Report STSM L-F Pau

Cost Action: TU1302
Action Title: Satellite Positioning Performance
Assessment for Road Transport -SaPPART
Short Term Scientific Mission
STSM Report, for STSM July 08-15, 2015 to University of Forestry,
Krakow (Poland)
Submitted to:
Cost SaPPART STSM Steering Committee
Submitted 2015-07-25 by:
L-F Pau, Professor
CBS, Denmark
OBJECTIVES
The main objective of the STSM was to interact around implications of GNSS inaccuracies in forestry
exploitation, and to carry out extensive experimental data collection in three forest areas in Southern
Poland, in view of building a model of these implications. The context is the progressive introduction
of “precision harvesting” in forestry, and of the design of assisted or robotic forestry harvesting
machinery. The measurements were made with equipment from the Danish guest institution as well as
the Polish host institution, and involved a total of 7 research staff or forest management civil servants.
In addition, the STSM researcher presented the SaPPART Action and the STSM to staff from three
Faculties of the University of Agriculture, Krakow and to the Polish Forest Management Authority.
WORK SCHEDULE
Duration
1 week
Dates
08 July-15 July , 2015 (earlier dates had been
arranged but could not be carried out for lack of
COST notification)
Host Institute
Faculty of Forestry, University of Agriculture,
Krakow (Poland)
Home Institute
CBS, Copenhagen (Denmark ) (plus other
assignments e.g. ETSI and RSM)
WORK DESCRIPTION
-Day 1 was devoted to presentation and discussions about the model, the design of which had been
initiated months ago after the notification of the STSM; the afternoon was devoted to training Krakow
scientists on the data collection protocol and use of measurement instruments; this was carried out on a
high rise roof of a university building.
-Day 2 was devoted to field measurements at two sites in exploitation distant about 150 km from
Krakow, chosen because of the availability of high precision geodetic reference coordinates ; the first
site (A) was a on a sloped terrain with obtrusive high density spruce canopy ; the second site (B) was
on a rather flat mountain top with medium sized sparse pine. The Forest Management Authority
assigned two officers to assist and transported the 6 researchers on long distances to the sites.
-Day 3 was devoted to data collation and verification ,and continuous model development.
-Day 4 was devoted to field measurements at a third site ( C ) in exploitation about 80 km from
Krakow, with also a high precision geodetic reference point. In line with research needs, the weather
conditions were rainy, and the terrain was mostly flat with elements of plantation rows, and populated
mostly by pine.
-Day 5 was devoted to seminar presentation to three faculties of the University of Agriculture
(Department of Forest Engineering, Department of Forest Work Mechanisation and Department of
Forest and Wood Utilization), as well as data collation and verification.:
http://wl.ur.krakow.pl/index/site/962
The model specification got further refined based on the field work, as such type of models are
available nowhere.
The equipment used included: theodolite, laser range finders, one professional GNSS receiver, two low
cost GPS receivers, altimeters, altimeter equipment using the wireless networks, scales, cameras for
digital image acquisition, and miscellaneous equipment and poles to mark the measurement points on a
radial grid around the geodetic reference points. The data collection required 4-6 persons.
MAIN RESULTS
Whereas aircraft, boat and car navigation often rely on high accuracy global satellite positioning
systems (GNSS), it is only recently that their relevance has been put in the context of agriculture,
vineyards, farming and forestry. It is seldom realized by the transport industry that agricultural, forestry
and civil engineering industries utilize worldwide a number of vehicles about equivalent to one third of
cars. These fields are however not behind in the adoption of high tech , with especially robots,
“precision farming”, and the use of drones. In “precision farming”, mapping information is matched
with GNSS measurements and vision/sensor systems to image plants/ crops, and accurately navigate
between them to perform specific tasks, besides adding to the traceability or quality control of
harvested products.
In agriculture and forestry, inaccuracies in position and directional information lead directly to
economic, productivity and environmental losses. Crop parcel zones may not be harvested. Crop
collection after a navigation error requires a “second pass” which costs manpower time, machine time
and fuel. Residues may be generated at higher rates lowering yield and eventually leading to
environmental problems over some time. Nevertheless, such economic impacts of GNSS inaccuracies
are rarely even considered, even if they should as in the overall trade-offs between manpower costs,
equipment usage time, and expensive precision farming equipment.
The STSM focusses on the effects of GNSS inaccuracies effects affecting forestry operations, which
offer a significant challenges as the geographic location of individual points using GNSS receivers
largely requires an unobstructed line of sight from the points to a minimum number of satellites. This
is often difficult to achieve in forest environments, as trunks, branches and leaves can block the GNSS
signals. The specific concern addressed is that of of GNSS assisted or GPNSS robotic guided forest
harvesting. In future generation harvesters, but already now in some instances, the harvester has its
own integrated GNSS receiver, coupled to a data acquisition and to a communications module.
In a robotic operational mode, the harvester makes autonomously navigation decisions to maximize
productivity and harvesting revenue. The forest product industry should maximize the combined value
and quality of timber logs, and secondary products, while minimizing the volume and handling of
residues. So, in many ways, the economic impact of enhanced inventory information and yard
operations starts right at the robotic or assisted harvesting machinery.
It was found during the STSM that the key differences with the analysis of GNSS accuracy for road
transport are:
I.
a key priority given to 3-D location and directional accuracy (as opposed to 2-D location an
speed accuracy as in cars), dictated by harvester cutting blade geometry & dynamics, e.g. 2-D scatter
plots of GNSS fixes are not sufficient and Kalman models cannot handle errors due to vegetation
II.
the lack of a-priori 3-D spatial information of occluding volumes;
III.
the economic impact on harvesting yield across surfaces;
IV.
safety implications of collision avoidance with the surroundings, as opposed to between
vehicles.
The research questions which have been investigated experimentally and by modeling are:
A. how much are location and directional accuracies of GNSS signal degraded in forest, compared to
the operational requirements of future semi-automated precision forestry harvesting?
B. how approximately is the harvesting yield affected by GNSS signal accuracy in forestry
environments, so a trade-off can be made between harvesting by manned resources vs. costlier semiautonomous equipment.
The methodology chosen was to measure GNSS inaccuracies “in situ” in different types of forest on
radial grids (min. 8 different directions) around the location of a tree to be harvested by a robotic
harvesting machine; the exact location of the tree was known from geodetic reference data. The forest
type diffferences which could be characterized experimentally were: tree heights, species, terrain slope,
and rain/humidity levels. The 3-dimensional distance errors to cutting points on trees have been
determined, as well as the directional cutting inaccuracies, if they were derived from GNSS signals.
Combined with a directional volumetric tree trunk and canopy model, the data collected allow to
estimate the yield (m3 harvested ) and productivity effects (minimizing harvester displacements) of
GNSS errors on precision forestry equipment.
The modelling itself involves a rarely encountered combination of polar, cartesian, UTM and geodetic
coordinate systems, and of the stages in the precision harvesting mechanical dynamics. In a counterintuitive way, as the robotic harvester works around the tree from different directions, the 2-D
positional erors tend to even out , while sometimes significant GNSS z-measurement errors lead to
trunks not cut optimally.
Post-STSM the full model calculations for Forest A were carried out, leading , as examples of results
for a fully robotic harvester, to the following important “worst case” one-pass performances:
Harvester moves from GNSS coordinates only : 2 (no second passes)
Average 3-D range GNSS error for robotic cutting head, m: 17,059 m
Average GNSS z-error,m : 8,172 m
Average GNSS heading error, degrees: 31,3 degrees
Average (low price) canopy yield in m3, per tree : 88,62 m3 (loss 225,53 m3)
Average (high price) spruce trunk yield in m3, per tree: 11,08 m3 (loss 11,53 m3)
Forest B and C measurements and the model are expected to produce significantly better performances.
Multiple passes by harvester are bound to eliminate error implications while GNSS real-time
measurements still accruing significantly to forestry productivity .
COST ACTION PRESENTATION OUTCOME
It was apparent to the audience that novel multidisciplinary research could be carried out under the
COST scheme , with operational and industrial implications. The discussion with staff from the Forest
Administration and Forest Department, showed that the GNSS techniques are not much used yet in
forestry. The reason is the lack of clear guidelines as to the accuracy. There is a great need for
cooperation in this field.
This STSM was an opportunity to expand knowledge about COST Actions , and SaPPART in
particular.
FUTURE RESARCH COLLABORATION
The two institutions are currently heavily involved in model calculations for Forest locations B, C and
will then beable to assess the impacts of species, terrain, humidity . Subsequent analysis will involve
machinery suppliers so they can benefit from the results, and assess which other measurements than
GNSS and mechanical embedded into the harvesters can give them expected benefits from precision
harvesting.
A draft scientific article in a journal with impact factor above 3 is already prepared and will be updated
as the analysis progresses based on the measurements carried out during the STSM.
Both host and guest institutions have enjoyed this truly multidisciplinary research, which already now
opens new horizons .
Another field of collaboration was initiated pertaining to water retention in tree canopies and biomass
in general, which is highly relevant also to better understand and model radio signal and GNSS signal
degradations.
ACKNOWLEDGMENTS
First, is warmly thanked the STSM host, Dr Anna Klamerus Iwan , from the Faculty of Forestry,
University of Agriculture, Krakow, for an excellent interaction and for having organized all the details
of the field trips, seminar, scientific exchanges.
Are greatly thanked Mr Marian Knapek and Wojciech Motyka from Lasy Panstwowe (Polish Forest
Administration) from the Wegierska Gorka forest district for providing access to their forests, and
geodetic information, and performing transportation of a team of six.
Likewise, is greatly thanked the Faculty of Forestry, University of Agriculture, Krakow for making
available a team of field assistants (Mariusz Kormanek, Janusz Gołąb, Krzysztof Owsiak), lending
extensive equipment (Department of Forest Engineering, Jarosław Kucza).
Fot. Forestry Staff (vice Head Officer Forest District Węgierska Górka Wojciech Motyka, PhD Kormanek M., PhD
Owsiak K., PhD Gołąb J., Prof. L-F. Pau, PhD Klamerus-Iwan A., Head Officer Forest District Węgierska Górka
Marian Knapek ., Prof. Gil Waldemar. )
Fot. Owsiak K.
Fot. Klamerus-Iwan (Head Office Forestry Department Węgierska Górka )
http://www.wegierska-gorka.katowice.lasy.gov.pl/
Fot. A.K-I (Forest District Węgierska Górka )
Localization of Forest District Niepołomice
Fot. A.Klamerus-Iwan (Forest District Niepołomice) http://www.niepolomice.krakow.lasy.gov.pl/
Fot. A. Klamerus-Iwan ( Forest District Węgierska Górka)
Localization of Forestry District Węgierska Górka
Fot. A. Klamerus-Iwan (University of Agriculture in Krakow) http://wl.ur.krakow.pl/index/site/960
Fot. K.Owsiak ( University of Agriculture in Krakow)
working group --Calibration and tutorial of the use of GNNS instruments ---- the roof of the
Department of Forestry in Kraków
Fot. M. Kormanek (Skrzyczne Mount) https://en.wikipedia.org/wiki/Skrzyczne
Fot. Gołąb J. (Skrzyczne Mount)