New Ultrasonic Range Sensor

Nice sensor, but your beamshapes, given in the pdf, seems to be physical impossible.

And if you want to measure (not only detect) downto 2 cm ( All,

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

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

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.

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