mirror of https://github.com/ArduPilot/ardupilot
249 lines
10 KiB
C++
249 lines
10 KiB
C++
/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <AP_Common/AP_Common.h>
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#include <AP_HAL/AP_HAL.h>
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#include "AP_BattMonitor.h"
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#include "AP_BattMonitor_Backend.h"
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/*
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base class constructor.
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This incorporates initialisation as well.
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*/
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AP_BattMonitor_Backend::AP_BattMonitor_Backend(AP_BattMonitor &mon, AP_BattMonitor::BattMonitor_State &mon_state,
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AP_BattMonitor_Params ¶ms) :
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_mon(mon),
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_state(mon_state),
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_params(params)
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{
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}
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/// capacity_remaining_pct - returns true if the battery % is available and writes to the percentage argument
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bool AP_BattMonitor_Backend::capacity_remaining_pct(uint8_t &percentage) const
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{
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// we consider anything under 10 mAh as being an invalid capacity and so will be our measurement of remaining capacity
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if ( _params._pack_capacity <= 10) {
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return false;
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}
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const float mah_remaining = _params._pack_capacity - _state.consumed_mah;
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percentage = constrain_float(100 * mah_remaining / _params._pack_capacity, 0, UINT8_MAX);
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return true;
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}
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// update battery resistance estimate
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// faster rates of change of the current and voltage readings cause faster updates to the resistance estimate
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// the battery resistance is calculated by comparing the latest current and voltage readings to a low-pass filtered current and voltage
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// high current steps are integrated into the resistance estimate by varying the time constant of the resistance filter
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void AP_BattMonitor_Backend::update_resistance_estimate()
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{
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// return immediately if no current
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if (!has_current() || !is_positive(_state.current_amps)) {
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return;
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}
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// update maximum current seen since startup and protect against divide by zero
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_current_max_amps = MAX(_current_max_amps, _state.current_amps);
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float current_delta = _state.current_amps - _current_filt_amps;
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if (is_zero(current_delta)) {
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return;
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}
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// update reference voltage and current
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if (_state.voltage > _resistance_voltage_ref) {
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_resistance_voltage_ref = _state.voltage;
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_resistance_current_ref = _state.current_amps;
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}
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// calculate time since last update
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uint32_t now = AP_HAL::millis();
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float loop_interval = (now - _resistance_timer_ms) / 1000.0f;
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_resistance_timer_ms = now;
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// estimate short-term resistance
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float filt_alpha = constrain_float(loop_interval/(loop_interval + AP_BATT_MONITOR_RES_EST_TC_1), 0.0f, 0.5f);
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float resistance_alpha = MIN(1, AP_BATT_MONITOR_RES_EST_TC_2*fabsf((_state.current_amps-_current_filt_amps)/_current_max_amps));
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float resistance_estimate = -(_state.voltage-_voltage_filt)/current_delta;
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if (is_positive(resistance_estimate)) {
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_state.resistance = _state.resistance*(1-resistance_alpha) + resistance_estimate*resistance_alpha;
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}
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// calculate maximum resistance
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if ((_resistance_voltage_ref > _state.voltage) && (_state.current_amps > _resistance_current_ref)) {
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float resistance_max = (_resistance_voltage_ref - _state.voltage) / (_state.current_amps - _resistance_current_ref);
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_state.resistance = MIN(_state.resistance, resistance_max);
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}
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// update the filtered voltage and currents
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_voltage_filt = _voltage_filt*(1-filt_alpha) + _state.voltage*filt_alpha;
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_current_filt_amps = _current_filt_amps*(1-filt_alpha) + _state.current_amps*filt_alpha;
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// update estimated voltage without sag
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_state.voltage_resting_estimate = _state.voltage + _state.current_amps * _state.resistance;
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}
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float AP_BattMonitor_Backend::voltage_resting_estimate() const
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{
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// resting voltage should always be greater than or equal to the raw voltage
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return MAX(_state.voltage, _state.voltage_resting_estimate);
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}
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AP_BattMonitor::Failsafe AP_BattMonitor_Backend::update_failsafes(void)
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{
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const uint32_t now = AP_HAL::millis();
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bool low_voltage, low_capacity, critical_voltage, critical_capacity;
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check_failsafe_types(low_voltage, low_capacity, critical_voltage, critical_capacity);
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if (critical_voltage) {
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// this is the first time our voltage has dropped below minimum so start timer
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if (_state.critical_voltage_start_ms == 0) {
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_state.critical_voltage_start_ms = now;
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} else if (_params._low_voltage_timeout > 0 &&
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now - _state.critical_voltage_start_ms > uint32_t(_params._low_voltage_timeout)*1000U) {
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return AP_BattMonitor::Failsafe::Critical;
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}
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} else {
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// acceptable voltage so reset timer
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_state.critical_voltage_start_ms = 0;
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}
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if (critical_capacity) {
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return AP_BattMonitor::Failsafe::Critical;
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}
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if (low_voltage) {
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// this is the first time our voltage has dropped below minimum so start timer
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if (_state.low_voltage_start_ms == 0) {
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_state.low_voltage_start_ms = now;
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} else if (_params._low_voltage_timeout > 0 &&
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now - _state.low_voltage_start_ms > uint32_t(_params._low_voltage_timeout)*1000U) {
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return AP_BattMonitor::Failsafe::Low;
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}
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} else {
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// acceptable voltage so reset timer
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_state.low_voltage_start_ms = 0;
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}
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if (low_capacity) {
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return AP_BattMonitor::Failsafe::Low;
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}
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// if we've gotten this far then battery is ok
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return AP_BattMonitor::Failsafe::None;
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}
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static bool update_check(size_t buflen, char *buffer, bool failed, const char *message)
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{
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if (failed) {
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strncpy(buffer, message, buflen);
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return false;
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}
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return true;
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}
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bool AP_BattMonitor_Backend::arming_checks(char * buffer, size_t buflen) const
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{
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bool low_voltage, low_capacity, critical_voltage, critical_capacity;
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check_failsafe_types(low_voltage, low_capacity, critical_voltage, critical_capacity);
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bool below_arming_voltage = is_positive(_params._arming_minimum_voltage) &&
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(_state.voltage < _params._arming_minimum_voltage);
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bool below_arming_capacity = (_params._arming_minimum_capacity > 0) &&
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((_params._pack_capacity - _state.consumed_mah) < _params._arming_minimum_capacity);
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bool fs_capacity_inversion = is_positive(_params._critical_capacity) &&
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is_positive(_params._low_capacity) &&
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(_params._low_capacity < _params._critical_capacity);
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bool fs_voltage_inversion = is_positive(_params._critical_voltage) &&
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is_positive(_params._low_voltage) &&
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(_params._low_voltage < _params._critical_voltage);
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bool result = update_check(buflen, buffer, below_arming_voltage, "below minimum arming voltage");
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result = result && update_check(buflen, buffer, below_arming_capacity, "below minimum arming capacity");
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result = result && update_check(buflen, buffer, low_voltage, "low voltage failsafe");
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result = result && update_check(buflen, buffer, low_capacity, "low capacity failsafe");
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result = result && update_check(buflen, buffer, critical_voltage, "critical voltage failsafe");
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result = result && update_check(buflen, buffer, critical_capacity, "critical capacity failsafe");
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result = result && update_check(buflen, buffer, fs_capacity_inversion, "capacity failsafe critical > low");
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result = result && update_check(buflen, buffer, fs_voltage_inversion, "voltage failsafe critical > low");
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return result;
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}
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void AP_BattMonitor_Backend::check_failsafe_types(bool &low_voltage, bool &low_capacity, bool &critical_voltage, bool &critical_capacity) const
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{
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// use voltage or sag compensated voltage
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float voltage_used;
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switch (_params.failsafe_voltage_source()) {
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case AP_BattMonitor_Params::BattMonitor_LowVoltageSource_Raw:
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default:
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voltage_used = _state.voltage;
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break;
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case AP_BattMonitor_Params::BattMonitor_LowVoltageSource_SagCompensated:
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voltage_used = voltage_resting_estimate();
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break;
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}
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// check critical battery levels
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if ((voltage_used > 0) && (_params._critical_voltage > 0) && (voltage_used < _params._critical_voltage)) {
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critical_voltage = true;
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} else {
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critical_voltage = false;
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}
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// check capacity failsafe if current monitoring is enabled
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if (has_current() && (_params._critical_capacity > 0) &&
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((_params._pack_capacity - _state.consumed_mah) < _params._critical_capacity)) {
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critical_capacity = true;
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} else {
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critical_capacity = false;
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}
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if ((voltage_used > 0) && (_params._low_voltage > 0) && (voltage_used < _params._low_voltage)) {
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low_voltage = true;
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} else {
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low_voltage = false;
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}
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// check capacity if current monitoring is enabled
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if (has_current() && (_params._low_capacity > 0) &&
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((_params._pack_capacity - _state.consumed_mah) < _params._low_capacity)) {
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low_capacity = true;
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} else {
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low_capacity = false;
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}
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}
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/*
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default implementation for reset_remaining(). This sets consumed_wh
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and consumed_mah based on the given percentage. Use percentage=100
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for a full battery
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*/
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bool AP_BattMonitor_Backend::reset_remaining(float percentage)
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{
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percentage = constrain_float(percentage, 0, 100);
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const float used_proportion = (100.0f - percentage) * 0.01f;
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_state.consumed_mah = used_proportion * _params._pack_capacity;
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// without knowing the history we can't do consumed_wh
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// accurately. Best estimate is based on current voltage. This
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// will be good when resetting the battery to a value close to
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// full charge
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_state.consumed_wh = _state.consumed_mah * 0.001f * _state.voltage;
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// reset failsafe state for this backend
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_state.failsafe = update_failsafes();
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return true;
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}
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