EP0115008A2 — Positioning control system for a fluid powered cy…

Claim 1

Independent Claim 178 words

A piston rod position detection device for a fluid powered cylinder comprising: a coil assembly including primary coils disposed at predetermined locations axially spaced from one another and secondary coils provided in association with said primary coils, said coil assembly being fixed at one end of said cylinder in such a manner that said rod is slidably disposed through a space in said primary and secondary coils; a plurality of rings made of magnetic substance and provided on said rod with a predetermined axial interval therebetween; a circuit for exciting each of said primary coils with one of reference AC signals which are out of phase with one another; a circuit for summing outputs of said secondary coils and thereby producing an output signal resulting by phase shifting the reference AC signals in accordance with a relative linear position of said rod; and a circuit for detecting a phase difference between a predetermined one of the reference AC signal and the output signal of said summing circuit to obtain detected phase difference data as piston rod position data.

Claim 2

Dependent Claim 178 words

A piston rod position detection device for a fluid powered cylinder comprising: a coil assembly including primary coils disposed at predetermined locations axially spaced from one another and secondary coils provided in association with said primary coils, said coil assembly being fixed at one end of said cylinder in such a manner that said rod is slidably disposed through a space in said primary and secondary coils; a plurality of rings made of magnetic substance and provided on said rod with a predetermined axial interval therebetween; a circuit for exciting each of said primary coils with one of reference AC signals which are out of phase with one another; a circuit for summing outputs of said secondary coils and thereby producing an output signal resulting by phase shifting the reference AC signals in accordance with a relative linear position of said rod; and a circuit for detecting a phase difference between a predetermined one of the reference AC signal and the output signal of said summing circuit to obtain detected phase difference data as piston rod position data.

Claim 3

Dependent Claim 41 words

A piston rod position detection device as defined in Claim 1 wherein said rod is made of non-magnetic material, said respective rings are of a predetermined length and said rings and annular non-magnetic spacers are axially alternately provided about said rod.

Claim 4

Dependent Claim 35 words

A piston rod position detection device as defined in Claim 2 wherein a sleeve made of a non-magnetic substance covers said rings and spacers provided about said rod over the entire length of said rod.

Claim 5

Dependent Claim 98 words

A piston rod position detection device as defined in. any of Claims 1 to 3 wherein each of said rings of magnetic substance has a predetermined length to cause reluctance of a magnetic path passing through each one of said primary coils and each one of said associated secondary coils to be changed in accordance with the relative linear position of said ring and each of said primary coils is disposed in a predetermined location such that the phase of the reluctance change for each of said primary coils is shifted from one another by a predetermined amount.

Claim 6

Dependent Claim 144 words

A piston rod position detection device as defined in Claim 4 wherein said primary coils and said secondary coils are divided into coil groups of four phases and disposed in such a manner that the phase of the reluctance change for each of said coil groups responsive to the relative linear position of said rings is shifted by a predetermined amount from its adjacent coil groups, primary coils of two coil groups among said coil groups which are spaced from each other by 180° in the reluctance change being excited in opposite phases by a sine wave signal used as the reference AC signal and primary coils of two other coil groups among said coil groups which are spaced from each other by 180° in the reluctance change being excited in opposite phase by a cosine wave signal used as the reference AC signal.

Claim 7

Dependent Claim 229 words

A piston rod position detection device for a fluid powered cylinder comprising: a stator including poles disposed with a predetermined interval therebetween in the circumferential direction and being respectively provided with a primary coil and a secondary coil wound thereon, said stator being fixed on one end of said cylinder in such a manner that said rod is slidably disposed through a space defined by said poles with a predetermined gap being formed between said rod and said poles; projections provided, with a predetermined axial pitch, at least on the surface of said rod opposing each of said poles in such a manner that a predetermined difference is produced among said poles in the corresponding relationship between said projections and end portions of said poles, said rod being made of magnetic substance; a circuit for exciting each of said primary coils with one of reference AC signals which are out of phase with adjacent poles by a predetermined electrical angle; a circuit for summing outputs of said secondary coils and thereby generating an output signal resulting by phase shifting the reference AC signals in accordance with a relative linear position of said rod; and a circuit for detecting a phase difference between a predetermined one of the reference AC signal and the output signal of said summing circuit to obtain detected phase difference data as piston rod position data.

Claim 8

Dependent Claim 229 words

A piston rod position detection device for a fluid powered cylinder comprising: a stator including poles disposed with a predetermined interval therebetween in the circumferential direction and being respectively provided with a primary coil and a secondary coil wound thereon, said stator being fixed on one end of said cylinder in such a manner that said rod is slidably disposed through a space defined by said poles with a predetermined gap being formed between said rod and said poles; projections provided, with a predetermined axial pitch, at least on the surface of said rod opposing each of said poles in such a manner that a predetermined difference is produced among said poles in the corresponding relationship between said projections and end portions of said poles, said rod being made of magnetic substance; a circuit for exciting each of said primary coils with one of reference AC signals which are out of phase with adjacent poles by a predetermined electrical angle; a circuit for summing outputs of said secondary coils and thereby generating an output signal resulting by phase shifting the reference AC signals in accordance with a relative linear position of said rod; and a circuit for detecting a phase difference between a predetermined one of the reference AC signal and the output signal of said summing circuit to obtain detected phase difference data as piston rod position data.

Claim 9

Dependent Claim 31 words

A piston rod position detection device as defined in Claim 6 wherein said rod is provided on the periphery thereof with a helical projection of a predetermined pitch as said projection.

Claim 10

Dependent Claim 23 words

A piston rod position detection device as defined in Claim 6 or 7 wherein a sleeve made of non-magnetic substance covers said rod.

Claim 11

Dependent Claim 152 words

A positioning control device for a fluid powered cylinder comprising: position detection means for detecting a relative linear position of a piston rod in said cylinder; velocity detection means for detecting the velocity of movement of said rod; acceleration detection means for detecting the acceleration of movement of said rod; setting means for setting a positioning target value; determination means for determining an estimated amount of overrun by employing the detected velocity and acceleration data; compensation means for modifying at least one of the value of position data obtained by said position detection means and the positioning target value in accordance with the estimated amount of overrun determined by said determination means; comparison means for comparing the position data and the. target value after the modification by said compensation means; and drive control means for controlling the movement of said cylinder in accordance with the result of comparison by said comparison means.

Claim 12

Dependent Claim 152 words

A positioning control device for a fluid powered cylinder comprising: position detection means for detecting a relative linear position of a piston rod in said cylinder; velocity detection means for detecting the velocity of movement of said rod; acceleration detection means for detecting the acceleration of movement of said rod; setting means for setting a positioning target value; determination means for determining an estimated amount of overrun by employing the detected velocity and acceleration data; compensation means for modifying at least one of the value of position data obtained by said position detection means and the positioning target value in accordance with the estimated amount of overrun determined by said determination means; comparison means for comparing the position data and the. target value after the modification by said compensation means; and drive control means for controlling the movement of said cylinder in accordance with the result of comparison by said comparison means.

Claim 13

Dependent Claim 27 words

A positioning control device as defined in Claim 9 wherein said cylinder is provided with a brake and said drive control means controls at least said brake.

Claim 14

Dependent Claim 89 words

A positioning control device as defined in Claim 9 or 10 wherein said determination means comprises: a first memory device for prestoring amounts of overrun corresponding to various velocities and provides first overrun amount data in response to the detected velocity; a second memory device for prestoring amounts of overrun corresponding to various accelerations and provides second overrun amount data in response to the detected acceleration; and an operation circuit for determining the estimated amount of overrun by a predetermined operation employing said first and second overrun amount data

Claim 15

Dependent Claim 44 words

A positioning control device as defined in Claim 11 wherein said operation circuit obtains the estimated overrun amount by adding or subtracting the first and second overrun amount data at a predetermined ratio in accordance with the target value set by said setting means.

Claim 16

Dependent Claim 68 words

A positioning control device as defined in Claim 11 wherein said operation circuit selects the second overrun amount data when the target value set by setting means corresponds to a relatively short amount of displacement within a predetermined range and selects the first overrun amount data when the target value does not corresponds to that amount, thereby determining the estimated overrun amount in accordance with the selected data.

Claim 17

Dependent Claim 159 words

A positioning control device as defined in any one of Claims 9 to 13 wherein said drive control means controls the movement of said cylinder in accordance with the result of comparison to position said cylinder to a position corresponding to the target value and wherein said device further comprises: means for detecting an error of an actual stop position of said cylinder relative to the target value each time the positioning control has been completed; memory means for storing offset data associated with the detected error; and data value correction means provided in one or more of signal paths including said determination means, compensation means and comparison means, the offset data stored in said memory means being read out during a next positioning control and used as a correction parameter in said data value correction means to correct one or more of the estimated overrun amount, position data and target value data in accordance with the offset data.

Claim 18

Dependent Claim 52 words

A positioning control device as defined in Claim 14 wherein said memory means stores the offset data using the target value as address data and the offset data is read from said memory means during the next positioning control using the target value set for the next positioning control as address data.

Claim 19

Dependent Claim 185 words

A positioning control device as defined in any of Claims 9 to 14 wherein said position detection means comprises: a coil assembly including primary coils disposed at predetermined locations axially spaced from one another and secondary coils provided in association with said primary coils, said coil assembly being fixed at one end of said cylinder in such a manner that said rod is slidably disposed through a space in said primary and secondary coils; a plurality of rings made of magnetic substance and provided on said rod with a predetermined axial interval therebetween; a circuit for exciting each of said primary coils with one of reference AC signals which are out of phase with one another; a circuit for summing outputs of said secondary coils and thereby producing an output signal resulting by phase shifting the reference AC signals in accordance with a relative linear position of said rod; and a circuit for detecting a phase difference between a predetermined one of the reference AC signal and the output signal of said summing circuit to obtain detected phase difference data as piston rod position data.

Claim 20

Dependent Claim 236 words

A positioning control device as defined in any of Claims 9 to 14 wherein said position detection means comprises: a stator including poles disposed with a predetermined interval therebetween in the circumferential direction and being respectively provided with a primary coil and a secondary coil wound thereon, said stator being fixed on one end of said cylinder in such a manner that said rod is slidably disposed through a space defined by said poles with a predetermined gap being formed between said rod and said poles; projections provided, with a predetermined axial pitch, at least on the surface of said rod opposing each of said poles in such a manner that a predetermined difference is produced among said poles in the corresponding relationship between said projections and end protions of said poles, said rod being made of magnetic substance; a circuit for exciting each of said primary coils with one of reference AC signals which are out of phase with adjacent poles by a predetermined electrical angle; a circuit for summing outputs of said secondary coils and thereby generating an output signal resulting by phase shifting the reference AC signals in accordance with a relative linear position of said rod; and a circuit for detecting a phase difference between a predetermined one of the reference AC signal and the output signal of said summing circuit to obtain detected phase difference data as piston rod position data.

Claim 21

Dependent Claim 72 words

A positioning control device as defined in any of Claims 9 to 17 wherein said velocity detection means uses the piston rod position data detected by said position detection means to operate the velocity from timewise increase or decrease of the value of this position data and said acceleration detection means operates the acceleration from timewise increase or decrease of the value of the velocity data obtained by said velocity detection means.

Claim 22

Dependent Claim 45 words

A positioning control device as defined in any of Claims 10 to 18 which further comprises means for effecting control at the starting of movement of said cylinder so that said brake is released prior to change of a direction control valve for said cylinder.

Claim 23

Dependent Claim 20 words

A positioning control device as defined in any of Claims 10 to 19 wherein said cylinder is a pneumatic cylinder.

Positioning control system for a fluid powered cylinder

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