Error analysis and correction in the installation

2022-09-27
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Error analysis and correction during the installation of the perpendicularity disc

the perpendicularity disc is composed of main grating, indicating grating, indicating grating base, shaft and shaft sleeve. During the installation of the perpendicularity disc, the index difference of the vertical disc and the inclination error of the horizontal axis will occur

the index difference of the vertical plate is caused by the incorrect installation of the fixed indicating grating, which means that when the collimation axis is horizontal, the reading of the perpendicularity plate is not 90 degrees. After installing the perpendicularity pan, place the instrument on the instrument pier, aim at the target at infinity of the collimator roughly the same height as the instrument, and observe the zenith distance of the target with the left and right sides of the pan. Then

left: α= 90°-L+I; Disc right: α= R-270 ° -i

gets i=1/2 (l+r-360 °)

if the index difference I exceeds the specified limit, it will be corrected. There are two kinds of correction: one is mechanical correction, and the other is software correction. Mechanical correction: loosen the four screws connecting the indicating grating base and the support, rotate and adjust the indicating grating base, and measure the index difference again on the left and right sides of the disc until it meets the needs

software correction: start the index difference correction program of the instrument, according to the prompt of the display screen, aim the collimator on the left and right of the disc, extract the index difference and store it. After the above correction, the angle displayed by the instrument is the value after correcting the index difference, that is, the value when the index is in the correct installation position

the tilt error of the horizontal axis is caused by the unequal height of the two supports supporting the horizontal axis. When the horizontal axis is tilted, it will have a great impact on the measurement of the horizontal angle. On the premise that the vertical axis is vertical and the collimation axis is also vertical:

1 With the center O of the horizontal axis as the center of the circle and any length as the radius as the ball, hH1 represents the horizontal position of the horizontal axis and H ′ H1 ′ represents the inclination angle of the horizontal axis, it will reach the position of 93.3 million tons in 2020. The vertical angle is on the H1 side. When the horizontal axis rotates around the vertical axis, the inclination angle in all directions β Is unchanged

2. When the horizontal axis is horizontal, aim at the target T, then the vertical aiming plane is oztm ', which reads M' on the horizontal dial. If the horizontal axis is inclined β Angle. When the collimation axis points to the zenith, the collimation axis will not be in the correct oz position, but will move to the oz 'position. When using this collimation axis to collimate the target T, the collimation plane is the inclined plane oz' TM, and the reading on the horizontal dial is m

chord length mm '= △ β It is the influence of horizontal axis inclination error on direction reading. Make ozm vertical plane, in spherical triangle ZTM, zt=z, lzmt= β, TM≈ α, LTZM=△ β, Then from the formula of spherical vertical angle: sin △ β= Sin β/Sinz*Sin α

because β And △ β It is a small angle, and you can get △ β=β tg α, This is the relationship between the horizontal axis tilt error and the horizontal angle on January 19. Horizontal and low (high) point methods are used to verify the tilt error of the horizontal axis: two points are selected indoors, one is higher than the horizontal line of sight, the other is lower than the horizontal line of sight, and the vertical control mode adopts full digital pulse control angle to meet α High=- α Low,

when observing the high point: (L-R) high =2l/cos α High +2 β* tg α High

when observing a low point: (L-R) low =2l/cos α Low +2 β* tg α Low

cause α Height = ∣ α Low ∣; be β= 1/2 (C high-c low) cot α

when using flat and high reading, as long as (L-R) flat =2c and (L-R) low =2l/cos α Low +2 β* tg α Low

specific operation according to the software prompt, the disc droop and the disc right respectively aim at the horizontal collimator to solve the collimation axis error and indication difference β 1. Turn the left and right collimation point collimators to solve the collimation axis error and index difference β 2. At this time, the horizontal axis inclination error can be obtained according to the above formula

when the inclination error of the horizontal axis is too large, it can be corrected by adjusting the relative position of the indicating grating base on the perpendicularity disk with the support, or it can be compensated according to the software. (end)

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