MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

Basic Information on Acceleration Measurements
Using the MSR145 and MSR165 Data Loggers
1

Introduction/Overview

Measuring physical impacts is of great importance in many fields of application in order toobtain information on mechanical loads and the stresses on objects such as goods,
merchandise, workpieces, parts etc.
The causative loads, which have arisen as a result of external influences, are to be regarded
as largely independent from the examined object. In contrast, the resulting stresses
impacting on the object are directly dependent on the examined object and can only bedescribed with reference to the specific object.
An important parameter for evaluating impacting stresses is the dynamic mechanical load,
i.e. the chronological sequence of the acceleration impacting on the object. It can beappropriately measured by means of acceleration sensors of different designs and grades,
as well as recorded for further analysis, using data memories.
These sensors are, for example, used for transportation monitoring, fault diagnoses and load
tests.

2

Table of Contents

1

Introduction/Overview ..................................................................................................... 1

2

Table of Contents ........................................................................................................... 1

3

Definitions ...................................................................................................................... 2
3.1

Acceleration Data Logger ........................................................................................ 2

3.2

Acceleration Measurement ...................................................................................... 3

3.2.1

Sensors ............................................................................................................... 3

3.2.2

Positioning ........................................................................................................... 4

3.2.3

Vibration .............................................................................................................. 4

3.2.4

Jolt/Shock ............................................................................................................ 5

3.2.5

Damage Boundary Curve .................................................................................... 7

3.2.6

Measurement Frequency/Sampling Rate/Fast Peak ............................................ 9

4

Measuring Acceleration Using the MSR 145 and MSR165 Data Loggers ......................11

5

Further Advice ...............................................................................................................12© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

1

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch3

Definitions
3.2

Acceleration Data Logger

An acceleration data logger is an automatic recording and measuring device, whichautonomously records stochastic shocks or vibrations over a specific period of time in theform of unbiased raw data. Once recorded, the shock and vibration data can be retrieved,
viewed and analysed.

Figure 1: MSR165 data logger with integrated acceleration sensor and microSD card

An acceleration data logger is comprised of acceleration sensors, a data storage device, a
processor and a power supply. The sensors measure the acceleration currently impacting on
the sensor, e.g. when subjected to a shock or vibrations. In the process, the individual
measurements are taken at specific time intervals and stored together with the respective
time value. These measurement frequencies can be arbitrarily chosen between 1
measurement every few seconds and measurement frequencies in the high kHz range (e.g.
5 kHz – 1 measurement every 5,000-1 sec) depending on the sensor type. The higher themeasurement frequency, the finer the resolution with which the actual development of theacceleration event is recorded. The disadvantage of high measurement frequencies is thatthey generate very high volumes of data, meaning that the storage capacity and performance
limit of the logger are quickly reached. In particular, continuous measurements as well asprocessing and storage of the data necessitate high power requirements, which limits themobile operating times of the logger.
The processor in the data logger processes the measured data and saves it to the storage
medium together with the respective measurement periods. This means that the data can be
retrieved after measuring has taken place, either directly on the logger or via a computer
port. Software illustrates the measured data in tables or charts and provides functions foranalysing the measured data. A popular analysis method is the acceleration-time chart with
DBC (Damage Boundary Curve – see p. 8.).
The shock and vibration data can also be recorded based on events that meet specificcriteria. With an event-based measurement, you can specifically record shocks that exceed acritical time period or magnitude. In addition to providing better clarity for long-term
measurements, this has the benefit that only relevant events are recorded and therefore
energy and storage capacity are used more effectively.

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

2

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

Acceleration data loggers usually use non-volatile storage media to save the measured data.
Therefore the measured data is preserved, even if the power supply fails.
[Source: Excerpts from Wikipedia, amended by MSR Electronics GmbH]For more detailed information on the measurement and evaluation of dynamic mechanicalloads, such as transportation monitoring by means of automated recording devices formeasuring stochastic shocks, please refer to DIN EN 15433-6, for example.

Acceleration data loggers are, for example, used for the following:






Monitoring delicate and valuable goods during transportation or storage.
Measuring acceleration in motor vehicles, for example when reconstructing roadtraffic accidents. .
Monitoring production machines that are sensitive to shocks and vibrations during
operation.
Determining dynamic loads for and impacting on people.
Determining acceleration for objects on conveyor belts

3.2

Acceleration Measurement

Acceleration usually refers to dynamic signals. This often involves frequencies within therange of 100 Hz … 50 kHz. Acceleration signals can be caused by vibrations and shocks or
knocks.

3.2.1 Sensors“An acceleration sensor (also referred to as acceleration meter, accelerometer or g-sensor)
is a sensor that measures its own acceleration. This is usually done by determining the force
of inertia impacting on a test mass. This is how it can be determined whether acceleration or
deceleration takes place. Acceleration sensors belong to the group of inertial sensors.
[Source: Wikipedia “Beschleunigungssensor (‘Accelerometer’)”]To measure acceleration, we use sensors with different measuring principles, usually with
piezoelectric sensors or a MEMS (Micro-Electro-Mechanical System) structure. Thesesensors often weigh only a few grams and have working ranges from just a few g to 1,000 g
or more.

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

3

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

3.2.2 Positioning
In order to determine the position of the object (upright, horizontal, on the side and all
positions in between), three acceleration sensors are required. Preferably they are locatedperpendicular to each other along axes x, y and z of the object; they measure the effectively
static, ordinary acceleration of gravity along the axis. If the object changes its position, thepercentages of the acceleration of gravity per axis change.

Figure 2: Axes when positioning

3.2.3 Vibration[Source: Wikipedia and MSR Electronics GmbH]

Vibrations are periodic (mechanical) oscillations of matter and objects, usually at medium tohigh frequencies and low amplitudes. The vibrations are described by their frequency. In
addition, the maximum accelerations the device is subjected to are specified. They areusually specified as a multiple of the acceleration of gravity. At low frequencies the vibration
is not defined by means of the acceleration but the amplitude (deflection) of the object.
Depending on the frequency range of the vibration, the occurrence of mechanical vibrations
over longer periods of time may result in material fatigue.
For example, particularly strong vibrations impact on compressors and mobile workmachines or during very “bumpy” transport. The acceleration data logger measures andrecords vibrations as a chronological sequence of individual g-values. The time between theindividual measured values is determined by the measurement frequency (number ofmeasurements per time unit).

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

4

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.chPlease note:
In order to be able to correctly record vibrations by means of acceleration sensors, we mustselect appropriately high measurement frequencies that are suitable for the vibration.
Otherwise, if there are high vibration frequencies on the measuring object, it is possible thatthe vibration is mapped inadequately (see figure 3 and subsection 3.2.6).

Figure 3: Oscillations – resolution at a lower and higher measurement rate

3.2.4 Jolt/ShockIf an object is subjected to individual major changes of velocity (accelerations) of shortduration, this is referred to as a mechanical shock. This happens, for example, during car
accidents or after a fall, when the object hits the ground and is decelerated abruptly.
Shocks are specified as a multiple of the acceleration of gravity [g=9.81m/s²]. Furthermore,
the duration of impact of this load is stated. Standard values measure up to several hundred
g for a few milliseconds.
Shocks are characterised by the following:

Acceleration axes x, y and z of the three measuring directions that are perpendicular
to each other






Acceleration values ax, ay and az in the direction of the acceleration axes
Acceleration peaks for the x, y and z axes or the space vector
Main axis xyz(max) – axis with the greatest acceleration peak â (point 1 on fig.4)
Acceleration value aR of the randomly aligned space vector of the acceleration of theshock event

=

+

+

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

5

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

Shock duration TShock – (point 2 on fig. 4) Time during which the acceleration value ofthe main axis is equal to or greater than 10 % of the peak acceleration value of thisaxis (see figure below)

Accelerationaxyz(max)

Shock eventâxyz(max)

athreshold

Trigger threshold for event logging

10%*âxyz(max)Time

TShockFigure 4: Typical sequence of a shock event[Based on the source: DIN EN 15433-6:2008-02]
15433

Examples of external shocks impacting on the load during transport:[Source: Load-security
security information system (LIS), BAM, effective: June 2003]

Means oftransport
Road vehicles(lorries)
Rail vehicles
Rail vehicles
Sea vessel

Horizontal
orizontal acceleration
Opposite toTransverse to
In direction
the direction
the directionof travelof travelof travel

Vertical
ertical acceleration
Up

Down

0.8 g

0.5 g

0.5 g

n.s.

1.0 g

4.0 g
1.0 g
0.4 g

1.0 g
1.0 g
0.4 g

0.5 g
0.5 g
0.8 g

0.3 g
0.3 g
n.s.

n.s.
n.s.
n.s.

Chart: maximum acceleration on transport carriers.
[Source: DIN EN 15433-6:2008-02
02 and MSR Electronics GmbH]

Transport mode
Road, e.g. potholeRail, e.g. shunting
shocksWorking range [m/s²]
100

Shock duration [ms]5Frequencies [Hz]approx. 10 to 15

100

20

approx. 120© MSR Electronics GmbH, Aug. 2017, all rights reserved.
reserved It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.
part.

6

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

As every load/object responds in a specific way to impact, as a general rule, both themechanical stress and the actual impact on the object should be determined experimentallyby means of acceleration sensors, (preferably) during real stress (e.g. transport).
In the event of a shock, knowledge of the acceleration peak is often not sufficient; in fact, therespective duration of the shock is equally relevant, as it can be used to determine theintensity of the shock, either directly or in comparison with other shocks to the object.
In the chart above, the intensity (also: “magnitude”, “pulse”, “energy”) of the shock is
indicated by the area below the curve above the time axis. A large area signifies an intense
shock, which usually indicates a shock lasting a “long” time with high acceleration values.
Background:
The time integral of the acceleration within the shock duration TShock corresponds to theobject’s change of velocity related to the shock event:∆ =The object velocity=()

can be found in the formulae for the pulse I∗

and for the kinetic energy E=

2

and is therefore the variable element in the specific object shock.
Please note:
Two shocks with the same area may have a different impact on the object as the absolutevalues of the shock duration and acceleration always determine the impact on the object aswell.

3.2.5 Damage Boundary Curve[Source: Wikipedia and MSR Electronics GmbH]The damage boundary curve (DBC) is a method used to detect damage to an object causedby shocks. The DBC divides a shock chart into two areas, a non-critical and a critical shockarea. A shock that touches the critical area may have a destructive effect on the object.

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

7

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.chTheory:Figure 5: Shock chart with a critical, potentially damaging shock (shock 3)

For a shock to become critical, it must have a certain minimum acceleration gmin(shock) anda minimum duration tmin(shock). What is critical for a specific object differs from object toobject, and depends on its respective state. Depending on how sensitively an object
responds to shocks, the DBC in the chart will present differently. If the chart contains a shockthat touches the critical area, we have to expect damage to the object.
Therefore, in order to facilitate an appropriate classification of the loads impacting on an
object, we must specify the critical conditions for the minimum duration and minimum
acceleration. If necessary, these combinations must be determined experimentally in the runup. Test specifications for this can, for example, be found in DIN EN 15433 et seq.
Practice:
Shock charts with DBC are used, for example, in order to examine delicate and valuable
goods transports, load impact on objects in production facilities or load impacts on production
machines during operation. To this end, acceleration data loggers record shocks that impact
on the object to be examined. The recordings are presented in a shock chart. Depending on
the design of the loggers, only shocks relevant to the DBC are recorded or, within the scopeof the analysis of all recorded data, the lower limits for acceleration and duration can be
specified for the analysis.

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

8

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

3.2.6 Measurement Frequency/
uency/Sampling Rate/Fast PeakAn acceleration measurement is determined by the working range of the acceleration sensor
and the possible or applied measurement frequency (also referred to as sam
sampling rate) forthe measurement. The working range describes the maximum g-values
values that can be recorded(e.g. ± 200 g). This range is specified for each sensor type, depending on its design.
Depending on the measuring task, an acceleration sensor with the respective working range
must be selected.
The measurement frequency
equency or sampling rate describes the number of g
g-valuemeasurements per time unit (usually per second – in the unit of Hz). The measurement
frequency predetermines the accuracy of recording the acceleration event. When detectingchanges of position, a relatively
latively low measurement frequency is sufficient as the processes
involved are often slow. Shocks and vibrations, however, require as high a measurement
frequency as possible in order to properly map the g-value
g value developments of the event. The
higher the measurement
asurement rate, the more accurately the actual development is mapped.

Figure 6: Resolution of a shock event with a low and high measurement frequency [Hz]Figure 7: Resolution of several shock events with a low and high measurement frequency [Hz]© MSR Electronics GmbH, Aug. 2017, all rights reserved.
reserved It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.
part.

9

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

In figures 6 and 7 we can see that at a low measurement frequency (50 Hz), information on
the development and the peak acceleration values of the shock event(s) are recorded poorly(figure 6) or not at all (see figure 7). This is not the case at a high measurement frequency(1,600 Hz). Development and peak values are mapped better and accordingly, they can beanalysed in a meaningful manner (please note: the peak values mapped in figure 6 arelimited to 16 g due to the logger design).
However, the disadvantage of a high measurement frequency is that, if measurements aretaken continuously, this generates an accordingly large data volume, which quickly depletes
the memory capacity of the acceleration data logger and therefore significantly limits its
period of application. In particular if the focus of the measurement task is not on short-term
shock and vibration analyses, but on long-term monitoring, e.g. during transport processes,
this is undesirable. Here it is only the event causing damage that is supposed to be recorded
as accurately as possible.
In order to implement this task as effectively as possible, generally the following approaches
are widely used:
1. Only events that exceed a specific pre-set g-value and minimum shock duration arerecorded and stored. Here it is meaningful to also store a few g-values that are
chronologically before and after the event (e.g. 32 measured values) so as to be able
to analyse the data for the entire event. This approach saves memory capacity as
only the relevant events are stored. However, this requires a good knowledge of therelevant events so as not to lose any interesting events in the recording as a result of
the pre-setting.

{0><}0{>Pre-setting
for relevant events<0}{0><}0{>Events notrecorded<0}Figure 8: Relevant events with pre-set g-value threshold

2. With the “fast peak” feature, the measurement frequency is pre-set, e.g. to 1 KHz.
Then an arbitrary measurement interval is selected, at the end of which the maximum
g-value for acceleration measured during the interval is stored. The measurement
interval (=storage rate) can, for example, be set from “maximum of 50 storage actions
per second” through to “store once every 12 hours”.

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

10

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

For example, if a storage rate of 1/s is selected, the acceleration is sampled at 1 KHz
and the maximum value (= peak value of the last 1,000 measured values) is stored
once per second.

Figure 9: Comparison of high measurement frequency vs. fast peak – peak values of the event

Figure 9 shows very well that, with respect to the peak values of the event, the fast peakmethod returns good results. However, the development of the relevant shock event is notrecorded and is consequently lost. In applications, where only the peak values of the load
and its direction are of importance, this method is well suited for preserving the storage
capacity without running the risk of failing to record relevant events due to unfavourably preset thresholds. However, peak g-values that are not of interest are also continuously
recorded during the set time interval.

4

Measuring Acceleration Using the MSR145/MSR165 Loggers

The range of a data logger must always be specified with respect to the required
measurements.
MSR145 data logger for measuring minor shocks
In order to determine acceleration values, which occur for example during transportation on
the loading platform of a vehicle, a relatively small working range is generally sufficient. To
monitor a pallet shipment, for example, i.e. to measure minor shocks (< ±15 g), the MSR145
mini data logger is therefore generally very well suited for this task. In particular the “fastpeak” model is used in this segment as the peak values of the shock are recorded at ameasurement frequency of 1 kHz over the entire measurement period. Subsequently themeasured data is analysed using the “MSR Viewer” PC software by MSR. Tools can be used
to export the data into the MATLAB or CSV format.

© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

11

MSR Electronics GmbH • Mettlenstrasse 6 • CH-8472 Seuzach, Switzerland
Phone. +41 52 316 25 55 • Fax +41 52 316 35 21 • info@msr.ch • www.msr.ch

MSR165 for short, more intense shocks and a more detailed shock analysis
For vibration measurements and in particular for short, more intense shocks, e.g. 75 g with 8
ms, which may occur during individual shipments, the MSR165 data logger, which isrecommended specifically for transportation monitoring, is more superior to the universal
MSR145. With 1600/s (± 15 %), the MSR165 allows the user to take a significantly higher
number of measurements than the MSR145 (50/s); therefore, transportation stresses can be
identified with a far greater resolution. Shock monitoring using the MSR165 is also possible
up to a maximum of ±15 g or alternatively up to ±200 g. The memory of the MSR165 iscapable of storing 2 million measured values, which is sufficient for recording more than
10,000 shocks; the memory capacity can be extended to more than 1 billion measured
values by using a microSD card. Bonus feature: 32 measured values are stored before theactual event.
With the MSR165, shocks are analysed using the “MSR ShockViewer” analysis software.
Compared to the standard software of the MSR145 data logger, this software, which
specialises in shock analyses, offers far more extensive analysis options. With the MSR
ShockViewer, you can clearly present even extensive recordings and analyse critical shock
events in detail. This way you can examine both the data curve and the measuring points ofevery individual shock and export the data. All measured values are given an exact“timestamp”, which can be used to reconstruct the time of an event accurately to the second.
Other environmental data, such as the temperature, humidity, pressure and light can also beviewed and organised clearly in a chart in the MSR ShockViewer. A single click is sufficient
to call up a report.
Data Logger Type

Working Range

Measurement
Frequency

Storage Rate

MSR145±15 g;-20...+65 °C

50/s to every 12 h

50/s to every 12 h

MSR145 Fast Peak

±15 g;-20...+65 °C

1000/s (fast peak)
50/s to every 12 h

50/s to every 12 h

MSR165 Shock Mode

±15 g; -20...+65 °C±200 g; -20...+65 °C

1600/s to 100/s

1600/s to 100/s (onlythe relevant events)

MSR165 Vibration Mode

±15 g; -20...+65 °C±200 g; -20...+65 °C

1600/s to every 12 h

1600/s to every 12 h

Table: Measurement of 3-axis acceleration using the MSR145 and MSR165 data logger types

11

Further Advice

Please note that this Statement of Basic Information is not a substitute for the professional
advice provided by an MSR sales representative; furthermore, all information is subject tochange, errors excepted. For a personal consultation, please contact one of the 90 MSR
sales partners in over 50 countries around the world: https://www.msr.ch/en/contact/© MSR Electronics GmbH, Aug. 2017, all rights reserved. It is forbidden to reproduce, disseminate, modify or make thisStatement of Basic Information accessible to any third parties, whether in whole or in part.

12