open and close the laminating rolls.

Linear head actuator

Abstract: An actuator for linearly moving magnetic heads in which an open-ended carriage assembly extends down both sides of the magnet structure in order to provide a much shorter actuator assembly than is typical is described. The loading mechanism is not mounted upon the carriage assembly, thereby allowing the actuator to have a higher resonant frequency than those actuators which carry a more complex structure on the carriage assembly. The magnet structure is in the shape of an E with the motor coil, which is mounted across the open end of the carriage assembly, moving along this center section of the magnet structure. Alignment pins located at the other end of the carriage assembly allow the magnetic head arms to be mounted and aligned quickly and with precision.

Personal defense actuator

Abstract: A directional applicator for a self-defense product includes a container having a bottom, side walls and a top; a valve mounted to the top of the container, an actuating stem, having an axial dispensing bore, for the valve, projecting outwardly from the container; an actuator with a first part having therein a spray nozzle disposed on the stem of the nozzle disposed on the stem of the valve with the nozzle in communication with the bore, and a second actuator part fixedly mounted to the container; and a key-ring mounted to the first part which is fixed to the container for axial sliding movement along the applicator between a position where it is adjacent to the actuator and a position where it is spaced from the actuator sufficiently to permit a thumb or finger to be inserted between the key-ring and actuator to operate the actuator to thereby provide a safety feature to prevent accidental actuation.

Variable stator vane operating mechanism for turbomachines

Abstract: A variable stator vane operating mechanism for a gas turbine engine includes a plurality of unison rings 21,22 and 23 each connected by a drag link 18,19 and 20 respectively to a pivoting beam 14. The unison rings are connected to each of vanes 10 in a stator vane row by first arms 24. In order to minimize side loads on the unison rings by the drag links during pivoting of the beam, the beam is connected at its free end to a second arm 30 which is pivotable about an axis 28 by means of a torque tube 26 or other suitable actuator, and the length of the second arm 30 between the axis 28 and its point of connection 44 to the beam is made as nearly as possible equal to the length of the first arms 24. By this means the fore and aft movement of the beam can be matched to the fore and aft movement of the unison rings, or at least in the case of one of them, and the drag links remain substantially in the plane of the unison rings.

Streamlined multi-axis robot wrist assembly with partially enclosed hydraulic and electrical lines to minimize the wrist envelope

Abstract: A multi-axis robot wrist assembly having three hydraulically operated rotary actuators which are mechanically connected in series such that the output of each actuator drivingly positions the body of the succeeding actuator located outboard thereof. The hydraulic connection to any wrist actuator, except the innermost actuator, includes a series-connection of (a) internal passage(s) through actuator(s) which are located inboard of the actuator in question and (b) external line(s) between the actuator in question and actuator(s) located inboard thereof. By connecting all but the innermost wrist actuator through hydraulic paths which are at least partially internal to actuators positioned inwardly thereof, the overall envelop of the wrist assembly is reduced. Also included for the purpose of minimizing the wrist envelop is an electrical cable arrangement for connecting the electrical outputs of position transducers associated with each wrist actuator to an electrical plug or other suitable connection located on the robot arm which mounts the wrist assembly. The electrical cable, includes semicircular folded sections between each pair of adjacent actuators and partially encircling the rotatable output member interconnecting them, to permit adjacent actuators to rotate with respect to each other without damaging the electrical cable spanning them, which remains neatly folded between the actuators. The mechanical interconnection between the rotary output member of one actuator and the body of the succeeding actuator is detachable, facilitating actuator replacement in the field without replacing the entire wrist assembly.

Modeling and control of flexible space structures

Abstract: The effects of actuator and sensor locations on transfer function zeros are investigated, using uniform bars and beams as generic models of flexible space structures. It is shown how finite element codes may be used directly to calculate transfer function zeros. The impulse response predicted by finite-dimensional models is compared with the exact impulse response predicted by the infinite dimensional models. It is shown that some flexible structures behave as if there were a direct transmission between actuator and sensor (equal numbers of zeros and poles in the transfer function). Finally, natural damping models for a vibrating beam are investigated since natural damping has a strong influence on the appropriate active control logic for a flexible structure.

Taut wire intrusion detection system and detectors useful therein

Abstract: A taut wire type intrusion detection system includes an actuator common to a group of the tensioned wires, which actuator is adapted to actuate a detector upon a change in tension in any of the wires. In some described embodiments, the common actuator includes an actuator wire coupling the plurality of wires to the detector; and in other described embodiments, the common actuator includes an actuator bar coupling the plurality of wires to the detector. Also described is a detector in the form of a ceramic piezoelectric force transducer which outputs an electrical signal proportional to the force applied by the actuator.

Fast-acting self-resetting hydride actuator

Abstract: A fast-acting, self-resetting hydride actuator comprising an enclosure containing hydrogen, and an actuating means communicating with the interior of the enclosure responsive to changes in pressure of the hydrogen gas and adapted to provide an actuating force based upon a change in pressure of the hydrogen gas. The actuator also comprises an electric resistance means inside the enclosure which includes a resistor element made in whole or in part of a hydridable electric conductor and means for passing electric current through said resistor element.

Thermally responsive actuators utilising shape memory, and exercising devices utilising the same

Abstract: The actuator comprises an elongate element 1, for example in the form of a twisted wire strand, of a shape memory alloy. The element 1 is provided with an elongate, flexible sleeve 2 in the form of a plastic tube. Permeable stops 7 may be provided to restrict axial movement of the element 1. Fluid can be passed through the tube 2 by means of an inlet 3 and an outlet 4. By varying the temperature of the fluid, the shape of the element 1 can be varied and in one preferred arrangement it changes between straight and curved states. Exercising devices for example for human limbs are also disclosed, these using the actuators together with a suitable supply of fluid. By alternating between hot and cold fluids, the devices can be made to move e.g. joints cyclically.