Operating Instructions
NAV350
Product description
8013889/ZML0/2017-06-09
© SICK AG · Germany · All rights reserved · Subject to change without notice
27
Chapter
3
Measurement quality as indicator for the reliability of the position data
Together with the position data, the NAV350 provides the measurement quality to the vehi-
cle computer. The measurement quality evaluates the deviation between the saved reflec-
tor positions and the detected reflector positions. It is a relative measure for the reliability
of the position data. The measurement quality is output in millimetres as the standard de-
viations of all measured values for the reflectors detected per scan.
Errors in the measurement are output via the optional position data.
For further information on quality see document “NAV350 Telegram listing”, part
no.:
8013893.
If large deviations occur between saved and detected reflector positions, it is recommended
to check the reflector placement and the velocity information, as well as to limit the accel-
eration of the AGV if possible.
The measurement quality has an effect on the control loop in the vehicle computer. Using
this information, the system integrator can determine to what extent the position data from
the odometry need to be corrected by the position data from the NAV350. The influence of
the position data from the NAV350 on the correction is application-specific and depends on
the quality of the odometry and the positioning tolerances allowed in the system.
3.7.2
Measuring accuracy
Positions in a restricted action radius of the NAV350 are measured more accurately and im-
prove the positioning accuracy (see
section 9.1 “Data sheet NAV350” on page 63
).
Recommendation
Mount the reflectors at docking stations (e.g. pallet transfer point) and on bends within the
defined, restricted action radius of the NAV350 or in relation to the route.
From the reflectors measured the NAV350 selects the 4 to 8 best distributed reflectors and
uses these reflectors to determine the position.
Fig. 13:
Restricted action radius
r
max
r
min