Inspired by Mr Chicken’s Animatronic Raven, I created set out to create an animatronic crow of my own. At time of writing as well as when I was researching for the project, his DIY kit for it is sold out.

Prototype

For the outer shell of the shell, Mr Chicken uses a vacuum formed shell to minimize weight without sacrificing detail or strength. Unfortunately, not only did I not have access to a vacuum former, I also did not have a 3D model let alone a buck to form over. As my 3D sculpting skills were not quite up to the task, I searched online and found this model by YahooJAPAN on Thingiverse. Ideally, I would have used a model that was already articulated, but I could not find any so I would have to slice up the model myself.

At the time, I wanted to make this model as accessible to as many people as possible which meant 3D printing as much of it as possible and reducing specialty hardware to buy. For the neck, I designed a universal joint which was surprisingly easy to print and effective and instead of screws, the servo motors were fixed in place with zipties which turned out incredibly clean. The head pan and tilt uses paperclip linkages that mimic Mr Chicken‘s design which some slight alterations at the attachment points to accommodate print orientations. Unfortunately, many of the parts require some support material but I kept overhangs to a minimum. There are 4 servos and therefore Degrees of Freedom in my design:

• Jaw
• Head Pan
• Head Tilt
• Hip

While I did consider adding a 5th one for wings flapping, I was unable to design a satisfactory mechanism.

Final? Version

Having completed a prototype, I set out to find a more realistic body for the animatronic skeleton I designed. Searching online, I found out that taxidermy is incredibly expensive. I also found out that fake dead crows are a common product people buy and sell for scaring off real ones. While making a bespoke body from scratch may have produced a more realistic end product, this route was too convenient to ignore. Upon delivery, I personally found that the crow did not hold up to close inspection but my mom kept getting frightened every time she peered into my room so it seemed promising. Peeling feathers off to reuse and carving through glue and plastic was a bit of an ordeal but I managed to fit all the mechanisms and controllers inside. When I tried to put the feathers back where they were supposed to be, since the head had to accommodate a jaw, they did not sit as well as they used to. The crow looks much scruffier than it used to.

To make the design portable, I modified the feet to mimic a GoPro so that I could use a shoulder harness to carry the crow on my shoulder. This was not very comfortable as the bird is slightly unbalanced but is still doable. I had some tire balancing weights from a different project and adding them to the tail section helped a lot. After writing a script to make it periodically gawk and squawk in random directions, I was able to make it completely portable with a power bank that also fit inside the shell.

With all the added weight, the hip servo was unable to properly lift the body of the crow. Mr Chicken solves the weight problem using much heavier servos than my MG90S’s as well as a heavier spring than my elastic bands. However, after some experimentation, I found out that a 3D printed worm drive mechanism is very feasible and practical. Despite the 180 degree range of the servo, the body is able to swing up and down a good 20 degrees with little effort. Furthermore, due to the nature of worm drives, there’s no need for an elastic band to help hold positions.

After finalising my design, I reprinted all the insides in black PLA and assembled the crow for the last time (at least for now).

Overall, this project has taught me a lot about the feasibility of 3D printed mechanisms and limitations of trying to adapt other people(who are not collaborators)’s designs into custom animatronics. While I feel that I have enough experience robotics design, I hope to one day revisit this project with more propmaking skills to create a more complete looking animatronic.