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AP_Motors: move thrust linerization to its own class

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Iampete1 2023-01-31 01:54:00 +00:00 committed by Andrew Tridgell
parent 5d68f44694
commit ab4777de14
13 changed files with 225 additions and 179 deletions
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6
libraries/AP_Motors/AP_MotorsCoax.cpp
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@ -91,8 +91,8 @@ void AP_MotorsCoax::output_to_motors()
for (uint8_t i = 0; i < NUM_ACTUATORS; i++) {
rc_write_angle(AP_MOTORS_MOT_1 + i, _actuator_out[i] * AP_MOTORS_COAX_SERVO_INPUT_RANGE);
}
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_5], thrust_to_actuator(_thrust_yt_ccw));
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_6], thrust_to_actuator(_thrust_yt_cw));
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_5], thr_lin.thrust_to_actuator(_thrust_yt_ccw));
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_6], thr_lin.thrust_to_actuator(_thrust_yt_cw));
rc_write(AP_MOTORS_MOT_5, output_to_pwm(_actuator[AP_MOTORS_MOT_5]));
rc_write(AP_MOTORS_MOT_6, output_to_pwm(_actuator[AP_MOTORS_MOT_6]));
break;
@ -129,7 +129,7 @@ void AP_MotorsCoax::output_armed_stabilizing()
float actuator_allowed = 0.0f; // amount of yaw we can fit in
// apply voltage and air pressure compensation
const float compensation_gain = get_compensation_gain();
const float compensation_gain = thr_lin.get_compensation_gain();
roll_thrust = (_roll_in + _roll_in_ff) * compensation_gain;
pitch_thrust = (_pitch_in + _pitch_in_ff) * compensation_gain;
yaw_thrust = (_yaw_in + _yaw_in_ff) * compensation_gain;

6
libraries/AP_Motors/AP_MotorsMatrix.cpp
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@ -168,7 +168,7 @@ void AP_MotorsMatrix::output_to_motors()
// set motor output based on thrust requests
for (i = 0; i < AP_MOTORS_MAX_NUM_MOTORS; i++) {
if (motor_enabled[i]) {
set_actuator_with_slew(_actuator[i], thrust_to_actuator(_thrust_rpyt_out[i]));
set_actuator_with_slew(_actuator[i], thr_lin.thrust_to_actuator(_thrust_rpyt_out[i]));
}
}
break;
@ -213,7 +213,7 @@ float AP_MotorsMatrix::boost_ratio(float boost_value, float normal_value) const
void AP_MotorsMatrix::output_armed_stabilizing()
{
// apply voltage and air pressure compensation
const float compensation_gain = get_compensation_gain(); // compensation for battery voltage and altitude
const float compensation_gain = thr_lin.get_compensation_gain(); // compensation for battery voltage and altitude
// pitch thrust input value, +/- 1.0
const float roll_thrust = (_roll_in + _roll_in_ff) * compensation_gain;
@ -454,7 +454,7 @@ void AP_MotorsMatrix::check_for_failed_motor(float throttle_thrust_best_plus_adj
}
// check to see if thrust boost is using more throttle than _throttle_thrust_max
if ((_throttle_thrust_max * get_compensation_gain() > throttle_thrust_best_plus_adj) && (rpyt_high < 0.9f) && _thrust_balanced) {
if ((_throttle_thrust_max * thr_lin.get_compensation_gain() > throttle_thrust_best_plus_adj) && (rpyt_high < 0.9f) && _thrust_balanced) {
_thrust_boost = false;
}
}

8
libraries/AP_Motors/AP_MotorsMatrix_6DoF_Scripting.cpp
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@ -46,17 +46,17 @@ void AP_MotorsMatrix_6DoF_Scripting::output_to_motors()
if (_reversible[i]) {
// revesible motor can provide both positive and negative thrust, +- spin max, spin min does not apply
if (is_positive(_thrust_rpyt_out[i])) {
_actuator[i] = apply_thrust_curve_and_volt_scaling(_thrust_rpyt_out[i]) * _spin_max;
_actuator[i] = thr_lin.apply_thrust_curve_and_volt_scaling(_thrust_rpyt_out[i]) * thr_lin.get_spin_max();
} else if (is_negative(_thrust_rpyt_out[i])) {
_actuator[i] = -apply_thrust_curve_and_volt_scaling(-_thrust_rpyt_out[i]) * _spin_max;
_actuator[i] = -thr_lin.apply_thrust_curve_and_volt_scaling(-_thrust_rpyt_out[i]) * thr_lin.get_spin_max();
} else {
_actuator[i] = 0.0f;
}
} else {
// motor can only provide trust in a single direction, spin min to spin max as 'normal' copter
_actuator[i] = thrust_to_actuator(_thrust_rpyt_out[i]);
_actuator[i] = thr_lin.thrust_to_actuator(_thrust_rpyt_out[i]);
}
}
}
@ -85,7 +85,7 @@ void AP_MotorsMatrix_6DoF_Scripting::output_armed_stabilizing()
// note that the throttle, forwards and right inputs are not in bodyframe, they are in the frame of the 'normal' 4DoF copter were pretending to be
// apply voltage and air pressure compensation
const float compensation_gain = get_compensation_gain(); // compensation for battery voltage and altitude
const float compensation_gain = thr_lin.get_compensation_gain(); // compensation for battery voltage and altitude
roll_thrust = (_roll_in + _roll_in_ff) * compensation_gain;
pitch_thrust = (_pitch_in + _pitch_in_ff) * compensation_gain;
yaw_thrust = (_yaw_in + _yaw_in_ff) * compensation_gain;

137
libraries/AP_Motors/AP_MotorsMulticopter.cpp
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@ -49,14 +49,14 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
// @Description: Motor thrust curve exponent (0.0 for linear to 1.0 for second order curve)
// @Range: -1.0 1.0
// @User: Advanced
AP_GROUPINFO("THST_EXPO", 8, AP_MotorsMulticopter, _thrust_curve_expo, AP_MOTORS_THST_EXPO_DEFAULT),
AP_GROUPINFO("THST_EXPO", 8, AP_MotorsMulticopter, thr_lin.curve_expo, AP_MOTORS_THST_EXPO_DEFAULT),
// @Param: SPIN_MAX
// @DisplayName: Motor Spin maximum
// @Description: Point at which the thrust saturates expressed as a number from 0 to 1 in the entire output range
// @Values: 0.9:Low, 0.95:Default, 1.0:High
// @User: Advanced
AP_GROUPINFO("SPIN_MAX", 9, AP_MotorsMulticopter, _spin_max, AP_MOTORS_SPIN_MAX_DEFAULT),
AP_GROUPINFO("SPIN_MAX", 9, AP_MotorsMulticopter, thr_lin.spin_max, AP_MOTORS_SPIN_MAX_DEFAULT),
// @Param: BAT_VOLT_MAX
// @DisplayName: Battery voltage compensation maximum voltage
@ -64,7 +64,7 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
// @Range: 6 53
// @Units: V
// @User: Advanced
AP_GROUPINFO("BAT_VOLT_MAX", 10, AP_MotorsMulticopter, _batt_voltage_max, AP_MOTORS_BAT_VOLT_MAX_DEFAULT),
AP_GROUPINFO("BAT_VOLT_MAX", 10, AP_MotorsMulticopter, thr_lin.batt_voltage_max, AP_MOTORS_BAT_VOLT_MAX_DEFAULT),
// @Param: BAT_VOLT_MIN
// @DisplayName: Battery voltage compensation minimum voltage
@ -72,7 +72,7 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
// @Range: 6 42
// @Units: V
// @User: Advanced
AP_GROUPINFO("BAT_VOLT_MIN", 11, AP_MotorsMulticopter, _batt_voltage_min, AP_MOTORS_BAT_VOLT_MIN_DEFAULT),
AP_GROUPINFO("BAT_VOLT_MIN", 11, AP_MotorsMulticopter, thr_lin.batt_voltage_min, AP_MOTORS_BAT_VOLT_MIN_DEFAULT),
// @Param: BAT_CURR_MAX
// @DisplayName: Motor Current Max
@ -113,7 +113,7 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
// @Description: Point at which the thrust starts expressed as a number from 0 to 1 in the entire output range. Should be higher than MOT_SPIN_ARM.
// @Values: 0.0:Low, 0.15:Default, 0.25:High
// @User: Advanced
AP_GROUPINFO("SPIN_MIN", 18, AP_MotorsMulticopter, _spin_min, AP_MOTORS_SPIN_MIN_DEFAULT),
AP_GROUPINFO("SPIN_MIN", 18, AP_MotorsMulticopter, thr_lin.spin_min, AP_MOTORS_SPIN_MIN_DEFAULT),
// @Param: SPIN_ARM
// @DisplayName: Motor Spin armed
@ -186,7 +186,7 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
// @Description: Which battery monitor should be used for doing compensation
// @Values: 0:First battery, 1:Second battery
// @User: Advanced
AP_GROUPINFO("BAT_IDX", 39, AP_MotorsMulticopter, _batt_idx, 0),
AP_GROUPINFO("BAT_IDX", 39, AP_MotorsMulticopter, thr_lin.batt_idx, 0),
// @Param: SLEW_UP_TIME
// @DisplayName: Output slew time for increasing throttle
@ -221,15 +221,9 @@ const AP_Param::GroupInfo AP_MotorsMulticopter::var_info[] = {
// Constructor
AP_MotorsMulticopter::AP_MotorsMulticopter(uint16_t speed_hz) :
AP_Motors(speed_hz),
_lift_max(1.0f),
_throttle_limit(1.0f)
{
AP_Param::setup_object_defaults(this, var_info);
// 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
@ -239,7 +233,7 @@ void AP_MotorsMulticopter::output()
update_throttle_filter();
// calc filtered battery voltage and lift_max
update_lift_max_from_batt_voltage();
thr_lin.update_lift_max_from_batt_voltage();
// run spool logic
output_logic();
@ -337,16 +331,17 @@ float AP_MotorsMulticopter::get_current_limit_max_throttle()
{
AP_BattMonitor &battery = AP::battery();
const uint8_t batt_idx = thr_lin.get_battery_index();
float _batt_current;
if (_batt_current_max <= 0 || // return maximum if current limiting is disabled
!armed() || // remove throttle limit if disarmed
!battery.current_amps(_batt_current, _batt_idx)) { // no current monitoring is available
!battery.current_amps(_batt_current, batt_idx)) { // no current monitoring is available
_throttle_limit = 1.0f;
return 1.0f;
}
float _batt_resistance = battery.get_resistance(_batt_idx);
float _batt_resistance = battery.get_resistance(batt_idx);
if (is_zero(_batt_resistance)) {
_throttle_limit = 1.0f;
@ -354,7 +349,7 @@ float AP_MotorsMulticopter::get_current_limit_max_throttle()
}
// calculate the maximum current to prevent voltage sag below _batt_voltage_min
float batt_current_max = MIN(_batt_current_max, _batt_current + (battery.voltage(_batt_idx) - _batt_voltage_min) / _batt_resistance);
float batt_current_max = MIN(_batt_current_max, _batt_current + (battery.voltage(batt_idx) - thr_lin.get_battery_min_voltage()) / _batt_resistance);
float batt_current_ratio = _batt_current / batt_current_max;
@ -367,67 +362,6 @@ float AP_MotorsMulticopter::get_current_limit_max_throttle()
return get_throttle_hover() + ((1.0 - get_throttle_hover()) * _throttle_limit);
}
// apply_thrust_curve_and_volt_scaling - returns throttle in the range 0 ~ 1
float AP_MotorsMulticopter::apply_thrust_curve_and_volt_scaling(float thrust) const
{
float battery_scale = 1.0;
if (is_positive(_batt_voltage_filt.get())) {
battery_scale = 1.0 / _batt_voltage_filt.get();
}
// apply thrust curve - domain -1.0 to 1.0, range -1.0 to 1.0
float thrust_curve_expo = constrain_float(_thrust_curve_expo, -1.0f, 1.0f);
if (is_zero(thrust_curve_expo)) {
// zero expo means linear, avoid floating point exception for small values
return _lift_max * thrust * battery_scale;
}
float 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 * thrust)) / (2.0f * thrust_curve_expo);
return constrain_float(throttle_ratio * battery_scale, 0.0f, 1.0f);
}
// inverse of above, tested with AP_Motors/examples/expo_inverse_test
// used to calculate equivelent motor throttle level to direct ouput, used in tailsitter transtions
float AP_MotorsMulticopter::remove_thrust_curve_and_volt_scaling(float throttle) const
{
float battery_scale = 1.0;
if (is_positive(_batt_voltage_filt.get())) {
battery_scale = 1.0 / _batt_voltage_filt.get();
}
// apply thrust curve - domain -1.0 to 1.0, range -1.0 to 1.0
float thrust_curve_expo = constrain_float(_thrust_curve_expo, -1.0f, 1.0f);
if (is_zero(thrust_curve_expo)) {
// zero expo means linear, avoid floating point exception for small values
return throttle / (_lift_max * battery_scale);
}
float thrust = ((throttle / battery_scale) * (2.0f * thrust_curve_expo)) - (thrust_curve_expo - 1.0f);
thrust = (thrust * thrust) - ((1.0f - thrust_curve_expo) * (1.0f - thrust_curve_expo));
thrust /= 4.0f * thrust_curve_expo * _lift_max;
return constrain_float(thrust, 0.0f, 1.0f);
}
// 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
float _batt_voltage_resting_estimate = AP::battery().voltage_resting_estimate(_batt_idx);
if ((_batt_voltage_max <= 0) || (_batt_voltage_min >= _batt_voltage_max) || (_batt_voltage_resting_estimate < 0.25f * _batt_voltage_min)) {
_batt_voltage_filt.reset(1.0f);
_lift_max = 1.0f;
return;
}
_batt_voltage_min.set(MAX(_batt_voltage_min, _batt_voltage_max * 0.6f));
// contrain resting voltage estimate (resting voltage is actual voltage with sag removed based on current draw and resistance)
_batt_voltage_resting_estimate = constrain_float(_batt_voltage_resting_estimate, _batt_voltage_min, _batt_voltage_max);
// filter at 0.5 Hz
float batt_voltage_filt = _batt_voltage_filt.apply(_batt_voltage_resting_estimate / _batt_voltage_max, _dt);
// calculate lift max
float thrust_curve_expo = constrain_float(_thrust_curve_expo, -1.0f, 1.0f);
_lift_max = batt_voltage_filt * (1 - thrust_curve_expo) + thrust_curve_expo * batt_voltage_filt * batt_voltage_filt;
}
// 10hz logging of voltage scaling and max trust
void AP_MotorsMulticopter::Log_Write()
@ -435,8 +369,8 @@ void AP_MotorsMulticopter::Log_Write()
const struct log_MotBatt pkt_mot {
LOG_PACKET_HEADER_INIT(LOG_MOTBATT_MSG),
time_us : AP_HAL::micros64(),
lift_max : _lift_max,
bat_volt : _batt_voltage_filt.get(),
lift_max : thr_lin.get_lift_max(),
bat_volt : thr_lin.batt_voltage_filt.get(),
th_limit : _throttle_limit,
th_average_max : _throttle_avg_max,
th_out : _throttle_out,
@ -445,24 +379,6 @@ void AP_MotorsMulticopter::Log_Write()
AP::logger().WriteBlock(&pkt_mot, sizeof(pkt_mot));
}
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;
#if AP_MOTORS_DENSITY_COMP == 1
// 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);
}
#endif
return ret;
}
// convert actuator output (0~1) range to pwm range
int16_t AP_MotorsMulticopter::output_to_pwm(float actuator)
{
@ -482,21 +398,6 @@ int16_t AP_MotorsMulticopter::output_to_pwm(float actuator)
return pwm_output;
}
// converts desired thrust to linearized actuator output in a range of 0~1
float AP_MotorsMulticopter::thrust_to_actuator(float thrust_in) const
{
thrust_in = constrain_float(thrust_in, 0.0f, 1.0f);
return _spin_min + (_spin_max - _spin_min) * apply_thrust_curve_and_volt_scaling(thrust_in);
}
// inverse of above, tested with AP_Motors/examples/expo_inverse_test
// used to calculate equivelent motor throttle level to direct ouput, used in tailsitter transtions
float AP_MotorsMulticopter::actuator_to_thrust(float actuator) const
{
actuator = (actuator - _spin_min) / (_spin_max - _spin_min);
return constrain_float(remove_thrust_curve_and_volt_scaling(actuator), 0.0f, 1.0f);
}
// adds slew rate limiting to actuator output
void AP_MotorsMulticopter::set_actuator_with_slew(float& actuator_output, float input)
{
@ -530,7 +431,7 @@ void AP_MotorsMulticopter::set_actuator_with_slew(float& actuator_output, float
// gradually increase actuator output to spin_min
float AP_MotorsMulticopter::actuator_spin_up_to_ground_idle() const
{
return constrain_float(_spin_up_ratio, 0.0f, 1.0f) * _spin_min;
return constrain_float(_spin_up_ratio, 0.0f, 1.0f) * thr_lin.get_spin_min();
}
// parameter checks for MOT_PWM_MIN/MAX, returns true if parameters are valid
@ -655,8 +556,8 @@ void AP_MotorsMulticopter::output_logic()
case DesiredSpoolState::GROUND_IDLE:
float spin_up_armed_ratio = 0.0f;
if (_spin_min > 0.0f) {
spin_up_armed_ratio = _spin_arm / _spin_min;
if (thr_lin.get_spin_min() > 0.0f) {
spin_up_armed_ratio = _spin_arm / thr_lin.get_spin_min();
}
_spin_up_ratio += constrain_float(spin_up_armed_ratio - _spin_up_ratio, -spool_step, spool_step);
break;
@ -858,11 +759,11 @@ bool AP_MotorsMulticopter::arming_checks(size_t buflen, char *buffer) const
}
// Check param config
if (_spin_min > 0.3) {
hal.util->snprintf(buffer, buflen, "%sSPIN_MIN too high %.2f > 0.3", AP_MOTORS_PARAM_PREFIX, _spin_min.get());
if (thr_lin.get_spin_min() > 0.3) {
hal.util->snprintf(buffer, buflen, "%sSPIN_MIN too high %.2f > 0.3", AP_MOTORS_PARAM_PREFIX, thr_lin.get_spin_min());
return false;
}
if (_spin_arm > _spin_min) {
if (_spin_arm > thr_lin.get_spin_min()) {
hal.util->snprintf(buffer, buflen, "%sSPIN_ARM > %sSPIN_MIN", AP_MOTORS_PARAM_PREFIX, AP_MOTORS_PARAM_PREFIX);
return false;
}

34
libraries/AP_Motors/AP_MotorsMulticopter.h
View File

@ -3,10 +3,7 @@
#pragma once
#include "AP_Motors_Class.h"
#ifndef AP_MOTORS_DENSITY_COMP
#define AP_MOTORS_DENSITY_COMP 1
#endif
#include "AP_Motors_Thrust_Linearization.h"
#define AP_MOTORS_YAW_HEADROOM_DEFAULT 200
#define AP_MOTORS_THST_EXPO_DEFAULT 0.65f // set to 0 for linear and 1 for second order approximation
@ -21,7 +18,6 @@
#define AP_MOTORS_BAT_VOLT_MIN_DEFAULT 0.0f // voltage limiting min default (voltage dropping below this level will have no effect)
#define AP_MOTORS_BAT_CURR_MAX_DEFAULT 0.0f // current limiting max default
#define AP_MOTORS_BAT_CURR_TC_DEFAULT 5.0f // Time constant used to limit the maximum current
#define AP_MOTORS_BATT_VOLT_FILT_HZ 0.5f // battery voltage filtered at 0.5hz
#define AP_MOTORS_SLEW_TIME_DEFAULT 0.0f // slew rate limit for thrust output
#define AP_MOTORS_SAFE_TIME_DEFAULT 1.0f // Time for the esc when transitioning between zero pwm to minimum
@ -77,12 +73,6 @@ public:
// parameter check for MOT_PWM_MIN/MAX, returns true if parameters are valid
bool check_mot_pwm_params() const;
// converts desired thrust to linearized actuator output in a range of 0~1
float thrust_to_actuator(float thrust_in) const;
// inverse of above
float actuator_to_thrust(float actuator) const;
// set thrust compensation callback
FUNCTOR_TYPEDEF(thrust_compensation_fn_t, void, float *, uint8_t);
void set_thrust_compensation_callback(thrust_compensation_fn_t callback) {
@ -109,6 +99,9 @@ public:
float get_throttle_avg_max() const;
int16_t get_yaw_headroom() const;
// Thrust Linearization handling
Thrust_Linearization thr_lin {*this};
// var_info for holding Parameter information
static const struct AP_Param::GroupInfo var_info[];
@ -126,17 +119,6 @@ protected:
// return current_limit as a number from 0 ~ 1 in the range throttle_min to throttle_max
virtual float get_current_limit_max_throttle();
// apply_thrust_curve_and_volt_scaling - returns throttle in the range 0 ~ 1
float apply_thrust_curve_and_volt_scaling(float thrust) const;
// inverse of above
float remove_thrust_curve_and_volt_scaling(float throttle) const;
// update_lift_max_from_batt_voltage - used for voltage compensation
void update_lift_max_from_batt_voltage();
// return gain scheduling gain based on voltage and air density
float get_compensation_gain() const;
// convert actuator output (0~1) range to pwm range
int16_t output_to_pwm(float _actuator_output);
@ -170,18 +152,12 @@ protected:
// parameters
AP_Int16 _yaw_headroom; // yaw control is given at least this pwm range
AP_Float _thrust_curve_expo; // curve used to linearize pwm to thrust conversion. set to 0 for linear and 1 for second order approximation
AP_Float _slew_up_time; // throttle increase slew limitting
AP_Float _slew_dn_time; // throttle decrease slew limitting
AP_Float _safe_time; // Time for the esc when transitioning between zero pwm to minimum
AP_Float _spin_min; // throttle out ratio which produces the minimum thrust. (i.e. 0 ~ 1 ) of the full throttle range
AP_Float _spin_max; // throttle out ratio which produces the maximum thrust. (i.e. 0 ~ 1 ) of the full throttle range
AP_Float _spin_arm; // throttle out ratio which produces the armed spin rate. (i.e. 0 ~ 1 ) of the full throttle range
AP_Float _batt_voltage_max; // maximum voltage used to scale lift
AP_Float _batt_voltage_min; // minimum voltage used to scale lift
AP_Float _batt_current_max; // current over which maximum throttle is limited
AP_Float _batt_current_time_constant; // Time constant used to limit the maximum current
AP_Int8 _batt_idx; // battery index used for compensation
AP_Int16 _pwm_min; // minimum PWM value that will ever be output to the motors (if 0, vehicle's throttle input channel's min pwm used)
AP_Int16 _pwm_max; // maximum PWM value that will ever be output to the motors (if 0, vehicle's throttle input channel's max pwm used)
AP_Float _throttle_hover; // estimated throttle required to hover throttle in the range 0 ~ 1
@ -204,8 +180,6 @@ protected:
float _spin_up_ratio; // throttle percentage (0 ~ 1) between zero and throttle_min
// battery voltage, current and air pressure compensation variables
LowPassFilterFloat _batt_voltage_filt; // filtered battery voltage expressed as a percentage (0 ~ 1.0) of batt_voltage_max
float _lift_max; // maximum lift ratio from battery voltage
float _throttle_limit; // ratio of throttle limit between hover and maximum
float _throttle_thrust_max; // the maximum allowed throttle thrust 0.0 to 1.0 in the range throttle_min to throttle_max
float _disarm_safe_timer; // Timer for the esc when transitioning between zero pwm to minimum

6
libraries/AP_Motors/AP_MotorsSingle.cpp
View File

@ -94,8 +94,8 @@ void AP_MotorsSingle::output_to_motors()
for (uint8_t i = 0; i < NUM_ACTUATORS; i++) {
rc_write_angle(AP_MOTORS_MOT_1 + i, _actuator_out[i] * AP_MOTORS_SINGLE_SERVO_INPUT_RANGE);
}
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_5], thrust_to_actuator(_thrust_out));
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_6], thrust_to_actuator(_thrust_out));
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_5], thr_lin.thrust_to_actuator(_thrust_out));
set_actuator_with_slew(_actuator[AP_MOTORS_MOT_6], thr_lin.thrust_to_actuator(_thrust_out));
rc_write(AP_MOTORS_MOT_5, output_to_pwm(_actuator[AP_MOTORS_MOT_5]));
rc_write(AP_MOTORS_MOT_6, output_to_pwm(_actuator[AP_MOTORS_MOT_6]));
break;
@ -134,7 +134,7 @@ void AP_MotorsSingle::output_armed_stabilizing()
float actuator_max = 0.0f; // maximum actuator value
// apply voltage and air pressure compensation
const float compensation_gain = get_compensation_gain();
const float compensation_gain = thr_lin.get_compensation_gain();
roll_thrust = (_roll_in + _roll_in_ff) * compensation_gain;
pitch_thrust = (_pitch_in + _pitch_in_ff) * compensation_gain;
yaw_thrust = (_yaw_in + _yaw_in_ff) * compensation_gain;

8
libraries/AP_Motors/AP_MotorsTailsitter.cpp
View File

@ -95,9 +95,9 @@ void AP_MotorsTailsitter::output_to_motors()
case SpoolState::SPOOLING_UP:
case SpoolState::THROTTLE_UNLIMITED:
case SpoolState::SPOOLING_DOWN:
set_actuator_with_slew(_actuator[0], thrust_to_actuator(_thrust_left));
set_actuator_with_slew(_actuator[1], thrust_to_actuator(_thrust_right));
set_actuator_with_slew(_actuator[2], thrust_to_actuator(_throttle));
set_actuator_with_slew(_actuator[0], thr_lin.thrust_to_actuator(_thrust_left));
set_actuator_with_slew(_actuator[1], thr_lin.thrust_to_actuator(_thrust_right));
set_actuator_with_slew(_actuator[2], thr_lin.thrust_to_actuator(_throttle));
break;
}
@ -143,7 +143,7 @@ void AP_MotorsTailsitter::output_armed_stabilizing()
float thr_adj = 0.0f; // the difference between the pilot's desired throttle and throttle_thrust_best_rpy
// apply voltage and air pressure compensation
const float compensation_gain = get_compensation_gain();
const float compensation_gain = thr_lin.get_compensation_gain();
roll_thrust = (_roll_in + _roll_in_ff) * compensation_gain;
pitch_thrust = _pitch_in + _pitch_in_ff;
yaw_thrust = _yaw_in + _yaw_in_ff;

8
libraries/AP_Motors/AP_MotorsTri.cpp
View File

@ -109,9 +109,9 @@ void AP_MotorsTri::output_to_motors()
case SpoolState::THROTTLE_UNLIMITED:
case SpoolState::SPOOLING_DOWN:
// set motor output based on thrust requests
set_actuator_with_slew(_actuator[1], thrust_to_actuator(_thrust_right));
set_actuator_with_slew(_actuator[2], thrust_to_actuator(_thrust_left));
set_actuator_with_slew(_actuator[4], thrust_to_actuator(_thrust_rear));
set_actuator_with_slew(_actuator[1], thr_lin.thrust_to_actuator(_thrust_right));
set_actuator_with_slew(_actuator[2], thr_lin.thrust_to_actuator(_thrust_left));
set_actuator_with_slew(_actuator[4], thr_lin.thrust_to_actuator(_thrust_rear));
rc_write(AP_MOTORS_MOT_1, output_to_pwm(_actuator[1]));
rc_write(AP_MOTORS_MOT_2, output_to_pwm(_actuator[2]));
rc_write(AP_MOTORS_MOT_4, output_to_pwm(_actuator[4]));
@ -157,7 +157,7 @@ void AP_MotorsTri::output_armed_stabilizing()
_yaw_servo_angle_max_deg.set(constrain_float(_yaw_servo_angle_max_deg, AP_MOTORS_TRI_SERVO_RANGE_DEG_MIN, AP_MOTORS_TRI_SERVO_RANGE_DEG_MAX));
// apply voltage and air pressure compensation
const float compensation_gain = get_compensation_gain();
const float compensation_gain = thr_lin.get_compensation_gain();
roll_thrust = (_roll_in + _roll_in_ff) * compensation_gain;
pitch_thrust = (_pitch_in + _pitch_in_ff) * compensation_gain;
yaw_thrust = (_yaw_in + _yaw_in_ff) * compensation_gain * sinf(radians(_yaw_servo_angle_max_deg)); // we scale this so a thrust request of 1.0f will ask for full servo deflection at full rear throttle

3
libraries/AP_Motors/AP_Motors_Class.cpp
View File

@ -33,8 +33,7 @@ AP_Motors::AP_Motors(uint16_t speed_hz) :
_throttle_slew(),
_throttle_slew_filter(),
_spool_desired(DesiredSpoolState::SHUT_DOWN),
_spool_state(SpoolState::SHUT_DOWN),
_air_density_ratio(1.0f)
_spool_state(SpoolState::SHUT_DOWN)
{
_singleton = this;

6
libraries/AP_Motors/AP_Motors_Class.h
View File

@ -188,9 +188,6 @@ public:
// get_spool_state - get current spool state
enum SpoolState get_spool_state(void) const { return _spool_state; }
// set_density_ratio - sets air density as a proportion of sea level density
void set_air_density_ratio(float ratio) { _air_density_ratio = ratio; }
// set_dt / get_dt - dt is the time since the last time the motor mixers were updated
// _dt should be set based on the time of the last IMU read used by these controllers
// the motor mixers should run on each loop to ensure normal operation
@ -324,9 +321,6 @@ protected:
DesiredSpoolState _spool_desired; // desired spool state
SpoolState _spool_state; // current spool mode
// air pressure compensation variables
float _air_density_ratio; // air density / sea level density - decreases in altitude
// mask of what channels need fast output
uint32_t _motor_fast_mask;

118
libraries/AP_Motors/AP_Motors_Thrust_Linearization.cpp Normal file
View File

@ -0,0 +1,118 @@
#include "AP_Motors_Thrust_Linearization.h"
#include "AP_Motors_Class.h"
#include <AP_BattMonitor/AP_BattMonitor.h>
#include <AP_Baro/AP_Baro.h>
#define AP_MOTORS_BATT_VOLT_FILT_HZ 0.5 // battery voltage filtered at 0.5hz
#ifndef AP_MOTORS_DENSITY_COMP
#define AP_MOTORS_DENSITY_COMP 1
#endif
Thrust_Linearization::Thrust_Linearization(AP_Motors& _motors) :
motors(_motors),
lift_max(1.0)
{
// setup battery voltage filtering
batt_voltage_filt.set_cutoff_frequency(AP_MOTORS_BATT_VOLT_FILT_HZ);
batt_voltage_filt.reset(1.0);
}
// converts desired thrust to linearized actuator output in a range of 0~1
float Thrust_Linearization::thrust_to_actuator(float thrust_in) const
{
thrust_in = constrain_float(thrust_in, 0.0, 1.0);
return spin_min + (spin_max - spin_min) * apply_thrust_curve_and_volt_scaling(thrust_in);
}
// inverse of above, tested with AP_Motors/examples/expo_inverse_test
// used to calculate equivelent motor throttle level to direct ouput, used in tailsitter transtions
float Thrust_Linearization::actuator_to_thrust(float actuator) const
{
actuator = (actuator - spin_min) / (spin_max - spin_min);
return constrain_float(remove_thrust_curve_and_volt_scaling(actuator), 0.0, 1.0);
}
// apply_thrust_curve_and_volt_scaling - returns throttle in the range 0 ~ 1
float Thrust_Linearization::apply_thrust_curve_and_volt_scaling(float thrust) const
{
float battery_scale = 1.0;
if (is_positive(batt_voltage_filt.get())) {
battery_scale = 1.0 / batt_voltage_filt.get();
}
// apply thrust curve - domain -1.0 to 1.0, range -1.0 to 1.0
float thrust_curve_expo = constrain_float(curve_expo, -1.0, 1.0);
if (is_zero(thrust_curve_expo)) {
// zero expo means linear, avoid floating point exception for small values
return lift_max * thrust * battery_scale;
}
float throttle_ratio = ((thrust_curve_expo - 1.0) + safe_sqrt((1.0 - thrust_curve_expo) * (1.0 - thrust_curve_expo) + 4.0 * thrust_curve_expo * lift_max * thrust)) / (2.0 * thrust_curve_expo);
return constrain_float(throttle_ratio * battery_scale, 0.0, 1.0);
}
// inverse of above, tested with AP_Motors/examples/expo_inverse_test
// used to calculate equivelent motor throttle level to direct ouput, used in tailsitter transtions
float Thrust_Linearization::remove_thrust_curve_and_volt_scaling(float throttle) const
{
float battery_scale = 1.0;
if (is_positive(batt_voltage_filt.get())) {
battery_scale = 1.0 / batt_voltage_filt.get();
}
// apply thrust curve - domain -1.0 to 1.0, range -1.0 to 1.0
float thrust_curve_expo = constrain_float(curve_expo, -1.0, 1.0);
if (is_zero(thrust_curve_expo)) {
// zero expo means linear, avoid floating point exception for small values
return throttle / (lift_max * battery_scale);
}
float thrust = ((throttle / battery_scale) * (2.0 * thrust_curve_expo)) - (thrust_curve_expo - 1.0);
thrust = (thrust * thrust) - ((1.0 - thrust_curve_expo) * (1.0 - thrust_curve_expo));
thrust /= 4.0 * thrust_curve_expo * lift_max;
return constrain_float(thrust, 0.0, 1.0);
}
// update_lift_max from battery voltage - used for voltage compensation
void Thrust_Linearization::update_lift_max_from_batt_voltage()
{
// sanity check battery_voltage_min is not too small
// if disabled or misconfigured exit immediately
float _batt_voltage_resting_estimate = AP::battery().voltage_resting_estimate(batt_idx);
if ((batt_voltage_max <= 0) || (batt_voltage_min >= batt_voltage_max) || (_batt_voltage_resting_estimate < 0.25 * batt_voltage_min)) {
batt_voltage_filt.reset(1.0);
lift_max = 1.0;
return;
}
batt_voltage_min.set(MAX(batt_voltage_min, batt_voltage_max * 0.6));
// contrain resting voltage estimate (resting voltage is actual voltage with sag removed based on current draw and resistance)
_batt_voltage_resting_estimate = constrain_float(_batt_voltage_resting_estimate, batt_voltage_min, batt_voltage_max);
// filter at 0.5 Hz
float batt_voltage_flittered = batt_voltage_filt.apply(_batt_voltage_resting_estimate / batt_voltage_max, motors.get_dt());
// calculate lift max
float thrust_curve_expo = constrain_float(curve_expo, -1.0, 1.0);
lift_max = batt_voltage_flittered * (1 - thrust_curve_expo) + thrust_curve_expo * batt_voltage_flittered * batt_voltage_flittered;
}
// return gain scheduling gain based on voltage and air density
float Thrust_Linearization::get_compensation_gain() const
{
// avoid divide by zero
if (get_lift_max() <= 0.0) {
return 1.0;
}
float ret = 1.0 / get_lift_max();
#if AP_MOTORS_DENSITY_COMP == 1
// air density ratio is increasing in density / decreasing in altitude
const float air_density_ratio = AP::baro().get_air_density_ratio();
if (air_density_ratio > 0.3 && air_density_ratio < 1.5) {
ret *= 1.0 / constrain_float(air_density_ratio, 0.5, 1.25);
}
#endif
return ret;
}

60
libraries/AP_Motors/AP_Motors_Thrust_Linearization.h Normal file
View File

@ -0,0 +1,60 @@
#pragma once
#include <AP_Param/AP_Param.h>
#include <Filter/LowPassFilter.h>
class AP_Motors;
class Thrust_Linearization {
friend class AP_MotorsMulticopter;
friend class AP_MotorsMulticopter_test;
public:
Thrust_Linearization(AP_Motors& _motors);
// Apply_thrust_curve_and_volt_scaling - returns throttle in the range 0 ~ 1
float apply_thrust_curve_and_volt_scaling(float thrust) const;
// Inverse of above
float remove_thrust_curve_and_volt_scaling(float throttle) const;
// Converts desired thrust to linearized actuator output in a range of 0~1
float thrust_to_actuator(float thrust_in) const;
// Inverse of above
float actuator_to_thrust(float actuator) const;
// Update_lift_max_from_batt_voltage - used for voltage compensation
void update_lift_max_from_batt_voltage();
// return gain scheduling gain based on voltage and air density
float get_compensation_gain() const;
// Get spin min parameter value
float get_spin_min() const { return spin_min.get(); }
// Get spin max parameter value
float get_spin_max() const { return spin_max.get(); }
// Get spin max parameter value
int8_t get_battery_index() const { return batt_idx.get(); }
// Get min battery voltage
float get_battery_min_voltage() const { return batt_voltage_min.get(); }
// Get lift max
float get_lift_max() const { return lift_max; }
protected:
AP_Float curve_expo; // curve used to linearize pwm to thrust conversion. set to 0 for linear and 1 for second order approximation
AP_Float spin_min; // throttle out ratio which produces the minimum thrust. (i.e. 0 ~ 1 ) of the full throttle range
AP_Float spin_max; // throttle out ratio which produces the maximum thrust. (i.e. 0 ~ 1 ) of the full throttle range
AP_Int8 batt_idx; // battery index used for compensation
AP_Float batt_voltage_max; // maximum voltage used to scale lift
AP_Float batt_voltage_min; // minimum voltage used to scale lift
private:
float lift_max; // maximum lift ratio from battery voltage
float throttle_limit; // ratio of throttle limit between hover and maximum
LowPassFilterFloat batt_voltage_filt; // filtered battery voltage expressed as a percentage (0 ~ 1.0) of batt_voltage_max
AP_Motors& motors;
};

4
libraries/AP_Motors/examples/expo_inverse_test/expo_inverse_test.cpp
View File

@ -44,7 +44,7 @@ public:
void output_to_motors() override {};
// helper function to allow setting of expo
void set_expo(float v) { _thrust_curve_expo.set(v); }
void set_expo(float v) { thr_lin.curve_expo.set(v); }
};
@ -74,7 +74,7 @@ void setup(void)
float throttle = 0.0;
while (throttle < 1.0+throttle_step*0.5) {
const float throttle_out = motors.actuator_to_thrust(motors.thrust_to_actuator(throttle));
const float throttle_out = motors.thr_lin.actuator_to_thrust(motors.thr_lin.thrust_to_actuator(throttle));
const double diff = fabsf(throttle_out - throttle);
if (diff > max_diff) {
max_diff_throttle = throttle;