ini_config.lyx

CNC 的开放码,EMC2 V2.2.8版

 in quasi-SI units to raw actuator values, e.g., volts for an amplifier DAC.
 This scaling looks like: 
\begin_inset Formula \[
raw=\frac{{output-offset}}{scale}\]

\end_inset 

 The value for scale can be obtained analytically by doing a unit analysis,
 i.e., units are [output SI units]/[actuator units].
 For example, on a machine with a velocity mode amplifier such that 1 volt
 results in 250 mm/sec velocity, 
\begin_inset Formula \[
amplifier[volts]=(output[\frac{mm}{sec}]-offset[\frac{mm}{sec}])/250\frac{mm}{sec\, volt}\]

\end_inset 

 Note that the units of the offset are in machine units, e.g., mm/sec, and
 they are pre-subtracted from the sensor readings.
 The value for this offset is obtained by finding the value of your output
 which yields 0.0 for the actuator output.
 If the DAC is linearized, this offset is normally 0.0.
 
\newline 
The scale and offset can be used to linearize the DAC as well, resulting
 in values that reflect the combined effects of amplifier gain, DAC non-linearit
y, DAC units, etc.
 To do this, follow this procedure: 
\begin_deeper 
\layout Enumerate


\color black
Build a calibration table for the output, driving the DAC with a desired
 voltage and measuring the result.
 See table\SpecialChar ~

\begin_inset LatexCommand \ref{cap:Output-Voltage-Measurements}

\end_inset 

 for an example of voltage measurements.
\layout Enumerate


\color black
Do a least-squares linear fit to get coefficients a, b such that
\begin_inset Formula \[
meas=a*raw+b\]

\end_inset 


\layout Enumerate


\color black
Note that we want raw output such that our measured result is identical
 to the commanded output.
 This means 
\begin_deeper 
\layout Enumerate


\begin_inset Formula \[
cmd=a*raw+b\]

\end_inset 


\layout Enumerate


\begin_inset Formula \[
raw=(cmd-b)/a\]

\end_inset 


\end_deeper 
\layout Enumerate


\color black
As a result, the a and b coefficients from the linear fit can be used as
 the scale and offset for the controller directly.
 
\end_deeper 
\layout Description


\color black
MAX_OUTPUT\SpecialChar ~

\series bold 
=\SpecialChar ~
10 
\noun on 
\color default
(hal)
\series default 
\noun default 
 
\color black
The maximum value for the output of the PID compensation that is written
 to the motor amplifier, in volts.
 The computed output value is clamped to this limit.
 The limit is applied before scaling to raw output units.
 The value is applied symmetrically to both the plus and the minus side.
\layout Standard


\begin_inset Float table
wide false
collapsed false

\layout Standard


\begin_inset LatexCommand \label{cap:Output-Voltage-Measurements}

\end_inset 

Output Voltage Measurements
\layout Standard
\align center 

\begin_inset  Tabular
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\begin_inset Text

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Raw
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Measured
\end_inset 
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</lyxtabular>

\end_inset 


\end_inset 


\layout Description


\color black
INPUT_SCALE
\begin_inset LatexCommand \index{INPUT SCALE}

\end_inset 

\SpecialChar ~
=\SpecialChar ~
20000
\color default
 
\series bold 
\noun on 
(hal)
\series default 
\noun default 
 Specifies the number of pulses that corresponds to a move of one machine
 unit.
 A second number, if specified, is ignored.
\color black

\newline 
For example, on a 2000 counts per rev encoder
\begin_inset LatexCommand \index{encoder}

\end_inset 

, and 10 revs/inch gearing, and desired units of mm, we have
\begin_inset Formula \begin{eqnarray*}
input\_ scale & = & 2000\frac{counts}{rev}*10\frac{rev}{inch}\\
 & = & 20000\frac{counts}{inch}\end{eqnarray*}

\end_inset 


\layout Subsubsection

Stepper-related items
\begin_inset LatexCommand \label{sub:Stepper-related-items}

\end_inset 


\layout Description


\color black
SCALE
\begin_inset LatexCommand \index{INPUT SCALE}

\end_inset 

\SpecialChar ~
=\SpecialChar ~
4000
\color default
 
\series bold 
\noun on 
(hal)
\series default 
\noun default 
 Specifies the number of pulses that corresponds to a move of one machine
 unit.
 For stepper systems, this is the number of step pulses issued per machine
 unit.
 For servo systems, this is the number of feedback pulses per machine unit.
 A second number, if specified, is ignored.
\color black

\newline 
For example, on a 1.8 degree stepper motor with half-stepping, and 10 revs/inch
 gearing, and desired units of mm, we have
\begin_inset Formula \begin{eqnarray*}
input\_ scale & = & \frac{{2\, steps}}{1.8\, degree}*360\frac{{degree}}{rev}*10\frac{rev}{inch}\\
 & = & 4000\frac{steps}{inch}\end{eqnarray*}

\end_inset 

Older stepper configuration .ini and .hal used INPUT_SCALE for this value.
\layout Description

STEPGEN_MAXACCEL\SpecialChar ~

\series bold 
=\SpecialChar ~
21.0
\series default 
 
\series bold 
\noun on 
(hal)
\series default 
\noun default 
 Acceleration limit for the step generator.
 This should be 1% to 10% larger than the axis MAX_ACCELERATION.
 This value improves the tuning of stepgen's 
\begin_inset Quotes eld
\end_inset 

position loop
\begin_inset Quotes erd
\end_inset 

.
\layout Description

STEPGEN_MAXVEL\SpecialChar ~

\series bold 
=
\series default 
\SpecialChar ~

\series bold 
1.4
\series default 
 
\series bold 
\noun on 
(hal)
\series default 
\noun default 
 Older configuration files have a velocity limit for the step generator
 as well.

\series bold 
 
\series default 
If specified, it should also be 1% to 10% larger than the axis MAX_VELOCITY.
 Subsequent testing has shown that use of STEPGEN_MAXVEL does not improve
 the tuning of stepgen's position loop.
 
\layout Subsection

[EMCIO] Section 
\begin_inset LatexCommand \label{sub:[EMCIO]-Section}

\end_inset 


\begin_inset LatexCommand \index{ini [EMCIO] Section}

\end_inset 


\layout Description

CYCLE_TIME\SpecialChar ~

\series bold 
=
\series default 
\SpecialChar ~

\series bold 
0.100
\series default 
 The period, in seconds, at which EMCIO will run.
 Making it 0.0 or a negative number will tell EMCIO not to sleep at all.
 There is usually no need to change this number.
\layout Description

TOOL_TABLE\SpecialChar ~

\series bold 
=
\series default 
\SpecialChar ~

\series bold 
tool.tbl
\series default 
 The file which contains tool information.
 For more information see the G Code Manual.
\layout Description

TOOL_CHANGE_POSITION\SpecialChar ~

\series bold 
=\SpecialChar ~
0\SpecialChar ~
0\SpecialChar ~
2
\series default 
 Specifies the XYZ location to move to when performing a tool change.
\the_end