Deformation Analysis of Tripods under Static and Dynamic Loads

Deformation Analysis of Tripods under Static and Dynamic Loads
Deformation Analysis of Tripods under Static and Dynamic Loads
Andreas EICHHORN, Germany
Johannes FABIANKOWITSCH and Daniel NINDL, Austria
Key words: Engineering survey, tripod, deformations, static and dynamic loads
SUMMARY
The deformation of tripods may significantly affect high precision measurements. Therefore it
is necessary to have profound knowledge about the effect of static and dynamic loads
(magnitude and temporal progress). This may be e.g. vertical deformations or torsions
induced by mounting a tacheometer and executing automatic measurement processes. The
effects are dependent on the stability of these ‘accessories’, which often are provided in a
wide bandwith by the manufacturer, starting from a lowcost tripod up to a highend tripod for
industrial measurements.
This study investigates the effect of static and dynamic loads on different types of tripods and
shortly outlines the reasonable application in relation to different measurement tasks and
accuracy requirements. The work is a cooperation between TU Vienna and Leica Geosystems
AG. For a priori theoretical simulations a Finite Element model of a tripod is created to design
the experimental investigations. Because of the complexity of the mechanical system, the
model is firstly restricted to the simulation of vertical static loadings.
For the investigations of height stability, different sensors are evaluated. Considering
measuring accuracy and capability for automatisation, it is decided to use a Leica DNA03
(digital level) to measure the vertical deformations. The determination of torsional effects and
horizontal drift is performed by an electronic collimator from Leica with a sampling rate of 16
Hz. This sampling rate also enables the detection of dynamic effects as a result of tacheometer
movements. The measurements are applied to autocollimation mirrors, mounted on the
tripods. It is shown that the tripod deformations are not negligible if high precision results are
required.
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
1/13
Deformation Analysis of Tripods under Static and Dynamic Loads
Andreas EICHHORN, Germany
Johannes FABIANKOWITSCH and Daniel NINDL, Austria
1. INTRODUCTION
Monitoring of deformation processes and control measurements in industry demand highest
requirements for the stability of the tacheometer adaptation. In many cases, no fixed pillars or
consoles are available and the sensor has to be mounted on a tripod. In this case, the temporal
stability of the tripod is an essential precondition to obtain accurate measuring results.
Accurate means the minimization of random and systematic errors that are induced by
possible movements of the tripod head. In this context, tripod stability means as well height
stability (∆z) as horizontal stability (∆x, ∆y) and must be referred to the whole length of the
measurement process. Of course, the above statements are not only valid for mounted
tacheometers but also for precise levelling instruments (esp. ∆z) or GPS antennas.
Besides external disturbances like wind, sun, humidity, instability of the soil and soil
vibrations, the system tripod Ù tacheometer is also affected by the tacheometer itself. A
modern robot tacheometer widely automatically performs the measurement process by motordriven tacheometer axes. The tacheometer mass (e.g. 5.5 kg, Leica TCRP1201) and its
accelerations (up to rotational speeds with 128 gon/s, Trimble S8) respectively decelerations
induce static and dynamic loads on the tripod which may lead to elastic or (in the worst case)
to plastic deformations. Consequently, the sensor design of a measurement process must not
be restricted to the tacheometer properties but also includes the knowledge about the
interaction between tacheometer and tripod.
In the last years, some investigations of tripod deformations have been carried out (e.g.
Ingensand, 2001 and Depenthal, 2004). As reaction to the increasing numbers of different
tripod types available on the market, a cooperation between TU Vienna and Leica
Geosystems AG was established to investigate and evaluate the properties of different Leica
tripods and competitive products in combination with standard robot tacheometers and test
procedures. One focus is set on the introduction of new materials like fibreglass in tripod
manufacturing (e.g. S40 from Nanjing Survey or Trimax from Crain Inc.). The investigations
are primarily concentrated on static vertical loads and the height stability of the tripod head
respectively quasi-static drift reactions. In addition, the applied methods of deformation
monitoring also enable the detection of dynamic deformation processes in a low frequency
range up to 8 Hz. The following presented results are obtained within the framework of a
diploma thesis (see Nindl, 2006).
2. THEORETICAL SIMULATIONS
In a first step theoretical simulations for tripod stability are performed to find out the range of
static vertical deformations to be expected and to make a decision for a suitable monitoring
system which is able to detect these quantities. The software RSTAB (see Dlubal, 2009) is
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
2/13
used to create a simple Finite Element model (FE-model) of the tripod. The FE-model
abstracts each tripod leg as a system of three homogenous and isotropic parts (upper part with
two beams, overlap and lower part with one beam) with rigid connection. The three legs are
connected in a single knot which represents the tripod head. The tripod itself is fix supported
by the non-elastic ground (see Figure 1a). One main neglect is given by the missing clamps at
the tripod legs. Consequently, the model can only give a rough first impression of the
deformations.
(a)
(b)
Figure 1: FE-model of a tripod created with RSTAB
The geometrical parameters (e.g. leg length and cross section) are derived from a Leica GST
120-9 tripod, which is classified as ‘heavy tripod’ and normally tested with loads up to 30 kg.
The Young’s modulus E is derived from dry hardwood.
The tripod head is loaded with a typical test mass of 30 kg which complies with a vertical
acting force of ca. 300 N (see Figure 1b). As a static reaction the tripod head (knot) performs
a vertical displacement of ∆z = 0.02 mm. By comparison with empirical data obtained in
Section 3 (∆zmeas ≈ 0.02 – 0.03 mm), the FE-model calculations can be proofed and the model
be assumed as realistic. The calculation of the failure load results in ca. 240 kg.
The calculation results give a good first impression about the quantity of static deformations
and are used in Section 3 to design a suitable monitoring system.
3. TRIPOD DEFORMATIONS UNDER STATIC LOADS
3.1 Application of vertical static loads
All following investigations are realized in a lab at Leica Geosystems AG in Heerbrugg /
Switzerland. The lab allows to establish constant environmental conditions by minimization
of changes in temperature and humidity. Other possible external disturbances like soil movements can be excluded. For the application of static vertical loads, a special experimental
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
3/13
setup is created which consists of a cable pull system with test weight for controlled loading
and a digital precise levelling instrument (Leica DNA03) to monitor the vertical tripod
deformations (see Figure 2).
Steel Cable
Test Weight
Levelling-rod
GWLC60
DNA03
Swivel
Tripod
Counterbalance
Pillar
Figure 2: Experimental setup for the investigation of static vertical tripod deformations
Counterbalance and swivel allow a smooth lowering of the test weights (brass-barrels which
simulate the different loads) on the tripod. The resulting vertical deformations are indicated
by the vertical displacements of a short precise levelling-rod (Leica GWLC60) which is fixed
at the main screw of the tripod head (see Figure 3). The levelling instrument DNA03 is
specified with a mean km-error of σ∆h = 0.3 mm. Preliminary investigations show that
repetition measurements with positive correlations on a small cutout of the levelling-rod
achieve accuracys with sdh < 0.01 mm for small height changes. This accuracy requires the
decay of possible compensator oscillations of the DNA03 and restricts the measuring
frequency to max. 0.25 Hz. The measurements are automatically logged and transferred to a
PC. To create reproducible test conditions, the tripod legs are fully extended and equally
spaced on the ground with 1 m distance. The clamps are reproducible tightened with a torque
spanner.
Figure 3: Adaptation of the precise levelling-rod GWLC60 and DNA03
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
4/13
3.2 Investigation results for different types of tripods
The applied static loads vary between 10 kg for light tripods (classification ‘L’) and 30 kg for
heavy tripods (classification ‘H’) and are conform with the typical test procedures at Leica
Geosystems AG. According to ISO12858 (1999), the maximum admissible vertical deformation for tripods is ∆zmax = 0.05 mm. This boundary represents one basic requirement for the
inner stability of the tripod system. The investigated tripods are
−
GST120-9 (H): Leica, wood (beech)
−
S40 (H): Nanjing Survey, fibreglass
−
Trimax (H): Crain Inc., fibreglass
−
CTP101 (H/L): Leica, wood
−
GST05 (L): Leica, wood (pine)
−
GST05L (L): Leica, aluminum
−
CTP103 (L): Leica, aluminum
Deformation ∆z [0.01 mm]
In Figures 4 and 5 two typical time series for vertical deformation processes are shown. Both
are for heavy tripods (wooden tripod Leica GST120-9 and fibreglass tripod Crain Trimax)
with a vertical loading of 30 kg. The measuring frequency is 0.25 Hz (∆t = 4 s).
N o. of m easurem ents ∆ t = 4 s
Figure 4: Wooden tripod Leica GST120-9 loaded with 30 kg
The measurement process starts monitoring the non-loaded tripod (110 measurements
≈ 7 min). After this the load is (slowly) applied to the tripod head and remains there for ca.
20 min. This is a typical value specified by experts for the expected period of possible height
changes. After this, the tripod is unloaded again and monitored for further 6-7 min. The peaks
are induced by the DNA03 itself which has a maximum resolution of 0.01 mm.
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
5/13
Deformation ∆z [0.01 mm]
After loading, the head of the wooden GST120-9 quickly performs a vertical movement of
∆z ≈ 0.03 mm (see Figure 4) and remains in a new balanced state. The increasing number of
peaks from measurement 250 to 400 could be an indicator for a very small overlaid trend.
After unloading, the tripod quickly relaxes but keeps a hysteresis between ∆z = 0.01-0.02 mm
which could be induced by the tripod clamp. In total, it can be stated that the deformation
remains in the admissible range.
N o. of m easurem ents ∆ t = 4 s
Figure 5: Fibreglass tripod Crain Trimax loaded with 30 kg
In comparison with the GST120-9, the head of the fibreglass Trimax performs a significant
larger vertical movement with ∆z ≈ 0.05 mm (see Figure 5), which is barely admissible. The
hysteresis is between ∆z = 0.02-0.03 mm. This shows clearly that concerning mechanical
loads, the construction of the fibreglass tripod is less stable than the wooden one. This
statement must be referred to the whole tripod system, this means properties of the monolithic
parts and connections (e.g. clamps). With the existing experimental design, a separation is not
possible. The results from all tripod investigations are presented in Table 1.
Table 1: Investigation results for height stability (H = heavy tripod ; L = light tripod)
Tripod
Company
Material
Test load
[kg]
Vert. def. ∆z
[0.01 mm]
Boundary
ISO12858
[0.05 mm]
Hysteresis
[0.01 mm]
GST120-9 (H)
Leica
Wood (beech)
30
3
OK
1.5
S40 (H)
Nanjing Survey
Fibreglass
30
4
OK
-2
Trimax (H)
Crain Inc.
Fibreglass
30
5
OK
3
CTP101 (H/L)
Leica
Wood
30
3
OK
1
GST05 (L)
Leica
Wood (pine)
10
1.5
OK
0
GST05L (L)
Leica
Aluminum
10
3
OK
1
CTP103 (L)
Leica
Aluminum
10
2
OK
0.5
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
6/13
In the table it is shown that all tripods fulfill the ISO requirements for vertical height stability.
As mentioned before, the fibreglass tripods in the H-classification obtain somewhat worse
results than wood. After loading, all tripods show no significant vertical drift and remain in a
nearly balanced state. Hysteresis after unloading is restricted to max. 0.03 mm.
Referring to a measurement process, the investigated vertical deformation properties of the
tripods can be evaluated as acceptable, even for high precision requirements. The applied
experimental loads are significantly higher than normal tacheometer loads and the detected
deformations nevertheless in a range of only some hundredth mm. The quick movement to a
nearly balanced state creates a stable position (better than 0.01 mm) of the tripod head during
the actual execution of the measurements. The influence of the hysteresis is only relevant if
the instrument is demounted and remounted again during the progress of the measurements
(using the tripod in the sense of a forced centering). But it must be emphasized that these
statements are only valid for a pure static vertical loading and the absence of external disturbances (e.g. soil vibrations).
3.3 Investigation of quasi-static tripod deformations
Regarding high precision measurement processes, a more critical influence is represented by a
possible horizontal torsion of the tripod head. The torsion directly influences the orientation
of a tacheometer and induces random and systematic errors in the measured horizontal
directions. It can be divided in a long-term quasi-static drift (‘horizontal drift’) and short-term
effects, which are created by the tacheometer movement (torsional rigidity under dynamic
loading, see Section 4).
One main reason for the horizontal drift is the continous decomposition of stresses in the
tripod as a result of tripod setup (e.g. disparate clamping) and tacheometer mounting. To
investigate this effect, a new monitoring system is used which consists of a Leica
autocollimator and a autocollimation mirror (see Figure 6).
Figure 6: Leica autocollimator and mirror for the detection of small tripod rotations
The mirror is fixed at the tripod head and performs the same movement. The autocollimator is
fully automated and has a maximum measuring frequency of 16 Hz. The integrated PSD
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
7/13
(= Position Sensitive Device) enables the detection of the mirror rotations with an expected
accuracy σθ < 2cc.
(b)
Drift [cc]
Drift [cc]
(a)
Time [s]
Time [s]
Figure 7: Monitored horizontal drift of (a) GST120-9 and (b) S40 (only cutout)
For the drift investigations, all selected heavy and light tripods (see Section 3.2 and Table 2)
are loaded with the same tacheometer Leica TCA2003 (weight ≈ 8 kg). This is a typical
instrument for precise engineering survey. During the monitoring process, the tacheometer is
not moving and the load is static. Two representative examples of horizontal drift behaviour
are shown in Figure 7. The total observation time is between 2 and 5 hours. The wooden
tripod GST120-9 (H) shows a convergent behaviour with a total drift of Θ ≈ 6.5cc after 4.5
hours. For many applications, the drift within the first 15 minutes is also a relevant quantity.
With Θ15 ≈ 1.5cc, it is within the range of the measuring accuracy of the TCA2003 (σr = 1.5cc).
According to the specified admissible boundary of Θmax = 8cc, the total drift can also be
evaluated as noncritical. In comparison with the GST120-9, the fibreglass tripod S40 shows a
significant higher torsion. After 15 minutes, the drift is Θ15 ≈ 7cc and after 5 hours, the total
drift converges to Θ ≈ 22.5cc. According to measuring accuracy and admissible boundary,
these quantities must be considered in the design of the measurement process.
Table 2: Results of horizontal drift investigation
Tripod
Company
Material
Total drift
[cc]
Drift after
15min [cc]
Boundary
[8cc]
GST120-9 (H)
Leica
Wood (beech)
6.5
1.5
OK
S40 (H)
Nanjing Survey
Fibreglass
22.5
7
NO
Trimax (H)
Crain Inc.
Fibreglass
9
8
NO
CTP101 (H/L)
Leica
Wood
4
1.5
OK
GST05 (L)
Leica
Wood (pine)
3
0.5
OK
GST05L (L)
Leica
Aluminum
23
15
NO
CTP103 (L)
Leica
Aluminum
9.5
2
NO
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
8/13
The results of all investigated tripods are shown in Table 2. It is obvious that in comparison
with fibreglass and aluminun, wood shows the best drift properties.
4. TRIPOD DEFORMATIONS UNDER DYNAMIC LOADS
4.1 Application of dynamic loads
The effect of dynamic loads (e.g. torques induced by tacheometer accelerations and decelerations) is also an important target goal for the investigation of tripod deformations. In the
following, the combination of autocollimator and autocollimation mirror (see Figure 6) is
again used for monitoring. It must be emphasized that the restricted measuring frequency of
the autocollimator (16 Hz) is not really suitable for dynamic processes like vibrations.
Nevertheless, some first results can be obtained and will be discussed in the following section.
Loaded by a rotating tacheometer, the horizontal torsional rigidity is an important criterion for
the evaluation of tripod stability. It describes the resistance of the tripod against horizontal
torsions induced by torques (in particular torsional moments, e.g. Böge, 2006). It mainly
depends on geometry (e.g. cross sections) and material (Young’s and shear moduli) of the
tripod components. Typical Leica tacheometers (e.g. TCA2003) achieve rotational speeds up
to 50 gon/s. Within the acceleration and deceleration phases they create horizontal torques up
to MT = 56 Ncm. The magnitudes of the torques are restricted by a friction clutch.
The interesting question is now, if the torsional rigidity of a tripod is able to compensate
tacheometer movements or not. If not, the resulting horizontal torsion of the tripod head may
influence the orientation of the tacheometer and creates random and systematic errors (see
also Section 3.3).
4.2 Investigation of dynamic tripod deformations
The experimental setup again consists of different types of tripods (see Section 3.2 and
Table 3) with a mounted tacheometer TCA2003. In comparison to Section 3.3, the
tacheometer is now moving. It performs an automatic set measurement to two diametrically
arranged prisms P1 and P2. The prisms are measured in the sequence:
P1 in face 1 (P1’) => face 2 (P1’’) => P2 in face 2 (P2’’) => face 1 (P2’)
In Figure 8 the monitoring results of the horizontal torsion are presented for the wooden
tripod GST120-9. The different peaks (maximum amplitudes of horizontal torsion) clearly
indicate the different tacheometer actions:
−
Single peaks are created by manual actions on the tacheometer keyboard (e.g. start of
set measurement) or accelerations (negative peak) respectively decelerations (positive
peak) in the tacheometer rotation.
−
Double peaks are created as reaction to the beginning of a change of face (chof) of the
tacheometer.
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
9/13
All peaks show a similar magnitude between ∆θ ≈ ± (3-5cc). With the current monitoring
design, a significant influence on the accuracy of horizontal directions cannot be detected as
normally the measurement process shortly starts after the peak event. For more detailed investigations, a higher temporal resolution and a better correlation between torsions and horizontal
circle readings are required. Taking into account the accuracy of the autocollimator (see
Section 3.3), the variations between the peaks are not significant.
Measurem ent
Turn
Chof
Horizontal torsion [cc]
Measurem ent
Turn
Measurem ent
Turn
Chof
Measurem ent
Start
set m easurem ent
Chof = Change of face
Tim e [s]
Figure 8: Horizontal torsion of tripod GST120-9 during dynamic loading with TCA2003
Horizontal torsion [cc]
Figure 9 shows the comparison between two different tripod materials: GST120-9 (wood) and
Trimax (fibreglass). Both tripods are loaded with the TCA2003 which performs an automatic
set measurement. It is obvious that the fibreglass tripod gets larger peaks (up to ∆θ ≈ 15cc)
than the wooden tripod (∆θ ≤ 10cc). The main reason for this are the good damping properties
of wood in comparison to the refractory fibreglass.
Tim e [s]
Figure 9: Comparison of torsion: wooden tripod (GST120-9) and fibreglass tripod (Trimax)
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
10/13
The mean peak-values for all investigated tripods are shown in Table 3. To get comparable
results, the experimental setup is the same for all different types.
Table 3: Mean peaks as reaction to TCA2003 movements (+ clockwise ; - counterclockwise)
Tripod
Company
Material
∆Θmean (+)
∆Θmean (-)
[cc]
[cc]
GST120-9 (H)
Leica
Wood (beech)
6
-6
S40 (H)
Nanjing Survey
Fibreglass
6
-6
Trimax (H)
Crain Inc.
Fibreglass
9
-8
CTP101 (H/L)
Leica
Wood
6
-5
GST05 (L)
Leica
Wood (pine)
17
-18
GST05L (L)
Leica
Aluminum
15
-15
CTP103 (L)
Leica
Aluminum
7
-8
As a first rough result it can be stated that the light tripods generally perform larger torsions
than heavy tripods (except CTP103). This effect seems to be independent of the material and
is obviously correlated with the pure mass distribution in the system tripod Ù tacheometer.
Within a tripod class (H or L) the mean values show no significant differentiation (except
again CTP103). But as shown in Figure 9, extreme values may have significant differences
dependent on the tripod material.
5. CONCLUSIONS AND OUTLOOK
The experimental setups for the investigation of static and quasi-static tripod deformations
can be evaluated as suitable and obtain significant results. All results and discussions are
related to the system tripod Ù tacheometer and neglect possible external disturbances like
soil vibrations, sun, etc.
The height stability of all tested tripods fulfills the ISO requirements and enables the
application in standard and precise measurement processes. No significant vertical drift can be
detected. Possible hysteresis effects should be considered in the case of demounting and
remounting of a tacheometer (forced centering scenario).
Horizontal drift effects must be considered as well in standard as in high precision
measurement processes. In comparison with fibreglass and aluminum, wood shows the best
properties with the lowest movements. Taking into account the specified measuring accuracy
for horizontal directions of typical tacheometers in engineering survey (< 5cc), the drift has a
significant influence and always requires the periodical control of the orientation by stable
reference points. If available, long-term measurement processes should be realized on pillars
or stable wall brackets.
Some first impressions concerning the influence of dynamic effects are obtained. The tripod
reactions to tacheometer actions like accelerations and decelerations can be clearly detected.
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
11/13
But the used monitoring system is not suitable to detect high-frequency deformations. The
experimental setup makes it impossible to separate possible hysteresis effects after the dynamic tripod ‘peak’-reaction from the overlaid drift. This task requires further investigations in
balanced working points (concerning static and quasi-static loadings). A more detailed investigation of the dynamic effects with a self developed laser measurement system and measuring frequencies up to 30 kHz is currently performed in a further diploma thesis (Grubinger,
2009).
REFERENCES
Böge, A. (2006): Technische Mechanik, Vieweg, Wiesbaden
Depenthal, C. (2004): Stativbewegungen bei der Verwendung von Robottachymetern,
Allgemeine Vermessungsnachrichten (AVN), 06/2004, pp. 227–233
Dlubal (2009): Description of the FEM software RSTAB, http://www.dlubal.de, last access
02/2009
Grubinger, A. (2009): Entwicklung eines Laser-Messsystems zur Untersuchung von Vermessungsstativen, Institute of Geodesy and Geophysics, dept. Engineering Geodesy, TU
Vienna, diploma thesis, not published
Ingensand, H. (2001): Systematische Einflüsse auf praktische Messungen mit dem Tachymeter
und Digitalnivellier, in: Qualitätsmanagement in der geodätischen Messtechnik, DVW
Schriftenreihe 42 (2001), pp. 120–137
ISO12858 (1999): ISO12858: Optics and optical Instruments – Ancillary devices for geodetic
instruments – Part 2: Tripods, First Edition, Geneve, 1999
Nindl, D. (2006): Genauigkeitsanalyse von Vermessungsstativen und Dreifüssen unter der
Belastung verschiedener Instrumente, Leica Geosystems AG (dept. TPS) and Institute of
Geodesy and Geophysics, dept. Eng. Geodesy, TU Vienna, diploma thesis, not published
ACKNOWLEDGEMENT
The authors thank the company Leica Geosystems AG (dept. TPS) in Heerbrugg / Switzerland for all support and the possibility to use the technical equipment in the test laboratory.
Our special thank goes to Mirko Wiebking (Leica), the local adviser of Daniel Nindl.
BIOGRAPHICAL NOTES
Prof. Dr. Andreas Eichhorn
Since 2008: Head of the Dept. Geodetic Measurement Systems and Sensor Technology at TU
Darmstadt, Germany
2003-2008: University Assistant at Institute for Geodesy & Geophysics, Engineering Geodesy, Vienna University of Technology, Austria
1996-2002: Research assistant at IAGB, University of Stuttgart, Germany
1990-1996: Studies in Geodesy, University of Karlsruhe, Germany
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
12/13
Dr. Johannes Fabiankowitsch
Since 1996: University Assistant at the Institute of Geodesy and Geophysics, Research group
Engineering Geodesy, Vienna University of Technology
From 1990-1996: Private Industry
From 1980-1990: University Assistant at the Institute of Geodesy and Land Surveying,
Research group Geodesy, Vienna University of Technology
1973-1980: Studies in Geodesy, Vienna University of Technology, Austria
DI Daniel Nindl
2000-2006: Study of Geodesy at Vienna University of Technology
2006-2009: Applications Engineer at Leica Geosystems AG, Heerbrugg, Switzerland
CONTACTS
Prof. Dr.-Ing. Andreas Eichhorn
TU Darmstadt, Geodetic Institute,
Dept. Geodetic Measurement Systems and Sensor Technology
Petersenstr. 13
64287 Darmstadt
GERMANY
Tel. +49 (0)6151 16-2147
Fax + 49 (0)6151 16-4047
Email: eichhorn@geod.tu-darmstadt.de
Web site: http://www.tu-darmstadt.de/fb/bi/geod/index.htm
Dr. Johannes Fabiankowitsch
TU Vienna, Institute for Geodesy and Geophysics, Dept. Engineering Geodesy
Gusshausstr. 27-29
1040 Vienna
AUSTRIA
Tel. +43 (0)1 58801-12841
Fax +43 (0)1 58801-12894
Email: johannes.fabiankowitsch@tuwien.ac.at
Web site: http://info.tuwien.ac.at/ingeo/
DI Daniel Nindl
BA Geomatics, Leica Geosystems AG
Heinrich Wild-Strasse 1
9435 Heerbrugg
SWITZERLAND
Tel. +41 (0)71 727 3442
Fax +41 (0)71 726 5442
Email: Daniel.Nindl@leica-geosystems.com
Web site: http://www.leica-geosystems.com
TS 8C – Instruments and Calibration
Andreas Eichhorn, Johannes Fabiankowitsch and Daniel Nindl
Deformation Analysis of Tripods under Static and Dynamic Loads
FIG Working Week 2009
Surveyors Key Role in Accelerated Development
Eilat, Israel, 3-8 May 2009
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