A multi-turn absolute encoder, an encoding method and a robot are disclosed. The multi-turn absolute encoder includes a rotary shaft, a control circuit board, a magnet, a Hall sensor, a controller, a primary controller, a single-turn absolute encoder and a non-volatile memory. One side of the control circuit board is vertically provided with the rotary shaft. The magnet is connected to the rotary shaft and configured to synchronously rotate about the rotary shaft. The Hall sensor is configured to acquire turn count information of the rotary shaft upon power interruption. The primary controller is configured to calculate an absolute position information of the rotary shaft based on the turn count information of the rotary shaft, a relative position information of the rotary shaft and the absolute position information of the rotary shaft stored in previous power interruption.

A rotary encoder includes: a rotary disk with an angle code; a light source; a detector reading the angle code; and a processing unit acquiring a reading value. The light source includes at least two light-emitting elements spaced from each other. Every time the rotary disk is rotated by a predetermined angle, where an arbitrary angle from a rotation angle within a reading range on the detector is provided as , the processing unit acquires reading values f.sub.I(+) and f.sub.I() with a first light-emitting element and a reading value f.sub.II(+) with a second light-emitting element, to calculate a reading value error due to deflection at an angle + based on the difference between the reading values f.sub.II(+) and f.sub.I(+), to obtain a difference g.sub.I(, ) between the reading values f.sub.I(+) and f.sub.I() such that the error is reflected, and to self-calibrate based on a change in the difference g.sub.I(, ).

A controller (1) to reduce integral non-linearity errors of a magnetic rotary encoder (2) comprises a position error determining unit (20) to determine a plurality of time marks (P0, . . . , Pk) specifying a respective time at which a moving device (3) reaches a respective one of predefined positions (0, . . . , k). The position error determining unit (20) calculates a plurality of error correction parameters (B[0], . . . , B[k]) in dependence on the time marks (P0, . . . , Pk). An error compensation unit (10) of the controller determines a respective error compensated position parameter (.sub.start_comp, 0_comp, . . . , n_comp) for each position parameter (.sub.start, 0, . . . , n) received from the encoder (2) in dependence on the respective position parameter (.sub.start, 0, . . . , n) and the respective error correction parameter (B[0], . . . , B[k]).

A method for detecting a phase on a gear includes obtaining a first determination result indicating whether the gear has been detected at a first detection position. A second determination result indicating whether the gear has been detected at a second detection position is obtained. A third angle between the first and second angles is obtained. A third determination result indicating whether the gear has been detected at a third detection position is obtained. The first angle is replaced with the third angle when the third and first determination results are same, or the second angle is replaced with the third angle when the third and first determination results are different. The phase on the gear is detected based on an angle that is between the first angle and the second angle.

An encoder includes: a reading device that reads respective electric signals from two incremental patterns respectively having graduation array pitches different from each other; a control device that calculates a measurement value, based on the electric signals; and an output device that outputs the measurement value. The control device includes: an absolute position synthesis unit that synthesizes two electric signals to generate a synthesized absolute position; a detection unit that detects two relative positions from the two electric signals; a position calculation unit that performs an arithmetic operation between the relative positions and the synthesized absolute position to calculate a calculated absolute position; an absolute position comparison unit that compares the calculated absolute position with the synthesized absolute position; and a relative position comparison unit that compares the two relative positions with each other. The output device outputs error information, based on a comparison result output from the control device.

An absolute encoder that receives a current from an electronic power supply includes: a plurality of regulators connected in parallel with one another that receive a drive current from an electronic power supply in which a magnitude of a constant voltage output to the absolute encoder and a magnitude of a drive current needed for outputting the constant voltage are different; a voltage detection unit configured to detect an output voltage of at least one regulator of the plurality of regulators; and an abnormality detection unit for detecting an abnormality of a current from an electronic power supply consumed when the absolute encoder is driven based on the output voltage detected by the voltage detection unit.

A method is provided for operating an optical sensor unit comprising markings arranged on a piston rod of a cylinder of a n industrial truck. The method, comprises the steps of: transmitting optical radiation onto markings arranged on the piston rod receiving optical radiation reflected by the markings arranged on the piston rod detecting an oscillating voltage signal by the receiver from the optical radiation reflected by the markings on the piston rod; converting the voltage signal into a binary digital signal; setting a control current applied to the transmitter as a control variable, specifying a target voltage amplitude from the detected oscillating voltage signal as a reference variable, determining an average actual voltage amplitude over a plurality of voltage fluctuations produced by traversal of a plurality of markings from the respective actual voltage amplitudes of the voltage signals, determining a control deviation value between a target voltage amplitude and an average associated with the actual voltage amplitudes of the voltage signals, and correcting the average associated with the actual voltage amplitudes of the voltage signals by changing the control current in dependence of the control deviation value.

To reduce the error in a rotational angle detected by a rotational angle detection apparatus, provided is a rotational angle detection apparatus that detects a rotational angle of a magnetic field generation source, including a magnetic field detection apparatus that detects magnetic field components in at least two directions, and outputs resulting detection data; a correction value calculating section that calculates correction values for correcting an angle error of the rotational angle, based on a steady-state error that does not depend on rotation of the magnetic field generation source; and an angle computing section that calculates the rotational angle of the magnetic field generation source based on the detection data and the correction values, and outputs an angle signal indicating the rotational angle.

A method of correcting a position reading from a position sensing arrangement. The position sensing arrangement is suitable for sensing the position of a revolute joint of an articulated structure, and comprises a disc having a magnetic ring with magnetic pole pairs and a magnetic sensor assembly comprising a magnetic sensor array for detecting the magnetic pole pairs of the magnetic ring. The method comprises: for each pole pair of the magnetic ring, taking a calibration pole pair position reading with the magnetic sensor array, and generating a pole pair correcting function by comparing the calibration pole pair position reading with a model pole pair position reading; averaging the pole pair correcting functions of the pole pairs of the magnetic ring to generate an average pole pair correcting function for the magnetic ring; taking a position reading with the magnetic sensor array, the position reading comprising a plurality of pole pair position readings; and generating a corrected position reading by deducting the average pole pair correcting function from each pole pair position reading.

A position forecasting apparatus for forecasting a position at a predetermined time of a continuously operating moving body is provided with an estimation part that finds an estimated position state of the moving body at a time in the past before the predetermined time and a position forecasting part that forecasts the position of the moving body at the predetermined time based on the estimated position state of the moving body estimated by the estimation part.