Can I use Bendy Ruler with 3 radar rangefinder?

Hello, I’m planning to build a Arducopter crop sprayer with fully autonomous obstacle avoidance by using Bendy Ruler, as copter 4.2.0 has improved this function.

My question is, can I use one radar foward, one left, one right (plus one radar for terrain following)?

Why I want to do this? I want to use horizontal bendy ruler, so, when foward sensor find the obstacle, the copter will find a path by going to left or right, thats why I might need 2 extra sensors pointing left and right, so the copter can see in that direction.


Yes, that could work. I think you’ll need to setup the individual lidar including the RNGFNDx_ORIENT parameters and then set PRX_TYPE = 4 (RangeFinder).

The only thing is that AP doesn’t create a 3D map, instead it just uses the sensor input directly. This can lead to false positives when the lidar sees the ground as it leans over OR on the other hand not seeing obstacles because the lidar passes just to the left or right of skinny obstacles.

I guess I’m saying that it works OK but in practice I’m still not sure it is very robust.

Hi @rmackay9 your are right if use point lidar ( laser based lidar) but @GiovaneM saying about the radar which has the more FOV in both horizontal and vertical direction?.

I might be wrong, but there are no lightweight beam forming Radar commercially available at the moment.
There is some experiments with this one , but that is still a WIP:
Finally Texas Instruments mm wave radar (3D Radar) IWR6843AOPEVM is working as proximity sensor

Other issue deals with multiple proximity sensors, there is no way (for the moment) to merge all sensor at the Flight Controller level. You will need to work with a Companion Computer level to control , merge and genereate the required signals to the FC.


A single proximity sensor setup (e.g. PRX_TYPE = 4) will blend the input from multiple single beam lidar if the RNGFNDx_ORIENT values are set correctly.

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You are right, I meant multiple large apperture sensor devices like the scanning lidars and 180 degs radars

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Yes and No at the moment.

Last month I finished a similar project with 6 benewake tf mini plus lidars all around- works just fine in normal flight. However in auto modes there is an issue where the copter will make a full stop at every way point. I don’t think the issue has yet been resolved but someone will correct me if I’m wrong.

Expect this behaviour in auto mode with OA on.

[Rover: enabling bendy ruler leads to a 1sec delay at each waypoint · Issue #20140 · ArduPilot/ardupilot · GitHub]

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