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AC_AttControl_Heli: Add LPF filter to Rate Feedforward terms

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This commit is contained in:
Robert Lefebvre 2014-05-10 10:17:32 -04:00 committed by Randy Mackay
parent 8eb557d1e0
commit 26be7aed97
2 changed files with 24 additions and 4 deletions
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17
libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp
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@ -139,8 +139,8 @@ void AC_AttitudeControl_Heli::rate_bf_to_motor_roll_pitch(float rate_roll_target
}
}
roll_ff = ((AC_HELI_PID&)_pid_rate_roll).get_ff(rate_roll_target_cds);
pitch_ff = ((AC_HELI_PID&)_pid_rate_pitch).get_ff(rate_pitch_target_cds);
roll_ff = roll_feedforward_filter.apply(((AC_HELI_PID&)_pid_rate_roll).get_ff(rate_roll_target_cds));
pitch_ff = pitch_feedforward_filter.apply(((AC_HELI_PID&)_pid_rate_pitch).get_ff(rate_pitch_target_cds));
// add feed forward and final output
roll_out = roll_pd + roll_i + roll_ff;
@ -271,8 +271,8 @@ float AC_AttitudeControl_Heli::rate_bf_to_motor_yaw(float rate_target_cds)
i = ((AC_HELI_PID&)_pid_rate_yaw).get_leaky_i(rate_error, _dt, AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE); // If motor is not running use leaky I-term to avoid excessive build-up
}
}
ff = ((AC_HELI_PID&)_pid_rate_yaw).get_ff(rate_target_cds);
ff = yaw_feedforward_filter.apply(((AC_HELI_PID&)_pid_rate_yaw).get_ff(rate_target_cds));
// add feed forward
yaw_out = pd + i + ff;
@ -301,3 +301,12 @@ int16_t AC_AttitudeControl_Heli::get_angle_boost(int16_t throttle_pwm)
_angle_boost = 0;
return throttle_pwm;
}
// update_feedforward_filter_rate - Sets LPF cutoff frequency
void AC_AttitudeControl_Heli::update_feedforward_filter_rates(float time_step)
{
pitch_feedforward_filter.set_cutoff_frequency(time_step, AC_ATTITUDE_HELI_RATE_FF_FILTER);
roll_feedforward_filter.set_cutoff_frequency(time_step, AC_ATTITUDE_HELI_RATE_FF_FILTER);
yaw_feedforward_filter.set_cutoff_frequency(time_step, AC_ATTITUDE_HELI_RATE_FF_FILTER);
}

11
libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.h
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@ -8,11 +8,13 @@
#include <AC_AttitudeControl.h>
#include <AC_HELI_PID.h>
#include <FILTER.h>
#define AC_ATTITUDE_HELI_ROLL_FF 0.0f
#define AC_ATTITUDE_HELI_PITCH_FF 0.0f
#define AC_ATTITUDE_HELI_YAW_FF 0.0f
#define AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE 0.02f
#define AC_ATTITUDE_HELI_RATE_FF_FILTER 5.0f
class AC_AttitudeControl_Heli : public AC_AttitudeControl {
public:
@ -36,6 +38,8 @@ public:
// use_leaky_i - controls whether we use leaky i term for body-frame to motor output stage
void use_leaky_i(bool leaky_i) { _flags_heli.leaky_i = leaky_i; }
void update_feedforward_filter_rates(float time_step);
// user settable parameters
static const struct AP_Param::GroupInfo var_info[];
@ -64,6 +68,13 @@ private:
// get_angle_boost - calculate total body frame throttle required to produce the given earth frame throttle
virtual int16_t get_angle_boost(int16_t throttle_pwm);
// LPF filters to act on Rate Feedforward terms to linearize output.
// Due to complicated aerodynamic effects, feedforwards acting too fast can lead
// to jerks on rate change requests.
LowPassFilterInt32 pitch_feedforward_filter;
LowPassFilterInt32 roll_feedforward_filter;
LowPassFilterInt32 yaw_feedforward_filter;
};