Other

Atsutoshi Goto

Amiteq Co., Ltd.

Nobuyuki Akatsu

Kazuya Sakamoto

Hiroshi Sakamoto

Yasuhiro Yuasa

Akio Yamamoto

Shuichi Tanaka

Daisuke Goto

Shuiti Tanaka

A device has a construction capable of promoting miniaturization, and comprises: a coil; a magnetism-responsive member disposed so as to be displaced relative to the coil according to a position of a detection object; and a self-oscillation circuit that incorporates the coil therein as an oscillation element so that an oscillation frequency varies with an inductance variation of the coil responsive to an displacement of the magnetism-responsive member relative to the coil. An arithmetic section generates a measured value responsive to oscillation frequency based on an oscillation output of the self-oscillation circuit, calculates velocity data by differentiating successive measured values, and calculates displacement data by integrating the velocity data. An offset error component caused by the peripheral temperature or a mechanical attachment position of the detection device can be automatically cancelled or reduced by the differential operation for calculating the velocity data, and precise displacement detection can be realized.

Displacement detection device

Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(&#x3c9;t&#xb1;d+&#x3b8;), sin((&#x3c9;t&#xb1;d&#x2212;&#x3b8;)) are electrically synthesized which have electric phase angles (&#x3b8;) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. '&#xb1;d' here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change. In the synthesized two signals, the phase variation errors (&#xb1;d) appear in the same direction, while the phase differences (&#x3b8;) corresponding to the position are shifted in opposite, positive and negative, directions. Thus, by measuring the respective phase shift amounts (&#xb1;d+&#x3b8;, &#xb1;d&#x2212;&#x3b8;) and performing appropriate operation, it is allowed to cancel out or extract the error (&#xb1;d) so that an accurate phase difference (&#x3b8;) can be detected. Position detection data indicative of the detected phase difference (&#x3b8;) is converted into a pulse-width-modulated signal and transmitted in the pulse-width-modulated form.

Phase difference detection device and method for a position detector

The present invention is directed to a position detection method and apparatus whereby a first A.C. output signal having an electric phase angle shifted in a positive direction in accordance with a position-to-be-detected is produced along with a second A.C. output signal having an electric phase angle shifted in a negative direction. First and second detection data are then generated by detecting respective phase differences of the first and second A.C. output signals from a predetermined reference phase. The first and second predicted values are provided on the bases of at least two successive samples of the first and second detection data, respectively. The first and second predicted values are then modified to provide a standard predicted value for correcting any nonlinear error resulting from the Doppler effect. Using this standard predicted value, predictive interpolation is performed on the first and second detection data sequentially with the passage of time to provide first and second interpolated data.

Position detection data generating method and apparatus based on phase shift principle

Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(&ohgr;t&plusmn;d&plus;&thgr;), sin(&ohgr;t&plusmn;d&minus;&thgr;)) are electrically synthesized which have electric phase angles (&thgr;) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. &ldquo;&plusmn;d&rdquo; here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change. In the synthesized two signals, the phase variation errors (&plusmn;d) appear in the same direction, while the phase differences (&thgr;) corresponding to the position are shifted in opposite, positive and negative, directions. Thus, by measuring the respective phase shift amounts (&plusmn;d&plus;&thgr;, &plusmn;d&minus;&thgr;) and performing appropriate operation, it is allowed to cancel out or extract the error (&plusmn;d) so that an accurate phase difference (&thgr;) can be detected. Position detection data indicative of the detected phase difference (&thgr;) is converted into a pulse-width-modulated signal and transmitted in the pulse-width-modulated form.

First A.C. output signal sin(&ohgr;&plus;&thgr;) having an electric phase angle shifted in a positive direction in accordance with a position-to-be-detected is produced along with a second A.C. output signal sin(&ohgr;&minus;&thgr;) having an electric phase angle shifted in a negative direction. First and second detection data are generated by detecting respective phase differences (&plus;&thgr; and &minus;&thgr;) of the first and second A.C. output signals from a predetermined reference phase. First predicted value is provided on the basis of at least two successive samples of the first detection data, and a second predicted value is provided on the basis of at least two successive samples of the second detection data. The first and second predicted values are modified to provide a standard predicted value for correcting a nonlinear error resulting from the Doppler effect. Using this standard predicted value, predictive interpolation is performed on the first and second detection data sequentially with the passage of time, so as to provide first and second interpolated detection data. With this arrangement, it is possible to achieve improved response and detection performance with respect to dynamic characteristics. Error due to a temperature change or the like may be eliminated by performing an arithmetic operation on the first and second interpolated detection data, so that temperature drift characteristics can be improved.

A winding section includes a primary winding to be excited by a single-phase A.C. signal, and a plurality of secondary windings provided at different locations with respect to a predetermined direction of linear movement. A variable magnetic coupling section includes a plurality of magnetic response members provided in repetition at a predetermined pitch along the direction of linear movement, and allows inductive A.C. output signals, amplitude-modulated in accordance with a varying linear position of an object of detection, to be produced in the individual secondary windings with amplitude function characteristics differing depending on positional differences between the secondary windings. Each of the inductive A.C. output signals produced in the secondary windings varies in its amplitude function in periodic cycles each corresponding to the pitch length of the magnetic response members. The variable magnetic coupling section may include a core section made of a wire, and the magnetic response members in the form of metal pieces provided at the predetermined pitch and secured by caulking to the core section.

Induction-type linear position detector device

A group of secondary windings are distributively provided on a stator over a predetermined range, and the respective inductance of the secondary windings in the group is set in such a manner to present predetermined inductance distribution. A rotor has an eccentric shape so as to cause variations in magnetic coupling at individual poles of the stator in response to its current rotational position. By combined use of the magnetic coupling variations between primary and secondary windings on the stator and the predetermined inductance distribution of the secondary windings, high-accuracy detection of a rotational position is achieved with a simple structure. A plurality of primary windings may be set so as to present predetermined inductance distribution.

Induction-type rotational position detecting device

Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(.omega.t .+-.d.+-..theta.), sin(.omega.t.+-.d-.theta.)) are electrically synthesized which have electric phase angles (.theta.) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. '.+-.d' here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change. In the synthesized two signals, the phase variation errors (.+-.d) appear in the same direction, while the phase differences (.theta.) corresponding to the position are shifted in opposite, positive and negative, directions. Thus, by measuring the respective phase shift amounts (.+-.d.+-..theta., .+-.d-.theta.) and performing appropriate operation, it is allowed to cancel out or extract the error (.+-.d) so that an accurate phase difference (.theta.) can be detected.

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Higashiyamato, Japan

Nobuyuki Akatsu