Protoype Heavy Duty Robotic Arm Mk.1

Description

This is the prototype of a robotic arm I have been designing. And it is my entry for the Hackaday contest for the "Wheels, wings, and walkers" round. IIt is remarkably strong, and the fingers are able to grip, and pick up an 8.4 pound weight. (a gallon jug of water). It is also incredibly sturdy while remaining lightweight!

My goal was to create the strongest 3d printable humanoid robotic arm on the market, while remaining low budget, I was determined to create a modular, easy to repair design. Perfect for use in education or as part of a completed robot (Artistic interpretation of what the robot is going to look like is up in the gallery! Art by yours truly)

The design uses 7 servos, one for each finger, plus one extra for the thumb, as it can do both a "thumbs up" and grasping position. And two in the wrist, which was a last minute addition, so it could rotate while holding heavier objects,

Details

Hello all! My name is Gray and I am an artist and inventor in Los Angeles. Here is my new robotic arm design. It is remarkably strong, durable, and coordinated. And it can be completed for under $200 depending on what computer electronics you use to control it. It will eventually be part of a complete robot. Which I have already started designing, along with mk. 2 of this project. This project was inspired by my grandfather, who was an engineer for NASA and helped with projects as revolutionary as the moon rover. He also designed the flight simulator that the Apollo astronauts used to learn how to fly the lunar module. Every time he would visit me in my youth, he would bring along a robotics project to build with me, And I continue that tradition to this day,

One of the challenges I've had as a robotics enthusiast, is that while many of the open source designs out there are awesome, a lot of them are sometimes very difficult to assemble, have a high failure rate, and are then very difficult to repair. Many of them seem rather fragile, and wouldn't hold up in long term use, such as service robots or prosthetic devices, so while being low in cost to create, they may have a high long-term cost due to repairs and re-printing parts.. My goal with this project is to create a humanoid robot arm that fixes all of these problems, is easy to put together, and can lift a large payload, and ideally, I would like it to be the strongest open source 3d printed robot arm on the market.

This design is totally modular, meaning it can come apart and be put back together with ease, for easy repair and adjustments (anyone who has ever built a robot, knows how essential this is!). Each actuator is driven by a worm gear design on two bolts as a guidance rail system. For mk 2, I plan on making this design a bit more "elegant" but for now, it gets the job done, and well!

I think robotics are very important for the future of humanity, I plan on developing a smaller, more compact version of this arm as a prosthetic, as well as making it a part of an entire robot, which will have a whole assortment of functions for human interaction and assistance. I think the future of robotics will play a huge role in how we move humanity forward and change the way we look at the workplace. This robotic arm is designed to be easy to repair, easily to assemble, while remaining reliable and sturdy. It would also be perfect as an educational kit, which I may offer as a kit or download in the future when my design is perfected.

This is actually a re-design of my first prototype, which unfortunately broke during testing (see build logs 1 and 2), due to faulty 3d printer filament. But like any maker, rather than getting discouraged I saw it as a chance to improve my design! So we'll call this one the "mk 1.5"

Upgrades

New, notable upgrades-

- 4 more reliable, stronger fingers with flexible rubber joints, as opposed to 5 weaker fingers with rigid plastic joints

-Stronger, reinforced wrist gear, with dual servos. I found the old single servo

design, could rotate the hand with no problem, but struggled when the

hand was actually holding something with any weight, so I changed that!

Will probably come up with something more "elegant" for mk 2, but this

does the job!

-New actuator gear mechanism, allowing the fingers

to hold more weight without failing or damaging the servos, my goal is

to great the strongest, low cost 3D printable robot arm on the market,

while using only consumer-available parts. -folding, modular design for easy maintenance/part replacement.

-smaller, more compact design and reinforced with long steel bolts. This thing

is incredibly sturdy! While still remaining relatively lightweight.

Currently, it has successfully been controlled with both Arduino and EZ-Robot's software, and I am working on new ways of controlling it for different purposes.

Components

7 × hobby servo MG996r
1 × ABS filament Hatchbox 1.75 ABS
20 × Various bolts
1 × Flexible Filament
1 × High guage fishing line

View all 7 components

Project Logs

Collapse logs

Build Log 4: And we're up and running!
Gray Eldritch • 07/20/2017 at 06:32 • 0 comments

Finally got this arm up and running, and it works like a charm! It can be easily driven using arduino, and is currently hooked up to an EZb4 I borrowed from another project, to test some ideas for my entire robot. The modular design is great! Each actuator fits together to form the forearm assembly, and can be opened one at a time like a hinge for quick maintenance or cable tension adjustments, and all the cables run out the back. The whole thing is made to be sturdy, and is quite re-enforced! But it still remains fairly lightweight, and easy to manage.

The hand is incredibly strong for a 3d printed device, the heaviest weight I have lifted with it is a gallon water jug, which weighs approximately 8.4 lbs, but the fingers were easily able to support the weight. Although they did flex slightly due to the flexible joints, I may try to find a way around this in mk 2, but overall I am satisfied!
Build Log 3: Upgraded Fingers and Rotation Wrist.
Gray Eldritch • 07/20/2017 at 06:20 • 0 comments

After last week's filament disaster, I wound up using the same hand design from MK. 1, none of the faulty plastic was used for that part, and I was overall pretty happy with it! Especially the articulating thumb. The one problem I was having however, was the fingers would jam from time to time, being made of rigid plastic. So I fixed that by replacing the five plastic fingers, with 4 flexible-jointed fingers. This is also part of how I plan to make this design modular, more on that to follow. But all four fingers are easily, individually removable and replaceable. I had some leftover flexible filament lying around from a sample I was given at CES this year, so I managed to get my FLSUN delta printer to print out just enough joints to make the new hand. Flexible filaments are such a pain in some of the cheaper printers!

The dark blue material is printed in Algix filament. I love this material! It's make of algae and is non-toxic, and they have some awesome colors. Unfortunately, I'm working on an artist and college student budget, so I can only get it for special projects like this one. It is a bit coarser than some other filaments, this caused some problems when fitting the rubber joints, when they slid right into and ABS finger, But after a little tinkering, I managed to get them all to fit.

The rotation wrist has been upgraded with a second slave servo, I found just one had enough power to move the hand, but really struggled when the hand was holding something. I plan to eventually make a more elegant solution to this, but for now, this does the job very well! The central gear also has a steel bolt running through the wrist, into the hand. Eliminating the previous arm's biggest weak point and making it remarkably stable for a 3d printed part!
Build Log 2: MK 2 Servo Actuators
Gray Eldritch • 07/20/2017 at 05:28 • 0 comments

Just here with a quick update on my modular robotic arm! This is my new servo actuator design, like many other robotic arms, I will be using high-tension string as tendons, and an actuator to push/pull them. But with the new, flexible hand design, only one direction of force is needed to open and close the hand. The hand closes when the actuator pulls on the tendon, and opens on its own upon release of the actuator, due to the elasticity of the flexible joints. Uses low cost MG996r servos, and has about a 4:1 reduction. What I like about this design, is when stopped in a position, it locks in place. Meaning it can carry a lot more payload without putting much strain on the servo motor!
Build log 1: Minor setbacks and a forearm redesign - MK 1.5
Gray Eldritch • 07/20/2017 at 05:22 • 1 comment

So... After I thought I had a working design, I wound up having some problems with a spool of ABS I bought, within a few days of printing it started to crack and peel and become brittle (see photo), and even after trying to fix it with acetone, I decided I should count my losses and start from scratch on the forearm. Never seen that happen before! But like any maker I saw it as an opportunity to improve my design even further, rather than be discouraged! I'm calling this one the "Mark 1.5" because I re-used a lot of parts from the original, just in a different configuration!
MK 1 (before the plastic broke down):

MK 1.5 upgrades:
- 4 more reliable, stronger fingers with flexible rubber joints, as opposed to 5 weaker fingers with rigid plastic joints

-Stronger, reinforced wrist gear.

-New actuator gear mechanism, allowing the fingers to hold more weight without failing or damaging the servos, my goal is to great the strongest, low cost 3D printable robot arm on the market, while using only consumer-available parts, as well as having a modular design. After this proof of concept, I hope to develop a new "Mk 2" version where all the motors are housed within the hand, so it can also be adapted to prosthetic use.

-Folding, modular design for easy maintenance/part replacement.

- smaller, more compact design and reinforced with steel rods. Sturdy and reinforced, while still remaining relatively lightweight.
That's all for now!