C_R

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6 years, 137 days

MaplePrimes Activity


These are replies submitted by C_R

 I thought I could do the labeling myself, which turned out to be more difficult than expected.

@OD 

Print layout mode was introduced in Maple 2022.

@Christian Wolinski 
Works excellent.

Thank you!

I have seen (and reported to Maple Support) a similar reduction in font size with Maple 2022.
I have attributed this to the 4k Monitors I am using. (This is an unconfirmed assumption.)

What type of Monitor do you use? Can you try other displays?

Do you see the reduction in fond size also in the newly introduced print layout mode?

@Joe Riel 

That works for GetMultibody()

FYI: Get Parameters also does not list "a"

A:-GetParameters()

for

Thank you for the workaround.

@Carl Love 

This is much clearer now. Maples initially known functions are actually procedures. I had overlooked that.

Thank you very much for this detailed explanation!!!

@Carl Love 

A lot to digest for a "yellow belt". Can you give me hint what  ''arctan''(algebraic) does?

Why the double right single quotes?

Works well.

Thank you!!!

@acer 

Always valid would be great, but I don't think that is possible. For now, I'd be happy with something I can check before I use it further.

Yes, this question is related to my earlier question. The difference is that this time I decided to use a step-by-step approach instead of solving sets of equations (as you showed with the "explicit" option, which I couldn't get to work this time). 

For some reason the solution switches between arctan and -arctan output after changes and/or re-execution of the document. That’s how I deal with it at the moment…

I could have asked for a solution that converts an arctan expression with a quotient as an argument. But I have the feeling that solve has more valuable information.

@one man 

For completeness, if someone wants to follow up on our discussion:
If I replace the central link with a telescope I get this compression.

 

Running your program I get (in Maple 2022):

Error, (in Plot:-AnalyzeData:-StandardizeData) points cannot be converted to floating-point values

 

 

@one man 

Your set of parameters only works in MapleSim if I add a prismatic joint to the link in the middle (i.e. allowing compression and extension of L5). The observable compression is (encircled in red) is substantial.

The solution that works in MapleSim with links of equal length does not accept the slightest deviation from 2/sqrt(3). The error message "DSN/RunSimulation: internal error: unable to find matching" is the same that I get with your parameter set. It indicates that a consistent set of equations for the numerical integration can't be established.

It is unsatisfactory that we cannot reach a better agreement. It seems that an expert in kinematics is needed to sort this out.

 

 

@one man 

If so, I don't get it to work. It only works in MapleSim if all links are of length 2/sqrt(3) at 2 units distance of the vertical shafts

A very nice and interesting case! This raises some questions:

In which sense do you consider the “transitions between points” not being continuous? The aminations look smooth.

I understand the deformation as an extension/compression of the link in the middle (yellow bar in https://www.youtube.com/watch?v=Ekqn4sP8JxY). If this is correct, how do you define and measure distortion?  

I have tried to replicate your animation in MapleSim. It partly works but jams after a few rotations. I think I have done something wrong with the geometry. How long are the links in your lower animation?

To your knowledge, has the forward kinematics of the vertical shaft on the right in your animation (angle of the blue shaft in the youtube clip above) been derived by someone?

In general, is the method you are applying capable of tracing one solution of inverse kinematics (here is an example that switches between two analytical solutions. https://www.mapleprimes.com/questions/219294-Issues-With-Angular-Displacement-In#answer286194)

the link does not open a document

@one man 

It’s about doing inverse kinematics without involving equations.

Acausal modeling allows to swap inputs and outputs of a (computer) model. On the contrary, in a conventional block diagram of a system (and corresponding computer tools) the flow of information always goes from input to output. Strictly speaking acausal models do not have input and output. A model can be simulated in forward and backward direction (https://www.youtube.com/watch?v=YZWhMQ-0cEE&t=19s @ 17 min explains why and how). Exploiting this for inverse kinematics is new and not obvious (i.e. inventive).

I took the term "Inverse Model" from https://www.youtube.com/watch?v=X0OZ9EM6dns (@ ~7min). I have not found anything better or more appropriate yet.

Inverse models are useful for studies in an early conceptual design phase. Deriving equations is the next step.  Can the method for deriving equations to which you refer be used for parallel kinematics (e.g. a stuart platform in the video above)?

Thank you for pointing out the method of dimensional reduction. I was not aware of it.

Could you provide an example how Maple prints in your setting and what you want to achieve?

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