RE: Unable to start VL53l0x - LIDAR distance ranger sensor | CUBE orange

JulianOes · January 9, 2023, 8:29pm

@baumanta above is a question regarding obstacle prevention using a lidar. Is this something that should/could work?

baumanta · January 11, 2023, 8:26am

I was not following upstream closely recently. I remember that the collision prevention was not supported by the new position controller and there were tasks about getting rid of it. But I don’t believe that happened. So I think if you are using the old position controller it should probably be working.

sibujacob · January 11, 2023, 9:48am

Hi
What you mean by old position controller. Which px4 version are we talking here.
Why did the dev team remove such a much required safety feature for a drone.
Is there a different safety concept to replace collision avoidance feature

saengphet · January 11, 2023, 3:18pm

A year ago, I tested the collision prevention feature with MPC_POS_MODE=4 (default, Acceleration based input). It did not work, so I tried to change the param to MPC_POS_MODE=3, and it works fine as expected. However, the handling quality and overall response are lower than the default POS_MODE.

sibujacob · January 11, 2023, 10:03pm

Hi there ,

Will check this out and revert back. This is good info.

sibujacob · January 12, 2023, 10:31am

@ saengphet…Unfortunately it doesn’t work on my Px4 v12.3 version. i have a CUBE orange with QGC as ground control software. I am curious to know what is the description for MPC_POS_MODE=3

thanks

saengphet · January 14, 2023, 12:33pm

@sibujacob Have you checked the distance sensor direction by using QGC indicator (set to pitch270degree = downward)? I use the lightware LW20/C lidar with the added command “lightware_laser_i2c start -X -R 0” to make the lidar look forward. However, I forgot what firmware version I used.

sibujacob · January 14, 2023, 12:55pm

@ Saengphet my vl53l0x is having default at 25 degree . which means facing downwards. Can you tell me how to change this to forward direction from Mavlink console

saengphet · January 14, 2023, 1:10pm

@sibujacob If it already started, try to stop it first using " vl53l0x stop ", then input this command: " vl53l0x start -X -R 0 ". Please check in QGC indicator by distance sensor with ROTATION_NONE.

reference distance sensor orientation:

github.com

PX4/PX4-Autopilot/blob/main/msg/DistanceSensor.msg#L25


      
          uint8 MAV_DISTANCE_SENSOR_ULTRASOUND = 1
          uint8 MAV_DISTANCE_SENSOR_INFRARED = 2
          uint8 MAV_DISTANCE_SENSOR_RADAR = 3
          
          
float32 h_fov # Sensor horizontal field of view (rad)
          float32 v_fov # Sensor vertical field of view (rad)
          float32[4] q # Quaterion sensor orientation with respect to the vehicle body frame to specify the orientation ROTATION_CUSTOM
          
          
uint8 orientation		# Direction the sensor faces from MAV_SENSOR_ORIENTATION enum
          
          
uint8 ROTATION_YAW_0		= 0 # MAV_SENSOR_ROTATION_NONE
          uint8 ROTATION_YAW_45		= 1 # MAV_SENSOR_ROTATION_YAW_45
          uint8 ROTATION_YAW_90		= 2 # MAV_SENSOR_ROTATION_YAW_90
          uint8 ROTATION_YAW_135		= 3 # MAV_SENSOR_ROTATION_YAW_135
          uint8 ROTATION_YAW_180		= 4 # MAV_SENSOR_ROTATION_YAW_180
          uint8 ROTATION_YAW_225		= 5 # MAV_SENSOR_ROTATION_YAW_225
          uint8 ROTATION_YAW_270		= 6 # MAV_SENSOR_ROTATION_YAW_270
          uint8 ROTATION_YAW_315		= 7 # MAV_SENSOR_ROTATION_YAW_315
          
          
uint8 ROTATION_FORWARD_FACING	= 0 # MAV_SENSOR_ROTATION_NONE
          uint8 ROTATION_RIGHT_FACING	= 2 # MAV_SENSOR_ROTATION_YAW_90

sibujacob · January 14, 2023, 2:24pm

Just wanted to know whether we require GPS lock for this distance sensor to work ? It is night in my location . if GPS is not required, i could try it inside.

The distance sensor reading after your feedback on QGC indicator

I tested in prearm mode It measures from 0m up to 0.5 to 0.56 m and then jumps straight to 8.2 m !! Why does it do that ? I still haven’t tested the collision detection in flight due to night time here

saengphet · January 14, 2023, 3:50pm

@sibujacob The position (either global via GPS or local via VIO/SLAM) is required by the collision avoidance system. To function, the drone must be in position hold mode. Concerning the distance sensor error, I’m not sure what the underlying cause is. I recommend that you validate the distance by pointing the sensor at a flat wall and comparing it to the true distance value (and the spec sheet too). I have never used the VL53I0x before.

sibujacob · January 14, 2023, 4:15pm

thank you for your valuable feedback. I will check this and post the results

sibujacob · January 15, 2023, 6:51am

@saengphet … After doing a test as per your recommendation, the drone doesn’t do any sort of collision prevention !
What I also saw during flight ( Position mode ) while close to the wall , the sensor doesn’t do any ranging either. But in pre arm on ground, i see the sensor ranging as I described earlier. i had placed the sensor at 1 meter minimum distance . The VL53l0x has a range from
0 m to 2 m.
Strangely the distance sensor graph show up on the flight review !!