If you grew up in the 1980s in the United States, you undoubtedly remember a toy called “Teddy Ruxpin.” Your feelings of this bear likely range from fondness, such as happy memories of it “reading” you a story; dread, possibly fear; or curiosity about how it worked. Maybe you even felt some envy at the time if you didn't have one, likely replaced years later by curiosity about what made you want one.
Nearly 30 years later, you might again think upon that doll and realize that with modern microcontrollers, like the Arduino, this doll could be made into something different and debatably better than what it was originally intended for. Fortunately, if you'd like to start tearing into one, you can build on the excellent work of others.
Mechanically, the bear is extremely simple, using one servo to control both the eyes and the mouth. Although I haven't personally disassembled one, I would guess that here is a mechanical linkage (possibly a cam) that keeps the eyes open while the servo travels through a certain range. This would allow it to actuate the mouth to “read” the story while the eyes stare creepily ahead until the servo was fully lowered.
To get to the electronic goodies, you'll have to remove a flap on the back of the bear's shirt. The tape player then needs to be removed to get to the three servo wires inside the bear's body cavity. There are also two apparent power wired in this space, but if you're going to replace its centrally-located “brain” with your own controller, these likely won't be needed. There are some more pictures on wgz.org that help illustrate what is needed here. The other three wires can then be hooked up to your own controller solution for whatever mischief you'd like to cause with it. An Arduino, Raspberry Pi, or even a pyMCU come to mind.
This article on Ars Technica uses an Arduino as a method for a computer to “possess” the bear, and sync up mouth movements with the Windows voice synthesizer. If one wanted to go even further, a Raspberry Pi would seem like an idea candidate for a stand-alone system.
Going even further, I'd love to see one with servos embedded in the shoulders to allow for some crude arm movement, or maybe something to actuate the eyes. LEDs might be an even better solution to allow them to glow at opportune times. Of course, that doesn't even get into the possibility of using some sort of sensors for feedback. Maybe a passive infrared sensor could be used to surprise unsuspecting passers-by. It's not too early to think about your Halloween display this year!
Taking a different tack, maybe you'd rather see 80 of them talking in sequence. Maybe a Bluetooth or WiFi connection could be used for something similar if a stand-alone system was devised.
It seems like a strange thing for kids to want today, but it was the best selling toy of 1985-1986. On the other hand, maybe I just don't possess or understand the psychology of a 5-year-old anymore. This is probably a good thing. Finally, if you're wondering what a “Teddy Ruxpin” is, or just want a reminder, check out this YouTube channel for a sampling of what this little animatronic bear is all about.
— Jeremy Cook is a manufacturing engineer with 10 years experience and has a BSME from Clemson University. In his spare time he enjoys writing for DIYtripods.com.