Are the amps manufactured by Westamp?


Dave B

On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:

Are the amps manufactured by Westamp?


Dave B


I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

On Dec 29, 4:11*pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

Dave;

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. The problem is with the base settings the servos are vibrating
like crazy. Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

top posted to annoy those who hate top posting

if the servo is vibrating, it is unstable. You can do a root locus plot,
or you can fake it
the most likely cause is lag in the feedback system - you can accommodate
additional lag by reducing the forward path gain (that's what your gain pot
is for) - you might try playing with the TAC input, you may not have enough
rate feedback - it sounds like your servo has an inner rate loop and an
outer position loop, so the rate is primarily responsible for damping and
responsiveness, and the position loop gets you where you want to go.

Just a little reading on feedback systems will go a long way towards giving
you some understanding of what is going on.

Given that this happened when you changed the position sensor, I am guessing
that it is a phase lag type phenomena because the new sensor is slower
(maybe only by a few milliseconds) than the old one. Digital sensors
introduce pure lag which is the worst thing for a standard feedback control
system.





"oldjag" wrote in message
...
On Dec 29, 4:11 pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

Dave;

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. The problem is with the base settings the servos are vibrating
like crazy. Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. Vendor thinks maybe
problem is the new encoders, but I'm not convinced.


** Posted from http://www.teranews.com **

On Tue, 30 Dec 2008 20:29:14 -0800 (PST), oldjag
wrote:


The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. The problem is with the base settings the servos are vibrating
like crazy. Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

Presumably the encoders connect to the motion (CNC) controller. You've
changed the encoder resolution, so to get best performance you need to
change the gains in the PID loop in the controller. As you've found,
fussing with the amp's gain will stabilize the loop at the expense of
performance, but I don't think you'll be able to get the stiffness
back without tuning the PID loop in the controller. Do you have
access to the proportional, integral, and derivative gains in the
controller?

--
Ned Simmons

On Tue, 30 Dec 2008 22:44:17 -0800, "Bill Noble"
wrote:

top posted to annoy those who hate top posting

if the servo is vibrating, it is unstable. You can do a root locus plot,
or you can fake it
the most likely cause is lag in the feedback system - you can accommodate
additional lag by reducing the forward path gain (that's what your gain pot
is for) - you might try playing with the TAC input, you may not have enough
rate feedback - it sounds like your servo has an inner rate loop and an
outer position loop, so the rate is primarily responsible for damping and
responsiveness, and the position loop gets you where you want to go.

Just a little reading on feedback systems will go a long way towards giving
you some understanding of what is going on.

Given that this happened when you changed the position sensor, I am guessing
that it is a phase lag type phenomena because the new sensor is slower
(maybe only by a few milliseconds) than the old one. Digital sensors
introduce pure lag which is the worst thing for a standard feedback control
system.





"oldjag" wrote in message
...
On Dec 29, 4:11 pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

Dave;

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. The problem is with the base settings the servos are vibrating
like crazy. Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. Vendor thinks maybe
problem is the new encoders, but I'm not convinced.


** Posted from http://www.teranews.com **


I tend to agree with the vendor, I looked all over the net for some
information on the MPU unit you replaced and didn't find much.
The symptons are related to a resoultion problem, however the fact the
move amount is correct confuses the issues.

Would be nice to get in an open loop condition and run only the
velocity loop from a battery box. If the D/A puts out 9-10 volts at
max then you could use a battery box and put lets say a 1 volt speed
command and monitor the tach to ensure the scaling is correct for
proper speed.

If the rapid rate is 200 ipm and the tach is 3 volts per 1000 rpm
(screw) or whatever you could at least determine how close you are.

Once this is correct in your mind then you know the problem is in the
position loop.

If you disable the servo and command a rapid move what is the output
voltage to the drive?

Regards

Dave B

What do you mean with the term A/D as "A/D signal" and "A/D voltage"? You
sound, from context, as though the term D/A would be appropriate.
On another angle, you might look for a y in the path from the encoders;
one pathway to the displays and another to the control boards. Possibly
the pathway to the controller has it's own adjustments to accomodate
the change.

Hul


oldjag wrote:
On Dec 29, 4:11?pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

Dave;

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. The problem is with the base settings the servos are vibrating
like crazy. Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

On Jan 1, 1:54*pm, Dave B wrote:
On Tue, 30 Dec 2008 22:44:17 -0800, "Bill Noble"
wrote:



top posted to annoy those who hate top posting

if the servo is vibrating, it is unstable. *You can do a root locus plot,
or you can fake it
the most likely cause is lag in the feedback system - you can accommodate
additional lag by reducing the forward path gain (that's what your gain pot
is for) - you might try playing with the TAC input, you may not have enough
rate feedback - it sounds like your servo has an inner rate loop and an
outer position loop, so the rate is primarily responsible for damping and
responsiveness, and the position loop gets you where you want to go.

Just a little reading on feedback systems will go a long way towards giving
you some understanding of what is going on.

Given that this happened when you changed the position sensor, I am guessing
that it is a phase lag type phenomena because the new sensor is slower
(maybe only by a few milliseconds) than the old one. *Digital sensors
introduce pure lag which is the worst thing for a standard feedback control
system.

"oldjag" wrote in message
....
On Dec 29, 4:11 pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

Dave;

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. *Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. *The problem is with the base settings the servos are vibrating
like crazy. *Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. *Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. *Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

** Posted fromhttp://www.teranews.com**

I tend to agree with the vendor, I looked all over the net for some
information on the MPU unit you replaced and didn't find much.
The symptons are related to a resoultion problem, however the fact the
move amount is correct confuses the issues.

Would be nice to get in an open loop condition and run only the
velocity loop from a battery box. If the D/A puts out 9-10 volts at
max then you could use a battery box and put lets say a 1 volt speed
command and monitor the tach to ensure the scaling is correct for
proper speed.

If the rapid rate is 200 ipm and the tach is 3 volts per 1000 rpm
(screw) or whatever you could at least determine how close you are.

Once this is correct in your mind then you know the problem is in the
position loop.

If you disable the servo and command a rapid move what is the output
voltage to the drive?

Regards

Dave B

Dave;

I separated the A/D, (analog output), from the Servo control board
that goes to the Servo amp input. I see +/- 0.45 volts max when I
generate a position error by moving the servo motor shaft by hand back
and forth, the same min./max as with the Amps connected. There is
only a 1 count deadband between a reading of +0.45 volts and -0.45
volts. I have a dual channel scope monitoring the encoder inputs and
the Servo control board output. Inputting a rapid move or a very
small move makes no difference, ie I instantly get the same 0.45 volts
max either way. This is well below the specified 0.65-0.80vdc @ 20
IPM the tuning specs call for. I have probably had power on and off
to this thing a 100 times, and once in a while, say every 10 startups,
I get either no A/D output or I get 1.75vdc., rebooting the MPU board
returns the A/D to the +/- 0.45 scenario. The first time this
occurred I thought a probe got miss-placed, but it has happened enough
times now that I know that is not the case. So now it seems I have an
intermittent problem, possibly related to or in addition to the tuning
problem. When the 1.75 vdc happens, it seems real, ie. it goes +/- as
error is dialed in, or if I move the motor. I have a signal generator
which I could hookup to feed a fake varying A/D to the Servo amp to
check it out somewhat. Should a control A/D output from a control
board be normally be proportional to the position error?

On Jan 1, 6:28*pm, wrote:
What do you mean with the term A/D as "A/D signal" and "A/D voltage"? You
sound, from context, as though the term D/A would be appropriate.
On another angle, you might look for a y in the path from the encoders;
one pathway to the displays and another to the control boards. Possibly
the pathway to the controller has it's own adjustments to accomodate
the change.

Hul

oldjag wrote:
On Dec 29, 4:11?pm, Dave B wrote:
On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B
Dave;
The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. *Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. *The problem is with the base settings the servos are vibrating
like crazy. *Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. *Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.
At this point I'm not sure what to check next. *Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

Yeah, sorry I mean D/A output from the Servo control card. The
backlash comp. is still set to the same values as before the board
upgrade when everything was working. The backlash is set on the
interface board on this machine. I also set the backlash comps to zero
with not change in the vibration issue.

On Dec 31 2008, 1:44*am, "Bill Noble" wrote:
top posted to annoy those who hate top posting

*if the servo is vibrating, it is unstable. *You can do a root locus plot,
or you can fake it
the most likely cause is lag in the feedback system - you can accommodate
additional lag by reducing the forward path gain (that's what your gain pot
is for) - you might try playing with the TAC input, you may not have enough
rate feedback - it sounds like your servo has an inner rate loop and an
outer position loop, so the rate is primarily responsible for damping and
responsiveness, and the position loop gets you where you want to go.

Just a little reading on feedback systems will go a long way towards giving
you some understanding of what is going on.

Given that this happened when you changed the position sensor, I am guessing
that it is a phase lag type phenomena because the new sensor is slower
(maybe only by a few milliseconds) than the old one. *Digital sensors
introduce pure lag which is the worst thing for a standard feedback control
system.

"oldjag" wrote in message

...
On Dec 29, 4:11 pm, Dave B wrote:

On Mon, 29 Dec 2008 12:50:25 -0800, Dave B wrote:
Are the amps manufactured by Westamp?

Dave B

I have never worked on a Hurco, however it would seem there would be
parameters that allow you to alter the position loop gain.

Do you have parameters for backlash etc ?

Dave B

Dave;

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. *Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. *The problem is with the base settings the servos are vibrating
like crazy. *Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. *Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. *Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

** Posted fromhttp://www.teranews.com**

Bill;

TAC does not have much effect. With a dual trace scope I measured the
delay time from an encoder pulse input state change to the Servo
control board output changing state, and it's 9.6 millisec, which
seems a bit long. The new encoders are good for 100Khz, or 6000 rpm,
much faster than this machine can go. I measured the encoder rise
time at less than 0.4 micro seconds. By the way this "oscillation"
problem I am having begins as a "ticking" noise that occurs several
seconds apart, and increases in intensity and frequency off occurance
as the SIG pot is increased.

Each "Tick" is preceded by a gradual motor rotation of about 1/8 turn
and then a "snap" back to starting position, which makes the ticking
noise. All axis are doing the same thing, but for testing I've
disconnected all except the Z axis for now. I thinking about trying
an open loop run with a signal generator feeding the servo amp a slow
sine wave, say to start maybe 0.2 Hz. and increasing the frequency
from there. just to verify correct amp operation on the velocity
loop. The tach signal looks okay at the amp input.

Now I have noticed another issue, every so many bootups of the MPU,
instead of getting +0.45/-0.45 Vdc D/A output from the servo board it
gives +1.75/-1.75vdc on encoder state change. On some boots I get
nothing...nada. Maybe this is related, maybe not but it's very
weird. I double checked my connections when this happened, checked
the encoder inputs, and everything else was normal. Even the 0.45vdc
output is suspect, as the D/A is supposed to put out at least 0.65 -
0.8vdc at 20 IPM feed. This aspect seems like a board issue, but the
boards were sent back last week to the vendor and they checked out
okay on their test rig....

On Dec 31 2008, 1:10*pm, Ned Simmons wrote:
On Tue, 30 Dec 2008 20:29:14 -0800 (PST), oldjag



wrote:

The amps are Servomate Randtronics. They have the following Pot
adjustments: GAN = Gain, TAC = tachometer input, AUX=auxillary, (not
used), BAL=Balance, SIG=Signal and CLM=current limit. *Standard
preliminary setup is to MAX out, (20 turns CW) the CLM and the TAC,
set the BAL in the middle, adjust SIG to get the A/D out from the
servo control board to the Servo amps around 0.65V during a 20 in/min
feed, and use the BAL to get the voltage the sam in both directions.
Also the gain gets adjusted up to instability and backed off a few
turns. *The problem is with the base settings the servos are vibrating
like crazy. *Backing off the Sig kills the vibration, but with the sig
backed off to where the vibration stops, the servos are very slow to
respond, and the A/D voltage gets to only .45 volts. *Things checked
so far:
1.)Tach inputs to servo amp are okay and correct polarity.
2.)Encoder pulses look good on A, B and Z channels on scope at the
servo control board.
3.)Backlash on the ballscrews is less than 0.0002"
4.)Main cap on servo amp 80Vdc supply checks out okay.
5.) +12V and -12V Servo amp supply looks good.
6.) Position display is reading in the correct direction and is
accurate.
7.) A/D signal from servo amp looks noisy, but I don't know what
normal looks like.

At this point I'm not sure what to check next. *Vendor thinks maybe
problem is the new encoders, but I'm not convinced.

Presumably the encoders connect to the motion (CNC) controller. You've
changed the encoder resolution, so to get best performance you need to
change the gains in the PID loop in the controller. As you've found,
fussing with the amp's gain will stabilize the loop at the expense of
performance, but I don't think you'll be able to get the stiffness
back without tuning the PID loop in the controller. *Do you have
access to the proportional, integral, and derivative gains in the
controller?

--
Ned Simmons

Ned;

There are no pots for Prop, Integral, or Derivative on these amps.

On Thu, 1 Jan 2009 21:57:04 -0800 (PST), oldjag
wrote:

On Dec 31 2008, 1:10*pm, Ned Simmons wrote:
On Tue, 30 Dec 2008 20:29:14 -0800 (PST), oldjag

*Do you have
access to the proportional, integral, and derivative gains in the
controller?

--
Ned Simmons

Ned;

There are no pots for Prop, Integral, or Derivative on these amps.

Not on the amp, but in the controller itself, i.e., the device that's
generating the command signal. I don't know how old your machine is,
but for most any motion controller designed in the last 20 years or
so, the PID gains will be set in software. Adjusting the gain on the
amp has the effect of tweaking all the PID gains simultaneously by a
common multiplier, which I'm not convinced is what you want to do when
changing encoder resolution.

--
Ned Simmons

Following your doubt Ned, perhaps a couple of ttl decimal dividers
soldered to a prepoked pc board to divide both the quadrature signals
by 5 might work. The ease with which such a board is conceived and
probably to make might indicate such a creature already exists on the
market. Might be worth a look.

Hul

Not on the amp, but in the controller itself, i.e., the device that's
generating the command signal. I don't know how old your machine is,
but for most any motion controller designed in the last 20 years or
so, the PID gains will be set in software. Adjusting the gain on the
amp has the effect of tweaking all the PID gains simultaneously by a
common multiplier, which I'm not convinced is what you want to do when
changing encoder resolution.

--
Ned Simmons

After another minutes thought, decimal up/down counters (dividers) and
some logic to determine direction would be required. Hopefully though,
still worth a look.

Hul

wrote:
Following your doubt Ned, perhaps a couple of ttl decimal dividers
soldered to a prepoked pc board to divide both the quadrature signals
by 5 might work. The ease with which such a board is conceived and
probably to make might indicate such a creature already exists on the
market. Might be worth a look.

Hul

Not on the amp, but in the controller itself, i.e., the device that's
generating the command signal. I don't know how old your machine is,
but for most any motion controller designed in the last 20 years or
so, the PID gains will be set in software. Adjusting the gain on the
amp has the effect of tweaking all the PID gains simultaneously by a
common multiplier, which I'm not convinced is what you want to do when
changing encoder resolution.

--
Ned Simmons

Well it seems the weird boot to boot and day to day variation I was
seeing in the D/A output signal was a flaky 15+ power supply that
feeds the servo control board in the card rack. It would power up
okay to 15v, but then after a short period of time it's output voltage
would drop down to 3.5 volts. On some starts it would hold up okay
for a while, (that's when I was seeing the 1.75 vdc DA output). The
old TO-5 can regulator for this 1.5 amp 15vdc supply was shot. I made
a new supply from a 1.5 amp LM317T adjustable regulator, (2 bucks at
Radio Shack), installed it and now the Servos tune up rock steady.
The vibration or ticking on all of the axis is gone.

One clue there was a PS issue was that as I tried to adjust the SIG
pots up, I had to keep moving the BAL pot further and further from
center to get a balanced D/A voltage in both directions from the Servo
board.
The only issue now is getting the machine to home correctly. This may
be an related to getting the marker or index pulse in the correct
location relative to the end of travel limit switches.

Thanks for all of the feedback and comments.

Congratulations - Hul


oldjag wrote:
Well it seems the weird boot to boot and day to day variation I was
seeing in the D/A output signal was a flaky 15+ power supply that
feeds the servo control board in the card rack. It would power up
okay to 15v, but then after a short period of time it's output voltage
would drop down to 3.5 volts. On some starts it would hold up okay
for a while, (that's when I was seeing the 1.75 vdc DA output). The
old TO-5 can regulator for this 1.5 amp 15vdc supply was shot. I made
a new supply from a 1.5 amp LM317T adjustable regulator, (2 bucks at
Radio Shack), installed it and now the Servos tune up rock steady.
The vibration or ticking on all of the axis is gone.

One clue there was a PS issue was that as I tried to adjust the SIG
pots up, I had to keep moving the BAL pot further and further from
center to get a balanced D/A voltage in both directions from the Servo
board.
The only issue now is getting the machine to home correctly. This may
be an related to getting the marker or index pulse in the correct
location relative to the end of travel limit switches.

Thanks for all of the feedback and comments.

On Jan 4, 11:57*am, wrote:
Congratulations - Hul

wrote:
Well it seems the weird boot to boot and day to day variation I was
seeing in the D/A output signal was a flaky 15+ power supply that
feeds the servo control board in the card rack. *It would power up
okay to 15v, but then after a short period of time it's output voltage
would drop down to 3.5 volts. *On some starts it would hold up okay
for a while, (that's when I was seeing the 1.75 vdc DA output). The
old TO-5 can regulator for this 1.5 amp 15vdc supply was shot. *I made
a new supply from a 1.5 amp LM317T adjustable regulator, (2 bucks at
Radio Shack), installed it and now the Servos tune up rock steady.
The vibration or ticking on all of the axis is gone.
One clue there was a PS issue was that as I tried to adjust the SIG
pots up, I had to keep moving the BAL pot further and further from
center to get a balanced D/A voltage in both directions from the Servo
board.
The only issue now is getting the machine to home correctly. *This may
be an related to getting the marker or index pulse in the correct
location relative to the end of travel limit switches.
Thanks for all of the feedback and comments.

One last point, Kudos to Buddy at AMTS, he mentioned checking the plus
& minus 15V supplies for the Servo Board when I told him the symptoms.
I had checked all of the Supplies earlier, (there are 13 DC supplies
in this machine), and when checked, it must have been on it's best
behavior.

oldjag wrote:

One last point, Kudos to Buddy at AMTS, he mentioned checking the plus
& minus 15V supplies for the Servo Board when I told him the symptoms.
I had checked all of the Supplies earlier, (there are 13 DC supplies
in this machine), and when checked, it must have been on it's best
behavior.


Did you test them with a voltmeter or a scope?


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