K9

Yes Master!

 K9
Dec 312008
 

K-9, the robotic companion to the Fourth Doctor, was my first project and I learned a lot from making him. Since the BBC had long ago released plans for K-9, I thought that this would be an easy project to do. I was SO wrong. It was much harder to do than I imagined. I found the plans that the BBC released. Sadly several dimensions were missing.
K-9 on patrol in my hallway

10 Things I would do differently next time

  1. Use a better amplifier.
  2. Add a method of sensing people to start interaction.
  3. Use servos to control the radar (ears), gun (nose) and wagging tail.
  4. Build the whole body from lighter materials.
  5. Change the head (in the plans issued by the BBC, the dimensions for the head are incorrect).
  6. Use an ISD2560 IC for the speech or similar IC.
  7. Remote control drive.
  8. Make the electronics accessible via a panel on the side of the body.
  9. Use PCBs instead of using stripboard for the electronic circuits.
  10. Make the electronics more modular.

I did not initially make a list of features that make it recognizable as a character. But if I had it would be like this.

  • Speech
  • Glowing eyes
  • Retractable sensor
  • Retractable gun in nose
  • Printed paper strip out of mouth
  • Oscillating dish ears
  • Tilting head
  • Television screen on side of dog
  • Wagging tail
  • Computer on back
  • Side panel removable
  • Remote control drive
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Adding life

 K9
Jan 012008
 

After playing around with some battery operated drill motors I felt that they were too long to fit inside K-9′s body
I instead used 2 electric window up/down motors from a car.

The H-bridge worked fine however the weight of the body and the wheels being slightly misaligned made the wheels rub on the frame. When I powered it up the first 3 or 4 times K-9 shot across the floor proudly.

As they rubbed it got worse until the fuses started blowing. I gave up trying to fix this because it was just too difficult to access the motors each time.

I did not really consider things being accessible

Flashing computer

For the ‘computer’ that sits on K-9′s back I purchased a large calculator that was the correct dimension and modified it to look somewhat authentic.

The lights that flash are LED’s controlled by a Pic16F84A programmed with JAL.

Basically it is the ‘Knight Rider style’ sample program that comes with JAL but with some slight modifications and some fancy wiring.

The head

The head was assembled last,
K-9 has a gun that comes out just below his nose. I had the gun moving back and forth but no way to fit the assembly in the head, plus the motor driver IC was getting hot, so I glued it in place.

K-9′s ears are two radar dishes that oscillate back and forth. I purchased some surplus stepper motors which would fit side by side inside the head. I then created a circuit to make them oscillate back and forth. Once powered up, the circuit worked marvelously, almost totally silent, and the ears rotated back and forth very smoothly. I noticed current consumption of the stepper motors was quite high.

Here are the ears moving

Speech

I had someone do the K-9 voice and modified the files with Audacity, which then I burned to a CD. I had a CD player that was controlled by a Pic16F84A IC for Play, Stop, FF, etc.
Here is where timing became an issue (and thus the down side of using this method).
As the CD does not provide feedback on what is happening, you cannot tell if it is playing or not or even which track is playing. I so everything had to restart from a reference point for each track, each track was exactly the same length and every thing was based on timing and then, when finished playing, back to that reference point.

Overall this is not the best way to control speech or music.

 

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Putting K9 together

 K9
Jan 012008
 
Putting K9 together

A cardboard mock up of the head The real head painted with primer The body made from hardboard before painting Primer added to body Side view all painted Body front/side view 0   

K-9 Body

 K9
Jan 012008
 
K-9 Body

The body and head were based on the plans that the BBC released. A piece of plywood approx 29″ x 18″ is the base everything sits on. Then I made a frame that was the size of the body and the skin sides were cut from hardboard and glued to the frame Building the body [...]

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