mirror of https://github.com/ArduPilot/ardupilot
94 lines
3.9 KiB
C++
94 lines
3.9 KiB
C++
/*
|
|
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/>.
|
|
*/
|
|
|
|
#include <AP_Common/AP_Common.h>
|
|
#include <AP_HAL/AP_HAL.h>
|
|
#include "AP_BattMonitor.h"
|
|
#include "AP_BattMonitor_Backend.h"
|
|
|
|
/*
|
|
base class constructor.
|
|
This incorporates initialisation as well.
|
|
*/
|
|
AP_BattMonitor_Backend::AP_BattMonitor_Backend(AP_BattMonitor &mon, AP_BattMonitor::BattMonitor_State &mon_state,
|
|
AP_BattMonitor_Params ¶ms) :
|
|
_mon(mon),
|
|
_state(mon_state),
|
|
_params(params)
|
|
{
|
|
}
|
|
|
|
/// capacity_remaining_pct - returns the % battery capacity remaining (0 ~ 100)
|
|
uint8_t AP_BattMonitor_Backend::capacity_remaining_pct() const
|
|
{
|
|
float mah_remaining = _params._pack_capacity - _state.current_total_mah;
|
|
if ( _params._pack_capacity > 10 ) { // a very very small battery
|
|
return (100 * (mah_remaining) / _params._pack_capacity);
|
|
} else {
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
// update battery resistance estimate
|
|
// faster rates of change of the current and voltage readings cause faster updates to the resistance estimate
|
|
// the battery resistance is calculated by comparing the latest current and voltage readings to a low-pass filtered current and voltage
|
|
// high current steps are integrated into the resistance estimate by varying the time constant of the resistance filter
|
|
void AP_BattMonitor_Backend::update_resistance_estimate()
|
|
{
|
|
// return immediately if no current
|
|
if (!has_current() || !is_positive(_state.current_amps)) {
|
|
return;
|
|
}
|
|
|
|
// update maximum current seen since startup and protect against divide by zero
|
|
_current_max_amps = MAX(_current_max_amps, _state.current_amps);
|
|
float current_delta = _state.current_amps - _current_filt_amps;
|
|
if (is_zero(current_delta)) {
|
|
return;
|
|
}
|
|
|
|
// update reference voltage and current
|
|
if (_state.voltage > _resistance_voltage_ref) {
|
|
_resistance_voltage_ref = _state.voltage;
|
|
_resistance_current_ref = _state.current_amps;
|
|
}
|
|
|
|
// calculate time since last update
|
|
uint32_t now = AP_HAL::millis();
|
|
float loop_interval = (now - _resistance_timer_ms) / 1000.0f;
|
|
_resistance_timer_ms = now;
|
|
|
|
// estimate short-term resistance
|
|
float filt_alpha = constrain_float(loop_interval/(loop_interval + AP_BATT_MONITOR_RES_EST_TC_1), 0.0f, 0.5f);
|
|
float resistance_alpha = MIN(1, AP_BATT_MONITOR_RES_EST_TC_2*fabsf((_state.current_amps-_current_filt_amps)/_current_max_amps));
|
|
float resistance_estimate = -(_state.voltage-_voltage_filt)/current_delta;
|
|
if (is_positive(resistance_estimate)) {
|
|
_state.resistance = _state.resistance*(1-resistance_alpha) + resistance_estimate*resistance_alpha;
|
|
}
|
|
|
|
// calculate maximum resistance
|
|
if ((_resistance_voltage_ref > _state.voltage) && (_state.current_amps > _resistance_current_ref)) {
|
|
float resistance_max = (_resistance_voltage_ref - _state.voltage) / (_state.current_amps - _resistance_current_ref);
|
|
_state.resistance = MIN(_state.resistance, resistance_max);
|
|
}
|
|
|
|
// update the filtered voltage and currents
|
|
_voltage_filt = _voltage_filt*(1-filt_alpha) + _state.voltage*filt_alpha;
|
|
_current_filt_amps = _current_filt_amps*(1-filt_alpha) + _state.current_amps*filt_alpha;
|
|
|
|
// update estimated voltage without sag
|
|
_state.voltage_resting_estimate = _state.voltage + _state.current_amps * _state.resistance;
|
|
}
|