Bones 2
At this time we are ready to add the remaining bones and start filling out the sub-groups with shapes. The bones can be placed in any initial starting position, so to keep it simple, we will put all of the bones in a line going in the X direction. The next two bones will be standard length of one and the last bone will be scaled to approximately 1/3. The position of the bones prior to being moved to sub-groups are
XYZ (4.5, 1.75, 6.0), XYZ (4.75, 1.75, 7.0) and XYZ (4.5, 1.75, 7.75)
Not working with angles will make adding shapes much easier. Note that after becoming sub-groups the X and Y positions are 0.0 and only the Z component changes. When using the Pro version, CTL-Click on each group to select all of the groups, and click on the Plug-Ins tool and select "Create Unique Names". Now the hierarchy looks like the one here.
Now create 4 "motor" cylinders scaled to XYZ (.25, .50, .25). Rotate each 90 degrees on the X axis and position. Locate the cylinders at the base of each bone, just as a motor would be placed on a robotic arm. To see where the cylinders were located prior to being moved into their sub-groups, download and look at Joints_08_15_2012_pm3.3DC (404 kB) . Click on each group and click the properties tab to see the placement. I would suggest making screen copies of each to use in your own layout. The cylinders are now ready to be moved into their subgroups Group3, Group4, Group5, and Group6, as shown on the right.
By adding a pair of yellow rectangles between each pair of cylinders, we arrive at the scene Joints_08_15_2012_pm4.3DC (460 kB) as shown below. Again, each pair of rectangles were created and positioned prior to being moved into the appropriate sub-groups. When the three pairs of rectangles were in place, a simple red cylinder was added to Group6, along with a pair of paddles. This is the end-effector for doing work with this robotic arm.
In order to make the arm more realistic, we can add more detailed motors to each motor cylinder. That we will do later.
Now we will animate this arm by setting a "rest position" and rotating the groups to the desired positions for each point on the timeline. Warning, if you don't give enough time for the groups to reach the position, things go downhill fast. Also note that the Pro version of 3DCrafter has it's own build\t in rendering tool. Without this tool we would be limited to screen captures to record animations. Unfortunately screen captures are not the best quality for real time animations, but sometimes they will suffice.
With bones in place we can easily move the joints to new positions by clicking on any element in a group and using the rotation bars at the lower right hand side of the animation, or more precisely by using the group properties. It will be a good idea to record the starting position so that the arm can be returned to that position at the end. This will make the loop video run much smoother. If you are using the free edition and screen capturing the animation with something like CamStudio, you will need to click on each bone and click hide to keep the bone from being visible in the animation. The Pro version has a rendering camera that automatically takes care of the rendering internally.
The higher quality Windows Media Video of this anaglyph animation can be downloaded from joints_08_16_2012_am1.wmv (1,5 MB) .
The completed 3DCrafter file can be downloaded from Joints_08_16_2012_am1.3DC (456 kB) .
With about 30 minutes work, you can add small motors and change the Group5 to a single arm. This can be downloaded at Joints_08_16_2012_pm1.3DC (524 kB) . Additional detail, along with lights and shadows, will make the model more photo-realistic.