Inaccuracy of cutting edge

Issue

The cutting edge deviates significantly from the benchmark coordinates when checking the accuracy of the cutting edge.

(The difference from the control point is large in the cutting edge position measurement.)

*The allowable value of the cutting edge accuracy is ±5 cm from the benchmark coordinates.

Answer

The problem may be corrected by reviewing the following contents.

*In identifying the cause of the problem, please review the most likely factors based on the three points of view.

１．Change point	Changes before and after the cutting edge accuracy failure, such as change of bucket, change of operating location, change of correction information, and change of parts.
２. Environment	Satellite acquisition environment (high-voltage power lines, sky coverage), correction information acquisition environment (fixed station settings, baseline distance), etc.
３．Cutting edge trends	・Height direction does not match, vertical or horizontal direction does not match ・Do not match by several centimeters, do not match by a dozen centimeters, do not match by several tens of centimeters ・Regularity, no regularity

Factors that are likely to affect the cutting edge accuracy (see the bottom of this page for details)

1. Is the satellite acquisition environment secured?

2. Are the correction information settings appropriate?

3. Is the design data appropriate?

4. Is the bucket calibration properly set up?

5. Is the machine calibration properly set up?

6. Is the hardware in good condition?

7. Others

Simplified table 　(if there is a link, the details can be found at the linked page)

Cause	How to deal
1. Is the satellite acquisition environment secured?
Is there an unobstructed sky above the GNSS antenna?	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・If there are any devices that block the GNSS antenna, make them out from blocking it. ・Work in areas free of high-voltage power lines, etc. ・Work in a location where the sky above the GNSS antenna is unobstructed by forests, valleys, etc. ＊If the sky coverage of the GNSS antenna is low, the number of satellites acquired may decrease, resulting in inaccuracy of the cutting edge.

2. Are the correction information settings appropriate?
Appropriate mounti points are not selected. (In case of Ntirp use)	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・Set appropriate mount points
Is the baseline distance too far? (In case of Ntrip/radio use)	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・If using Ntrip, work within 10 km of the recommended baseline distance. [GNSS Settings] → [GNSS Info]. ・In case of using a radio, it depends on the specification of the radio. *The farther the distance from the electronic reference station/fixed station, the less stable the accuracy tends to be.
The fixed station is not set up and installed in the proper location. (In case of Ntrip/radio use)	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・Set the appropriate correction information format. ・Review the installation environment of the fixed station (Is there anything obstructing the sky above the antenna?)

3. Is the design data (project file) appropriate?
Localization data is not appropriate	[Influence on accuracy in all directions of horizontal and height (regular) ] ・Review localization data [Project File] → Edit mark→[Coordinate System]. ＊Review whether the horizontal and vertical residuals are within the threshold values (Normally, the threshold value is 10 to 30 mm).
TIN data is not appropriate	[Influence on accuracy in all directions of horizontal and height (regular) ] ・Review TIN data.

４．4. Is the bucket calibration properly set up?
Selected bucket file is not appropriate (different from actual bucket)	[Influence on accuracy in all directions of horizontal and height (regular) ] ・Check if the bucket actually installed is selected in the bucket file. [Bucket Configuration]→［Bucket File Settings］
Input value of bucket settings is not measured correctly. (Bucket Tooth Set Calibration screen)	[Influence on accuracy in all directions of horizontal and height (regular) ] ・Review the angle of [a] in the bucket calibration value. ・Set [F] if the cutting edge is worn out since the bucket calibration. ・Review the length of [A] and [C] of the bucket calibration value. [Bucket Configuration]→[Select any bucket]
	[Influence on horizontal accuracy(regular) ] ・Review [D (bucket width)] of the bucket calibration value.

5. Is the machine calibration properly set up?
Machine calibration is not measured correctly.	[Influence on accuracy in all directions of horizontal and height (regular) ] ・If not calibrated on flat and firm ground, re-measure. ・Review GNSS antenna measurements (STEP8). [Machine Calibration Settings]→[Machine Calibration(STEP8)]
	[Influence on horizontal accuracy (regular) ] ・Enter the pole height for the machine calibration (STEP10) and do not enter the prism height for the total station (do not double enter). [Machine Calibration Settings]→[Machine Calibration(STEP10)]
GNSS antenna is not properly fixed	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・Review whether the GNSS antenna fixing bracket is loosing.
Coupler (A-lock, B-lock) is installed and the measurement point is wrong.	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・When installing a coupler, calibrate the machine with the coupler installed.

6. Is the hardware in good condition?
IMU sensor is malfunctioning.	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・If the accuracy of IMU sensor (body, boom, arm, bucket) is out of threshold value, replace it.

7. Others
Offset is applied. (Offset in design surface)	[Influence on accuracy in height direction(regular) ] ・Cancel the offset of the design surface. [Guidance Settings]→[Target Surface Settings] ・Cancel the matching of cutting edge coordinates. [Guidance Settings]→[Accuracy check]
Wrong cutting edge measurement position.	[Influence on horizontal accuracy (regular) ] ・Check the actual measured cutting edge position (left, middle, right) and set them the cutting edge position on the screen (left, middle, right). [Guidance Settings]→[Accuracy check]
The motion of tablet is slow.	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・Lighten the storage capacity. ・TIN data (design data) should be lightened.
Communication of correction information is not stable.	[Influence on accuracy in all directions of horizontal and height (irregular) ] ・Ensure stable wireless communication environment. ・Ensure stable communication environment of mobile communication network. [GNSS Settings]→[GNSS Info] ＊Check [Age Of Corrections] of GNSS info.(Recommendation: 1 second or less) ＊Check [Vertical RMS/Horizontal RMS] of GNSS info(recommended 0.02 or less).