2 October 2017

K9 Diaries - Development

ADC and level shifter
The first job is battery monitoring, as I don't know how long to expect the batteries to last then it is important to have some feedback from them to determine their charge level. The Batteries at 12.4V each and the minimum discharge level is 9V.
A simple voltage dividing pair of resistors and a connection to the Raspberry Pi via the I2C bus has been made. The Adafruit library and example program has been added to the Pi and tested, so I just have to wire the inputs to the batteries and adjust the program to monitior the voltage and calibrate the output to reflect the true voltage.

7 September 2017

K9 Diaries - Motor Controller Issues.

K9 wiring
The inside on K9 are pretty straight forward. There is a Sabertooth motor controller. Its a 2x32 generation 3 controller, which means it has a USB interface to an application called DEscribe. With this you can monitor the inputs and outputs, which is handy. You can also specify the battery chemistry and many other bits and pieces.

I've just fixed the motor controller location between the drive wheels, so it is no longer on top of the batteries.

The other upgrade is fitting the Arduino Nano to control the tail servo. Again a little more thought  when I was designing the wag mechanism, so there was somewhere to mount it, but ti-wraps to the rescue, and a mount from the walker robot and it is secure. The next iteration will have a dedicate mount point. The point is the tail which now wags!

I decided to fit the 4 switch elements in the control panel, and wire them, and the I2C pins of the control panel Nano to the D-type connector which I've used as an interconnect. The I2C pins are fur future use / development. One of the switches can now be used to activate the wagging.

The switches are a low level implementation but a first step in getting things going.

3 September 2017

K9 Diaries - Whooverville 9 2017

Success, K9 was completed for Whooverville 9 at Derby Quad, his first ever outing, all the hard work was well worth it seeing the smiles on the faces of people that met him. I lost count of the number of people that complimented me on the build and a few even asked to buy him, more than my life is worth to sell him though, Debs finally has a dog and she's not parting with him lol!

I had to have a go in the TARDIS :)  K9's control panel looped through a sequence of K9 and then 200 random selections of the lights.

The screen was fully operational, although we didn't want to infringe any copyrights by playing Dr who episodes at a public event, but as well as photo capabilities, K9 has movie playing abilities on his screen via his built Raspberry Pi.

His antenna ears operated continuously for the whole event, as did his control panel, and we had his camera taking photos every 10 seconds to record what he could see during the day.

Although we did have to cut out a fair number of shots of peoples trousers. Next time we'll have a perimeter around so we get see more people and less of their bags and behinds, we'll also encourage the people to smile for K9's Timey Wimey Cam as Debs has christened it. Below is a video Debs made from the images that K9 took.

Sadly his drive broke down, some issue with the motor control / receiver which needs to be investigated but all in all it was a brilliant experience,really good to see the smiles on the faces of people young and old who wanted to meet K9 and have their photo taken with him. We're already looking forward to Whooverville 10, see you there!

28 August 2017

K9 Diaries - 4 days to go

Dog tag
Its come down to the last 4 days now, and I've persuaded Debs to make me a collar, and I 3D printed a dog tag.

The construction was easy enough, she covered a strip of leather with some tartan fabric and added some Velcro to the edges to fasten it. 

The D ring that the tag hangs from was taken off a collar that once belonged to her dog Mitzie, who died 17 years ago now, Debs kept her collar and thought it fitting to use a part of her beloved dogs collar on my beloved doggie project.

The 3D printing in the tag didn't stand out as much as I would have liked, so Debs applied a couple of layers of 'Empire Gold' Pebeo Gilding Wax to the raised areas, she likes it when she gets to use her hobby on our robotic projects.

head, primer and more filling
Unfortunately with just 4 days to go to the event, K9's head isn't ready yet and I've not figured out how to attach it to the body and its becoming obvious  that more filling is required.

After drilling the holes for K9's ears, and the visor cut-out, I primered the top of the head.

Debs seems to be getting worried, and keeps asking me if it will be ready in time! Whats that all about?

After a bit of sanding it'll be on to the top coat.

So I nearly have a head, but it is time to be thinking of having a couple of days off work to give K9 a better chance of being ready :)


top primer

Now the control panel is painted, I can move on to assembling the components. The bezels I've printed fitted into the 2 large holes and the 12 indicator lamps took no time at all to fit. If there is time, I'll fit 4 momentary switch contacts to the top 4 switches, and use these as manual operators of the ears etc

Wiring the control panel is time consuming, and the software for the Arduino isn't started, let alone complete.
Fortunately it's not a difficult job as there are plenty of resources out there for Arduino, and the experience with programming the Chompalots eyes and walker robots servo sequencing has put me in good stead.

26 August 2017

K9 diaries - 7 days

Top of the head
7 days to go, and I've still not finished anything! I've still got a pile of unfinished dislocated bits. The head has at last been made and tidied up. I was scouting round trying to find something to use as a mould for the nose, but nothing was forthcoming so I modelled one on the CAD system and printed it on the 3D printer, then just stuck on with a bit of double sided tape to the head pattern before making the mould.

control panel mould

The control panel mould is a bit rough and ready but seems to have come out all right. I used copious amounts of wax mould release.

Below is the control panel and top of the head being produced in their moulds

The control panel is out of  its mould, and the Easylease release agent performed reasonably well,

Another package arrived today, hopefully the panel switch/lamps. The battery charger arrived yesterday,  so it is all coming together maybe.

Control panel, pre-tidy
I couldn't resist perching it on top of the body shell after I'd tidied it up a bit (below).

Now the control panel has appeared, the hole in the body shell can be made to suit it. Then the accommodation bits to stop it falling straight through need to be added. Then it is on to the body being  primed and painted, after a bit of sanding. This would be a massive step, when K9 starts  to come into view.

trial perch

Once the body is painted all the systems can be fitted and integrated. The sub assemblies collected together and we will see what problems and missing bits we still have to sort out.

The side panel is going to be a major part which needs making. There is no primer remaining and I think I need some more MDF!

My attempts at tagging K9, with primer at this stage

22 August 2017

K9 Diaries - 11 days to go

Head Mould

Only 11 days remaining before the appearance of k9 the wonder dog, so I'd better get my skates on. Fortunately I've been working slowly but steadily towards the ultimate goal. Sometimes it seems like he'll never be done, and so many different things to organise, and co-ordinate, with things slowly lumbering into position, it's like the aligning of the planets.

Fortunately the head mould did come apart mostly OK. Just a little sticking on the front of the head in the mouth area. Relatively cleanly, so only a little tidying up and it and it should be good to go.

The control panel is also progressing, this needs to be completed so I can gauge to correct size for the hole to accommodate in the body. Then I can move on to prepping and painting, before fitting all the systems in the body shell.
I decided on a two part mould. Hopefully the two parts will pull apart easily. Again with the experimental, I went for plain MDF with no primer, just 6 or so layers of wax release agent, all holes and imperfections filled with wax.

Both sides of the control panel mould are now covered.

16 August 2017

K9 Diaries - A Body in the Garage

Removing the mould
It began like any other evening, visiting family, what I really wanted to do was to get home to deal with the body in the garage. I had quietly secured it the previous evening, and I just needed time for the idea to gel. When I finally got into the garage, it was like driving a wedge between reality and a shadow. How would it turn out, would this be the end of a dream? Would the Fibreglass police turn up at my door and charge me with insufficient application of release agent?

One side revealed
After the wedges had been gingerly tapped in, the mould began to release again quite easily at the top, but it seemed to be sticking in the recesses again. Oh the torment, until with a cracking sound it just popped off. I was so relieved!

It also looked quite good for saying I'd taken a chisel to the mould.

Then it was on to the other side, I wasn't out of the woods yet.

Right side and front.

I was on a roll, the wax release agent is definitely is the way to go. Perhaps I'll try Easy Lease again in the future but I'll test it out on some not so important bits before I roll that dice again.

Here are three sides revealed, it was going too well!

Time for the bum

The rear section was a little  tricky, I thought it was going to give me some problems, but in the end just a little gentle teasing and plastic wedges tapped in all round, was all that was required.

The top section was a breeze. So this is it, K9 has a body shell, just a bit of a trim to remove the excess fibres around the edges and a little light sanding required around the edges.

K9's body revealed
Photos by my lovely wife, Debs :)