Maxbotix XL-EZ0 (MB1200) Sonar Sensor Stops Working At Low Temperatures

I've started having intermittent problems with the sonar sensor on my quad.  It has performed very well up until recently. 

It is now winter (in southern Australia).  One morning, I flew in temperatures of around 5C and the MB1200 gave zero output (20 cm) for the entire flight.  I went back to the workshop to debug the problem, but it then gave correct readings and nothing I did could provoke any fault.  It also continued to operate correctly that afternoon in warmer weather. 

More recently, I flew again in around 5C conditions and again it gave zero height readings.  Leaving the system powered up, I warmed it up over a heater whereupon the sensor came to life and gave correct readings.  The Baro (green) and Sonar (red) readings are shown below:

According to the specs, the sensor is specified to work down to -40C.  So, I contacted Maxbotix who responded as follows:

We recently found an anomaly in our hardware gain that occasional would cause sensors to behave similarly to what you are describing.  This behavior only happened occasionally.  Because we believe this is the cause of the issue, we are issuing an RMA for replacement of your sensor.

I'm currently waiting for the replacement to arrive.

I'd suggest that if you're having unexplained sonar sensor malfunctions, contact Maxbotix.

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Hello Dave and the DIY community,

We saw your post and wanted to add a few remarks.  During the engineering phase, our sensors are subjected to the full temperature range of -40c to +85c to characterize performance and ensure the sensors operate.  During this original testing, the MB1200 sensors did not exhibit any issues and passed all testing as designed.  After we received a technical support request, we evaluated the behavior of the sensors over temperature and found this rare anomaly (only effecting a very small percentage of sensors) in the temperature performance. We have made a minor firmware and hardware changes to completely prevent the issue.  Since this discovery,  we have issues any replacements we believe that may be related to this temperature performance.  MaxBotix Inc is glad to help anyone requiring support.  Please feel free to send me the an email for any of your support requirements. 

Please let me know if you have any questions.

Best regards,

Scott Wielenberg
Technical Support & Sales
of MaxBotix Inc.
Phone: (218) 454-0766
Fax: (218) 454-0768

Hi Dave, did you ever get your cold temperature failure fixed of the MaxBotix ultrasonic sensors?

I bought a few and had the same issue as you described on your landing issue.

I received an RMA from Maxbotix, but I noticed no difference after the "fix"..

Thanks for your reply in advance, highly appreciated.

Pedro Cardona

Electronics Hobbyist.

I dont think anybody uses the sonars any more. IN the kit bundling wizard thing they dont offer any of the sonars as an option. Personally i dont think they work at all well, due to periodic spikes. The baro does a good enuff job.

Hi Pedro,

Since getting it back from Maxbotix, it's never really worked.  It seems to give good readings statically, but when flying, it won't work properly despite efforts with electrical noise and vibration reduction.  Now, whether that's the sensor or an "improved" version of firmware, I'm not sure.  I should sit down and wade through the logs (again) but frankly, I got tired of fiddling with it.

When it was working, it was amazing - definitely much better than Baro only.  It would terrain-follow, hover stably at low (~2m) heights and was sensitive enough to detect a wire farm fence and rise above it.



Thanks much for the info Dave.I will have to give up on it too.

Thanks mP1 for the reply. As I said to Dave, I will just give up  on the ultrasonic sensors.

Keep it and build an ardurover :)

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