However, the three control loops for position, speed and current are closed behind
the interpolation. Thus the parameterization of co10 does not have any effects on
the three control circuits.
At least four points are necessary since the precontrol values for speed and accel-
eration are calculated from the position setpoints by two-fold differentiation.
The type of initialization of the interpolator is selected with bit 4 in co10.
The setting "actual value" is favourable, if the mode change shall be made at
standstill.
Value 16 "target value" should be selected if the operating mode shall be changed
during operation.
For initialization with setpoints, new setpoints must be preset via co19 even before
mode changeover. The number of setpoints, which must be preset at least before,
is depending on co10: Number of setpoints = number of points -1.
This means: if co10 = 5 "B-Spline, 5 points average“, the setpoint must be written
4-times to co19 before mode changeover.
The function blocks torque limiting and selection of the torque offset are described
in chapter 4.8.8
4.8.5.1 Position precontrol
In the Cyclic Sync Position Mode, the spline interpolator causes a temporal shift
between the position setting by the higher-level control co19 (CiA 0x607A) target
position and the actual set position for the motor ((CiA 0x6062) st37 demand posi-
tion).
The time is made up from the process data communication and the setting of fb10
and co10.
This is a known time and it can be set for all axes. Then the track profiles are pro-
cessed exactly synchronously on all axes with this constant deceleration.
If desired, the position offset between co19 and st37 can be corrected. Thus the
driving profile has been slightly modified.
The value for co13 can be determined as follow.
The points of the interpolator in co10 are halved multiplied with fb10. Approx. one
clock of fb10 must be considered as deceleration for the process data communica-
tion.
Example: co10 = 4: B-Spline, 4points avg + actual value
fb10 = 1ms
=> co13 ≈ 0.5 * 4ms + 1ms ≈ 2500µs…3000µs
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