MR 72 serial RADAR configuration for proximity

ArduCopter Copter 4.4
1

Hi I planning to use two MR 72 radar one at front and one at back side of the drone for proximity object avoidance.

I have configured both MR 72 Radar using PRX1 and PRX 2 parameters accordingly on two different serial ports. Both sensor working ok but issue is I couldn’t configure which one is front and which is back . AP also doesn’t know it’s orientation hence both the radar results in only front direction of the drone even back radar detect obstacles at back.

I know that RNGFNDx_Orientation parameter can set orientation with respect to vehicle orientation. But this radar doesn’t support those parameters currently.

@rishabsingh3003 @rmackay9

2

We don’t support MR72 serial version officially. We do have CAN version support in 4.5.
Regardless, the parameter you are looking for PRX1_YAW_CORR and PRX2_YAW_CORR is Complete Parameter List — Copter documentation

Note Proximity sensors like MR72 are configured using PRX_. RNGFND_ will have no effect…

3

Thank you your quick response @rishabsingh3003
I have tried this parameter on both the radars and seems no effect.

4

What PRX_TYPE backend do you use? As I said, we don’t officially support the MR72-Serial
Are you on a standard ArduPilot release, or do you have some custom changes to support MR72-Serial?

5

I used PRX_TYPE - 6 ( tower EVO 360) .

I don’t use any custom AP version it’s genaral and official version of AC 4.4.4

6

The driver does not support setting YAW_CORR. My guess is that the original sensor (EVO 360) is a 360-degree lidar, and does not need yaw correction. Unfortunately, that means there is no way from ArduPilot side that you can get a different orientation (without a custom firmware).

7

@rishabsingh3003 we have significantly customised AP’s version 4.1 for our use case. However, we want to use MR72 for obstacle avoidance in AP4.1. Here are a few options i can think of:

  1. Copy paste drivers for MR72 and hope everything works (I have no clue about complexity of this)
  2. Interface sensor with CC, and send obstacle data using OBSTACLE_DISTANCE mavlink messages at 10 Hz. (I am concerned about MAVLINK’s bandwidth and delay)
8

It might be difficult copy-pasting the CAN driver that we do have because it involves some changes down at the AP_CANManger level (to be able to support multiple CAN MR72’s) and it isn’t just local to AP_Proximity. If you can, I would recommend upgrading to 4.5 stable release.
(2) should be okay, depending on how congested your existing link is

9

Understood. Thanks so much for the insights Rishabh. When you suggest congestion on existing mavlink link, is there any metric to measure/gauge it?
Also, our company uses drones to spray pesticides in field (AUTO modes). For our use case, bendy ruler doesnot work (as per my understanding), because it avoids an obstacle and doesnot merge on to the existing path between waypoints, causing spraying on a path that may have already been sprayed!
Am I missing anything here?
Is there a way to setup parameters such that Bendy ruler/other avoidance options merges with the main path?

10

Hey @kalai1219 , how did you configured the MR72 radar to work with ardupilot using serial?

I am using the same radar, I am able to get it to work with the NSM_77 tool but I have no Idea on how to configure it for ardupilot.

Could you please list the steps?

11

Do you mean that MR72 CAN version supported in firmware 4.5 ?
I can’t find configuration for that in wiki.
Should I use custom firmware for it?

12

No custom firmware is required for MR72 CAN in 4.5 Rover/Copter. We natively support it.
Documentation is coming to our wiki, sorry for the delay! You could also ask NanoRadar for documentation.