A while back we discovered we had a problem with our roof leaking and this, in turn, made the roof space more welcoming to the Common Furniture Beetle, or rather it’s larval stage, known as woodworm.

We have had the roof repaired and it is leak free. Now we have to get the woodworm treated. In order for the contractor to spray the whole of the inside of the loft space to clear the infestation we have had to do quite a lot of preparatory work. This involved clearing the loft of all the stored equipment and materials and then lifting and stacking all of the wooden flooring we had put down to allow us access to that loft space.

You can see some pictures of the state of the loft before we started on our wiki page “What’s In The Loft?” page.

Here are some photos of what the Hackspace looks like now everything is out of the loft and what the loft looks like with everything removed and all the boards lifted.

It has taken a while but we now have a range of Hitchin Hackspace branded garments available to members.

The available options currently are:

• T- Shirts – 100% Cotton T-shirts with iron on vinyl logo. Logo can be on front back or both.
• Polo Shirts – 100% Cotton or Poly Cotton Polo Shirts with embroidered logo on front breast.
• Sweatshirts – 100% Cotton Sweatshirt with embroidered logo on front breast optional large vinyl logo on back.
• Hoodie – 100% Cotton Hoodie, Plain or Zip front with embroidered logo on front breast optional large vinyl logo on back.
• Lab Coat – White Cotton Laboratory Coat with Logo embroidered above left breast pocket.
• Soft Shell Jacket – Showerproof fleece lined jacket with Logo embroidered above left breast pocket.
• Your own garment not otherwise available, e.g. a long or short sleeved shirt or blouse, embroidered with the hackspace logo
• Option to have your name embroidered above or below the Hackspace Logo
• Baseball Cap, Bucket Hat or Beanie Hat Embroidered with the Hackspace logo

If you are interested in a garment and you are a member post a message in our Slack #merchendise channel.

We are also hoping to offer coffee mugs soon. Watch this space!

What they look like

Examples

T-Shirts

Polo Shirts

Sweatshirts

Hoodies

Labcoat

Soft Shell Jacket

Image coming soon

Your own garment

Baseball Cap and other hats

The Presentation

On Sunday Hitchin Hackspace hosted Leon Xavier from Anyvate who gave a presentation on 3D Scanning technology, processes and techniques. From DIY Xbox Kinetc scanning, through iPad LIDAR to his Creaform Metrascan Professional system.

iPad Scanning

Using a member’s 3D printed glazed clay pot as a target Leon demonstrated the iPad LIDAR scanner to generate a digital mesh of the pot. The results were really impressive.

Scanning a big screw

Next a 3D printed screw model was scanned to demonstrate how deep features needed to be handled and how software, like Meshlab, can be used to stitch together separate scans of the same object to create a complete model.

Scanning a Dalek

Leon finished the demo session by scanning Derek, the Dalek we are restoring, using his Creaform Metrascan system.
This showed the amazing level of detail, precision and accuracy it can capture across an array of challenging surfaces and textures.

The Creaform Metrascan is an incredible piece of kit. A tracking head locates the scanning head in space while you scan. It can be used to scan anything from the inside of a Transit van to something as small as a 30mm cube. Down to a resolution of 50um and accuracy of 40um.

A short 20second video shows Leon stood to the right of the Dalek “painting” the skirt and hemispheres of the Dalek with the handheld scanning unit. He slowly wafts the scanning head back and forth. The red crosshatch grid of the lasers can be seen moving across the surface of the Dalek. His movements are very similar to those of a spray painter painting a car body shell. Leon isn’t looking at where his hand is moving. He is looking at a monitor which is out of shot. The camera then pans left to a monitor on which you can see the scanned data appearing and the model building. It moves and rotates in relation to the movements of the scanning head and controls on it which Leon controls as he scans.

This session was the first of two sessions. The second is a few weeks later and will enable members to bring in objects they would like to get scanned, with the full capacity of the Creaform Metrascan scanner, for free. They will receive a mesh file for their item in return.

The monitor on a desk shows a view of the Dalek scan in progress. A section of the side of the Dalek skirt with hemispheres can be seen.

Anyvate offer professional high precision 3D scanning and workflows to individuals and Hackspaces at an affordable cost. If you are interested in Leon providing a demo session for your group or organisation give Anyvate a shout via their website www.anyvate.com.

Getting to look at the results

A week or so later Leon sent the in the scanned data of the whole Dalek. It is quite the data file, an STL of some 440MB. Here are some screen grabs of that data set:

General Views

Detail Views

Next zoomed in a bit closer. You may notice that the gun is missing the detail of the rods, collars and spacing hexagons you can see in the picture of Derek above. as these are all clear acrylic it makes it really hard for the laser reflections to be picked up. This is one of the shortcomings, although a minor one when you consider wat is going on with other very reflective surfaces like the gazing globes, the aluminium and the metal flake paint used on the body and hemis.

The Mid Section

In the next two pictures you can see that the mesh detail is picked up and details of the screw heads holding the slats in place. You can see some small round artefacts on the lower band. These are stickers applied to the lower band and are registration / datum position indicators (you can seem them in the video) that get scanned by the main tracking head. Once these are registered in the software it allows you to rotate the Dalek on its wheeled base to make it easier to scan all sides. The tracking head needs to be able to see the hand unit to successfully scan. This means you cannot scan the back of the Dalek if the hand unit disappears from view. The dots make it possible to move your target and pick up where the Dalek has been moved to.

The Neck and Dome

Some close ups of the neck and dome. As the neck rings aren’t fixed in place yet there is masking tape to show where they should go. You can see in the scans the masking tape and some detail of the neck bin mesh. You can also see on the bottom right edge of the dome that the scanner has picked up on the damage to the fibreglass of the dome. The striations across the dome on the left are artefacts of the scanned data where not enough data has been captured yet.

On the front facing view of the dome another patch of damaged fibreglass can be picked out just above the change in dome profile and to the right of the eyestalk.

Close up of Datums

Leon very generously scanned Derek and provided the STL file for free. The scan data isn’t as complete as it could be. We ran out of time! The data you see here is probably the result of a couple of hours of scanning and then several more to post process the data in to an STL file. Additionally the data is just a mesh. Not a solid model. As part of his business Leon can take the scanned mesh and turn it in to real CAD solid model data. However that can be many hours work and doesn’t come cheap.

One last point is that this is only the outside surfaces. With more time it is possible to scan the inside. It would be more complicated and you have to be able to get the hand unit inside.

The next step plan is to load in the CAD models from the measurements taken of Derek when we first started and see how far off the model is from actual Derek Dalek Data.

Hitchin Hackspace would like say a very big Thank you to Leon and Anyvate for taking time to come to the space and show us this amazing technology.

So, Pi Wars, where were we again?
After almost a year off from Pi Wars blogging (with Hitchin Hackspace distracted by the building refurbishment, now mostly complete, and myself also with heavyweight fighting robots), the Pi Wars activity is ramping up again here.
Hitchin has three applications going in this time, Myself & Rob with a full auto entry again, Martin (@PKM_ibles), the remaining member of the successful Tito team (now entering alone), and a new partnership of Neil and Alistair (aka Team Dangle (!?), @DangleTeam). I think Martin is intending to enter a smaller, cheaper bot than the usual Tito speed machine. Neil & Alistair are working on an interesting dicycle arrangement, with two large wheels and an underslung chassis. Dave, lead man on the Hitchin Hackspace team for many years, has stepped down to help with organising the event.

 

 

 

Now that the new theme and challenges have been announced, The Tauradigm team have been reviewing them against our previous build to see how much will need changing or additional attachments needing building. The challenges this year are:

• Lava Palaver
• Pi Noon – The Hindenburg Disaster
• The Zombie Apocalypse
• The Obstacle Course
• Eco-Disaster
• Escape Route
• Minesweeper

I will do separate blog posts on how we’re hoping to approach each challenge, but briefly:

Lava Palaver
The straightish line speed challenge from last year, near with a vertical speed bump too. We think the sensors fusion of IMU, distance sensors and vision will still work to give a fast time. We may need to detect for wheelslip or taking off in case that ruins the control algorithm

Pi Noon – The Hindenburg Disaster
Again, the same balloon popping event of the past few years. Without knowing what the potential spiky obstacle is, our sensor array should be sufficient to detect the walls and the opponent.

The Zombie Apocalypse
This new challenge is a modification on the popular duckshoot and space invaders challenges, where targets need to be hit with soft projectiles. Our autonomous aiming showed great potential two years ago, and the new flywheel launcher is looking good, so we’re hopeful on this one. We need to add a tilt mechanism as the targets are no longer at ground level. It’s not clear from the rules what the targets will be, or if they’ll be moving, both of which could give us additional software challenges.

The Obstacle Course
no new information on this challenge so its hard to tell what we’re in for. The ‘travellator’ obstacle last year would have been quite tricky to navigate autonomously with the approach we had planned. Now we know it may feature, we can probably incorporate a special case to deal with it.

Eco-Disaster
An interesting new challenge where coloured barrels need to be collected and moved to designated zones. We’ll need to build a new attachment to deal with lifting/moving the barrels, which might be quite complicated. This is also looking like a difficult challenge to code for, as there’s shape and colour detection required, coordinated moves and path planning needed. Should be interesting!

Escape Route
A variation on the minimal maze and canyons of mars, this is a maze like challenge with no prior knowledge and probably not continuous walls. We had planned to preprogram both the shape of the maze and the target course, then use the sensors and a localisation routine to figure out where we were in it and how to keep to that course. We’ll now have to use SLAM (simultaneous location and mapping) to both work out the maze shape and where we are in it, as well as have a path planning routine. in some ways this challenge is quite similar to the Eco-disaster, there could be a lot of shared code, certainly the learning on the tricky parts will help.

Minesweeper
Another new challenge, a little like a BATAK test used for human reaction times, where the robot has to drive to areas lit up. We could use the camera to detect the lit up panel and so be able to attempt this challenge with no new hardware, but we think it will be much more reliable and probably faster to use a dedicated light sensor attachment.

On the hardware side, we’ve been making good progress on the pcb soldering and are hopeful we can start a drive test and systems check in the next week.

Progress continues apace at our new building on Bancroft. Previously, we were painting, and had made door frames and bought kitchen bits and toilet bits.

Painting

Firstly, we finished the painting, which was preventing us doing a lot of other things. The office/kitchen/toilet walls and ceiling are now fully painted a fetching shade of “goodness, it’s bright in here”. This meant we could move on to several other things which were waiting for the painting to finish.

Lighting

As the Apollo 8 astronauts said just over 50 years ago, “Let there be light! And there was light.”

A lot of light. There are 14 LED panels, each putting out 3800 lumens. Or, to put it another way, if we used old-style bulbs, it would be over 3 kilowatts of power just in lighting. Since we’re using LEDs, the retina-scorching can be had for about half a kilowatt.

In case of power failure, there are also four emergency lights. Two in the office, one in the toilet and one to signpost the exit.

Power

With great power comes great responsibility, and we decided that part of that responsibility was to have a lot of sockets. There are 54 general purpose sockets, including ones for things like the kettle, and 6 which are on their own switch, dedicated to the laser cutter. The first person who daisy-chains a multiway extension lead will be made to stand barefoot on the plug until they’re sorry.

Windows

The windows were fitted a few months back. They’ve now been finished off with windowsills and sealed on the inside. One of the front windows is currently displaying a fetching “Hitchin Hackspace” LED sign.

Floor

Matters are afoot underfoot, with the original vintage tiles (or concrete, depending on which bit of the floor you’re standing on) having been covered by carpet tiles in the office. Meanwhile, in the kitchen and toilet, we have vinyl flooring, in case of spillage. In the kitchen, obviously. Eww.

Tea making

Things are progressing rapidly in the fluid-intake department, with kitchen units built and in place, water pipes and water heater fitted and the fusebox all neatly boxed in. The worktop and sink are in place, but not quite screwed down and connected up. After that comes the all-important kettle and fridge, and the vital business of producing tea can commence.

Toilet

Meanwhile, at the other end of the tea-drinking business, we have started the process of fitting a toilet. It being 20182019, it’s not sufficient to throw any old bog into the room, and rightly so; we’ve got a “Doc M” disabled toilet with suitable toilet, sink, anti-scald tap, grab rails, emergency alarm and so on. The toilet now sports a wheelchair-friendly wide door with the right sort of lock.

At the moment, we’ve got the rails, sink and alarm fitted. Toilet and pipework is next. And we need to put some privacy film over the toilet window, for obvious reasons.

Meanwhile, in the workshop

So far, we’ve concentrating on getting the office side up, as it gives us the ability to start using the building for things we already do. However, there’s a whole half (or seven sixteenths, to be needlessly more accurate) of the building to be built as a workshop. At the moment, it’s also acting as a handy dumping ground storage area while we work in the office side.

To help speed things along a bit, we used some of the grant money we’ve received previously to engage a local builder to carry out some work in the space. He fitted the windowsills and toilet door, as well as doing some much-needed repair on the roof structure caused by some damaged tiles. In the workshop side, he built up the dirty workshop wall to ceiling height (as with the toilet on the office side, this was originally a disabled cubicle), and fitted a door to it. There are also doors between the office and workshop to keep noise, dust and so on where it’s supposed to be.

What’s next…?

We’ll very soon be at the point where we can start using the building, so it’s likely that we will. There is still much to do, though, including fitting the air conditioning to keep the place nice and warm/cool as appropriate, and adding ventilation for the laser cutter, while the workshop side needs a good clear out, a lick of paint, a new ceiling, some lighting, power, etc.

We’ve also just a very exciting offer of some furniture to fill the place, so in about a month’s time, the place should really look the part.

Next month will hopefully see us using the new building full-time. In the meantime, if you’d like to know more, pop down to Ransom’s Rec on a Monday evening and say hello.

 

The new maze course has been revealed for Pi Wars:

The actual course being revealed is a little of a surprise, as the challenge description initially said the design would be a surprise, encouraging either a generic approach (like wall following) or a ‘maze solving’ strategy. Now the actual course is known, a more specific and optimised solution will probably be faster and more reliable.

Last year we looked at different approaches to the course, to see which might give the fastest or safest route. This year we’re expecting to have a better handle on where we are on the course (using the encoders and IMU, as well as distance sensors), so that may open up some faster and more sophisticated lines. We thought it was worthwhile to sketch the options out and see how the theoretical times compare, to see how worthwhile it might be to do the development.

First up we have the simplest planned route, one that’s relatively easy to program using only information from two or three distance sensors and is fairly safe: the straight, centre line course, turning on the spot in the corners:

This is the strategy we started with last year (see test video here: https://youtu.be/EV7YIHr5feg?t=518) Like in previous years, we’ve also developed a simple model of how fast we expect our robot to accelerate:

 

 

 

Previously this approach has been fairly accurate at predicting times in the straightline speed challenge, so we’re fairly confident in using it to estimate performance for the maze.

Using this model, we can combine the acceleration profile and the distance of each straight line segment of the approach above and estimate the transit times. Adding on a time to turn 90 degrees at each corner (we’re assuming 0.1 seconds, as that’s about what Piradigm needed to turn 90) gives a predicted total time of 5.3 seconds to complete the maze. If you’d attended previous Pi wars, you may think this was a ridiculous prediction, as most competitors took  20-30 seconds. This was mainly because they take a very tentative approach to the maze. Last year in practice Piradigm could fairly repeatably achieve 10second times whilst not running “full throttle”: (https://youtu.be/EV7YIHr5feg?t=541) and we did achieve one ~6 second time, so its certainly possible.

Can we do any better than the straight line route though? As you may have seen in the video linked above, a slight variation is to do smooth turns for the corners instead of stopping and turning on the spot:

 

Last year we found this to be much faster and no more risky. Predicted time: 4.3 seconds, a handy saving. This is assuming each corner is taken at 1.6m/s, which is at approximately the limit of traction of the tyres. Hopefully the IMU will allow us to stably and repeatably skid a little in the corners, otherwise we’d have to go a little slower to retain control.

So that’s good, but can we do any better? It still doesn’t look much like a ‘racing line’ as you’d see in motor sport. If we know where we are on the course at all times, can we corner faster? or tighter?  We can approximate something like a racing line by increasing the turn radius (but keeping it a constant radius) and clipping the apexes on key corners:

(note this isn’t a true racing line, usually drivers won’t drive at a constant radius through all corners, it will be a different parabola-like shape with a late apex, starting accelerating before finishing the corner.)

With the larger radius turns, we think they could be taken at more like 2.3m/s, and the distance travelled is a fair bit shorter than the second course, so the predicted time plummets to 3.2 seconds!

That is a nice target number but in reality we wouldn’t plan a route taking us so close to the sides, we’re unlikely to be perfectly positioned and hitting a wall can disorientate the robot and end the run. How much longer would it take if we take a racing line with a safety margin? say 75mm clearance?

The ‘safer’ racing line is ~0.3m longer and the slightly tighter corners mean going a little slower at 2m/s, but the predicted time is still only 3.6 seconds.

That’s all great, but the above predictions were assuming no downforce. As we discussed in our week 3 update, we’re intending to fit a vortex downforce generator. So how much faster can we go with that?

For the ‘safer’ racing line we’re predicting a 3.1 second time, and the faster, riskier line a bonkers 2.6 seconds.

 

Some crazy numbers, lets hope the software and electronics can give us the control needed to get the hardware to deliver the times its capable of.

Not much progress to show again this week. We’ve again been researching and trying to get our heads around Kalman filters, and have been learning a new software package to design our chassis/pcb.

In every one of our previous Pi Wars entries, we’ve had issues with loose wires causing erratic behaviour at some point. We’ve often wondered if having a pcb made to eliminate  much of the wiring would be easier and more reliable. So this year we’re going to try to have as few cables and connectors as possible and mount most components directly to a pcb.

We’ve designed a few small pcbs in the past, but we’ve never been happy with the pcb design software. This week we’ve been learning Diptrace, and now have the beginnings of a schematic to show for it:

We still need to add some components, like the drive motor controllers and connectors for components that won’t be mounted directly to the pcb (like the IMU, batteries, motors etc), then we can move onto routing the actual pcb design

In other news, the cheap encoders have arrived, but we’ve not had chance to test them yet.

 

 

 

 

 

Pi Wars has many challenges where fast acceleration and cornering are important for the fastest times. Certainly last year Piradigm, whilst it wasn’t the most powerful robot, when running well it was still traction limited in the Minimal Maze and Over The Rainbow Challenges. This year the Straight-ish Line speed test may also require good cornering and the Pi Noon challenge always favours good drivers (or code!) even more if the chassis has good handling. We’re hopeful that our software and hardware this year will be capable enough that extra traction would increase performance. To that end, we’ve started testing a novel ‘vortex generator’ style of generating downforce:

Before we explain the weird design,  some background:

Formula one cars corner much faster than normal cars due to their aerodynamics: as they move along,  they use wings to deflect the air upwards, pushing them into the ground, increasing grip without increasing weight. This works great if you have the power and speed to do that. unfortunately most Pi Wars challenges are completed at less than 5mph, so the wings would need to be huge to have any effect.

In another, more closely related analogy, Micromouse robots need to accelerate and corner quickly to solve their mazes in the fastest time. As designs have developed, the winning teams in this competition now all use fans to generate downforce. The mice have a flexible skirt under their chassis, much like hovercraft have, but these are arranged so the fan sucks the air out, creating a low pressure even when the mouse isn’t moving, sucking the robots to the ground. This works well since their course is very flat and smooth, so the skirt has almost no leaks. Check out their incredible performance in this video from a competition this year:

Inspired by those, and the small toys that can run on ceilings, I first included a downforce generator in one of my projects in my entry for power tool drag racing:

This design was a little different to the above mechanisms, it used a vortex suction generator, which is a vaned, high speed spinning bowl that spins the air rather than sucking it, to generate the required low pressure with lower power consumption and less reliance on a good seal with the ground. The theory is that because the air is spinning, there must be a pressure gradient to keep the air going in a circle. Since the outside of the bowl is at atmospheric pressure, the centre must be at a much lower pressure, sucking the bowl down.

For Pi Wars we’re hoping to use a similar design but on a smaller scale, and only if the rest of the system is fast enough to benefit from it. So far we have 3d printed the above CAD:

And done some spin up tests in a test rig:

In this test, we held the rotor above a metal toolbox, that was supported by some scales. We were hoping to both test if the rotor could survive the very high speeds required and,  if it did, what level of downforce we could generate (measured by the lift or reduction in weight of the toolbox). For the test we were stood well back, with a full face shield on in case the worst happened.

From the test video, you can see it was a successful test: the rotor survived spinning up to ~14000rpm and generated over 900grams of downforce, despite having over 5mm of ground clearance! For comparison, from the latest CAD model we have of the overall robot design, we’re expecting the all up weight to be about 800grams. Which means we should be able to corner at up to 2g, if we have sufficient control.

 

On the software side, we’ve been further researching kalman filters and how we might be able to fuse encoder data with the data from the IMU to give us the best possible positional information, and we’ve also had a few more components arrive:

 

Hello again. Long time no update.

In some senses, there hasn’t been much to report. For the last few months, the inside of the building didn’t look much different to how it looked before. We’ve been plasterboarding and jointing and building partition walls, but it’s been a lot of incremental improvements, which paled in comparison to the last update where we literally changed the way the whole building looks.

But then we painted the place, and it looks glorious! We’re currently between coats, so the first coat is mostly up, and it looks brilliant. But it needs a second coat before we move on to fitting out.

The toilet is now properly enclosed, with a doorframe into the loo room, and a wall above it. There is wiring in place for the disabled emergency alarm. After it’s painted, we’ll be putting down some floor and fitting it out.

The gap between the office side and workshop side has been shrunk down to double-door size by the addition of a central doorway between the two halves of the building, which has a doorframe and wall above it.

We’ve been on a bit of a shopping spree, and once the painting is done, we have a load of stuff to fit, including a full complement of lighting, the tea-making area (cupboards, worktop, sink, etc), electrics (sockets, trunking), the toilet (sink, toilet, door, accessible handrails…), and air conditioning to keep the place warm in winter and cold in summer.

In other news, we have an official address which can recieve post. We had the address assigned some time ago, but we couldn’t make it “live” without a working letterbox and a number on the building. We now have both of those things. Feel free to pop a few quid in an envelope and send it to us; we can make good use of it.

In the meantime, as soon as the paint is dry there are a dozen things we can be getting on with all at once, so expect further updates soon. And if you’d like to help out, pop down to Ransoms Rec Pavillion on a Monday evening and say hello.