Smooth Servo Motion For Lifelike Animatronics

September 3, 2021 by Danie Conradie 10 Comments

Building an animatronic robot is one thing, but animating it in a lifelike fashion is a completely different challenge. Hobby servos are cheap and popular for animatronics, but just letting it move at max speed isn’t particularly lifelike. In the video after the break, [James Bruton] demonstrates how to achieve natural motion with a simple animatronic head and a few extra lines of code.

Very little natural body movement happens at a constant speed, it’s always accelerating or decelerating. When we move our heads to look at something around us, our neck muscles accelerate our head sharply in the chosen direction and then slows down gradually as it reaches its endpoint. To do this in Arduino/C code, a new intermediate position for the servo is specified for each main loop until it reaches the final position. The intermediate value is the sum of 95% of the current position, and 5% of the target position. This gives the effect of the natural motion described above. The ratios can be changed to suit the desired speed.

The delay function is usually one of the first timing mechanisms that new Arduino programmers learn about, but it’s not suited for this application, especially when you’re controlling multiple servos simultaneously. Instead, the millis function is used to keep track of the system clock in the main loop, which fires the position update commands at the specified intervals. Adafruit wrote an excellent tutorial on this method of multitasking, which [James] based his code on. Of course, this should be old news to anyone who has been doing embedded programming for a while, but it’s an excellent introduction for newcomers.

Like most of [James]’s projects, all the code and CAD files are open source and available on GitHub. His projects make regular appearances here on Hackaday, like his mono-wheel balancing robot and mechanically multiplexed flip-dot display.

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Disney Imagineering’s “Project Kiwi” Bears Groot

April 26, 2021 by Zach Zeman 31 Comments

Some days, we might be forgiven for believing Boston Dynamics has cornered the market on walking robots. They (and other players) are making incredible progress in their field, but three years ago Disney, trying to create autonomous, free-walking robotic actors for some of their more diminutive film characters, found none of the existing platforms were appropriate. So they set their Imagineering department to work on “Project Kiwi”, and we are now seeing the fruits of those efforts.

Research on bipedal robots has amassed over the years, and as the saying goes, if these Imagineers saw further it was by standing on the shoulders of larger robotic platforms. However, the Project Kiwi designers have made a laundry list of innovations in their process of miniaturization, from the “marrow conduit” cooling system which forces air through hollow bones, to gearing that allows actuators to share motors even across joints. The electronics are distributed around the skeleton on individual PCBs with ribbon flex cables to reduce wiring, and almost every component is custom fabricated to meet the complex size and weight requirements.

Even in this early prototype, Disney’s roots in life-like animatronics are evident. Groot’s movements are emotive, if a bit careful, and software can express a variety of personalities through his gaits and postures. The eyes and face are as expressive as we’ve come to expect (though a keen eye for seams puts off some definite Westworld vibes). Reportedly, this version can handle gentle shoves and contact, but we do spot a safety cable still attached to the head. So there’s probably some way to go before we’ll see this interacting with the general public in a park.

Disney’s Imagineering department has been doing some amazing work with robotics and they continue to make significant innovations in the more traditional fields of animatronics. It certainly looks like one of the coolest places to work right now, and now we’re itching to build our own bipedal friends to play with.

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Spherical Quadruped Arduino Robot

May 21, 2020 by Orlando Hoilett 9 Comments

[Greg06] started learning electronics the same way most of us did: buy a few kits, read a few tutorials, and try your hardest to put a few things together. Sound familiar? After a while, you noticed your skills started increasing, and your comfort level with different projects improved as well. Eventually, you try your hand at making your own custom projects and publishing your own tutorials.

Few are lucky to have a first-project as elaborate as [Greg06’s] quadruped robot. We don’t know about you, but for some of us, we were satisfied with blinking two LEDs instead of just one.

[Greg06’s] robot has a quadruped based, housed within a 3D printed spherical body. The legs are retractable and are actuated by tiny servo motors inside the body. [Greg06] even included an ultrasonic distance sensor for the obstacle avoidance mechanism. Honestly, if it weren’t for the ultrasonic distance sensor protruding from the spherical body, you might think that the entire robot was just a little Wiffle ball. This reminds us of another design we’ve seen before.

If that weren’t enough, the spherical head can rotate, widening the range of the ultrasonic distance sensor and obstacle avoidance mechanism. This is accomplished by attaching another servo motor to the head.

Pretty neat design if you ask us. Definitely one of the coolest quadrupeds we’ve seen.

Use Movie Tools To Make Your Robot Move Like Movie Robots

May 23, 2019 by Roger Cheng 6 Comments

Robots of the entertainment industry are given life by character animation, where the goal is to emotionally connect with the audience to tell a story. In comparison, real-world robot movement design focus more on managing physical limitations like sensor accuracy and power management. Tools for robot control are thus more likely to resemble engineering control consoles and not artistic character animation tools. When the goal is to build expressive physical robots, we’ll need tools like ROBiTS project to bridge the two worlds.

As an exhibitor at Maker Faire Bay Area 2019, this group showed off their first demo: a plugin to Autodesk Maya that translate joint movements into digital pulses controlling standard RC servos. Maya can import the same STL files fed to 3D printers, easily creating a digital representation of a robot. Animators skilled in Maya can then use all the tools they are familiar with, working in full context of a robot’s structure in the digital world. This will be a far more productive workflow for animation artists versus manipulating a long flat list of unintuitive slider controls or writing code by hand.

Of course, a virtual world offers some freedoms that are not available in the physical world. Real parts are not allowed to intersect, for one, and then there are other pesky physical limitations like momentum and center of gravity. Forgetting to account for them results in a robot that falls over! One of the follow-up projects on their to-do list is a bridge in the other direction: bringing physical world sensor like an IMU into digital representations in Maya.

We look forward to seeing more results on their YouTube channel. They join the ranks of other animated robots at Maker Faire and a promising addition to the toolbox for robot animation from Disney Research’s kinetic wires to Billy Whiskers who linked servos to Adobe Animate.

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Laser Cut Cardboard Robot Construction Kit Eases Learning And Play

October 18, 2018 by Donald Papp No comments

It has never been easier to put a microcontroller and other electronics into a simple project, and that has tremendous learning potential. But when it comes to mechanical build elements like enclosures, frames, and connectors, things haven’t quite kept the same pace. It’s easier to source economical servos, motors, and microcontroller boards than it is to arrange for other robot parts that allow for cheap and accessible customization and experimentation.

That’s where [Andy Forest] comes in with the Laser Cut Cardboard Robot Construction Kit, which started at STEAMLabs, a non-profit community makerspace in Toronto. The design makes modular frames, enclosures, and basic hardware out of laser-cut corrugated cardboard. It’s an economical and effective method of creating the mechanical elements needed for creating robots and animatronics while still allowing easy customizing. The sheets have punch-out sections for plastic straws, chopstick axles, SG90 servo motors, and of course, anything that’s missing can be easily added with hot glue or cut out with a knife. In addition to the designs being open sourced, there is also an activity guide for educators that gives visual examples of different ways to use everything.

Cardboard makes a great prototyping material, but what makes the whole project sing is the way the designs allow for easy modification and play while being easy to source and produce.

Animatronic Puppet Takes Cues From Animation Software

July 27, 2018 by Steven Dufresne 8 Comments

Lip syncing for computer animated characters has long been simplified. You draw a set of lip shapes for vowels and other sounds your character makes and let the computer interpolate how to go from one shape to the next. But with physical, real world puppets, all those movements have to be done manually, frame-by-frame. Or do they?

Stop motion animator and maker/hacker [James Wilkinson] is working on a project involving a real-world furry cat character called Billy Whiskers and decided that Billy’s lips would be moved one frame at a time using servo motors under computer control while [James] moves the rest of the body manually.

He toyed around with a number of approaches for making the lip mechanism before coming up with one that worked the way he wanted. The lips are shaped using guitar wire soldered to other wires going to servos further back in the head. Altogether there are four servos for the lips and one more for the jaw. There isn’t much sideways movement but it does enough and lets the brain fill in the rest.

On the software side, he borrows heavily from the tools used for lip syncing computer-drawn characters. He created virtual versions of the five servo motors in Adobe Animate and manipulates them to define the different lip shapes. Animate then does the interpolation between the different shapes, producing the servo positions needed for each frame. He uses an AS3 script to send those positions off to an Arduino. An Arduino sketch then uses the Firmata library to receive the positions and move the servos. The result is entirely convincing as you can see in the trailer below. We’ve also included a video which summarizes the iterations he went through to get to the finished Billy Whiskers or just check out his detailed website.

[Jame’s] work shows that there many ways to do stop motion animation, perhaps a part of what makes it so much fun. One of those ways is to 3D print a separate object for each character shape. Another is to make paper cutouts and move them around, which is what [Terry Gilliam] did for the Monty Python movies. And then there’s what many of us did when we first got our hands on a camera, move random objects around on our parent’s kitchen table and shoot them one frame at a time.

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R.O.B. Gets A Proper RC Resurrection

March 3, 2018 by Sonya Vasquez 3 Comments

More than 30 years ago, Nintendo’s R.O.B graced toy shelves, helping usher in an age of video games that is here to stay. For the few of us lucky to own one of these relics, we’ll find that R.O.B’s internal mechanisms that drive the arms and neck movements are just begging to be modified. That’s exactly what [Kenny Storm] did, installing a few continuous-rotation servos to give R.O.B a new mobile life of its own.

The original R.O.B featured a surprisingly intricate gearbox configuration embedded inside the shoulders for both up-and-down shoulder movement and hand-pinching. (For a more detailed investigation on the internals of the original hardware, have a look at this teardown.) This hack is sparsely documented, but from what we can gather, the mobile R.O.B uses all three existing degrees of freedom that the original supported while furthermore adding mobility with continuous rotation servos.

Glancing at the dates from this forum post, this find is almost 8 years old. Age is never a dealbreaker here, though, as the sheer quaintness of this hack will surely stand the test of time. Watching R.O.B take up a presence with mobility on this desk hearkens back to our childhood mysticism of unboxing this companion with our Nintendo when we were children. Finally (shameless plug!), if you’re just as excited as the author at the chance of seeing R.O.B back on your shelf with at-home-manufacturing techniques, have a go at printing my 1:1 scale R.O.B head replica.

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