29 January 2018

Red Wedge Down

Whilst reviewing Red Wedge with a view to letting the Young Roboteers a go driving a small combat robot, I realised that one of the wheels was seized. After stripping the gearbox, I found that many of the gears had broken teeth which were jamming the gearbox.

So I need a replacement if Red wedge is to fight again. This is an old motor from an cheep drill I think it was B&Q we got them from. This was before the moder LiPo batter drills.

1 January 2018

K9 - Is there anybody home?

ROS on my pi
It was fun to build a K9, but there is something missing to my canine companion. That is intelligence!

With this in mind I'm investigating the Robot Operating System or ROS for short.

It has been painful getting it onto the Raspberry pi, as the instructions are not quite as complete as you would like and my knowledge of the raspberry pi is a little sketchy. Consequently it has taken about a week of the Christmas break to get it installed.

However, it is now on the pi (and backed up) and I've started on the actual ROS tutorials :)

So far I've got as far as driving around a simulated turtle, as above

2 November 2017

K9 Diaries - 2017 Mini Maker Faire Derby

K9 had another outing, this time at the Derby Mini Maker Faire, at the Silk Mill Museum on the 28th of October 2017 and look who he snapped on his K9 cam.

Dr Lucy Rogers

Improvements since Whooverville are the tail mechanism and the visor lights, although there were some malfunctions with the visor lights, as some of them wer not working, but this turned out to be just some poor connections.

I usesd an Arduino Mega 2560 for the visor control, mostly because of the large number of I/O's available, and there is a connection to one of the switches on the control panel to change from all on mode to a Knight Rider function.

Below is the mounting of the Arduino Mega 2560, mounted on a plate, which slides into features which are bonded to the inside of the head, then a retaining clip holds it in. I just need to figure out the cable routing.

Arduino Mega 2560 mounted

I've since fixed and added a random function

The tail now also wags at the push of a button on the control panel. This is controlled by an Arduino Nano, with a simple sequence to a servo.

We  ordered a Tom Baker cut-out to pose next to K9, who was well received with many people having their photos taken with K9 & Tom and lots of  children had fun pushing the buttons.

I'm still working on improvements such as fitting the laser extender mechanism and the Software for the visor lights, which needs changing to an inturrept rather than waiting for the loop to finish before recognising the input.

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.