Jerky Motion of Scissor 0 to 90

Hello Guys,
we are trying to remotely troubleshoot a servo valve(ATOS) with delta motion controller (RMC75E).
the valve behaviour is excellent from 0 to 35, 35 to 0 , 0 to 45, 45 to 0. however , when we are going from 0 to 90 degrees, there appears to be a small but noticable breaking activity at what seems to be 45 to 60 degrees, which looks like a jerky motion.
just for general information, the velocity is 150 pu/s accell rate: 85 pu/s and decel rate is 75 pu/s. proportional gain is 6, integral gain is 45 and differential gain is 0.
any suggestions into which topics i should look into to troubleshoot this?

Gain scheduling looks like it would be a good fit for your application. If one set of tuning gains works well in the 0-45 degree region and another set works well in the 45-90 region something like this would work very well: RMCTools Help

Basically we look at the current position and based off that position we change our gains. If no set of gains is working for the 45-90 degree region we might need to go into second order tuning. But I think gain scheduling will be a good fit.

What are your thoughts?

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