February 2014
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is een initiatief van het kenniscentrum Design en Technologie van
Saxion. Het project richt zich op de vraag hoe de veiligheid op de werkvloer te bevorderen met behulp van ambient technologie. Het gaat daarbij om persoonlijke veiligheid, een veilige omgeving en veilig gedrag. Het project is gestart op 1 januari 2011 en heeft een looptijd van vier jaar. De consortiumleden zijn Saxion, Universiteit Twente, Novay, Thales Nederland, Norma
MPM, PANalytical, TenCate Protective Fabrics, Alten PTS en Noldus Information Technology.
Daarnaast is er een wisselende groep van deelnemende bedrijven die bij gelegenheid deelneemt in het programmateam. Het project ontvangt subsidie van de Stichting Kennis Ontwikkeling HBO onder registratienummer RAAK PRO-2-013.
ISBN/EAN: -
Titel: Risicoanalyse en pakket van eisen
Subtitel: -
Auteurs:
Projectreferentie:
Uitgever: Saxion Kenniscentrum Design en Technologie
Verschijningsplaats: Enschede
Verschijningsdatum: 21 februari 2014
Status document:
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INTRODUCTION ........................................................................................................ 4
ELECTRONICS ........................................................................................................... 5
HOUSING .................................................................................................................. 5
THE POCKET ............................................................................................................. 6
CONCLUSIONS AND DICUSSION ................................................................................. 7
REFERENCES ............................................................................................................. 8
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As part of the RAAK project “Protection at the workplace” Saxion was requested to deliver a quick prototype of the integration of a gas sensor in an Enexis overall.
Electronics and battery were given as shown in picture 1 and 2.
Figure 1: Electronics gas sensor;
1 = natural gas sensor
2 = buzzer
3 = 2x LED
4 = on/off switch
5 = Mini USB for charging battery
6 = step-up converter
7 = bottom housing,
* = added by Saxion
Figure 2: Given battery, 3 x AAA
It was immediately clear that the weak part of the construction would be the connection between battery and PCB, being subject to movement continuously. Would it be possible to use a smaller battery, and keep battery and pcb fixed and together in one small housing? The housing can then easily be inserted in a pocket in the overall.
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 Minimum voltage 3.8V due to gas sensor [1]
 Running time with 3 x AAA = 40 hrs.
Principally unaware of the specs of the gas sensor 2 batteries had already been ordered. Finally it was chosen to use LP-443440-1S-3 with a step-up converter added, increasing the voltage from 3.7 to 5. [2]
A mini-USB was added for charging the battery. It is recommended to switch off the sensor when charging the battery.
Around the electronics and battery a simple housing was built, see the pictures below. The dimensions kept to a minimum. The rounded edges are applied to avoid sharp edges in the textile, for durability, visual, and easy insertion reasons.
Figure 4 Exploded view gas sensor
Figure 3 :Assembled sensor housing
Figure 5: Dimensions housing Figure 4: Exploded view gas sensor
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A tight pocket is made around the housing. The pocket is located close to the shoulder:
 Buzzer within hearing distance, also with a noisy environment
 Out of the reach-area when the user uses the pockets at the chest
 Sensor is out of the way when working
 This area is relatively free of external influence: minimal accidental contact with other surfaces when working, keeping the sensor safe and clean.
An alternative position is considered at the hip
 Standard location to carry hardware: within reach, and not in the way
 Use of double layer of textile of reflection stripes.
 Accessible from the outside
Figure 6: Pocket of the sensor, close to the shoulder
Figure 7: Alternative pocket, using the reflection stripes
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A quick prototype has successfully been realized for insertion of the gas sensor in the overall.
The hardware seemed larger than necessary, making the entire unit larger and heavier than necessary. If the electronics is smaller, a smaller battery is also recommended. The smaller the more integrated and less obtrusive. Also other, more accessible ways to switch the sensor on/off are worth considering.
The housing is now top and bottom glued together. A click was integrated assuming smaller tolerances. Assembly top and bottom should be reconsidered and tested with more accurate manufacturing/prototyping methods.
From the two pockets tested the pocket at the shoulder is recommended, it facilitates more freedom for optimal design and sizing of the pocket. For future development it is recommended to think about the insertion/attachment of the sensor in more detail to create a minimal tolerances in positioning of the housing, resulting in 100% alignment of the sensors and holes for contact between sensors and external world. Also the location of the housing should be tested and discussed with the final users.
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[1] Applied Sensors.
. CCF02072014_0000.pdf
[2] Dubilier.
.
BAK - LP-443440-IS-3 - BATTERY, LITHIUM POL, 3.7V, 0.6AH.pdf
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