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Sonar heads for use on Blue2ROV


(Todd Sparkes) #1

Hello all. Has anybody had experience using the Imagenix 852 sonar head vs the Tritech Micron? What is the general opinion? There is also a non mechanical Echologger MRS900. Has anybody had an opportunity to try this brand of miniature sonar? Thanks


#2

I haven’t tried any of them but thanks for posting these, you saved me some time!

Just looking at the specs, the Tritech looks like the best option. The Imagenix needs a minimum supply voltage of 24V which is high unless you plan on running battery sets in serial. The Echologger looks good but it’s not immediately obvious whether it has topside software.

Have you made any enquiries into the prices? That of course will make a big difference!


(Todd Sparkes) #3

Sarawak, The Tritech is the most expensive by far running for $8000 to $10,000. The Imagenex is around $5000. The Echologger for model MRS900L is $4,990 (500m version). The Echologger uses GUI software. It also has an advantage that there is no mechanical moving parts so there is no chance of mechanical failure. I am curious to know if anybody has used these models.


(Pierson) #4

AUV guy here. Heard nothing good about the Micron, teams I know who have one regret getting it. The refresh rate is something like 0.5hz. Subs move a lot in 2 seconds. I have not talked to anyone who has used the Echologger mor Imagenex. I tried to talk to Imagenex a couple times, and never heard back from them. Their site looks straight out of the 90s, didint know if they were still in business. The Echologger looks interesting, when I was looking 18months ago I don’t remember seeing it. After looking at the specs of the Echologger looks like a micron clone. Just somethings to consider. Not to jinx things but we are working on getting an older BlueView in the coming months. Fingers crossed grants go through, but I think it’s a P900. Really excited to see the data we can get off of a MBIS. Though probably overkill depending on your application.


(Kevin) #5

+1 for Imagenex not emailing you back (I’ve had the same experience)

I’ve been out with Rusty when he trialed the 852 on a BlueROV2. We were in like 5 foot visibility. It worked…but not well enough for me to want to spend $5000 on it just yet. I’d rather have accurate seabed maps or side scan sonar mosaics and a positioning system.


(Pierson) #6

@kevink yeah Imagenex has some cool products, If only they would reply to email so people could know how much they cost and the specifics. I was looking at the 937A, and Pico-tech FLS-40 and 120, and the blue view units. But I agree, a DVL or other positioning system is a better investment, gives you far more functionality for the money.


(undersearobotics.com) #7

We’re the East Coast US reps for Imagenex. Let me know if we can be of help.


(Pavel) #8

Think Sensor Research Inc, specializes in industrial sonar systems, system solutions and navigation solutions for underwater mapping and structure mapping for the energy and transportation markets. Our company has over 100 years of combined sonar design experience. We are currently looking at possibly launching products into this ROV market at the $1000 to $2000 level. We are looking at possibly doing an initial run of 100 units, but we would need some market feedback and suggestions.on the following:

  1. The first product would be a general sonar block with electronics and a single sided transducer all in one that could be used as a side scan unit or sector scan unit if mounted on a rotator. The communications protocol API would be open and allow anybody to write software or interface to it, no proprietary interfaces. These blocks could also be used in pairs providing side scan coverage to both sides of the ROV.

  2. Communications, we are looking at RS232, RS485 and/or Ethernet, what would be the most useful?

  3. Frequency vs range, there is a general trade off between range and frequency (resolution). The frequencies that we are currently considering are 300 kHz, about 200 meter range and 450 kHz around 100 meter range. Other frequencies are also possible. What frequencies would the market like?

  4. We are also considering an interferometric system that could produce bathymetry (for simple acoustic geometry) and image at the same time. Would there be an interest in this from the ROV community.

  5. What depth rating would be useful?

  6. What type of underwater connector?

We already have a basic sonar block which is a simplified version based on our multi channel industrial systems. We really feel that their is a real lack of a good sonar product with near industrial performance in this market and with an open interface specification.

We are planning testing on this new simple sonar block product over the next month.
What would you like to see example images of?

We are based around Vancouver, Canada so there are lots of good interesting targets around in the ocean around the city.

There are a couple of product market launch options that we are looking at. One of which could be be an indigo or kickstarter campaign for this product, what would you like to see before making a purchase? We would be aiming for a fall delivery of 2017.

Thanks,
Pavel Haintz, M.Eng,
Think Sensor Research Inc.


(Todd Sparkes) #9

Pavel, It is good to hear a company is looking at cost efficiency as well as a quality product. I read your post above. My answers are based on general ROV use but mostly mini-ROV such as Blue2.
Due to working over copper I believe RS485 two wire would be the only route to go for communications. RS285 would require an external RS232 - RS485 converter.
All ROV systems but especially mini-ROV systems (cageless) are more interested ranges between 20 meters to 50 meters. These are ranges which are accessible on the tether lengths in use.
Depth ratings for most mini ROV systems would not have to be over 100 meters. Taking in account overkill a 300m depth rating would be ideal.
Basing your proposal on cost the most cost efficient connectors would be either Birns or SEACON.
I believe images of items an ROV operator would normally see on a job would be most useful. Some items such as a pipeline, a cable, a vessel hull, a wharf, and even just some boulders on a flat seabed.
Personally I would be very interested in a unit for this price assuming it could produce a repeatable image in the 10 to 50 meter range.

Regards
Todd Sparkes
Calm Water Inspections


(Kevin) #10

Pavel,

That’s a really good price point if you can get in the $1000-2000 range. Here is my feedback for me personally, the devs will have something different.

  1. No real comment here other than I’m not much of a programmer, so whatever software is there is what I’ll use. I’m of the opinion that side scan is better for towfish and UUVs and scanning sonars are better for ROVs.

  2. I like Ethernet and I intend to run digital ROVs, but RS485 would probably have better comparability for the guys that run analog. As long as I can eventually just plug it into an ethernet switch on the ROV, I’d be happy.

  3. For scanning sonar, the higher frequency the better. I’d probably like one in the 650kHz at 50m range.

  4. Would the interferometric system be more or less accurate than a surface single/multibeam sonar? If less, probably not.

  5. 300m would be ideal. I don’t see many more people operating small observation class ROVs past that.

  6. I think BR is coming up with some sort of connector here soon. Everyone argues that the Seacon Micro WET-CONs are expensive, but I like those.

My target sizes these days seem to be around 3-4m or so on the seabed so if you can pick up something that size or smaller with decent resolution to give me some idea what I am looking at in really poor visibility, that would be great.

Kevin Klemens
Endurance Marine Exploration


(Roy Petter Dyrdahl Torgersen) #11

The first product would be a general sonar block with electronics and a single sided transducer all in one that could be used as a side scan unit or sector scan unit if mounted on a rotator. The communications protocol API would be open and allow anybody to write software or interface to it, no proprietary interfaces. These blocks could also be used in pairs providing side scan coverage to both sides of the ROV.

Cool. Open source / Open APIs are the way to go!

Communications, we are looking at RS232, RS485 and/or Ethernet, what would be the most useful?
Ethernet

Frequency vs range, there is a general trade off between range and frequency (resolution). The frequencies that we are currently considering are 300 kHz, about 200 meter range and 450 kHz around 100 meter range. Other frequencies are also possible. What frequencies would the market like?

Frequency, I would aim for even higher resolution. 900 kHz is often used in SAR applications. I could probably sell quite a few of those.

We are also considering an interferometric system that could produce bathymetry (for simple acoustic geometry) and image at the same time. Would there be an interest in this from the ROV community.

Depends on how much the price hikes. I think a v0.x on crowdfunding should be MVP.

What depth rating would be useful?

I concur with @canman172 and @kevink at 300m

What type of underwater connector?

No connector needed. just go for bare wire. Each ROV technician can then use their preferred connector (we would probably use the Blue Robotics penetrators)


(Tim Pierce) #12

A sonar in that price range would be awesome. Ideally I would personally like one rated to 938 feet depth.

  1. A “depth to keel” downward rov altitude transducer would also be useful, the others all sound useful too. If you have proposed dimensions someone might make 3d printable adaptors for a blue robotics hull.

  2. Most of our tethers are going to be copper, have at least 2 or 4 unused wire pairs at essentially cat 5e rating, something that can be sent 2 over wires with at least 450 foot transmission range would be ideal.

  3. I would want sonar for finding things in poor visibility. I would possibly have a boat mounted system you get the rov close, and then guide the rov closer on its own.

  4. Yes, very much.

6, ideally something that could integrate with our tethers. A 2 pin sea con connector perhaps?

I’d like to see some sample images of a wreck, maybe some other standard is shapes like a piling or an anchor?

Things I would want to see personally is a price tag closer to the $1,000 mark than 2k, even if it was a base unit that you could later add modules to as funding permits. I would want to see the hardware on something similar size to a bluerov 2 (or an actual bluerov 2) . I would also like details on weight, any tendency to float, mount dimensions, sample images and video, and the topside interface setup.

Let me know if you need testers near the other Vancouver!


(Rusty) #13

Wow! This is a cool thread. I want to toss in a few comments.

We’ve used the Imagenex 852 mechanical scanning sonar. It was really easy to integrate with the BlueROV2. The software leaves some to be desired but it works - we found it to be really picky with regards to RS485-USB converters. The performance is alright and works well enough for navigational purposes in environments when there is stuff to see.

Their newest 852 units can actually run on 12v up to 48v (I think - don’t quote me on the 48v). We run it directly from battery voltage on the ROV.

Contrary to what everyone else said, Imagenex has been very responsive to us and shared a lot of information. Bummer that they haven’t done that with everyone.

I’ve chatted with @phaintz at conferences and he’s a great guy and very enthusiastic to provide some low-cost solutions in this market. Thanks to everyone who shared their thoughts for him. Here are my thoughts:

  1. I like the “block” design with an eye on reusability in a wide variety of situations from 360 scanning to side scanning. Side scanning from ROVs is relatively rare because it requires driving in a very straight line, but that would actually be pretty feasible on a BlueROV2.

  2. RS485 is easiest to integrate. I’d also consider integrating a Fathom-X directly into the module so that you have two-wire Ethernet data. That could be connected to the same twisted pair as the main Fathom-X for the ROV.

  3. I think shorter range and higher resolution is best for a small ROV.

  4. Interferometry would be cool if it doesn’t boost price too much.

  5. We’re designing most of our future products for at least 300m.

  6. Like Kevin mentioned, we’re doing some work on connectors, so I’d recommend saving that decision for later :wink:

Also, I’d be very hesitant to launch something like this through Kickstarter or Indiegogo. I’m not sure it fits into the crowdfunding model very well.

-Rusty


(Pavel) #14

Thank you very much everybody for your responses and suggestions.

We do have some ceramics in stock to make 300 kHz single channel arrays. The first run of single channel sonar blocks would have the following preliminary specifications.

  1. Approximate mechanical size would be a block approximately 15 cm x 10 cm x 5 cm
  2. RS485 for initial simplicity
  3. 300 kHz for the initial transducer. For the interferometric version our current limit is 450 kHz. For the single channel version we could go up to 1 MHz.
  4. Two channel interferometric receviver would be for the next version. The second channel adds significant cost to the construction and testing of the transducer array. The ceramics have to be very accurately placed and aligned for interferometry to work correctly The electronics adds a bit more cost but not too much. The interferometric sonar would still be under $2000.
  5. Depth rating on would be at least 300 meters.
  6. To keep the cost low for the single channel version we can use a penetrator with a cable for this version. What length of cable would be useful?

This 300 kHz single channel sonar block with penetrator would be under $1000. Our aim is to get a large market as possible while keeping the transducer and image quality very high.

We will see if we can come up with the some sample images and pictures of the initial version by May and we could be possible do an initial run of the single channel for the market by this summer followed be the interferometric by fall of this year.

I had very good discussions with Rusty and we will see if we can figure out a good way to make good sonars accessible to as many customers as possible.

Thanks,
Pavel


(Tim Pierce) #15

Penetrator cable length similar to the bluerov2 thruster cable length of about 3 and a half feet long would be useful for many of us, along with possibly a longer, un potted “build your own length” cable for those of us comfortable with potting cable glands.

What would be the theoretical difference in quality between the two channel and single channel versions? is it a range boost?

Of the ROV mounted block, how much of that 15cm x 10cm x 5cm needs to be unobstructed for the unit to function properly? I’m picturing some sort of large flat oval that mounts to the bottom of an ROV frame.

Once you get closer to production status, if you need any assembly allignment jigs or housings / cases / etc designed or printed let me know.


(Pavel) #16

The main difference between the two channel and single channel version is that the two channel version would provide angle of arrival of the acoustic wave, giving bathymetry (point cloud) for simple surfaces, no complex structures, which have multiple angles of arrival and require multi-channel phased arrays. Both the single channel and two channel would provide image data. The image on the two channel version maybe slightly better because of the ability to average out the two receive signals on two channels.

On the sonar block about 12 cm x 5 cm would have to be unobstructed.


(Tim Pierce) #17

Ok, that shouldn’t be too hard to build into a ROV frame at all. Any idea what kind of mounting pattern you are thinking about? will it have integral mounting bolt holes on one side? mounting tab flanges? Also it would be useful to know how close landing skid legs could be to the edge of the unit (will a landing skid that extends down 3cm below the edge of the unit but is 15cm away from that edge interfere with the scan in a downward facing “side scan-ish” configuration? Or would the intent be to mount it facing forward like a searchlight?


(Pavel) #18

Currently we are looking at mounting tab flanges, two on each side of the sonar. Bolt mounting holes would also work, but in Aluminum they tend to strip very easily. This sonar block would be usually mounted like a sidescan sonar, with a 45 deg tilt to the side, or on a rotator facing forward for sector scan configuration. Mounting the block forward would probably not result in useful data. For how close the landing legs can be mounted, the beam width for the 300 kHz array is 2.5 deg x 60 deg, so think of a fan starting in the center of the array. The 60 deg is perpendicular to the length of the array.


(Harold Scadden) #19

Helicoils are your friend when it comes to mounting stuff in Aluminum. I make tons of molds with 6061 and we use them to keep from striping out the soft metal. The biggest thing you are going to have to deal with is cathodic corrosion so I would make a real good choice if you decide to use them.


(shujun wang) #20

You can try to use raspberry pi complete the RS485 process, and the data passed TCPIP to the PC