At this stage in my exploration of paper as an interface material for shape-changing interfaces, I have selected four potential solutions for actuating shape-change in paper interfaces. Namely, these are stepper motors, cam and followers, linear motors and muscle wire. Below, I’ll elaborate a little on each, and discuss its strengths and weaknesses as a technical solution.
What is it? A type of DC motor that works in discrete steps. It is a synchronous brushless motor where a full rotation is divided into a number of steps.
How can I use it for shape change? As stepper motors can be turned incrementally, they allow for discrete movement. A very precisely controlled shape-change interface could be created, with the turning motion moving interface elements in an arc.
What’s the problem? Stepper motors, while easy to scavenge from old scanners and CD-ROM drives, are less easy to operate using a microcontroller. I have been attempting to drive the motor from an Arduino board, but as the driver for the motor is contained in the integrated circuit board for the deconstructed device, this is not a simple process. Given my patchy knowledge of electronics, I am beginning to think another approach is needed.
How can I solve it? Get help, and buy components. I think I have over-complicated the process by re-purposing old steppers and their drivers. I am now planning on buying some components online following a tutorial. More expensive, but much simpler.
What is it? A sliding component which is belt-driven by a small motor.
How can I use it for shape change? The linear motion provided by this device is ideal for folding and unfolding paper. By fixing one side of the paper to the slide, and the other to the end of the component, accordion pleats can easily be expanded and contracted.
What’s the problem? Limited range. The linear motor can only move the length of its track, which is approximately 5 inches.
How can I solve it? Multiple linear motors could be used. Extensions could be added to these to increase the range. Several linear motors could also be layered up to permit motion along several axes.
What is it? A nickel-titanium alloy that can flex and contract when a specific amount of heat or current is applied to it. Get more info here: http://www.chymist.com/Nitinol.pdf
How can I use it for shape change? It could be woven through paper folds to expand and contract in infinite varieties.
What’s the problem? Cost. Although it is widely available online, there are large shipping costs attached to shipping to Ireland, plus a not insignificant wait time. In addition, there are many varieties of this wire available, with different technical specifications, making it difficult for an amateur to know what to order. This adds to the cost issue, as I would really want to know what I’m doing before I order anything.
How can I solve it? Get help from clever people. I’ll be turning to any electrical engineers and makers that I know to help me with this one.
Cams and Followers
What is it? A cam is a mechanical device used to transfer motion to a follower. In a cam follower pair, the cam normally rotates while the follower may translate or oscillate.
How can I use it for shape change? This mechanism could be attached to motors to turn circular motion to linear motion.
What’s the problem? The more mechanisms that are added to paper interfaces, the bulkier and more complex they become. My ideal design can be interacted with in an effortless, intuitive manner. this may be achievable using mechanisms such as these, but it would perhaps require some thought.
How can I solve it? Clever designs that mask mechanisms. However, the feasibility of this solution will only become more apparent through hands-on explorations.