Machine body is not aligned (inaccurate)

Issue

The position of the car body displayed on the tablet does not match the actual position.

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

*The reference for checking the accuracy is Z±5cm (N,E±10cm) compared to the benchmark coordinates.

How to deal

It may be possible to improve the situation by reviewing the following

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

1. Point of change	Points of change before and after the accuracy failure, such as change of operation location, change of correction information, temporary removal of GNSS antenna installation at the time of turnaround, re-calibration, etc.
2. Environment	Satellite acquisition environment (high-voltage power lines, sky coverage), correction information acquisition environment (fixed station settings, baseline distance), etc.
3. Error trends	Height direction does not match, horizontal direction (vertical, horizontal) does not match Not aligned by several centimeters, not aligned by ten centimeters, not aligned by tens of centimeters, not aligned by meters Regular, not regular

Factors that are likely to affect the accuracy of the cutting edge (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 Flex kit properly installed?

5. Is the machine calibration properly set up?

6. Others

Simplified table

Factors	Action
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 sure they are not blocking the antenna. ・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 mount point is not selected. (In case of Ntirp use)	[Influence on accuracy in all directions of horizontal and height (irregular)] ・Set appropriate mounting points
Is the baseline distance too far? (In case of Ntrip/external 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 external 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.
Fixed station is not set up and installed in the proper location. (In case of Ntrip/external 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 (rule)] ・Review the localization data. [Project File] →[Using project file] → [Coordinate System]. *Review whether the horizontal and vertical errors are within the threshold values (Normally, it is 10 to 30mm).
TIN data is not appropriate	[Influence on accuracy in all directions of horizontal and height (rule)] ・Review TIN data.

4. Is the Flex kit properly installed?
IMU sensor is not mounted parallel to the machine body.	The IMU sensor must be installed parallel to the ground plane of the machine body, and the IMU sensor mounting surface must be checked with a level or similar tool before installation.
IMU sensor is installed in the wrong direction.	Install the IMU sensor so that the connector side of the IMU sensor faces left at a right angle to the direction of travel.

5. Is the machine calibration properly set up?

The positional relationship between the machine body and GNSS antenna is not measured correctly.

If the GNSS antenna position and the measurement points in front of and behind the machine body are not measured correctly, the accuracy at each measurement point will not be obtained. Please check the setting values of the machine calibration again to be sure.　　　 [Step 4 of Machine Calibration] 1. Measure the distance of each GNSS antenna to the centerline of the machine and confirm that it is entered.(The value to the left of the center line is +, and the value to the right is -.)                 2. Confirm that the distance to the GNSS antenna to the measurement points in front of and in back of the machine is correctly measured and input. 　          　　 3. When measuring the height to the GNSS antenna, please confirm with the calibrator the position of the crawler track as a reference (lower end).

6. Others
Offset is applied.	[Influence on accuracy in height direction (rule)] ・Cancel the offset of the design surface. [Guidance Settings] → [Target Surface Offset Setting] ・Cancel the offset. [Guidance Settings] →[Position Measurement]
Wrong measurement position	[Influence on horizontal accuracy (rule)] ・Check the actual measurement position (left, right) and the measurement position set on the screen (left, right). [Guidance Settings] →[Position Measurement]
Tablet operation 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 the “Age Of Corrections” of GNSS info (recommended 1 second or less). *Check “Vertical /Horizontal RMS” of GNSS info (recommended 0.02 or less).