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Altimeter and auto altitude


(Etienne Demers) #21

If you tell me exactly what you need I will make it happen.


(Jacob) #22

I need to know the digital output format and whether the data is emitted by polling (how to poll?) or free running.


(Michael Woodman) #23

Has their been any progress with a auto altitude option using the micron altimeter?

Could you use the Tritech analogue out voltage ‘pin 5’ direct into the pixhawk input for a sonar input?


(Jacob) #24

There is support for analog input for rangefinders! https://www.ardusub.com/operators-manual/full-parameter-list.html#rngfndtype-rangefinder-type

This fact escaped my memory in the conversation previously.

The serial output could also be used with a small python program.


(Michael Woodman) #25

Now having the altimeter input into the pixhawk, how does this input improve the rov’s operation?


(Jacob) #26

You can hold a distance to the bottom rather than a distance to the surface. You can also see the distance to the bottom in the telemetry display.


(Kaos) #27

Any ideas on altimeters to use for this bottom tracking function?


(Jacob) #28

See the second post in this topic Altimeter and auto altitude


(Michael Woodman) #29

How much of a change to the handling of the ROV has the micron altimeter made for you? With this 6 degree altimeter sonar has it helped with terrain following and station keeping.


(Jacob) #30

I haven’t used it much. I only accomplished preliminary tests in a pool before I moved on from that project and the hardware was transferred to the owners.

We have our own altimeter coming soon that we have used more. It will allow you to do terrain following, without such a device terrain following is not possible. These types of device will not help you with station keeping, it provides no data about your position in the xy plane.


(Michael Woodman) #31

Very exciting news about your altimeter! (just between ourselves when can I place an order)
Have you ever tried to use a lidar for the terrain following function?


(Levi Cai) #32

Hello,

We are trying to write an altitude hold mode on a BlueROV2, we have already mounted a Micron echosounder (it looks just like yours) and are streaming distance readings through MAVROS. Based on the documentation here (https://www.ardusub.com/operators-manual/altimeters.html), it seems we should be able to use the altimeter instead of the depth sensor by simply sending mavlink messages via a distance range message.

We have written our own pymavlink wrapper that calls mav.distance_sensor_send(), and have also updated the RNGFNDR_TYPE to Mavlink in QGC. However, there are no indications that this behavior is working. We believe we are successfully sending the mavlink message (which we monitor by echoing the MAVROS topic /mavlink/to, and checking for message id 132, which we believe corresponds to the distance sensor message ID). We have also tried using MAVROS’ interface to publish distance readings, but again, there’s no indication that the PX4 is receiving these readings or using them. The readings are also not showing up in the QGC rangefinder listings.

Since it sounds like you’ve gotten this working already, do you have any pointers on how to properly achieve this or what we might be doing wrong/missing?

Thank you very much!


(Jacob) #33

Can you install TeamViewer and meet with me when you have everything up and running?