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We have some important news to share about HackSpace: Issue 81 was the last issue of HackSpace as a standalone magazine, and HackSpace has become part of The MagPi, the official Raspberry Pi magazine. Starting with issue 145, We’ll be adding pages to The MagPi to make room for the stories and tutorials you’ve come to expect from HackSpace.

Wrap a computer around it

By Bunnie Huang. Posted

My doctoral thesis advisor, Dr. Tom Knight, imparted upon me many valuable pieces of wisdom. One aphorism was “wrap a computer around it”: instead of making a system more perfect, it’s often cheaper to use a computer to compensate for the imperfections.

For example, instead of making storage media absolutely perfect, it’s cheaper to throw a rather sophisticated processor into every hard drive or SSD that can compensate for the natural imperfections – and the inevitable degradation over time – inherent in physical storage media. The laws of nature conspire against highly ordered, perfect systems, so it’s cheaper and easier to accept the natural state of things and simply compensate for the bits that we find undesirable.

Motors are another everyday object that are difficult to perfect, but essential to everyday life. Subtle imbalances and asymmetries of a motor’s construction can lead to excess vibration and efficiency loss. While solutions exist to ‘wrap a computer’ around these problems, quite often the computer and the motor are two separate entities. However, in recent years, Moore’s Law has progressed to the point where microprocessors and sensors, powerful enough to ‘close the loop’ around a small brushless DC (BLDC) motor, can be essentially hidden within the motor’s physical size and power envelope. For negligible extra power and mass, a small computer can be wrapped around such motors to make them behave closer to ideal elements.

A good example of this principle in practice is a motor recently launched by a company called IQ Control. The smart BLDC motor incorporates a computer and sensor suite that enables it to consume 20% less power, while delivering 5% more torque. The internal computer also delivers smoother rotation by remembering the unique torque ripples inherent in the motor, and inverting the ripple during normal operation.

Drone enthusiasts reading this issue would also benefit from the faster response time enabled by the internal computer, allowing the motor to reverse direction much faster than conventional ESCs that rely solely on back-EMF for feedback. The net result is a more manoeuvrable drone, that can do tricks and flips without losing as much altitude.

One of the great things about computers getting so cheap and small (like the Raspberry Pi), is we can now use them to improve imperfect things with minimal overhead. Whenever I encounter a physical engineering problem that’s chasing perfection, I take a pause and consider – could I wrap a computer around it and make it better for less?

Bunnie Huang

Andrew ‘Bunnie’ Huang is a hacker by night, entrepreneur by day, and writer by procrastination. He’s a co‐founder of Chibitronics, troublemaker‐at‐large for the MIT Media Lab, and a mentor for HAX in Shenzhen.

https://twitter.com/bunniestudios

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