A sensor (S) is provided for determining the stroke of the piston rod (6) of a fluid cylinder, particularly a hydraulic or pneumatic cylinder. The sensor includes a lighting unit for illuminating a code applied on the surface of the piston rod and differing from said surface by color, a first camera unit with a first lens system for recording a first image of the illuminated code in a first scanning window, an evaluation unit for evaluating output signals of the first camera unit, and an interface for issuing the evaluated output signals as information regarding the position of the piston rod. Additionally, a second redundant camera unit is provided with a second lens system, which serves for recording a second image of the illuminated code in a second scanning window. According to the invention the second camera unit is arranged such that the second scanning window is spaced apart in the direction of the extension of the piston rod by a predetermined value from the first scanning window of the first camera unit. The output signals of the second camera unit are evaluated in an evaluation unit as information about the respective position by forming a difference, with in case of said difference being consistent with a predetermined value the output signal being considered information about the stroke of the piston rod, and in case of inconsistency of the difference with the predetermined value an error message being issued.

A fluid power control system for load handling mobile equipment includes a pair of hydraulic actuators for moving respective cooperating load-engaging members selectively toward or away from each other, or in a common direction, at respective asynchronous speeds to selectively attain either synchronous or asynchronous respective positions of the actuators. The actuators have sensors enabling a controller to monitor their respective movements and correct unintended differences in the actuators' respective movements, such as unintended differences in relative intended positions, speeds, or rates of change of speeds. Respective hydraulic valves responsive to the controller separately and nonsimultaneously decrease respective flows through the respective actuators to more accurately and rapidly correct differences from the intended relative movements of the actuators.

A cylinder-piston unit including: at least one cylinder including a tubular body (2); at least one piston (5) liable with a respective rod (5a), said piston (5) and said rod (5a) being translatable longitudinally in said tubular body (2) of said cylinder, at least one reference codification (C) extending for at least a section (dC) on the surface of said rod (5a), along the longitudinal axis of the same; at least detecting means (7), movable anchorable to said tubular body (2), faced, in use, towards said rod (5a) and suitable to detect said at least one reference codification (C) and to emit at the output at least a corresponding output electrical signal (s7), at least a reference zone (7c) of amplitude (d7c) delimited from said detecting means (7), said at least one reference codification (C) being detectable in correspondence to said at least one detection zone (7c); said at least one reference codification (C) including at least one plurality of adjacent sectors ( . . . , Si1, Si, Si+1, . . . ) extending along said longitudinal axis of said rod (5a), each of them for a section (dSi) of equal length; each sector (Si) includes a plurality of optical contrast zones (si1, si2, si3), each of them extending along said longitudinal axis of said rod (5a) for a respective section of extension (dsi1, dsi2, dsi3) such as the sum of the extensions of said sections of extensions (dsi1+dsi2 . . . ), in each sector (Si) is lower or equal to said amplitude (d7c) of said detecting zone (7c); said optical contrast zones (si1, si2, si3) being arranged in each sector (Si) according to the same sequence; and wherein in each sector (Si) at least one optical contrast zone (si1, si2, si3) shows said at least one respective section of extension (ds1, ds2, ds3) of different length compared to the length of the same section of extension in the other sectors (Si2, Si1, Si+1, Si+2, . . . ), therefore each sector (Si) remains univocally definable from the length of said at least one section of extension (dsi1, dsi2, dsi3) of said optical contrast zones (si1, si2, si3) in it included.

In order to secure a reached extension position of a piston rod (22, 22) of an in particular multi stage operating cylinder device (100) with at least one operating cylinder unit (50) not only through the operating pressure in the cylinder (1, 1) of the operating cylinder unit (50) but additionally mechanically, a mechanical safety through interlocking safety elements (4a, b) in the interior of the operating cylinder device (100) is provided which is activated exclusively by the operating pressure in the first pressure cavity and disengaged by a pressure in a second operating cavity.

A stroke detector includes: a cylinder tube; a piston rod configured to advance and retract with respect to the cylinder tube; a scale that is formed on the piston rod; and a first MR sensor and a second MR sensor that are provided on the cylinder tube. The scale has a first edge portion that is opposed to the first MR sensor and a second edge portion that extends at a different angle from that of the first edge portion and that is opposed to the second MR sensor.

The present invention relates to using a self calibrating and recalibrating 230, 925 optical sensors piston rod displacement. Self calibration enables field calibration of uncalibrated 230, 925 optical sensors. During operation, recalibration enables detecting and correcting for wear and damage of the 200 piston rod and/or 230, 925 optical sensors. 210 Calibration positions on the surface of the 200 piston rod are imaged by 230 optical sensors using laser or darkfield lenses designed for optical computer mice. Natural surface patterns can be used in locations where 210 calibration positions are required, which reduces or eliminates the need for marked 210 calibration positions. Marked 210 calibration positions are spatially unique encoded sequences used to determine the piston rod absolute position. Storing only the significant features of 210 calibration positions saves significant memory. The reduced memory requirements of each 210 calibration position enables the use of closely spaced or continuous 210 calibration positions. Multiple 210 calibration position features and multiple 230, 925 optical sensors together collectively provide immunity to localized 208 surface damage. Proximity sensors, 925 time of flight sensors and 031 cumulative relative displacement are used to estimate the 200 piston rod absolute displacement and reduce the number of spatially unique 210 calibration positions needed to compare in order to determine the piston rod absolute displacement.

Disclosed here is a system and method to control multiple eversion-based actuators using a single motor, or no motor, thereby reducing the size and cost of the multiple eversion-based actuators. An activation mechanism can include a motor rotating in an expansion direction, rotating shaft, clutch, brake, pressure source under high pressure, and/or valve. The activation mechanism can cause the actuators including a wound reel of material to unwind and lengthen. A retraction mechanism can include a motor rotating in a contraction direction opposite the expansion direction, rotating shaft, clutch, pressure source having low pressure, valve associated with the pressure source, and/or the passive retraction system. The retraction mechanism can cause the actuators to rewind and shorten.

Provided are a functional cylinder body, including a plurality of layers having magnetic patterns and non-magnetic patterns formed adjacently, and a manufacturing method therefor. The functional cylinder body comprises at least: a cylinder main body; a first functional pattern part, which includes first patterns and first functional patterns, the first patterns having first recess patterns and first non-recess patterns formed by forming recesses on a first material layer made of any one of a magnetic material and a non-magnetic material, the first functional patterns being made of any one of the magnetic material and the non-magnetic material embedded in the first recess patterns; and a second functional pattern part, which is formed in a position of the cylinder main body shallower than a position of the first recess patterns and has magnetic patterns of the magnetic material and non-magnetic patterns of the non-magnetic material formed adjacently.

The linear measuring system includes one part of a (usually steel) rod, beam or strip that is profiled with a trapezium like (subset of a) De Bruijn sequence. Each element of the alphabet is represented by a discrete height of the profile. The profile can be coated with a material with low magnetic susceptibility to enable the application on a piston rod of a pressure medium cylinder. The second part of the measuring system reads the subsequences of the main sequence by using the signals of arrays of linear Hall effect sensors, placed in a magnetic field as input for a signal processing algorithm. With a look-up table, the position of this second part of the measuring system with respect to the profile is determined. An interpolation algorithm can be used to improve the resolution to well below the sequence pitch.

A sensor (S) is provided for determining the stroke of the piston rod (6) of a fluid cylinder, particularly a hydraulic or pneumatic cylinder. The sensor includes a lighting unit for illuminating a code applied on the surface of the piston rod and differing from said surface by color, a first camera unit with a first lens system for recording a first image of the illuminated code in a first scanning window, an evaluation unit for evaluating output signals of the first camera unit, and an interface for issuing the evaluated output signals as information regarding the position of the piston rod. Additionally, a second redundant camera unit is provided with a second lens system, which serves for recording a second image of the illuminated code in a second scanning window. According to the invention the second camera unit is arranged such that the second scanning window is spaced apart in the direction of the extension of the piston rod by a predetermined value from the first scanning window of the first camera unit. The output signals of the second camera unit are evaluated in an evaluation unit as information about the respective position by forming a difference, with in case of said difference being consistent with a predetermined value the output signal being considered information about the stroke of the piston rod, and in case of inconsistency of the difference with the predetermined value an error message being issued.