Tunning Servo Motor- Linear Voice Coil Motor. Motion Control 7432. Motor Drive 7652

[dazal]

Hi All,

I a bit confused. The step response of my system appears to have a 0ms rise time 3ms peak time and 1% overshoot. However when I run the bode plot function my -3dB point is at around 3 rad/s (The linear shaft oscillates rapidly). I was wondering which of these is the more reliable measure of system performace. How are they both generated in Measurement and Automation and what the possible sources of error would be for th differences in these values. It doesn't make much sense that this would be on a response of 0.5Hz.

Thanks for all your help to date.

Regards,

Darren

[Maclean]

Hi Darren,

The step response of your system is a graph of the encoder feedback when the motor is moved a defined number of steps as quickly as possible.  The bode plot is acquired by oscillating the motor at increasing frequencies, and plotting the magnitude and phase offset of the encoder feedback. They measure different aspects of the motor control, and while there are transfer functions to predict the step response from the known bode plot, the bandwidth of the bode plot does not determine the peak time of the step response. For more information about the two graphs, refer to the links below.

Bode Plot
Step Response

Hope this clears things up!