Novel SCARA parallel robot with fully cylindrical workspace
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- Опубликовано: 6 май 2018
- This novel SCARA parallel robot has the combined advantages of serial SCARA robots with links of equal length and dual-arm SCARA robots. The new robot has all of its actuators on the base, and a fully cylindrical workspace with no voids in it. Finally, the robot has no so-called parallel singularities inside its workspace.
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The idea of the central linearly actuated push-bar to control the radial position seems ingenious!
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For the sake of here for brevity undisclosed reasons
I'm thinking about adding some compact 3DOF rotational wrist on the tip of a SCARA type robot
while keeping all the additionally needed motors in the base too.
Thus I turned to parallel SCARA designs to have two paths to distribute all the necessary mechanical through joint motion threading to,
thereby avoiding to have an excessively high stack of belts (or chains) on a single-arm-path.
The central push-bar adds a third path and helps further in "de-congestion" of the two arms.
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Keeping actuation for the z-axis in the base (in contrast to what is presented here) and
threading two actuations (rather than one as presented here) through each arm
already gives three rotational DOFs plus one gripper-DOF at the tip.
Nice.
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I guess if things don't become to fragile
one could even add a second or even third push-bar for yet more paths.
But these would sometimes poke out at the front too.
Interesting 🙂. Thanks for the video.
Very creative, thanks for sharing.
How does rotation at 0:08 work? - It's not shown in the see-trough part of the demo.
Also I see only three actuations: Two rotational and one linear motor, but
there are obviously four robotic DOFs: rotation, radius, height, endeffector-rotation
I miss one rotative motor rotating the stack of all the 5 center plates as a whole …
I don't understand how the upper motor moves the bottom gear. How is it connected to it?
Two passive arms seems just are mock arms. Otherwise it is standard RPP Cylindrical robot manipulator.
Aren't each of the joints a weak point? Why wouldn't you just use a single rail that pivots about the same point? The main problem I see for this SCARA is that it is more expensive than non Parallel SCARA machines in terms of material like motors and length of supports that I don't really see the point other than a high cost spectacle, sorry for the harsh criticism, it looks really cool, maybe a cost saving solution would be to make the machine to print all of its items sideways upon a wall or have a method of securing it to the ceiling like a hang printer, but at which point, why aren't you building a hang printer? It's tough, creativity should always be celebrated but never over indulged beyond reason.
Printer?
Perhaps it could be made into a laser engraver? Get rid of the z-axis rods on the end and channel a CO2 laser beam through the head. The advantage I would see with this set up for laser engraving is its speed. It also has more stability/ lower resonant frequency at the end effector compared to a similar non-parallel SCARA machine at roughly the same volume (or rather workspace used). These are just my thoughts.
@@jaredjones6570 I am rewatching this a couple years from now and I realize I was a bit overly harsh, this kinematic system does have its uses, I just cannot imagine them and that is a fault in myself.
In regards to speed, a delta or CoreXY system would be much faster because of the lower carriage mass with the Z-axis moved to the edges rather than the center. The biggest competition with this machine is probably a delta design which equally loses resolution with size, uses a very similar amount of space but is much much faster.
In regards to reliability, a cartesian is relatively fool proof and popularly used in laser cutters/engravers.
And either a high resolution LCD/projector or gyroscope mounted laser would offer the most precision (I am thinking DLP or SLA 3D printing) potentially best orientated over say a waffer with a cartesian system (this is a popular/somewhat recent method for building modern processors in desktop/laptop computers).
Versatility will be maintained by +4-axis CNC machines like CNC mills or robot arms. Hard to say how it compares with a single arm SCARA popular as pick and place machines in industrial areas. There are certain SCARA designs that centralize their Z-axis rather than keep it at the end of their effector that could be more stable but even these machines have tough competition from deltas.
It is still a super cool kinematic system. Mesmerizing to observe and that alone could make it a great machine for the right price.
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