Rudolph used to be Santa’s favourite reindeer. But then he got old, flatulent and rude, so Santa had to let him go. These days Rudolph — or “Rude-olph” as he’s now known — earns a crust by entertaining customers in pubs across Scotland.
Rude-olph is our latest electronic installation/stunt for Scotland’s most popular beer brand, Tennent’s. He was designed and built from scratch in-house, using the artists, makers, hardware and software engineers that we have at Bright Signals. And it was all done in an incredibly short timeframe: just 10 days from getting the project green-lit through to his first public appearance.
My starting point with Rude-olph was to build a development mule. This was knocked together in an afternoon using some spare CLS timber we had lying around in the workshop and a couple of standard servo motors hooked up to a Raspberry Pi.
I decided to base his neck movement around a flexible spine to give a more realistic animal movement than you’d get from a fixed hinge or pivot. This neck movement is driven by a pulley and servo setup which, on my prototype, actually uses a small jam jar as the pulley mechanism.
The prototype worked remarkably well, the only real limitation being the slightly imperfect movement you get when controlling servos directly from the Pi’s GPIO pins. That issue was resolved by offloading servo duties to an UltraBorg (piborg.org) which arrived overnight from the fab folks at The Pi Hut.
With the movement prototyped, it was time to move onto the full-scale build…
For the main neck movement we opted for a heavy duty 270° servo from DF Robot, mated to stainless steel cables that run the length of Rudy’s neck. This combo gives us a good degree of movement whilst retaining the full 15kg-cm torque of the metal geared servo.
We wanted to keep Rudy as much of a ‘standalone’ unit as possible, so we packed the Raspberry Pi, servos, microphone, speakers and other components into the shield that Rudy is mounted to. To give the shield as much internal space as possible, whilst at the same time minimising weight and thickness from the wall, we designed and laser cut a custom shield out of poplar plywood. Over a dozen pieces slot together to form a shield that looks solid, but provides all the space and cable management required for Rudy’s electronics. Once the mechanical construction was locked down we moved onto the appearance.
Our in-house artist used faux fur and paint to give Rudy his final look, which exceeded all of our expectations. The one remaining challenge was his eyes: the ‘realistic’ reindeer eyes we sourced from a taxidermy wholesaler were a bit gruesome, so we made a last minute dash to our local toy shop — fortunately they had some stuffed toys that were able to donate their eyes to our project. (Yes, that was me standing in a toy shop at 9pm with a ruler, measuring the eyes on various plushies.)
Rude-olph’s software is entirely web-based, allowing us to control every aspect of his movement and vocabulary from a web browser — either on a laptop or smartphone. All of the software was built and tested on the development mule while the rest of the team worked on the physical appearance of the full-size version.
Rudy has three software operating modes that we can switch between depending on what he’s doing at the time:
- Film set mode
In this mode he’s under full manual control. Latency is virtually zero, thanks to the fact that the web server is the same script that’s controlling the UltraBorg servo board. This allows us to follow director and actor cues in real time, rather than performing predefined moves.
- Voice actor mode
For the press launch of Rude-olph we wanted to have a comedian voicing him live, so we created a two-way audio feed and some simple software to allow us to syncronise Rudy’s mouth movements to the comedian’s chat.
- Soundboard mode
This is Rude-olph’s main mode when he’s out on tour around the pubs of Scotland. Operators can choose from over 140 stock phrases and songs, all organised by topic and target audience. Automatic waveform analysis allows us to precisely synchronise these sound files to mouth movements from the servo.
The UltraBorg proved invaluable here too — thanks to its intelligent limit configuration, we could switch back and forth between the development mule and the full-scale reindeer without changing any of the values in software (essentially telling the servos to move from 0 to 100% and trusting them to know what that means depending on context).
Lights were switched from the Pi’s GPIO, but powered from the UltraBorg, leaving the Pi’s original power supply ‘clean’ for a single duty.
Our web interface also provides a video and audio feed from Rudy, allowing the operator to see and hear what people are saying to the reindeer. It all works over wi-fi, allowing the operator to tuck themselves out of sight of the public.
The launch video
Here’s the launch video we shot for Rude-olph, all manually controlled in ‘film set mode’.
Rude-olph is on tour across Scotland throughout December. Following his Glasgow launch, he’ll be in Edinburgh, Dundee and Aberdeen, running right through until 30th December.