Page 27 - Build Your Own Quadcopter_ Power Up Your Designs with the Parallax Elev-8

6 Bu il d Y o ur O w n Q u a d c o p t e r

The Latin words at the start of the court’s decision refer to English common law where
it was held that a landowner had exclusive rights to all space “from the depths to the
heavens.” Obviously, the court held that this specificity did not apply in the United States.
Otherwise, one could imagine the resulting chaos if airlines had to obtain landowners
permission to fly into airspace that projected from the ground. As mentioned earlier, it
would be wise to check with the appropriate authorities before flying your quadcopter in a
country other than the United States. You might find yourself inadvertently trespassing in
someone’s airspace.
Other limitations or constraints related to real-time video surveillance are more
problematic. All quadcopters with video capability, whether onboard capture or real-time
transmission, should be operated with prudence. In other words, it is definitely not a good
idea to fly the quadcopter (even without video) over to your neighbor’s house and attempt
to peer in their windows. Flying over your neighbors' houses, while legal, should be done
with an abundance of caution. I would definitely talk with my neighbors prior to making
any flights above or close to their homes.

Design of the Elev-8 Quadcopter

According to Ken Gracey, President of Parallax Inc., the Elev-8 project began after a visit
to his company by some folks from the Hoverfly Company. Hoverfly manufactures
sophisticated quad and hex copters that can optionally be equipped with camera systems.
Hoverfly also designs and manufactures flight-control boards, which was one of the main
reasons they visited Parallax. It turns out that some very bright Parallax engineers designed
an unusual and very clever eight-core microcontroller they aptly named Propeller. The
designers decided to call their cores “cogs,” which I suppose was to emphasize a more
collaborative computing approach as compared to traditional multicore processors. (In a
later chapter, I will explore the Propeller chip in much greater depth.) Designers and
engineers at Hoverfly recognized the unique capabilities of the Propeller chip and decided
to incorporate it into their flight-controller boards. Thus, the reason for the visit to Parallax
headquarters was to demonstrate their quadcopter. Ken was fascinated with their
demonstration and quickly realized that he and his company had to be involved in a like-
minded project, which is the genesis of the Elev-8. Ken also realized that it made much
more sense to provide a kit of parts in lieu of a fully assembled quadcopter. This idea
fit with the Parallax company specialty, which is centered on providing builders and users
with components and subassemblies in lieu of fully assembled products. At times, they
have provided fully assembled products, but that seems mostly outside of their modus
operandi.
Creating the basic Elev-8 kit was in itself a bit of a problem: Ken and two of his engineers,
Kevin Cook and Nick Ernst, had to determine suitable components that would enable
builders to successfully make their own Elev-8 without excessive costs or complexity. Many
of the problems and design decisions they encountered will be discussed in later chapters to
provide you with an understanding of the decisions that are required in a project of this
complexity.
It was an easy decision for Ken to simply incorporate a fully assembled HoverflySPORT
controller board into the kit. The flight-controller board is the key element that enables a user
with an R/C transmitter to fly a quadcopter as directed. Figure 1.6 shows the HoverflySPORT
controller board.
Chapter 2 delves into the complexities of quadcopter flight dynamics, and it soon will
become apparent that designing and building a flight-control board is best left to professionals.