In August, a sixteen year old student reverse-engineered iMessage, and published an open-source Python library allowing anyone to send and receive encypted messages with Apple users right from the command line. Crucially, he didn’t “break” the encryption; he simply figured out how to use it, meaning that while Apple has been forcing its users to communicate with all non-iPhone users via insecure, unencrypted SMS messages if they want to use their default messaging app– which they’re also not allowed to change for a different default– JJtech had figured out how to allow the rest of the world to meet iPhone users in their own walled garden when they refuse to or can’t leave it. In a climate where the tech robber-barons are finally undergoing some antitrust scrutiny, interoperability of messaging platforms is an obvious issue to address; and indeed, after years of pressure and openly admitting that lack of interoperability was the goal in order to force people to buy iPhones, Apple has finally said it will adopt RCS in 2024, a secure standard that will replace SMS and, hopefully, if Apple doesn’t break it for their own users on purpose, fix the problems with group messaging that currently exist on the iPhone-Android divide.
Reverse-engineering for the purpose of interoperability is explicitly protected by the Digital Millenium Copyright Act; so a company called Beeper hired JJtech and rewrote his code to create the beginnings of a universal texting app, which would start just as a way for Android users to send iMessages but planned to incorporate RCS, Discord, Whatsapp, and Matrix chats all into one space. Apple moved to shut it down, Beeper got itself back up, and the two are currently in a (probably protracted) cat-and-mouse game of adverserial interoperability.
That’s not actually my point. My point is that I got curious about Eric Migicovsky, Beeper’s CEO; who, it turned out, had also created the first functional and widely available smartwatch.
But not just any smartwatch. The Pebble was the first Kickstarter campaign to raise over $10 million dollars, and created the demand for smartwatches that Apple would later exploit. And, indeed, Apple eventually ran over Pebble like a, well, Mac truck. But Pebble, amazingly, survived, and in a way that Apple devices could never. From ifixit’s Rebble with a Cause: How Pebble Watches Were Granted an Amazing Afterlife:
The next wave of Pebbles focused on fitness, something Apple was already pivoting toward with its second Watch, but Pebble didn’t have Apple’s money. After months of last-ditch fundraising attempts, Fitbit paid a scant $23 million for Pebble’s software assets and engineer hiring rights in December 2016. While Fitbit would not officially support Pebble’s customers, Migicovsky worked out a deal that would refund Kickstarter pre-orders, and, he hoped, keep the more than two million Pebbles sold, and their apps, working for as long as possible.
In hindsight, he nailed it. Pebble has been the most successful hardware company failure in history. Compare this to Revolv, whose acquisition by Nest led to an abrupt shutoff of smart homes around the world, or personal cloud device Lima, or, really, any Android device more than a couple years old.
From the rubble formed Rebble, a team of motivated fans, developers, and ex-employees, rushing to reproduce years of development in a matter of days. Frantic to document critical APIs and development tools before the servers shut off, they grabbed everything they could. The first replacement app store appeared quickly, aptly code-named Panic App Store. Within a few days, they had firmware, core and third-party apps, all the dev tools, and more. And they preserved it all on a wiki, right down to the pinouts.
More than 177,000 people have connected their devices to Rebble’s services. Not everything can be free, because the APIs for voice dictation and weather are not cheap—$750,000 per year, if 100,000 people used them, Berry said. And yet, nearly 9,000 people pay yearly subscriptions. Full disclosure, in case you haven’t guessed: I pay for Rebble’s services on my Time Steel, which I wore in our video about … the Apple Watch.
The Rabble project not only has replacement web services, it also has a network of resources for replacing the batteries in Pebbles, 3D printing replacement buttons and cases for them, and is even working on creating entirely new hardware for RebbleOS to eventually run on.
So, I went on Facebook Marketplace and searched them up– and sure enough, there was one for sale close by for a whopping $10. Admittedly, the price point was probably partly because it was one of the very first generation of the watches, probably manufactured around 2013. While later versions were somewhat more refined aesthetically, the original looks like exactly the smartwatch that time travellers from 1960 would expect to find people wearing in 2013:
Anyway, I charged up my new Pebble and followed the instructions on the Rebble setup guide, and within a few minutes had a fully functional smartwatch, with an all-freeware watchface and app store, at my disposal. I joined the very active Rebble discord, where development of both hardware and software is still ongoing, and where they recently hosted their first hackathon for apps and watchfaces, but turned out not to need to ask any questions at all about the process– it just worked.
It’s hard to remember, sometimes, that “being on the computer” used to be fun. Owning and using tech has turned from something that feels like a frontier of discovery and possibility into a kind of grim obligation; the vast majority of devices and internet services are predatory and bad, but you need to use them anyway, and they’re designed to try to make you keep using them even when you actively want to stop, and they’re spreading misinformation and misunderstanding, but what are you going to do about it?
Pebble is fun. Pebble is a good device in the way basically nothing manufactured since is. Although it can put through any level of notification from your phone that you want, and you can install plenty of apps giving you different ways of interacting with those notifications, some of the best apps available for it are things that have nothing to do with your phone at all.
One of my favourites, for instance, is called “wristronome”. It is the best metronome app I have ever encountered. It uses the three buttons on the side of the watch as up/down tempo and start/stop, then uses the very strong vibrations of the Pebble as a metronome. Although there are all sorts of android and iOS metronome apps, almost all of them come with ads, and have weird unusable interfaces that take way too much time just to turn your metronome up a few clicks; so I have been using the same Korg TM-40 since, well, before my Pebble was born. This is the first app that provides a genuine challenger to it. Not only does it do everything it needs to do as a metronome, the vibrations make it appropriate to use in crowded warmup rooms at gigs or auditions; whereas having a loudly ticking metronome on your stand in a room where everyone else is trying to practice and warm up too is kind of rude, this is unnoticeable to everyone but the wearer.
Another of my favourite apps is called Tilt Calculator. Unlike Wristronome, this is, admittedly, not a better calculator than any calculator I’ve tried before. In terms of its ease of use, it’s, well, kind of insane. But that is the point: Tilt Calculator is a completely insane piece of software, something that has never existed before or since, something that could only exist in this particular ecosystem. To operate Tilt Calculator, you tilt the pebble until the cursor rolls over the number you want like a ball bearing in one of those little maze games, and then press the side button to select it.
Indeed, this is not a convenient way of doing arithmetic. But it is an entirely new way of physically manipulating numbers, unheard of until now all the way back to the invention of drawing in the dirt with a stick. Apple would simply never think up something this fun.
There are plenty of other genuinely useful apps– tiny maps for your wrist, health tracking, apps to set a location that it will then lead you back to, etc– as well as plenty of gloriously useless ones. One of the best features of the Pebble, though is probably its battery life; because it has a transflective liquid-crystal display that requires no backlighting in bright environments and draws almost no power to continue showing an image, a new Pebble battery lasts for about 7 days, and even my ten-year-old battery lasts for four days. Compare that to the Apple watch, for which the company claims a new device’s battery will last 36 hours or up to 3 days if you use “low power mode.”
The only downside to my Pebble is that it’s, well, kind of ugly. But then, there are quite a few nicer-looking ones– and now that I’ve discovered the secret of the Only Good Smartwatch, I’ll probably pick one up when it comes up on marketplace of kijiji near me.
Learning phasor analysis; contemplating that it’s almost too metaphorically on-the-nose that analysis of purely real functions can become vastly easier when they are given an imaginary component. A similar feeling to that evoked by the process for solving the Gaussian integral, in which turning a one-dimensional problem into a two-dimensional problem provides an almost offensively simple answer to a seemingly intractable problem.
Linhan Cui is the real deal, as a conductor, and will soon be snapped up by a major orchestra if there’s any justice in the world; in the meantime, I treasure every concert I get to play under her direction.
What if Clive Barker had a fever dream of Snow White as imagined by Angela Carter? This is the question nobody but me asked, but I imagine Angelin Preljocaj’s Blanche Neige to answer.
Winnipeg is one of my favourite orchestras to play with, and recently I was invited to play guest principal for the Royal Winnipeg Ballet’s production of this show. The draw for musicians is that it’s a new ballet constructed entirely out of Mahler symphonies; but once I watched a video of a previous production sent to the orchestra, I was also excited for the reaction to the work, which is– look, I don’t think it’s particularly controversial to say that this is a very sexy ballet. The costumes were designed by Jean Paul Gaultier. The sexy cats had headgear intended to convey the danceable impression of ball gags. When Snow White eats the apple, it’s less a trick and more of an orgasmic force feeding.
I’m not casting aspersions. It all– in my opinion, from the production I did watch and the reaction of the Winnipeg audience– worked great. There is something about the project of presenting Mahler as anything other than an integral whole symphony that invites, nearly demands, a certain amount of enjoyable grotesquerie; Ken Russell comes to mind. That said, the music was not as chopped up as you might think it would have to be; no crazy cuts and very few significant alterations to make the music fit the dance. There were even two entire movements, the Purgatorio of the Tenth symphony and the third movement of the First, which accompanied probably one of the most memorable stagings in the show: the introduction of the seven dwarves (I think credited here instead as “miners”), an entire vertical ballet taking place on a sheer rock face, one of the pieces of it that is available online:
The only really wacky alteration was this section, from the very end of the 3rd movement of the Third symphony, being repeated eleven times:
…which is how I learned that in the Brothers Grimm version of the story, the happily ever after is that the Prince orders the evil Queen to dance herself to death while wearing a pair of red-hot iron shoes, which is what is happening during the above. Disney sure didn’t mention that part!
Anyway, I’m very much hoping that the National Ballet or some other company around these parts picks this up, as I’d like to see it properly!
The last time I was at the National Music Camp, I was 14 and played a bassoon for the first time in the beginning bassoon elective. This summer I returned as a faculty member. (Full disclosure… once I started playing bassoon in earnest, my allegiance was firmly to the other music camp, on the grounds that the dining hall was quieter and they didn’t make you do “evening program,” so I never actually attended as a camper on bassoon.)
I didn’t take all that many pictures– one of the excellent things this camp did was take away all the camper’s phones, so there just wasn’t much photo-taking culture in the absence of ubiquitous devices. To be honest, I suspect a lot of the kids (those who didn’t sneak them in anyway, that is) were relieved to have them gone for a week. Hey, maybe they’ll do the same for the faculty in the future!
Laurel leading a very cozy band sectional
A bat taking a rest outside the bassoon studio (I realize this does not exactly look like the peak of bat health, but at least it flew away and we didn’t have a dead bat to deal with…)
Not a camper any more… they can’t force me to stay in the loud horrible dining hall… ate all my meals on the dock with my buddy Montaigne.
Very good doggo getting ready to listen to faculty wind quintet rehearsal
Pulled out the 2nd cello suite for a faculty concert
Arcady Ensemble’s “Garden Walk” concert– the first half was a setup where, instead of musicians assembling in a central location for a concert, musicians are spread out through the Whistling Gardens playing solo works with related thematic material, and the audience walks around through them. Ronald Beckett’s music is always fantastic and the dedication of his audience to the ensemble is impressive.
Project 4 introduced the premise of having “clients” for whom we were tasked with making a product– more or less any product. This seemed to cause wide-scale confusion, since it was not immediately clear what kind of expectation of completeness came along with the introduction of real live human beings who were giving their time and energy to describe their daily lives and health issues to the first-year engineering class. In Project 3, we knew what “success” looked like: if the mechanism dumped the recycling into the bin, we’ve succeeded. The definition of “success” here was somewhat obscure. Was the bare minimum accomplishment supposed to be creating an object ready to be physically given to the clients at the end of the two-month period of the project, with the expectation that they would be able to use it regularly and find it helpful? How useful is the object supposed to be to “count,” especially when compared against the assumed null hypothesis of having one fewer gadgets to keep track of?
Also: what, exactly, would a useful object do? “Problem framing” was supposed to be the focus of the first few weeks of this project, during which the clients, Tim and Kim, came on Zoom to the class lectures; but they didn’t (perhaps had been instructed not to?) actually make any “asks.” Labs for the first few weeks of this process involved mostly group discussions. Unfortunately, the techniques of planning and decision-making that the class was intended to teach, which were required for lab submissions, seemed to actively hinder the process when the goal was so nebulous to begin with. Much has been made during this course of the importance of a “problem statement” that is “solution neutral”; i.e., you want to express the reason for solving a particular problem and the metrics that will tell you whether or not you’ve done so, without committing to, making reference to, or ruling out specific design elements. This makes excellent sense for most professional situations, where a client will come to an engineering firm with a specific thing they need done, made, or improved upon. Solution-neutral problem framing means keeping the big picture in mind and ensuring that the client’s needs aren’t overshadowed by the design process itself.
In this case, however, there seemed to be a lot of confusion about how to generate a “solution-neutral” problem statement without a particularly well-defined problem. Kim and Tim are a couple who both have complex health issues and disabilities. Tim is almost completely blind, and Kim is a power-chair user; there is a large set of problems associated with disability that are simply not solvable, especially not within two months with limited resources of fabrication and, frankly, skill. Many groups seemed to be struggling with the insistence that we state a problem that we were going to solve, without hinting that we had any ideas at all about how to solve it. True solution-neutral problem framing, in this case, would mean committing to solving a problem that you may quickly realize isn’t going to be successfully solved. And there is, of course, an inverse relationship between the significance of a problem and the ease with which it can be solved; the problems of lack of sight, lack of mobility and pain are both the most significant and the ones not likely to be solved in the scope of this project. What’s left, then, is mostly “gadgets” which may or may not end up solving small annoyances.
My group had, then, several different concepts for gadgets to choose between, many of which seemed common to many different groups. Tim talked about the challenges of cooking now that he has entirely lost his sight, and kitchen gadgets are a category where it seemed possible to come up with a well-defined problem to solve within the time available, so a quick glance around the 1P13 classroom revealed a veritable warehouse of souped-up utensils. Our three main contenders were an Arduino-controlled device which read out the level of water being poured into a vessel (a device that already exists in a smaller form factor than we would be able to build, and ended up being created by at least one other group for the project), a cutting board with a bunch of Handy™ attachments, which is what we and several other groups ended up doing, and an auto-cutting fork, which I was a little fond of on the grounds that it was at least unique, if somewhat impractical:
…yeah, it may not look like much, but… OK, there’s no but to that sentence. If we had the ability to fabricate metal, it could have worked– the idea, not exactly clear from a very quick CAD example, would be to have a fork that used a little spring to move a circular wraparound knife up and down; so you can stick the fork into the food, push the knife down to cut a piece of food around the tines, retract the knife (have it held up there or covered somehow so it’s not pointing at your face?), then use it as a fork. As it is, fork tines aren’t a good candidate for 3D printing because they need to get very thin, laser cutting can only cut flat parts along a single plane, and we would have no way of fabricating a circular knife. So, cutting board it was. A groupmate made a cardboard version of the concept, which a) holds the tip of the knife in place, b) has a slide to push food off the board, and c) has a container on the side for the food to be pushed into.
After this, we spent quite a while trying to figure out how to fabricate a better version with the resources available. The two methods of fabrication available through the class are 3D printing and laser cutting of acrylic. Most of the components we needed were long and flat; theoretically candidates for laser cutting, except that they were longer than the sheet of acrylic that each group was supposedly limited to. (Later we learned that the stated limits were more guidelines than actual rules, but that wasn’t officially circulated information.) Of course there are ways to buy all sorts of these materials, such as a knife– but aren’t we supposed to be, you know, making a thing ourselves? What level of “fabrication” was even expected of us? There was supposed to be a $100 limit on materials, but of course rumours swirled– “I heard that group spent $300 on electronic components and clamed they’d had it all lying around the house,” etc– and direct questions about the expected balance between a professional-looking product and a product we actually fabricated ourselves were met with apparent alarm and confusion.
This theoretical speculation was cut short when, one class, a TA informed us that, despite the worksheet’s asking for a “screenshot” of your current prototype, we were actually required to have a new physical prototype built by the next day. So we stopped arguing about how to cut down the 3D printing time on the elaborate knife holder we’d planned. Instead I stopped by Dollarama on my way home from school, bought out their actually pretty extensive craft section, and made this:
If it’s not clear– there are straight razor blades sticking out of that cleaver-looking thing. My groupmates found this very funny when I brought it to class the next session.
I had assumed that this was just a thing I was building so we’d have something to take a picture of for the submission due the next day; but once it was there, the constraints on fabrication remained, and it wasn’t obvious that we would really be improving it much by replacing wood parts with other materials. Wood is, after all, a perfectly acceptable material for a cutting board as well as many other useful objects, even if “pre-fabricated wood in sizes determined by Dollarama and glued together” isn’t exactly the ideal for high-quality woodworking projects. (I learned during this project that there are woodworking tools available at the Hatch centre; too late to be much use here, since it takes time to get certified to use them, but now that I know that I have all sorts of projects I want to bring there…)
More confusion along the lines of is this, fundamentally, what we are supposed to be doing here? A TA told us the thing basically looked fine as an object to have produced for this project. So my craft project ended up being the final product, with a few modifications– well, actually I had to make the whole thing over just to rearrange the parts a little, because the carpenter’s glue I’d used turned out to work too well. But the final prototype was still Dollarama wood, with a “real” knife instead of my razor-cleaver, and a wooden plate attached to the bottom of the dowel attaching the knife-swivel to the board, so it wouldn’t fall out. There was also a magnetized container added to the side. So, our final product was my first and last cooking vlog.
Project 3 was, in my opinion, the most interesting and useful of the four projects of the 1P13 course, as it consisted of a well-defined problem with clear metrics for evaluating how successful your design was. As in the previous project, the groups of students were divided into “Modelling” and “Computation” sub-teams, which had largely seperate goals, though the overall storyline justifying the assignment had to do with the two sub-teams combining their designs into a single system for sorting recycling.
Having done the computing sub-team for project 2, I was on the modelling sub-team for this project. The goal of the physical construction for this project was to design a mechanism that would use either a rotary or linear actuator to raise and lower the container on the upper part of a pre-fabricated hopper, so as to dump out recycled containers contained therein, as in these photos of the starting point provided in the assignment document:
Initially, each member of the group was tasked with coming up with different concepts of how this could be accomplished. My concept for how the linear actuator could be used was pretty much the simplest possible design… a stick. It’s a stick. It raises the top when the linear actuator retracts. Needless to say, I wasn’t exactly jazzed up about the challenges of making this one:
My design for how the rotary actuator could be used was, in my own humble opinion, cooler: it used a set of gears and a cam-and-follower setup to raise and lower the upper platform cyclically as the actuator rotated.
Unfortunately, once we compared this design to the actual size of the hopper our mechanism would need to fit onto, it was clear that the length of cam required to raise the upper platform to a sufficient angle to dump the recycling would not actually fit in the space we had available for the mechanism. actually, all three of us on the modelling team had generated one idea that was cool but impractical, and one that was less visually exciting but more likely to work, all of which were variations on the “it’s a stick, it makes the linear actuator push up” concept.
In the end, we settled on the most highly-developed version of the “it’s a stick” concept on the market, a scissor lift.
Next we needed to CAD it. Unless the thing is large enough that it makes sense to have different people working on different parts of it, which this wasn’t, it’s a little bit impractical to have multiple people “make” a CAD model of the same object at the same time; instead, the two of us who wanted to work on the CAD model both made our own versions, and we’d use whichever one ended up working better; and the member who preferred to work on fabrication, and had access to a private 3D printer, worked on that side. Unfortunately, the two of us who wanted to make a CAD model were both so enthusiastic about jumping into it that we failed to notice there were downloadable CAD files representing the already-fabricated parts of the hopper that you could use to make sure your mechanism would actually fit, and we showed up at the next class with two separate models of the mechanism, neither of which actually fit the parts provided. Oops! We fixed that for the next class and both attached our models to the given files. In an unexpected sudden death round of “who’s CAD model works better,” something went oddly and catastrophically wrong with the contraints on my classmate’s model, which had been working just fine, right before we were about to show it to a TA, so mine it was, kicking off a long iteration of files on my computer named things like “preminary CAD”, “final CAD”, “really final CAD”, “Actually final CAD after trying it IRL”, etc, as well as a large array of stray files featuring parts in amusingly unphyiscal situations:
(The one aspect of Project 4 that was unambiguously better than Project 3, for me personally: simply giving files version names… genius.) Anyway, “Actually final CAD after trying it IRL” looked like this:
The “after trying it IRL” part refers to changes made somewhat last-minute– the team member with a 3D printer being here essential– where we added a plate by which the slider at the top of the mechanism “hooks in” to the groove it’s sliding along. A previous version, right up until fabrication and testing, worked with the slider that runs along the top of the hopper essentially being held in only by gravity. This worked OK in the CAD assembly:
It actually stayed in pretty well in reality as well, but required a larger amount of force to get “unstuck” from its resting position when the actuator started to move. The fix was fairly simple, and only required re-fabricating one part; we decided to raise the slider rail off of the top with a few washers, and add thin pieces sticking off the slider that would be trapped between the slider rail and the hopper, so all the force of the actuator could only be translated in one direction.
Though there was no reason to think this would work any worse than the previous version, it was a little nerve-wracking in that we didn’t have the opportunity to actually test it on the real-life hopper until our final presentation. However, it fit in perfectly:
And when attached to the moving robot that it had been the computing team’s job to code, successfully put the recycling in the bin, at least the time that we were being marked on it:
As well as lucking out with excellent groupmates on this project, this was a fun experience because it involved a challenge that we wouldn’t necessarily have thought to set ourselves, with obvious standards of success or failure, and we had the fabrication resources to execute our design successfully. In making the CAD model (and re-making it… and re-making it…) I definitely learned some lessons that will (hopefully) make the next time I make something of this nature easier. For instance, an in-retrospect-obvious bit of planning that did not occur to me when I first started the model: why not just decide what size of screws you’re going to use based on what’s easily available at the hardware store, and then make your parts with holes of that size? Instead of doing that, by the end of the project I’d accrued a kind of CAD-cruft whereby the design included three different sides of holes: 4mm for the parts that needed to connect directly to the hopper, 3mm holes requiring screws that I drove all over town looking for, and holes for the dowels that started out 3mm and then had to be changed to match the size of dowel we ended up using.
Also, I learned to absolutely do not under any circumstances make changes to your parts inside your assembly file, even though that is a thing that Autodesk Inventor absolutely allows you to do, because then when you want to actually fabricate the parts, which requires exporting to a 3D-printable format from the individual parts files, you will have a bunch of parts that do not actually have the changes you want to have made to them, and when you ask a TA for help with that situation and explain how you got there, she will only shake her head sadly and say “Oh… dawg…”
We ended up dismantling the mechanism, because that thing had $40 worth of screws on it that I wanted back to be able to re-use, and the teammate who did most of the fabrication wanted to keep the other bits. However, we did each keep a single linkage, which now sits on my bookshelf as a souvenir:
The second project introduced the use of a virtual invironment built by Quanser. The project involved programming a robotic arm to pick up and put down boxes in various locations; since the actual robotic arms are expensive and delicate, the virtual environment allowed you to make mistakes without fear of damaging the equipment. Here was my final code for the task, which was to randomly spawn six boxes of different colours and sizes and then drop them off at a location that depended on the colour and size.
`ip_address = 'localhost' # Enter your IP Address here
project_identifier = 'P2B' # Enter the project identifier i.e. P2A or P2B
#--------------------------------------------------------------------------------
import sys
sys.path.append('../')
from Common.simulation_project_library import *
hardware = False
QLabs = configure_environment(project_identifier, ip_address, hardware).QLabs
arm = qarm(project_identifier,ip_address,QLabs,hardware)
potentiometer = potentiometer_interface()
#--------------------------------------------------------------------------------
# STUDENT CODE BEGINS
#---------------------------------------------------------------------------------
def pick_up_container(size):
if size == 'small': #if container is small, close the gripper a larger angle
angle = 35 #IF YOU CHANGE THESE ANGLES, ALSO CHANGE THEM IN DROP OFF FUNCTION
else: #if container is large, close the gripper a smaller angle
angle = 30
arm.move_arm(0.6, 0.003, 0.02) #trial pickup location-- could use improvement
time.sleep(2)
arm.control_gripper(angle)
time.sleep(2)
arm.move_arm(0.406, 0.0, 0.483) #this is the home position
time.sleep(5)
def rotate_qarm_base(colour):
positionsuccess = False
old_reading = 0.5
while not positionsuccess:
new_reading = potentiometer.right()
delta = new_reading - old_reading
increment = 348*delta
arm.rotate_base(increment)
time.sleep(0.2)
print(potentiometer.left(),potentiometer.right())
old_reading = new_reading
positionsuccess = arm.check_autoclave(colour)
if positionsuccess:
final_reading = arm.effector_position()
print("Arm is in position")
return final_reading
else:
print("Arm is not in position")
def drop_off_and_return(colour, size, final_reading):
arm.move_arm(final_reading[0], final_reading[1], final_reading[2])
arm.activate_autoclaves()
if size == "large":
arm.open_autoclave(colour)
else:
pass
print("Please move left potentiometer: between 0.5 and 1 for small, all the way to 1 for large.")
potentiometerused = False
while not potentiometerused:
if 0.5 < potentiometer.left() < 1 and size == "small":
potentiometerused = True
arm.rotate_elbow(-15)
arm.rotate_shoulder(35)
time.sleep(1)
arm.control_gripper(-35)
time.sleep(2)
arm.home()
elif potentiometer.left() == 1 and size == "large":
potentiometerused = True
arm.rotate_elbow(15)
arm.rotate_shoulder(30)
time.sleep(0.5)
arm.control_gripper(-30)
time.sleep(2)
arm.home()
arm.open_autoclave(colour, False)
else:
pass
def get_container_info(container):
if container == 3 or container == 6:
colour = 'blue'
elif container == 1 or container == 4:
colour = 'red'
else:
colour = 'green'
if 1 <= container <= 3: #Containers 1, 2 and 3 are small containers
size = "small"
else: #containers 4, 5 and 6 are large containers
size = "large"
return [colour, size]
def main():
import random
usedcontainers = [] #starts at length 0, will be populated with used containers
while len(usedcontainers) < 6:
container = random.randint(1,6) #gets a container with a value in the given range
if container in usedcontainers:
pass #We want to use each container only once
elif container not in usedcontainers:
arm.spawn_cage(container)
usedcontainers.append(container)
containerinfo = get_container_info(container)
colour = containerinfo[0]
size = containerinfo[1]
pick_up_container(size) #picks up the container
final_reading = rotate_qarm_base(colour)
time.sleep(0.5)
drop_off_and_return(colour, size, final_reading)
time.sleep(0.5)
time.sleep(0.5)
else:
print("Random value error!")
if __name__ == "__main__":
main()
#---------------------------------------------------------------------------------
# STUDENT CODE ENDS
#---------------------------------------------------------------------------------`
Modelling
Although I was tasked with writing the code for the concept, there was also a modelling and 3D printing aspect to the project, the idea being to create a box that the robotic arm could pick up and put down. Unfortunately, because of constraints on the availability of 3D printers, print time had to be kept under 2 hours. Since most large 3D print jobs take much longer than that, the box had to be scaled down until it was, shall we say, very cute. However, getting to use the 3D printers did provide an interesting view of how they work. The first print job failed, with the first few layers of the box looking like this:
After a quick consultation with my spouse, who works at the Makerspace at the public library and helps with the 3D printers (and embroidery machine, and laser cutter, etc– did you know the public library could do all that?), it seemed that there wasn’t a fundamental problem with the design (I had thought at first that there were too many holes in the box, and the filament wasn’t able to trace them accurately.) Instead it was just an adhesion problem, and could be fixed by either trying it again or, to be sure, using a glue stick on the printer plate. The next try was successful:
…yeah, it may not look like much, but… OK, there’s no but to that sentence. If we had the ability to fabricate metal, it could have worked– the idea, not exactly clear from a very quick CAD example, would be to have a fork that used a little spring to move a circular wraparound knife up and down; so you can stick the fork into the food, push the knife down to cut a piece of food around the tines, retract the knife (have it held up there or covered somehow so it’s not pointing at your face?), then use it as a fork. As it is, fork tines aren’t a good candidate for 3D printing because they need to get very thin, laser cutting can only cut flat parts along a single plane, and we would have no way of fabricating a circular knife. So, cutting board it was. A groupmate made a cardboard version of the concept, which a) holds the tip of the knife in place, b) has a slide to push food off the board, and c) has a container on the side for the food to be pushed into.
After this, we spent quite a while trying to figure out how to fabricate a better version with the resources available. The two methods of fabrication available through the class are 3D printing and laser cutting of acrylic. Most of the components we needed were long and flat; theoretically candidates for laser cutting, except that they were longer than the sheet of acrylic that each group was supposedly limited to. (Later we learned that the stated limits were more guidelines than actual rules, but that wasn’t officially circulated information.) Of course there are ways to buy all sorts of these materials, such as a knife– but aren’t we supposed to be, you know, making a thing ourselves? What level of “fabrication” was even expected of us? There was supposed to be a $100 limit on materials, but of course rumours swirled– “I heard that group spent $300 on electronic components and clamed they’d had it all lying around the house,” etc– and direct questions about the expected balance between a professional-looking product and a product we actually fabricated ourselves were met with apparent alarm and confusion.
If it’s not clear– there are straight razor blades sticking out of that cleaver-looking thing. My groupmates found this very funny when I brought it to class the next session.
