K9 has been a favourite in the cult hit Doctor Who. Fergus has built many robot replicas, and this is his second K9 replica. It's a labour of love.

Taken as a likeness from the show-featured K9, this replica is impressive and interactive. We caught up with Fergus, its maker, to see what went into making this awesome replica.

Your replica K9 robot is great - are you a big Dr Who fan?

Dr Who really only got my attention when Billie Piper and David Tennant were in it. My interest grew when I saw K9 and Cybermen in other episodes. I may have also painted a sliding door as a TARDIS... purely from boredom, of course! 

What was your original intention with K9 - just a bit of fun, or was it to serve a specific purpose?

I had previously built a full size K9 using plans from a robot builders group. A change of vehicle caused me some transportation issues and other factors prompted me to build a scale model. Whilst building the mini K9 I was invited by Jaycar to bring my Replica R2D2 to their Oz ComicCon stand in Sydney, and collect donations for the Westmead Children’s hospital. This made me reevaluate my K9 build criteria. I opted to use as much hardware that would be available in their Arduino stock, to demonstrate its practicality. I had seen various toys with interactive platforms and a commercially built mini R/C K9, which had little or no functionality. 

There’s nothing like having a robot too big for your car to cause you to rethink your plans! Since your K9 is much more than just a radio controlled dog robot, tell us a little about K9’s capabilities.

K9 can be controlled remotely by using an Android app via a Bluetooth module for its driving function. There is an onboard 4D systems module connected to an Arduino that has been programmed to select K9 ear and tail movements, and to also display animations.

Nice one! There’s so much more to it than just a screen and Arduino though. How did you make K9’s body?

K9 is made from white acrylic sheet of varying thicknesses. Each part is marked out and cut with a blade. Parts are bonded together with a solvent, which results in a solid fused part. Scaling was difficult due to the size of commercial switches and display screen availability. Panel angles had to be modified to allow all the internals to fit and be accessed when required. The head internals were a trial and error, built to make the mechanisms work in very limited space. Its final look was achieved by paint shading and “weathering” so as to provide an extra degree of realism.

The paintwork is great, and does have a fantastic metallic look to it! Did you go through much trial and error with the first build?

I don’t use CAD or CNC and therefore there are a number of parts that were remade during the project. Fitting servos in confined spaces resulted in access and functional challenges during the build. The biggest collection of “spare parts” are from redesigned tail mechanism pieces that had to be assembled in a specific order, along with the first head frame that simply couldn’t contain functional mechanisms.

"He's my 2nd best friend. Aren't you K-9?"

That’s some real complexity to handle, without the use of CNC or Laser - well done! All that gear must take some juice though - how is K9 powered?

As space and battery longevity was a premium, I selected a 30C series LiFe 4200, 13.2V battery. Under full systems use the battery can run for about two hours. Without drive motion it will run for up to seven hours. In tank mode, an L298 dual motor board runs the drive wheels.

That’s some excellent battery life! Tell us about the touchscreen; what functions does it perform?

The 4D systems module has been programmed to display animations and select Arduino sketches to control K9 ear and tail movements. Two servos combined, operate the tail mechanism, two servos for the individual dog ears, one servo for the extendable “laser” nose gun, a drive motor controller board, 14 panel LEDs, and two Jumbo LED eyes. The main switch is a three position switch where one selection provides full functionality, the other offers full controls but no drive motor availability. This was to ensure no accidental movement whilst on a display counter.

On boot-up, the 4D systems screen displays Dr Who images from Google, which are preloaded into its microSD card. Once up and running, pressing the front of the screen allows a sub menu for the head controls to be selected. Four selections are displayed for the ears: scan, patrol, normal and stop. Part of this sequencing sees the nose gun extend and the laser (LED) illuminate, then retract. The screen reverts to displayed images that change as per programmed timing. Touching the screen again brings you back to the menu. Touching the screen again selects the tail mechanism functions. It was decided to name them Rotate, Wiggle, Waggle and Stop. 

Autonomous self-drive and object avoidance could be an upgrade with a future expansion. 

We love the “nose laser”, it’s very cool! The entire build has been well thought out with some very complex servo configurations, even if it’s just for comedic effect. What unexpected challenges did you face while creating K9?

The biggest challenges were timing - the required completion date for Oz Comic-Con was way ahead of our original build-time plans; and the task of making this scaled down version look acceptable.

There’s nothing like a deadline to make things happen (we know a thing or two about deadlines too!). If you had your time again and were looking to build K9 version 3.0, what would you change?

I would put more distance between the two tank drive mode wheels and the rear caster, as it’s currently very sensitive with the Bluetooth app. This could be easily changed to standard R/C setup, but it would have less Arduino functionality as a result.

That’s true. An R/C robot dog is still cool, but not really what you set out to achieve. What are you working on now?

I have a number of projects to complete and others to start. My full size scratch-build Star Wars chopper Droid needs its drive train “refined” for more reliability and stability. I may even work on the mini K9 ticker tape printer that I originally intended to include in its build. I also have to do some maintenance and repairs on my R2D2 for a “Make A Wish” event.

Wow - sounds like you have quite a number of projects on the go, and for a great cause too! Be sure to let us know when your next one is complete. Thanks for taking us through your K9 replica!