I built my first K9 back many years ago when I was at University as part of an Arts project. A few years ago I met a number of the creators of the Dr Who K9 robot and after talking to them about my other robots I had build they encouraged me to build my own K9, or rather my take on the k9 design. I have always like the K9 character, however, I never really got around to building one as the build itself was a bit to simple and would not present a real challenge. This changed a number of years ago and my K9 build was created.
He is built entirely from MDF although the chassis is metal. The drive system was from two electric scooters running at 24v. Three 12v 12Amp SLA batteries power the drive and 12v electronics. He is designed so that the top section and lower section can be removed, the drive in the lower section and all the main electronics in the upper system. I very recently completely overhauled the electronics system and created a removable side panel which gives much better access to the new electronics I have added including new battery monitors and radio gear. I decided to based my K9 on the original designs provided to me via a BBC designer, however, I did have to change them slightly to accommodate the top removable section and slightly wider head to fit the mechanical ear system.
k9's head is operated via an curved alloy bar attached to a car central locking solenoid which in turn is controlled via an RF switch.
His ears are driven via 360 degree servos linked together by a couple of lego technic gears glued in place. The nose and tongue are again controlled via servos on a simple rack and pinion system, made again from lego technic.
There are of course lots of LED's. The under body LED's are sound activated, the main eyes fixed red LED's and the rest sound reactive.
He has a built in 'fart" spray which is compressed gas trigger via an RF switch. The water spray exists through is nose sucker. On board sounds are stored on an MP3 trigger board and triggered by the RF switch.
Considering how many years ago I made my K9 I am surprised that he is still going strong. He is very popular at charity events and the kids seem far more interested in him that any of my Star Wars Droids.
One thing that had always caused me problems at public events is that people want to stroke K9 and doing so would cause his ears to all off or break. I eventually solved this by making flexible ears, ones that would fold back on his head when stroked. To achieve this all I did was add small pieces of flexible plastic tubing between the ear servo connector rod and the ear , this way the top section could flex and not fall of when stroked.
I also changed the wagging tail to make it more resiliant as at most events it would get snapped. The tail to is now flexible and connected to a quick release mechanism on the drive servo so if it is pulled will easily pull away without breaking anything.
What was really nice was that eventually I met up again with Matt Urvine and John Leason, the maker and Voice of K9 and both endorsed my work by signing K9, certainly the only two signatures I would ever allow on this build.
As I mentioned earlier K9 has just received a 2012 make over getting a new electronics system and a few extra gadgets. He will never get repainted as he now has so many real bumps and scrapes from all the events that I could never remove these. When I eventually catch up with John Leason again I will ask John can he record me some unique K9 sounds, this should complete this build.
To help any builders out their who might like to build their own K9, I have included some PDF plan files. Please be aware that plans like this were originally provided by the BBC to help support amateur builders and models built from these plans should not be used for commercial purposes. I thought I would share this as I feel it is important that we honour there requests so they will keep releasing new plans as they create new creations. I also have Dalek plans if anyone is interested.