Abstract: An apparatus for positioning a work implement in predetermined operative attitudes, including a valve body mounting a piston which is operable for movement through a range of selective operative positions, and which is further connected to the work implement; a pair of pulse valves mounted on the valve body and connected in fluid communication with the piston and operable selectively to supply a source of hydraulic pressure to the valve body; and an actuator is connected in signal transmitting relation to the pair of pulse valves and is adapted selectively to actuate same thereby causing the selective release of hydraulic pressure to position the piston, and thus the work implement in a selected operable attitude.

Abstract: A modular handling system is assembled from a plurality of linear drive, rotary drive, or tool modules. The linear drive used as a cylinder block with a cylindrical bore therein and cylinder heads sealing off the cylindrical bore. A pneumatically actuated piston travels within the cylindrical bore. A carriage runs on the cylinder block and is connected with the piston by means of a flexible belt attached to both the piston and the carriage and deflected by deflection rollers mounted on the cylinder heads. Cartridge-type valves are integrated into both cylinder heads for controlling displacement of the piston. One of the cartridge valves is made as a pressure-servo-valve allowing linear control of valve output pressure vs. valve operating current. The cartridge valve integrated into the opposite cylinder head may be either another pressure-servo-valve or a displacement-servo-valve allowing linear control of valve spool displacement vs. valve operating current.

Abstract: An electrohydraulic servo valve employing a linear force motor having a floating coil and armature driven by a high frequency excitation signal modulated to change its average DC component. A servo loop controller modulates the excitation signal in response to feedback signals from the servo valve or a hydraulic actuator controlled by the servo valve.

Abstract: An enclosed adjustable servo-actuator is provided. This servo-actuator includes an elongated hollow cylinder; a first closed end member; a second closed end member; a through passageway is provided in each closed end member; an enclosed housing attached exterior of the hollow cylinder at or near the center of the cylinder, said housing adapted to comunicate with the interior of the hollow cylinder; an elongated piston assembly is slidably carries interior of said hollow cylinder; A torque arm is arrayed to engage said piston assembly by means of a closed-end transverse groove provided in said piston assembly; an output shaft is journaled in said enclosed housing, said output shaft engages said torque arm for converting the linear displacement of the piston to an arcuate rotation of said output shaft; and an adjustment means is provided to selectively limit the arcuate rotation of the output shaft.

Abstract: The object of the invention is to improve the position and feed or advance regulation of a hydraulic drive which is controlled by a proportional valve. In a first compensation circuit the flow characteristic of the proportional valve is linearized to obtain very small feed rates and a high control amplification. In a second compensation circuit the positioning error of the drive arising from the necessary overlapping of the proportional valve is compensated.

Abstract: An electrohydraulic control system includes an actuator having a cylinder and a piston variably positionable therewithin. An electrohydaulic valve is responsive to valve control signals for coupling the actuator to a source of hydraulic fluid. A coaxial transmission line extends through the actuator, and includes an outer conductor formed by the actuator cylinder and a center conductor operatively coupled to the piston, such that length of the coaxial transmission line is effectively directly determined by position of the piston within the cylinder. An rf generator is coupled to the coaxial transmission line for launching rf energy therewithin, and valve control electronics is responsive to rf energy reflected by the coaxial transmission line for indicating position of the piston within the cylinder and generating electronic control signals to the valve. A second coaxial transmission line of fixed length is connected the valve and actuator so that the hydraulic fluid flows therethrough.

Abstract: A time division multiplexed (TDM) hydraulic control system having a plurality of channels, each channel having a servo actuator. Electrical demand signals are arranged in TDM sequence and applied to a single multiplexed pilot valve so that the pilot valve produces a plurality of hydraulic signals. Commutator means are associated with the pilot valve for distributing the hydraulic signals to the associated channels. In order to achieve useful output flow rates in the channels, each channel includes a second stage valve which integrates the hydraulic signals for its channel to produce an output flow rate which is a function of the integrated signal. The flow rates are continuously produced (as compared to the multiplexed output signals) and are coupled to actuators in the channels for controllably adjusting the position thereof. Feedback means associated with the actuators includes rate feedback for stabilizing the multiplexed control loops.

Abstract: A time multiplexed hydraulic control system in which a multiple section dog valve is multiplexed among a plurality of channels. An electrical actuator on the dog valve controls pilot means. The pilot means is associated with a plurality of followers, one for each channel, and each follower controls the flow rate through an associated output port. Multiplexing means in the dog valve sequentially supplies fluid to the pilot means for sequentially positioning then locking the respective followers. Thus, each channel has continuous hydraulic flow based on the position of its dedicated follower, with the followers being repositioned on a multiplexed basis in associated time slots.

Abstract: An electrohydraulic control system includes an actuator having a cylinder and a piston variably positionable therewithin. An electrohydraulic valve is responsive to valve control signals for coupling the actuator to a source of hydraulic fluid. A coaxial transmission line extends through the actuator, and includes an outer conductor formed by the actuator cylinder and a center conductor operatively coupled to the piston such that length of the coaxial transmission line is effectively directly determined by position of the piston within the cylinder. An rf generator is coupled by an antenna to the coaxial transmission line for launching rf energy therewithin, and valve control electronics is responsive to rf energy reflected by the coaxial transmission line for indicating position of the piston within the cylinder and generating electronic control signals to the valve.

Abstract: A novel digital servo valve system for use in displacing an actuator is capable of operating either in closed or open loop mode. The system includes a controller that compares computed values of actuator parameters with preselected parameter values and iteratively determines therefrom command signals for the servo valve. The servo valve is characterized by a ball screw mechanism that eliminates mechanical backlash and a torsion bar which increases radial and angular compliance. A servo valve provided according to the present invention also displays reduced flow forces using a simple, inexpensive valve body in combination with a uniquely configured displaceable spool.

Abstract: A 3/2 proportional control valve is provided with an actuating piston which is subjected to the control pressure set in a pilot valve. The area relationships of the actuating piston are so chosen that at the actuating piston a high pressure gradient obtains and the adjustment dynamics of the regulating piston are increased.

Abstract: A fluid apparatus includes a pneumatic cylinder having a main body, a piston, and a hollow rod. A ball screw shaft engaged with a ball nut fixed to the piston is rotatably and axially unmovably mounted in the cylinder and extends in the hollow rod. A magnetic brake for braking the ball screw shaft is fixed to an end portion of the main body of the cylinder. The number of revolutions of the ball screw shaft is detected and outputted in a signal form by a rotary encoder. A primary solenoid controlled valve reciprocates the piston by connecting a pressure source either to a first or second port of the cyliner, and secondary solenoid controlled valves connect a pressure source either to a first braking pressure port or to a second braking pressure port.

Abstract: A hydraulic cylinder-piston unit comprises primary cylinder-piston unit with an integrated position regulation and with a primary cylinder and a primary piston movable in the primary cylinder, two displacement chambers in the primary cylinder and including two displacement pistons, a displacement piston rod connecting the displacement pistons with one another, and a separating wall, and differential cylinder-piston unit formed by the primary piston and having a differential cylinder provided with working chambers.

Abstract: For converting a stepwise translation movement into a continuous translation movement and arrangement and a method is provided which have at least two fluid-operated cylinder-piston units with cylinders are rigidly mechanically connected with one another and pistons movable in the cylinders between end positions and having piston rods, removably arranging clamping mechanisms on the pistons of the cylinder-piston units, arranging end position sensors in the regions of the end positions of the piston of a respective one of the cylinder-piston units, arranging end position pre-signal sensors so that they are axially spaced relative to the end position sensors, connecting the sensors with electronic a control unit, and producing by the electronic control unit signals for supplying a working fluid to the cylinders of the cylinder-piston units in an alternating manner.

Abstract: A time division multiplexed (TDM) hydraulic control system having a plurality of channels, each channel having a servo actuator. Electrical demand signals are arranged in TDM sequence and applied to a pilot valve so that the pilot valve produces a plurality of hydraulic signals. The hydraulic signals in turn are coupled to a separate commutator which distributes the hydraulic signals to the associated channels. The pilot valve is arranged with a full annular output port to maximize the port area and thereby the flow rate to the channels. The commutator size and port area is coordinated to that of the pilot valve to minimize pressure drop across the commutator and to maximize flow rate to the channels.

Abstract: A pre-set fluid actuator for setting the roll gap of a rolling mill having a transducer for detecting actuator movement and an electrohydraulic servovalve for controlling its position, a control system for compensating for the compressibility of the actuator fluid caused by the rolling force in a manner that requires no operation of the servovalve by creating a pre-set anticipating compression compensation signal and reducing the output of this signal by the output of a signal representing the actual fluid compression caused by the actual rolling force.

Abstract: A system for the control of a fluid flow control valve which controls the supply of fluid to an actuator to control the movement of a component such as a tractor implement hitch in response to a selected operating parameter such as hitch position or draft force. The system enables the desired value of the selected parameter to be set and this desired value is compared with the actual sensed value of the parameter to provide a parameter error signal. A start-up control function is provided to improve the initial speed of response of the system. The start-up control function is arranged on each detection of a parameter error signal to apply a start-up signal to the valve to initiate movement of the component and, if no movement results, to increase the start-up signal until movement of the component is detected whereupon the increase in the start-up signal is stopped and the magnitude of the signal applied to the valve is dependent on the parameter error signal so as to tend to reduce the error signal to zero.

Abstract: A system for positioning equipment quickly and accurately over a plurality of desired positions by employing a "long move" mode of operation and a "short move" mode of operation to adapt the operation of the positioning system to variable and changing conditions. The system generally includes a microprocessor as the controlling means, a controlled valving means, a pressure source coupled to the valving means, an encoder sensing means and a positioning means defined by a pneumatic cylinder.

Abstract: A rotary actuator includes a shaft rotatably mounted on a body, and a servovalve arranged to operate a vane motor for selectively rotating the shaft relative to the body. A portion of the shaft extends beyond the body. Supply and return passages are provided to the body and shaft so that fluid power supplied to the body is supplied to the servovalve and is also available at the end of the shaft beyond the body. Two or more such rotary actuators may be connected by intermediate brackets to provide a wrist actuator capable of movement about axes.

Abstract: The invention relates to a method and a device for reducing the piston speed in a piston and cylinder assembly (1), as the piston approaches the end position. The piston end position is sensed, and a signal is generated for starting the end position dampening. Dampening is effected in two steps. In the first step (14), a time delay is provided and in the next step (15), the actual braking (retardation) of the piston is effected.The invention also comprises an electronic braking device comprising a dampening activation unit (13) which is connected to transducers (6), a braking delay unit (14) connected to the unit (13) and also to the control lever (5) at issue and a reference signal source, as well as a braking unit (15) connected to the delay unit (14) and adapted, upon activation, to provide a signal (U) to a setting system (3) for controlling the supply of pressure fluid to the piston and cylinder assembly (1).

Abstract: A hydraulic operating apparatus for a circuit interrupter comprises a conversion unit for converting input information from the exterior concerning a speed control pattern into an electrical signal for driving a linear or servo motor according to the closing and interrupting commands, the motor drive signal provided from the converting means being transmitted to the motor such that the displacement of the motor causes the hydraulic control valve apparatus to be operated to switch the fluid passages to selectively drive the hydraulic cylinder in different directions, and that the position during the switching of the hydraulic control valve driven by the motor is made different from the final stop position at its interruption or closed state to provide a throttle effect of a throttle in the hydraulic control valve thereby controlling the speed of the hydraulic cylinder.

Abstract: A control system for a two way acting hydraulic servomotor wherein the servomotor is connected in the diagonal of a bridge circuit that includes four magnetic valves with a pair of the valves being normally open in a non-energized condition being connected to the one end of the servomotor and to the container and a second pair of the valves being normally closed in a deenergized condition being connected to the opposite end of the servomotor and to a pressure source. Circuitry provides pulse trains that are modulatable to control the operation of the magnetic valves and thereby the application of pressurized fluid to the opposite ends of the servomotor.

Abstract: A control system for a working machine which has a boom equipped with a working implement at its forward end and pivoted to a vehicle body movably about a vertical axis, and control valve for controlling the movement of the boom. The system comprises a variable resistor for setting a target position where the boom is to be stopped to produce a setting signal, a sensor for detecting the moved position of the boom to produce a detection signal, differential device for determining the difference between the setting signal and the detection signal to produce a difference signal, a detector for detecting the direction of movement of the boom from the magnitude of the difference signal, a pulse-width modulator for subjecting the difference signal to pulse-width modulation to produce a pulse signal, and a driver for driving the control valve by the pulse signal in the detected direction in proportion to the difference signal.

Abstract: The invention relates to a piston and cylinder unit whose piston rod is provided with a rack extending along it. The rack is in mesh with a ring of teeth (such as the teeth of a toothed belt or the teeth of a gear wheel) adapted to revolve about one axis (in the case of a gear wheel) or about at least two axes (in the case of a toothed belt). Such meshing engagement takes place in every position of the piston rod. When the piston rod is moved in the direction of its length the ring of teeth revolves about at least one axis and rotates a means for influencing the motion of the piston rod. Such means may for example be a liquid brake or a synchro transmitter connected with a NC unit controlling the supply of driving fluid to the piston and cylinder unit.

Abstract: Agricultural vehicles have heretofore lacked an adaptive implement hitch control and have correspondingly suffered from poor controllability of the hitch when the mass of the implement is varied significantly. The apparatus employs a sensor connected to and movable with the hitch such that a variable magnitude electrical signal is delivered which corresponds to the instantaneous hitch position. This signal is electronically differentiated to produce a signal indicative of actual hitch velocity. The hitch position and velocity signals are both used as feedback signals to close the control loop of the control and thereby provide an adaptive hitch velocity control.

Abstract: Apparatus and method for dispensing fluid materials wherein the fluid is discharged from a nozzle at a rate controlled by a metering valve having a seat and a stem moveable with respect to the seat to modulate the flow. A servo-actuator connected in a feedback control loop is used to position the valve stem with respect to its seat in accordance with a control signal. The control signal is derived in accordance with the difference between a driving signal representing a desired flow rate and the sum of a pair of feedback signals. One feedback signal represents the actual flow rate while the other feedback signal is correlated to both the relative velocity and position of the stem with respect to the seat. The position-dependent velocity signal is generated by a transducer comprising a magnet and a coil influencable by the field of the magnet as the magnet and coil move relative one another.

Abstract: The object of the invention is to improve the position and feed or advance regulation of a hydraulic drive which is controlled by a proportional valve. In a first compensation circuit the flow characteristic of the proportional valve is linearized to obtain very small feed rates and a high control amplification. In a second compensation circuit the positioning error of the drive arising from the necessary overlapping of the proportional valve is compensated.

Abstract: In a dynamic characteristic compensating device for an electrical hydraulic servo actuator, a differential pressure detecting piston is displaced in proportion to the difference in pressure between two hydraulic operating chambers provided on opposite sides of the main piston in the actuator, and a speed detector converts the displacement of the differential pressure detecting piston into an electrical signal. The electrical signal is fed back to the control signal input circuit side of an electrical hydraulic servo valve, to control the valve in such a manner that differential pressure variations due to disturbances applied to the actuator are canceled out by the feedback signal.

Abstract: An electronic tractor hitch control system in which the position of an implement hitch relative to a tractor can be set using a main control operable by a tractor operator from his normal location on the tractor and can also be set using a secondary control located at a location remote from the normal operator's location, such as on the rear of the tractor fenders. The system is arranged so that any implement position signal set using the secondary control is opposed by a smaller hitch positioning signal generated within the system so that the speed of movement of the hitch in response to hitch positions set using the secondary control is moderated. The system also includes circuitry for detecting short circuits in parts of the system located in vulnerable locations.

Abstract: A hydraulic actuator for automobiles includes a hydraulic actuator body composed of a hydraulic cylinder and a plurality of solenoid valves, and an electric control circuit disposed adjacent to the hydraulic actuator body for controlling the operation of the solenoid valves. The electric control circuit operates upon receipt of an execution signal, an analog desired-position signal, and an actual-position signal delivered from a position sensor. The hydraulic actuator thus constructed has an improved degree of compatibility.

Abstract: A spindle carrier, which is movable vertically by an electric servo motor through a relatively long ball screw, has a substantially constant counterbalance force maintained on it irrespective of whether it is moving up or down. This prevents compression or tension of the ball screw. The counterbalance force is maintained substantially constant through sensing the load on the spindle carrier and using the sensed load to vary the hydraulic pressure applied to a piston within a hydraulic cylinder and connected through a chain to the spindle carrier to apply the counterbalance force.

Abstract: A dual redundant servomechanism for moving aircraft control surfaces is disclosed. The servomechanism is of the type whose input commands, from the pilot of the aircraft, are transmitted electrically. Force fight, which is associated with such dual servomechanisms when they are connected to a common aircraft control surface, is minimized. This is accomplished by providing the control system for each servomechanism with input signals which are electrically summed. Each control system includes electrical transducers which provide a signal indicative of actuator position and the pressure associated with the hydraulic motor used in each servomechanism.

Abstract: A double-acting accelerated forging hammer and method of operation are disclosed. The hammer is of the type having a vertically oriented cylinder, a piston slidably mounted within the cylinder having a downwardly depending piston rod extending along the cylinder and attached to a hammer. A gas accumulator communicates with the cylinder above the piston for supplying gas under pressure thereto during a forging stroke, and a fluid accumulator communicating with the cylinder below the piston for supplying fluid thereto at a higher pressure than the gas to dirve the piston upwardly during a return stroke. A fluid tank supplies fluid to recharge the accumulator and receives fluid from the cylinder during the forging stroke. Variable valves control the rate of fluid flow from the cylinder and thereby control the rate at which the piston descends within the cylinder.

Abstract: A pneumatic drive mechanism for use with positioning apparatus or the like, having a drive housing, a drive element such as diaphragm disk, piston or the like, movably seated therein and rigidly connected to a drive rod or similar device. The drive element is responsive to compressed air on one side thereof and to forces from at least one spring operating in opposed action to the compressed air. The spring is arranged within the drive housing. The drive mechanism also has a signal processing device such as a position controller, position encoder, limit signal generator, solenoid valve or i/p converter or similar devices. The signal processing device or devices are integrated within the drive housing in an accomodation space which is free of the spring or springs, of the drive rod and of the drive element.

Abstract: A control system is provided for a hydraulic actuating system having a multi-phase stepping motor with a driver therefor which supplies and controls DC current through each of the motor windings such that no current is induced into the control winding from adjacent windings. The stepping motor precisely controls the rotation of an eccentric cam engaging an actuating plunger which actuates a control valve of the hydraulic actuating system. The driver receives control signals from a computer programmed to calculate, from user input command signals indicative of the desired system condition, and generate those control signals which most quickly achieve a rough approximation of the desired system condition. After this rough approximation is attained, the computer generates new control signals for the driver as a function of feedback signals and/or system component characteristics so as to precisely achieve the desired system condition.

Abstract: A control apparatus having a boom control system for controlling the movement of a liftable boom supported by a vehicle body and a working device control system for controlling a working device pivoted to the boom. Each of the control system includes a proportional solenoid valve and comprises an instruction circuit for producing an instruction signal in accordance with the amount of manipulation of an operating lever, discriminating circuit for determining the direction of operation of the valve from the instruction signal, a reference signal generator, a comparison circuit for comparing the instruction signal with the reference signal from the generator to obtain a pulse signal of a width in proportion to the amount of manipulation, and drive circuit for converting the pulse signal into a current to drive the valve in the direction determined by the discriminating circuit. The boom, as well as the working device, is movable at a speed corresponding to the amount of manipulation of the operating lever.

Abstract: Method and apparatus of controlling and positioning a fluid actuator by supplying pressurized fluid to right and left actuating chambers of the actuator through an on-off control valves. To drive and position the actuator rapidly and accurately, the actuator can be driven at a higher speed by an initial driving force until it reaches near the desired position and continuously moved at a low speed by gradually increasing the fluid pressure to be supplied to the right and left actuating chambers of the actuator. The initial driving force in the high-speed range becomes maximum when the pressure is applied to one of the right and left actuating chambers while at the same time the other actuating chamber is exhausted. In the low-speed range and near the target position, the one actuating chamber is continuously supplied with the pressure while at the same time the other actuating chamber is gradually closed.

Abstract: A pump supplies via in each case a directional valve with associated pressure balance fluid or pressure medium to a plurality of loads. When the pump power is not sufficient a proportional quantity reduction is achieved at all loads in that the control voltages of the control members for electrical actuation of the directional valves are supplied to a summation stage and the sum voltage is compared in a comparison stage with a limit value corresponding to the maximum pump displacement, whereupon when the limit value is exceeded a control signal is generated with which the stroke of the driven directional valves is reduced.

Abstract: An electrohydraulic servo system which includes an actuator having a cylinder and a piston variably positioned therewithin, a servo valve responsive to valve control signals for coupling the actuator to a source of hydraulic fluid, and control electronics responsive to piston position for generating the valve control signals. A variable frequency rf generator is coupled through associated directional couplers to a pair of antennas which are positioned within the actuator cylinder 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.

Abstract: A control for a press for controlling the flow of fluid to two hydraulic actuators which applies a desired working force to or which positions the press platen in a desired position including a sub-control for introducing first and second super-imposed oscillations on the fluid of the actuators of equal amplitude and opposite phase to reduce internal friction in the actuators without disturbing the desired applied force or position of the platen.

Abstract: A linear actuator (42) includes a housing (44), and a linearly displaceable piston (46) having a shaft (48) with a gradated position scale (60) and a gradated direction scale (62) disposed by ion implantation on a casing (50) of the shaft, in axial alignment (49) with the shaft stroke. Proximity sensors (64, 66) mounted in the housing sense movement in the position of the scales to provide sensed shaft position signals (68) and sense shaft direction signals (70).

Abstract: An electrohydraulic servo system which includes a linear actuator having a cylinder and a piston variably positioned therewithin, a servo valve responsive to valve control signals for coupling the actuator to a source of hydraulic fluid, and control electronics responsive to piston position for generating the valve control signals. A coaxial transmission line is formed within the linear actuator to include a center conductor coaxial with the actuator and an outer conductor. A bead of ferrite or other suitable magnetically permeable material is coupled to the piston and surrounds the center conductor of the transmission line for altering impedance characteristics of the transmission line as a function of position of the piston within the cylinder.

Abstract: A load sensing circuit of a load responsive direction control valve including a device for sensing load pressure signals identifying those load pressure signals as positive or negative and transmitting those identified positive or negative load pressure signals to the throttling compensator control of the load responsive valve, while also transmitting the positive load pressure signal to the pump control. The load pressure signals from individual cylinder ports, together with the signals related to the direction of displacement of the controlled load, are transmitted electrically to an electrical logic circuit, which identifies the load pressures as positive or negative and generates the required electrical signals to the electrohydraulic controls, which connect the positive or negative load pressure to throttling compensator controls of the load responsive direction and flow control valve.

Abstract: An electrohydraulic system includes a plurality of electrohydraulic devices individually controlled by microprocessor-based control electronics. The device controllers are connected in common by a bidirectional serial data bus to a master controller for coordinating operation of the various devices. Internal programming within the master controller establishes a repetitive time-sequence of windows for communications with the various device controllers for downloading control signals and parameters, and for uploading data indicative of system status and operation. The various device controllers include internal programming for operating the associated hydraulic devices as a function of control signals and parameters received from the master controller.

Abstract: The apparatus disclosed herein provides controlled operation of a pneumatic actuator by effecting charging and discharging of the actuator through an intermediate step volume, the pressure in the step volume being regulated as a respective function of the existing pressure in the actuator during charging and discharging.

Abstract: A control for the speed of rotation of a hydrostatic machine in which the controlled variable and generated in a speed controller and is made up of a proportional component and an integrating component is limited by a limiting signal which is also made up of a predetermined basic value and a ramp signal behaving proportionally to the actual pivot angle of the hydrostatic machine. The limiting signal thus limits the output signal of the speed controller so that a rapid response behaviour is obtained and fluctuations in the settling to the desired speed are reduced.

Abstract: A pneumatic control system for a reversible stepping actuator has an analog pneumatic control signal and an analog signal indicative of actual position of the actuator. Imbalance in these signals opens one or the other of a pair of comparator valves having inlets connected to a source of pneumatic pressure. Opening of either of the comparator valves enables a pulse timer which converts the pneumatic pressure from either of the comparator valves to pulses of pneumatic pressure applied to one or the other of the operators of the reversible stepping actuator. An oscillating pneumatic timer may be used to produce the pressure pulses, or an electric timer can be used to "chop" one of the pneumatic pressures into periodic pulses.

Abstract: A system and method for remotely measuring and linearizing flow characteristics, specifically velocity characteristics, of an electrohydraulic servo valve and actuator system. A plurality of raw command signals are generated in sequence, and corresponding motion data at the valve and load (including the actuator) are measured and stored. A linearized characteristic is then generated corresponding to the range of motions measured, and a look-up table is generated which relates raw command signals to command signals necessary to obtain the desired linear motion characteristics.

Abstract: A tool, in particular a lapping wheel, is to be positioned by a hydraulic drive cylinder and subsequently pressed against a workpiece. For this purpose a position control and a pressure or force control is provided. The weight change of the lapping disk subjected to wear is automatically detected by measuring the pressure value which is necessary to keep the weight in a state of suspension without support. The pressure value is stored and in the subsequent pressure regulating operation fed as compensating parameter to the pressure control circuit.

Abstract: The present invention uses an input multiplexer for selecting a plurality of input signals, a fluid multiplexer for selectively delivering a control output to a plurality of devices to be controlled, a detecting multiplexer for selecting detected signals indicative of the condition in which the devices respond, a controller for controlling the multiplexers for successive and repeated selective operations, for effecting a controlling arithmetic operation on an input signal fed through the input multiplexer and a detected signal fed through the detecting multiplexer, and for delivering a control signal resulting from the controlling arithmetic operation, and an electropneumatic transducer for converting the control signal to a pneumatic pressure and issuing the pneumatic pressure as an input to the fluid multiplexer.