Doesn't stop drone at Avoid Margin distance

kalai1219 · September 13, 2023, 2:40pm

I have configured Proximity sensor for obstacle avoidance function and configured
Avoid enable = 3
Avoid_behave= 1 ( stop)
Avoid_margin = 15 meter( kept high because of flying speed also High)

I was tried to do the Avoid function in loiter Mode at 10m/s speed and drone expected to stop at 15m before the obstacle, but due to high speed the drone could not able to stop at Avoid_ Margin distance and it come very close to the obstacle almost 1meter distance.

If i fly the drone on low speed it can able to stop at desired point some how .

What parameter will make the smoother stop at 15m when flying speed at 10m/s.

How to deaccelarate smoothly?

amilcarlucas · September 13, 2023, 3:03pm

Change the LOIT_BRK_* parameters

kalai1219 · September 13, 2023, 3:29pm

More aggressive stop in loiter mode?

amilcarlucas · September 13, 2023, 7:18pm

Yeap. And a better PID tuning will also allow you to stop faster.

PrateekJain · July 25, 2024, 11:52am

Hi, @kalai1219 we have also noticed that in auto flights the drone does not stop if the speed is 10m/s. It stops if is it 8m/s.
Did you understand the reason for this?
@Shubham_Saboo

andyp1per · July 25, 2024, 3:54pm

The acceleration is not considered

github.com

ArduPilot/ardupilot/blob/f849187333b02a898b7cb9e07117eada751f2045/libraries/AC_WPNav/AC_Loiter.cpp#L272


      
              // Apply EKF limit to desired velocity -  this limit is calculated by the EKF and adjusted as required to ensure certain sensor limits are respected (eg optical flow sensing)
              float horizSpdDem = desired_vel.length();
              if (horizSpdDem > gnd_speed_limit_cms) {
                  desired_vel.x = desired_vel.x * gnd_speed_limit_cms / horizSpdDem;
                  desired_vel.y = desired_vel.y * gnd_speed_limit_cms / horizSpdDem;
              }
          
          #if AP_AVOIDANCE_ENABLED && !APM_BUILD_TYPE(APM_BUILD_ArduPlane)
              if (avoidance_on) {
                  // Limit the velocity to prevent fence violations
                  // TODO: We need to also limit the _desired_accel
                  AC_Avoid *_avoid = AP::ac_avoid();
                  if (_avoid != nullptr) {
                      Vector3f avoidance_vel_3d{desired_vel.x, desired_vel.y, 0.0f};
                      _avoid->adjust_velocity(avoidance_vel_3d, _pos_control.get_pos_xy_p().kP(), _accel_cmss, _pos_control.get_pos_z_p().kP(), _pos_control.get_max_accel_z_cmss(), dt);
                      desired_vel = Vector2f{avoidance_vel_3d.x, avoidance_vel_3d.y};
                  }
              }
          #endif // !APM_BUILD_ArduPlane
          
              // get loiters desired velocity from the position controller where it is being stored.