ardupilot/libraries/AP_Motors/AP_MotorsMulticopter.cpp

388 lines
15 KiB
C++

// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* AP_MotorsMulticopter.cpp - ArduCopter multicopter motors library
* Code by Randy Mackay and Robert Lefebvre. DIYDrones.com
*
*/
#include "AP_MotorsMulticopter.h"
#include <AP_HAL/AP_HAL.h>
extern const AP_HAL::HAL& hal;
// parameters for the motor class
const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] PROGMEM = {
// 0 was used by TB_RATIO
// 1,2,3 were used by throttle curve
// @Param: SPIN_ARMED
// @DisplayName: Motors always spin when armed
// @Description: Controls whether motors always spin when armed (must be below THR_MIN)
// @Values: 0:Do Not Spin,70:VerySlow,100:Slow,130:Medium,150:Fast
// @User: Standard
AP_GROUPINFO("SPIN_ARMED", 5, AP_MotorsMulticopter, _spin_when_armed, AP_MOTORS_SPIN_WHEN_ARMED),
// @Param: YAW_HEADROOM
// @DisplayName: Matrix Yaw Min
// @Description: Yaw control is given at least this pwm range
// @Range: 0 500
// @Units: pwm
// @User: Advanced
AP_GROUPINFO("YAW_HEADROOM", 6, AP_MotorsMulticopter, _yaw_headroom, AP_MOTORS_YAW_HEADROOM_DEFAULT),
// 7 was THR_LOW_CMP
// @Param: THST_EXPO
// @DisplayName: Thrust Curve Expo
// @Description: Motor thrust curve exponent (from 0 for linear to 1.0 for second order curve)
// @Range: 0.25 0.8
// @User: Advanced
AP_GROUPINFO("THST_EXPO", 8, AP_MotorsMulticopter, _thrust_curve_expo, AP_MOTORS_THST_EXPO_DEFAULT),
// @Param: THST_MAX
// @DisplayName: Thrust Curve Max
// @Description: Point at which the thrust saturates
// @Values: 0.9:Low, 1.0:High
// @User: Advanced
AP_GROUPINFO("THST_MAX", 9, AP_MotorsMulticopter, _thrust_curve_max, AP_MOTORS_THST_MAX_DEFAULT),
// @Param: THST_BAT_MAX
// @DisplayName: Battery voltage compensation maximum voltage
// @Description: Battery voltage compensation maximum voltage (voltage above this will have no additional scaling effect on thrust). Recommend 4.4 * cell count, 0 = Disabled
// @Range: 6 35
// @Units: Volts
// @User: Advanced
AP_GROUPINFO("THST_BAT_MAX", 10, AP_MotorsMulticopter, _batt_voltage_max, AP_MOTORS_THST_BAT_MAX_DEFAULT),
// @Param: THST_BAT_MIN
// @DisplayName: Battery voltage compensation minimum voltage
// @Description: Battery voltage compensation minimum voltage (voltage below this will have no additional scaling effect on thrust). Recommend 3.5 * cell count, 0 = Disabled
// @Range: 6 35
// @Units: Volts
// @User: Advanced
AP_GROUPINFO("THST_BAT_MIN", 11, AP_MotorsMulticopter, _batt_voltage_min, AP_MOTORS_THST_BAT_MIN_DEFAULT),
// @Param: CURR_MAX
// @DisplayName: Motor Current Max
// @Description: Maximum current over which maximum throttle is limited (0 = Disabled)
// @Range: 0 200
// @Units: Amps
// @User: Advanced
AP_GROUPINFO("CURR_MAX", 12, AP_MotorsMulticopter, _batt_current_max, AP_MOTORS_CURR_MAX_DEFAULT),
// @Param: THR_MIX_MIN
// @DisplayName: Throttle Mix Minimum
// @Description: Throttle vs attitude control prioritisation used when landing (higher values mean we prioritise attitude control over throttle)
// @Range: 0.1 0.25
// @User: Advanced
AP_GROUPINFO("THR_MIX_MIN", 13, AP_MotorsMulticopter, _thr_mix_min, AP_MOTORS_THR_MIX_MIN_DEFAULT),
// @Param: THR_MIX_MAX
// @DisplayName: Throttle Mix Maximum
// @Description: Throttle vs attitude control prioritisation used during active flight (higher values mean we prioritise attitude control over throttle)
// @Range: 0.5 0.9
// @User: Advanced
AP_GROUPINFO("THR_MIX_MAX", 14, AP_MotorsMulticopter, _thr_mix_max, AP_MOTORS_THR_MIX_MAX_DEFAULT),
AP_GROUPEND
};
// Constructor
AP_MotorsMulticopter::AP_MotorsMulticopter(uint16_t loop_rate, uint16_t speed_hz) :
AP_Motors(loop_rate, speed_hz),
_spin_when_armed_ramped(0),
_throttle_thr_mix_desired(AP_MOTORS_THR_LOW_CMP_DEFAULT),
_throttle_thr_mix(AP_MOTORS_THR_LOW_CMP_DEFAULT),
_min_throttle(AP_MOTORS_DEFAULT_MIN_THROTTLE),
_max_throttle(AP_MOTORS_DEFAULT_MAX_THROTTLE),
_hover_out(AP_MOTORS_DEFAULT_MID_THROTTLE),
_batt_voltage_resting(0.0f),
_batt_current_resting(0.0f),
_batt_resistance(0.0f),
_batt_timer(0),
_lift_max(1.0f),
_throttle_limit(1.0f)
{
AP_Param::setup_object_defaults(this, var_info);
// disable all motors by default
memset(motor_enabled, false, sizeof(motor_enabled));
// init flags
_multicopter_flags.slow_start = false;
_multicopter_flags.slow_start_low_end = true;
// setup battery voltage filtering
_batt_voltage_filt.set_cutoff_frequency(AP_MOTORS_BATT_VOLT_FILT_HZ);
_batt_voltage_filt.reset(1.0f);
};
// output - sends commands to the motors
void AP_MotorsMulticopter::output()
{
// update throttle filter
update_throttle_filter();
// update max throttle
update_max_throttle();
// update battery resistance
update_battery_resistance();
// calc filtered battery voltage and lift_max
update_lift_max_from_batt_voltage();
// move throttle_low_comp towards desired throttle low comp
update_throttle_thr_mix();
if (_flags.armed) {
if (!_flags.interlock) {
output_armed_zero_throttle();
} else if (_flags.stabilizing) {
output_armed_stabilizing();
} else {
output_armed_not_stabilizing();
}
} else {
_multicopter_flags.slow_start_low_end = true;
output_disarmed();
}
};
// update the throttle input filter
void AP_MotorsMulticopter::update_throttle_filter()
{
if (armed()) {
_throttle_filter.apply(_throttle_in, 1.0f/_loop_rate);
} else {
_throttle_filter.reset(0.0f);
}
// constrain throttle signal to 0-1000
_throttle_control_input = constrain_float(_throttle_filter.get(),0.0f,1000.0f);
}
// update_max_throttle - updates the limits on _max_throttle if necessary taking into account slow_start_throttle flag
void AP_MotorsMulticopter::update_max_throttle()
{
// ramp up minimum spin speed if necessary
if (_multicopter_flags.slow_start_low_end) {
_spin_when_armed_ramped += AP_MOTOR_SLOW_START_LOW_END_INCREMENT;
if (_spin_when_armed_ramped >= _spin_when_armed) {
_spin_when_armed_ramped = _spin_when_armed;
_multicopter_flags.slow_start_low_end = false;
}
}
// implement slow start
if (_multicopter_flags.slow_start) {
// increase slow start throttle
_max_throttle += AP_MOTOR_SLOW_START_INCREMENT;
// turn off slow start if we've reached max throttle
if (_max_throttle >= _throttle_control_input) {
_max_throttle = AP_MOTORS_DEFAULT_MAX_THROTTLE;
_multicopter_flags.slow_start = false;
}
return;
}
// current limit throttle
current_limit_max_throttle();
}
// current_limit_max_throttle - limits maximum throttle based on current
void AP_MotorsMulticopter::current_limit_max_throttle()
{
// return maximum if current limiting is disabled
if (_batt_current_max <= 0) {
_throttle_limit = 1.0f;
_max_throttle = AP_MOTORS_DEFAULT_MAX_THROTTLE;
return;
}
// remove throttle limit if throttle is at zero or disarmed
if(_throttle_control_input <= 0 || !_flags.armed) {
_throttle_limit = 1.0f;
}
// limit throttle if over current
if (_batt_current > _batt_current_max*1.25f) {
// Fast drop for extreme over current (1 second)
_throttle_limit -= 1.0f/_loop_rate;
} else if(_batt_current > _batt_current_max) {
// Slow drop for extreme over current (5 second)
_throttle_limit -= 0.2f/_loop_rate;
} else {
// Increase throttle limit (2 second)
_throttle_limit += 0.5f/_loop_rate;
}
// throttle limit drops to 20% between hover and full throttle
_throttle_limit = constrain_float(_throttle_limit, 0.2f, 1.0f);
// limit max throttle
_max_throttle = _hover_out + ((1000-_hover_out)*_throttle_limit);
}
// apply_thrust_curve_and_volt_scaling - returns throttle curve adjusted pwm value (i.e. 1000 ~ 2000)
int16_t AP_MotorsMulticopter::apply_thrust_curve_and_volt_scaling(int16_t pwm_out, int16_t pwm_min, int16_t pwm_max) const
{
// convert to 0.0 to 1.0 ratio
float throttle_ratio = ((float)(pwm_out-pwm_min))/((float)(pwm_max-pwm_min));
// apply thrust curve - domain 0.0 to 1.0, range 0.0 to 1.0
if (_thrust_curve_expo > 0.0f){
throttle_ratio = ((_thrust_curve_expo-1.0f) + safe_sqrt((1.0f-_thrust_curve_expo)*(1.0f-_thrust_curve_expo) + 4.0f*_thrust_curve_expo*_lift_max*throttle_ratio))/(2.0f*_thrust_curve_expo*_batt_voltage_filt.get());
}
// scale to maximum thrust point
throttle_ratio *= _thrust_curve_max;
// convert back to pwm range, constrain and return
return (int16_t)constrain_float(throttle_ratio*(pwm_max-pwm_min)+pwm_min, pwm_min, (pwm_max-pwm_min)*_thrust_curve_max+pwm_min);
}
// update_lift_max from battery voltage - used for voltage compensation
void AP_MotorsMulticopter::update_lift_max_from_batt_voltage()
{
// sanity check battery_voltage_min is not too small
// if disabled or misconfigured exit immediately
if((_batt_voltage_max <= 0) || (_batt_voltage_min >= _batt_voltage_max) || (_batt_voltage < 0.25f*_batt_voltage_min)) {
_batt_voltage_filt.reset(1.0f);
_lift_max = 1.0f;
return;
}
_batt_voltage_min = max(_batt_voltage_min, _batt_voltage_max * 0.6f);
// add current based voltage sag to battery voltage
float batt_voltage = _batt_voltage + _batt_current * _batt_resistance;
batt_voltage = constrain_float(batt_voltage, _batt_voltage_min, _batt_voltage_max);
// filter at 0.5 Hz
float bvf = _batt_voltage_filt.apply(batt_voltage/_batt_voltage_max, 1.0f/_loop_rate);
// calculate lift max
_lift_max = bvf*(1-_thrust_curve_expo) + _thrust_curve_expo*bvf*bvf;
}
// update_battery_resistance - calculate battery resistance when throttle is above hover_out
void AP_MotorsMulticopter::update_battery_resistance()
{
// if motors are stopped, reset resting voltage and current
if (_throttle_control_input <= 0 || !_flags.armed) {
_batt_voltage_resting = _batt_voltage;
_batt_current_resting = _batt_current;
_batt_timer = 0;
} else {
// update battery resistance when throttle is over hover throttle
if ((_batt_timer < 400) && ((_batt_current_resting*2.0f) < _batt_current)) {
if (_throttle_control_input >= _hover_out) {
// filter reaches 90% in 1/4 the test time
_batt_resistance += 0.05f*(( (_batt_voltage_resting-_batt_voltage)/(_batt_current-_batt_current_resting) ) - _batt_resistance);
_batt_timer += 1;
} else {
// initialize battery resistance to prevent change in resting voltage estimate
_batt_resistance = ((_batt_voltage_resting-_batt_voltage)/(_batt_current-_batt_current_resting));
}
}
}
}
// update_throttle_thr_mix - slew set_throttle_thr_mix to requested value
void AP_MotorsMulticopter::update_throttle_thr_mix()
{
// slew _throttle_thr_mix to _throttle_thr_mix_desired
if (_throttle_thr_mix < _throttle_thr_mix_desired) {
// increase quickly (i.e. from 0.1 to 0.9 in 0.4 seconds)
_throttle_thr_mix += min(2.0f/_loop_rate, _throttle_thr_mix_desired-_throttle_thr_mix);
} else if (_throttle_thr_mix > _throttle_thr_mix_desired) {
// reduce more slowly (from 0.9 to 0.1 in 1.6 seconds)
_throttle_thr_mix -= min(0.5f/_loop_rate, _throttle_thr_mix-_throttle_thr_mix_desired);
}
_throttle_thr_mix = constrain_float(_throttle_thr_mix, 0.1f, 1.0f);
}
// get_hover_throttle_as_pwm - converts hover throttle to pwm (i.e. range 1000 ~ 2000)
int16_t AP_MotorsMulticopter::get_hover_throttle_as_pwm() const
{
return (_throttle_radio_min + (float)(_throttle_radio_max - _throttle_radio_min) * _hover_out / 1000.0f);
}
float AP_MotorsMulticopter::get_compensation_gain() const
{
// avoid divide by zero
if (_lift_max <= 0.0f) {
return 1.0f;
}
float ret = 1.0f / _lift_max;
// air density ratio is increasing in density / decreasing in altitude
if (_air_density_ratio > 0.3f && _air_density_ratio < 1.5f) {
ret *= 1.0f / constrain_float(_air_density_ratio,0.5f,1.25f);
}
return ret;
}
float AP_MotorsMulticopter::rel_pwm_to_thr_range(float pwm) const
{
return pwm/_throttle_pwm_scalar;
}
float AP_MotorsMulticopter::thr_range_to_rel_pwm(float thr) const
{
return _throttle_pwm_scalar*thr;
}
// set_throttle_range - sets the minimum throttle that will be sent to the engines when they're not off (i.e. to prevents issues with some motors spinning and some not at very low throttle)
// also sets throttle channel minimum and maximum pwm
void AP_MotorsMulticopter::set_throttle_range(uint16_t min_throttle, int16_t radio_min, int16_t radio_max)
{
_throttle_radio_min = radio_min;
_throttle_radio_max = radio_max;
_throttle_pwm_scalar = (_throttle_radio_max - _throttle_radio_min) / 1000.0f;
_rpy_pwm_scalar = (_throttle_radio_max - (_throttle_radio_min + _min_throttle)) / 9000.0f;
_min_throttle = (float)min_throttle * _throttle_pwm_scalar;
}
// slow_start - set to true to slew motors from current speed to maximum
// Note: this must be set immediately before a step up in throttle
void AP_MotorsMulticopter::slow_start(bool true_false)
{
// set slow_start flag
_multicopter_flags.slow_start = true;
// initialise maximum throttle to current throttle
_max_throttle = constrain_int16(_throttle_control_input, 0, AP_MOTORS_DEFAULT_MAX_THROTTLE);
}
// throttle_pass_through - passes provided pwm directly to all motors - dangerous but used for initialising ESCs
// pwm value is an actual pwm value that will be output, normally in the range of 1000 ~ 2000
void AP_MotorsMulticopter::throttle_pass_through(int16_t pwm)
{
if (armed()) {
// send the pilot's input directly to each enabled motor
for (int16_t i=0; i < AP_MOTORS_MAX_NUM_MOTORS; i++) {
if (motor_enabled[i]) {
hal.rcout->write(pgm_read_byte(&_motor_to_channel_map[i]), pwm);
}
}
}
}