Dragon

12 September 2014

Some more information on that brown board. We made it following this tutorial. We purchased a number of MCP23017 integrated circuits (5 for $10) and only need one per board. Depending on where you connect the data board will depend on which port address the board accepts from the same 2 data pins from the arduino. Nifty.

We use for pins from the arduino to control the board, earth, power, clock and data. The data channel sends a byte to either the first port or the second port, where each byte turns a pin on or off on the chip. Each of these pins is connected to the relay via a ribbon cable and turns a relay on or off. It’s as simple as sending 0b00000001 to port A to turn the first relay on.

The circuit board also shares a common earth and power to the relay. All of these run at 5 volts (for the positive).

The relay board runs off 12 volts, so can accept a voltage quite nicely from the main battery of the dragon (it has two huge 12 volt batteries in it in series – 12 volts to run most of it, 24 volts for the drive motor). The relay steps the 12 volts down to 5 volts and powers the whole thing.

In this way, the input from the joystick (green) can be sent to arduino (blue) to interpret. It then sends two bytes of data to the circuit board (brown), which instructs the relay board (also blue). Two relays are used to control the direction of each of the linear actuators.

Relay 1 = negative (default) & Relay 2 = negative (default) == Sum total is no differential in voltage, so nothing happens.

Port A = 0b00000000 (0b mean binary, which is easier to visualise for on off switches and the program allows for us to use that – so why not?)

If Relay 1 = positive & Relay 2 = negative == Sum total is 12 volt contract, which is a 65 NM (or kilogram) pull

Part A = 0b00000001

If Relay 2 = negative & Relay 2 = positive == Sum total is 12 volt push, which is 60 NM (or kilogram) push

Port A = 0b00000010

If a mistake is made: Relay 1 = positive & Relay 2 = Positive == Sum total is no differential in voltage, so nothing happens

Port A = 0b00000011

We need to be mindful of the load capacity of the relays. That is, they can operate for 1 out of every 10 minutes to ensure they don’t over heat. As the neck won’t be constantly moving, this shouldn’t be a problem. This capacity may be increased with extra cooling, but lets cross that bridge only if we have to!

 

11 September 2014

Electronics for the neck control are complete.

 

The image on the left is the joystick controller attached to the top of the arduino – it just plugs right in. The arduino is the blue thing under the green joystick. The blue cable attaches the ardino to the brown board at the back. The brown board is an IO (input output) expansion board for the arduino. The ribbon cable connects the expansion board to the relay board in the centre picture.

The relay board has 16 relays (remote controlled on/off switches for voltages greater than 5 v). We use two relay’s to control each linear actuator (pictures on the left).

Each relay has two positions and three wires. The Central wire is what is connected to either the Left or the Right. We connect negative to both Lefts and positive to both Rights. The default position is that Left is connected to Central (off), and that can be switched to Right (on). The linear actuator is connected to the centre of Relay 1 and the centre of Relay 2. By default then, both wires of the actuator are negative, which means do nothing. If both relays are turned on, then both wires are now positive, which means do nothing. Only when one is on and the other is off will it do something, and depending on if Relay 1 = on, Relay 2 = off == extend, or Relay 1 = off, Relay 2 = on == contract.

Easy.

So we have 5 small X movement neck relays and one big Y movement neck relay.

The Joystick is programmed to control the X relays for left right movement and the Y relay for up down movement. The X axis is progressive – a little nudge moves the head and not the rest, a bigger one moves both the head and the next relay down, a hard nudge moves them all. The relays automatically trip out when they hit their limit.

The Y axis is hard on or hard off because there is only one of them and I don’t want to accidentally trigger it.

Any time the joystick is centred (self centres when turned off), the relays stop where they are. It has full range of motion such that it can trigger both X and Y movements at the same time (diagonals) or just X or just Y. If you think about it, I can do a full down and left move, then a full up and slight right move. This will initially shift all the neck left and down a bit, then have a slight rise and head move to the right.

Each button on the joystick board will have a different function. One will control the eye-lights, another will control the pilot and two will control the flame.

It’s going to be epic.

Each of the relays has a reinforcing bracket – because I don’t trust the aluminium body to be strong enough. I have one more to make.

2 August 2014

Electronics have arrived… so exciting. Have started playing with programming the control board, however the interface between that and the relay board are… limited. Need to build an extra circuit to enable enough input output signals from the control board to the relay board. That will make the programming a bit trickier… oh gosh darn  :-)

A longer range plan is to translate a 3-5 volt variation (from the control board) into a 9 to 15 volt variation (to control the LEDs).

7 July 2014

The neck vertebrae have now been re-constructed with solid 25 mm steal tube, inter-vertebra connectors have also been drilled (thanks Clare) and welded. Next step is the bracket for the linear actuators.

Parts have been purchased online for the electronics to manipulate the neck. Waiting for them to arrive. Each neck joint will take two relays to power (Left and Right direction). The arduino board is going to handle the logic circuits to ensure the joystick control manipulates the neck in gradual and sudden movements.

The new gear set has been added to the existing gearbox/differential and to the new 500 watt motor. I’m feeling the power! This should give me a maximum ideal speed of about 15 km/h, however I expect I will get a more realistic speed of 8 km/h at top gear and probably about 1.5 – 2 km/h on low gear or reverse. I’m pretty happy with that likelihood and can’t wait to get it plugged in and tested. I have created a slide tension bracket for the motor to attach to the gear housing wall, however placement of the bracket is going to be crucial to ensure the cogs line up.

I’m having thought about how to reconstruct the head to give multiple flame options I think I will have a single jet coming from the mouth and twin jets from the nostrils The single jet will go further than the twins, and it will be a selector of one, or the other, or both. A separate gas bottle and line will power the pilot flame. I’m going to need a separate data cable just for the flame options! Fortunately the head cabling has a plug that allows me to have 15 pins, which is 7 devices, or 14 and a common earth. I think I can manage :-D

I am aiming to encase most of the dragon, (or at least large parts of it) in stainless steal. This is going to be more of an armadillo banded idea than a lizard scale style. Still working on concept ideas for that. The banded mail will be articulated in parts to allow for movement without generating gaps.

I have purchased a closed circuit security camera set with 4 cameras so I can see outside better, in all directions. They will feed to a screen inside. I’ll have to make the inside fairly black and light proof. I hope I can breath in it when piloting the beastie.

Red LED strip lighting has also been purchased to go under the scales in key areas, giving a red glow to the whole dragon.

The wings are going to stay fabric at this point. I don’t anticipate turning them into metal for a few years yet…

28 June 2014

Have begun rebuilding the neck. Vertebrae mild steal square pipe have been replaced with solid square bar mild steal.

 

Still to do:

* Linear actuators to control X and Y movement of the neck and head

* Connecting the actuators to a control computer and joystick

* Re-design the head to be bigger with more flame options

* Re-cover the dragon in metal

* Add LED lighting to spill out of the dragon, hook that into the control computer

* Add video camera and internal TV to allow the pilot to see all sides

20 March 2014

Finished? Well, for now.

 

 

My precious...

My precious…

Applying power to the beast – IT’S ALIVE! MWA HA HA HA HA!

Dragon

Dragon WAMA completed

Although it seemed it would never end.

All the troops were working on the dragon

All the troops were working on the dragon

17 Mar 2014

* neck wired up, just a bit more sewing any the horizontal axis control connected
* tail is completed
* body is almost completed – see neck above
* fire breathing – we have ignition
* eyes – we have vision
* legs are complete, just need to attach feet
* body close to complete, working on tail and neck attachment
* apply electricity and bring her to life

 

Minions working on covering the dragon

Minions working on covering the dragon

 

16 Mar 2014

Clare: first rule of dragons – it always takes twice as long

Joshua: Hopefully. . . That was the last weld and grind. . .

Joshua: I think the collective noun for helpers should be “a delight of minions”. Thoughts? Also, thanks Tess Healy, Helen Jekabsons and Sigmund Gotz.

15 March 2014

Covering the beast

Dragon - Covering

Covering the dragon

Covering the tail

Covering the tail

Dragon covering - Clare

Clare, working away at covering the tail

 

We had a dragonstrohic failure of the neck – boy that head and leverage are nasty combinations.

Dragon failure

Neck failure

Repairing the neck

Welding, grinding and repairing

Welding, grinding and repairing

Oh, and it breathes fire…

It breathes fire!

It breathes fire!

13 Mar 2014

Joshua: So the dragon is female (future offspring planned). She is of the bearded dragon variety. She is a silver and green dragon. Her breath is orange and yellow flame.

So far one of our team is keen for Esmerelda.

I’m keen for Verdis. Maybe “Argenta Verdis”, but then that is more of a description in pseudo Latin than it is a name. Line naming a dragon Draco.

Hmm, this is tricky.

We can always call her Bob.

9 Mar 2014

Making Legs

Shaping the legs

Shaping the legs

13 Mar 2014

* Skull shaping, welding and grinding is complete. Now to smooth it, paint it and put the insides in – fire and eyes.
* Legs x 3 complete – armature, shaping and fabric. One left to have fabric on it
* Torso is nearly complete – armature and shaping. Needs fabric.
* Wings – armature is complete. Needs shaping and fabric.
* Neck is nearly complete – armature and shaping. Needs fabric.
* Tail – we have the bits – needs armature assembly, shaping and fabric.

11 Mar 2014

Paint job – make the inside black

Black Beauty - post paint job

Black Beauty – post paint job

Welding and shaping the skull – not sure this is a dragon look…

Dragon? Or dog?

Dragon? Or dog?

Dragon, looking like a cat, with Jacques, one of the minions

Dragon, looking like a cat, with Jacques, one of the minions

18 Feb 2014

* Hip joints for front and back legs added’
* Legs are under construction
* Front wheel has been repaired
* Head is nearing completion

 

16 Feb 2014

Dragon update:

* Hip joints for front and back legs added’

* Legs are under construction

* Front wheel has been repaired

* Head is nearing completion

* We have wings!

Person holding wing armature

Clare demonstrating the wing armature

5 Feb 2014

Dragon update:
* Horizontal neck articulation auto return to centre via springs is set. Next step to add steering for it.
* more body armature
* creating eye socket assembly

30 Jan 2014

Dragon update:

* Head bracket attached to neck

* Vertical lift neck bracket attached to shoulders

* Step switch to engage electric motor installed and wired up – works like an accelerator peddle!

29 Jan 2014

Dragon update:
* More progress on the horizontal neck movement – should have it ready to test this weekend.

* Progress on the neck attachment mechanism, vertical lift progressing and hopefully way over engineered.

* Added a foot button to engage the engine – the “accelerator”.

* Improved battery connections.

* Removed lots of rust from the lawn mower frame.

Mower plus frame

Some basic frame and armature

27 Jan 2014

Progress update for the dragon.
* We have locomotion! Noisier than I had hoped though. Need to figure out what the noise is and fix it.

* Movement in the neck. One joint fine, 3 to go :-)

* Head base template is cut out. Now for the flame brackets, eye brackets and plate coverings.

25 Jan 2014

More progress on the dragon today. Basic neck vertebrae complete. Next steps:

* connect motor and test torque power vs speed

* add vertebrae horizontal movement system

* create mounting point for the neck to the body

* create shell for driver and dragon ribs

If all goes well, that’s Mondays jobs.

Lawn Mower

Lawn Mower donated by WAMA president Steven

19 Jan 2014

Good progress on the dragon for the Wama fayre. PS: it breaths fire.

fire-breath

18 Jan 2014

“Stand back! We are going to try logic!” with Clare vs the dragon

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