Composite type rotary encoder and measurement method thereof

Abstract

The invention discloses a composite type rotary encoder and a measurement method of the composite type rotary encoder. The composite type rotary encoder comprises an optical system, a circular coding ring, a rotating shaft, a data collecting module and a data processing unit. The optical system comprises a plurality of light source modules evenly distributed on the surface of the rotating shaft, the circular coding ring and the rotating shaft are coaxially installed, and a plurality of relative code ways and a plurality of absolute code way sets are sequentially arranged on the circular ring inner side face of the circular coding ring. The distances between photoelectric sensors of the relative code ways are equal, the distances between photoelectric sensors of a plurality of absolute code ways of each absolute code way set are equal, and the distances between the photoelectric sensors of the absolute code way sets are gradually increased according to position relations. The relative code ways and each absolute code way are independently connected with the data collecting module, and the data collecting module is connected with the data processing unit. The composite type rotary encoder and the measurement method of the composite type rotary encoder are capable of avoiding measurement errors caused by radial jumps, high in measurement precision, high in anti-interference capability and anti-pollution capability, high in reliability and capable of being widely applied to the field of measurement of rotating angles.

Description

technical field [0001] The invention relates to the field of rotary encoders, in particular to a composite rotary encoder and a measuring method thereof. Background technique [0002] The motor of an AC servo motor is usually equipped with a photoelectric rotary encoder to measure the rotation angle of the motor. The photoelectric rotary encoder can obtain the rotation angle of the rotor to obtain the motor speed information, and the speed information can be fed back to the relevant speed control unit to accurately control the motor. At the same time, the movement displacement, speed, acceleration and other information of the actuator can be calculated indirectly. The positioning accuracy of the servo motor depends on the resolution of the encoder. Photoelectric rotary encoder is a sensor that converts the mechanical geometric displacement on the output shaft into pulse or digital quantity through photoelectric conversion. It is currently the most widely used sensor in the ...

AI Technical Summary

Problems solved by technology

[0003] Incremental encoders can only provide information about the current position relative to the previous position. After the power is interrupted, the information change of the position must be reset to zero before it can be confirmed. At the moment when the power is turned on again, the incremental encoder The server cannot immediately know the current location of the organization

In addition, the grating code disc of the incremental encoder is a circular grating disc with several rectangular holes equally divided on a circular plate with a certain diameter, and the grating code disc of the absolute encoder is radially arranged on the grating plate. A number of concentric tracks, each track is composed of light-transmitting and opaque fan-shaped areas alternately, both of which use circular grating code discs, because the grating code discs of both are depicted on a circular plane perpendicular to the axis of the motor, and the motor In the process of operation, it is inevitable that a certain radial runout will be generated due to vibration, which may cause a small displacement of the code track of the grating code disc. When the radial displacement caused by vibration reaches a certain amplitude, the reading of the encoder may be Errors that affect the accuracy of the measurement results

[0004] Moreover, the encoder disks of photoelectric rotary encoders are all encoded with gratings, which have high requirements for grating writing technology, such as absolute binary encoder disks, n-bit binary code disks have 2 n different codes, the minimum resolution is θ=360° / 2 n , to improve the resolution of the code disc, the value of n must be increased

However, increasing the value of n will definitely cause great difficulties in the production of code discs.

At the same time, the slight manufacturing error of the binary code disc will lead to the advance or delay of individual code channels, which will cause the error of the output signal

In addition, for the circular grating encoder disk, in order to improve the subdivision accuracy of Moiré fringes, the method of increasing the density of the grating lines or placing more photosensitive elements to achieve a higher subdivision of the signal is currently more common It is to describe 50-100 grating lines in the range of 1mm, but it is impossible to accurately place multiple photosensitive elements under a certain phase difference

In general, in the current technology, due to the limitation of the grating writing technology, the accuracy of the photoelectric rotary encoder is also greatly limited.

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