PiCUS TMSO Manual
17
3.6 Measuring Modes of the System / Typical Applications
3.6.1 Wind Response Measurement (WRM)
The aim of wind response measurement is to measure the root plate inclination of the tree and
to put it in relation to the prevailing wind speed, especially the gusts. Knowledge of the behavior
in the wind allows experts to assess the tree, especially with regard to its stability. More details
for evaluation in the manual of the
TMS.Software
.
The PTMSO directly records the change in the inclination of the tree during a wind event,
similar to the older TMS 3, from which the underlying measurement method originates.
Accordingly, a tilt sensor is attached to each tree to be monitored at ground level (called the
base sensor
), in order to be able to measure the inclination of the root plate directly. As with
the TMS 3, however, the sensors of the PTMSO can also be influenced by external disturbance
variables, which leads to a distortion of the measured values.
To filter these out, an additional sensor is needed as a reference, which is mounted at a height
of 2 - 2.5m (called the
control sensor
).
These two sensor types do not represent different hardware variants, but simply have different
behavior in the system due to the corresponding configuration. This means that each TMSO.IM
can be a base or control sensor.
In addition, the TMSO.CU can also assume the role of a control sensor if required.
In order to distinguish wind-induced inclination events from other movements or disturbances,
an event detection is carried out. This reacts to properties of the inclination measurement data:
An actual inclination event must be visible simultaneously on the readings of the base
AND control sensor and show a comparable waveform
An actual tilt event ALWAYS causes the control sensor to tilt more than the base sensor
To achieve this result, however, it is not absolutely necessary to use both a base and a control
sensor on each individual tree.
For a group of trees standing close together, it can be assumed that during a wind event, all
trees are hit by the same gust of wind almost simultaneously. This means that as soon as only
one of the trees has a control and base sensor, a wind inclination event can be identified on
this reference tree. Since all sensors are synchronized with each other in time, the time stamp
of the reference tree event can be compared with the recordings of the base sensors on the
other trees. If these have registered events at the same time, then these too are real inclination
events induced by the same gust of wind. This allows an event to be detected via criterion 1,
even if criterion 2 fails due to the lack of control sensors on the same tree.
The older TMS 3 continuously recorded the measurement data over the period of use, which
can lead to very large amounts of data, but in the end only a very small proportion of which is
actually relevant for evaluation and interpretation.
In contrast, the PTMSO already pre-filters the raw data and only records the data that are likely
to be relevant. This considerably reduces the amount of data to be transmitted and thus saves
energy and working time of the user during evaluation.
This filtering and selection of the relevant data takes place in two phases.
Phase 1
- takes place directly in the independently operating TMSO.IM:
If the system has been put into the measuring mode by a measuring plan, all TMSO.IM will
start to measure inclination values. They do this for a certain time, which is specified by the
TMSO.CU, the
measurement cycle
.
By default, the length of the measuring cycle is set to 1 hour (see also
