rtcomps.lyx

CNC 的开放码,EMC2 V2.2.8版

dirdelay
\family default 
 are all rounded up to a integer multiple of the thread periond in nanoseconds.
 The other two functions can be called at a much lower rate.
\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Section


\begin_inset LatexCommand \label{sec:PWMgen}

\end_inset 

PWMgen
\begin_inset LatexCommand \index{pwmgen}

\end_inset 


\layout Standard

This component provides software based generation of PWM (Pulse Width Modulation
) and PDM (Pulse Density Modulation) waveforms.
 It is a realtime component only, and depending on CPU speed, etc, is capable
 of PWM frequencies from a few hundred Hertz at pretty good resolution,
 to perhaps 10KHz with limited resolution.
\layout Subsection

Installing
\layout LyX-Code

emc2$ 
\series bold 
halcmd loadrt pwmgen output_type=<config-array>
\layout Standard


\family typewriter 
<config-array>
\family default 
 is a series of comma separated decimal integers.
 Each number causes a single PWM generator to be loaded, the value of the
 number determines the output type.
 For example:
\layout LyX-Code

emc2$ 
\series bold 
halcmd loadrt pwmgen step_type=0,1,2
\layout Standard

will install three PWM generators.
 The first one will use output type '0' (PWM only), the next uses output
 type 1 (PWM and direction) and the last one uses output type 2 (UP and
 DOWN).
 There is no default value, if 
\family typewriter 
<config-array>
\family default 
 is not specified, no PWM generators will be installed.
 The maximum number of frequency generators is 8 (as defined by MAX_CHAN
 in pwmgen.c).
 Each generator is independent, but all are updated by the same function(s)
 at the same time.
 In the following descriptions, 
\family typewriter 
<chan>
\family default 
 is the number of a specific generator.
 The first generator is number 0.
\layout Subsection

Removing
\layout LyX-Code

emc2$ 
\series bold 
halcmd unloadrt pwmgen
\layout Subsection

Pins
\layout Standard

Each PWM generator will have the following pins:
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pwmgen.<chan>.value
\family default 
 -- Command value, in arbitrary units.
 Will be scaled by the 
\family typewriter 
scale
\family default 
 parameter (see below).
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 pwmgen.<chan>.enable
\family default 
 -- Enables or disables the PWM generator outputs.
\layout Standard

Each PWM generator will also have some of these pins, depending on the output
 type selected:
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 pwmgen.<chan>.pwm
\family default 
 -- PWM (or PDM) output, (output types 0 and 1 only).
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 pwmgen.<chan>.dir
\family default 
 -- Direction output (output type 1 only).
\layout Itemize


\family typewriter 
\noun on 
(bit) 
\noun default 
pwmgen.<chan>.up
\family default 
 -- PWM/PDM output for positive input value (output type 2 only).
\layout Itemize


\family typewriter 
\noun on 
(bit) 
\noun default 
pwmgen.<chan>.down
\family default 
 -- PWM/PDM output for negative input value (output type 2 only).
\layout Subsection

Parameters
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pwmgen.<chan>.scale
\family default 
 -- Scaling factor to convert 
\family typewriter 
value
\family default 
 from arbitrary units to duty cycle.
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pwmgen.<chan>.pwm-freq
\family default 
 -- Desired PWM frequency, in Hz.
 If 0.0, generates PDM instead of PWM.
 If set higher than internal limits, next call of 
\family typewriter 
update_freq()
\family default 
 will set it to the internal limit.
 If non-zero, and 
\family typewriter 
dither
\family default 
 is false, next call of 
\family typewriter 
update_freq()
\family default 
 will set it to the nearest integer multiple of the 
\family typewriter 
make_pulses()
\family default 
 function period.
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 pwmgen.<chan>.dither-pwm
\family default 
 -- If true, enables dithering to achieve average PWM frequencies or duty
 cycles that are unobtainable with pure PWM.
 If false, both the PWM frequency and the duty cycle will be rounded to
 values that can be achieved exactly.
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pwmgen.<chan>.min-dc
\family default 
 -- Minimum duty cycle, between 0.0 and 1.0 (duty cycle will go to zero when
 disabled, regardless of this setting).
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pwmgen.<chan>.max-dc
\family default 
 -- Maximum duty cycle, between 0.0 and 1.0.
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pwmgen.<chan>.curr-dc
\family default 
 -- Current duty cycle - after all limiting and rounding (read only).
\layout Subsection

Output Types
\layout Standard

The PWM generator supports three different 
\begin_inset Quotes eld
\end_inset 

output types
\begin_inset Quotes erd
\end_inset 

.
 Type 0 has a single output pin.
 Only positive commands are accepted, negative values are treated as zero
 (and will be affected by
\family typewriter 
 min-dc
\family default 
 if it is non-zero).
 Type 1 has two output pins, one for the PWM/PDM signal and one to indicate
 direction.
 The duty cycle on the PWM pin is based on the absolute value of the command,
 so negative values are acceptable.
 The direction pin is false for positive commands, and true for negative
 commands.
 Finally, type 2 also has two outputs, called up and down.
 For positive commands, the PWM signal appears on the up output, and the
 down output remains false.
 For negative commands, the PWM signal appears on the down output, and the
 up output remains false.
 Output type 2 is suitable for driving most H-bridges.
\layout Subsection

Functions
\layout Standard

The component exports two functions.
 Each function acts on all of the PWM generators - running different generators
 in different threads is not supported.
 
\layout Itemize


\family typewriter 
\noun on 
(funct)
\noun default 
 pwmgen.make-pulses
\family default 
 -- High speed function to generate PWM waveforms (no floating point).
\layout Itemize


\family typewriter 
\noun on 
(funct)
\noun default 
 pwmgen.update
\family default 
 -- Low speed function to scale and limit value and handle other paremeters.
\layout Standard

The high speed function 
\family typewriter 
pwmgen.make-pulses
\family default 
 should be run in a very fast thread, from 10 to 50uS depending on the capabilit
ies of the computer.
 That thread's period determines the maximum PWM carrier frequency, as well
 as the resolution of the PWM or PDM signals.
 The other function can be called at a much lower rate.
\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Section


\begin_inset LatexCommand \label{sec:Encoder}

\end_inset 

Encoder
\begin_inset LatexCommand \index{encoder}

\end_inset 


\layout Standard

This component provides software based counting of signals from quadrature
 encoders.
 It is a realtime component only, and depending on CPU speed, etc, is capable
 of maximum count rates of 10kHz to perhaps 50kHz.
 Figure 
\begin_inset LatexCommand \ref{fig:Encoder-Block-Diag}

\end_inset 

 is a block diagram of one channel of encoder counter.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename encoder-block-diag.eps
	width 7in
	height 6in
	keepAspectRatio

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:Encoder-Block-Diag}

\end_inset 

Encoder Counter Block Diagram
\end_inset 


\layout Subsection

Installing
\layout LyX-Code

emc2$ 
\series bold 
halcmd loadrt encoder [num_chan=<counters>]
\layout Standard


\family typewriter 
<counters>
\family default 
 is the number of encoder counters that you want to install.
 If 
\family typewriter 
numchan
\family default 
 is not specified, three counters will be installed.
 The maximum number of counters is 8 (as defined by MAX_CHAN in encoder.c).
 Each counter is independent, but all are updated by the same function(s)
 at the same time.
 In the following descriptions, 
\family typewriter 
<chan>
\family default 
 is the number of a specific counter.
 The first counter is number 0.
\layout Subsection

Removing
\layout LyX-Code

emc2$ 
\series bold 
halcmd unloadrt encoder
\layout Subsection

Pins
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 encoder.<chan>.phase-A
\family default 
 -- Phase A of the quadrature encoder signal.
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 encoder.<chan>.phase-B
\family default 
 -- Phase B of the quadrature encoder signal.
\layout Itemize


\family typewriter 
\noun on 
(bit)
\noun default 
 encoder.<chan>.phase-Z
\family default 
 -- Phase Z (index pulse) of the quadrature encoder signal.
\layout Itemize


\family typewriter 
\noun on 
(bit) 
\noun default 
encoder.<chan>.reset
\family default 
 -- See canonical encoder interface, section 
\begin_inset LatexCommand \ref{sec:CanonEncoder}

\end_inset 

.
\layout Itemize


\family typewriter 
\noun on 
(bit) 
\noun default 
encoder.<chan>.velocity
\family default 
 -- Estimated speed of the quadrature signal.
 
\layout Itemize


\family typewriter 
\noun on 
(bit) 
\noun default 
encoder.<chan>.index-enable
\family default 
 -- See canonical encoder interface.
\layout Itemize


\family typewriter 
\noun on 
(s32) 
\noun default 
encoder.<chan>.count
\family default 
 -- See canonical encoder interface.
\layout Itemize


\family typewriter 
\noun on 
(float) 
\noun default 
encoder.<chan>.position
\family default 
 -- See canonical encoder interface.
\layout Subsection

Parameters
\layout Itemize


\family typewriter 
\noun on 
(s32)
\noun default 
 encoder.<chan>.raw-count
\family default 
 -- The raw count value, updated by 
\family typewriter 
update-counters()
\family default 
.
 
\layout Itemize


\family typewriter 
(
\noun on 
bit
\noun default 
) encoder.<chan>.x4-mode
\family default 
 -- Sets encoder to 4x or 1x mode.
 The 1x mode is usefull for some jogwheels.
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 encoder.<chan>.position-scale
\family default 
 -- See canonical encoder interface, section 
\begin_inset LatexCommand \ref{sec:CanonEncoder}

\end_inset 

.
 
\layout Subsection

Functions
\layout Standard

The component exports two functions.
 Each function acts on all of the encoder counters - running different counters
 in different threads is not supported.
 
\layout Itemize


\family typewriter 
\noun on 
(funct)
\noun default 
 encoder.update-counters
\family default 
 -- High speed function to count pulses (no floating point).
\layout Itemize


\family typewriter 
\noun on 
(funct)
\noun default 
 encoder.capture-position
\family default 
 -- Low speed function to update latches and scale position.
\layout Standard


\begin_inset ERT
status Collapsed

\layout Standard

\backslash 
clearpage
\end_inset 


\layout Section


\begin_inset LatexCommand \label{sec:PID}

\end_inset 

PID
\begin_inset LatexCommand \index{pid}

\end_inset 


\layout Standard

This component provides Proportional/Integeral/Derivative control loops.
 It is a realtime component only.
 For simplicity, this discussion assumes that we are talking about position
 loops, however this component can be used to implement other feedback loops
 such as speed, torch height, temperature, etc.
 Figure 
\begin_inset LatexCommand \ref{fig:PID-block-diag}

\end_inset 

 is a block diagram of a single PID loop.
\layout Standard


\begin_inset Float figure
wide false
collapsed false

\layout Standard
\align center 

\begin_inset Graphics
	filename pid-block-diag.eps
	width 8in
	height 10in
	keepAspectRatio
	rotateAngle 90
	rotateOrigin center

\end_inset 


\layout Caption


\begin_inset LatexCommand \label{fig:PID-block-diag}

\end_inset 

PID Loop Block Diagram
\end_inset 


\layout Subsection

Installing
\layout LyX-Code

emc2$ 
\series bold 
halcmd loadrt pid [num_chan=<loops>] [debug=1]
\layout Standard


\family typewriter 
<loops>
\family default 
 is the number of PID loops that you want to install.
 If 
\family typewriter 
numchan
\family default 
 is not specified, one loop will be installed.
 The maximum number of loops is 16 (as defined by MAX_CHAN in pid.c).
 Each loop is completely independent.
 In the following descriptions, 
\family typewriter 
<loopnum>
\family default 
 is the loop number of a specific loop.
 The first loop is number 0.
\layout Standard

If 
\family typewriter 
debug=1
\family default 
 is specified, the component will export a few extra parameters that may
 be useful during debugging and tuning.
 By default, the extra parameters are not exported, to save shared memory
 space and avoid cluttering the parameter list.
\layout Subsection

Removing
\layout LyX-Code

emc2$ 
\series bold 
halcmd unloadrt pid
\layout Subsection

Pins
\layout Standard

The three most important pins are 
\layout Itemize


\family typewriter 
\noun on 
(float) 
\noun default 
pid.<loopnum>.command
\family default 
 -- The desired position, as commanded by another system component.
\layout Itemize


\family typewriter 
\noun on 
(float) 
\noun default 
pid.<loopnum>.feedback
\family default 
 -- The present position, as measured by a feedback device such as an encoder.
\layout Itemize


\family typewriter 
\noun on 
(float) 
\noun default 
pid.<loopnum>.output
\family default 
 -- A velocity command that attempts to move from the present position to
 the desired position.
 
\layout Standard

For a position loop, 'command' and 'feedback' are in position units.
 For a linear axis, this could be inches, mm, meters, or whatever is relevant.
 Likewise, for an angular axis, it could be degrees, radians, etc.
 The units of the 'output' pin represent the change needed to make the feedback
 match the command.
 As such, for a position loop 'Output' is a velocity, in inches/sec, mm/sec,
 degrees/sec, etc.
 Time units are always seconds, and the velocity units match the position
 units.
 If command and feedback are in meters, then output is in meters per second.
 
\layout Standard

Each loop has two other pins which are used to monitor or control the general
 operation of the component.
 
\layout Itemize


\family typewriter 
\noun on 
(float) 
\noun default 
pid.<loopnum>.error
\family default 
 -- Equals 
\family typewriter 
.command
\family default 
 minus 
\family typewriter 
.feedback
\family default 
.
\layout Itemize


\family typewriter 
\noun on 
(bit) 
\noun default 
pid.<loopnum>.enable
\family default 
 -- A bit that enables the loop.
 If 
\family typewriter 
.enable
\family default 
 is false, all integrators are reset, and the output is forced to zero.
 If 
\family typewriter 
.enable
\family default 
 is true, the loop operates normally.
\layout Subsection

Parameters
\layout Standard

The PID gains, limits, and other 'tunable' features of the loop are implemented
 as parameters.
 
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pid.<loopnum>.Pgain
\family default 
 -- Proportional gain 
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pid.<loopnum>.Igain
\family default 
 -- Integral gain 
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pid.<loopnum>.Dgain
\family default 
 -- Derivative gain 
\layout Itemize


\family typewriter 
\noun on 
(float)
\noun default 
 pid.<loopnum>.bias
\family default 
 -- Constant offset on output 
\layout Itemize