rotary-Z axis: i need to understand the variable resolution handling September 10, 2015 11:54AM |
Registered: 9 years ago Posts: 1,035 |
Re: rotary-Z axis: i need to understand the variable resolution handling September 10, 2015 11:50PM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 05:03AM |
Registered: 9 years ago Posts: 1,035 |
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The big issue with most high-ratio extension mechanisms like scissor lifts [...] is that there's a non-linear relationship between actuator motion and stage motion. So you need to get the kinematics into firmware, and resolution isn't constant. So some cleverness is required...
Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 05:45AM |
Registered: 8 years ago Posts: 17 |
Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 07:02AM |
Registered: 9 years ago Posts: 1,035 |
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penndu
the lowest resolution you have is A*R, with A in radian (formally R*cos(A)), if A is the angle for one motor micostep.
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penndu
In the software, you define your Z value, then you transform your Z value in theta value : if Z=0 is the lowest, then you have theta=acos(1-Z/R)
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penndu
then you transform your theta (who is in radian) in microstep : nb microstep=theta*A
Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 07:20AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 08:10AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 09:01AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 09:42AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 09:55AM |
Registered: 9 years ago Posts: 1,035 |
cause it's confusing me. As far as I knowQuote
theta1=acos(1-Z1/R)
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angle=arcsin(opposing leg/hypotenuse)
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number of microsteps=theta*A
Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 10:08AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 10:25AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 10:32AM |
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realthor
Isn't theta=arcsin(Z/R) the right way and #microsteps=Theta/A ?
Regards.
Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 11:14AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 04:02PM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 11, 2015 04:15PM |
Registered: 9 years ago Posts: 1,035 |
Quote
penndu
1) theta1=acos(1-Z1/R)
theta2=acos(1-Z2/R)
2) delta_theta=(theta2 - theta1) you get nnn.mm microsteps
3) you round the number of microsteps at the nearest integer value
4) you move this value
5) you memorise the value of the difference between microstep_rounded and microstep
when computing the next move, you add a step
2.5) microstep = microstep + memorised _difference_of_prior_step
Re: rotary-Z axis: i need to understand the variable resolution handling September 12, 2015 05:03AM |
Registered: 8 years ago Posts: 17 |
you must modify the code for the calculate_SCARA_forward_Transform function and for the calculate_delta function who is just after in the marlin-main.cppQuote
realthor
Ok, you say that this logic is already implemented for Deltas or would I have to write the code for a rotary-Z? If yes, maybe I can get any hints on where to modify and what? I didn't touch so far any code in Marlin.
Re: rotary-Z axis: i need to understand the variable resolution handling September 12, 2015 12:07PM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 26, 2015 04:52PM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 26, 2015 07:31PM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 27, 2015 04:54AM |
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Re: rotary-Z axis: i need to understand the variable resolution handling September 27, 2015 11:37AM |
Registered: 11 years ago Posts: 177 |