16 HD65 & HD130 STEPPER DRIVES USER GUIDE
Link 2 is normally in position "a". Moving it to position "b" will cause
a sinusoidal profile to be selected at standstill. With some motors
this will give better static positioning than a filled-out or trimmed
profile. Choosing the optimum profile for a given motor is best
carried out with equipment which will accurately measure shaft
position and torque. Since this is seldom available, empirical
methods are normally used and can give perfectly acceptable
results.
The logical starting point is with all switches off to give a sinusoidal
profile. Attach a light pointer to the motor shaft (cable ties are ideal),
and run the motor very slowly. It will be visually apparent whether
the steps are all similar or there is a cyclic variation in step size as
the shaft rotates. Slowly increase the speed, and the sound from the
motor will give an idea of the relative torque produced on successive
steps. Again a cyclic pulsing sound implies associated torque
variations
Switch off, remove the drive and try setting a trimmed profile (see
table on page 15). Repeat the exercise and compare the results.
From this it should be clear whether more or less trimming is
required, so choose another setting and try again. It is usually best
to aim for the smoothest rotation rather than best static positioning.
If the application demands significant torque from the motor, repeat
the exercise with the motor loaded. This method usually reveals the
useful range of profiles quite quickly.
TRIMMEDFILLED-OUTSINEWAVEFigure 6. Microstepping Current Profiles