getting started with 8i20
- clematites93
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01 Feb 2015 04:39 #55527
by clematites93
Replied by clematites93 on topic getting started with 8i20
Thank you for these new explanations, I am going to try what you propose.
If I understood well, I deduct that from it the anomalies observed in the oscilloscope (previous post) would result from a problem of alignment.
As English is not my _maternal language_, as you understood him, I prefer to ask for confirmation.
If I understood well, I deduct that from it the anomalies observed in the oscilloscope (previous post) would result from a problem of alignment.
As English is not my _maternal language_, as you understood him, I prefer to ask for confirmation.
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01 Feb 2015 05:19 #55530
by andypugh
I actually have no idea what your oscilloscope means, but that rather depends on what points you were scoping between.
Alignment is likely to explain non-smooth movement and especially different speeds in different directions for the same current and voltage.
Replied by andypugh on topic getting started with 8i20
If I understood well, I deduct that from it the anomalies observed in the oscilloscope (previous post) would result from a problem of alignment..
I actually have no idea what your oscilloscope means, but that rather depends on what points you were scoping between.
Alignment is likely to explain non-smooth movement and especially different speeds in different directions for the same current and voltage.
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02 Feb 2015 04:04 #55565
by clematites93
Replied by clematites93 on topic getting started with 8i20
Hello,
preliminary question, please. When I turn the shaft of my motor, without any electric connection of power, I feel 6 slightly _hard points_. Is it normal?
With a dc power supply (5 V), I find 3 clearly harder points (3 x 120 °). It seems to verify the conclusion of a previous manipulation which indicated that my motor has 6 poles.
Then, there is a net difference between the magnetic zero the closest to the stop point of the motor (from memory, approximately more 2000 counts).
Encoder 2500 x 4
Thank you for this very instructive manipulation.
Have to I envisage a mechanical realignment between the shaft of the motor and the shaft of the encoder, via the flexible coupling (_Allen screw_) or use the value of gap counts ?
preliminary question, please. When I turn the shaft of my motor, without any electric connection of power, I feel 6 slightly _hard points_. Is it normal?
With a dc power supply (5 V), I find 3 clearly harder points (3 x 120 °). It seems to verify the conclusion of a previous manipulation which indicated that my motor has 6 poles.
Then, there is a net difference between the magnetic zero the closest to the stop point of the motor (from memory, approximately more 2000 counts).
Encoder 2500 x 4
Thank you for this very instructive manipulation.
Have to I envisage a mechanical realignment between the shaft of the motor and the shaft of the encoder, via the flexible coupling (_Allen screw_) or use the value of gap counts ?
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02 Feb 2015 04:08 #55566
by andypugh
You can do it in software, the bldc component has a parameter specifically to correct for an offset between the encoder and the motor.
Replied by andypugh on topic getting started with 8i20
Have to I envisage a mechanical realignment between the shaft of the motor and the shaft of the encoder, via the flexible coupling (_Allen screw_) or use the value of gap counts ?
You can do it in software, the bldc component has a parameter specifically to correct for an offset between the encoder and the motor.
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03 Feb 2015 04:07 #55599
by clematites93
Replied by clematites93 on topic getting started with 8i20
Hello,
I did not very well understand the concerning explanation bldc. N.encoder-offset
The offset, in encoder counts, between the motor electrical zero and the encoder zero modulo the number of counts per electrical revolution.
If I bring in the value obtained on ( 2186) , the motor _is carried away_ with Axis about is the increment (0.1 or more)
I did not very well understand the concerning explanation bldc. N.encoder-offset
The offset, in encoder counts, between the motor electrical zero and the encoder zero modulo the number of counts per electrical revolution.
If I bring in the value obtained on ( 2186) , the motor _is carried away_ with Axis about is the increment (0.1 or more)
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03 Feb 2015 04:44 #55608
by andypugh
It doesn't matter _which_ motor pole you align the encoder with, basically.
Try -2186.
How many counts per rev is the encoder? You might need to try (total counts - 2186)
I have only once set up a motor to index, as an experiment, and that one was aligned already. You might have to experiment with numbers until something works.
Replied by andypugh on topic getting started with 8i20
Hello,
I did not very well understand the concerning explanation bldc. N.encoder-offset
The offset, in encoder counts, between the motor electrical zero and the encoder zero modulo the number of counts per electrical revolution.
It doesn't matter _which_ motor pole you align the encoder with, basically.
If I bring in the value obtained on ( 2186) , the motor _is carried away_ with Axis about is the increment (0.1 or more)
Try -2186.
How many counts per rev is the encoder? You might need to try (total counts - 2186)
I have only once set up a motor to index, as an experiment, and that one was aligned already. You might have to experiment with numbers until something works.
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03 Feb 2015 05:50 #55610
by clematites93
Replied by clematites93 on topic getting started with 8i20
My encoder (2500 x 4 ) rev per tour .
For both magnetic zeros the closest to the mechanical zero I obtain approximately (- 1733) for the one and approximately (+2186) for the other one.
I tried, quickly several values. It would seem that (+1000) would allow to have _ very boorishly_ the same speed in a direction and in the other one (in open loop).
With the _pid _ the motor speed is too slow so that we can detect something.
With Halscope, the supplied peaks --> pin hm2_7i43.0.8i20.0.2.current seem to have a less important amplitude (_without prejudice_).
If I seem to you to be on the right track, I shall refine the value.
For both magnetic zeros the closest to the mechanical zero I obtain approximately (- 1733) for the one and approximately (+2186) for the other one.
I tried, quickly several values. It would seem that (+1000) would allow to have _ very boorishly_ the same speed in a direction and in the other one (in open loop).
With the _pid _ the motor speed is too slow so that we can detect something.
With Halscope, the supplied peaks --> pin hm2_7i43.0.8i20.0.2.current seem to have a less important amplitude (_without prejudice_).
If I seem to you to be on the right track, I shall refine the value.
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03 Feb 2015 05:57 #55611
by clematites93
Replied by clematites93 on topic getting started with 8i20
I hope not to have made too many faults of translation 
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04 Feb 2015 04:45 #55655
by clematites93
Replied by clematites93 on topic getting started with 8i20
Hello,
Until I can make tries more elaborate tries, please, I would want to know if it is possible, in the future.... to replace the rotary encoder by a incremental linear scale associated with the movements of the table ((to compensate for the small errors of pitch of the ballscrew and not the very low supposed backlash).
What interests me most, it is to make tries.
Until I can make tries more elaborate tries, please, I would want to know if it is possible, in the future.... to replace the rotary encoder by a incremental linear scale associated with the movements of the table ((to compensate for the small errors of pitch of the ballscrew and not the very low supposed backlash).
What interests me most, it is to make tries.
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04 Feb 2015 05:05 #55656
by andypugh
No. You will always need something actually on the motor to commutate the motor. You can use linear scales for accurate position control, but you need the motor encoders _too_.
Replied by andypugh on topic getting started with 8i20
Hello,
Until I can make tries more elaborate tries, please, I would want to know if it is possible, in the future.... to replace the rotary encoder by a incremental linear scale associated with the movements of the table.
No. You will always need something actually on the motor to commutate the motor. You can use linear scales for accurate position control, but you need the motor encoders _too_.
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