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XPS-Q8 Controller
16.0
Excitation Signal
XPSDocumentation V1.4.x (EDH0301En1060 — 10/17)
16.1
Introduction
The excitation-signal function generates a typical signal (a sine, a blank noise or an
echelon signal) that the controller sends to motors to excite the system. In measuring
the output signal of the excited system, we can determine some system characteristics,
such as the system transfer function.
16.2
How to Use the Excitation-Signal Function
The PID excitation-signal function is only available with the stages controlled in
acceleration (acceleration control, ex: brushless / linear motors), velocity (velocity
control) or in voltage (voltage control). It is not used with the stages controlled in
position (ex: stepper motors).
The excitation-signal function PositionerExcitationSignalSet can be executed only
when the positioner is in the "READY" state. When the excitation-signal function is in
process, the positioner is in the "ExcitationSignal" state. At the end of the process, the
positioner returns to the "READY" state (see group state diagram).
This function sends an excitation command to the motor over a time period. This
function is allowed for "PIDFFAcceleration", "PIDFFVelocity" or
"PIDDualFFVoltage" control loop. The parameters to configure are signal type (0:sine,
1:echelon,2:random-amplitude,3:random-pulse-width binary-amplitude, integer),
frequency (Hz, double), amplitude (acceleration, velocity or voltage unit, double) and
during time (seconds, double).
The effective functional parameters for each mode are: (Limit means AccelerationLimit,
VelocityLimit or VoltageLimit) :
– Sine signal mode : Frequency (>=1 and <= 5000), Amplitude (>0 and <= Limit),
Time(>0)
– Echelon signal mode : Amplitude (>0 and <= Limit, or <0 and >= -Limit), Time
(>0).
+ During Time :
+ End of Time :
-
Random-amplitude signal mode : Amplitude (>0 and <= Limit), Time(>0),
Frequency (>= 1 and <= 5000).
The signal is generated with a random value at every controller base time (Tbase =
0.1 ms), then is filtered with a second order low-pass filter at the cut-off Frequency
value.
o Random-pulse-width binary-amplitude signal mode :
Amplitude (>0 and ≤ Limit), Time (>0), Frequency (≥1 and ≤5000).
The signal is a sequence of pulses (Signal = Amplitude or = 0) with the pulse
randomly varied in width (multiple of Tbase).
Frequency is the controlled system band-width (cut-off frequency), necessary for the
PRBS (Pseudo Random Binary Sequence) function configuration.
The non-effective functional parameters can accept any value, the value 0 is
recommended for simplicity.
The PositionerExcitationSignalGet() function is used to get the parameters previously
used with the PositionerExcitationSignalSet() function.
Signal = Amplitude
Signal = 0
190
Motion Tutorial
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