ElmoMC SimplIQ Analog Servo Amplifiers-Violin Operating Manual - Manual (Page 22)

Elmo Motion Control Rev 09/09 VIO-Velocity - Operating Manual
Page 18
3.10
Response Adjustment (Velocity Mode Only)
In most applications optimum response is achieved by adjusting the compensation (COMP)
trimmer. Adjustment procedure is as follows:
- Provide the amplifier with a low frequency, bi-directional square wave velocity command (A 0.5Hz,
±2V waveform is often employed).
- Apply power to the amplifier, and while monitoring the tachometer signal, gradually adjust the
COMP trimmer from the CCW toward the CW position. Optimum response (critically-damped)
should be achieved at some position before reaching full CW on P3. Fig 8.1 illustrates the types
of waveforms observed for various setting of P3.
In some applications, especially those where the load inertia is much smaller or larger than
normally encountered, the standard compensation components values of 0.022µF for C1 and
475Kohm for R8 may not allow an optimum setting of the COMP trimmer P3. In fact, the velocity
loop may be unstable for any setting of P3.
In these cases different values for C1 and R8 must be chosen. The following procedure can be used
to select these values:
a) - Replace C1 with a short jumper wire.
b) - Replace R8 with a decade resistance box. Initially set the box resistance at 20Kohm.
c) - Set P3, the COMP trimmer to approximately midrange.
d) - Input a 0.5Hz, 2V bi-directional square wave velocity command signal to the amplifier.
e) - Apply power, and while monitoring the tachometer signal, gradually increase the value of
the box resistance until optimum response as depicted in Fig 8.1 is achieved.
f) - Substitute the closest standard value discrete resistor for R8 and remove the decade
resistance box.
g) Remove the shorting jumper, install C1, and again check the response using the square wave
test signal. If near optimum results are obtained, trim the response using the COMP trimmer
P3 for the optimum.
h) - If the previous step does not yield satisfactory results, if unacceptable overshooting has been
noted, substitute a larger value than 0.022µ µ µ µF; or, if the response is over damped substitute a
smaller value than 0.022µ µ µ µF. Repetition of this procedure should yield an optimum choice for
C1.