Delta Tau GEO BRICK LV User Manual

 

When using cascaded servo loops for extended filtering of a single control quantity, several details of the 
setup will be different.  The outer loop will be set up first, using the real feedback device, and writing 
directly to the registers that command the amplifier, commutating if necessary.  This servo loop should be 
tuned as well as possible by itself. 
When ready to engage the inner loop as well, do the following: 
1.  Set Ixx01 for the outer-loop motor to 2 to point the output to an X register.  This also disables 

commutation for the motor if you had been using it before. 

2.  Set Ixx02 for the outer-loop motor to the address of an open register, usually $0010Fx. 
3.  Set Ixx00 for the inner-loop motor to 1 to activate it. 
4.  Set Ixx01 and Ixx02 for the inner-loop motor to the same values you had for the outer-loop motor 

when running it alone.  If commutating with Turbo PMAC, also set Ixx70 – Ixx84 for the inner-loop 
motor to the same values you had for the outer-loop motor. 

5.  Set Ixx24 and Ixx25 flag parameters for the inner-loop motor to the same values you had for the 

outer-loop motor when running it alone. 

6.  Set Ixx03 and Ixx04 feedback address parameters for the inner-loop motor to the address of a register 

that will always be set to 0.  Register $35C0 at the end of the conversion table is suggested. 

7.  Set Ixx05 for the inner-loop motor to the same address as the outer-loop motor’s Ixx02 to pick up the 

intermediate value. 

8.  Set Ixx06 for the inner-loop motor to 1 to enable the use of the Ixx05 register. 
9.  Set the Ixx07 master position scale factor for the inner loop motor to 1. 
10.  Set gain term Ixx30 for the inner-loop motor to 65,536, and Ixx31 – Ixx39 to 0.  This should make the 

inner loop a pass-through and your performance should be the same as with the outer loop alone. 

11.  Now adjust the gains of the inner-loop motor to get the additional filtering you desire. 

Cascaded Loops for Single Quantity Control

Servo

Filter

Amp

M

Output
Device

Servo

Filter

Ixx02

+

Ixx05

Ixx06

ECT

Entry

Ixx02

E

-

(Always Zero)

First PMAC Motor

Second PMAC Motor

Ixx03,

Ixx04

+

-

Actual

Position

ECT

Source

Address

+

Ixx03,

Ixx04

(Always Zero)

Commanded

Trajectory