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battery: compute remaining flight time

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This commit is contained in:
Matthias Grob 2021-06-30 16:29:29 +02:00
parent 54f2e91775
commit 73287e8e8c
2 changed files with 33 additions and 3 deletions
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30
src/lib/battery/battery.cpp
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@ -54,6 +54,7 @@ Battery::Battery(int index, ModuleParams *parent, const int sample_interval_us)
const float expected_filter_dt = static_cast<float>(sample_interval_us) / 1_s;
_voltage_filter_v.setParameters(expected_filter_dt, 1.f);
_current_filter_a.setParameters(expected_filter_dt, .5f);
_current_average_filter_a.setParameters(expected_filter_dt, 25.f);
_throttle_filter.setParameters(expected_filter_dt, 1.f);
if (index > 9 || index < 1) {
@ -127,10 +128,11 @@ void Battery::updateBatteryStatus(const hrt_abstime &timestamp, float voltage_v,
battery_status.voltage_filtered_v = _voltage_filter_v.getState();
battery_status.current_a = current_a;
battery_status.current_filtered_a = _current_filter_a.getState();
battery_status.current_average_a = -1.f; // support will follow
battery_status.current_average_a = _current_average_filter_a.getState();
battery_status.discharged_mah = _discharged_mah;
battery_status.remaining = _state_of_charge;
battery_status.scale = _scale;
battery_status.time_remaining_s = computeRemainingTime(current_a);
battery_status.temperature = NAN;
// Publish at least one cell such that the total voltage gets into MAVLink BATTERY_STATUS
battery_status.cell_count = math::max(_params.n_cells, static_cast<int32_t>(1));
@ -245,6 +247,32 @@ void Battery::computeScale()
}
}
float Battery::computeRemainingTime(float current_a)
{
float time_remaining_s = -1.f;
// Only estimate remaining time with useful in flight current measurements
if (_current_filter_a.getState() > 1.f) {
// Initialize strongly filtered current to an estimated average consumption
if (_current_average_filter_a.getState() < 0.f) {
// TODO: better initial value based on "average current" from last flight
_current_average_filter_a.reset(15.f);
}
// Filter current very strong, we basically want the average consumption
_current_average_filter_a.update(current_a);
// Remaining time estimation only possible with capacity
if (_params.capacity > 0.f) {
const float remaining_capacity_mah = _state_of_charge * _params.capacity;
const float current_ma = _current_average_filter_a.getState() * 1e3f;
time_remaining_s = remaining_capacity_mah / current_ma * 3600.f;
}
}
return time_remaining_s;
}
void Battery::updateParams()
{
param_get(_param_handles.v_empty, &_params.v_empty);

6
src/lib/battery/battery.h
View File

@ -133,17 +133,19 @@ private:
void estimateStateOfCharge(const float voltage_v, const float current_a, const float throttle);
uint8_t determineWarning(float state_of_charge);
void computeScale();
float computeRemainingTime(float current_a);
uORB::PublicationMulti<battery_status_s> _battery_status_pub{ORB_ID(battery_status)};
bool _battery_initialized{false};
AlphaFilter<float> _voltage_filter_v;
AlphaFilter<float> _current_filter_a;
AlphaFilter<float> _current_average_filter_a;
AlphaFilter<float> _throttle_filter;
float _discharged_mah{0.f};
float _discharged_mah_loop{0.f};
float _state_of_charge_volt_based{-1.f}; // [0,1]
float _state_of_charge{-1.f}; // [0,1]
float _state_of_charge_volt_based{-1.f}; // [0,1]
float _state_of_charge{-1.f}; // [0,1]
float _scale{1.f};
uint8_t _warning{battery_status_s::BATTERY_WARNING_NONE};
hrt_abstime _last_timestamp{0};