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New Ultrasonic Range Sensor

Discussion in 'Electronic Components' started by Bob (Robot Wars Thumper 1997), Jan 4, 2006.

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  1. All,
    I have been working on an ultrasonic sensor since 1994.
    (Time to shoot the engineer!)
    About two years ago I decided to package the sensor for everyone.
    It is avaible now. Data sheet is avaiable at the web site.

    www.maxbotix.com

    The MaxSonar-EZ1:
    is very low cost,
    uses just one trasnducer,
    detects to zero (yes even pressing against the front face),
    detects to 254 inches (6.45 meters),
    is the smallest size (smallest PCB & includes mounting holes),
    is the lowest power (just 2 mA typical at 5V),
    has a controlled narrow long-range beam,

    has a very easy user interface including RS232C, pulse width, and
    analog votlage.

    I posted this because this really is a break through product
    and I would have wanted one in 1997.
     
  2. Stef Mientki

    Stef Mientki Guest

  3. 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
     
  4. 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
     
  5. cbm5

    cbm5 Guest


    The easy solution, of course, is to set the ultrasonics back from the
    edge of the robot so the blind spot starts within the measurements of
    the platform. Then utilize bumper switches or short-range IR to detect
    zero-distance objects if necessary. Not too elegant, but straightforward
    enough.

    However, you chose the hard solution, and I have to applaud you for
    that. Instead of giving up on the fully ultrasonic sensor you've created
    something that will be helpful to many robot builders and other distance
    applications in the future. I'm sure the big guys are dropping their
    teeth about now upon seeing your single-transducer solution and low price.

    One question I have, if it's not too much trouble: any chance of adding
    one or two more bits to the distance resolution, or calibrating for a
    shorter distance with smaller increments? I realize timing is probably
    tight in your microcontroller but additional resolution could turn out
    to be handy sometimes.
     
  6. This was my Rubik's cube... It was time to shoot the engineer and ship
    the product. With an engineering mind we can add many features, but
    low cost, means a uC with very little room. I packed it good! 10-lbs
    in a 1-lb sack! But who knows...

    Bob
     
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