Dynamic Blocks

[tylerXDY5A]

Hi All,
I hope someone here can help me with a problem that's been driving me up the wall.
I’m currently building a dynamic block for a 120-ton mobile crane. My goal is to have the radius control the boom’s movement through a stretch action combined with various constraints, which I’ve been able to set up successfully. However, I’m struggling to get the luffing cylinder to move appropriately in relation to the boom’s movements. I’ve seen setups where this is achieved using a rotation action based on the boom’s angle, but that approach doesn’t suit my needs, as I want the movement tied to the radius rather than the angle.

I’ve experimented with polar stretch actions and linking parameters through the Parameters Manager, but I haven’t been able to get the results I’m looking for. Additionally, constraints such as Aligned and Angular Constraints are applied, but the luffing cylinder still doesn’t behave as expected with the boom’s movement. If anyone has experience combining stretch actions and constraints in dynamic blocks or knows a solution, I’d really appreciate the help!

Thank you in advance.

[Libbya]

Post the block.

[tylerXDY5A]

Okay will now

[j.palmeL29YX]

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@tylerXDY5A wrote:

If anyone has experience combining stretch actions and constraints in dynamic blocks ...

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My experience: Do never mix Dynamic Parameters/Actions with Parametric Constraints. Such blocks will fail in most cases. 

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@tylerXDY5A wrote:

 I want the movement tied to the radius  

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Which radius? I don't see any radius in your model. 

If you mean the length of the cylinder, see the attached suggestion. (choose an appropriate Cylinder_Length in the range between 8400 to 6000).

Otherwise please clarify what you want. 

[tylerXDY5A]

Hi Jurgen,

Thank you for your help, the movement of the cylinder is what I am looking for however, I would like it to work in relation to the booms horizontal movement (radius) in my original example. Is there a way to link the Cyl_length with the original movements of the lines coming from the booms tip to the centre of slew. the main aim so to be able to type in the distance from the centre of slew to the lifting point (radius) and have everything move as it would in the real world. 

I hope the attached snip helps it make a little more sense.

[tylerXDY5A]

Hi All,

I’ve made some progress on this block but have encountered further issues, particularly with how the carrier is now rotating. I was hoping to get your opinion on whether it’s a good idea to continue building the block in this way. Even if I manage to keep the carrier in place, I’ll still need to ensure that every boom length functions properly with the hook, fly, and other components. My primary goal is to create a model that is simple enough for anyone to use and understand based on the radius.

Please see the attached for my current progress and let me know your thoughts!

[j.palmeL29YX · Accepted solution]

My next attempt attached. 

[j.palmeL29YX]

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@tylerXDY5A wrote:

Please see the attached for my current progress and let me know your thoughts!

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Your block in "AutoCAD_Example - TH.dwg" can not work as long as you have added both Dimensional Parameters Cly_Distance and Crane_Radius. If you want the user may be able to change both independently you must allow to the telescope beam to extend. 
To do this, you first must explode the "12.5m boom length" block, so the 7 subblocks reside in the top level of your main block.
Now add the needed constraints for automatically adjustment o the beam length. Of course before that you have to decide in which manner the telecope shall work. There are several possibilities - two of them are demonstrated in the attached simplified example. 

Good luck 

[tylerXDY5A]

Hey Jurgen,

Thank you again for your help—I’m very conscious of not taking up too much of your time, and I greatly appreciate the solutions you’ve already provided.

I’m taking a different approach than your example because cranes can reach the same radius with various boom lengths. Each length provides different lifting capacities and boom heights, which are critical when working in areas with limited space and access. I’m hoping to use a lookup table, combined with either a move or stretch parameter, to dynamically shift between the different Boom Lengths (individual blocks). Each block would then be controlled individually by the radius.

This presents its own set of challenges, especially in aligning the hook, auxiliary booms, flys, and other components with each boom configuration. My goal is to create a model that is straightforward for anyone to use and understand.

I haven't made much progress with so far. Any further thoughts or advice you have would be greatly appreciated. 

I will repost the block once some progress is made if possible. 

Thank you,

[j.palmeL29YX]

"cranes can reach the same radius with various boom lengths"

Attached a next example - you can fix the radius and see what happens if you change the Cylinder length and you can fix the cylinder length and see what happens if you chance the radius. You can play with these both parameters and explore how the crane works. 

"I’m hoping to use a lookup table, ..." 

Be aware, that constraint parameters can not used in lookup tables. If you urgently need (or want to use) Lookup's you must avoid the using of constraints in your block. (FYI: Block action tables can use constraint parameters). 

"... set of challenges, especially in aligning the hook, auxiliary booms, flys, and other components "

If you need more help, let us know. Until now I have no clue about your intentions. 

"not taking up too much of your time"

 Don't worry about wasting my time. For me are such challenges welcome brain jogging. 😉

[j.palmeL29YX]

An off topic note: 

While editing the file, I had to struggle with some drawing inaccuracies. As example the hatches in the beams is a complete mess. (The attached image shows which hatch is placed on which layer). If I were you, I'd clean up this mess first... 😉 

[tylerXDY5A]

The problem for is trying to create the relationship between these two parameters. The Crane itself has 14 different boom lengths from 12.5m to 68m. I now see the problem that arises from trying to work with actions and constraints as it obviously throws the whole thing out when interchanging between. 

If there was a way to add in the ratio between the radius, cylinder and boom length. I think this would be possible but obviously AutoCAD is quite limited in the type of formulas you can have. 

I've added the over sections for your understanding.

[tylerXDY5A]

I'm not going to lie my attention to detail with my hatching has never been great haha. However, in my defence the block from the manufacture was extremely broken and all over the place. Besides redrawing the whole thing again, I worked with what I had to get the colours and look I was after.  

[j.palmeL29YX]

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@tylerXDY5A wrote:

... create the relationship between these two parameters.   [>>which two parameters?<<]

... a way to add in the ratio between the radius, cylinder and boom length.   [>>three variables<<]

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???

Some questions for my understanding: 

1.: The block needs 14 different boom length's (which you have shown above).  These 14 different lengths, are they fix and do not need to be dynamically changeable (as I demonstrated in the video above erroneously)? Is that right?

2.: If so, am I right in next assuming that certain ranges of the radius are each assigned to a certain boom length? (e.g. the user chooses a radius 2500...3500 what activates automatically the boom length 16500, radius 3500...4500 activates the boom length 20500, radius 4500...5000 activates the boom 24500 and so on)? Or do I completely misunderstand your intention? 

I have not yet a solution. First I need to understand the intended functionality.

[tylerXDY5A]

1. It would be preferable to change between boom lengths as required. However, this is where I encounter challenges, as I don't fully understand the intricacies of AutoCAD and whether the program allows adjustments between constraints, actions, and formulas—or how these interact within its framework.

2. Each boom length has a range and capacity, typically influenced by the boom's angle. For example:

• A boom length of 12.5m provides the crane with its greatest capacity at its smallest radius but loses significant capacity as the radius increases, reaching a maximum of 10m.

• Conversely, longer boom lengths allow for greater reach and capacity, depending on the extension ratio of each section—such as 0% (1), 50% (2), 96% (3), or 100% (4) extension.
  These can also vary between lengths, yielding different results (though this variation is less relevant for the block).

This highlights the critical importance of boom length selection, factoring in crane capacity, height, deflection, and other variables

I have attached a few pages of a load chart for you to have a look at.  

[j.palmeL29YX]

Sorry for my ignorance, but I still do not understand how you want the block should work.
Which input information shall be given (are expected) from the user? I think only the choose of any radius is not enough. Perhaps also a load, I don't know?

And after complete the input information, what shall happen?
Can you describe in a mathematical form, as example
IF <any condition(s)> THEN <what happens> ?

I can imagine,
- "conditions" may be a radius, and/or a load, and/or the cylinder length(?) or any others.
- "what happens" may be how far the individual boom segments are extended, and/or the boom length **) and/or the cylinder length or what?

**) BTW: I don't right understand what are the different boom length. Does it mean the hook is placed on different boom segments, or does it describe a range of allowed length's values or ...?

Is it possible to explain that for a stupid layman. I'm afraid I have to give up because I don't even understand the intended design goal (and of course I'm still a long way from how to implement this in a block). 😞

[tylerXDY5A]

No need to be sorry at all.

I see now where my previous explanation may have caused confusion. I tried incorporating a formula to link the cylinder and the radius—an issue you resolved using constraints. My concern arises when the boom extends, as previously illustrated in BoA and BOB. The radius would adjust along with the boom's movement. However, I want these two aspects to remain independent. This means I should be able to select one of the preset boom lengths (as per the details I provided). Once a boom length is chosen, the radius would independently control the movement without affecting the boom length.

Example:
If I select a boom length of 68m at a radius of 28m, I should then be able to extend the radius to 40m while the boom length remains fixed at 68m. Then Change to another boom length of say 36.5m and go through the same process. Hopefully selecting freely through all options. 

To clarify further, the boom segments are pinned in place using a holding pin at specific percentages to create the predetermined boom lengths. These lengths are fixed by the manufacturer and represent the only distances at which the crane boom can operate.

Yes, this precisely describes the distances that the hydraulic extension of the segments creates, forming the total boom length.

[j.palmeL29YX]

Oh yeah, now I think I understand your intention. 

Attached my next attempt. Because I don't know the allowed min/max length of the cylinder perhaps some small adjustments of the allowed ranges for the radii will be necessary. 

HTH

And I repeat: I'd suggest to clean all your blocks. As said above you should simplify the hatches (some blocks include hundreds of separate hatches, other have overlapping hatches, some are on wrong layer  and so on).

And additional I'd suggest an "overkill" in all block definitions. In the image you can see, that even a simple boom includes a lot of problems which expect a repair. The other blocks are similar. This will cause performance problems. 

[j.palmeL29YX]

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@tylerXDY5A wrote: [via PM]

Could you please explain how you achieved these movements?

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The main principle of my suggestion is rather simple. In the Video below I'll try to demonstrate how it works:  

- The first line represents one of the booms which you have shown in the post #12. (For each of theese booms I created a separate block definition). The left endpoint and its length is fixed, so it only can rotate about the left endpoint.
- The next line stands for the radius. Its left end is placed (and fixed) in the rotation center, the length is driven by horizontal constraint parameter.
- The last step is a vertical constraint between the right end of the boom and the right end of the radius line. That means, the right end of the boom must always stay vertically above the right end of the radius line. This is geometrically only possible if the angle of the boom changes with the length of the radius.

This is done for each of the 13(?) different boom lengths and can be selected by diffenrent visibility states.

I hope that helps you to understand the "secrets" behind the suggestion.