How Home Made Robot Arms Used To Be Made

With laser cutters and 3D printers in our arsenal as well as the global toy shop of mass-produced parts and single-board computers, building a robotic project has almost never been easier. In times past though, there was more of a challenge, with a computer likely meaning a chunky desktop model and there being no plethora of motors at low prices, a robot arm required more ingenuity. [Marius Taciuc] shares with us an arm he built from the most minimal of parts back in 2003, and it’s a beautiful exercise in creative reuse.

The arm itself uses metal and FR4 for its structure, and borrows extensively from cassette tape mechanisms for motors and gears. The stronger motor for the forearm is a geared unit from a heating system, and to control all this, a relay board is hooked up to a computer’s parallel port. This last assembly is particularly ingenious, having no optocouplers handy he made his own by coupling LEDs to metal can transistors with their lids removed.

The arm was entered in a competition, and he relates a tale with which we’ll all be familiar — at the critical moment, it didn’t work. Fortunately a last-minute accidental covering of the board with a floppy disk solved the problem, as it turned out that enough light was leaking into those home-made optocouplers to trigger them. The prize was won not just on the strength of the arm, but on his explanation of the lessons learned along the way.

The once-ubiquitous parallel port is now absent from most computers, but there’s still plenty of scope for experimentation if you have one.

3-DOF Robot Arm Wrist Without The Motor Weight

A major challenge of robotic arms is the weight of the actuators, especially closer to the end of the arm. The long lever arm means more torque is required from the other actuators, and everything flexes a bit more. To get around this, [RoTechnic] moved the wrist stepper motors off the arms entirely.

He built a push-pull mechanism that uses braided fishing line to transfer motion to the robot arm’s wrist using Bowden tubes. The motors are mounted on the arm’s base, with a drum and two lengths of fishing line on the shafts. The lines pass through an adjustable tensioner before entering the Bowden tubes. This drum mechanism is also present on each of the three rotating axes of the wrist.

[RoTechnic] used an Arduino-powered RAMPS board as a controller, which is programmed to accept over the serial interface. He created a simple GUI and scripting interface in Jupyter Labs to generate and send command, which seems like an excellent solution for testing.

We can see this mechanism being a useful for a variety of motion applications, and definitely something to add to the idea toolbox. It is somewhat similar to some other cable-operated joints we’ve seen in humanoid robots and other 3D printed arms.

Continue reading “3-DOF Robot Arm Wrist Without The Motor Weight”

close-up image of a philodendron houseplant with electrodes attached, connected to a robot arm holding a machete

(Mostly) Harmless Houseplant Wields Machete

In a straight fight between a houseplant and a human, you might expect the plant to be at a significant disadvantage. So [David Bowen] has decided to even the odds a little by arming this philodendron with a robot arm and a machete.

The build is a little short on details but, from the video, it appears that adhesive electrodes have been attached to the leaves of the recently-empowered plant and connected directly to analog inputs of an Arduino Uno.  From there, the text tells us that the signals are mapped to movements of the industrial robot arm that holds the blade.

It’s not clear if the choice of plant is significant, but an unarmed philodendron appears to be otherwise largely innocuous, unless you happen to be a hungry rodent. We hope that there is also a means of disconnecting the power remotely, else this art installation could defend itself indefinitely! (or until it gets thirsty, at least.) We at Hackaday welcome our new leafy overlords.

We have covered the capabilities of plants before, and they can represent a rich seam of research for the home hacker.  They can tell you when they’re thirsty, but can they bend light to their will?  We even held a Plant Communication Hack Chat in 2021.

Continue reading “(Mostly) Harmless Houseplant Wields Machete”

Real Robot One Is… Real

Most of the robot arms we see are cool but little more than toys. Usually, they use RC servos to do motion and that’s great for making some basic motion, but if you want something more industrial and capable, check out [Pavel’s] RR1 — Real Robot One. The beefy arm has six degrees of freedom powered by stepper motors and custom planetary gearboxes. Each joint has an encoder for precise position feedback. The first prototype is already working, as you can see in the video below. Version two is forthcoming.

When you see the thing in action, you can immediately tell it isn’t a toy. There are four NEMA23 steppers and three smaller NEMA17 motors. While there are 3D printed parts, you can see a lot of metal in the build, also. You can see a video of the arm lifting up a 1 kilogram barbell and picking up a refreshing soft drink.

Continue reading “Real Robot One Is… Real”

KachiChan_Sisyphus_RobotArms-On-A-Platform

Robot Repeatedly Rearranges Remnants In The Round

Sisyphus is an art installation by [Kachi Chan] featuring two scales of robots engaged in endless cyclic interaction. Smaller robots build brick arches while a giant robot pushes them down. As [Kachi Chan] says “this robotic system propels a narrative of construction and deconstruction.” The project was awarded honorary mention at the Ars Electronica’s Prix Ars 2022 in the Digital Communities category. Watch the video after the break to see the final concept.

KachiChan_Sisyphus_RobotArms-On-A-Platform_detail-view

[Kachi Chan] developed the installation in pre-visualizations and through a series of prototypes shown in a moody process film, the second video after the break. While the film is quite short on details, you’ll see iterations of the robot arm and computer vision system. According to this article on the project [Kachi Chan] used Cinema 4D to simulate the motion, ROS for control, PincherX150 robotic arms modified with Dynamixel XM 430 & XL430 servo motors, and custom 3D prints.

We’ve covered another type of Sisyphus project, sand tables like this and the Sisyphish. Continue reading “Robot Repeatedly Rearranges Remnants In The Round”

Robot Arm Has The Touch

[Maurizio] built a robot arm, which is always a great accomplishment. But his project includes a very cool touch interface for an Android device that sets it apart from many other similar projects.You can see a very fast summary of the construction in the video below.

The design uses Fusion 360 and there are good explanations of each step in the process. The gripper is adapted from an existing design. Various 3D printed parts make up the wrist, shoulder, elbow, and rotating base.

Continue reading “Robot Arm Has The Touch”

Robot arm in Blender

Animate Your Robot In Blender

You’ve built a robot crammed full of servos and now you settle down for the fun part, programming your new dancing animatronic bear! The pain in your life is just beginning. Imagine that you decide the dancing bear should raise it’s arm. If you simply set a servo position, the motor will slew into place as fast as it can. What you need is an animation, and preferably with smooth acceleration.

You could work through all the math yourself. After half an hour of fiddling with the numbers, the bear is gracefully raising it’s arm like a one armed zombie. And then you realize that the bear has 34 more servos.

render of industrial robot type arm with pedestal, base, upperarm and lowerarm and IK ball

Fortunately for everybody who’s done the above, there’s Blender. It’s all about creating smooth motion for animations and computer graphics. Making robot motion with Blender is, if not easy, at least tolerable. We made a sample project, a 3-axis robot arm to illustrate. It has a non-moving pedestal, rotating base, upper arm, and lower arm. We’ll be animating it first in Blender and then translating the file over to something we can use to drive the servos with a little script.

Now, Blender is notorious for a difficult user interface. The good news is that, with revision 2.9, it moved to a much more normal interface. It still definitely is a large program, with 23 different editors and literally thousands of controls, but we’ll only be using a small subset to make our robot move. We won’t teach you Blender here, because there are thousands of great Blender tutorials online.  You want to focus on animation, and the Humane Rigging series is particularly recommended.

Continue reading “Animate Your Robot In Blender”