Analog DC servo very big response delay

Hi to all,

I have done a retrofit of Mikron WF31CH running Bosch TR-10 230 amplifier and Siemens DC brushed servos 1HU 3070-0AF for X, Y axes and 1HU 3073-0AF.
This drive looks like have a very big delay in input command processing, despite being analog:

Drive manual: www.dropbox.com/sh/8owpaoax31ehf2x/AACji...older_nav_tracking=1
Is there any possibility to fix this? I have found in manual that drive has analog input low pass filter of 11.2 Ohms and 100 nF, which gives time constant of 1.12 ms and cuttoff frequency of 142 Hz. I'm thinking that it's possible to use smaller capacitor to change this, but I'm not sure that this will help much.
Also there is an option to exchange drive to microprocessor based with 8 KHz PWM, speed regulation of 1:10000 and 14 bit ADC, but drive developers can't give exact answer whether this situation will happen too, only experiment can help. I'm having same doubts as them, due to nature of brushed DC servos and DC tachos.

Have anyone encountered similar problem? I know there is a way to exchange with modern digital servos and PMSM motors which will give much better results, but this way is rather expensive.

Thanks!

Have you tuned your drives velocity loop? The nearly 10 ms delay from velocity command to actual motion seems a bit more like stiction combined with low velocity gain than drive bandwidth.

Tuning of this drive is a bit complicated, because it requires soldering capacitors and resistors somewhere on regulator board. It was pretuned for this motors on factory.
It does look like low servo gains on image with Z axis movement, when it tries to move back from overshoot, that takes almost 80 ms.

Looks like I need to find somewhere a RC decade box for the tuning. Once I get it I will comeback with updates.

Hello,

have you tuned the parameter FF1 ?

Sure, cruise ferror is close to 1-2 microns.