[email protected] Whole Body Dosimeters
How [email protected] Seat compares to existing devices?
[email protected] Seat is easy to use and can be purchased at a very reasonable price. Any person involved in OSH – even without in-depth knowledge into vibration measurements – can efficiently setup and use the device to get reliable vibration exposure results.
[email protected] Seat is dedicated to whole-body vibration.
It’s not a general purpose device that would allow other type of measurement such as hand-arm vibration exposure for example.
The option taken during the development of [email protected] Seat was to dedicate it to whole-body vibration measurement. This has allowed us to automate the whole process of whole-body vibration measurement and to make it reliable, simple and affordable. All the know-how of INRS (Research Center for Safety, France) has also been integrated into the [email protected] Seat whole-body vibration dosimeter, making it a perfect choice for people involved in OSH.
What is the automatic rejection of unwanted effects?
In every measure there may be unwanted effects or events occuring during the measurement that generate false acquired values, which in turn may affect or impact the computations and hence the final results. Basic data must then be sorted and only unaffected basic values kept for results computations. This is the case for whole-body vibration measurements.
For example, the driver creates shocks on the sensor when sitting or leaving its seat. Those shocks generates accelerations levels which have nothing to do with the driver’s exposure to vibration. Basic measures taken during the short time period when the driver is sitting or leaving its seat must be discarded in order to get to a valid exposure value.
The [email protected] Seat detects those type of events and automatically sort measures accordingly and hence, computes and displays reliable exposure values.
Some drivers look back to do their work, torsioning or streching their back. In some cases drivers bend to access commands or devices. Those movements combined with high level of vibration or shocks show increased effects on the human body.
When adding commands or devices into the cabin make sure that they are easily accessible by the driver.
Make sure that the vehicle and particularly the seat is checked and correctly maintained on a regular basis and according to manufarcturer recommandations.
Suspended seats lifetime is often shorter than the one of the vehicle.
The best vibration rejection is implemented using a suspended cabin or chassis, combined – if possible – with a suspended seat. In some cases a suspended seat might be enough to attenuate vertical vibrations.
Different type of suspension exist (mechanical, pneumatic, etc); they must be adapted to the type of vehicle.
The seat must exhibit accessible adjustments allowing the driver to easily adapt its driving position to its size, weight and confort according to manufacturer’s recommandations.
When purchasing seats, select a type that has been tested for the type of vehicle you want to mount them on.
If not correctly chosen, a seat may increase the vibration level instead of reducing it!
Seat adjustment to driver’s weight is capital. Adjusting the seat to its weight, the driver set to suspension to mid-range. This is the basic requirement for the suspension to operate correctly.
Drivers sometimes don’t use this adjustment correctly: they use it as a height adjustment, impacting the suspension stroke and hence its efficiency.
Pneumatic suspension automatically adapt seat rest position to mid-range.
Forward/backward and tilt adjustments are also important. Those allow the driver to set a correct position for commands access.
Slopes, bumps, and steps on the driving surface increase the risk.
Don’t underestimate the tyre selection. Good tyres filter out ground roughness.
Excessive speed increases the effect of vibration especially when driving on bad surfaces.
Evaluation of exposure to vibration
Vehicle manufacturers declared vibration values are useful when purchasing a new vehicle. Be aware that they may underestimate the severity of real exposure under given circumstances (i.e. when executing particular tasks).
More accurate exposure values resulting from large-scale measurement campaing can be found over the internet.
But only measurements done on a given vehicle, driven by a driver on a given surface and performing given tasks allows to know exactly the vibration exposure level without any assumption.
A easy-to-use device like [email protected] Seat allows to perform those measurement very efficiently.