Robot Arms Nudge The Hands Of Time In The Strangest Clock

May 9, 2019 by Dan Maloney 8 Comments

We see a lot of clocks here at Hackaday. Digital clocks, retro clocks, lots of Nixie clocks, binary clocks, and clocks that appear to be designed specifically to be unreadable. But this dual-servo kinematic clock is something we haven’t seen yet, and it’s certainly worth a mention.

[mircemk]’s idea is simple and hearkens back to grammar school days when [Teacher] put a large cardboard clock dial on the blackboard and went through the “big hand, little hand” drill. In this case, the static cardboard clock has been replaced by a 3D-printed dial and hands, while a pair of servos linked together by two arms takes the place of the teacher. The video below shows it in action; the joint in the linkage between the two servos has a screw sticking out that can be maneuvered across the clock face to reposition the hands. It’s a little jittery, though; [mircemk] might want to tune the servo loops up a bit or tighten the linkage joints to make things a little smoother.

Even with the shakes, we find it wonderfully weird and hard to stop watching. It reminds us a bit of this luminous plotting clock from a while back – same linkage, different display.

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Robot Arm Is A Fast Learner

January 11, 2019 by Brian McEvoy 3 Comments

Not long ago, machines grew their skills when programmers put their noses to the grindstone and mercilessly attacked those 104 keys. Machine learning is turning some of that around by replacing the typing with humans demonstrating the actions they want the robot to perform. Suddenly, a factory line-worker can be a robot trainer. This is not new, but a robot needs thousands of examples before it is ready to make an attempt. A new paper from researchers at the University of California, Berkeley, are adding the ability to infer so robots can perform after witnessing a task just one time.

A robotic arm with no learning capability can only be told to go to (X,Y,Z), pick up a thing, and drop it off at (X₂, Y₂, Z₂). Many readers have probably done precisely this in school or with a homemade arm. A learning robot generates those coordinates by observing repeated trials and then copies the trainer and saves the keystrokes. This new method can infer that when the trainer picks up a piece of fruit, and drops it in the red bowl, that the robot should make sure the fruit ends up in the red bowl, not just the location where the red bowl was before.

The ability to infer is built from many smaller lessons, like moving to a location, grasping, and releasing and those are trained with regular machine learning, but the inference is the glue that holds it all together. If this sounds like how we teach children or train workers, then you are probably thinking in the right direction.

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Giant Robot Arm Uses Fluid Power, Not Electronics

October 3, 2018 by Dan Maloney 7 Comments

Fair warning that [Freerk Wieringa]’s videos documenting his giant non-electric robot build are long. We’ve only watched the first two episodes and the latest installment so far, all of which are posted after the break. Consider it an investment to watch a metalworking artist undertake an incredible build.

The first video starts with the construction of the upper arm of the robot. Everything is fabricated using simple tools; the most sophisticated tools are a lathe and a TIG welder. As the arm build proceeds we see that there are no electronic controls to be found. Control is through hydraulic cylinders in a master-slave setup; the slave opens a pneumatic valve attached to the elbow of the arm, which moves the lower arm until the valve closes and brings the forelimb to a smooth stop. It’s a very clever way of providing feedback without the usual sensors and microcontrollers. And the hand that goes at the end of the arm is something else, too, with four fingers made from complex linkages, all separately actuated by cylinders of their own. The whole arm looks to be part of a large robot, probably about 3 or 4 meters tall. At least we hope so, and we hope we get to see it by the end of the series.

True, we’ve seen terrifyingly large robots before, but to see one using fluid power for everything is a treat.

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Stepper Motor Robot Arm Has Smooth Moves

January 22, 2018 by Steven Dufresne 17 Comments

[Tobias Kuhn] had watched a YouTube video about a robot arm which used servo motors, and wanted to try making one himself. But he found it hard to get slow or smooth movements out of the servos. Even removing the microcontroller and trying to work with the servo’s driver-IC and potentiometer from an Arduino Nano didn’t get him satisfaction.

Then he found the very affordable 28BYJ-48 stepper motor. After some experimenting, he came up with a smooth moving robot arm with four steppers controlled from an Arduino Mega and A4988 stepper motor drivers. Rather than write a bunch of stepper motor code himself, he installed and ran a four-axis fork of grbl on the Arduino, turning it into a stepper motor controller. One minor hitch was that the A4988 motor drivers are for bipolar stepper motors but 28BYJ-48 steppers are unipolar. Luckily he knew of a very simple hack which our [Brian Benchoff] wrote about for turning a unipolar motor into a bipolar motor.

To tell the robot arm what to do, he built a replica arm with potentiometers in place of the stepper motors. As he manipulates the replica, the values of the potentiometers are read by a Raspberry Pi and some custom Python code which sends the appropriate G-code to the Arduino/grbl controlled robot arm. There’s a bit of a lag but when he moves the replica arm, the robot arm does the same move. See it in action in the video below.

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A Robot Arm For Virtual Beer Pong

December 15, 2017 by Kristina Panos 2 Comments

Leave it to engineering students to redefine partying. [Hyun], [Justin], and [Daniel] have done exactly that for their final project by building a virtually-controlled robotic arm that plays beer pong.

There are two main parts to this build: a sleeve worn by the user, and the robotic arm itself. The sleeve has IMUs at the elbow and wrist and a PIC32 that calculates their respective angles. The sleeve sends angle data to a second PIC32 where it is translated it into PWM signals and sent to the arm.

There’s a pressure sensor wired sleeve-side that’s worn between forefinger and thumb and functions as a release mechanism. You don’t actually have to fling your forearm forward to get the robot to throw, but you can if you want to. The arm itself is built from three micro servos and mounted for stability. The spoon was a compromise. They tried for a while to mimic fingers, but didn’t have enough time to implement grasping and releasing on top of everything else.

Initially, the team wanted wireless communication between the sleeve and the arm. They got it to work with a pair of XBees, but found that RF was only good for short periods of use. Communication is much smoother over UART, which you can see in the video below.

You don’t have to have a machine shop or even a 3-D printer to build a robot arm. Here’s another bot made from scrap wood whose sole purpose is to dunk tea bags.

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A Robot Arm With The Tender Grip Of An Octopus

April 19, 2017 by Jenny List 30 Comments

If you’ve ever experimented with a robot gripper, you’ll know that while it is easy to make an analogue of the human ability to grip between thumb and forefinger, it is extremely difficult to capture the nuances of grip with the benefit of touch feedback to supply only just enough of the force required to grip and hold an object. You as a human can pick up a delicate eggshell without breaking it using the same hand you might use to pick up a baseball or a cricket ball, but making your robot do the same thing is something of an engineering challenge.

The robot gripper is something that has exercised the minds of the folks at Festo, and the solution they have arrived at is as beautiful as it is novel. They have produced a gripper based upon the action of an octopus tentacle, though unlike the muscle of the real thing they’ve created a silicone tube which bends inwards when inflated. Its inner surface is covered with octopus-like suckers, some of which can be activated by a vacuum. The result is a very capable and versatile gripper which due to its soft construction is ideal for use in environments in which robots and humans interact.

They’ve put up a slick video showing the device in action, which we’ve put below the break. Tasks such as gripping a rolled-up magazine or a plastic bottle that would tax more conventional grippers are performed faultlessly.

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Robot Arm From Recyclables

March 30, 2017 by James Hobson 7 Comments

A robot assistant would make the lives of many much easier. Luckily, it’s possible to make one of your own with few fancy materials. The [circuito.io] team demonstrates this by building a robot arm out of recyclables!

With the exception of the electronics — an Arduino, a trio of servo motors, and a joystick — the arm is made almost completely out of salvaged recyclables: scrap wood, a plastic bottle, bits of plastic string and a spring. Oh, and — demonstrating yet another use for those multi-talented tubers — a potato acts as a counterweight.

Instead of using screws or glue, these hackers used string made from a plastic bottle as a form of heat shrink wrap to bind the parts of the arm together. The gripper has only one pivoting claw for greater strength, and the spring snaps it open once released. Behold: your tea-bag dunking assistant.