Novatech's revolutionary Hand Brake Loadcell design.
Measuring forces in mechanical systems where forces
are aligned and transmitted through engineered structures
is a relatively simple matter compared to measuring forces
generated by human body part interactions where
ergonomic aspects play havoc with the arrangement of
force transmission.
Investigations into handbrake operation efficiency and ergonomic
forces require the actual force applied by a hand to the handbrake
lever to be measured. The force applied varies with size of
occupant, seating position and handbrake mechanism adjustment.
The loadcell design had to take into account :
1. Uneven force distribution over a typical four finger grip.
2. Variation in force centre position with lever movement.
3. Non intrusive dimensions for adaptation of handbrake lever.
4. The ability to minimise the effect of the resultant force vector
changing in direction relative to the handle by inbuilt extraneous
force immunity, maintaining force measurement in the normal axis
only.
By designing a handgrip shroud the force transmission is routed
either side of two shear sensing elements which are arranged to
sum the reaction in total.
Due to summation and the shear sensing element immunity to
moment and extraneous forces the normal reaction is measured
accurately despite ergonomic induced variation in how the force
is applied.
The loadcell has been incorporated into the handbrake lever for
R & D investigation and also used as a production tool where
a moulding has been produced which fits over the production
car's hand grip.
Typical performance:
Rated load 1600 N
Extraneous forces < 0.5% AL
Linearity < 0.03% RL
Hysteresis < 0.03% RL
Please contact David Harris or Andy Pitcher at Novatech for
further information.
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December 2002
