ARMBot 2.0 – Grade 10
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This year me and my project partner Reilley Pfrimmer have decided to convert our arm from LEGO to 3D printed and metal fabricated parts, and with any good idea you need a model!
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UPDATE: 1
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Below is an 3D image of the CAD file for what the arm structure will be made of. This structure is what will be linked together to ultimately make the arm.
The red structure is what will make up the forearm and bicep, this will be powered primarily by gears. The orange structure is what will make up the shoulder, as you can see this one is slightly different than the red structure, this is because like the LEGO prototype from last year it will be powered by a linear actuator which requires an external point to create rotation.
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This here is the 3D model for the basic structure for the arm. This model isn’t functional as it would need brackets, gears, linear actuator and more, more on this later
As you can see the red and orange parts from above they make up the main structure for the arm the shoulder, forearm, and wrist, they are all connected together by axels on the joints these will be made of 8mm diameter steel round stock.
The blue part is the baseplate it has a bunch of teeth surrounding it, this is because it will be spun by two smaller gears creating rotation and allowing the arm to be able to reach places in three dimensions instead of just two, this is quite the upgrade from last year and will make this arm much more capable.
The pink part is the part that will hold the whole arm to the block of wood and still allowing it to rotate on the final printed model this part will be buried within the wood so it most likely wont be seen.
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This above is the model for the linear actuator, it goes between the rotating base and the third axel of the shoulder piece and will act as the deltoid muscle on a human arm.
The main turquoise piece is the main structure it is what is keeping the actuator rod straight.
The detached turquoise piece is there to hold the purple axels straight and to provide stability when they are in use.
The tube like turquoise piece in the rear is there to attach the whole structure to the rest of the arm.
The main blue gear in the middle is the work horse of the operation it is what acts upon the red actuator rod and make it move in or out.
The red toothed piece in the middle of it all is the actuator rod this is the part that connects to the third axel on shoulder of the arm when powered by the main gear it will cause the shoulder piece to rotate.
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Here above is what the arm looks like when the linear actuator is installed and retracted with the shoulder upright 90°
This works when the linear actuator extends it acts upon the external axel on the shoulder causing the main rotation point axel to rotate clockwise, (when the linear actuator is on the right side when viewing).
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UPDATE:2
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Below is the new and improved base plate comprised of an updated actuator attachment point, smooth surfaces and more!
Something that may be quite apparently different from the previous model is the smooth and less jagged surface including what was before sharp edges are now smooth fillets, not only does this make the model look quite a bit nicer it also serves a legitimate purpose and that is to more evenly distribute stresses along corners which are normally hot spots for breakage.
Another change is the two protruding mounts these were in the old model but now they have been modified and cleaned up.
I have also strengthened previously fairly thin and weak areas like the two large arm mounts that are used to hold the entire arm up these previously were too thin for my liking.
On the left is the main base plate this is what everyone will see and be the one with the most purpose, in the model on the right you can see a piece on the bottom of the main base plate and this as i have explained in the previous update is to allow the main base plate to rotate while being on the piece of wood that will be put underneath.
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This here is the model of the entire ArmBot (minus the actuator and electronics).
The main difference between this model and the previous model is that this model was made in fusion 360 where as the previous model was made in TinkerCAD.
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UPDATE:3
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Here is the fully remade linear actuator.
If you are curious you can go through the models annotations to get a visual with a short description.
but its roughly the same just made with a more sturdy and more reliable design in mind.
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below is the new assembled model for the arm.
Annotations included for any curious Georges
This is the arm model with the new linear actuator model integrated just like it would be in real life.
None of the fundamentals of the arm have changed but there have been spacers added between the parts to ensure they stay the desired distance relative to each other.
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UPDATE:4
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Here is the final working model for the linear actuator
This is the final version for the linear actuator with the addition of a bracket to hold the stepper motor in place.
This final model of the linear actuator has been proven to work which will be shown later below
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This is the updated ARMBot model
In this model there have been several new things the obvious one being the updated linear actuator but the other major update is the addition of two servo motors in the furthest section this brings along a bracket that will help keep it in place.
As you may see there are two servos but only one bracket this is because the second servo is a kind of precautionary addition this is for if one servo alone isn’t enough torque so the addition of another would be necessary.
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Here is a video of the linear actuator on the arm actually working! (Ignore the background talking)
As you can see above we have successes with the arm moving as intended with no apparent issues apart from maybe cracking the bracket but I cant say for sure.
In the video you can clearly see that we are using a large Lab-Volt power bank this is because the current draw from the stepper and future servos will be too much for 9v batteries to handle, the power bank is outputting roughly 6V(max for stepper) and >5A (that’s the max of our ammeter).
Midway through the video you can see that I am controlling the arm using a serial monitor, this is just temporary and the final arm will be controlled by a software developed by Reilley for more accurate movements and the ability to do specified tasks.
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UPDATE:5 (Milestone)
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The arm has officially been dubbed “ARMBot” the capitals are important to the significance of the name.
Above is the current “digital” model of the ARMBot, at this is pretty much the end of the project, with the year coming to a close both myself and Reilley have decided to go our own separate ways next year me personally will be working on two projects, one: an induction furnace and two: a gear display for Mr. Csuka. Reilley on the other hand is still deciding on what he wants to do next year but he has already stated that this project was not something that would be worth continuing. Don’t get me wrong this project was amazing and although it didn’t fully work in the end it was not at all a failure, the point was to learn and boy oh boy did we ever, we learned soo much from this project
In the end it was not fully functional, but! it was amazing and checked all the learning boxes.
