MaxSonar-EZ1 (a great ultrasonic sensor) is featured in three magazines!

Clifford, I found your web page. Your circuit and observations are very cool! I did something like this in 1994 & still have the electronics and
paperwork sitting around somewhere. At the time the cost of using a 68HC11 and multiple opamps (without using spice to design) made the design somewhat costly. Lindsay Kleeman's work was (and still is) very good reference material. His very important work showed that this 3D stuff worked and could be very accurate.
Bob Gross
Clifford Heath wrote:

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Bob (Robot Wars Thumper 1997) wrote:

No single sensor will provide valid data in all instances. Far too many variables in the physical world. This is why we humans have five senses, and why most of the better robots incorporate proximity, distance, and touch detection as basic means to navigate an environment.
While I'm not saying the EZ1 isn't a welcome addition to the collection of inexpensive ultrasonic rangers available for amateur robots, wouldn't you say the product might also not exist had your daughter's robot also included a simple IR proximity sensor (Sharp OPIC type) or even whisker switch?
-- Gordon
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You mention "wouldn't you say the product might also not exist had your daughter's robot also included a simple IR proximity sensor (Sharp OPIC type) or even whisker switch?"
True, if my daughter's robot had one of these other sensors I may not have had the passion to put this effort into this project. I could have pulled the sensor away from the front of the bot, I could have switched to IR, or I could have even used a simple bump sensor. I just felt that it was possible to detect to the front sensor face, even pressing against the front sensor face. To me, wining robot contests was not the challenge here, but making a better sensor was.
What is funny, is that it was a design goal (hobby based) to detect to the front face, even pressing against a wall. This was not possible with dual sensor models, but with dual sonic sensors I built, I was able to detect closer than 1mm, but when I moved closer, the sensor stopped detecting the presence of the wall. My repeated measurements of all the ultrasonic sensors mentioned and others showed that 1mm was much better than the others, but I was doing this as a hobby, and as a design challenge to myself, so I then moved back to the single sensor design. I wanted to detect up to and touching the front sensor face. The math and circuit simulator showed this was possible for a single sensor model.
History (cutting out previous to 2004) In early 2004 I built up the first single sensor PCB. In early 2004, I found it very difficult to get useable up close data from a single sensor model. From spring of 2004 though February 2006 I built up about six separate dual sensor models at a cost upwards of a few thousand dollars. (I ordered PCBs, sensors, more sensors, design tools, ect.) Each dual sensor model was working better than the previous. This initial work was done as a hobby. I am a high end electronics and software engineer in my day job, where I both write design instructions and participate and do the actual design/prototype work, so I can do this type of thing as a hobby and actually enjoy it! (Even buzz, like this form, is kind of fun.) The MaxSonar-EZ1 came out of a six week stay away from my family (for day job related reasons) when I would work this problem, every night from about 5:30 to midnight. It was here during midnight hours that I cracked the door to the actual problems and found solutions. Not easy, but kind of fun, in a challenging sort of way.
Cheers!
Bob Gross CEO MaxBotix Inc.
Gordon McComb wrote:

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Bob:
It's your decision for your product, but I'd rather have a blind spot than the required startup distance. I can measure distances that are right near the robot with a switch.
As it is, to use the Maxbotics sonar in a real robot I have to have some fairly complex circuitry to do a power-reset when I *know* the sonar has suffient clear space. I don't always have the luxury of knowing where my robots are when they start up. Nor do I always have the ability to always make sure that there is clear space around the robot at startup even when I do know it's location.
Bob (Robot Wars Thumper 1997) wrote:

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D. Jay Newman ! Author of:
snipped-for-privacy@sprucegrove.com ! _Linux Robotics: Programming Smarter Robots_
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Bob:
Are you saying that if I don't care about detecting objects within 6 inches that it doesn't matter if I have the stated distance at power-up?
Also, a pin to cause a reset would have been nice so that I could reset it once I was sure that I had the proper distance. Other than this start-up distance you have a nice sensor. I have 5 or 6 of them now.
And I'm glad that you're doing well. I've seen your product carried in *many* places, and seen the ads in the various magazines.
Bob (Robot Wars Thumper 1997) wrote:

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You mention, "Are you saying that if I don't care about detecting objects within 6 inches that it doesn't matter if I have the stated distance at power-up?"
It is true that if you do not need or care about operation closer than 6 inches then just power up and use the sensor. Also fif you want to delay the calibration, just delay taking the first reading.
Future Features I really like the idea of providing both polarities of serial output. The real problem has to do with so much already being done in the software that code space is at a super premium. And because there are two camps, those that like the serial output as is (for example, with a rotary switch and a DB9 connector, one can verify operation of the MaxSonar-EZ1 sensors at any time with a PC and hyper terminal) that I would need to keep both. I am trying to find out if this change (allowing for both serial polarities) will be possible in the software. Don't get your hopes up : ), but I am really looking into this. The code can be cleaner and so I do not have an answer as of yet. (This is being done along with my other tasks, but it is important to me.)
I really like the idea of allowing the user the ability to command again the calibration of the ringdown as they desire. I have been hearing this every so often, and this change would not be code intensive. When the user detects objects past 14 inches, then they could command a ringdown calibration. (Before the release of the MaxSonar-EZ1, I actually worked for many months to try to implement this automatically, but I was always able to set up a scenario, where if done automatically, the scheme did not function. People that attend the robot group I attend know that the sensor can measure much closer than 6 inches, (but it is not included because this is not alwyas relaible, every day in, and day out. Getting reliable data that always was accurate and never varied, was and remains a strong design goal.)
Bob Gross CEO MaxBotix Inc. www.maxbotix.com D. Jay Newman wrote:

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Bob (Robot Wars Thumper 1997) wrote:

That does make sense, even though it requires an output pin to deal with that, though that is much easier than the circuitry that I was thinking of. For some reason I thought that the calibration happened at power-up.

That would be my major wish.
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Thanks for your comments! We are doing well, but it could be sometime into next year before we actually turn a profit. We end up paying back a little every month. Our profit margins are purposely kept low because we desire to be a service company to everyone, from hobbyists to the OEMs. MaxBotix Inc. incorporated July 1st 2006 and purchased the small assembly house that builds the MaxSonar-EZ1 mainly to keep high volume costs low. Again all this costs money, but we have actually been lowering our high volume prices.
Very glad you like the sensor!
Cheers,
Bob Gross CEO MaxBotix Inc.
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