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85 lines
2.4 KiB
85 lines
2.4 KiB
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*- |
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// Code by Jon Challinger |
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// |
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// This library is free software; you can redistribute it and / or |
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// modify it under the terms of the GNU Lesser General Public |
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// License as published by the Free Software Foundation; either |
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// version 2.1 of the License, or (at your option) any later version. |
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#include <AP_Math.h> |
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#include <AP_HAL.h> |
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#include "AP_YawController.h" |
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extern const AP_HAL::HAL& hal; |
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const AP_Param::GroupInfo AP_YawController::var_info[] PROGMEM = { |
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AP_GROUPINFO("P", 0, AP_YawController, _kp, 0), |
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AP_GROUPINFO("I", 1, AP_YawController, _ki, 0), |
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AP_GROUPINFO("IMAX", 2, AP_YawController, _imax, 0), |
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AP_GROUPEND |
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}; |
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// Low pass filter cut frequency for derivative calculation. |
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// FCUT macro computes a frequency cut based on an acceptable delay. |
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#define FCUT(d) (1 / ( 2 * 3.14f * (d) ) ) |
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const float AP_YawController::_fCut = FCUT(0.5f); |
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int32_t AP_YawController::get_servo_out(float scaler, bool stick_movement) |
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{ |
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uint32_t tnow = hal.scheduler->millis(); |
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uint32_t dt = tnow - _last_t; |
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if (_last_t == 0 || dt > 1000) { |
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dt = 0; |
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} |
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_last_t = tnow; |
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if(_ins == NULL) { // can't control without a reference |
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return 0; |
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} |
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float delta_time = (float) dt / 1000.0f; |
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if(stick_movement) { |
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if(!_stick_movement) { |
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_stick_movement_begin = tnow; |
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} else { |
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if(_stick_movement_begin < tnow-333) { |
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_freeze_start_time = tnow; |
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} |
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} |
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} |
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_stick_movement = stick_movement; |
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Vector3f accels = _ins->get_accel(); |
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// I didn't pull 512 out of a hat - it is a (very) loose approximation of |
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// 100*ToDeg(asinf(-accels.y/9.81f)) |
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// which, with a P of 1.0, would mean that your rudder angle would be |
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// equal to your roll angle when |
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// the plane is still. Thus we have an (approximate) unit to go by. |
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float error = 512 * -accels.y; |
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// strongly filter the error |
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float RC = 1/(2*PI*_fCut); |
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error = _last_error + |
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(delta_time / (RC + delta_time)) * (error - _last_error); |
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_last_error = error; |
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// integrator |
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if(_freeze_start_time < (tnow - 2000)) { |
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if ((fabsf(_ki) > 0) && (dt > 0)) { |
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_integrator += (error * _ki) * scaler * delta_time; |
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if (_integrator < -_imax) _integrator = -_imax; |
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else if (_integrator > _imax) _integrator = _imax; |
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} |
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} else { |
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_integrator = 0; |
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} |
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return (error * _kp * scaler) + _integrator; |
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} |
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void AP_YawController::reset_I() |
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{ |
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_integrator = 0; |
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}
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