Ping2 sonar gives incorrect data at close range

Blue Robotics Products Ping Sonar Devices
1

Hello dear friends. We purchased the “Ping2 Sonar Altimeter and Echosounder” device. When our vehicle is very close to the wall of the pool, the received data is extremely large, and the reliability is high. How can we prevent this?

2

Hi @berkant -
By “reliability” do you mean the confidence estimate? This may be due to multi-path reflections in your pool, and is somewhat unavoidable if so… In open-water environments, it should not occur!

3

Thanks for answer. We will try algorithmic solutions.

4

Hey @berkant we are trying to accomplish a similar project of mapping a swimming pool using the Ping2 for obstacle avoidance.
Were you able to come up with any algorithms to solve the issue, or have any suggestions of where we should start?

5

Hi @berkant and @ben1219925 -
Setting the maximum range the Ping2 is searching within to detect the bottom may help reduce the risk of multipath interference!

6

Hey all,

We’ve been having some issues with this in shallow reef environments across a range of ping2 units for bluerov and blueboats. The issue presents as a depth reading thats very high (eg 90 metres) when its in the order of 2 to 3m. It does this with very low confidence, and will periodically switch between these bogus values and the correct ones, with no clear pattern i can discern. Sometimes it does it at all the times, sometimes barely so when running missions back to back.

Is there any way we might be able to correct for this in post? I note looking at the pingview output that the surface is easy to see in the return but for some reason it calibrates to a really deep reflection.

7

Hi @Vincent -
The SimplePing Survey extension will record the confidence value, so you can simply filter out results with low confidence…

As for your issue, beyond setting maximum range manually, there may not be much you can do without modifying the Ping firmware - this will soon be publicly released / possible to do.

Decreasing your survey speed in the meantime may improve the situation?

8

Hey Tony,

I thought as much. Slowing down survey speed isnt really feasible.

Wil tet manually setting the limit amd see if it helps

9

Hi Tony,

We are currently testing in a pool with a depth of 4.4 meters. When the unit reaches the bottom, the confidence values are not stable at 100% and are fluctuating between 0% and 100%. Because of this variation, we are unable to obtain an accurate depth reading.

Kindly advise on the possible cause of this issue and suggest the steps required to correct it. Please also let us know if any specific calibration, configuration changes, or additional checks need to be performed from our side.

10

Hi @mageshn -
The Ping single beam sonar lists a minimum range of 0.3 meters - this is true in ideal conditions. In a pool or tank, even with generous size, reflections of the sound energy can confuse the math that is estimating range and confidence. You could try lowering the gain manually, or flash an open-source firmware for the unit and explore improving the code to perform in your application (assuming you’re not just testing, and headed to open ocean in the future where performance may be greatly improved…)

11

@Tony White We are currently using your altimeter (Ping-based sonar) integrated on our ROV for depth measurement in a 4.4-meter testing pool. We are facing an issue with the confidence values and would appreciate your technical support.

Observation:

  • The depth reading is available; however, the confidence value fluctuates between 0% and 100%.

  • When the ROV approaches the bottom of the pool, the confidence becomes unstable.

  • Due to this fluctuation, the depth output is not consistently reliable.

We would like your guidance on the following:

  1. What is the recommended minimum confidence threshold for reliable operation?

  2. Is it advisable to filter and accept readings only above a certain confidence level (e.g., 80–90%)?

  3. Are there any recommended settings adjustments (gain, range, filtering parameters) for operation in a confined testing pool environment?

  4. Could this behavior be caused by multipath reflections from pool walls or bottom surface?

The sensor is mounted vertically, and basic checks such as alignment and bubble clearance have been performed.

Kindly advise on best practices to stabilize the depth output and improve confidence consistency.

12

Hi @mageshn -
My previous advice still applies.
Multi-path interference is preventing the bottom detection algorithm in the ping firmware from “locking on” with high confidence. Results with 80-90% confidence should be accurate.
Try lowering the gain in PingViewer to see if the results are improved. Setting the max range to be less than the pool depth may also help.
The minimum range is 0.3m in ideal conditions, much less in your environment.

Try the open source firmware linked previously, and if it doesn’t improve things, explore modifying it for your unique application - will you always be operating in this testing pool? If not, why the concern to get the sonar working in abnormal conditions? Performance should be radically different in real-world, open-water conditions.