Hi All;
I am attempting to configure EMC2 10.04.06 to control RPM
on a 60 HZ AC generator.
The basic approach is:
-Set the steps per inch to the number of AC cycles per day.
-Monitor the AC frequency into phase A of a HAL encoder.
-Feed the encoder output into the axis and PID feedback.
-Feed the axis motor-pos-cmd to stepgen position-cmd.
-Feed the stepgen out through the paraport to a stepper motor driver.
This seems to work in general but there are two problems I
have not been able to pin down.
1- The PID error is a sawtooth shape causing the throttle
stepper motor to quiver at 60 HZ.
A HAL Scope image is available at
http://imagebin.org/135986
Anyone have an idea how to correct this. The tighter i
make the PID loop the greater the quiver.
2- When the RPM (step rate) gets behind during start up
or load increase, EMC attempts to correct as soon as
allowed in .ini and PID acceleration settings.
Is there a way to limit this correction max RPM to avoid
excessive over speed?
A snippet of the .ini and .hal files follow.
The HAL Scope image is at http://imagebin.org/135986 for
14 days.
Thanks
Don
.ini snippet
----------------------------------------------------------------
[TRAJ]
AXES = 9
#COORDINATES = X Y Z A B C U V W Template for counting AXIS numbers
COORDINATES = X Y Z U
HOME = 0 0 0 0
NO_FORCE_HOMING = 1
LINEAR_UNITS = inch
ANGULAR_UNITS = degree
CYCLE_TIME = 0.010
DEFAULT_VELOCITY = 1.
MAX_VELOCITY = 1.
DEFAULT_ACCELERATION = 100.0
MAX_ACCELERATION = 20.0
#POSITION_FILE = position.txt
# First axis ---- (X) Generators Electrical Switching ??
-----------------------
[AXIS_0]
TYPE = LINEAR
HOME_SEQUENCE = 0
MAX_VELOCITY = 1.2
MAX_ACCELERATION = 20.0
STEPGEN_MAXACCEL = 21.0
BACKLASH = 0.0
SCALE = 4000
OUTPUT_SCALE = 1.000
MIN_LIMIT = -10.0
MAX_LIMIT = 10.0
FERROR = 0.050
MIN_FERROR = 0.010
DEADBAND = 0.000
# Second axis ---- (Y) Gen1 RPM Controll ---------------------------
[AXIS_1]
TYPE = LINEAR
HOME_SEQUENCE = 1
# 62 HZ Max (makeup rate)
MAX_VELOCITY = 0.00001195169045
# 60 HZ = .00001156615205
#MAX_ACCELERATION = 20.0
MAX_ACCELERATION = 1.
#STEPGEN_MAXACCEL = 21.0
#STEPGEN_MAXACCEL = .1
STEPGEN_MAXACCEL = 1.005
#PID_MAX_VEL = 1.25
#PID_MAX_VEL = 0.00001195169045
# 60 HZ for one Day (= one inch). Includes leap seconds
INPUT_SCALE = 5187550.687
#INPUT_SCALE = 10375101.37
#OUTPUT_SCALE = 5187550.687
OUTPUT_SCALE = 1.0
MIN_LIMIT = -0.0
# 14 Days (inches) = 336 Hours. **** OIL CHANGE & LUBE TIME ****
MAX_LIMIT = 14
FERROR = 1.5100
MIN_FERROR = 1.501
DEADBAND = 0.0
P = 200
I = 50
D = 1
BIAS = 0
FF0 = 0
FF1 = 0.4
FF2 = 0.0
.hal snippet ------------------------------------------------------------
# HAL config file for power1 (servo to stepper)
# first load the core RT modules that will be needed
loadrt trivkins
loadrt [EMCMOT]EMCMOT base_period_nsec=[EMCMOT]BASE_PERIOD
servo_period_nsec=[EMCMOT]SERVO_PERIOD num_joints=[TRAJ]AXES
#loadrt stepgen step_type=0,0,0,0 ctrl_type=p,v,v,v
loadrt stepgen step_type=0,0,0,0
loadrt pid num_chan=3
loadrt encoder num_chan=4
loadrt hal_parport cfg="0x0378"
# hook functions to base thread
addf parport.0.read base-thread 1
addf stepgen.make-pulses base-thread
addf encoder.update-counters base-thread
addf parport.0.write base-thread -1
# hook functions to servo thread
addf stepgen.capture-position servo-thread
addf encoder.capture-position servo-thread
addf motion-command-handler servo-thread
addf motion-controller servo-thread
addf pid.0.do-pid-calcs servo-thread
addf pid.1.do-pid-calcs servo-thread
addf pid.2.do-pid-calcs servo-thread
addf stepgen.update-freq servo-thread
# set values from .ini file for AXIS_0 - (X Electrical Switching ??)
setp stepgen.0.position-scale [AXIS_0]SCALE
setp stepgen.0.maxaccel [AXIS_0]STEPGEN_MAXACCEL
# connections for AXIS_0 - (X)
net Xen axis.0.amp-enable-out => stepgen.0.enable
net Xcmd axis.0.motor-pos-cmd => stepgen.0.position-cmd
net Xfb stepgen.0.position-fb => axis.0.motor-pos-fb
#net Xstep stepgen.0.step => parport.0.pin-03-out ------ borrowed for
Axis 1 below temp.
#net Xdir stepgen.0.dir => parport.0.pin-02-out
# set values from .ini file for AXIS_1 - (Y Gen1 RPM)
setp pid.0.maxerror 1.
setp pid.0.maxoutput 1.
setp pid.0.Pgain [AXIS_1]P
setp pid.0.Igain [AXIS_1]I
setp pid.0.Dgain [AXIS_1]D
setp pid.0.bias [AXIS_1]BIAS
setp pid.0.FF0 [AXIS_1]FF0
setp pid.0.FF1 [AXIS_1]FF1
setp pid.0.FF2 [AXIS_1]FF2
setp pid.0.deadband [AXIS_2]DEADBAND
setp encoder.1.counter-mode 1
setp encoder.1.position-scale [AXIS_1]INPUT_SCALE
setp stepgen.1.position-scale [AXIS_1]INPUT_SCALE
setp stepgen.1.maxaccel [AXIS_1]STEPGEN_MAXACCEL
# connections for AXIS_1 - (X)
net Yenabl axis.1.amp-enable-out => pid.0.enable => stepgen.1.enable
net Ycmd axis.1.motor-pos-cmd => pid.0.command
net YencAin encoder.1.phase-A <= parport.0.pin-10-in
net Yfb encoder.1.position => axis.1.motor-pos-fb => pid.0.feedback
net YRPMcmd pid.0.output => stepgen.1.position-cmd
#net Ystep stepgen.1.step => parport.0.pin-05-out
#net Ydir stepgen.1.dir => parport.0.pin-04-out
net Ystep stepgen.1.step => parport.0.pin-03-out
net Ydir stepgen.1.dir => parport.0.pin-02-out
------------------------------------------------------------------------------
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