Waypoint Acceleration Limits

quadcpp31 · February 8, 2021, 5:34pm

Hello,
I want to finish the waypoint mission as fast as possible. The first thing I’m looking for is to disable 5 m/s2 limit in WPNAV_ACCEL parameter. Or can I just set WPNAV_ACCEL like 15 m/s2 or something? It says it has a range of 50-500 cm/s2 in the full parameters list but can I just pass the 500 limit and set it like 1500?

iampete · February 8, 2021, 5:49pm

You can set it to whatever you like, the hard limit in the code is 1G ie 980 cm/s2.

quadcpp31 · February 8, 2021, 6:01pm

Hi,

Now I see.
In AC_PosControl.h:
#define POSCONTROL_ACCEL_XY_MAX 980.0f

Will changing this work? I’m just asking, 9.8m/s2 is already enough but I want to know

Btw, this acceleration value is valid in braking too, right? Or do I need to change LOIT_BRK_ACCEL or something?

Thanks.

iampete · February 8, 2021, 6:20pm

Sort of, there are also angle limits and such that will stop you going past 45 deg.

Yeah its both acceleration and braking.

quadcpp31 · February 8, 2021, 6:23pm

Do you mean PSC_ANGLE_MAX and ANGLE_MAX or is there something else I should see in the code?

iampete · February 8, 2021, 6:36pm

Both, there are hard limits in the code at 45 also a soft limit based on remaining throttle. You get much past 55 and the altitude controller starts to break.

quadcpp31 · February 8, 2021, 6:54pm

What about WPNAV_SPEED? Wiki says 20 m/s max, can I just write 30 m/s in parameters list or is there a limitation in the code?

I’m familiar with buiding the code btw that won’t be a problem.

quadcpp31 · February 13, 2021, 4:29pm

Hi Pete, I couldn’t see any bank angle limitations in the code for copter (4.1.0-dev). Can you tell me how is the limit applied?

iampete · February 13, 2021, 4:57pm

github.com

ArduPilot/ardupilot/blob/1b74058842954e7257c6475f21042be2102fe768/libraries/AC_AttitudeControl/AC_AttitudeControl.cpp#L845


            _accel_yaw_max.load();
        }
    } else {
        _accel_roll_max = 0.0f;
        _accel_pitch_max = 0.0f;
        _accel_yaw_max = 0.0f;
    }
}


// Return tilt angle limit for pilot input that prioritises altitude hold over lean angle
float AC_AttitudeControl::get_althold_lean_angle_max() const
{
    // convert to centi-degrees for public interface
    return MAX(ToDeg(_althold_lean_angle_max), AC_ATTITUDE_CONTROL_ANGLE_LIMIT_MIN) * 100.0f;
}


// Return roll rate step size in centidegrees/s that results in maximum output after 4 time steps
float AC_AttitudeControl::max_rate_step_bf_roll()
{
    float alpha = MIN(get_rate_roll_pid().get_filt_E_alpha(), get_rate_roll_pid().get_filt_D_alpha());
    float alpha_remaining = 1 - alpha;

quadcpp31 · February 13, 2021, 6:21pm

So I can increase that limit by %50 by changing 100.0f to 150.f at the end of line 848, is that right? Just asking for reference.

iampete · February 13, 2021, 7:07pm

sure, obviously there will be a true vehicle limitation there somewhere if you increase it past that bad things will start to happen.