The Laboratory of Automotive Prototypes of ULBRA has developed
researches to construct small automotive cars of high efficiency.
The principal aim is to develop and apply new technologies that
allow increasing the efficiency of electric and gas engine cars.
Those cars received the denomination of Camels. This work presents
the results of the study and development of a dynamometer employed
in the measurement of torque produced by a small brushless DC
motor. That motor was applied to drive a small electric car
designed and constructed at ULBRA. Due to difficulties in finding a
load cell to measure loads smaller than 20 N, a ring-type load cell
was constructed to measure static force in uniaxial direction,
range from 0 to 20 N. The load cell had strain gages connected to a
data acquisition system. The acquisition system was connected to PC
via USB. The measurement system consisted of an analog digital
converter (A/D), model MyPCLab, produced by NOVUS. The PC computer
was employed to process and to storage the data produced during the
measurements.
The calibration of the measurement system was made by comparing
the force generated by standard weights. The ratio between
generated data and trend line was R2 = 0.998. That proved the
quality of the load cell. The uncertainty was 0.012 N. The load
cell constructed in this study had sensitivity, repeatability, and
uncertainty suited to be used in the range of work specified in the
design (0 to 20 N).