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30 June 2012

Windmill Software Ltd
Data Acquisition Intelligence

The Newsletter for PC-Based Data Acquisition and Control
Issue 167           June 2012
--------------------ISSN 1472-0221----------------------

Thanks for subscribing to Monitor.  Today we have a 
story about how researchers are using a portable Windmill 
strain package to aid the accurate fitting of prosthetic 
limbs to amputees.  Their findings will benefit patients, 
in terms of comfort, and save doctors' time and money.

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Monitor Newsletter

* Windmill Notes: Windmill Strain Package aids fit of 
  Prosthetic Limbs 
* Windmill News: Download the new data acquisition leaflet
* Excel Corner: Displaying time stamps as seconds
* DAQ News Round-up

Windmill Notes: Windmill Strain Package aids fit of 
Prosthetic Limbs by recording strain

British researchers are designing tools to help fit 
prosthetic (artificial) limbs to people, increasing 
their comfort. Accuracy of fit remains the single most 
important factor affecting amputee satisfaction. 

The quality of fit depends on how pressure is distributed 
around the limb and socket interface.  There should be 
no pressure on the sensitive regions where the bone is 
close to the surface; all the pressure should be supported 
by the limb's areas of thick tissue.

Until now, pressure data could only be collected by either:
- inserting a sensor into the socket/limb interface, which
  affects the results collected, or 
- by modifying the socket to insert the pressure transducer, 
  making it unsuitable for everyday use. 
The researchers from Bournemouth University, the University 
of the West of England and the Disablement Services Centre in 
Southmead Hospital, though, have found a third way without 
the drawbacks of the other two.  They are using artificial 
intelligence to determine the pressures at the 
limb/prosthetic socket interface.

Artificial neural networks (ANNs), like people, learn by 
example.  An ANN is configured for a specific application 
through a repetitive learning process.

Relationship between Strain and Pressure
To find the relationship between the surface strains and 
internal pressures, the artificial neural network requires 
a transducer that can reliably measure a strain response on 
the socket due to the internal pressure.  The pressure and 
strain data must then be stored as ANN input and output pairs. 
This requires a loading device for applying known pressures 
inside the socket.  The engineers decided to use strain 
measurement which produces reliable and repeatable responses.  
To do this they attached strain gauges to the socket surface, 
and had to choose carefully the best method.

Capturing the Strain Measurements
A transducer usually used for measuring strain underwater 
fitted the bill for the experiments.  This is a resin encased 
stacked strain gauge rosette, giving three separate strain readings 
at 0, 45 and 90 degrees. The rosette is stuck to a plastic plate 
and the researchers used a standard hot glue gun to bond the 
transducer to the prosthetic socket via the plastic plate.

They chose a 751-SG strain monitoring and control 
data acquisition system to capture the strain data with a 
resolution of +/- 1 microstrain. The 751-SG package comprises 
Windmill software, a USB unit which provides differential inputs 
to monitor 16 strain gauges at up to 80 samples per second, and 
a strain gauge connection box. The Windmill software automatically 
monitors the strain gauge's excitation voltage and performs a 
bridge calculation to produce a reading in microstrain.

Strain measurement

Eight USB units can be connected to one laptop to monitor up to 
128 strain gauges. A portable system was required as the 
strain data was to be captured in a clinical environment. 
The Windmill USB unit was attached to a laptop. 

The researchers wrote their own software in Visual C++ utilising 
Windmill's IML Tools' Active X controllers, and ANN theory, to 
generate the code.

Right First Time Socket Fitting
They concluded that their methodology can aid "right first time" 
socket fitting which will benefit both the patient in terms of 
comfort and the prosthetist by reducing the time and associated 
costs of providing a high level of socket fit.

The 751-SG package is currently on special offer, 
reduced from £775 to £475, and is available at

Further Reading
Static and dynamic pressure prediction for prosthetic socket 
fitting assessment utilising an inverse problem approach 
Philip Sewell, Siamak Noroozi, John Vinneya, Ramin Amalib, 
Stephen Andrews. Artificial Intelligence in Medicine 
Volume 54, Issue 1, January 2012, Pages 2941

IML Tools Active X Controls

Windmill 751-SG Strain Gauge Measurement Package

Tips and Techniques for Measuring Strain

Windmill News: Ethernet Data Acquisition Leaflet now Available

You can now download our leaflet telling all 
about the new 851 Ethernet data logger at


Excel Corner: Displaying Time-Stamps as Seconds

"Hi, I have a problem with my Excel sheet. How can I 
change the time settings to only show seconds?"

Assuming your time settings are in the format hh:mm:ss 
then you would multiply this by 24*60*60 (86400). This 
is because time is stored internally in Excel as a 
fraction of a 24-hour day. For example, Excel sees 
12:00 as 0.5 of a day. To convert to seconds you 
multiply the time by the number of seconds in a day: 
ie by 24 (hours in a day) * 60 (minutes in an hour) 
* 60 (seconds in a minute) or 86400.

For more Excel tips and tricks, see

Ask us an Excel measurement question: fill in the 
form in the Excel page. 

DAQ News Round-up

Welcome to our round-up of the data acquisition and 
control news.  If you would like to receive more 
timely DAQ news updates then either follow us on Twitter at!/DataAcquisition
or grab our RSS newsfeed at

Bot with boyish personality wins biggest Turing test
   Eugene Goostman, a chatbot with the personality of a 
   13-year-old boy, won the biggest Turing test ever staged, 
   on the 100th anniversary of the birth of Alan Turing. 
   Held at Bletchley Park, UK, where Turing cracked the 
   Nazi Enigma code during the second world war, the test 
   involved over 150 separate conversations, 30 judges, 
   25 hidden humans and five elite, chattering software 
   programs. First conceived by Turing in the early 1950s, 
   the test is the most famous evaluation of machine 
   intelligence. Human judges converse via a text interface 
   with both hidden bots and humans - and say in each 
   case whether they are chatting to a human or machine.
   Source: New Scientist

Understanding ISA-84
   The International Society of Automation (ISA) has issued 
   a guide to understanding ISA-84, addressing the need for 
   improved understanding and harmonisation of risk reduction 
   approaches in computer controlled manufacturing.
   Source: The International Society of Automation
Kinect system keeps track of household objects 
   Fitting your house with a network of Kinect sensors could 
   mean never losing your wallet, TV remote or other small 
   items again.
   Source: New Scientist

Tiny data loggers help show how bird society works
   The tiny data logger fitted to a great tit's leg is one 
   of thousands that researchers are using to study "social 
   networks" in birds. As well as finding out exactly how 
   bird society works, the study could shed light on factors 
   that have an impact on the birds' survival. These include 
   how diseases are spread between individuals and how easy 
   it is for the animals to find food or mates.
   Source: BBC
Technology could monitor hip replacements for signs of wear
   A new device could monitor hip replacements for signs 
   of wear, powered only by the movement of the user' s 
   walk. The technology, designed to fit inside a typical 
   prosthetic hip joint, uses a piezo-electric device that 
   generates up to 3.7V of electricity as the user walks 
   to power a strain gauge and a transmitter.
   Source: The Engineer

* Copyright Windmill Software Ltd
* Reprinting permitted with this notice included
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Windmill Software Ltd, PO Box 58, North District Office,
Manchester, M8 8QR, UK
Telephone: +44 (0)161 833 2782
Facsimile: +44 (0)161 833 2190
E-mail: [email protected]


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