Stef,
The beam shapes shown in the datasheet are correct.
The sensor has a long-range detection distance and a narrow beam.
It was a lot of work to design the sensor but, not impossible.
The MaxSonar-EZ1 is not a copy of anything else out there. It is an
original design, designed to overcome the above mentioned problems and
much more.
The MaxSonar-EZ1 has a stable range output. It has a very narrow beam
and has long range. It works to look down a hall or in my living room
or in a robot contest.
I also started with two sensors, but it was not possible to detect to
zero so I switched to just one sensor. In addition, two sensor models
have a blind spot in between the sensors as one gets closer. Again I
did not what the sensor to have a blind spot.
I noticed the mentioning of Devantech Ltd. on the bottom of your page.
To this I respond with the text below. (The text below I posted on
another group and further addresses your comments.)
One of the reasons I completed this sensor was because my daughters
robot was stuck on a wall (it was too close) during a contest. The
sensor that was on the robot was one of most popular two sensor models,
but when too close, it was blind.
I then purchased one of all the popular robot ultrasonic sensors and
found problems with them all! I was looking for a solution to the
range sensing that didn't cost and wasn't big. I was willing to invest
to find the one that worked... One at a time, I tried them.
The next problem was that this dual sensor beam width was much too wide
to be useful. The (smallest?) dual sensor model that I have has a beam
width so wide that it detects a wall, a full 180 degrees, one meter
away. I literally could not use it, for anything!
The other dual sensor high end model with I2C, that I have, has
readings that vary so much, during the first one meter, I have to
average many readings just to get a stable reading. It is not
uncommon to have readings vary more than 6 cm and sometimes 15 cm. It
also has a beam width that was over two meters wide just one meter out.
Again the beam width is too wide to be used in my home! I can not
use it down the hall or in the living room!
Another recent dual sensor model has a narrow beam width, but has
trouble with small objects and has a short range.
No offence really, it is just that I want a sensor that actually works.
(And I didn't really want the $100 analog output, high current models,
and too big for a small robot. I did find that these expensive round
ones actually worked though.)
I found I could not purchase a low-cost, small, low-power sensor that
actually provided a stable range output.
So I built this one.
For you guys that don't know, along with the design of the beacon
system for the original Robot Wars autonomous class, I contributed the
battery chapter in Build Your Own Combat Robot. Although my name, some
of my work, and some pictures of my robot are in the book, the chapter
on batteries is all that I did for the book, the other stuff was
gathered and so some of my other work made it into the book. And I
also critically read another chapter of the book for the editor before
publishing.
Bob Gross
