“Did I forget something?” It’s that nagging feeling every engineer has when their project is about to be deployed – it may be a product about to be ramped into production, a low volume product, or even a one off like a microsatellite. If you have the time and a few prototypes to spare though, there are ways to alleviate these worries. The key is a test method which has been used in aerospace, military, and other industries for years – Highly Accelerated Life Testing (HALT).
How to HALT
The idea behind HALT testing can be summed up in a couple of sentences:
Beat your product to death.
Figure out what broke.
Fix it, and fix the design.
Sounds barbaric, and in many cases it is. HALT testing is often associated with giant test chambers which are literally designed to torture anything inside them. Liquid nitrogen shock cools the chamber as low as -100°C. The Device Under Test (DUT) can soak at that temperature for hours. Powerful heaters then blast the chamber, causing temperature rises of up to 90°C per minute, topping off at up to 200°C. Pneumatic hammers beat on the chamber table causing vibrations at up to 90 Grms and 10 KHz. Corrosive sprays simulate years of rain and humidity. These chambers are literally hell on earth for any device unlucky enough to be placed inside them. It’s easy to see why this sort of testing is often referred to as “Shake and Bake”.
Makerspace North is unique out of the 5 makerspaces in the Ottawa, Canada area in that it started life as an empty 10,000 square foot warehouse with adjoining office spaces and large open rooms, and has let the community fill it, resulting in it having become a major hub for makers to mix in all sorts of ways, some unexpected.
Many makerspaces are run by an organization that provides tools that groups or individuals use, along with qualification courses for select tools. Makerspace North, on the other hand, provides the space and lets the community provide the maker component. The result is a variety of large scale events from indoor drone flying and various types of maker faire style days, to craft shows, garage sales, and even concerts. Smaller meet-ups, most often open to anyone, are held by such groups as the Ottawa Robotics Club and the Ottawa Electronics Club as well as some more general ones. Courses offered by the community are also as varied.
This also means that the owners of Makerspace North don’t provide tools for people to use, but instead provide dedicated rental space. That doesn’t mean there aren’t tools — it means that Makerspace North encompasses a microcosm of various renters who fill out the task of things like tool rental. This is just one example of how the community has embraced the unique approach. Let’s take a closer look at that and a few other novelties of this system.
Homebrew laser cutters are nifty devices, but scorching your pals, burning the house down, or smelling up the neighborhood isn’t anyone’s idea of a great time. Lets face it. A 60-watt laser that can cut plastics offers far more trouble than even the crankiest 3D-printers (unless, of course, our 3D printed spaghetti comes to life and decides to terrorize the neighborhood). Sure, a laser’s focused beam is usually pointed in the right direction while cutting, but even an unfocused beam that reflects off a shiny material can start fires. What’s more, since most materials burn, rather than simply melt, a host of awful fumes spew from every cut.
Despite the danger, the temptation to build one is irresistible. With tubes, power supplies, and water coolers now in abundance from overseas re-sellers, the parts are just a PayPal-push away from landing on our doorsteps. We’ve also seen a host of exciting builds come together on the dining room table. Our table could be riddled with laser parts too! After combing through countless laser build logs, I’ve yet to encounter the definitive guide that tells us how to take the proper first steps forward in keeping ourselves safe while building our own laser cutter. Perhaps that knowledge is implicit to the community, scattered on forums; or perhaps it’s learned by each brave designer on their own from one-too-many close calls. Neither of these options seems fair to the laser newb, so I decided to lay down the law here.
Last week the Supplyframe Design Lab in Pasadena opened it’s doors, welcoming in the community to explore the newly rebuilt interior which is now filled with high-end prototyping and fabrication tools and bristling with work areas to suit any need. I had a chance to pull a few people aside during the opening night party to talk about how the Design Lab came about and what we can expect coming out of the space in the near future.
Opening night was heavily attended. I recognized many faces, but the majority of those exploring the building were new acquaintances for me. This is likely due to a strong connection the Design Lab is building with the students, faculty, and graduates of the ArtCenter College of Design. Located just down the road, it is one of the top design schools in the world.
In 1988, a bunch of engineers from Hotzenwald, Germany, came together and decided that it is time for the future of mobility: A new, more modern and environmentally friendly car should put an end to fossils and emissions while still being fun to drive. “It should become a new kind of car. Smaller, lighter, cleaner – and more beautiful” is how future CEO Thomas Albiez described his mission. For the first time in automotive history, this series car would be designed as an all-electric vehicle from the start and set a new standard for mobility. The project was given the codename “Hotzenblitz” (“Hotzen Bolt”) to indicate how the idea came to them: Like a lightning bolt. The snarky regional term also came with a double meaning: Imaginary lightning bolts, used for insurance fraud.
Unnoticed by the rest of the world, they founded Hotzenblitz Mobile. Industrial Designer Harold Schurz was contracted to design the chassis for the Hotzenblitz, which was then modeled into a prototype chassis. The self-funded team moved fast. An external motorsports company helped to develop the tubular steel frame, and soon their vision took on shape. After the team had fitted a motor and transmission into the frame, CEO Thomas Albiez himself installed the traction battery and drive train. The team felt confident with the result, and in July 1990, during an open house day in the office, they somewhat spontaneously decided to call Green Tech entrepreneur and chocolate mogul Alfred Ritter.
Alfred Ritter had experienced financial losses after the Chernobyl Disaster. Many agricultural regions, including several hazelnut plantations that were vital to Alfred’s chocolate business, were irreversibly lost to the fallout contamination. It was then when he turned to the green energy business, founding the Paradigma group to manufacture solar collector systems and pellet heaters. When Thomas and the team called, Alfred jumped on the idea of an electric car. In the same year, Alfred Ritter and his sister Marli Hoppe-Ritter became shareholders in the company and helped to finance the future of the Hotzenblitz.
Last fall, I grabbed a robot arm from Robot Geeks when they were on sale at Thanksgiving. The arm uses servos to rotate the base and move the joints and gripper. These work well enough but I found one aspect of the arm frustrating. When you apply power, the software commands the servos to move to home position. The movement is sufficiently violent it can cause the entire arm to jump.
This jump occurs because there is no position feedback to the Arduino controller leaving it unable to know the positions of the arm’s servos and move them slowly to home. I pondered how to add this feedback using sensors, imposing the limitation that they couldn’t be large or require replacing existing parts. I decided to try adding accelerometers on each arm section.
Accelerometers, being affected by gravity when on a planet, provide an absolute reference because they always report the direction of down. With an accelerometer I can calculate the angle of an arm section with respect to the direction of gravitational acceleration.
Before discussing the accelerometers, take a look at the picture of the arm. An accelerometer would be added to each section of the arm between the controlling servos.
BB-8 is the much loved new droid introduced in the 2016 movie Star Wars: The Force Awakens, though in my case from the very first trailer released in 2014 I liked it for the interesting engineering problems it posed. How would you make a robot that’s a ball that rolls along, but with a head that stays on top while the ball rolls under it?
BB-8 in 1st Star Wars: The Force Awakens trailer
Hamster in hamster wheel
To make the ball roll, the answer most people found obvious at first was to use the analogy of a hamster wheel. The hamster running inside makes the wheel turn. In the BB-8 building world, which is quite large, the drive mechanism has come to be called a hamster drive, or just a hamster.
For the head, it seemed obvious that there would be magnets inside the ball, perhaps held in place near the top of the ball by a post extending up from the hamster. Corresponding magnets in attraction would then be attached to the underside of the head, and balls (also mounted under the head) would keep the head moving smoothly over the ball.
The magnet approach for the head has turned out to be the method used by all BB-8 builders that I’ve seen. However, the hamster has turned out to be only one of multiple solutions. Since the original debut many different methods have been used in builds and we’re going to have a lot of fun looking at each separate approach. It’s almost like revealing a magic trick; but really it’s all just clever engineering.
Note that for the actual movie, a combination of 7 or 8 props and CGI were used. The official working BB-8s that are shown at various promotional events were built after the movie was made and as of this writing, few details of their construction have been released. One notable detail, however, is that they aren’t using hamster drives.
Below are details of all the different BB-8 drive systems I’ve seen so far that have been built along with how they work.