Rigging my Hydrualic Excavator - Am I Doing it Right?

Here is a hydrualic excavator im working on that will be a game object eventually in Unity (far far far down the road)

http://www.blendertek.com/Blends/Tutorial%20Version%20Personal4_test.blend

The blueprints are packed in the .blend

Am I rigging the arm correctly by creating a seperate armature for every knuckle of the boom and then creating a child of constraint from each, the way I currently have it? this allows me to pose them all manually without any deformation but I dont know if there is any easier way to rig this that will make everything easier in the end.

I think I’ll be able to figure the pistons out with all the tutorials on youtube and Johnathans W’s 2.5 piston rigging tutorial from blendercookie, otherwise, any help, suggestions, video tutorials or such that will help me learn more about mechanical rigging ang to apply to my model in particular? Im doing youtube tutorials on this so I cant continue until I get this rigged ‘properly’.

Thank you very much.

The Blender Cookie tutorial should show you how to rig the whole arm with one armature and still get no deformation… use one armature, join the whole arm into one object, use select-linked (L key in edit mode) to asign each discrete piece a vertex group.

There are two ways to rig a hydraulic cylinder or chain of hydraulics, e.g. an excavator. You can use bones or empties and constraints/drivers. Actually there are three ways: Armatures, Empties and constraints/bones, or the wrong way! I too suggest you read the tut mentioned above, it can be improved upon once you get your head around it, particularly at the bucket end where he has used equal length pivots, most diggers have un-equal length to make the bucket tilt further for less cylinder movement, but that’s just me being picky.

Below a blender file with the two ways in simple form, including a typical two arm and further object setup using empties, etc. Just press PLAY to see it operate. For the armatures just rotate, scale or grab the “crank” bone in each armature. To operate the empties version, just disable the drivers on the empties first.

cylinder-problem-ver2.blend (802 KB)

You are on the right track but still have a way to go, keep up the good work. :evilgrin:

Herewith, an early stage picture of my digger - now complete:


BTW. You should NOT have separate armatures for each section - this will give you horrendous problems once you start to rotate and move the whole thing. Either use ONE armature or empties with drivers and constraints as my blend file.

Thanks guys, I downloaded Johnathon Williamsons how to rig an excavator arm and pistons tutorial and how to rig a piston tutorial but those are from 2.5 even though everything still applies. Is using empty groups still the best option? I realized seperate armatures for the boom is the wrong approach. I was thinking there was only the ‘deform mesh from armature’ option, I’m extremely new to blender and rigging specifically. I’ve also never used drivers and barley know what they even are let alone work, and I’ve never rigged something with empties. Any great tutorials on that which stand out from the 100’s on youtube? Again I’ll take any information, text, video, .blends anything. I love to learn new concepts and techniques.
Here is where my armature is at right now:

Here is the .blend from the end of the video: [http://www.blendertek.com/Tutorials/Blender/ModelRigExcavator/part 2_armature.blend](http://www.blendertek.com/Tutorials/Blender/ModelRigExcavator/part 2_armature.blend)

Does everything looks on track so that when I assign my rams to the vert groups and the knuckles to the vert groups it will work properly? I Know the dual rams for the first knuckle works fine, but the ram that pushes the second knuckle up and the ram on the second knuckle that pulls the third knuckle im not sure if I have the controller in the right spots. Any info on my .blend (or the tutorial) is correct or changes need to be made, since this is for my personal use in a game and for a youtube tutorial. (I’m not completely sure on the bucket yet, will have to experiment)

Thanks.

Mechanical models are often, nearly always, best rigged by parenting the mesh to the armature “With Empty Groups” and then assigning the required vertices to the required bones in Edit Mode after you have built the mesh. If you have two cylinders, make one and rig it to the armature then simply go into Edit Mode and duplicate it in side it’s own object. The second cylinder will then copy exactly the motion of the first without you having to rig it. You only need one set of bones or empties to drive two cylinders doing the same job. I don’t know of any tutorials on the subject of rigging with empties and drivers, I do not particularly like youtube tuts - many are pretty amateurish, probably explaining why they aren’t published on a recognised Blender training site, I use www.cgcookie.com tuts or build myself a SIMPLE example to understand the principle. Feel free to pull apart the blend file I left you in a previous post. Use the Graph Editor to see the F-curve or Driver details. Finally, you could also read the manual pages on the subjects you are trying to learn, you can read at your own pace rather than watch a video at it’s pace. Keep up the good work, Clock.

PS. If you don’t mind me saying - you are trying to run before you can walk with this project. try something simpler first, with just say one crudely modelled moving jib operated by one cylinder, so you understand the principles first. Then gradually make it more complex and more realistic.

Got it figured out thanks guys. Way easier than I thought.

As the tutorials well-show, mechanics are often best constructed in exactly the opposite way from how they actually behave in real-life. For example, while a real-life piston of course drives the real-life movement of whatever it may be connected to, the best way to animate it is to key the movement of the thing that is being driven. Then, use constraints to cause the piston-assembly and so-on to follow it. Empties are used to identify the points-of-connection, and “move-to,” “track-to,” and “point-to” constraints cause the resulting motions to be correct.

(By the way, your model looks like “a jet-engine powered mechanical toy,” which I think would be great fun, if that’s what you’re going for …)

the bcookie way is the only way that i know of. so many ways to do it but they all have draw backs and do not work quite right. Thats my vote

Not exactly… they are supposed to be two V16 diesels with generators and hydraulic pumps. The model was based loosely on an O & K RH400. At the stage when I took the snapshot, I had not even started to get the materials correct or the mud splattered over it! But now you mention it - maybe I’ll put a couple of Rolls-Royce Trent engines in there and polish the bodywork teehee.

On a serious note - I have found it far better to reverse engineer the model, i.e. move the business ends of the model as they should be moved and then let my rigging take care of the hydraulics. When I was taught to drive a real digger, the old guy told me to watch the bucket only and threatened to smack my head if he caught me looking at the levers or any other part of the digger! One sore head later I could dig…