New component at_pidv2 based on at_pid and pid components.

Started with a copy of pid.c, and copied relevant code from
at_pid.c and inserted it into relevant locations.  This way
at_pidv2 become compatible with the current pid component, and
those that want to test autotuning can insert it in-place
without modifying any pins and signals in their HAL files.

The original at_pid code was commited by Peter G. Vavaroutsos,
so insert his name as author and also copy the module name over.

Manual page at_pidv2(9) is based on pid(9) with the comment about
the auto-tuning code not being updated since 2011 added and the
relevant parts coped over from at_pid(9).

This module is tested and found to be giving not completely unusable
P, I and D values for horizontal movements.

Author: petterreinholdtsen

docs/man/man9/at_pidv2.9

@@ -6,6 +6,9 @@ pid \- proportional/integral/derivative controller
 \fBloadrt pid [num_chan=\fInum\fB | names=\fIname1\fB[,\fIname2...\fB]] [\fBdebug=\fIdbg\fR]
 
 .SH DESCRIPTION
+\fBNOTE:\fR The auto-tuning part of this component have seen
+no development since 2011.
+.P
 \fBpid\fR is a classic Proportional/Integral/Derivative controller,
 used to control position or speed feedback loops for servo motors and
 other closed-loop applications.
@@ -161,6 +164,29 @@ output = bias + error * Pgain + errorI * Igain +
 limit output to +/- maxoutput
 .fi
 
+.P
+This component has a built in auto tune mode. It works by setting up a limit
+cycle to characterize the process. From this, \fBPgain/Igain/Dgain\fR or
+\fBPgain/Igain/FF1\fR can be determined using Ziegler-Nichols. When using
+\fBFF1\fR, scaling must be set so that \fBoutput\fR is in user units per second.
+.P
+During auto tuning, the \fBcommand\fR input should not change. The limit
+cycle is setup around the commanded position. No initial tuning values are
+required to start auto tuning.  Only \fBtune\-cycles\fR, \fBtune\-effort\fR
+and \fBtune\-mode\fR need be set before starting auto tuning.  When auto tuning
+completes, the tuning parameters will be set. If running from LinuxCNC, the
+FERROR setting for the axis being tuned may need to be loosened up as it must
+be larger than the limit cycle amplitude in order to avoid a following error.
+.P
+To perform auto tuning, take the following steps.  Move the axis to be tuned,
+to somewhere near the center of it's travel.  Set \fBtune\-cycles\fR (the
+default value should be fine in most cases) and \fBtune\-mode\fR. Set
+\fBtune\-effort\fR to a small value. Set \fBenable\fR to true. Set
+\fBtune\-mode\fR to true. Set \fBtune\-start\fR to true. If no oscillation
+occurs, or the oscillation is too small, slowly increase \fBtune\-effort\fR.
+Auto tuning can be aborted at any time by setting \fBenable\fR or
+\fBtune\-mode\fR to false.
+
 .SH NAMING
 The names for pins, parameters, and functions are prefixed as:
   \fBpid.N.\fR for N=0,1,...,num\-1 when using \fBnum_chan=num\fR
@@ -339,6 +365,40 @@ When true, the current PID output is saturated.  That is,
 \fBpid.\fIN\fB.saturated\-count\fR s32 out
 When true, the output of PID was continually saturated for this many seconds
 (\fBsaturated\-s\fR) or periods (\fBsaturated\-count\fR).
+
+.SS Additional auto tuning pins
+.TP
+\fBpid.\fIN\fB.tune\-mode\fR bit in
+When true, enables auto tune mode.  When false, normal PID calculations are
+performed.
+.TP
+\fBpid.\fIN\fB.tune\-start\fR bit io
+When set to true, starts auto tuning.  Cleared when the auto tuning completes.
+.TP
+\fBpid.\fIN\fB.tune\-type\fR u32 rw
+When set to 0, \fBPgain/Igain/Dgain\fR are calculated. When set to 1,
+\fBPgain/Igain/FF1\fR are calculated.
+.TP
+\fBpid.\fIN\fB.tune\-cycles\fR u32 rw
+Determines the number of cycles to run to characterize the process.
+\fBtune\-cycles\fR actually sets the number of half cycles. More cycles results
+in a more accurate characterization as the average of all cycles is used.
+.TP
+\fBpid.\fIN\fB.tune\-effort\fR float rw
+Determines the effort used in setting up the limit cycle in the process.
+\fBtune\-effort\fR should be set to a positive value less than \fBmaxoutput\fR.
+Start with something small and work up to a value that results in a good
+portion of the maximum motor current being used. The smaller the value, the
+smaller the amplitude of the limit cycle.
+.TP
+\fBpid.\fIN\fB.ultimate\-gain\fR float ro (only if debug=1)
+Determined from process characterization. \fBultimate\-gain\fR is the ratio of
+\fBtune\-effort\fR to the limit cycle amplitude multiplied by 4.0 divided by Pi.
+.TP
+\fBpid.\fIN\fB.ultimate\-period\fR float ro (only if debug=1)
+Determined from process characterization. \fBultimate\-period\fR is the period
+of the limit cycle.
+
 .SH PARAMETERS
 .TP
 \fBpid.\fIN\fB.errorI\fR float ro (only if debug=1)
@@ -373,4 +433,4 @@ gains to fix it is a mistake; set the scaling correctly elsewhere
 instead.
 
 .SH SEE ALSO
-\fBat_pid\fR(9)
+\fBpid\fR(9)

src/Makefile

@@ -894,6 +894,8 @@ obj-$(CONFIG_PID) += pid.o
 pid-objs := hal/components/pid.o $(MATHSTUB)
 obj-$(CONFIG_AT_PID) += at_pid.o
 at_pid-objs := hal/components/at_pid.o $(MATHSTUB)
+obj-$(CONFIG_AT_PIDV2) += at_pidv2.o
+at_pidv2-objs := hal/components/at_pidv2.o $(MATHSTUB)
 obj-$(CONFIG_PID) += threads.o
 threads-objs := hal/components/threads.o $(MATHSTUB)
 obj-$(CONFIG_SUPPLY) += supply.o
@@ -1226,6 +1228,7 @@ endif
 ../rtlib/pwmgen$(MODULE_EXT): $(addprefix objects/rt,$(pwmgen-objs))
 ../rtlib/siggen$(MODULE_EXT): $(addprefix objects/rt,$(siggen-objs))
 ../rtlib/at_pid$(MODULE_EXT): $(addprefix objects/rt,$(at_pid-objs))
+../rtlib/at_pidv2$(MODULE_EXT): $(addprefix objects/rt,$(at_pidv2-objs))
 ../rtlib/pid$(MODULE_EXT): $(addprefix objects/rt,$(pid-objs))
 ../rtlib/threads$(MODULE_EXT): $(addprefix objects/rt,$(threads-objs))
 ../rtlib/supply$(MODULE_EXT): $(addprefix objects/rt,$(supply-objs))

src/Makefile.inc.in

@@ -190,6 +190,7 @@ CONFIG_FREQGEN=m
 CONFIG_PWMGEN=m
 CONFIG_SIGGEN=m
 CONFIG_AT_PID=m
+CONFIG_AT_PIDV2=m
 CONFIG_PID=m
 CONFIG_SUPPLY=m
 CONFIG_CLASSICLADDER_RT=m