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multirotor takeoff:

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instead of altering the velocity setpoint for the vehicle to takeoff
use the thrust setpoint directly. this does not depend on the tuning of
the velocity loop.
This commit is contained in:
Roman
2016-01-21 10:18:13 +01:00
parent f918b0c992
commit 7817924aef
1 changed files with 42 additions and 14 deletions
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src/modules/mc_pos_control/mc_pos_control_main.cpp
+42 -14
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@@ -250,6 +250,9 @@ private:
bool _takeoff_jumped;
float _vel_z_lp;
float _acc_z_lp;
float _takeoff_thrust_sp;
hrt_abstime _takeoff_start_time;
bool _started_takeoff;
/**
* Update our local parameter cache.
@@ -378,7 +381,10 @@ MulticopterPositionControl::MulticopterPositionControl() :
_landing_started(0),
_takeoff_jumped(false),
_vel_z_lp(0),
_acc_z_lp(0)
_acc_z_lp(0),
_takeoff_thrust_sp(0.0f),
_takeoff_start_time(0),
_started_takeoff(false)
{
memset(&_vehicle_status, 0, sizeof(_vehicle_status));
memset(&_ctrl_state, 0, sizeof(_ctrl_state));
@@ -1358,25 +1364,32 @@ MulticopterPositionControl::task_main()
if (!_control_mode.flag_control_manual_enabled && _pos_sp_triplet.current.valid
&& _pos_sp_triplet.current.type == position_setpoint_s::SETPOINT_TYPE_TAKEOFF) {
if (!_takeoff_jumped) {
/* do a quick jump (ramp vel sp up in 1/2sec) until we shoot over takeoff speed */
float accel = _vel_sp_prev(2) - _params.tko_jmpspd;
float tmp = _vel_sp_prev(2) + accel * dt * 2.0f;
_vel_sp(2) = math::max(tmp, -_params.tko_jmpspd);
if (_vel(2) < -_params.tko_speed) {
if (!_started_takeoff) {
_started_takeoff = true;
_takeoff_start_time = hrt_absolute_time();
} else if (!_takeoff_jumped) {
// ramp thrust setpoint up
if (_vel(2) > -0.5f) {
_takeoff_thrust_sp = (float)hrt_elapsed_time(&_takeoff_start_time) / 1e6f * 0.5f;
_vel_sp.zero();
_vel_prev.zero();
} else {
// copter has reached our takeoff speed. split the thrust setpoint up
// into an integral part and into a P part
thrust_int(2) = _takeoff_thrust_sp - _params.vel_p(2) * fabsf(_vel(2));
thrust_int(2) = -math::constrain(thrust_int(2), _params.thr_min, _params.thr_max);
_vel_sp(2) = -1.0f;
_vel_sp_prev(2) = -1.0f;
_takeoff_jumped = true;
reset_int_z = false;
}
} else {
/* slowly reduce forced takeoff speed to set climb rate (in 3 sec) */
float decel = _params.tko_jmpspd - _params.tko_speed;
float tmp = decel / 3.0f * dt + _vel_sp_prev(2);
_vel_sp(2) = math::min(tmp, -_params.tko_speed);
}
} else {
_takeoff_jumped = false;
_started_takeoff = false;
_takeoff_start_time = 0;
_takeoff_thrust_sp = 0.0f;
}
// limit total horizontal acceleration
@@ -1393,6 +1406,14 @@ MulticopterPositionControl::task_main()
_vel_sp(1) = vel_sp_hor(1);
}
// limit vertical acceleration
float acc_v = (_vel_sp(2) - _vel_sp_prev(2)) / dt;
if (fabsf(acc_v) > 2 * _params.acc_hor_max) {
acc_v /= fabsf(acc_v);
_vel_sp(2) = acc_v * 2 * _params.acc_hor_max * dt + _vel_sp_prev(2);
}
_vel_sp_prev = _vel_sp;
_global_vel_sp.vx = _vel_sp(0);
@@ -1450,6 +1471,13 @@ MulticopterPositionControl::task_main()
// TODO?: + _vel_sp.emult(_params.vel_ff)
math::Vector<3> thrust_sp = vel_err.emult(_params.vel_p) + _vel_err_d.emult(_params.vel_d) + thrust_int;
if (_pos_sp_triplet.current.type == position_setpoint_s::SETPOINT_TYPE_TAKEOFF
&& !_takeoff_jumped) {
// for jumped takeoffs use special thrust setpoint calculated above
thrust_sp.zero();
thrust_sp(2) = -_takeoff_thrust_sp;
}
if (!_control_mode.flag_control_velocity_enabled) {
thrust_sp(0) = 0.0f;
thrust_sp(1) = 0.0f;